Types of water-based fluorocarbon emulsions

According to the structure and film-forming mechanism of water-based fluoropolymers, thermoplastic and thermosetting fluoropolymer coatings can be produced. At present, the vast majority of water-based fluoropolymers or coatings produced and sold on the market are thermoplastic. For example, the fluoropolymer emulsions sold in my country by Asahi Glass, DIC Corporation, Daikin Corporation, etc. are all thermoplastic. Generally speaking, the cross-linking and curing reaction of the polymer occurs during the film formation of thermosetting fluoropolymer coatings, so the coating has better mechanical properties, weather resistance and chemical resistance. To give full play to the properties of fluoropolymer coatings, To improve film performance, it is necessary to formulate the waterborne fluoropolymer coating into a thermoset form. Among thermosetting water-based fluoropolymer coatings, they can be divided into two types: single-component and two-component according to the packaging form of the coating. In addition, branched-chain fluorine-containing modified emulsions also have the properties of fluorine emulsions in some properties. Because their synthesis is relatively simple, they are also widely used.

①Fluorine-modified acrylic emulsion

Water-based acrylic emulsion itself has good weather resistance and stability, but its water resistance and high temperature resistance are relatively poor. Now through the acrylic branch chain The technology of fluorine modification of the structure can change some of the poor properties of acrylic acid itself, and the synthesis method is relatively simple, so it is widely used in practical applications. However, since the emulsion obtained by this method only contains branched fluorine, the fluorine content is generally relatively low! It is about 10, and although it performs better than ordinary acrylic during use, it does not meet the high requirements of fluorocarbon coatings. Therefore, the coating made from this kind of emulsion cannot be completely called fluorocarbon coating.

②Two-component room-temperature curing fluorine emulsion

Asahi Glass Co., Ltd. has developed two-component room-temperature curing water-dispersed fluororesin coatings such as FE-4200 and 4400. Polyoxyethylene ether macromonomer (EOVE) with internal emulsification is introduced into the FEVE structure to prepare FEVE resin for emulsion-type two-component coatings, which is also an alternation of chlorotrifluoroethylene (CTFE) and vinyl ether. Structure of polymer. Hydrophilic modified polyisocyanates are commonly used as curing agents, which can achieve similar properties to solvent-based FEVE resins. In addition to being used on the surfaces of inorganic building materials such as concrete and cement boards (such as exterior wall coatings), it can also be used on metal substrates with excellent performance.

③Thermoplastic one-component fluoropolymer emulsion

Daikin Company has developed the ZEFFLE SE series of fluoropolymer aqueous dispersions, which are vinylidene fluoride (VDF) polymers.

Mixture with polymethylmethacrylate (PMMA) at the molecular level. Due to the strong interaction between the ester group of PMMA and the PVDF unit

the ester group can be protected by PVDF, so the coating film has good water resistance and excellent weather resistance .

④Room temperature cross-linking fluorine emulsion

Asahi Glass Co., Ltd. used seed emulsion polymerization technology to synthesize single-component room temperature cross-linkable PFEVE, carbonyl-containing diacetone acrylamide and other acrylic monomers. Body polymer, this type of resin is referred to as FEVE-AC. Thermal polymerization of FEVE and acrylic polymer produces a polymer with a core-shell structure, which can form a homogeneous, transparent coating, while the physically mixed FEVE and acrylic emulsion form a separate opaque coating. In the FEVE-AC coating, even if the acrylic monomer content accounts for 15% of the total, the gloss retention remains 80% after passing the SWM aging test for 4000h.

⑤Water-based fluoroelastomer emulsion

Fluororesin emulsion generally has higher hardness and less than ideal elasticity. Fluoroelastomer-based coatings are mainly used for coating metal, fabric, cement, Plastic and rubber. However, solvent-based fluoroelastomer coatings use ketones as solvents, and the solid content is 20-40. The curing agents are generally amines and aminosilane. The service life (activation period) is short, only 2-4 hours, and the coating must be double-packed. The newly developed water-based fluoroelastomer polymer introduces functional groups that may undergo cross-linking reactions within or between molecules. It uses partially hydrolyzed aminosilane as the curing agent and optimizes its dosage. A single package can be stored stably for 4 months.

Water-based fluoroelastomer coatings reduce a large amount of VOCs and can replace solvent-based coatings in automotive, chemical, aerospace and other industrial applications.

Compared with the wider application fields and convenient construction methods, the current hot spot in water-based coating research is still single-component room temperature cross-linked fluorine emulsion.