Comparison of four common precision coating methods

There are many types of products produced by coating processing, from household products to cutting-edge technology, there is a shadow of coating technology, especially when producing high-precision coating products, the coating process technology needs to be involved in high quality, our focus here Introduce the characteristics of 3 common precision coating processes for comparison, for reference by coating engineers.

Substrates for precision electronic products are developed through coating technology, which covers a lot of technologies. From the key point of view of technology, the importance is as follows:

• Quality and performance (Formulation) 25%

• Coating technology (Coating) 35%

• Transfer technology (Know-how) 25%

• Equipment technology (Equipment) 15%

1. Micro-gravure coating The micro-gravure coating roller is an anilox roller, and its diameter is generally between Φ20mm-Φ50mm, so it is called micro-gravure coating. It is a directional, contact-type coating method, that is, micro-coating The rotation direction of the roller is opposite to the feeding direction of the material film, and the material film is not pressed against the coating roller by the pressing roller. The traditional gravure coating method, whether it is direct coating or reverse coating, generally has a back pressure rubber roller and an anilox roller with roughly the same diameter as the rubber. Since the material film is pressed between the rubber roller and the anilox roller, wrinkles, cracks and other defects are likely to appear on the coating surface. The contact point of the two rollers will affect the coating quality due to factors such as mechanical and air pressure. While micro-gravure coating is contact coating, contact coating means that there is no back pressure rubber roller, therefore, some potential disadvantages caused by the pressure of the back pressure roller are eliminated.

Advantages of microgravure

• It is possible to apply very thin coatings to very thin materials. Because there is no back pressure roller, there are no defects such as offset printing and wrinkles on the coating surface;

•Because there is no back pressure roller, the edge of the material film can also be coated with glue, without worrying about the glue liquid being applied to the back pressure roller and affecting the coating;

• Since the scraper lightly touches the anilox roll, the abrasion of the scraper and the anilox roll is very small;

•The micro-gravure roller is small in diameter and light in weight. It is easy to replace the micro-gravure roller with different coating amounts;

• Reverse coating can obtain a relatively smooth coating, and the coating amount is evenly distributed.

Disadvantages of micro intaglio

•The glue storage tank for micro-gravure coating should keep the glue overflowed during coating. The micro-gravure roller only contacts the overflowing liquid phase, so the glue in the glue storage tank cannot be fully utilized, and it cannot be fully utilized. Recycling, thus causing a certain amount of waste, the amount of glue wasted is about 10KG;

• If the micro-concave roller is not cleaned after use, it will easily cause the micro-concave roller to rust, and it will be difficult to remove rust;

• Since the glue in the glue storage tank is exposed to the air during coating, dust and particles in the air will easily fall into the glue storage tank during coating, which will affect the coating quality to a certain extent;

• The glue supply system of micro-gravure coating is more complicated, and it is difficult to clean and disassemble, and it usually takes 1-2 hours.

Application of micro intaglio

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

Two, comma doctor roll coating

The characteristic of comma roll coating is the combination of blade blade and roll blade. The thickness of the glue has less influence than the blade scraper, the coating thickness is easy to adjust, and it can be coated with high-viscosity glue. When the width is large, it can be adjusted horizontally.

Comma coated a bit

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

• Thicker coatings can be applied. When coating, the glue flows from top to bottom between the doctor blade and the material film, so the glue can be fully used, and there is basically no waste of glue.

Disadvantages of comma roll coating

• The coating quality of comma roll coating has a great relationship with the operation of its various components, especially the transmission ratio between the drive motor and the rotating press roller is difficult to adjust and master, which often results in uneven coating and prone to horizontal or vertical When coating, the glue will easily flow out in the gap between the baffle and the transmission roller, and the sealing is not complete. And when coating, it needs manpower to continuously stir the glue in the glue tank. Ensure the uniform distribution of glue. The application of comma roll coating is various optical films, protective films, film films, matt flexible packaging films.

3. Slot-Die Coating

The slit extrusion coater is a common high-precision coating method. The coating glue is pressed from the storage to the nozzle through the supply pipe, and the glue is ejected from the nozzle, thereby transferring to the coated On the substrate.
Advantages of gap coating

•The coating effect is good, the coating amount can be flexibly controlled by the micro-motion adjustment of the coating blade, and the coating precision is high;

• It can be coated in discontinuous mode, and the coating range can be adjusted freely, no baffle is needed, and there will be no stains caused by different edge thicknesses;

• Easy to clean and disassemble;

•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 contaminants.

Disadvantages of slit extrusion coating

• Part of the structure of the entire Slot-die coating head is more complex, requiring high processing accuracy of the gluing roller, coating roller, traction roller and doctor blade, so the cost is higher than other coating methods;

• Due to the high accuracy, it is difficult to actually use and operate.

Application of gap extrusion coating

High-end films such as high-end optical films, window films, and specialty papers.

4. Roll-to-Roll Precision Coating

The so-called Roll-to-Roll Precision Coating technology can be applied to various industries such as IC, PCB, optoelectronics, people’s livelihood, and medical treatment, ranging from general products (such as stationery tape) to medical tape (beauty, healing tape) ) To electronic tapes (IC cutting, PCB solder mask), and photoelectric tapes (optical adhesives for LCD), etc., are all products developed using precision coating technology platforms.

Company Profile

Nanjing Sumino Precision Machinery Co., Ltd. is a high-tech enterprise integrating scientific research, production and sales. It has always adhered to the business philosophy of integrity, equality, and customer benefits. In order to better improve the quality of equipment, it has entered a more professional and standardized Production track. We have established independent research and development technologies for seven categories of equipment including plastic sheet material, casting, bi-stretching, non-woven non-woven meltblown cloth, laminating film composite, recycled granulation environmental protection recycling system and coating machine manufacturing system. The center and production department provide a full set of professional technical solutions to meet the special needs of each customer. Among them, the biaxially oriented film manufacturing system includes: BOPP biaxially oriented film manufacturing system, PVC biaxially oriented shrink film production line, PET biaxially oriented film production line, BOPA biaxially oriented film production line, BOPA biaxially oriented film production line, etc.

Company Address: No. 11, Kaifeng Road, Moling Street, Jiangning District, Nanjing City, Jiangsu Province