The optical properties of polarizer include polarizability, transmittance and hue, and the other include anti-ultraviolet properties and transmittance, total reflectance and diffuse reflectance of semi-transparent polarizer film. In the use of general LCD products, the higher the performance index of polarization and transmittance, the better. The higher the polarization and transmittance, the higher the display efficiency of LCD display devices and the lower the relative energy consumption. But for conventional iodine-dyed polarizer products, polarization and transmittance are contradictory. The higher the polarization, the lower the transmittance, and also subject to tone constraints. Therefore, the polarization of ordinary polarizer products is between 90% and 99%, and the transmittance is between 41% and 44%. Guangdong Fudi Rihe Polarizing Devices Co., Ltd. produces "Fudi" brand polarizer universal PLN products with polarizer polarizer polarizer polarizer polarizer polarizer polarizer of 97% and transmittance of 43%, while durable and high contrast PMN products with polarizer of 99.9% and transmittance of 42%. The hue index is mainly to satisfy people's visual habits, and requires that the hue deviation of polarizer products be small to ensure the consistency of the appearance hue of LCD final products. This is mainly marked by the color coordinate parameters L, a, B of polarizer products and their control tolerance range. Generally, the smaller the control tolerance range, the better.
The durability of polarizer includes four technical indexes: high temperature resistance, humidity resistance, low temperature resistance and cold and heat shock resistance. The most important one is the humidity and heat resistance. High temperature resistance refers to the working conditions of the polarizer under constant baking temperature. At present, according to the technical level of the polarizer, the polarizer is generally divided into three types: working temperature is 70 500HR; medium durable type: working temperature is 80 500HR; high durable type: working temperature is above 90 500H. The technical index of humidity and heat resistance refers to the humidity and heat resistance performance of polarizer under constant temperature and humidity conditions. It is also generally divided into three technical grades: general type: humidity and heat working conditions of 40 90% RH 500HR; medium durability type: humidity and heat working conditions of 60 90% RH 500HR; and high durability type: humidity and heat working conditions of 70 95% RH 500HR. Because PVA film, iodine and iodide are the basic materials of polarizing film, which are easy to hydrolyze. At the same time, pressure sensitive adhesives used in polarizing film are easy to deteriorate under high temperature and humidity. Therefore, the most important technical indexes of the durability of polarizing film are high temperature and humidity heat resistance. If the indexes of high temperature and humidity heat resistance pass, other durability indexes are usually all the same. No problem.
The bonding characteristics of polarizer mainly refer to the properties of polarizer pressure sensitive adhesives, which generally include the peeling force between pressure sensitive adhesives and glass substrates, the peeling force between pressure sensitive adhesives and peeling films, the peeling force between polarizer protective films and polarizers, and the bonding durability of pressure sensitive adhesives. The peeling force between pressure sensitive adhesives and glass substrates is also called the bonding strength of adhesives, which is the most important bonding characteristic index of LCD polarizer products. This technical index is usually measured by EIAJ-ED-2521A standard of Japan Electronics Machinery Industry Association. It is expressed in g/25mm. Usually, the peeling force of LCD polarizer pressure-sensitive adhesives on glass substrates is more than 500 g/25mm, while the practical upper limit is generally less than 1000g/25mm. Practical examples show that when the peeling force of the adhesives on the glass substrates is less than 500 g/25mm, the phenomenon of automatic peeling and warping of the polarizer after bonding on the surface of the glass screen will occur.
The technical indicators of the exterior performance of the polarizer mainly refer to the surface smoothness and the number of appearance defects of the polarizer products. These technical indicators mainly affect the utilization rate of the polarizer products in patching. These technical indicators in the polarizer industry usually have relatively consistent technical requirements, generally for each polarizer product (500 *1000) 15 points less than 150 microns. Because the final appearance inspection of polarizer products is manual visual inspection, the distribution of appearance defects will be discrete in the mass production process of polarizer products. For this reason, each polarizer manufacturer adopts a certain difference between internal control specifications and delivery specifications to ensure delivery quality standards. However, it should be noted that 150 micron is close to the minimum limit of human visual discrimination, especially in the industrial mass production process, inspectors will also produce visual fatigue in long-term operation, so the 150 micron defect point inspection standard is more reasonable and credible.
The Main Factors Affecting the Performance Index of LCD Polarizer
The main factors affecting the performance of polarizer are related to the basic performance index of polarizer.
The main factors affecting the optical properties of polarizers include the selection of polarizer materials, dyeing materials, dyeing of polarizer films, the selection of stretching conditions and the limitation of equipment capacity. These are all related to the core technology of polarizer production, so polarizer production enterprises are very careful about the choice of these materials and process conditions, and generally will not be easily changed. Once the products of the polarizer manufacturer are approved by the customers, the polarizer manufacturer will take strict production quality management measures to ensure the stability of the optical properties of the polarizer products.
The technical index of durability of polarizer products actually includes two aspects: durability of polarizer film and durability of pressure sensitive adhesives. The main factors affecting the durability of polarizing film include the selection of basic materials, dyeing materials, dyeing, stretching and composite process conditions. Generally speaking, the greater the molecular weight of PVA film and the higher the draw ratio, the better the durability of polarizing film, and vice versa. At the same time, the better the colority of polarizing film in the production process and the stronger the anti-hydrolysis ability of dyes used, the better the durability of polarizing film. Therefore, the durability of dye polarizing film is much better than that of iodine dyeing polarizing film products. The main factors affecting the durability of pressure sensitive adhesives include the selection of binder formulation, binder solvent, binder mixing process conditions, drying process conditions and storage conditions. It should be noted that the durability index of adhesives is a comprehensive index, its influence is multifaceted, and this is another core technology of polarizer production. Generally, after determining the process conditions of adhesives, polarizer manufacturers will not easily change and have strict process quality management requirements, otherwise they will easily cause bad batch products.
The main factors affecting the appearance of polarizer are also various. There are mainly: the environment purification conditions of polarizer production, the material selection of polarizer production, the equipment conditions of polarizer production, the technological process and formula of polarizer production, the packaging, storage and transportation conditions of polarizer, as well as the storage environment and processing methods of polarizer when used by customers. In short, polarizer is a very "delicate" product, which must be carefully preserved and used, otherwise it is easy to cause surface pits, black spots and warpage and other surface defects.