浅谈润湿分散剂在涂料配方中的选用
Discussion on the selection of wetting and dispersing agent in coating formula
涂料配方设计中,润湿分散剂对于润湿和分散效果非常重要。要选择合适的润湿分散剂,则需要在设计研磨配方之前先了解以下信息:
Wetting and dispersing agents are very important for wetting and dispersing in coating formulation design. To choose the right wetting dispersant, the following information should be known before designing the grinding formula.
涂料的应用领域:针对不同应用领域各自的特点与要求需要采用相应的润湿分散剂。
Application area of coatings: wetting and dispersing agents should be adopted in accordance with their respective characteristics and requirements in different application fields.
涂料的类型(底漆、面漆、底色漆):不同类型的涂料有 着不同的性能要求。
Types of coatings (primers, topcoat, primers): different types of coatings have different performance requirements.
系统的种类及极性:润湿分散剂必须与系统具有良好的相容性才能起作用。
The type and polarity of the system: wetting dispersant must be well compatible with the system before it can work.
颜料:颜料类型(有机/无机/效应颜料/炭黑),比表面及表面化学(酸性/碱性):不同的颜料有着完全不同的分散特点,需要与其相应的不同润湿分散剂以便在其表面形成牢固的吸附。
Pigment: pigment type (organic / inorganic / effect pigment / carbon black), compared with surface and surface chemistry (acid / alkaline): different pigments have completely different dispersing characteristics, and they need to be different wetting dispersants in order to form a solid adsorption on the surface of the pigment.
共研磨或分色研磨:前者要求一个折衷的方案,而后者则能够实现研磨条件的优化。
Common grinding or color separation grinding: the former requires a compromise solution, while the latter can achieve the optimization of grinding conditions.
有无研磨树脂:一般针对有无研磨树脂都有相应的润湿分散剂产品推荐。
Whether there is grinding resin: generally recommended for wetting and dispersing agents with or without abrasive resin.
润湿分散剂的选择简单说就是两个方面的选择:分散剂的种类与用量。与其他所有的助剂一样,润湿分散剂的正确用量十分重要。稳定颜料的润湿分散剂的用量取决于颜料的比表面积。因为分散剂必须覆盖全部的颜料表面,具有较大表面积的颜料(即较小的粒径)就需要更多的分散剂。颜料的吸油量和BET表面积可作为分散剂用量的参考依据。
The choice of wetting dispersant is simply two choices: dispersant type and dosage. Like all other auxiliaries, proper dosage of wetting dispersant is very important. The amount of wetting dispersant for stable pigments depends on the specific surface area of the pigment. Because dispersants must cover all pigment surfaces, larger dispersing agents are required for larger surface pigments (i.e. smaller size). The oil absorption and BET surface area of pigment can be used as a reference for dispersant dosage.
分散剂用量与以下几个因素密切相关
The dosage of dispersant is closely related to the following factors
与涂料的最终用途有关:出于对成本的考虑,通常建筑涂料中分散剂用量较低,而汽车涂料中则需要较高用量以获得较好的性能。
It is related to the final use of the coating: for the consideration of cost, the dosage of dispersant in the architectural coatings is usually low, and the high dosage of the automobile coating is needed to obtain better performance.
与基料的类型及化学性质有关:涂料中树脂的润湿分散作用各不相同,这会对润湿分散剂的使用量有影响。
It is related to the type and chemical properties of the base material: the wetting and dispersing effects of the resin in the coating are different, which will affect the usage of wetting dispersant.
与润湿分散剂的化学性质有关:由于相对分子质量和化学结构的原因,低相对分子质量助剂比高相对分子质量助剂添加量要低。
It is related to the chemical properties of wetting dispersants: low relative molecular mass auxiliaries are lower than high molecular weight additives because of the relative molecular mass and chemical structure.
与颜料粒径有关:透明钛白粉需要比普通钛白粉多约5~8倍的分散剂的用量。
It is related to the particle size of the pigment: the amount of dispersant used for transparent titanium dioxide is about 5~8 times higher than that of ordinary titanium dioxide.
不同相对分子质量的润湿分散剂用量
Dosage of wetting dispersant with different molecular weight
基于低相对分子质量聚合物的常规型润湿分散剂对无机颜料的用量为0.5%~2.0%,对有机颜料的用量为 1.0%~5.0%(以分散剂购入形式对颜料重量计)。按总配方计,分散剂的用量一般在 0.1%~1.0%。
The use of conventional wetting dispersants based on low molecular weight polymers for inorganic pigments is 0.5%~2.0%, and the amount of organic pigments is 1.0%~5.0% (in the form of dispersant purchase in the form of pigment weight). According to the total formula, the amount of dispersant is generally 0.1%~1.0%.
高相对分子质量分散剂的用量则要高得多,尤其对小粒度的有机颜料。因为有机颜料表面积比无机颜料表面积大得多,所以这样的高用量是必需的。对这样的用量不必担心有什么问题,因为聚合物分散剂与树脂性质相似,对漆膜的耐久性没有不利的影响。佛罗里达的户外试验、模拟耐候试验和超过十年的实际使用证明了这一点。对无机颜料,推荐的用量相当于低相对分子质量分散剂的用量水平。对无机颜料的典型用量为1%~10%;对有机颜料是10%~30% (以分散剂活性成分对颜料重量计)。对非常细粒的颜料(例如某些炭黑),用量为60%~80% 是必需的。
The dosage of high molecular weight dispersant is much higher, especially for small particle size organic pigments. Because the surface area of organic pigments is much larger than the surface area of inorganic pigments, such high dosage is necessary. There is no need to worry about such dosage, because the polymer dispersant is similar to the resin, and has no adverse effect on the durability of the paint film. The outdoor test, simulated weathering test and actual use in Florida for more than ten years have proved this point. The recommended dosage for inorganic pigments is equivalent to that of low molecular weight dispersants. The typical dosage of inorganic pigment is 1%~10%; the organic pigment is 10%~30% (with the dispersant active component to the pigment weight gauge). For very fine grained pigments (such as certain carbon black), the amount of 60%~80% is necessary.