Main production process and structure of polarizing film coating machine
2019-03-11
The requirements of polarizing film coating machine are similar to those of other optical film coating production lines, which require precise manufacturing and accurate control. This paper briefly introduces the market situation and structure of polarizing film, expounds the main production process and structure composition of polarizing film coating, and puts forward relevant views on how to reduce the investment cost of polarizing film coating machine and the localization of equipment.
Summary
The production of polarizing film is divided into three processes: TAC surface treatment, PVA stretching and bonding after coating. In this paper, the optical coating machine used for coating and bonding of separated film is described.
Corona device
The use of corona device is to treat the surface of the coated side by electric shock according to the need, so that it has higher adhesion. The principle is to use high frequency and high voltage corona discharge on the surface of treated plastics to produce low temperature plasma, which can cause free radical reaction on the surface of plastics, resulting in crosslinking, roughening of the polymer surface and increasing its wettability and adhesion to polar solvents.
coating head
Coating head is the core of the whole coating production line. At present, polarizing film coating mainly includes COMMA KNIFE (comma scraper) and SLOT DIE (slit die extrusion coating).
The suitable coating thickness of COMMA KNIFE is 18-100 micron, and the viscosity of the coating solution is high. The prominent advantage of COMMA KNIFE is that it is easy to change the coating width and the glue feeding system is relatively simple. However, there is a large area of exposure of coating liquid, so it is necessary to ensure the cleanliness of the coating head.
SLOT DIE slit coating is a kind of anticipated quantity coating method, that is to say, the amount of coating depends on the ratio of the amount of liquid input to the speed of base material operation, and can be set accurately in advance. Usually, high precision non-pulse metering pump is used to transport the amount of coating liquid. SLOT DIE coating can be divided into two ways: direct contact of back roll and tension control of base material. Polarizing film coating mainly adopts direct contact of back roll. This kind of coating has a wide thickness range of about 3-300 um, which can meet different application requirements and is suitable for production speed from low to high. The coating accuracy is affected by the flatness of the back roll itself and the runout of the bearing. Because the coating gap is very small, it is very sensitive to the change of the thickness of the substrate and the influence of foreign bodies on the surface. During the production process, it is difficult to change the coating liquid varieties, so it needs to be cleaned repeatedly with solvent.
The thickness errors of the two coatings can be controlled within 1 micron after drying. SLOT DIE slit coating machine has higher precision and high cost, and needs to be equipped with perfect rubber supply system.
Summary
The production of polarizing film is divided into three processes: TAC surface treatment, PVA stretching and bonding after coating. In this paper, the optical coating machine used for coating and bonding of separated film is described.
Corona device
The use of corona device is to treat the surface of the coated side by electric shock according to the need, so that it has higher adhesion. The principle is to use high frequency and high voltage corona discharge on the surface of treated plastics to produce low temperature plasma, which can cause free radical reaction on the surface of plastics, resulting in crosslinking, roughening of the polymer surface and increasing its wettability and adhesion to polar solvents.
coating head
Coating head is the core of the whole coating production line. At present, polarizing film coating mainly includes COMMA KNIFE (comma scraper) and SLOT DIE (slit die extrusion coating).
The suitable coating thickness of COMMA KNIFE is 18-100 micron, and the viscosity of the coating solution is high. The prominent advantage of COMMA KNIFE is that it is easy to change the coating width and the glue feeding system is relatively simple. However, there is a large area of exposure of coating liquid, so it is necessary to ensure the cleanliness of the coating head.
SLOT DIE slit coating is a kind of anticipated quantity coating method, that is to say, the amount of coating depends on the ratio of the amount of liquid input to the speed of base material operation, and can be set accurately in advance. Usually, high precision non-pulse metering pump is used to transport the amount of coating liquid. SLOT DIE coating can be divided into two ways: direct contact of back roll and tension control of base material. Polarizing film coating mainly adopts direct contact of back roll. This kind of coating has a wide thickness range of about 3-300 um, which can meet different application requirements and is suitable for production speed from low to high. The coating accuracy is affected by the flatness of the back roll itself and the runout of the bearing. Because the coating gap is very small, it is very sensitive to the change of the thickness of the substrate and the influence of foreign bodies on the surface. During the production process, it is difficult to change the coating liquid varieties, so it needs to be cleaned repeatedly with solvent.
The thickness errors of the two coatings can be controlled within 1 micron after drying. SLOT DIE slit coating machine has higher precision and high cost, and needs to be equipped with perfect rubber supply system.