Micro gravure coating
The coating roller is a mesh rollerThe diameter is generally between 20mm and 50mm, so it is called micro gravure coating, which is a type of coatingDirection, contact type coating method, that is, the rotation direction of the micro coating roller is opposite to the feeding direction of the filmThe film is not pressed onto the coating roller by the pressure roller.
The traditional gravure coating method, whether it is direct coating or reverse coating, generally has back pressure rubber rollers and mesh rollers with a diameter roughly the same as the rubber.
Due to the film being pressed between the rubber roller and the mesh roller, there is a high possibility of wrinkles, cracks, and other defects appearing on the coating surface. The contact point between the two rollers can affect the coating quality due to mechanical and pneumatic factors.
And micro gravure coating is contact coating, which means there is no back pressure rubber rollerTherefore, some potential adverse factors caused by the pressure of the back pressure roller are eliminated.
Advantages：
1. Thin coatings can be applied to thin materials. Due to the absence of back pressure rollers, there are no defects such as offset printing or wrinkles on the coating surface.
2. As there is no back pressure roller, the edge of the film can also be coated with glue without worrying about the glue liquid being applied to the back pressure roller and affecting the coating.
3. Due to the light contact between the scraper and the mesh roller, the wear of both the scraper and the mesh roller is very small.
4. The micro concave roller has a small diameter and light weight, and can be easily replaced with different coating amounts. 5. Reverse coating can achieve a relatively smooth coating with even distribution of coating amount.
shortcoming：
1. The adhesive tank for micro gravure coating needs to keep the adhesive liquid overflowing during coating. The micro concave roller only comes into contact with the overflowing liquid, so it cannot fully utilize the adhesive liquid in the tank and cannot be recycled, resulting in a certain amount of waste. The amount of adhesive liquid waste is about 10KG.
If the micro concave roller is not cleaned thoroughly after use, it is easy to cause rusting of the micro concave roller, and rust removal is difficult.
3. Due to the exposure of the adhesive solution in the adhesive tank to the air during coating, dust and particles in the air are prone to fall into the adhesive tank during coating, which can have a certain impact on the quality of the coating.
4. The adhesive supply system for micro gravure coating is relatively complex, and cleaning and disassembly are difficult, often requiring 1-2 hours of time
Comma roller coating
The characteristic of comma roller coating is the combination of blade scraper and roller scraper.
The influence of adhesive thickness is smaller than that of blade scraper, and the coating thickness is easy to adjust, which can apply high viscosity adhesive. When the width is large, it can be adjusted horizontally.
Advantages：
1.The strength and hardness of the comma scraper are high, and the straightness error of the cutting edge is smallPneumatic fine-tuning mechanism can be used to adjust and control the position of the scraper, with high precision in coating amount control and adhesive scraping.
2. Thick coatings can be applied, and during coating, the adhesive flows from top to bottom between the scraper blade and the film, so the adhesive can be fully used without wasting it.
shortcoming：
1.The coating quality of comma roller coating is closely related to the operation of its various constituent unitsEspecially because the transmission ratio between the driving motor and the rotating pressure roller is difficult to adjust and control, it often leads to uneven coating.
2.Easy to have irregular horizontal or vertical stripesDuring coating, the adhesive solution is prone to flow out through the gap between the baffle and the transmission pressure roller, resulting in incomplete sealing. Additionally, manual stirring of the adhesive solution in the storage tank is required to ensure even distribution of the adhesive solution.
Slot Die Coating
Slot Die coating machine is a high-precision coating methodThe coating adhesive liquid is pressurized from the storage device to the nozzle through the supply pipeline, and the adhesive liquid is sprayed out from the nozzle, thereby transferring to the coated substrate.
Advantages：
1. Good coating effect, flexible control of coating amount through micro adjustment of coating scraper, high coating accuracy.
2. It can be applied in discontinuous mode, and the coating range can be freely adjusted without the need for a baffle, so there will be no stains caused by different edge thicknesses.
3. Cleaning and dismantling are relatively easy.
4. Helps to maintain a high level of cleanliness, and the overall flow channel of the adhesive can be sealed to prevent the entry of other pollutants.
shortcoming：
The structure of the entire Slot die coating head is relatively complex, requiring high processing accuracy for the glue roller, coating roller, traction roller, and scraper, resulting in higher costs compared to other coating methods.
Due to its high accuracy, it is difficult to use and operate in practice.
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