Rubber coatings (code J) are coatings of different types and uses based on natural rubber derivatives or synthetic rubber as the main film-forming substance, mixed with various natural or synthetic resins, pigments, plasticizers, and solvents . The resins used include natural resins, rosin resins, phenolic resins, alkyd resins, acrylic resins, and the like. Natural rubber is a highly unsaturated polymer with high relative molecular weight, slow , and easy aging. It is not suitable for coatings. It must be chemically treated to reduce its relative molecular weight and change molecular unsaturation. into natural rubber derivatives, such as chlorinated rubber and cyclized rubber. Synthetic rubbers that can be used to make coatings include styrene-butadiene rubber, neoprene rubber, chlorinated neoprene rubber, chlorosulfonated polyethylene rubber and polysulfide rubber. There are mainly the following varieties.
(1) Chlorinated rubber coating
Chlorinated rubber is produced from natural rubber after mastication and depolymerization, or isoprene rubber dissolved in carbon tetrachloride and chlorinated. The chlorine content of industrial products is generally 60% to 67%. Chlorinated Rubber Via Natural Tree
Chlorinated rubber coatings are made by modifying grease or synthetic resins, pigments and additives. Chlorinated rubber paint is a volatile paint, which dries quickly and can be applied at a temperature of -20~50°C without seasonal restrictions. Generally single-can packaging, easy to use. It is easy to get thick coating with this paint, generally the dry film thickness of each layer can reach 55~85μm, and the maximum dry film thickness of one layer can reach 120μm. Chlorinated rubber coatings have good durability, weather resistance and anti-corrosion properties. They have extremely high water permeability, good resistance to acids, alkalis, salt water and salt spray, water resistance, oxidant resistance, and low water vapor permeability. The paint film has high chlorine content and has anti-mildew and flame-retardant effects; but it has poor heat resistance, decomposes at 130°C, and begins to decompose at 60°C in a humid environment, so the use temperature should not exceed 60°C, and its UV resistance is poor, and it is affected by ultraviolet rays. Exposure to light can easily cause damage such as cracking and aging of the paint film. Therefore, in the coating components , synthetic resins with excellent weather resistance should be considered for modification.
Chlorinated rubber coatings can be divided into steel structure paints and wall paints, which are mainly used for steel corrosion protection in harsh environments, chemical product equipment, port underwater and ship paints, chemical-resistant paints and cement building topcoats ; It can be used as fireproof paint, road marking paint and ship bottom antifouling paint; varnish can be used for waterproofing and moistureproofing of wood and paper packaging boxes.
In the production process of chlorine rubber, the rubber is dissolved in carbon tetrachloride to pass through chlorine. There is more carbon tetrachloride in the finished product, which pollutes the atmosphere and is restricted by various countries. As a result, some production plants have stopped production, reduced production or improved processes.
(2) Neoprene coating
The film formation of neoprene coatings mainly depends on "vulcanization" cross-linking. The commonly used vulcanizing agents are metal oxides (such as zinc oxide and magnesium oxide), and reinforcing agents, accelerators, anti-aging agents, etc. need to be added. A cross-linking agent can also be added to form a room temperature curing coating, and natural or synthetic resins are often added to improve its film-forming properties. Neoprene coating has excellent chemical resistance, weather resistance, ozone resistance, heat resistance, oil resistance and alkali resistance . But its color tends to become darker, so it is not suitable to be made into white or light-colored paint. Neoprene anti-corrosion coatings can protect various objects in underground, underwater or corrosive media and humid environments; they can be coated on chemical production equipment, storage tanks, pipelines and ships. Neoprene peelable paint can be used as a protective layer during chemical milling of aluminum and steel plates.
(3) Chlorosulfonated polyethylene rubber coating
Chlorosulfonated polyethylene rubber coating (Hiberon) is a cross-linkable elastomer made of polyethylene dissolved in carbon tetrachloride and reacted with chlorine and sulfur dioxide under the action of azobisisobutyronitrile. There are chlorine atoms in the main chain of polyethylene, which can enhance the oil resistance, flame resistance, solvent resistance of the coating film and improve its physical and mechanical properties. This fully saturated rubber without double bond structure has excellent weather resistance , aging resistance, ozone resistance, chemical resistance and oxidation resistance. It can be used at a temperature of 120°C or higher , and it will not become brittle at -50 °C without adding plasticizers . It has low water absorption and excellent flex life. Are chlorosulfonated polyethylene rubber coatings suitable for surface protection of radome in telecommunications ? Chemical corrosion-resistant coatings for steel frames, bridges, and cement walls of outdoor and chemical equipment, waterproof facilities such as reservoirs, Water Tanks, and sewage pools, oil mining, oil refining system buildings, equipment, oil pipeline oil-resistant coatings, and rubber product coatings. Chlorosulfonated polyethylene coatings are generally packaged in two-component packages. The surface is dry after the solvent evaporates , but it takes a few days for complete cross-linking and curing.
(4) Styrene-butadiene rubber coating
Styrene-butadiene rubber (SBS) is a block copolymer of styrene-butadiene-styrene, which also has the characteristics of rubber and plastic. Adjusting the ratio of butadiene and styrene can control the hardness of the product. This kind of coating is fast drying, water-resistant, chemical-resistant, and wear-resistant. It can be used as cement floor paint, corrosion-resistant paint, temporary protective paint for aluminum alloy chemical milling, etc.
