Detailed explanation of the three major precision coating methods

Microgravure coating

The coating roller is an anilox roller, the diameter is generally between Φ20mm-Φ50mm, so it is called micro gravure coating, it is a directional, contact coating method, that is, the rotation direction of the micro coating roller is opposite to the direction of the material film, and the material film is not pressurized on the coating roller by the pressure roller.

Conventional gravure coating methods, whether direct or reverse coating, generally have a back-pressure rubber roller and a anilox roller with roughly the same diameter as the rubber.

Because the film is pressed between the rubber roller and the anilox roller, it is very likely that there will be wrinkles, cracks and other defects on the coating surface, and the contact point of the two rollers will have an impact on the coating quality due to factors such as machinery and air pressure.

Microgravure coating, on the other hand, is a contact coating, which means that there are no rubber rollers with back pressure, so some of the potential disadvantages caused by the pressurization of the back pressure rollers are eliminated.

Pros:

1. It is possible to apply a very thin coating to a very thin material. Since there is no back pressure roller, there are no defects such as offset printing and wrinkles on the coating surface.

2. Since there is no back pressure roller, the edge of the film can also be coated with glue, without worrying about the glue being applied to the back pressure roller and affecting the coating.

3. Since the scraper lightly touches the anilox roller, the wear of the scraper and the mesh roller is very small.

4. The diameter of the micro-concave roller is small, the weight is light, and the coating amount is different and it is more convenient to replace the micro-concave roller. 5. Reverse coating can obtain a relatively flat coating, and the coating amount is evenly distributed.

Cons:

1. The glue storage tank of micro gravure coating needs to be kept in a state of overflow when coating, and the micro concave roller is only in contact with the overflowing liquid, so the glue in the rubber storage tank cannot be fully utilized, and it cannot be recycled, so it causes a certain amount of waste, and the amount of glue waste is about 10KG.

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

3. Because the glue in the rubber tank is exposed to the air during coating, the dust and particles in the air are easy to fall into the rubber tank during coating, which has a certain impact on the quality of coating.

4. The glue supply system of micro gravure coating is more complex, and it is difficult to clean and disassemble, often taking 1-2 hours

Comma roller coating

Comma roll coating is characterized by a combination of blade and roll blade.

The effect of glue thickness is less than that of blade scrapers, and the coating thickness is easy to adjust, enabling the application of high-viscosity glue. When the width is large, it can be adjusted horizontally.

Pros:

1. The comma scraper has high strength and hardness, and the straightness error of the cutting edge is small, and the pneumatic fine-tuning mechanism can be used to adjust and control the position of the scraper, and the coating amount control and scraping accuracy are high.

2. Thicker coating can be applied, and when coating, the glue flows from top to bottom between the scraper edge and the material film, so the glue can be fully used, and there is basically no waste of glue.

Cons:

1. The coating quality of the comma roller coating has a great relationship with the operation of each component unit, especially for the transmission ratio between the drive motor and the rotating pressure roller is difficult to adjust and master, which often causes uneven coating.

2. It is easy to appear transverse or longitudinal irregular stripes, when coating, the glue is easy to flow out in the gap between the baffle plate and the transmission pressure roller, the sealing is not complete, and when coating, manpower is required to continuously stir the glue of the glue tank, so as to ensure the uniform distribution of the glue.

Slot-Die Coating

The Slot Die coater is a high-precision coating method in which the glue is pressed by the memory through the supply line to the nozzle, and the glue is sprayed from the nozzle and transferred to the substrate of the coating.

Pros:

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

2. It can coat the discontinuous mode, and the coating range can be adjusted freely, without the need for baffles, and there will be no stains caused by different edge thicknesses.

3. It is easier to clean and disassemble.

4. Helps to maintain a high level of cleanliness, the channel through which the glue flows as a whole can be sealed to prevent the ingress of other contaminants.

Cons:

1. The structure of the whole Slot-die coating head is more complex, which requires high processing accuracy of gluing rollers, coating rollers, traction rollers and scrapers, so the cost is higher than other coating methods.

2. Due to the high precision, it is difficult to use and operate in practice.