Research and Application of Organic Fluorine Coatings (1)

【Abstract】With the continuous research, development and improvement of new materials, the research of organofluorine coatings will be more and more in-depth, and the performance will become more and more excellent to meet the different requirements of coatings in different industries or fields. At the same time, as people's awareness of environmental protection increases, organic fluorine coatings will also develop in the direction of pollution-free and environment-friendly. Organic fluorine coating as the best performance coating species, will increasingly attract people's attention, and get a wide range of deep-level applications in specific areas.

[Keywords] organic fluorine coating research

Organic fluorine materials are widely used because they have many excellent properties, occupy a very important position in the paint industry, and enjoy the reputation of "paint king". The organic fluorine coating is an organic fluorine polymer or organic fluorine modified polymer as the main film-forming material coating, has excellent weatherability, durability, chemical resistance and corrosion resistance, abrasion resistance, insulation, stain resistance Stain and stain resistance properties are widely used in construction, aerospace, electronics, electrical, mechanical and household daily necessities, wood furniture and other fields. It is a high-quality, new and unique coating with excellent performance. The film forming material of the organic fluorine coating of Wuhu is mainly the organic fluorine resin and organic fluorine modified resin (or modified organic fluorine resin).

1.1 Organic fluororesin

Conventional organic fluorine resins used in coatings are generally prepared by homopolymerization or copolymerization of monomers containing fluorinated olefins such as tetrafluoroethylene (TFE), vinyl fluoride (VF), and vinylidene fluoride (VDF). Excellent, widely used. Polytetrafluoroethylene (PTFE) coating is the best non-stick coating, non-wettability, low friction, and heat resistance in fluororesin coatings. It is mainly used in home products, food, rubber and plastic, automotive, precision machinery and other industries. Field, as an important anti-stick coating, heat-resistant coating, insulating coating and wear-resistant coating. Polyvinylidene difluoride (PVDF) coatings are generally obtained by emulsion polymerization, have excellent chemical resistance, excellent thermal stability and excellent weatherability, durability, wear resistance, widely used in architectural aluminum For metal coils, it can be used as a decorative and protective finish. The polyvinyl fluoride-ethylene copolymer (PFEVE) resin developed by Japan's Asahi Glass Co., Ltd. in 1982 solved the problem that the fluororesin was difficult to dissolve in conventional solvents, achieved room temperature curing, and greatly broadened the application of fluorine coatings.

Although organic fluororesins have many excellent properties, there are also some problems: generally require high-temperature curing, long curing time, inconvenient for large-area construction, poor adhesion to substrates, poor wetting of pigments, in organic solvents The solubility is also not good, the price is more expensive and so on. Therefore, organic fluorine resins and modified organic fluorine resins are commonly used together with other organic resins.

1.2 Organic Fluorine-Modified Resin

Organic fluorine-modified resins can generally have the advantages of two resins, making up for certain deficiencies in the performance of the two resins, thereby improving performance and expanding applications. The modification methods include physical blending and chemical reaction modification. Chemically modified products generally have better performance than physical blending modification. Chemical modification mainly involves the copolymerization of monomers with functional groups such as enols, enesters, olefinic acids, or other functional groups to form cross-linked copolymers, thereby allowing organic fluorine to obtain new properties. In organofluorine-modified other organic coating industries, fluorine-modified organic resins mainly include acrylic resins, polyurethane resins, epoxy resins, polyphenylene sulfide, and silicone resins.

1.2.1 Fluorinated Acrylic Coatings

The fluorine-containing acrylic coating not only retains the characteristics of good alkali resistance, color retention and gloss retention, fullness of the coating film of the acrylic ester coating, but also has the characteristics of organic fluorine resin weather resistance, stain resistance, corrosion resistance and self-cleaning performance, and is an integrated Excellent paint performance.

By introducing a fluorine-containing group to change the structure of the acrylate polymer, the performance of the acrylic resin is greatly improved, making it more widely used. There are mainly two methods for introducing fluorine-containing groups: one is to use a fluorinated acrylate monomer to copolymerize with an acrylate, and the other is to add a fluorine-containing additive such as perfluorooctanoic acid, a fluorocarbon surfactant and the like during polymerization. The former method can not only change the structure of the polymer side chains, effectively change the surface properties of the copolymers, but also does not significantly increase the cost, and has practical significance. The synthesis of fluorinated acrylate monomers mainly includes fluorinated alcohols and Methyl) acrylate; two preparation methods using perfluoroalkyl iodide and (meth) acrylate reaction. 3M, Du Pont, Asahi Glass, and Otsuka Organic Chemicals are all produced. The copolymerization of fluorinated acrylates can be initiated with gamma rays, peroxides, or azobisisobutyronitrile, and can be bulk, solution, or emulsion polymerization. After the film is formed, the fluorine-containing side chains can be concentrated on the coating film. The surface maximizes the effect of fluorine atoms and has excellent water resistance and stain resistance. At present, fluorine-containing acrylates have been successfully applied to optical fiber coatings, automotive coatings, architectural coatings and fabric treatment agents.

Tang Liming and others from Tsinghua University used polyvinylidene fluoride and polyacrylate as raw materials to synthesize polyacrylate modified emulsions with excellent performance through emulsion polymerization. The emulsion has good adhesion to the substrate and the surface properties of the coating film after the film formation are good, and can be used for the surface modification of the substrate in areas such as pollution resistance, heat resistance, chemical resistance, and non-stickiness, for example, for textiles. , leather products, water, oil and other fields.

(to be continued)