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    Home > Coatings News > Paints and Coatings Market > The role and difference between medium primer, intermediate paint and finish with steel structure anticorrosive coating

    The role and difference between medium primer, intermediate paint and finish with steel structure anticorrosive coating

    • Last Update: 2021-01-02
    • Source: Internet
    • Author: User
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    If you want steel structure anti-corrosion to do well, good anti-corrosion support is no less. A lot of layman feel that steel structure corrosion protection is not just to take some paint brush on it?
    In fact, not, first of all, steel structure corrosion protection needs to be determined according to the use of the environment anti-corrosion paint matching, anti-corrosion paint varieties, such as indoor general corrosion environment can not be equipped with weather-resistant too good paint, epoxy coatings can not be used for outdoor environmental surface, anti-corrosion service life of long non-alcohol paint, the requirements of good corrosion performance to pay attention to anti-corrosion matching use. So, let's take a look at the steel structure anti-corrosion coating matching medium primer, intermediate paint and paint role and differences.
    (see all picture news from China Paint Online)The primer
    the first layer of coating matching, directly in contact with the substrate, its requirements and function are as follows:
    1) good adhesion. Primer needs to have a better adhesion to the substrate, anti-corrosion jun personally think that in the whole anti-corrosion supporting each coating adhesion in the primer adhesion is the most important, in the failure of anti-corrosion coating primer shedding is also the most common, of course, to exclude the construction surface treatment factors.
    In practice, cost-effective primers are generally epoxy primers, epoxy resin structure contains a large number of polar hydroxyl and ether bonds, they and adjacent interface materials can produce a strong adsorption force, so that epoxy paint for metal steel, cement, fiberglass, galvanized steel (modified epoxy paint), concrete, wood and other materials have excellent adhesion.
    2) anti-corrosion performance. Mainly from three aspects reflect the
    (1) shielding effect
    the metal surface coated with lacquer film after the metal surface and the environment separated, to prevent water, oxygen, ions through the coating to reach the steel surface, play a shielding role. Prevents corrosion when metals come into contact with corrosive substances such as water and air. This feature has this function as long as it is a coating.
    (2) pigment passivation, corrosion-reprieve
    pigment is an important part of the coating, rust-proof pigment and metal surface action, so that it blunts or produces protective substances to enhance the protective effect of the coating. In rust-proof primers often use large active anti-rust pigments, such as chromate and red dan, they have a certain passivation effect on the metal, in addition to chromate system as an example, when trace amounts of water through the paint film, a small amount of dissolved pigment will passivate the substrate. Therefore, the corrosion-reprieve effect can make up for the lack of shielding. In turn, the shielding effect can prevent the loss of corrosion ions, so that the corrosion inhibition effect is stable and long-lasting.
    these coatings are: iron epoxy red primer (iron red), red Dan primer, zinc epoxy yellow primer (zinc yellow), zinc epoxy phosphate primer, general epoxy primer and so on.
    (3) Cathode protection
    If there is a more active metal (lower electrode potence) powder than steel in the coating, such as zinc powder or aluminum powder, they can form a sacrificing anode cathode protection of steel, steel can be protected from corrosion, similar to galvanizing, life's common galvanized steel is rarely rusted? However, zinc-rich coating zinc content is too low to achieve cathode protection, very simple zinc powder can not come into contact with steel.
    -rich coatings are typical of these functional coatings. Such as: epoxy zinc-rich primer, inorganic zinc-rich primer, water-rich zinc-rich primer, in recent years more popular zinc primer and so on.
    (see all picture news from China Paint Online)Intermediate paint
    middle paint mainly act as a barrier, increasing the corrosion medium (water vapor, oxygen, chemical corrosive substances, etc.) to reach the substrate difficulty, because the paint coating as an anti-corrosion coating, is not completely closed, after amplification several times can be found that the coating surface has numerous small micro-holes, intermediate paint Painted on top of the primer, isolated substrate and water vapor and air contact, play a role in protecting the substrate from oxidation reaction, while extending the aging time of the primer, extend the primer life, increase the thickness of the middle paint can enhance the anti-corrosion effect and reduce costs (the middle paint price is lower than the primer and finish).
    addition, the middle layer also plays a role in increasing adhesion and filling. The overall thickness of the coating is mainly provided by primers and intermediate paints.
    typical intermediate paint is cloud iron intermediate paint, epoxy cloud iron intermediate paint, alcoholic acid cloud iron intermediate paint, etc. , through the mica iron oxide special fish scale physical arrangement nature isolated air and water vapor.face paint
    Generally speaking, the paint plays a decorative and protective role, it is the coating system's last coating, in order to make the decorative effect more beautiful and good-looking.
    (View all pictures of China Paint Online News)
    protection refers to: paint anti-pollution, anti-aging, chemical resistance, UV resistance and moisture resistance and other properties, so the general paint detection is salt-resistant fog, anti-artificial aging, moisture-resistant heat and other items. These functions are the reason to protect the entire corrosion protection system from failure, because primers and mid-paints, although they also have these functions, but very limited, once there is no surface paint protection intermediate paint and primer in the corrosive environment will soon fail. If the outdoor sun direct shooting environment if there is no paint, epoxy intermediate paint change color a week, up to a month will occur powdering, so these functions are very important indicators for paint.
    (see all image news from China Paint Online)
    JTT695-2007 Concrete bridge structure surface coating corrosion protection technical conditions require
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