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    Home > Coatings News > Paints and Coatings Market > Development of PVDF fluorocarbon powder coatings.

    Development of PVDF fluorocarbon powder coatings.

    • Last Update: 2020-10-28
    • Source: Internet
    • Author: User
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    Abstract: PVDF fluorocarbon powder has the advantages of high quality, environmental protection, high efficiency and energy saving, this paper introduces the modified thermooensocarbon resin and PVDF resin, the preparation of excellent performance of PVDF fluorocarbon powder coating development method;0 Introduction
    PVDF, full name polydifluoroethylene, is a thermoplastic polymer material with a particularly stable chemical structure, with excellent chemical corrosion resistance and UV aging resistance. Fluorocarbon coatings with PVDF as the main component show excellent weather and chemical resistance, but also have low surface pressure, low friction, hydrophobic and self-cleaning and other excellent performance, has been widely used in the construction industry, chemical industry and electrical and electronics industry . Outdoor life of up to 20 a data (1-2) is the field of specialty coatings up to the fore. PVDF fluorocarbon coating varieties and output increased year by year, the current application of China's PVDF fluorocarbon coatings mainly concentrated in the field of building materials, especially high-end building curtain walls, public venues and aluminum doors and windows. In addition, PVDF fluorocarbon coatings in petrochemicals, electronics, food industry, nuclear power industry, marine, marine engineering and other fields have broad application prospects. With the further expansion of China's infrastructure construction and the expansion of fluorocarbon coating applications, the future PVDF fluorocarbon coatings market has great potential for development.
    However, the current domestic PVDF fluorocarbon coating application form is still solvent-based, solvent-based PVDF fluorocarbon coating production and construction process has been relatively mature, good coating performance, high market recognition. However, due to solvent-based PVDF fluorocarbon coatings during construction, about 50% waste and about 70% of solvent volatilization, resulting in serious environmental hazards and waste. In recent years, the state's environmental protection requirements are getting higher and higher, and a series of environmental protection policies have been issued to limit high-polluting industries and products. In 2014, paint was first identified as a polluting industry by the relevant state administration departments. In 2015, the Ministry of Finance and the General Administration of Taxation issued the Notice on the Collection of Consumption Tax on the Battery and Coatings Industry (Treasury Tax No. 16), which imposes a consumption tax on coatings with volatile organic matter content higher than 420 g/L under construction. Therefore, the development of environmentally friendly coatings has become the focus of the domestic paint industry in the future.
    powder coating is an environmentally friendly coating. Since solvents are not used and there are no environmental problems caused by solvent volatilization during construction, powders can also be completely recycled, thus having a clear advantage over
    solvent-based coatings in terms of environmental friendliness and process economy. PVDF fluorocarbon powder coatings replace PVDF fluorocarbon liquid coatings in large numbers, which will play a very important role in complying with the national low-carbon environmental protection and high-performance green development of the coating industry, meeting the consumption demand of the coating market for zero VOC fluorocarbon coatings, promoting the structural adjustment of China's coating industry, and enhancing the overall competitiveness and level of the industry.
    the PVDF fluorocarbon powder coating has been used in small quantities due to its thick coating and poor adhesion. With the development of PVDF fluorocarbon powder coating technology, its performance has been greatly improved and its usage has increased rapidly. Traditional PVDF fluorocarbon coatings typically use 30% acrylic resin to moisturize inorge pigments and increase adhesion. PVDF fluorocarbon powder coatings require better coating adhesion, and traditional thermoplastic acrylics do not provide sufficient adhesion. Conventional acrylics are difficult to be compatible with PVDF resins, resulting in poor adhesion and adhesion. The current modified acrylic technology and the ultra-refinement of PVDF powder coatings are the focus of research. In this study, epoxy resin modified acrylic acid was obtained with PVDF compatible resin, solved the problem of compatible with PVDF powder coating, thereby improving the adhesion, hardness and impact resistance of the paint film;
    1 Experimental part
    1.1 epoxy resin modified acrylic resin
    to the 10 L four-mouth jacket reactor equipped with condensing device, agitator, constant pressure funnel, oil bath temperature heating device to add epoxy resin and mixed solvent, stirring, heating up to 110 degrees C. Under the protection of nitrogen, the co-clustered monomer dissolved with benzoyl peroxide is slowly added to the reaction system, dripped within 2 h, and then supplemented with a positive butanol solution containing the trigger. Heat up to 110 to 115 degrees C, keep warm about 4 h, to make a joint polymer epoxy-acrylic resin. Cool the resin solution to 90 degrees C, add diethanolamine (added within 0.5 h), heat up to 100 degrees C, react 2 h; cool down to 80 degrees C, add acetic acid neutral, react 0.5 h to pH , 5.8 to 6.6, add deionized water dilution, make epoxy modified acrylic.
    quality scores of epoxy resins are 0, 0.5%, 1%, 1%, 1.5%, and 2% of acrylic quality, respectively, and the coating numbers are HA 0, HA 1, HA 2, HA 3, HA 4.
    1.2 PVDF fluorocarbon powder coating and the use of three-stage crushing technology to
    . The preparation and three-stage crushing technology of the PVDF fluorocarbon powder coating is shown in Figure 1.
    Reduces the particle size of the PVDF fluorocarbon powder coating by using appropriate processing aids and extruder screws, and uses airflow crushing in the "Airflow Crush/Drying" procedure to dry the particles while also airflowing, ensuring that the crushed powder coating particles do not clagulate due to condensate. The PVDF powder particle size prepared through this process is around 30 m.
    1.3 PVDF fluorocarbon powder coating particle size determination
    stirs the PVDF fluorocarbon powder coating well in water containing surfactants and disperses the ultrasonic sound, then adds it to the sample pool and loads it into the sample rack of Malvern Instruments' ZetaTizer Nano-ZS laser particler until the temperature stabilizes (about 5 min). The instrument light source is the He-Ne laser, the dispersion medium is water, the temperature is measured at 25 degrees C.
    1.4 Paint film conventional performance test
    (1) with paint film thickness meter to measure the thickness of the paint film, select the paint film thickness (35±5) sm aluminum plate to be tested conventional mechanical performance.
    (2) adhesion, paint film hardness, shock resistance, gloss according to GB/T 9286 - 1998, GB/T 6739 - 2006, GB / T 1732 - 1993, GB / T 9754 - 1988.
    2 Results and Test results on the particle size and particle size distribution of
    2.1 PVDF fluorocarbon coatings
    the size and distribution of PVDF fluorocarbon powder coating sizes through nanoparticle analysis instruments. Figure 2 shows the particle size distribution curve of the PVDF fluorocarbon powder coating. As can be seen from Figure 2, the particle size distribution range of PVDF fluorocarbon powder coatings is narrow and uniform, with a particle size range of approximately 30 m.
    2.2 Paint film routine performance test results
    When acrylic resin and PVDF resin have good compatibility, in the PVDF fluorocarbon powder coating after the heating and curing process, PVDF particles will soften and melt with acrylic resin to form a dense "polymer alloy" to ensure the integrity of the coating, gloss, transparency and flexibility. In addition, the properties of acrylic resins themselves have an effect on coating properties. The compatible between the existing modified acrylic and PVDF resins is not ideal, and there are problems with insufficient hardness and adhesion. Therefore, consider introducing epoxy structure into acrylic resin, and functionalizing the acrylic resin by copolymerizing different acrylic monomers with epoxy resin, so as to further improve the coating structure, improve coating adhesion, paint film hardness, shock resistance, and improve the performance of PVDF fluorocarbon powder coating.
    2.2.1 Effect of epoxy resin modified acrylic resin on PVDF fluorocarbon powder coating film adhesion
    Paint film adhesion refers to the ability of the paint film to bind to or coating between the coating surface. Adhesion is an important technical index and a prerequisite for a series of properties of lacquer film. The paint film with good adhesion is durable and has the performance required for use, and the paint film with poor adhesion is easy to crack, fall off and cannot be used. Table 1 shows the effect of different mass fractions of acrylic quality on paint film adhesion of epoxy resins on aluminum plates.
    from Table 1, as the content of epoxy resin in acrylic resin increased, paint film adhesion first increased and then decreased. With the addition of epoxy resin in acrylic resin to improve its compatible with PVDF resin, increased the density of the paint film, while increasing its binding force to the substrate.
    2.2.2 Effect of epoxy resin modified acrylic resin on the hardness of PVDF fluorocarbon powder coating
    The hardness of the lacquer film is the resistance of the paint film surface to the object on which it is applied and another object with a higher hardness, reflecting the anti-scratching, wear-resistant and pressure-resistant performance of the coating. The test instruments used for film hardness include swing rod damping hardness meter, scratch hardness meter, indentation hardness meter, pencil hardness meter, etc. Table 2 is the pencil hardness value of the corresponding paint film.
    can be found in Table 2, with the amount of epoxy resin in acrylic resin increased, the hardness of the paint film did not change.
    2.2.3 Effect of epoxy-modified acrylic resin on the impact resistance of PVDF fluorocarbon powder coating film
    Usually the strength of the material is high, the deformation is large, and the impact resistance is high.
    As can be seen from Table 3, with the increase of epoxy resin content in acrylic resin, the impact resistance of the paint film gradually increased, and has a higher value, which is mainly the introduction of epoxy resin to improve the toughness of the paint film.
    2.2.4 Effect of epoxy resin modified acrylic resin on the luster of PVDF fluorocarbon powder coating
    the luster of paint film is an important indicator for decorative coatings. Gloss is difficult to have an exact definition, is generally considered to be the paint film surface projection of the light on the mirror reflected out of the ability, the more the amount of reflected light is
    large, then the higher the gloss, which is called specular gloss.
    As can be seen from Table 4, with the increase of epoxy resin in acrylic resin, the gloss of the paint film is gradually reduced, and when the content of epoxy resin and acrylic resin is 2%, the gloss decrease is more. Therefore, when the content of epoxy resin and acrylic resin does not exceed 1.5%, the gloss has an ideal value.
    3 Conclusion
    functionally modifies acrylic resin by copolymerizing different acrylic monomers with epoxy resins, which can improve coating adhesion, paint film hardness, resistance, and resistance when the amount of epoxy resin is 1% to 1.5% of acrylic resin content. Impact and other PVDF fluorocarbon powder coating performance, and ensure that the gloss of the coating within a reasonable range, the use of three-stage crushing technology to reduce its particle size to about 30 m, in order to ensure the performance of the coating at the same time significantly reduce the thickness of the coating, coating thickness from 60 to 100 m to 30 to 50 m.
    .
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