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Research progress of rubber products, surface coatings with fluoride

Rubber products by virtue of their unique excellent characteristics with modern synthetic rubber technology and processing industries are maturing, more and more applications to the automotive, electronics, aerospace and other high-tech fields. Meanwhile, the performance plastisol coated chain requirements of the rubber products more and more stringent, but the rubber material itself in the harsh environment of high temperature, high radiation, high pollution, anti-aging, corrosion resistance, weather resistance, abrasion resistance deficiencies, and affect their life and range of applications. The properties of the rubber products depends largely on the performance of its surface layer, so the surface of the rubber products for coating modified, can be effective in prolonging the period of use of the rubber products.
    The fluorine-containing coating is a fluorine-containing polymer or an organic fluorine-modified polymer is the main film coating material having excellent thermal stability, high chemical inertness, weather resistance, pollution resistance and non-adhesion and other properties. Fluorine-containing coating on the surface of the rubber products, the painting modified, can effectively improve the surface properties of the rubber products.
    The performance characteristics of the 1 · fluoropolymer coatings
    Usually the carbon chain of the polyolefin molecule is serrated, in the fluorine-containing coating, due to the electronegative fluorine atom large (4.0), a small atomic radius (0.13nm), CF bond length, bond energies, adjacent fluorine atom mutually exclusive, so that CCC bond angle in the main chain by 112O becomes 107o, a fluorine atom is not in the same plane, for spiral distribution along the carbon chain, and the carbon chains surrounded by fluorine atoms tightly wrapped up, play a good shielding effect. Symmetric distribution such that the entire molecule to a non-polar covalent bond can reach 544kJ/mol; perfluoro compounds, can well withstand the ultraviolet part of the sunlight in the destruction of organic matter, so the fluorine-based coating having excellent weatherability. The chemical resistance of the fluorine-based coating is also very good, because the more fluorine atoms than hydrogen atoms, the CC bond enclosed, so that any atom or group can not enter and damage the CC bond.
    2 the classification of the fluorine-containing coating
    2.1 vinyl fluorine-containing coating bell Hin et al [1] Preparation of a polytetrafluoroethylene as a main component a water-soluble fluorine-containing coating, spraying the surface-modified hydrogenated nitrile rubber (HNBR) of specimen studied its friction properties, and with expandable graphite modified HNBR specimen surface for comparison. The research results show that the fluorine-containing coating to spray modified HNBR specimen surface friction early you can get a very low friction coefficient, and a long time to maintain; expanded graphite modified HNBR sample early start a high coefficient of friction.
    Of 2.2 epoxy-based fluoropolymer coatings
    Epoxy resin having excellent adhesive properties, and can compensate for the deficiencies of the fluorine resin adhesive force difference in maintaining the fluorine resin excellent in corrosion resistance, low surface energy at the same time improve the resin adhesive force, so that the coating significantly improved performance.
    Cheng-Zhong Wang, left, Yu et al. [2] the synthesis of isocyanate terminated fluorine-containing compounds grafted to a bisphenol A epoxy, to form a side chain a fluorine-containing epoxy resin, the purpose is to keep the epoxy resin excellent in adhesion force at the same time improve their surface properties, set in one of the advantages of the epoxy resin and a fluorocarbon resin, to obtain a new kind of a resin material, the test results show that the toughness and electrical properties of the fluorine-containing epoxy resin has been significantly improved.
2.3 fluorinated acrylic polymer coating
    The acrylic esters material having excellent adhesion properties. Although FC bond than the CH bond in the acrylic acid is a good chemical resistance, but lacks some of the advantages of acrylic acid, therefore the organic fluorine group is introduced in the acrylic polymer prepared fluorinated acrylate coating, not only retains good alkali resistance acrylate paint gloss coating fullness and color retention, and organic fluorine resin weathering stain resistant, corrosion-resistant and self-cleaning properties of the advantages of a comprehensive performance paint.
    Tsinghua Tang L., et al. [3] to the polyvinylidene fluoride and polyacrylates as the raw materials, synthetic performance polyacrylates modified emulsion by emulsion polymerization method. Good adhesion of the emulsion and the substrate, the properties of the surface of the film after film formation, and can require pollution, heat resistance, chemical resistance and nontacky areas for the surface modification of a substrate, such as for the field of textiles, leather products, water, oil, etc..
    2.4 fluorinated silicide coatings
    Fluorinated silicone coating can be cured at room temperature film formation, has excellent corrosion resistance, impact resistance, adhesion and weather resistance, service life of up to 20 years. WB99 fluorine-containing silicone Technology Co., Ltd. and Shanghai Fu developed silicone coatings have been successfully applied in the Coating Protection Nanpu Bridge cable polyethylene casing [4]. Mera developed fluorinated silicone antifouling coatings, apply to the the Hoi Ha tanks, ships, fishing nets, docks protection [5]. Such as Du Huiru, Chen Fang [6] a good waterproof and anti-permeability silicone fluoride materials, penetration depth, contact angle, permeability, resistance to freezing and thawing, salt crystals, acid, and alkali, etc. series of experiments to assess the effect of the application of the material in the sandstone heritage preservation. Results: silicone fluoropolymer sandstone heritage well protected material.
    2.5 fluorinated polyurethane coatings
    Fluorinated polyurethane coatings with excellent weather resistance, corrosion resistance, color retention and heat, can be cured at room temperature, chemical resistance, and its overall performance is unmatched by other paint, it is widely used in the aerospace, marine anti-corrosion, bridge vehicles and construction, aluminum, cement, steel, plastic, rubber, wood surfaces, good protective and decorative coatings. As the functional group of the fluorine-containing copolymer and the polyisocyanate room temperature crosslinking, not only having a fluorine resin excellent in chemical properties, are widely applied and has a universal paint performance.
    Francis Cheung et al [7] Synthesis of a hydroxyl group-containing fluorine and silicone resin, and 60 parts of this resin raw material, methyl isobutyl ketone / xylene (2:1) 30 parts 10 parts, additives, HDI25 parts as curing The agent made of varnish. The varnish will not only maintain the good adhesion and mechanical strength, but also has high heat resistance, weather resistance, good water repellency and stain resistance, and expected to have great potential value in the anti-corrosion coatings and antifouling paint.
    3 fluorine-containing coating in the surface of the rubber products in the
    Along the coating is difficult to attach to the rubber surface coatings developed in the first thing to consider. First, the metal surface is a high-energy surface, easy to attach, and the rubber surface tension <100mN/cm low energy surfaces, coating thereon is difficult to wetting and spreading. To the liquid on the solid surface wetting and spreading of the tension of the table must be less than the solid surface tension can be achieved, which will be the surface tension of the coating is limited within a certain range, while the coating surface tension is the surface tension of the binder resin and a solvent comprehensive reflection, you must select the appropriate coating system. Generally, the coating resin and the rubber substrate structure is similar, and good compatibility (solubility parameter similar), the polarity similar in order to make a good adhesion of the coating resin in the rubber surface; followed by the rubber products, is a special kind of substrate, its high elasticity (low modulus), good flexibility, easy deformation occurs, match the requirements of the coating is high, generally the relative elongation of as rubber coating technology indicators selection similar to the thermal expansion coefficient with the substrate, low modulus, flexibility good paint, and does not occur due to climate impact film off, crack, wrinkle phenomenon, harsh conditions and even paint rubber products to meet large deformation occurs often use.
Science Institute [8] building structure developed for the surface of the coating rubber of the coating is by a fluorine rubber, a fluorine resin, an amine curing agent, and other components. The coating solution is applied vulcanizates. Rubber pre-processed, and then the rubber sample is placed in the vulcanizing agent was immersed 1h (vulcanizing agent to infiltrate into the fluorine content of the fluorine rubber surface layer, and promote further co-vulcanization of the coating and the substrate) and then dried. The coating by incubator for 1 hour at 100 ℃ sulfide. In addition to the development of fluoropolymer coatings painted on the automotive rubber gasket, drawn by the in Yake Ji extreme climatic conditions, such modified gasket use than industrial production doubling or more. This shows that the work under complex conditions of this fluoropolymer coatings can be used in the far north of the rubber parts production. KSatoh et al [9] using the sol - gel method in printing fluoropolymer film coated with a layer of silicone rubber disk to improve the performance of silicone rubber, studies have shown can reduce its surface after surface modification of silicone rubber, at the same time it The Hardness, hate ink rubbings durability have been improved. NDTran et al [10] with a plasma polymerization the legitimate will PFMCH (perfluoro-methylcyclohexane) is applied to the surface of the EPDM (ethylene propylene diene monomer rubber), and under the conditions of moisture and ultraviolet presence of EPDM, weather resistance were research. The study results show that: fluorine atom elimination and the introduction of oxygen-containing functional groups play a vital role in degradation of the coating. PFMCH processing EPDM wear resistance than pure EPDM much better. The adhesion between the substrate and coating is also very good.
    4 · Conclusion
    Protection fluoropolymer coating surface coating of plastic, rubber and polymer products in China has just started, many ways is not very mature, can not be compared with the protection of metallic materials. But we can see that there is a huge application market in the field of protection with a fluoride coating the surface of the plastic, rubber and polymer products. The majority of researchers and coating workers need to fully understand the nature of plastic, rubber and polymer products, as well as the nature of the fluorine-containing coating, performance; understanding of the characteristics of coated products, uses and requirements; can be more effective, more economical manner painting, to better improve the surface of the protective effect of polymer products. With the rapid development of the technology of the fluorine-containing coating, fluorine coating polymer products such as plastics, rubber, surface protection field has a very broad application prospects.

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