PVB interlayer with high barrier and low haze and its preparation method and application

Abstract

The present application relates to the technical field of PVB film preparation, in particular to a high-barrier low-haze PVB interlayer and its preparation method and application. To solve the technical contradiction that the heat insulation performance, optical performance and mechanical performance of the PVB interlayer are difficult to be considered in the prior art, the present application adopts the following technical scheme: the PVB interlayer has a three-layer symmetrical structure, the skin layer is a high-molecular-weight PVB adhesive layer; the core core layer comprises a molecular weight gradient blending matrix formed by ultra-high molecular weight PVB and low molecular weight PVB. The matrix cooperatively disperses absorbing infrared barrier agent, reflective infrared barrier agent, core-shell structure ultraviolet stabilizer, toughening agent and flame retardant, and realizes high-efficiency interface bonding through silane coupling agent. Through the ingenious structure function partition and material composite design, the present application realizes high infrared barrier rate, maintains low haze, and has excellent mechanical performance and super-long weather resistance stability, and has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of PVB film preparation technology, specifically to a high-barrier, low-haze PVB interlayer film, its preparation method, and its application. Background Technology

[0002] Polyvinyl butyral (PVB) interlayer is the core material of laminated safety glass, widely used in automotive windshields, building curtain walls, and rail transit windows. With the development of new energy vehicles and energy-efficient buildings, higher requirements are placed on PVB interlayer: it must effectively block near-infrared radiation from sunlight to reduce air conditioning energy consumption, while ensuring extremely high visible light transmittance and low haze to ensure clear driving visibility, and at the same time, it must meet stringent mechanical safety performance requirements.

[0003] To meet these needs, researchers have proposed several technical approaches. Patent CN121914495A discloses a scheme that modifies PVB resin through isobutyraldehyde copolymerization and adds cesium tin co-doped tungsten oxide as a heat-insulating agent and polycaprolactone micropowder as a flexibility reinforcing agent. This scheme uses a bulk blending method to uniformly mix all components in a single PVB resin. However, to ensure the mechanical properties of the interlayer, such as its anti-penetration properties, a high molecular weight PVB resin of 80,000-120,000 g / mol must be used, resulting in excessively high matrix melt viscosity. This makes the nano-heat-insulating agent prone to agglomeration, leading to high haze and insufficient infrared blocking efficiency. This scheme fails to resolve the contradiction between nano-dispersion and mechanical properties. Patent CN121801137A discloses an asymmetric composite membrane, in which a heat-shielding coating containing CsWO3 and ZnO is coated on one side of a PVB matrix. While this solution achieves a high infrared blocking rate, it suffers from inherent interface reliability issues with the coating: the adhesion between the coating and the PVB substrate is limited, with a peeling rate of 0.6-0.8% after 50 thermal cycles and a performance degradation of approximately 2.1%. Patent CN105835497A discloses a smart heat-insulating and sound-insulating PVB film, employing a three-layer co-extruded A / B / A structure and centrally adding VO2 nanoparticles as a heat-insulating agent to the core layer. Patent CN105778830A discloses a spectrally selective nano-heat-insulating PVB film, explicitly proposing a dual-mode heat shielding concept of near-infrared absorber + near-infrared reflector; however, its reflector mainly uses nano-sized metallic silver and other materials, and it fails to solve the engineering challenge of increased haze caused by the dispersion of large-sized reflective particles in the PVB bulk phase.

[0004] In summary, existing technologies suffer from the following unresolved contradictions: First, there is a contradiction between dispersion and strength. Bulk blending requires the use of high-viscosity PVB to improve strength, leading to nanoparticle agglomeration and increased haze. Second, there is a contradiction between the reliability of the coating and the substrate. Coating methods carry the risk of interfacial delamination and performance degradation after thermal cycling. Furthermore, there are engineering obstacles to dual-mode insulation. Absorbent nanoparticles and reflective micron-particles have different processing requirements; the former requires high shear, while the latter is susceptible to high shear. Simple blending can lead to the failure of one type of particle or a sharp increase in haze. Finally, existing technologies lack a systematic collaborative design, making it difficult to simultaneously achieve insulation, transparency, and strength. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-barrier, low-haze PVB interlayer membrane. By constructing a resin gradient and composite plasticizer as a foundation, and through the synergistic effect of dual-mode thermal shielding and multifunctional additives, ultra-low haze, ultra-high infrared barrier, excellent low-temperature penetration resistance, and long-term service stability are simultaneously achieved.

[0006] The present invention also provides a preparation method that is simple, easy to implement, and suitable for large-scale production.

[0007] The present invention also provides its application in the preparation of automotive laminated glass or building energy-saving glass.

[0008] The high-barrier, low-haze PVB interlayer of the present invention is an integrally formed A / B / A three-layer symmetrical structure, including two skin layers A and one core layer B; the thickness of skin layer A on one side is 0.06~0.12mm, and the thickness of core layer B is 0.26~0.52mm.

[0009] The skin layer A is made from the following parts by weight of raw materials:

[0010] First PVB resin: 100 parts;

[0011] Triethylene glycol diisooctanoate: 25-30 parts;

[0012] Polypropylene adipate: 2-8 parts;

[0013] Core-shell structured ultraviolet absorber: 0.3~1.0 parts;

[0014] Antioxidant: 0.05~0.2 parts;

[0015] Alkalinity regulator: 0.3~0.8 parts;

[0016] The core layer B is made from the following parts by weight of raw materials:

[0017] Second PVB resin blend: 134~176 parts;

[0018] Absorbing infrared blocking agent: 0.8~2.2 parts;

[0019] Reflective infrared blocking agent: 0.3~1.2 parts;

[0020] Polypropylene adipate: 10-24 parts;

[0021] Dispersant: 0.35~1.1 parts;

[0022] Silane coupling agent: 0.4~1.6 parts;

[0023] Flame retardant: 3-10 parts;

[0024] Core-shell structured ultraviolet absorber: 0.15~0.6 parts;

[0025] The first PVB resin has a weight-average molecular weight of 53,000~93,000 g / mol and a hydroxyl content of 19 wt.%.

[0026] The second PVB resin blend is a blend of ultra-high molecular weight PVB resin with a weight average molecular weight of 100,000~120,000 g / mol and a hydroxyl content of 13~19 wt.% and low molecular weight PVB resin with a weight average molecular weight of 16,000~24,000 g / mol and a hydroxyl content of 13~17 wt.%. The gradient design of hydroxyl content reduces the polarity of the core layer, and simultaneously optimizes the plasticizer absorption capacity and the dispersibility of low polar nanomaterials.

[0027] Low molecular weight PVB resin, as the continuous phase, provides an ultra-low viscosity melting environment. The extremely low melt viscosity translates to extremely low shear resistance, allowing absorbing nanoparticles and reflective microparticles to disperse easily and uniformly in a virtually unrestrained liquid environment, fundamentally preventing agglomeration. This is a prerequisite for achieving ultra-low haze and high-efficiency thermal insulation. This overturns the traditional thinking that "only a high-viscosity matrix can guarantee strength." Ultra-high molecular weight PVB resin, as the dispersed phase, forms a physical cross-linked network in the low-viscosity continuous phase during melt processing. After curing into a film, this network is "frozen" within it, thus endowing the final film material with macroscopic mechanical properties. These ultra-long molecular chains, like steel bars, entangle with each other in the low-viscosity matrix, constructing a flexible, highly tough three-dimensional network. This network compensates for the mechanical strength lost due to the use of low molecular weight PVB, ensuring that the core layer B still possesses excellent impact resistance and toughness.

[0028] The mixing mass ratio of the ultra-high molecular weight PVB resin and the low molecular weight PVB resin is (2~18):(65~70).

[0029] The first PVB resin is a medium-to-high molecular weight PVB resin, with a weight-average molecular weight significantly higher than that of the low molecular weight PVB resin in the second PVB resin blend, which aims to provide the PVB interlayer with excellent surface mechanical strength and adhesion to glass.

[0030] Using triethylene glycol diisooctanoate as a low molecular weight plasticizer and polypropylene adipate (PPA) with a number average molecular weight of 1000-2000 g / mol as a high molecular weight plasticizer, the two work synergistically to toughen the membrane. The concentration of PPA in the core layer (B) is higher than that in the skin layer (A). Most of the PPA is used in the core layer (B), with only a small amount retained in the skin layer (A) to ensure good interlayer integration with the core layer (B) matrix. This concentrates the high-cost, highly effective toughening plasticizer in the core layer (B), where toughness is most critical, forming a strong, flexible, and toughening network with the ultra-high molecular weight PVB chains in the core layer (B). This significantly improves the overall membrane's impact resistance at -20°C.

[0031] The physical cross-linking network formed by ultra-high molecular weight PVB in core layer B has a large mesh size, which can easily accommodate high molecular weight plasticizers with long molecular chains and large volumes. In contrast, the relatively dense mesh formed by lower molecular weight PVB in skin layer A has a steric repulsion effect on large-volume high molecular weight plasticizers. Simultaneously, the overall hydroxyl content of the PVB blend in core layer B is lower than that in skin layer A, resulting in lower polarity. Polyester plasticizers such as polypropylene adipate also have relatively low polarity. According to the principle of "like dissolves like," they tend to remain in the more polar core layer B, thus achieving selective enrichment of high molecular weight plasticizers in the core layer.

[0032] The antioxidant is antioxidant 1010.

[0033] The infrared blocking agent is cesium tungsten bronze.

[0034] The reflective infrared blocking agent is a hollow silica microsphere with a titanium dioxide shell on its surface, and the particle size is 1~2μm.

[0035] The microspheres have a hollow, two-shell structure, forming three interfaces with abrupt changes in refractive index: air-SiO2, SiO2-TiO2, and TiO2-PVB. Each interface can scatter and reflect incident near-infrared light, resulting in higher reflection efficiency compared to traditional solid particles. Their 1-2 μm micrometer-scale particle size falls precisely within the near-infrared band of 780-2500 nm, inducing strong Mie scattering to disperse infrared light in all directions, significantly enhancing the reflection of infrared heat. Their micrometer-scale size is much larger than the wavelength of visible light, thus avoiding effective scattering of visible light and fundamentally preventing the blue haze problem easily caused by nano-TiO2, ensuring the transparency of the glass.

[0036] The core-shell structured ultraviolet absorber has an organic ultraviolet absorber molecule as its core and an inorganic oxide as its shell. The ultraviolet absorber molecule (UVA) is preferably a benzotriazole, such as UV-326 or UV-328. The inorganic oxide is preferably silicon dioxide, denoted as UVA@SiO2. This structure effectively inhibits the migration and volatilization of organic ultraviolet absorber molecules, ensuring uniform dispersion near the cesium tungsten bronze, thus protecting the cesium tungsten bronze near-infrared absorber from ultraviolet light-induced photocatalytic degradation.

[0037] The core-shell structured UV absorber absorbs most UV rays in the outer layer A, preventing the PVB resin itself from aging and yellowing. Although most UV rays are blocked by the outer layer A, a small amount still penetrates to the core layer B. However, semiconductor nanomaterials like cesium tungsten bronze have photocatalytic activity and degrade under UV irradiation, leading to a decrease in thermal insulation performance. In the core-shell UVA@SiO2 form, UVA molecules are encapsulated in SiO2 and randomly and uniformly dispersed along with cesium tungsten bronze in the matrix of the core layer B. Based on high-density, uniformly distributed probability interception, this protects the cesium tungsten bronze, fundamentally ensuring the long-term stability of thermal insulation performance.

[0038] The flame retardant is epoxy resin-coated ammonium polyphosphate.

[0039] The preferred silane coupling agent is γ-aminopropyltriethoxysilane (KH550). Its mechanism of action is as follows: the siloxane end of KH550 forms stable covalent bonds with the metal-hydroxyl or silicon-hydroxyl groups on the surface of cesium tungsten bronze, hollow silica microspheres coated with titanium dioxide shells, and UVA@SiO2 particles through hydrolysis and condensation reactions; the amino end of KH550 achieves strong chemical bonding through efficient ring-opening addition reactions with the epoxy groups of epoxy-coated ammonium polyphosphate; this amino end can also form a strong hydrogen bond network with the hydroxyl groups in the PVB resin molecular chain. Through this composite effect of "multi-point anchoring and classified coupling," KH550 builds a solid "molecular bridge" between various fillers and the PVB matrix, which not only greatly improves the dispersibility and interfacial bonding of the fillers but also effectively enhances the adhesion durability of the final film and glass in humid and hot environments, ensuring the long-term service safety of laminated glass.

[0040] The dispersant is polyvinylpyrrolidone.

[0041] The alkalinity regulator is a mixture of sodium acetate and potassium acetate.

[0042] The method for preparing the high-barrier, low-haze PVB interlayer film of the present invention comprises the following steps:

[0043] (1) Preparation of the cortex A mixture:

[0044] Take the first PVB resin, triethylene glycol diisooctanoate, polypropylene adipate, core-shell structure ultraviolet absorber, antioxidant, and alkalinity regulator and mix them evenly to obtain the skin layer A mixture.

[0045] (2) Preparation of core layer B1 masterbatch:

[0046] Low molecular weight PVB resin, ultra-high molecular weight PVB resin, infrared absorber, polypropylene adipate, dispersant, and silane coupling agent are granulated in a twin-screw extruder at a temperature range of 150-170℃ to obtain core layer B1 masterbatch.

[0047] (3) Preparation of core layer B2 masterbatch:

[0048] Low molecular weight PVB resin, ultra-high molecular weight PVB resin, reflective infrared blocking agent, polypropylene adipate, dispersant, silane coupling agent, core-shell structure ultraviolet absorber, and flame retardant are granulated in a twin-screw extruder at a temperature range of 150-165℃ to obtain B2 masterbatch.

[0049] (4) Three-layer co-extrusion preparation

[0050] First extruder: Add the skin layer A mixture; Second extruder: Add the mixed masterbatch of core layer B1 masterbatch and core layer B2 masterbatch; The distributor forms an initial A / B / A three-layer structure, which is extruded through a T-die, pulled, cooled and shaped on a 45℃ embossing roller, and then wound up to obtain a high-barrier, low-haze PVB intermediate film.

[0051] The screw speed of the twin-screw extruder in step (2) is 200~300 rpm, and the screw speed of the twin-screw extruder in step (3) is 100~150 rpm, in order to protect the core and shell structure.

[0052] Step (4) The temperature of the first extruder is set to 160-175℃ and the screw speed is 30-40 rpm; Step (4) The temperature of the second extruder is set to 150-170℃ and the screw speed is 40-50 rpm.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] 1. This invention is the first to integrate molecular weight and hydroxyl dual gradient, absorption and reflection dual-mode thermal shielding, directional enrichment of composite plasticizer, long-term stability of core-shell structure ultraviolet absorber, epoxy resin-coated polyphosphate ammonium flame retardant reinforcement and KH550 interface reinforcement into an A / B / A three-layer symmetrical structure, forming a synergistic functional network that supports each other and is mutually causal.

[0055] 2. This invention actively uses low molecular weight PVB resin in the core layer to obtain an ultra-low melt viscosity environment, so that the cesium tungsten bronze and the hollow silica microspheres with titanium dioxide shells on the surface can achieve excellent dispersion. At the same time, the mechanical properties are compensated by the physical cross-linking network of ultra-high molecular weight PVB resin, which completely overturns the industry prejudice that low molecular weight PVB cannot be used for structural load-bearing layers.

[0056] 3. The ultra-low viscosity environment of the core layer B described in this invention enables the reflective micron-sized core-shell particles to perform effective reflection while being encapsulated, avoiding the high haze defect in conventional high-viscosity matrices, and achieving true synergistic effect between the two types of heat insulation agents: absorption and reflection.

[0057] 4. This invention achieves excellent dispersion through molecular weight classification design. The gradient reduction of hydroxyl content in the core layer improves compatibility with low-polarity plasticizers and hydrophobic nanomaterials. With the addition of KH550 interface enhancement and uniform distribution of core-shell structured ultraviolet absorbers, the haze of the intermediate film can be as low as that of existing technologies.

[0058] 5. The composite plasticizer gradient design of this invention enables the selective enrichment of high molecular weight plasticizer in the core layer B, which synergistically forms a flexible toughening network with ultra-high molecular weight PVB chains, giving the membrane excellent low-temperature toughness.

[0059] 6. The present invention adopts a method of first preparing functional masterbatch and then co-extruding, which simplifies the complex feeding system required by traditional three-material co-extrusion, and reduces equipment investment and process control difficulty.

[0060] 7. The core-shell structure of the ultraviolet absorber described in this invention disperses the organic ultraviolet absorber near nano- and micro-sized particles, thus protecting the cesium tungsten bronze nanoparticles. Infrared blocking attenuation after aging is ≤2%. The introduction of epoxy resin-coated ammonium polyphosphate flame retardant enables the laminated glass to achieve a GB8624 B1 flame-retardant rating, filling the market gap where existing heat-insulating PVB films generally lack flame-retardant functionality. Detailed Implementation

[0061] The present invention will be further described below with reference to the embodiments.

[0062] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0063] First PVB resin: High molecular weight:

[0064] S-LEC BM-2(Z), Sekisui Chemicals, Japan, weight-average molecular weight 53000 g / mol, hydroxyl content 19 wt.%;

[0065] S-LEC BH-6, Sekisui Chemicals, Japan, weight-average molecular weight 93000 g / mol, hydroxyl group 19 wt.%;

[0066] Second PVB resin: Low molecular weight:

[0067] S-LEC BL-10, Sekisui Chemicals, Japan, weight-average molecular weight 16000 g / mol, hydroxyl content 17 wt.%;

[0068] S-LEC BL-S, Sekisui Chemicals, Japan, with a weight-average molecular weight of 24,000 g / mol and 13 wt.% hydroxyl groups.

[0069] Second PVB resin: Ultra-high molecular weight:

[0070] S-LEC BH-3(Z) Sekisui Chemicals, Japan, weight-average molecular weight 108000 g / mol, hydroxyl group 13 wt.%;

[0071] S-LEC BH-A Sekisui Chemicals, Japan, weight-average molecular weight 116000 g / mol, hydroxyl group 19 wt.%;

[0072] Cesium tungsten bronze nanopowder (CsxWO3, x < 0.33) CY-XW30, Zhejiang Jiupeng New Materials Co., Ltd., particle size 30-50nm, purity ≥ 99.9%, specific surface area 20-50m². 2 / g.

[0073] Polypropylene adipate, number average molecular weight 1500 g / mol;

[0074] Flame retardant: Epoxy resin coated ammonium polyphosphate: GD-APP103, Zhejiang Longyou Gode Chemical Co., Ltd.;

[0075] Polyvinylpyrrolidone (dispersant) PVP K30, BASF AG.

[0076] Preparation of hollow SiO2@TiO2 double-shell microspheres:

[0077] Step 1: Preparation of calcium carbonate template microspheres

[0078] In a reaction vessel, 300 mL of a 2.0 g / L aqueous solution of polyacrylic acid (PAA, number average molecular weight 5000 g / mol) was added as a stabilizer solution, and the system temperature was maintained at 25 °C at a rotation speed of 400 rpm. Simultaneously, a 0.5 mol / L aqueous solution of calcium chloride and a 0.5 mol / L aqueous solution of anhydrous sodium carbonate were pumped in at a constant rate of 2.0 mL / min. During the reaction, the pH of the reaction system was precisely maintained at 9.5 ± 0.2 by micro-droplet addition of dilute NaOH or HCl. After the feeding was completed, the mixture was aged for another 2 hours. Subsequently, spherical CaCO3 template microspheres with a particle size distribution of 1.0–1.5 μm were obtained by centrifugation, alternating washing with deionized water and ethanol, and vacuum drying at 60 °C for 12 hours.

[0079] Step 2: One-pot continuous coating of SiO2 inner shell and TiO2 outer shell

[0080] SiO2 inner-shell coating: 10 parts by mass of CaCO3 template microspheres were weighed and dispersed in a mixed solvent consisting of 200 parts by mass of anhydrous ethanol, 40 parts by mass of deionized water, and 20 parts by mass of 28 wt.% ammonia. The mixture was then sonicated to homogenize it. While continuously stirring, a solution consisting of 30 parts by mass of tetraethyl orthosilicate (TEOS) and 30 parts by mass of ethanol was slowly added dropwise to the suspension at a rate of 0.5 mL / min. After the addition was complete, the reaction was continued at room temperature for 6 hours to form a CaCO3@SiO2 core-shell structure. No product separation was performed in this process; the process proceeded directly to the next step.

[0081] Smooth transition of the reaction environment:

[0082] In the aforementioned CaCO3@SiO2 suspension system, a constant-pressure dropping funnel was set up, filled with a 0.5 mol / L aqueous acetic acid solution. Under continuous stirring at 300 rpm, the acetic acid solution was slowly added dropwise, controlling the dropping rate so that the pH of the system decreased uniformly and steadily from an initial alkaline state to a weakly acidic state within 30 minutes, eventually stabilizing in the range of 4.5-5.0. During this process, it was ensured that no significant flocculation or precipitation occurred in the suspension.

[0083] Continuous TiO2 shell coating: After the pH of the system stabilized at 4.5-5.0, a solution consisting of 25 parts by mass of tetrabutyl titanate (TBOT) and 50 parts by mass of ethanol was slowly added dropwise to the suspension at a rate of 0.5 mL / min using a peristaltic pump. After the addition was complete, the reaction was continued to be stirred at room temperature for 4 hours to complete the TiO2 shell coating.

[0084] After the reaction was completed, the obtained three-layer CaCO3@SiO2@TiO2 microspheres were collected by centrifugation, washed several times with ethanol, and dried under vacuum at 60°C for 12 hours.

[0085] Step 3: Template etching and calcination crystallization

[0086] Ten parts by mass of the dried powder obtained in step two were slowly added to 300 parts by mass of 0.2 mol / L dilute hydrochloric acid, and gently stirred until CO2 bubbles stopped being generated. The product was centrifuged and washed repeatedly with a large amount of deionized water until neutral. The washed product, which was then washed once more with ethanol, was dried at 80°C and placed in a muffle furnace, where it was calcined at 450°C for 2 hours. After cooling, hollow SiO2@TiO2 double-shell microspheres were obtained, and the particle size was found to be in the range of 1~2 μm using laser particle size analysis.

[0087] Preparation of core-shell structured UVA@SiO2 ultraviolet absorber

[0088] Step 1: Preparation of precursor mixed solution

[0089] Add 50 parts by weight of ethanol to the reaction vessel. Start stirring and slowly add 2.0 parts by weight of UV 326, stirring until completely dissolved to form a clear solution. Continue stirring and add 1.0 part by weight of tetraethyl orthosilicate, 1.5 parts by weight of 28 wt.% ammonia as a catalyst, and 5.0 parts by weight of deionized water for hydrolysis. Continue stirring for 15 minutes to ensure all components are mixed homogeneously, forming a stable precursor mixture solution.

[0090] Step 2: Induced precipitation and in-situ coating

[0091] In another reaction vessel, add 100 parts by mass of deionized water. Start stirring and maintain the speed at 300 rpm. Using a peristaltic pump, add the precursor mixture dropwise to the stirred deionized water at a constant rate of 1.0 mL / min. Simultaneously, under the catalysis of ammonia, tetraethyl orthosilicate dissolved in the ethanol / aqueous phase undergoes hydrolysis and condensation reactions, preferentially nucleating and growing on the surface of UVA to form a dense SiO2 shell.

[0092] Step 3: Aging and Post-processing

[0093] After the addition was complete, the reactor was sealed, and the reaction was continued with stirring at room temperature for 18 hours for aging. After the reaction was completed, the resulting milky white suspension was centrifuged, and the white precipitate was collected. The precipitate was washed three times with anhydrous ethanol to remove any uncoated UVA, residual ammonia, and other impurities. The washed product was dried in a vacuum oven at 50°C for 12 hours. Finally, the dried product was subjected to air jet milling and sieved to remove hard agglomerates, resulting in a free-flowing UVA@SiO2 core-shell nanoparticle powder with a particle size in the range of 30-50 nm.

[0094] Example 1

[0095] The method for preparing the high-barrier, low-haze PVB interlayer film comprises the following steps:

[0096] (1) Preparation of the cortex A mixture:

[0097] Take 100 parts (by weight, the same below) of high molecular weight PVB resin S-LEC BM-2(Z) (weight average molecular weight 53000 g / mol, hydroxyl 19 wt.%), add 28 parts of triethylene glycol diisooctanoate, 4 parts of polypropylene adipate (number average molecular weight 1500 g / mol), 0.6 parts of UV absorber UVA@SiO2, 0.1 parts of antioxidant 1010, and 0.5 parts of composite alkalinity regulator (sodium acetate: potassium acetate = 2:1, mass ratio), and mix in a high-speed mixer at 500 rpm for 15 min to obtain the skin layer A mixture;

[0098] (2) Preparation of core layer B1 masterbatch:

[0099] Take 70 parts of low molecular weight PVB resin S-LEC BL-10 (weight average molecular weight 16000 g / mol, hydroxyl 17 wt.%), 8 parts of ultra-high molecular weight PVB resin S-LEC BH-A (weight average molecular weight 116000 g / mol, hydroxyl 19 wt.%), 1.5 parts of infrared absorption blocking agent CY-XW30, 8 parts of polypropylene adipate (number average molecular weight 1500 g / mol), 0.4 parts of dispersant PVP K30, and 0.5 parts of KH550 silane coupling agent. Granulate the mixture using a twin-screw extruder at a temperature range of 150-170℃ and a screw speed of 200 rpm to obtain core layer B1 masterbatch.

[0100] (3) Preparation of core layer B2 masterbatch:

[0101] Take 70 parts of low molecular weight PVB resin S-LEC BL-10 (weight average molecular weight 16000 g / mol, hydroxyl 17 wt.%), 8 parts of ultra-high molecular weight PVB resin S-LEC BH-A (weight average molecular weight 116000 g / mol, hydroxyl 19 wt.%), 0.8 parts of reflective infrared blocking agent hollow SiO2@TiO2 double-shell microspheres, 8 parts of polypropylene adipate (number average molecular weight 1500 g / mol), 0.3 parts of dispersant PVP K30, 0.5 parts of KH550 silane coupling agent, 0.3 parts of ultraviolet absorber UVA@SiO2, and 6.0 parts of GD-APP103 flame retardant. Granulate the mixture using a twin-screw extruder at a temperature range of 150-165℃ and a screw speed of 150 rpm to protect the core-shell structure, and obtain core layer B2 masterbatch.

[0102] B1 masterbatch and B2 masterbatch are mixed to obtain core layer mixed masterbatch;

[0103] (4) Three-layer co-extrusion preparation

[0104] First extruder: Add skin layer A mixture, set temperature 160-175℃, screw speed 30rpm; Second extruder: Add core layer mixing masterbatch, set temperature 150-170℃, screw speed 40rpm; The distributor forms an initial A / B / A three-layer structure, which is extruded through a T-die, drawn onto a 45℃ embossing roller for cooling and shaping, and then wound up to obtain a PVB intermediate film with a thickness of 0.76mm, a core layer thickness of 0.52mm, and a single-sided skin layer thickness of 0.12mm.

[0105] Example 2

[0106] The method for preparing the high-barrier, low-haze PVB interlayer film comprises the following steps:

[0107] (1) Preparation of the cortex A mixture:

[0108] Take 100 parts (by weight, the same below) of high molecular weight PVB resin S-LEC BH-6 (weight average molecular weight 93000 g / mol, hydroxyl 19 wt.%), add 25 parts of triethylene glycol diisooctanoate, 2 parts of polypropylene adipate (number average molecular weight 1500 g / mol), 0.3 parts of UV absorber UVA@SiO2, 0.05 parts of antioxidant 1010, and 0.5 parts of composite alkalinity regulator (sodium acetate: potassium acetate = 2:1, mass ratio), and mix in a high-speed mixer at 500 rpm for 15 min to obtain the skin layer A mixture;

[0109] (2) Preparation of core layer B1 masterbatch:

[0110] Take 65 parts of low molecular weight PVB resin S-LEC BL-S (24000g / mol, hydroxyl 13wt.%), 2 parts of ultra-high molecular weight PVB resin S-LEC BH-3(Z) (weight average molecular weight 108000g / mol, hydroxyl 13wt.%), 0.8 parts of absorption-type infrared blocking agent CY-XW30, 5 parts of polypropylene adipate (number average molecular weight 1500g / mol), 0.2 parts of dispersant PVP K30, and 0.2 parts of KH550 silane coupling agent. Granulate the mixture using a twin-screw extruder at a temperature range of 150-170℃ and a screw speed of 250rpm to obtain core layer B1 masterbatch.

[0111] (3) Preparation of core layer B2 masterbatch:

[0112] Take 65 parts of low molecular weight PVB resin S-LEC BL-S (24000g / mol, hydroxyl 13wt.%), 2 parts of ultra-high molecular weight PVB resin S-LEC BH-3(Z) (weight average molecular weight 108000g / mol, hydroxyl 13wt.%), 0.3 parts of reflective infrared blocking agent hollow SiO2@TiO2 double-shell microspheres, 5 parts of polypropylene adipate (number average molecular weight 1500g / mol), 0.15 parts of dispersant PVPK30, 0.2 parts of KH550 silane coupling agent, 0.15 parts of ultraviolet absorber UVA@SiO2, and 3.0 parts of GD-APP103 flame retardant. Granulate the mixture using a twin-screw extruder at a temperature range of 150-165℃ and a screw speed of 100 rpm to protect the core-shell structure, and obtain core layer B2 masterbatch.

[0113] B1 masterbatch and B2 masterbatch are mixed to obtain core layer mixed masterbatch;

[0114] (4) Three-layer co-extrusion preparation

[0115] First extruder: Add skin layer A mixture, set temperature 160-175℃, screw speed 30rpm; Second extruder: Add core layer mixing masterbatch, set temperature 150-170℃, screw speed 40rpm; The distributor forms an initial A / B / A three-layer structure, which is extruded through a T-die, drawn onto a 45℃ embossing roller for cooling and shaping, and then wound up to obtain a PVB intermediate film with a thickness of 0.38mm, a core layer thickness of 0.26mm, and a single-sided skin layer thickness of 0.06mm.

[0116] Example 3

[0117] The method for preparing the high-barrier, low-haze PVB interlayer film comprises the following steps:

[0118] (1) Preparation of the cortex A mixture:

[0119] Take 100 parts (by weight, the same below) of high molecular weight PVB resin S-LEC BM-2(Z) (weight average molecular weight 53000 g / mol, hydroxyl 19wt.%), add 30 parts of triethylene glycol diisooctanoate, 8 parts of polypropylene adipate (number average molecular weight 1500 g / mol), 1.0 part of UV absorber UVA@SiO2, 0.2 parts of antioxidant 1010, and 0.8 parts of composite alkalinity regulator (sodium acetate: potassium acetate = 2:1, mass ratio), mix in a high-speed mixer at 500 rpm for 15 min to obtain the skin layer A mixture;

[0120] (2) Preparation of core layer B1 masterbatch:

[0121] Take 70 parts of low molecular weight PVB resin S-LEC BL-10 (16000g / mol, hydroxyl 17wt.%), 18 parts of ultra-high molecular weight PVB resin S-LEC BH-A (weight average molecular weight 116000g / mol, hydroxyl 19wt.%), 2.2 parts of absorption-type infrared blocking agent CY-XW30, 12 parts of polypropylene adipate (number average molecular weight 1500g / mol), 0.6 parts of dispersant PVP K30, and 0.8 parts of KH550 silane coupling agent. Granulate the mixture using a twin-screw extruder at a temperature range of 150-170℃ and a screw speed of 300rpm to obtain core layer B1 masterbatch.

[0122] (3) Preparation of core layer B2 masterbatch:

[0123] Take 70 parts of low molecular weight PVB resin S-LEC BL-10 (16000g / mol, hydroxyl 17wt.%), 18 parts of ultra-high molecular weight PVB resin S-LEC BH-A (weight average molecular weight 116000g / mol, hydroxyl 19wt.%), 1.2 parts of reflective infrared blocking agent hollow SiO2@TiO2 double-shell microspheres, 12 parts of polypropylene adipate (number average molecular weight 1500g / mol), 0.5 parts of dispersant PVPK30, 0.8 parts of KH550 silane coupling agent, 0.6 parts of ultraviolet absorber UVA@SiO2, and 10.0 parts of GD-APP103 flame retardant. Granulate the mixture using a twin-screw extruder at a temperature range of 150-165℃ and a screw speed of 150 rpm to protect the core-shell structure, and obtain core layer B2 masterbatch.

[0124] B1 masterbatch and B2 masterbatch are mixed to obtain core layer mixed masterbatch;

[0125] (4) Three-layer co-extrusion preparation

[0126] First extruder: Add skin layer A mixture, set temperature 160-175℃, screw speed 30rpm; Second extruder: Add core layer mixing masterbatch, set temperature 150-170℃, screw speed 40rpm; The distributor forms an initial A / B / A three-layer structure, which is extruded through a T-die, drawn onto a 45℃ embossing roller for cooling and shaping, and then wound up to obtain a PVB intermediate film with a thickness of 0.76mm, a core layer thickness of 0.52mm, and a single-sided skin layer thickness of 0.12mm.

[0127] Comparative Example 1

[0128] Similar to Example 1, all PVB resins were replaced with an equal mass of S-LEC BM-2(Z) resin, and the other materials were blended together and cast into a single layer to form a 0.76 mm thick film.

[0129] Comparative Example 2

[0130] Same as Example 1, except that the ultra-high molecular weight PVB resin S-LEC BH-A in steps (2) and (3) is replaced by an equal mass of low molecular weight PVB resin S-LEC BL-10.

[0131] Comparative Example 3

[0132] Same as Example 1, except that an A / B / A structure is used, but both the core layer and the skin layer use a single high molecular weight PVB resin S-LEC BM-2(Z).

[0133] Comparative Example 4

[0134] Same as Example 1, except that instead of using core-shell UVA@SiO2, UV-326 of equal mass is used.

[0135] Comparative Example 5

[0136] Same as Example 1, except that the high molecular weight plasticizer polypropylene adipate is not used.

[0137] Comparative Example 6

[0138] Same as Example 1, except that no flame retardant is used.

[0139] Comparative Example 7

[0140] Same as Example 1, except that KH550 is removed.

[0141] The PVB interlayers prepared in the above embodiments and comparative examples were used to prepare laminated glass:

[0142] Two pieces of automotive-grade float glass with a thickness of 2.0 mm were used. After thorough cleaning and drying, a 2 wt.% KH-550 aqueous solution was uniformly sprayed onto the surface that would contact the PVB film. The glass was then baked in a 120°C oven for 30 minutes to form a silane pretreatment layer that enhances adhesion. The PVB interlayer film, prepared according to the examples and comparative examples, was cut to the appropriate size and placed between the two pretreated glass pieces. The pre-compressed assembly was placed in a vacuum bag and pre-compressed for 30 minutes at a vacuum of not less than -0.09 MPa and a temperature of 80-100°C to remove air. Subsequently, the pre-compressed assembly was transferred to an autoclave and held at a pressure of 1.2-1.5 MPa and a temperature of 140-145°C for 30 minutes. After the pressure holding period, the assembly was cooled to room temperature while maintaining pressure to obtain the final laminated glass test sample.

[0143] Unless otherwise stated, all performance tests are based on the laminated glass samples or PVB interlayers prepared above and are performed in accordance with the relevant national standards.

[0144] Optical performance (test object: laminated glass): Visible light transmittance (550nm), haze (%) and near-infrared blocking rate (average value of 780-2500nm) were tested using a spectrophotometer in accordance with GB / T 2680-2021.

[0145] Mechanical properties (test subject: laminated glass / PVB film):

[0146] Tensile strength (test object: PVB interlayer): Tested in accordance with GB / T 1040.3-2006.

[0147] Peel strength (test object: laminated glass): According to GB / T 28532-2012, the test was conducted using a tensile testing machine at 23±2℃ and a speed of 50 mm / min.

[0148] Low-temperature penetration resistance (test object: laminated glass): Refer to the falling ball impact test in Appendix A of GB 9656-2021. After freezing the sample at -20℃ for 4 hours, impact it with a 2260g steel ball from a height of 4m, and record the number of times the sample is not penetrated in 10 impacts.

[0149] Durability performance (test subject: laminated glass):

[0150] Radiation resistance (QUV accelerated aging): Tested according to GB / T 16422.3, using UVA-340 lamps, irradiance 0.89 W / m². 2 The sample was subjected to a cycle of 60℃ light exposure for 4 hours and 50℃ condensation for 4 hours, for a total of 1000 hours. The changes in infrared blocking rate before and after aging were recorded, and the attenuation rate was calculated.

[0151] Peel strength after humid heat aging: Referring to GB 9656-2021, the laminated glass sample was placed in a constant temperature and humidity chamber at 50℃ and 95%RH for 2 weeks and then taken out to test its peel strength according to the above method.

[0152] Combustion performance (test object: laminated glass): tested and rated according to GB 8624-2012.

[0153] The test results are shown in Table 1 below:

[0154] Table 1 Test Results

[0155]

[0156] As can be seen from the test results in Table 1, the PVB interlayer film and its laminated glass prepared in Examples 1-3 of this invention exhibit significant superiority in overall performance compared to the comparative examples. The specific analysis is as follows:

[0157] Examples 1, 2, and 3 all employ the core technical solutions of this invention. Their common advantages are: simultaneously achieving high infrared blocking rate and extremely low haze, breaking the bottleneck of traditional high-insulation films where "high insulation inevitably leads to high haze"; furthermore, thanks to the toughening design of core layer B, excellent low-temperature penetration resistance; and through the application of core-shell UVA@SiO2 stabilizers, excellent radiation aging resistance is achieved; the introduction of silane coupling agents ensures adhesion stability under humid and hot environments; and the synergistic effect of APP flame retardant endows the product with B1-level flame retardant performance. These comprehensive advantages are unmatched by any of the comparative examples.

[0158] Comparative Example 1 shows that all components were uniformly mixed in a single-layer film. Its infrared blocking rate decreased significantly, haze increased sharply to 1.15%, and peel strength and resistance to damp heat also deteriorated severely. This demonstrates that the three-layer symmetrical structure of this invention is key to achieving high thermal insulation, low haze, and strong adhesion. Through functional partitioning, it avoids interference from the thermal insulation filler on adhesion and optical properties.

[0159] In Comparative Example 2, no ultra-high molecular weight PVB resin was added to the core layer B. The result was a sharp drop in tensile strength to 16.8 MPa, and complete failure of penetration resistance at -20°C (0 passes). This precisely demonstrates the indispensability of ultra-high molecular weight PVB as a molecular framework in the core layer, playing a decisive role in the mechanical strength and impact toughness of the membrane. The haze did not decrease significantly, but rather increased slightly, possibly due to the lack of entanglement and stabilization from the ultra-high molecular weight PVB resin, leading to microscopic agglomeration of fillers in the low molecular weight matrix.

[0160] Comparative Example 3, lacking a molecular weight gradient, exhibited acceptable mechanical strength, but its infrared blocking rate and haze control were inferior to Example 1, and its aging resistance decreased. This demonstrates that the gradient design of ultra-high molecular weight PVB and low molecular weight PVB in the core layer B of this invention achieves a division of labor: the low molecular weight PVB resin component has good affinity and low viscosity, acting like a solvent to fully wet and efficiently disperse the thermal insulation filler; while the high molecular weight PVB resin component constructs a stable mechanical and spatial network. This synergistic effect is unattainable by any single molecular weight PVB through compromise. Therefore, the molecular weight gradient design is the core technical means by which this invention solves the industry problem of stable dispersion of high-load fillers, and is crucial for simultaneously improving optical performance, mechanical properties, and durability.

[0161] Comparative Example 4 used uncoated UV 326. Its initial performance was similar to that of Example 1, but after QUV aging, the infrared blocking rate decreased by as much as 12.5%. This demonstrates that the core-shell UVA@SiO2 stabilizer of the present invention can effectively prevent the migration and degradation of UVA and has a synergistic protective effect with the absorptive infrared blocking agent CY-XW30, greatly improving the long-term thermal insulation stability of the product.

[0162] Comparative Example 5 did not contain the high molecular weight plasticizer polypropylene adipate. Its penetration resistance at -20℃ deteriorated significantly, passing only twice, demonstrating that the high molecular weight plasticizer polypropylene adipate, as a toughening agent for core layer B, is a core element for achieving excellent low-temperature impact toughness.

[0163] Comparative Example 6 did not contain any flame retardant. Its flammability rating failed to reach B1, directly demonstrating that the synergistic effect of the flame retardant with the PVB and polypropylene adipate system is the guarantee for achieving high-level flame retardant performance.

[0164] Comparative Example 7, without the addition of KH550, showed a sharp drop in peel strength to 42 N / cm after hygrothermal aging, demonstrating that the silane coupling agent plays an indispensable role in maintaining long-term, reliable interfacial adhesion between PVB and glass and inorganic fillers.

[0165] Example 1 and Example 3 have the same PVB matrix and thickness. Example 3 used a higher content of functional filler and corresponding plasticizer, and the results showed that its infrared blocking rate, peel strength and durability reached the highest level, but haze and visible light transmittance were slightly sacrificed.

[0166] Example 2 has a halved thickness, meaning its energy absorption volume is halved, but the molecular weight of the PVB resin used in its skin layer A and core layer B is higher than that of Examples 1 and 3, resulting in the highest tensile strength. Although the infrared blocking rate is lower than that of Example 1 due to the halved thickness and reduced filler, it is still extremely high for a 0.38 mm film, demonstrating the high efficiency of the thermal insulation system of this invention. Although the penetration resistance is not as good as that of a 0.76 mm thick film, it is still excellent for a 0.38 mm specification, proving the effectiveness of the toughness design of this invention. The peel strength and damp heat resistance values ​​are lower because high molecular weight, low hydroxyl content PVB itself has poor adhesion.

[0167] In summary, the technical solution of this invention, through ingenious structural design and material blending, systematically solves the technical contradictions of PVB interlayer membranes in multiple dimensions such as high heat insulation, low haze, toughness, high durability and safety, and its inventiveness and practical value have been fully verified.

Claims

1. A high-barrier, low-haze PVB interlayer film, characterized in that, The intermediate membrane is an integrally formed A / B / A three-layer symmetrical structure, including two skin layers A and one core layer B; the thickness of skin layer A on one side is 0.06~0.12mm, and the thickness of core layer B is 0.26~0.52mm; The skin layer A is made from the following parts by weight of raw materials: First PVB resin: 100 parts; Triethylene glycol diisooctanoate: 25-30 parts; Polypropylene adipate: 2-8 parts; Core-shell structured ultraviolet absorber: 0.3~1.0 parts; Antioxidant: 0.05~0.2 parts; Alkalinity regulator: 0.3~0.8 parts; The core layer B is made from the following parts by weight of raw materials: Second PVB resin blend: 134~176 parts; Absorbing infrared blocking agent: 0.8~2.2 parts; Reflective infrared blocking agent: 0.3~1.2 parts; Polypropylene adipate: 10-24 parts; Dispersant: 0.35~1.1 parts; Silane coupling agent: 0.4~1.6 parts; Flame retardant: 3-10 parts; Core-shell structured ultraviolet absorber: 0.15~0.6 parts; The first PVB resin has a weight-average molecular weight of 53,000~93,000 g / mol and a hydroxyl content of 19 wt.%. The second PVB resin blend is a blend of ultra-high molecular weight PVB resin with a weight average molecular weight of 100,000~120,000 g / mol and a hydroxyl content of 13~19 wt.% and low molecular weight PVB resin with a weight average molecular weight of 16,000~24,000 g / mol and a hydroxyl content of 13~17 wt.%.

2. The high-barrier, low-haze PVB interlayer film according to claim 1, characterized in that, The mixing mass ratio of the ultra-high molecular weight PVB resin and the low molecular weight PVB resin is (2~18):(65~70).

3. The high-barrier, low-haze PVB interlayer film according to claim 1, characterized in that, The infrared blocking agent is cesium tungsten bronze.

4. The high-barrier, low-haze PVB interlayer film according to claim 1, characterized in that, The reflective infrared blocking agent is a hollow silica microsphere with a titanium dioxide shell on its surface, and the particle size is 1~2μm.

5. The high-barrier, low-haze PVB interlayer film according to claim 1, characterized in that, The core of the core-shell structured ultraviolet absorber is an organic ultraviolet absorber molecule, and the shell is an inorganic oxide.

6. The high-barrier, low-haze PVB interlayer film according to claim 1, characterized in that, The flame retardant is epoxy resin-coated ammonium polyphosphate.

7. The high-barrier, low-haze PVB interlayer film according to claim 1, characterized in that, The dispersant is polyvinylpyrrolidone.

8. A method for preparing a high-barrier, low-haze PVB interlayer film according to any one of claims 1 to 7, characterized in that, It is prepared by the following steps: (1) Preparation of the cortex A mixture: Take the first PVB resin, triethylene glycol diisooctanoate, polypropylene adipate, core-shell structure ultraviolet absorber, antioxidant, and alkalinity regulator and mix them evenly to obtain the skin layer A mixture. (2) Preparation of core layer B1 masterbatch: Low molecular weight PVB resin, ultra-high molecular weight PVB resin, infrared absorber, polypropylene adipate, dispersant, and silane coupling agent are granulated in a twin-screw extruder to obtain core layer B1 masterbatch. (3) Preparation of core layer B2 masterbatch: Low molecular weight PVB resin, ultra-high molecular weight PVB resin, reflective infrared blocking agent, polypropylene adipate, dispersant, silane coupling agent, core-shell structure ultraviolet absorber, and flame retardant are granulated in a twin-screw extruder to obtain B2 masterbatch. (4) Three-layer co-extrusion preparation First extruder: Add the skin layer A mixture; Second extruder: Add the mixed masterbatch of core layer B1 masterbatch and core layer B2 masterbatch; The distributor forms an initial A / B / A three-layer structure, which is extruded through the die, cooled and shaped, and then wound up to obtain a PVB intermediate film with high barrier properties and low haze.

9. The method for preparing a high-barrier, low-haze PVB interlayer film according to claim 8, characterized in that, The screw speed of the twin-screw extruder in step (2) is 200~300 rpm, and the screw speed of the twin-screw extruder in step (3) is 100~150 rpm.

10. The application of a high-barrier, low-haze PVB interlayer as described in any one of claims 1 to 7 in the preparation of automotive laminated glass or building energy-saving glass.

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