Basics of Alkyd Resin Technology

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.

Alkyd figure one updated

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:

Alkyd 2

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:Alkyd 3

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.

Alkyd 4Alkyd 5

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.

UV-LED固化涂料提供高速光固化过程

UV-LED固化涂料提供了一种高速光固化工艺,与传统的固化工艺相比有许多优点. Multiple advantages include High speed, lower energy requirements, little or no VOC, less production space, less dirt collection, high quality finish, rapid processing 以及一些紫外线技术的即时开关也加快了生产和节能. UV Curable 油漆自20世纪60年代以来就已经存在了,它是基于包括自由基和阳离子引发的链式聚合反应. As the majority of coatings for UV cure coating utilize free radical polymerization (>90% of market), 本文主要讨论由光引发剂引发的自由基聚合(图. 1):

Figure 1 Rev

在UV/EB固化涂料中使用的不饱和类型如表I所示, with by far the largest type being acrylate.

Table I – Type of Unsaturation used in UV/EB Cure
Table I – Type of Unsaturation used in UV/EB Cure

Photoinitiator

主要考虑光引发剂吸收曲线的两种不同特性. First, PI和second所吸收的光的最大波长(λ Max)是多少, 吸收强度(摩尔消光系数). Photoinitiators 在300 nm到450 nm的长波波长下,用于固化着色膜的研究通常比用于固化透明配方的研究具有更高的摩尔消光系数. To maximize cure and efficiency, 由于不同的灯有不同的光谱输出,PI的吸光度必须与灯的光输出相匹配(见表一). 在较厚的涂料中,波长较长的光对增强固化也很重要. 新的PI也使色素涂料的配方成为可能,除了透明涂料. The general cure considerations influenced by color, PVC, 图中总结了颜料颗粒大小和膜厚. 2:

Figure 2 – UV Cure Considerations
Figure 2 – UV Cure Considerations. Image: Ciba – Geigy literature

There are two main types of free radical photoinitiators, Type I and Type II. I型光引发剂在照射下发生裂解,形成两个自由基. 正常情况下,这些自由基中只有一个具有活性,从而引发聚合. 1-羟基环己基苯基酮是一种应用广泛的I型PI. II型光引发剂在照射后形成激发态, 从供体分子中提取一个原子或电子(增效剂). The donor molecule in turn initiates polymerization. 广泛使用的II型光引发剂的一个例子是二苯甲酮. Tertiaryamines 当它们与二苯甲酮反应时通常用作增效剂, and also retard the inhibition of polymerization by oxygen. 当需要考虑气味和可萃取性时,使用丙烯酸叔胺化合物. Oxygen can also inhibit cure especially in thin films; to counteract oxygen inhibition, coatings can use amine synergists, be cured under a nitrogen atmosphere, employ the addition of wax, high initiator concentration, more intense UV Light, and/or surface active initiators.

 

To read the rest of the article, written by 十大彩票平台’ President, Ron Lewarchik, click over to UL Prospector here.