Intermediate film for dimming glass and application of intermediate film

Abstract

The invention provides an intermediate film for switchable glass, the intermediate film comprises polyvinyl butyral resin, a plasticizer and polyether polyol, the glass transition temperature Tg of the intermediate film is less than or equal to 45 DEG C, and the crosslinking degree of the intermediate film after the intermediate film is crosslinked for 30-240 minutes at the temperature of 90-140 DEG C is 70-90%. And the prepared intermediate film has good adhesion and mechanical properties. After the intermediate film is applied to the dimming glass, not only can the dimming glass be endowed with excellent interface adhesion and mechanical stability, but also the problem of dimming performance degradation caused by migration and precipitation of a plasticizer can be fundamentally avoided, the service life of the dimming glass is remarkably prolonged, and the working stability of the dimming glass is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic light control materials, specifically to an intermediate film for dimming glass, dimming glass containing the intermediate film, and a method for preparing the same. Background Technology

[0002] A dimming glass is a light-controlling device, primarily consisting of a dimming film sandwiched between two layers of transparent glass. Types of dimming films include suspended particle dimming films (SPD), polymer-dispersed liquid crystal (PDLC) dimming films, electrochromic (EC) dimming films, dye-dispersed liquid crystal (DLC) dimming films, thermochromic (TC) dimming films, and photochromic (PC) dimming films. Dimming glass made using suspended particle dimming films, polymer-dispersed liquid crystal dimming films, and electrochromic dimming films are respectively called suspended particle dimming glass, polymer-dispersed liquid crystal dimming glass, and electrochromic dimming glass. When electricity is applied to suspended particle dimming glass, polymer-dispersed liquid crystal dimming glass, and electrochromic dimming glass, the arrangement or state of the materials in the dimming film changes, thereby altering the light transmission characteristics of the dimming glass, such as changing from low transmittance to high transmittance, or from high transmittance to low transmittance. This type of dimming glass, which can achieve rapid switching between on and off states through the action of electric field / current, has the advantages of actively controlling light transmittance and energy saving. This device can be used as smart windows, rearview mirrors, sunglasses, displays, etc. in fields such as spacecraft, high-speed rail, automobiles, and buildings.

[0003] In the traditional fabrication of suspended particle dimming glass, polymer-dispersed liquid crystal dimming glass, and electrochromic dimming glass, conventional PVB interlayer (Polyvinyl butyral interlayer) used in laminated glass is commonly employed. PVB resin itself is a rigid polymer, requiring the addition of a large amount of plasticizer to impart high elasticity, toughness, and adhesion properties, thereby meeting the application requirements of automotive windshields, architectural laminated glass, and other scenarios. Conventional PVB interlayer films primarily use aliphatic esters as plasticizers, specifically selected from triethylene glycol diisooctanoate, triethylene glycol dihexanoate, dibutyl sebacate, triethylene glycol dinonanoate, triethylene glycol diisooctanoate, and dioctyl dioctanoate. However, when using PVB interlayer films containing aliphatic ester plasticizers to prepare smart glass, a key technical defect exists: during long-term service of the smart glass, these aliphatic ester plasticizers are prone to migration and precipitation, penetrating into the functional layer of the smart film, causing the optical control performance of the smart film to fail, severely affecting the reliability of the smart glass. Therefore, developing a technical solution to replace these aliphatic ester plasticizers has become an urgent need to solve the above problems.

[0004] Therefore, developing a highly adaptable interlayer material to solve the core technical problem of dimming function failure caused by plasticizer migration and precipitation when using conventional PVB interlayers to prepare suspended particle dimming glass, polymer-dispersed liquid crystal dimming glass, and electrochromic dimming glass has become one of the key issues that front-line R&D personnel in the industry urgently need to overcome. Summary of the Invention

[0005] In view of this, the present invention aims to solve the technical problem of dimming function failure and performance degradation caused by plasticizer migration and precipitation when conventional PVB interlayer films containing aliphatic ester plasticizers are used to prepare dimming glass in the prior art. To this end, the present invention provides an interlayer film that can inhibit plasticizer migration at the source. This interlayer film adopts a specific polymer matrix and a plasticizer system that is more friendly to dimming films, and introduces polyether polyol as a functional component. After crosslinking, it forms a structure with a specific glass transition temperature and degree of crosslinking. This not only endows the dimming glass with excellent interfacial adhesion and mechanical stability, but also effectively "anchors" the plasticizer through multiple intermolecular forces, fundamentally preventing its migration, significantly extending the service life of the dimming glass and improving its working stability.

[0006] In a first aspect, the present invention provides an intermediate film comprising polyvinyl butyral resin, a plasticizer, and a polyether polyol;

[0007] The polyvinyl butyral resin has a mass content of 34.5-64.5 wt%, a weight-average molecular weight of 100,000-200,000, a melt flow rate of 5.0-10.0 g / 10 min, and a molar ratio of ethylene alcohol units to butyral units of (0.5-2.0):1.

[0008] The plasticizer has a mass content of 35-65 wt% and is selected from one or a combination of trimellitates or phthalates.

[0009] The polyether polyol has a mass content of 0.1~5wt%, and is selected from at least one of polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol, with a weight-average molecular weight range of 1000~10000.

[0010] The glass transition temperature Tg of the intermediate film is ≤45℃, and the degree of crosslinking after crosslinking at a temperature of 90~140℃ for a time of 30~240 minutes is 70~90%.

[0011] Further, the plasticizer is selected from at least one of diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dipentyl phthalate, dihexyl phthalate, diheptyl phthalate, dioctyl phthalate, di(2-ethylhexyl) phthalate, dinonyl phthalate, didecyl phthalate, diisodecyl phthalate, trimethyl trimellitate, triethyl trimellitate, tripropyl trimellitate, tri-n-butyl trimellitate, tri-n-pentyl trimellitate, tri-n-hexyl trimellitate, triisooctyl trimellitate, triisononyl trimellitate, trinonyl trimellitate, triisodecyl trimellitate, and tridecyl trimellitate.

[0012] It should be understood that the "crosslinking conditions" described in this invention correspond to the lamination process conditions in the subsequent dimming glass preparation process.

[0013] Furthermore, the intermediate film contains a UV absorber;

[0014] The UV absorber has a mass content of 0.1~5 wt%;

[0015] The UV absorber is selected from at least one of salicylates, benzophenones, benzotriazoles, triazines, trimethoxybenzoates, p-aminobenzoic acid, phenyl cinnamates, camphor derivatives, benzamides, and benzoxazines.

[0016] Furthermore, the intermediate membrane contains an IR absorber;

[0017] The IR absorber has a mass content of 0.1~5 wt%;

[0018] Furthermore, the intermediate film has an absorption rate of more than 60% for the near-infrared band (780~2500nm) in the solar spectrum.

[0019] Furthermore, the IR absorber is selected from at least one of indium tin oxide (ITO), antimony tin oxide (ATO), aluminum-doped zinc oxide (AZO), cesium tungsten bronze, lanthanum hexaboride (LaB6), tungsten bronze, cyanine dyes, phthalocyanine, naphthalene phthalocyanine, squaric acid cyanine, ketone acid dyes, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS).

[0020] Furthermore, the intermediate membrane contains an antioxidant;

[0021] The antioxidant content is 0.1~5 wt%;

[0022] The antioxidant is selected from at least one of hindered phenols, aromatic amines, phosphites, and thioesters.

[0023] Furthermore, the intermediate film contains a light stabilizer;

[0024] The light stabilizer has a mass content of 0.1~5 wt%;

[0025] The light stabilizer is selected from at least one of hindered amines.

[0026] Furthermore, the intermediate film contains a heat stabilizer;

[0027] The heat stabilizer has a mass content of 0.1~5 wt%;

[0028] The heat stabilizer is selected from at least one of dibutyltin laurylate, isooctyltin, and phosphite.

[0029] Furthermore, the intermediate membrane contains a silane coupling agent;

[0030] The silane coupling agent has a mass content of 0.1~5 wt%;

[0031] The silane coupling agent is selected from at least one of epoxy silane coupling agents, acryloyloxy silane coupling agents, alkyl silane coupling agents, amino silane coupling agents, vinyl silane coupling agents, and thiosilane coupling agents.

[0032] Furthermore, at least one surface of the intermediate film is provided with a roll-formed pattern.

[0033] A second aspect of the present invention provides a dimming glass, comprising:

[0034] First transparent substrate;

[0035] Second transparent substrate;

[0036] A dimming film disposed between the first transparent substrate and the second transparent substrate;

[0037] A first adhesive layer is provided between the first transparent substrate and the dimming film, and / or a second adhesive layer is provided between the second transparent substrate and the dimming film;

[0038] Wherein, the first interlayer and / or the second interlayer are the aforementioned intermediate film.

[0039] Furthermore, the dimming film is selected from any one of suspended particle dimming film, polymer dispersed liquid crystal dimming film, dye liquid crystal dimming film, or electrochromic dimming film.

[0040] Furthermore, the first transparent substrate and / or the second transparent substrate are selected from at least one of inorganic glass and organic glass.

[0041] Furthermore, there are no special restrictions on the type of inorganic glass. It can be any conventional transparent glass known to those skilled in the art. It can be ordinary glass or functional glass, such as UV blocking glass, IR blocking glass, Low-E glass, tempered glass or antibacterial glass, etc. It can also be selected from colored glass such as gray glass or brown glass.

[0042] Furthermore, there are no special restrictions on the type of plexiglass; any conventional transparent plexiglass known to those skilled in the art is acceptable. It can be PMMA board, PC board, or functional plexiglass, such as UV-blocking PC board, IR-blocking PC board, etc. It can also be selected from colored plexiglass such as gray plexiglass and brown plexiglass.

[0043] A third aspect of the present invention provides a method for preparing a dimming glass, comprising the following steps:

[0044] The dimming glass is obtained by laminating the layers according to the aforementioned structure of dimming glass.

[0045] In this invention, there are no special limitations on the method of adhesive bonding; any conventional adhesive bonding method in the art is acceptable, such as bonding adhesive in a laminator, or bonding adhesive in a high-pressure autoclave or adhesive bonding box / furnace.

[0046] Furthermore, the temperature of the lamination process is 90~140℃, the pressure is 0.1~1.5MPa, and the time is 30~240 minutes.

[0047] In a fourth aspect, the present invention provides a dimming glass article, which is prepared from the aforementioned dimming glass or the aforementioned preparation method.

[0048] During long-term aging, the migration and precipitation of plasticizers in PVB interlayer films cannot be completely prevented. Aliphatic ester plasticizers added to conventional PVB interlayer films can migrate and precipitate into the functional layer of the dimming film, adversely affecting its performance. For suspended particle dimming films, the poor compatibility of aliphatic ester plasticizers with the suspension medium can lead to nanoparticle aggregation, affecting performance. Polymer-dispersed liquid crystal dimming films are a hybrid system composed of a polymer matrix and liquid crystal; the migration and precipitation of plasticizers can interfere with both phases and their interface. Aliphatic ester plasticizers tend to soften the polymer matrix, weakening the polymer's anchoring effect on liquid crystal molecules, which is detrimental to the long-term operational stability of dimming devices.

[0049] Compared to aliphatic ester plasticizers, trimellitic ester / phthalic ester plasticizers have larger molecular sizes, stronger polarity, and are less prone to migration and precipitation. In addition, the benzene ring structure has excellent thermal stability and is not easily decomposed or volatilized, which is beneficial to the long-term working stability of dimming film devices.

[0050] Polyether polyols, acting as compatibility promoters, play a crucial role in systems composed of PVB resin and trimellit / phthalate plasticizers. After crosslinking, they can construct a unique "anchoring" structure, improving the compatibility between trimellit / phthalate plasticizers and PVB resin, thereby optimizing the overall performance of the interlayer. The mechanism of this "anchoring" effect mainly includes two aspects: First, the ether bonds and terminal hydroxyl groups on the polyether polyol molecular chain can form a broad hydrogen bond network with the hydroxyl groups in PVB resin and the ester groups in trimellit / phthalate plasticizer molecules, thus physically anchoring the plasticizer molecules in the resin matrix; second, during the crosslinking process, the terminal hydroxyl groups of the polyether polyol can participate in the reaction, becoming part of the chemical crosslinking network, further enhancing the binding of trimellit / phthalate plasticizer molecules. It is this "anchoring" effect that firmly locks trimellitate / phthalate plasticizer molecules into the system, effectively solving their migration problem during long-term service and achieving technical results superior to existing technologies.

[0051] The PVB interlayer film provided by this invention uses trimellitic ester or phthalate plasticizers, supplemented with functional components such as polyether polyols. This not only gives the dimming glass excellent interfacial adhesion and mechanical stability, but also fundamentally inhibits the dimming function attenuation caused by plasticizer migration and precipitation. It significantly improves the performance reliability and service life of the dimming glass during long-term service, and has important industrial application value and broad market prospects. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The accompanying drawings described below are merely embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0053] Figure 1 A schematic diagram of the cross-sectional structure of the dimming glass provided by the present invention;

[0054] Figure 2 The dimming glass of Comparative Example 1 of this invention was aged at 105°C for 250 hours, and the extract from the functional layer of the dimming film was obtained. 1 H NMR spectrum (partial);

[0055] Figure 3 Triethylene glycol diisooctyl ester plasticizer 1 H NMR spectrum;

[0056] Wherein, 1 is a first transparent substrate, 2 is a first interlayer adhesive layer, 3 is a dimming film, 4 is a second interlayer adhesive layer, and 5 is a second transparent substrate. Detailed Implementation

[0057] This invention provides a dimming glass with stable working performance and a significantly long lifespan.

[0058] In this invention, the concepts of the first transparent substrate, the second transparent substrate, the first adhesive layer, and the second adhesive layer only indicate the relative relationship between the two, and are not limiting conditions. They do not necessarily have to be a first and second relationship, and can also be positional relationships such as up, down, front, back, left, and right.

[0059] Glass transition temperature test (Tg): The glass transition temperature of the intermediate film is tested in accordance with ISO 11357-2 Differential scanning calorimetry (DSC) for plastics - Part 2: Determination of glass transition temperature.

[0060] Weight-average molecular weight (Mw) test: The weight-average molecular weight (Mw) of polyvinyl butyral resin was determined using gel permeation chromatography (GPC).

[0061] Melt mass flow rate (MFR) test: According to GB / T 3682.1-2018 Plastics Thermoplastics Determination of Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) Part 1: Standard Method, the melt mass flow rate (MFR) of polyvinyl butyral resin is tested. The higher the melt mass flow rate, the better the high-temperature fluidity of the material.

[0062] Test of the molar ratio of vinyl alcohol units to butyral units in polyvinyl butyral resin: using 1 H NMR was used to calculate the molar ratio of vinyl alcohol units to butyral units in the intermediate film polyvinyl butyral resin.

[0063] Crosslinking degree test: The crosslinking degree of the intermediate film was tested according to GB 18474-2001 Test method for crosslinking degree of crosslinked polyethylene (PE-X) pipes and fittings.

[0064] Adhesion test of switching glass: According to GB / T 32020-2015, the adhesion of switching glass is tested. The larger the tapping value, the stronger the adhesion.

[0065] Measurement of the dimming performance ΔT of smart glass: When the smart glass is not powered, the visible light transmittance is recorded as Toff. When the smart glass is connected to the corresponding power supply, the visible light transmittance is recorded as Ton. Therefore, ΔT = Ton - Toff. Different smart glasses have different power supplies. For example, suspended particle smart glass can generally be connected to 110V, 60Hz AC power; polymer-dispersed liquid crystal smart glass can generally be connected to 60V, 60Hz AC power; and electrochromic dimming glass can generally be connected to 3V DC power. Specific requirements depend on the product specifications.

[0066] High-Temperature Stability Test of Smart Glass: A 30cm x 30cm piece of smart glass was placed in a 105℃ forced-air oven, and the light transmittance was tested after different aging times. After the aging test, the smart film was disassembled, and the functional layer of the smart film was extracted. 1 1H NMR analysis indicates the presence of plasticizers. If plasticizers are present, it means that they have migrated, precipitated, and permeated into the functional layer of the dimming film.

[0067] To better illustrate the present invention, the following specific embodiments are provided.

[0068] Raw material preparation

[0069] Polyvinyl butyral resin (PVB resin) with weight average molecular weights of 120,000, 150,000, and 180,000, melt flow rates (MFR) of 6.0, 8.0, and 9.5 g / 10 min, and a molar ratio of vinyl alcohol units to butyral units of 1.0:1, 1.5:1, and 1.8:1, respectively, was selected. The plasticizers used were di(2-ethylhexyl) phthalate (DOP) and trioctyl trimellitate (TOTM). The polyether polyols used are polyethylene glycol (PEG, molecular weight 2000) and polypropylene glycol (PPG, molecular weight 4000); the functional additives used are UV absorbers (benzotriazole, UV-327), IR absorbers (inorganic, nano-tin antimony oxide), antioxidants (hindered phenols, 1010), light stabilizers (hindered amines, 770), heat stabilizers (dibutyltin laurylate), and silane coupling agents (epoxysilane, KH-560).

[0070] The dimming film is selected from polymer dispersed liquid crystal dimming film (PDLC), suspended particle dimming film (SPD), and electrochromic dimming film (EC); the transparent substrate is made of inorganic float glass (5mm thick).

[0071] Example 1

[0072] Intermediate membrane preparation:

[0073] The ingredients are prepared by weight percentage: 60wt% PVB resin (weight average molecular weight 150,000, MFR 8.0 g / 10 min, vinyl alcohol unit: butyral unit = 1.0:1), 35wt% DOP, and 5wt% PEG (molecular weight 2,000). The above raw materials are added to a mixer and mixed at 80°C for 30 min until homogeneous. The mixture is then extruded to obtain a 0.76 mm thick intermediate film, with a diamond pattern rolled onto its outer surface.

[0074] Intermediate membrane performance testing:

[0075] Glass transition temperature (Tg) 38℃; crosslinking of the intermediate film at 120℃ for 120 min, degree of crosslinking 82%.

[0076] Preparation of smart glass:

[0077] The first transparent substrate → first interlayer (the above-mentioned intermediate film) → dimming film (SPD) → second interlayer (the above-mentioned intermediate film) → second transparent substrate are stacked in sequence and placed in a laminator. The lamination process is carried out at 120°C and 0.8MPa pressure for 120 minutes to obtain dimming glass.

[0078] Performance testing of smart glass:

[0079] Adhesion impact value: 9; Initial dimming performance: Toff=0.5%, Ton=55.2%, ΔT=54.7%; After aging at 105℃ for 1000h, the ΔT decay rate is only 8%. 1 1H NMR analysis revealed the phenomenon of plasticizer migration and precipitation into the functional layer of the dimming film.

[0080] Example 2

[0081] Intermediate membrane preparation:

[0082] The ingredients were prepared according to the following mass percentages: PVB resin (weight average molecular weight 120,000, MFR 9.5 g / 10 min, vinyl alcohol units: butyral units = 1.5:1) 55 wt%, TOTM 40 wt%, PPG (molecular weight 4,000) 2.0 wt%, UV-327 1.2 wt%, antioxidant 1010 0.8 wt%, light stabilizer 770 0.6 wt%, and silane coupling agent KH-560 0.4 wt%. The raw material mixing and molding process were the same as in Example 1, resulting in an intermediate film with a thickness of 0.76 mm, with a striped pattern applied to a single surface by roll forming.

[0083] Intermediate membrane performance testing:

[0084] Tg 35℃; crosslinking at 130℃ for 90 min, degree of crosslinking 85%.

[0085] Preparation of smart glass:

[0086] The structure consists of a first transparent substrate → a first interlayer (the aforementioned intermediate film) → a dimming film (PDLC) → a second transparent substrate stacked sequentially, with the interlayer process being the same as in Example 1, resulting in dimming glass (with an interlayer only on one side).

[0087] Performance testing of smart glass:

[0088] Adhesion impact value: 9; Initial dimming performance: Toff = 2.5%, Ton = 67.3%, ΔT = 64.8%; After aging at 105℃ for 1000 hours, ΔT decay rate: 10%. 1 1H NMR analysis revealed the phenomenon of plasticizer migration and precipitation into the functional layer of the dimming film.

[0089] Example 3

[0090] Intermediate membrane preparation:

[0091] The ingredients were prepared according to the following mass percentages: 45 wt% PVB resin (weight average molecular weight 180,000, MFR 6.0 g / 10 min, vinyl alcohol units: butyral units = 1.8:1), 50 wt% DOP and TOTM compound (mass ratio 1:1), 1.0 wt% PEG (molecular weight 2000), 1.5 wt% IR absorber (nano-tin antimony oxide), 1.0 wt% antioxidant 1010, 1.0 wt% heat stabilizer (isooctylstannous), and 0.5 wt% silane coupling agent (aminosilane). The raw material mixing and molding process were the same as in Example 1, resulting in a pattern-free interlayer film.

[0092] Intermediate membrane performance testing:

[0093] Tg 42℃; after crosslinking at 110℃ for 180 min, the degree of crosslinking is 78%.

[0094] Preparation of smart glass:

[0095] The structure and lamination process are the same as in Example 1, and the dimming film is an electrochromic dimming film (EC).

[0096] Performance testing of smart glass:

[0097] Adhesion tapping value: 9; Initial dimming performance: Toff=1.0%, Ton=58.7%, ΔT=57.7%; After 1000 hours of high-temperature aging at 105℃, ΔT decay rate: 7%. 1 1H NMR analysis revealed the phenomenon of plasticizer migration and precipitation into the functional layer of the dimming film.

[0098] Comparative Example 1

[0099] Intermediate membrane preparation:

[0100] Except for replacing the plasticizer with an aliphatic ester plasticizer (triethylene glycol diisooctanoate, 3GO), the other raw materials, proportions and molding processes are the same as in Example 1.

[0101] Intermediate film and switching glass performance testing:

[0102] The intermediate film had a Tg of 40℃ and a crosslinking degree of 81%; the dimming glass had an adhesion knock value of 8, and initial dimming performance Toff=0.5%, Ton=54.8%, and ΔT=54.3%; after high-temperature aging at 105℃ for 250h, the ΔT decay rate reached 35%. The material of the dimming film functional layer of the high-temperature aged dimming glass was extracted and processed. 1 H NMR spectrum analysis, see Figure 2 The peaks at 4.24, 3.69, and 3.63 ppm are characteristic peaks of triethylene glycol diisooctanoate. Figure 3 The image shown is of pure triethylene glycol diisooctanoate. 1 1H NMR spectrum. The above data indicate that plasticizers migrated and precipitated into the functional layer of the dimming film after high-temperature aging treatment.

[0103] Comparative Example 2

[0104] Intermediate membrane preparation:

[0105] The content of plasticizer (TOTM) was adjusted to 10 wt%, the content of PVB resin was increased to 85 wt%, and the remaining raw materials, proportions and molding process were the same as in Example 2.

[0106] Intermediate film and switching glass performance testing:

[0107] The intermediate film has a Tg of 52℃ (exceeding the ≤45℃ requirement), poor flexibility, and a crosslinking degree of 82%. The adhesion strength of the dimming glass, measured by impact, is grade 8. Initial dimming performance is Toff=0.6%, Ton=57.9%, and ΔT=57.3%. After aging at 105℃ for 500 hours, the ΔT decay rate is 28%. 1 1H NMR analysis revealed the phenomenon of plasticizer migration and precipitation into the functional layer of the dimming film.

[0108] Comparative Example 3

[0109] Intermediate membrane preparation:

[0110] PVB resin with a weight average molecular weight of 60,000 was selected, and the other raw materials, proportions and molding processes were the same as in Example 3.

[0111] Intermediate film and switching glass performance testing:

[0112] Intermediate film Tg 40℃, intermediate film MFR 2.5g / 10min (exceeding the 5.0~10.0g / 10min range); crosslinking degree 65% (below the 70% requirement); dimming glass adhesion tapping value 6, initial dimming performance Toff=0.5%, Ton=57.8%, ΔT=57.3%; after high-temperature aging at 105℃ for 300h, interface delamination occurs, ΔT decay rate 40%, after... 1 1H NMR analysis revealed the phenomenon of plasticizer migration and precipitation into the functional layer of the dimming film.

[0113] Comparative Example 4

[0114] Intermediate membrane preparation:

[0115] Remove the polyether polyol, retain only PVB resin (same as in Example 1) and DOP, with a ratio of 60wt% PVB and 40wt% DOP. The rest of the process is the same as in Example 1.

[0116] Intermediate film and switching glass performance testing:

[0117] The intermediate film has a Tg of 41℃ and a crosslinking degree of 75%; its adhesion to the dimming glass has a knock value of 8, and its initial dimming performance is Toff=0.5%, Ton=53.2%, and ΔT=52.7%; after aging at 105℃ for 500 hours, yellowing appeared on the film surface, indicating that this intermediate film is prone to yellowing at high temperatures. 1 1H NMR analysis showed that plasticizers migrated and precipitated.

[0118] Table 1. Performance comparison of the intermediate film and switching glass prepared in the examples and comparative examples.

[0119]

[0120] As shown in Table 1, the interlayer film and dimming glass of the present invention, by selecting trimellitic ester / phthalic ester plasticizers and adding appropriate amounts of polyether polyols and other functional additives, and controlling PVB resin parameters, plasticizer content, and crosslinking conditions, exhibit significantly better interfacial adhesion, dimming performance stability, and high-temperature aging resistance than the comparative examples. The interlayer film and dimming glass prepared in Examples 1-3 showed a ΔT attenuation rate of less than 10% after 1000 hours of high-temperature aging, while the corresponding product in Comparative Example 1 showed a ΔT attenuation rate of 35% after 250 hours. This indicates that the present invention can fundamentally inhibit plasticizer migration and precipitation, solving the core problem of dimming function attenuation, and verifying the technical advantages and industrial application value of the present invention.

[0121] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An intermediate film for smart glass, characterized in that, Including polyvinyl butyral resin, plasticizers, and polyether polyols; The polyvinyl butyral resin has a mass content of 34.5-64.5 wt%, a weight-average molecular weight of 100,000-200,000, a melt flow rate of 5.0-10.0 g / 10 min, and a molar ratio of ethylene alcohol units to butyral units of (0.5-2.0):

1. The plasticizer has a mass content of 35-65 wt% and is selected from one or a combination of trimellitates or phthalates. The polyether polyol has a mass content of 0.1~5wt%, and is selected from at least one of polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol, with a weight-average molecular weight range of 1000~10000. The glass transition temperature Tg of the intermediate film is ≤45℃, and the degree of crosslinking after crosslinking at a temperature of 90~140℃ for a time of 30~240 minutes is 70~90%.

2. The intermediate film for dimming glass according to claim 1, characterized in that, The intermediate membrane contains a UV absorber; The UV absorber has a mass content of 0.1~5 wt%; The UV absorber is selected from at least one of salicylates, benzophenones, benzotriazoles, triazines, trimethoxybenzoates, p-aminobenzoic acid, phenyl cinnamates, camphor derivatives, benzamides, and benzoxazines.

3. The intermediate film for dimming glass according to claim 1, characterized in that, The intermediate membrane contains an IR absorber; The IR absorber has a mass content of 0.1~5 wt%; The IR absorber is selected from at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, cesium tungsten bronze, lanthanum hexaboride, tungsten bronze, cyanine dyes, phthalocyanine, naphthalene phthalocyanine, squaric acid cyanine, ketone acid dyes, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate.

4. The intermediate film for dimming glass according to claim 1, characterized in that, The intermediate membrane contains antioxidants; The antioxidant content is 0.1~5 wt%; The antioxidant is selected from at least one of hindered phenols, aromatic amines, phosphites, and thioesters.

5. The intermediate film for dimming glass according to claim 1, characterized in that, The intermediate film contains a light stabilizer; The light stabilizer has a mass content of 0.1~5 wt%; The light stabilizer is selected from at least one of hindered amines.

6. The intermediate film for dimming glass according to claim 1, characterized in that, The intermediate membrane contains a heat stabilizer; The heat stabilizer has a mass content of 0.1~5 wt%; The heat stabilizer is selected from at least one of dibutyltin laurylate, isooctyltin, and phosphite.

7. The intermediate film for dimming glass according to claim 1, characterized in that, The intermediate membrane contains a silane coupling agent; The silane coupling agent has a mass content of 0.1~5 wt%; The silane coupling agent is selected from at least one of epoxy silane coupling agents, acryloyloxy silane coupling agents, alkyl silane coupling agents, amino silane coupling agents, vinyl silane coupling agents, and thiosilane coupling agents.

8. The intermediate film for dimming glass according to claim 1, characterized in that, At least one surface of the intermediate film is provided with a roll-formed pattern.

9. A dimming glass, comprising, in sequence: First transparent substrate; Second transparent substrate; A dimming film disposed between the first transparent substrate and the second transparent substrate; A first adhesive layer is provided between the first transparent substrate and the dimming film, and / or a second adhesive layer is provided between the second transparent substrate and the dimming film; Wherein, the first interlayer and / or the second interlayer are the interlayer film for dimming glass as described in any one of claims 1 to 8.

10. The dimming glass according to claim 9, characterized in that, The dimming film is selected from any one of suspended particle dimming film, polymer dispersed liquid crystal dimming film, dye liquid crystal dimming film, or electrochromic dimming film.

11. The dimming glass according to claim 9, characterized in that, The first transparent substrate and / or the second transparent substrate are selected from at least one of inorganic glass and organic glass.

12. A method for preparing a switchable glass, comprising the following steps: The dimming glass is obtained by laminating the layers according to the structure of the dimming glass described in claim 9.

13. A dimming glass article, prepared from the dimming glass according to any one of claims 9 to 11 or the preparation method according to claim 12.

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