Water-based plastic paint oil repellent: a key additive to improve coating quality

In modern industrial production, water-based plastic paint is widely used in the surface coating of plastic products due to its environmental protection and safety characteristics. However, in actual use, water-based plastic paint often faces some challenges, such as paint film shrinkage, oil spots, Bernal vortices and other problems, which seriously affect the coating effect and product quality. The generation of these problems is largely related to factors such as oil stains on the surface of the substrate and mold release agent residues. In order to solve these problems, water-based oil repellent came into being, and it has become a key additive to improve the coating quality of water-based plastic paint.

1. The working principle of water-based oil repellent

Water-based oil repellent mainly reduces the surface tension of the coating film, improves the wettability of the coating to the substrate, and promotes the flow of the coating film, thereby preventing the occurrence of defects such as paint film shrinkage. Its working principle is mainly based on the following aspects:

Reducing surface tension: Water-based oil repellent has extremely high surface activity, which can significantly reduce the surface tension of water-based plastic paint, so that the coating can better spread and adhere to the surface of the substrate. For example, non-silicon modified polymer oil repellents can effectively reduce static and dynamic surface tensions and effectively eliminate paint film problems caused by substrate contamination with grease or release agents.

Improve wettability: Oil repellents can improve the wetting ability of coatings on substrates, especially for substrates contaminated with grease or with release agent residues, which can make the coating cover and adhere better and avoid the occurrence of oil spots and oil spots. For example, some non-ionic surfactant oil repellents can play a dual role of oil repellency and improving wetting in water-based industrial coatings, water-based wood coatings and other systems.

Prevent shrinkage and fish eyes: By changing the surface tension distribution of the coating, oil repellents can prevent uneven surface tension caused by pollutants, thereby avoiding the formation of defects such as shrinkage or fish eyes. In complex color coating products, it can also prevent the color separation of the product and improve the uniformity and aesthetics of the coating.

2. Types and characteristics of water-based oil repellents

There are mainly the following types of water-based oil repellents on the market, each of which has unique characteristics and scope of application:

Non-silicon modified polymer type: modified with non-silicon polymers as the main component. It has good oil resistance and can effectively prevent the penetration and adhesion of oil substances in water-based systems. It is widely used in water-based inks, coatings, adhesives and other fields, and can solve the paint film problem caused by oil stains on the substrate 

without affecting the recoatability. At the same time, it has excellent compatibility and miscibility, which can significantly improve the wettability, permeability, fluidity and leveling of the coating system. However, hydrolysis may occur under acidic and alkaline conditions, and it is necessary to pay attention to adjusting the pH value of the system when using it.

Non-ionic surfactant type: It belongs to non-ionic surfactants and has certain defoaming and wetting effects. In water-based industrial coatings, water-based wood paints, fountain solutions, water-based plastic paints, water-based inks and other systems, it can play an oil-resistant and wetting-improving role, improve the oil-resistant ability of water-based coatings and adhesives, reduce the cleanliness requirements of the substrate, and has good solubility in water-based systems, which can help the coating have good spreadability in oil-bearing coatings and silicone adhesive joints.

Fluorine-modified polysiloxane type: such as water-based oil-repellent agent DZ-6611, has excellent performance in reducing surface tension, can provide rapid spreading and wettability, enhance the flow and leveling of paint films, eliminate surface defects such as orange peel and shrinkage holes, and can be applied to water-based systems to effectively solve the shrinkage hole problem of paint films.

3. Advantages of water-based oil-repellent agents in water-based plastic paints

Solve paint film defects: effectively eliminate paint film shrinkage holes, oil spots, Bernal vortices and other defects caused by oil stains on the substrate, mold release agent residues, etc., improve the flatness and finish of the coating film, and make the product appearance more beautiful.

Improve production efficiency: reduce rework and scrap rate caused by paint film defects, improve production efficiency and reduce production costs.

Enhance coating performance: improve the adhesion of coating to substrate, improve the scratch resistance, wear resistance and weather resistance of coating, and extend the service life of the product.

Environmental protection and safety: Water-based oil repellents are usually environmentally friendly, non-toxic, and odorless, which meets the requirements of modern industry for environmental protection and safety, and reduces harm to operators and the environment.

4. How to use and precautions for water-based oil repellents

How to use: The amount of water-based oil repellent added is generally 0.1% - 2% of the total system amount. The specific amount of addition needs to be determined by testing according to the coating formula, substrate conditions and actual use requirements. It can be added at any stage of the product production process, but it is recommended to add it slowly during stirring to ensure that it is evenly dispersed in the coating system. For example, some oil repellents with high active ingredients are recommended to be diluted with dimethylbenzene to a 10% solution before use.

Note: Before use, the coating system and substrate must be fully evaluated to ensure that the oil repellent has good compatibility with the coating system. At the same time, pay attention to the pH value of the system. Some oil repellents may affect their performance under acidic or alkaline conditions. In addition, the oil repellent should be stored in a cool, dry, ventilated place, away from direct sunlight and high temperature environment, away from fire and oxidants.