polyvinyl butyral

Since the late 1930s, polyvinyl butyral (PVB), a type of thermoplastic resin, has been key to making laminated glass. Laminated glass consists of one or more layers of PVB film (the interlayer) between two or more pieces of glass, bonded together using heat and pressure. This structure endows the finished glass with a range of unique properties, making it a crucial safety and functional material in the automotive industry and modern construction.   1. Chemical Basis and Unique Properties of PVB Resin 1.1 Structure and Synthesis PVB resin is a synthetic polymer obtained from polyvinyl alcohol (PVA) and butyral through an acetalization reaction. Its molecular chain contains three main functional groups: Butyral group: Responsible for providing the polymer with hydrophobicity, elasticity, and solubility. Hydroxy group: Maintains the polymer's strong adhesion to glass surfaces, heat resistance, and compatibility with plasticizers. Vinyl acetate group:，Usually present in small amounts, it has a fine-tuning effect on the glass transition temperature (Tg) and processing properties of PVB. This unique structure endows PVB with a range of ideal properties for laminated glass applications. 1.2 Key Physical Properties As the interlayer in laminated glass, PVB film must possess the following core physical properties: High Adhesion Strength: Strong adhesion to the glass surface ensures that glass fragments adhere firmly to the film upon impact. Excellent Elasticity and Toughness: Ability to absorb impact energy and effectively prevent penetration, forming the physical basis for the safety of laminated glass. Optical Transparency: Extremely high light transmittance in the visible light range, without affecting driver visibility or building lighting. Aging Resistance: Maintaining its mechanical and optical properties even under harsh environments such as ultraviolet radiation, humidity, and temperature variations.     2. Core Applications and Functions in Automotive Glass Automotive glass is one of the earliest and most important application markets for PVB resin. PVB plays a dual role in automotive windshields, providing both safety and functionality. CCP PVB B-18FS, combined with plasticizer 3GO and additives, can be extruded to produce various PVB interlayer films for architectural and automotive applications. 2.1 Collision Safety and Fragment Retention This is the most critical role of PVB in automotive applications. In a vehicle collision, the windshield shatters, but the PVB interlayer can: Prevent Penetration: The windshield is designed to take in impact energy. This stops things like stones from getting through the glass into the car. Plus, it keeps passengers inside the car and protects them from head injuries if they hit the glass. Fragment Retention: Firmly adhere to broken glass, preventing sharp fragments from flying and causing secondary injuries to passengers. 2.2 Noise Reduction and Sound Insulation Performance Modern cars need to be more comfortable to drive. PVB films, mostly those made in a specific way, are good at quieting high-frequency vibrations. This cuts down on wind and road noise. For instance, Changchun PVB B-17HX is made with certain plasticizers and a specific molecular weight to improve its damping abilities. It works very well for car side windows and sunroofs, where better sound insulation is needed.   3. Applications of PVB Resin in Architectural Glass Laminated glass is used in a lot of construction projects. You can find it in curtain walls, skylights, interior walls, and railings. The application of PVB resin must adapt to more stringent requirements for structural strength, durability, and climate change mitigation. 3.1 Structural Safety and Disaster Resistance The main function of laminated glass in architecture is to provide structural integrity and disaster resistance. Storm and Earthquake Resistance: In severe weather, like hurricanes, typhoons, or earthquakes, PVB laminated glass can still hold its structure even if it breaks. This helps keep people and property inside safe, because the glass doesn't collapse or fall apart. Theft and Explosion Protection: Thickened multi-layer PVB laminated glass (usually a composite structure of multiple layers of PVB and glass) has extremely high impact resistance. It can effectively resist the impact of blunt objects or gunshots and is widely used in high-security locations such as banks, jewelry stores, and museums. In the shock wave of an explosion, the PVB layer can absorb energy, preventing glass shards from injuring people. 3.2 Energy Saving, Environmental Protection, and Aesthetic Design Technological advancements in PVB films have also made them part of building energy-saving solutions. Solar Control PVB: PVB films containing special additives or dyes can regulate the transmittance and reflectance of sunlight, reducing heat entering the interior (lowering U-value and SC value), thereby reducing air conditioning energy consumption. Colors and Patterns: PVB films can be customized in a variety of colors and can even be embedded with patterns or textiles, providing architects with a wealth of facade design and aesthetic choices to meet the complex needs of modern architecture for light, privacy, and appearance. 3.3 Durability and Long-Term Performance Architectural glass must withstand decades of outdoor exposure. PVB resin possesses excellent durability: Aging Resistance: High-quality PVB films have good resistance to ultraviolet rays and moisture, ensuring that laminated glass will not yellow or delaminate during long-term use. Edge Sealing: The edge bonding strength between PVB and glass is key to preventing moisture and air penetration, which is essential for maintaining the transparency of laminated glass and preventing internal fogging.   As the automotive and construction industries increasingly demand higher standards of safety, environmental protection, and functionality, PVB resin technology is constantly evolving: ♦ Competition and Integration of Innovative Materials While PVB remains the mainstream material, new interlayer materials such as ionic polymers (e.g., SGP/Surlyn) are competing in applications requiring high structural strength and rigidity, particularly in high-rise buildings. The future trend may involve the composite use of PVB with other polymers to achieve a superior performance balance. ♦ Intelligentization and Integration Future automotive and architectural glass will be more intelligent, with PVB films serving as carriers for functional materials: Thermal Management and Electrical Heating: PVB layers can integrate micro-wires or transparent conductive materials for defogging, defrosting, or intelligent dimming of glass. Integrated Antennas and Sensors: Integrating vehicle antennas or various environmental sensors into the PVB film layer achieves high functional integration and aesthetic optimization. ♦ Sustainable Development Under environmental pressures, developing PVB resins synthesized from renewable resources or bio-based raw materials, and improving PVB recycling technologies, will be significant challenges and development directions for the industry.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com  

The lifespan of solar panels depends a lot on the materials used to seal them. That's why researchers spend a lot of time studying these materials. A comparative analysis of the aging resistance of the four mainstream encapsulation films currently on the market: Ethylene Vinyl Acetate (EVA), POE, EPE, and PVB. PolyVinyl Butyral Film (PVB film) exhibits excellent aging resistance, while EVA film exhibits good initial performance but relatively poor aging resistance.     1. Four Mainstream Encapsulation Films EVA film: Made from ethylene-vinyl acetate copolymer resin, it is the largest market share photovoltaic module encapsulation material. Vinyl acetate groups are introduced through high-pressure polymerization. The vinyl acetate content affects film performance and is typically between 28% and 33%. EVA film technology is mature and relatively low-cost. As a photovoltaic module encapsulation film, it offers the following advantages: Strong adhesion to photovoltaic glass, solar cells, and backsheets Good melt flowability and low melting temperature High light transmittance Excellent flexibility, minimizing damage to solar cells during lamination Excellent weather resistance   POE film: A random copolymer elastomer formed from ethylene and 1-octene, it features a low melting point, a narrow molecular weight distribution, and long chain branches. In the ethylene-octene copolymer system, octene units can be randomly attached to the ethylene backbone, resulting in excellent mechanical properties and light transmittance.Excellent moisture vapor barrier properties: Its moisture vapor transmission rate is approximately 1/8 that of EVA. Its stable molecular chain structure results in a slow aging process, providing better protection for solar cells from moisture corrosion in high-temperature and high-humidity environments and enhancing PID resistance in solar modules.Excellent weather resistance: The molecular chain contains no hydrolyzable ester bonds, preventing the generation of acidic substances during aging.   EPE Co-extruded Film: This encapsulation film was developed to address the application challenges of POE films. POE films are prone to additive precipitation during lamination, resulting in slippage during use and affecting product yield. Therefore, EVA and POE are co-extruded in multiple layers to create EVA/POE/EVA multilayer co-extruded films.This film combines the advantages of both materials: it possesses the water barrier and PID resistance of POE with the high adhesion of EVA.Process control is challenging: Polyolefin elastomers are non-polar molecules, while ethylene-vinyl acetate copolymers are polar molecules. The two resins exhibit significant differences in cross-linking reactivity, melt viscosity, and shear melt heating rate, making it difficult to effectively control quality through a simple co-extrusion process.   PVB Film: This film offers significant advantages in photovoltaic module encapsulation, particularly for building-integrated photovoltaic (BIPV) modules. This thermoplastic polymer is formed by the acid-catalyzed condensation of polyvinyl alcohol (PVA) generated by the hydrolysis or alcoholysis of polyvinyl acetate and n-butyraldehyde. It is recyclable and reprocessable, and does not require a cross-linking reaction.Strong Adhesion and Mechanical Properties: It exhibits strong adhesion to glass and high mechanical strength.Excellent Aging Resistance: It exhibits exceptional environmental aging resistance, making it more resilient for outdoor use and capable of lasting up to four years without compromising performance. Its adhesion to glass and impact resistance are superior to those of EVA film, and its aging resistance is also superior to that of EVA film.   2. Aging Resistance - UV Accelerated Aging Test The UV accelerated aging test verifies atmospheric light aging resistance. After lamination, the prepared materials are placed in a UV aging chamber under controlled test conditions. After aging, the peel strength and yellowing index of the film against glass are measured. UV radiation damages the film's adhesive properties, but the effect is less severe than in high temperature and high humidity environments. EVA exhibits significant yellowing after UV irradiation. Peel Strength Change: UV irradiation does affect the peel strength between the film and glass to some extent, but the effect is less pronounced than in high-temperature, high-humidity environments. Different films exhibit different peel strength change trends after UV irradiation. For example, samples 1# (EVA), 2# (POE), 3# (EPE), and 4# Polyvinyl Butyral (PVB) all show a decrease in peel strength after UV irradiation, but the degree of decrease varies. Yellowing Index Change: EVA exhibits significant yellowing after UV irradiation. This is because residual crosslinkers in the EVA decompose under the influence of light, generating reactive free radicals that react with the antioxidant (UV absorber) to form chromophores. The yellowing index of other films also changes after UV irradiation, but to a lesser extent than that of EVA.   3. Aging Resistance - High-Temperature, High-Humidity Aging Test The laminated samples were placed in a constant temperature and humidity chamber at a temperature of (85±2)°C and a relative humidity of 85%±5% for 1000 hours. The peel strength of all four samples against glass decreased after hygrothermal aging. PVB exhibited superior hygrothermal aging resistance, while EPE fell between EVA and POE. EVA was more susceptible to yellowing under high temperature and high humidity conditions. Peel Strength Change: The peel strength of samples 1#, 2#, 3#, and 4# against glass decreased after hygrothermal aging, and this continued to decline with increasing hygrothermal aging time. Yellowing Index Change: The yellowing index of all samples increased with increasing hygrothermal aging time, with EVA showing the largest increase, indicating that EVA is more susceptible to yellowing under high temperature and high humidity conditions.   4. Aging Resistance - Humidity-Freeze Aging Test Laminated specimens were placed in a temperature-humidity cycling test chamber. The cycle conditions were characterized by specific temperature and humidity variations, as shown in the figure below. The number of cycles was 20. Peel Strength Change: As shown in the figure, the humidity-freeze cycle had little effect on the peel strength between films 1#, 2#, 3#, and 4 and the glass. The peel strength of the four films remained relatively stable during the humidity-freeze cycle, with no significant decrease. Yellowing Index Change: The four films showed low yellowing after the humidity-freeze cycle, demonstrating that they maintain high performance despite frequent temperature fluctuations and exhibit good resistance to yellowing. Their optical properties remained relatively stable in environments with high humidity and large temperature fluctuations.   Mechanical tests showed that PVB has the best properties, while EVA is mechanically stronger than POE, with EPE in between. Overall, PVB film resists aging best, while EVA is good at first but ages faster. EVA is still popular because it's affordable. As tech gets better, POE and EPE will likely become more common alongside EVA, giving more choices for sealing solar panels.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com