I. Dip Coating

Dip coating is one of the earliest technologies in the coating industry. The principle involves completely immersing the substrate into the coating liquid, utilizing the substrate's porosity to adsorb the coating, followed by removing excess liquid through squeezing or drying.

Core Advantages: Simple equipment, low cost, suitable for porous substrates.

Typical Applications: Printed circuit board paper, moisture-proof paper (impregnated with vinylidene chloride emulsion), resin-impregnated fabrics.

II. Air Knife Coating

Air knife coating employs a high-speed airflow (air knife jet) to blow away excess coating from the substrate surface, thereby controlling the coating thickness. This method achieves relatively thin and uniform coatings and has certain requirements for coating viscosity.

Core Advantages: Excellent coating uniformity, suitable for thin coatings.

Typical Applications: High-grade art printing paper, carbonless copy paper.

III. Knife Coating

Knife coating is currently the most common technology in the coating industry. It uses a metal or plastic blade to scrape off excess coating from the substrate surface, allowing precise control over coating thickness.

Core Advantages: Simple operation, strong adaptability, capable of handling high-viscosity coatings.

Typical Applications: Solvent-based pressure-sensitive adhesive coating (for adhesive products like tapes, labels, films).

IV. Rod Coating

Rod coating (also known as wire rod coating) utilizes a rotating metal rod/wire bar to remove excess coating. It is suitable for low-viscosity and low-coating-weight scenarios. The thickness of the coating is directly determined by the diameter of the rod; changing the rod adjusts the parameters.

Core Advantages: Compact equipment, easy operation, strong controllability of coating thickness.

Typical Applications: Water-based coatings, thin coatings on paper.

V. Roller Coating

Roller coating is a multi-roller cooperative coating method, involving at least a coating roller (transfers the coating) and a metering roller (controls the amount of coating). Common types include two-roll coating, three-roll coating, and reverse roll coating (where the coating roller moves opposite to the substrate direction).

Core Advantages: Suitable for high-viscosity coatings, high coating efficiency.

Typical Applications: Plastic film coatings, metal foil coatings.

VI. Gravure Coating

Gravure coating uses an engraved roll (patterned roll/micro-gravure roll) to transfer the coating – the coating contained in the engraved cells is transferred to the substrate surface. The size and density of the cells determine the coating weight.

Core Advantages: Excellent uniformity for thin coatings, suitable for low-viscosity coatings.

Typical Applications: Food packaging films, insulating coatings for electronic components.

VII. Slot Die Coating

Slot die coating is a representative technology for precision coating. The coating liquid enters the coating die through a sealed conduit and is extruded uniformly onto the substrate surface through a narrow slot. As the die is non-contact (or minimal contact) with the substrate, it achieves extremely high coating precision.

Core Advantages: High coating precision (can reach micron-level), no waste.

Typical Applications: Hot melt coating, precision optical films, lithium battery electrode coating.

VIII. Multi-Layer Slide Coating

Multi-layer slide coating involves different coating liquids simultaneously flowing out through multiple slot dies. The liquids flow down an inclined plane forming a "slide" or "curtain flow," ultimately forming a multi-layer composite coating on the substrate surface.

Core Advantages: Completes a multi-layer structure in a single pass, high efficiency.

Typical Applications: Multi-layer photosensitive materials (e.g., X-ray film, photographic film).

IX. Curtain Coating

Curtain coating is a typical non-contact coating method. The coating liquid flows from the die to form a uniform "liquid curtain." The substrate passes beneath this curtain to receive the coating. This method does not require contact with the substrate, making it suitable for high-speed production or irregular surfaces.

Core Advantages: High coating speed, no substrate damage.

Typical Applications: High-speed paper coating, surface coatings for irregularly shaped parts.

X. Spin Coating

Spin coating (also known as spin coating) utilizes centrifugal force generated by high-speed rotation to spread the coating evenly – as the substrate spins rapidly, excess coating is thrown off, resulting in an extremely thin and uniform film.

Core Advantages: Extremely high coating uniformity (nanometer level).

Typical Applications: Semiconductor photoresist coating, optical lens coatings.