Technology Alkyd Varnishes

Posted by Ralf on September 11th, 2016 — Posted in News

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Semi-finished alkyd varnish pentaphthalic are pentaphthalic solution resin (synthesized based on pentaerythritol and phthalic anhydride) in volatile organic solvents, and modified vegetable oils, synthetic fatty acids, fatty acids of vegetable or tall oil. To date, the domestic paint industry mainly produces only two brands semi-finished varnishes pentaphthalic – it's PF-060 varnish and lacquer PF-053, but the volume of production of coatings on the order volumes covers all the other semi-finished varnishes and resins in organic solvents. The fact that the varnish PF-060 and FS-053 is a major component of the most popular on the Russian market of alkyd paints, enamels and primers. It paints: PF-283 PF-231 parquet, PF-170; enamel: FS-115 FS-266 for the floor, the FS-1217 CE, PF-133 primer: GF-021 GF-0119 (in spite of preserved marked "GF" in primers, in recent years to make them basically use the PF-053 varnish). Synthesis of alkyd resins for paints semi-finished and PF-060 PF-053 is carried out in a reactor with a high-temperature heating (heating high-temperature coolants or elektroinduktsionny), also equipped with cooling and stirring. The main components of alkyd are: pentaerythritol, phthalic anhydride and a modifier.

Modifier are a variety of oils, mainly sunflower oil, dehydrated castor oil, soybean, cottonseed, etc. Recently, a large application received distilled tall oil fatty acids and tallow oil is a byproduct of pulp and paper industry. In the first stage of the process at temperatures up to 240 C, the process of interaction of pentaerythritol with vegetable oils, this stage transesterification or alcoholysis. In the second stage of the reaction mixture is introduced and phthalic anhydride at a temperature of from 180 to 210 C is getting ready oligomer (alkyd) – this stage polieterifikatsii. The reaction is controlled by modify the content of carboxyl groups in the reaction mass, which is estimated by acid number. Thus there is a mandatory drying alkyd, ie, removal from the reaction medium of water, which in large quantities formed under polieterefikatsii. Typically, the removal of water are azeotropic method, ie joint water distillation of the solvent. Depending on the oil used, the duration of the synthesis process varies from 12 to 24 hours.

Upon receipt of the finished alkyd, it is poured into a mixer equipped with a stirrer under a layer of pre-poured solvent. The solvents used mainly as xylene, toluene, solvent or their mixture with white spirit. The dissolution of alkyd oligomer in the first lacquer dry residue control and viscosity. The optimum viscosity for the finished semi-finished varnishes and PF-060 PF-053 – 60-90 seconds for vizkozimetru VZ-246 with nozzle diameter of 4 mm. Mass fraction of solids or dry residue should be within 52-55%. Then, the finished lacquer is subjected to a thorough cleaning on special filters and sent to the packing, storage, and consumers. An important parameter of ready PF-060 varnish and PF-053 is their color, which is usually determined by the hue of the initial components – namely vegetable oils. The higher the quality of the paint, the lighter it should be. Chroma paint PF-060 varies from 10 to 60 mg J2/100 cm3. Chroma paint PF-053 can be in the range from 100 to 300, and even up to 400 mg J2/100 cm3, but the best – not bolee130. Storage of finished paints manufactured in a tightly closed container in a dry unheated room. Shelf life – no more than 6 months. They must be protected from heat, moisture and direct sunlight.

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