Mastering the fundamentals of Alkyd Resin Technology
虽然醇酸不再是涂料中体积最大的树脂类型, they still play a significant role in the coatings industry, not only because of their versatility, 还因为他们使用了大量的可再生材料.
The term alkyd is derived from alcohol and acid.
Alkyds are prepared from the condensation reaction between polyols, dibasic acids and fatty acids. 所述脂肪酸部分来源于植物物质，是一种可再生资源. 醇酸的主要性能特点包括改善表面润湿性(从底物和颜料的生物基脂肪酸部分)和降低成本(也主要从脂肪酸部分)的能力。. The most widely used polyols 其中甘油、季戊四醇和丙三醇使用最为广泛 dibasic acids are phthalic anhydride and isophthalic acid.
Naturally-occurring oils are in the form of triglcerides. Triglycerides are triesters of glycerol and fatty acids. Triglycerides can be drying oils, but many are not. 干性油与氧反应生成1,4 -二烯. 天然产生的油是由混合甘油三酯和作为甘油分子一部分的不同脂肪酸组成的混合物.
其中一些甘油分子由较高百分比的脂肪酸和大量的非共轭不饱和二烯丙基亚甲基组成，从而提高了干燥能力. For example, linoleic acid has one active diallylic group (-CH=CH – CH2 – CH=CH -), whereas linolenic has two active methylene groups. 此外，为了提高干燥速度，醇酸可以用乙烯基改性 toluene or styrene 以增加热重，从而减少达到给定硬度所需的时间. 如果醇酸油的含量超过60%，则称为长油醇酸. If it’s between 40 and 60%, it’s known as a medium oil alkyd, 那些少于40的被认为是短油醇酸. 根据脂肪酸含量计算油长百分比的公式如下:
除油量以及醇酸功能成分的选择, 油的类型对干燥时间和性能有深刻的影响.
Fatty acids are further categorized into drying, semidrying and non-drying. 如果非共轭油的干燥指数较高，则可视为干性油, as calculated as follows, is more than 70. The higher the amount ofLinolenic and Linoleic content, the higher the drying index:
尽管干燥速度随着亚麻含量的增加而提高, 外部白色涂料的泛黄率也较大. Accordingly, 醇酸使用红花和葵花籽油，提高了抗黄变能力，因为它们的亚麻含量较低.
除了根据油的长度和脂肪酸的种类对醇酸进行分类, alkyds are also classified into oxidizing and non-oxidizing categories. 氧化醇酸通过复杂的多级自氧化机理交联, 而非氧化醇酸不交联，因此是热塑性的，除非其可用的羟基与氨基质体交联(热固化)或 isocyanate crosslinker (ambient cured).
To read the rest of the article, written by 十大彩票平台’ President, Ron Lewarchik, click over to UL Prospector here.
