Three common precision coating methods

Micro gravure coating:

The coating roller is an anilox roller, with a diameter of generally Φ 20mm- Φ Between 50mm, it is called micro gravure coating, which is a directional and contact coating method. The rotation direction of the micro coating roller is opposite to the direction of the material film, and the material film is not pressurized by the pressure roller on the coating roller. Traditional gravure coating methods, whether direct or reverse coating, are used. Generally, there are back pressure rubber rollers and mesh rollers with roughly the same diameter as the rubber. Due to the material film being pressed between the rubber roller and the mesh roller, there is a high possibility of defects such as wrinkles and cracks appearing on the coating surface. The contact point between the two rollers during pressing can affect the coating quality due to mechanical, pneumatic, and other factors.

And micro gravure coating is a contact coating, which means there is no back pressure rubber roller. Therefore, some potential adverse factors caused by back pressure roller pressurization are eliminated.

Advantages:

1. A very thin coating can be applied to very thin materials. Due to the absence of back pressure rollers, there are no defects such as offset printing and wrinkles on the coated surface.

2. Due to the absence of a back pressure roller, the edges of the material film can also be coated with glue, without worrying about the glue 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 the scraper and mesh roller is very small.

4. The micro concave roller has a small diameter and light weight, and different coating amounts are applied, making it more convenient to replace the micro concave roller.

5. Reverse coating can achieve a relatively flat coating, with a uniform distribution of coating amount.

Disadvantages:

1. The glue storage tank for micro gravure coating needs to maintain a full state of glue during coating. The micro concave roller only comes into contact with the overflowing liquid, so it cannot

fully utilize the glue in the glue storage tank and cannot be recycled, resulting in a certain amount of waste. The amount of glue waste is about 10KG.

2. If the micro concave roller is not cleaned thoroughly after use, it is easy to cause rust on the micro concave roller and it is difficult to remove rust.

3. Due to the fact that the glue in the glue storage tank is exposed to the air during coating, dust and particles in the air during coating are prone to fall into the glue storage tank, which has a certain impact on the quality of the coating.

The glue supply system for micro gravure coating is relatively complex, making cleaning and disassembly difficult, often taking 1-2 hours.

Micro gravure coating application case:

Shading film, various optical films, materials for lithium batteries, various composite tapes, film films, protective films.

Comma roller coating:

The characteristic of comma roller coating is the combination of blade scraper and roller scraper. The influence of glue thickness is smaller than that of a blade scraper, and the coating thickness is easy to adjust. It can apply high viscosity glue, and can be adjusted horizontally when the width is large.

Advantages:

1. The strength and hardness of the comma scraper are high, and the straightness error of the blade is small. A pneumatic fine adjustment mechanism can be used to adjust and control the position of the scraper, resulting in high coating quantity control and glue scraping accuracy.

2. It can be applied with a thicker coating. When applying, the glue flows from top to bottom between the scraper blade and the material film, so the glue can be fully used and there is basically no waste of glue.

Disadvantages:

1. The coating quality of the comma roller coating is closely related to the operation of its various components, especially the transmission ratio between the driving motor and the rotating pressure roller, which is difficult to adjust and control, often resulting in uneven coating and the occurrence of horizontal or vertical irregular stripes. During coating, the glue is easy to flow out from the gap between the baffle and the transmission pressure roller, and the sealing is not complete enough. Moreover, during coating, manual labor is required to continuously stir the glue in the glue storage tank, To ensure the uniform distribution of the adhesive solution.

Application case of comma roller coating:

Various optical films, protective films, film films, matte soft packaging films.

Slot Die Coating:

The Slot Die coating machine is a high-precision coating method, where the coating adhesive is pressed to the nozzle through a supply pipeline from the memory, and the adhesive is sprayed out from the nozzle, thereby transferring to the coated substrate.

Advantages:

1. The coating effect is good, and the coating amount is flexibly controlled through the micro adjustment of the coating scraper, resulting in high coating accuracy.

2. It can be applied in a discontinuous mode, and the coating range can be freely adjusted without the need for a baffle, which will not cause stains caused by different edge thicknesses.

3. Cleaning and dismantling are relatively easy.

4. It helps to maintain a high level of cleanliness, and the overall flow channel of the glue can be sealed to prevent the entry of other pollutants.

Disadvantages:

1. The structure of the entire Slot-die coating head is relatively complex, requiring high processing accuracy of the glue roller, coating roller, traction roller, and scraper, therefore the cost is higher than other coating methods.

2. Due to its high accuracy, it is difficult to use and operate in practice.

Slot die coating application case:

Optical film, special paper.