alkyd resin short medium long and very long four kinds of oil degree?

Extension of the meaning of alkyd resin oil content 2.1 the meaning of oil content and fatty acid content The meaning of oil content (OL) is the ratio of the amount of oil Wo in the alkyd resin formula to the theoretical yield Wr of the resin, expressed in%: OL = W o / W r% When alkyd resin is directly synthesized from fatty acid, the corresponding fatty acid content "OL f is the ratio of the amount of fatty acid W f in the formula to the theoretical yield of the resin, also expressed in%: OL f = W F /W r% in order to facilitate the analysis and comparison of formulas, OL f can be converted into OL, and the fatty acid group content in oil and fat is 96%, so: OL f = OL × 96%. however, this is only a reduced comparison, not the fatty acid added in the fatty acid method reacts with glycerin to generate oil and fat, even in the fatty acid method alkyd resin, it is also possible that the polyol does not use glycerin at all. So, what is the significance of OL or OL f for the characterization of alkyd resin formulations?

It is well known that for a long time after the advent of alkyd resin, alkyd resin is generally synthesized from polybasic acids such as oil, polyol and PA, and its structure consists of two units: polyester main chain and fatty acid side chain. Therefore, OL has the following characterization significance for alkyd resin formula: (1) It indicates the content of weak polar structure in alkyd resin, because long chain fatty acid is much weaker than polyester and the content of weak polar structure, it directly affects the solubility of alkyd resin, such as long oil alkyd soluble in solvent gasoline, medium oil alkyd soluble in xylene, short oil alkyd soluble in xylene or xylene/ester mixed solvent, which also affects brushing and leveling properties, has high content of weak polar structure, and has good brushing and leveling properties. (2) Indicates the content of flexible components in alkyd resin, because long chain fatty acid is a flexible structure, while phthalic anhydride polyester is a rigid structure, OL also reflects the Tg of the resin, or often said "soft and hard degree". The expansion of the meaning of 2.2 oil degree With the continuous expansion of the use of alkyd resin and the increasing diversification of raw materials, specifications and varieties, some questions have been raised about the characterization significance of OL. The following are the formulas of alkyd resin A and B: abbreviations and specifications of raw materials in the formula: DEG (diethylene glycol), GL (glycerol) 100%, BA (benzoic acid) 100%, R (rosin), AV168.3, PA (phthalic anhydride) 100%, soybean oil fatty acid, average molecular weight 273.4. Here is a special description of pentaerythritol (PE) , industrial pentaerythritol has a variety of specifications, coating with pentaerythritol is not pure, it is composed of single pentaerythritol (MPE) and two pentaerythritol (DPE) and a small amount of impurities. MPE is a tetrahydric alcohol with a hydroxyl equivalent weight of 34.0 and DPE is a hexahydric alcohol with a hydroxyl equivalent weight of 42.33. For pentaerythritol used in general coating industry, MPE is 86% (mass%), DPE is about 12%, hydroxyl equivalent is about 35.5, and the average hydroxyl functionality f can be calculated to be about 4.15. Therefore, it is wrong to regard the functionality of industrial pentaerythritol as 4.0 in the formula calculation of alkyd resin in the past. Generally, it can be determined as 4.15. This is not very accurate, but it is more realistic than taking 4.0. It should also be noted that in the past, when calculating and analyzing the formula of alkyd resin, the item "glycerin in oil" was often listed. In this paper, mo, ea and eb of grease were listed as two items, and item G represented glycerin and item F represented fatty acid, which should be relatively simple and clear.