- Alkyd Resin Production Process Filetype Pdf Editor Online
- Alkyd Resin Production Process Filetype Pdf Editor Software
The second stage which takes place in the same reactor is the actual formation of the alkyd proper. The monoester formed in the first stage is cooled slightly to about 210oC and the requisite quantity of phthalic anhydride is added.
The resin is then partially cooled with water coils, and at the same time a thinning solvent is added. The partially diluted alkyd solution is run into a blender, passing through a filter press to remove any gel particles that are formed. The completed alkyd solution is then pumped to a second filter press for clarification and then to storage tanks or immediate use.Synthesis from Oils or Fatty Acids.Monoglyceride Process.
Alkyd Resin Production Process Filetype Pdf Editor Online
In the case of glycerol alkyds, it would be absurd to first saponify an oil to obtain fatty acids and glycerol, and then reesterify the same groups in a different combination. Rather, the oil is first reacted with sufficient glycerol to give the total desired glycerol content, including the glycerol in the oil. Since PA is not soluble in the oil, but is soluble in the glycerol, transesterification of oil with glycerol must be carried out as a separate step before the PA is added; otherwise, glyceryl phthalate gel particles would form early in the process.
This two-stage procedure is often called the monoglyceride process.The transesterification reaction is run at 230–250◦C in the presence of a catalyst; many catalysts have been used. Before the strict regulation of lead in coatings, litharge (PbO)was widely used; the residual transesterification catalyst also acted as a drier. Examples of catalysts now used in the United States are tetraisopropyl titanate, lithium hydroxide, and lithium ricinoleate. The reaction is run under an inert atmosphere such as CO2 or N2 to minimize discoloration and dimerization of drying oils. Rather than using glycerol, the transesterification can also be carried out with higher functionality polyols such as pentaerythritol.Fatty Acid Process. It is often desirable to base an alkyd on a polyol (eg, pentaerythritol) other than glycerol.
In this case, fatty acids must be used instead of oils, and the process can be performed in a single step with reduced time in the reactor. Any drying, semidrying, or nondrying oil can be saponified to yield fatty acids, but the cost of separating fatty acids from the reaction mixture increases the cost of the alkyd. A more economical alternative is to use TOFA, which have the advantage that they are produced as fatty acids. Tall oil fatty acid composition is fairly similar to that of soybean fatty acids.
Specially refined tall oils with higher linoleic acid content are available, as are other grades that have been treated with alkaline catalysts to isomerize the double bonds partially to conjugated structures. Generally, when fatty acids are used, the polyol, fatty acids, and dibasic acid are all added at the start of the reaction, and the esterification of both aliphatic and aromatic acids is carried out simultaneously in the range of 220–255◦C.“Alkyd Resins” in EPST 1st ed., Vol. 663–734, by R.
Alkyd Resin Production Process Filetype Pdf Editor Software
Silver, HerculesPowder Co.; “Alkyd Resins” in EPSE 2nd ed., Vol. 644–679, by H.
Lanson, Lan ChemCorp.Related posts.