颜料、分散剂的结构及分散剂的作用

The structure of pigment and dispersant and the effect of dispersant

0 引言

0 Introduction

涂料广泛应用于我们的日常生活中，对被涂件起到了保护、装饰及特殊功能作用。涂料主要由成膜物质（树脂）、颜填料、助剂和溶剂（或水）组成。随着工业的发展与生活水平的提高，颜料被越来越多地应用到涂料油墨工业当中，以赋予更好的表观效果。与染料不同，颜料通常不溶于所使用的介质，大多数情况下都是以聚集体的方式存在。要得到好的着色力、遮盖力及色度等，必须将颜料的聚集体打开并保持稳定。如果颜料没有分散好，许多缺陷就有可能发生，如：絮凝、失光、颜色偏移、浮色/发花、沉淀等。本文介绍了颜料及分散剂的结构，以及分散剂在颜料分散时所起的作用。

Coatings are widely used in our daily life and play a role in protection, decoration and special functions for coated parts. Coatings are made up of film-forming materials (resins), pigments and fillers, auxiliaries and solvents (or water). With the development of industry and the improvement of living standards, pigments are more and more used in the paint and ink industry to give better appearance. Unlike dyes, pigments are usually insoluble in the medium used, and in most cases exist as aggregates. To achieve good coloring power, covering power and chromaticity, the pigment aggregates must be opened and kept stable. If the pigment is not well dispersed, many defects may occur, such as flocculation, loss of gloss, color deviation, floating / blooming, precipitation, etc. The structure of pigment and dispersant and the role of dispersant in pigment dispersing are introduced in this paper.

1 颜料的形态及粒径

The morphology and particle size of 1 pigments

在涂料中，颜料大多被制成悬浮液使用。

In coatings, pigments are mostly used as suspensions.

颜料的粒径范围分布很宽，一般从0.05 μm到1 mm之间。但研究表明，当颜料的粒径在0.05 ~ 0.50 μm之间时，具有最佳的着色力、光泽、遮盖力和耐候性等。图1显示了不同颜料粒径的对比。

The particle size distribution of pigment is very wide, ranging from 0.05 M to 1 mm. However, the results show that when the particle size of the pigment is between 0.05 and 0.50 micron, it has the best coloring power, gloss, covering power and weather resistance. Figure 1 shows the comparison of the size of different pigments.

颜料制造过程中形成的最小粒子称为原始粒子，它以单晶体或者一组晶体存在，粒径非常小。而原始粒子之间以面和面相结形成的团块，称为聚集体，聚集体比较紧密，一般的分散设备很难将其分散成原始粒子。而原始粒子和聚集体通过范德华力结合在一起，形成的较大颜料粒状团块，称为附聚体。附聚体粒子之间以点、边、角相接触，粒子间作用力小，可通过机械的力量将其分散成原始粒子或聚集体，见图2。

The smallest particles formed in the pigment manufacturing process are called primitive particles, which exist as single crystals or a group of crystals with very small particle sizes. The lumps formed by the surface and face between the original particles are called aggregates, and the aggregates are relatively tight. The general dispersing equipment is difficult to disperse them into original particles. The larger particles of pigment and particles formed by the combination of primitive particles and aggregates through fan Edward force are called agglomerates. The particles are in contact with the point, edge, and angle, and the force between particles is small. It can be dispersed into the original particles or aggregates by mechanical force, as shown in Figure 2.

我们希望颜料分散后成为原始粒子的悬浮液（理想状况），至少也是聚集体和原始粒子的悬浮液。但体系的趋势是从高能态恢复到低能状态，故以微细颗粒分布的颜料容易聚集成絮凝体。从结构上看，絮凝体与附聚体非常相似，但絮凝体中颜色之间是树脂溶液而不是空气。分散剂的存在会阻止或减缓絮凝的发生。

We want the pigment to disperse into a suspension of the original particles (ideally), at least aggregates and suspensions of the original particles. But the trend of the system is to recover from the high energy state to the low energy state. Therefore, the pigment distributed by fine particles is easy to aggregate into flocs. Structurally, flocs are very similar to agglomerates, but the color of flocs is resin solution rather than air. The presence of dispersant will prevent or slow down the occurrence of flocculation.

2 颜料的分散过程

The dispersing process of 2 pigment

颜料的分散过程由润湿、分散、稳定3个步骤组成。润湿过程中，颜料表面的的空气和水气被树脂溶液所替换，固/气两相（颜料/空气）被转换成固/液两相（颜料/树脂溶液）。分散剂尤其是低分子型的润湿分散剂能加快润湿的过程。分散过程中，主要依靠机械能作用（冲击和剪切力），颜料的团聚态被打碎成较小的微粒，成为分散状态（均匀分布）。第三步是稳定的过程，分散剂用于保持颜料分散状态的稳定，阻止失控的絮凝，并依据颜料表面所吸附的黏结剂种类和分子结构，促使悬浮液获得稳定状态。分散剂尤其是高分子分散剂对颜料粒子的稳定起了很大的作用。

The dispersing process of pigment consists of 3 steps: wetting, dispersing and stabilizing. During the wetting process, the air and water on the surface of the pigment are replaced by a resin solution, and the solid / gas phase (pigment / air) is converted into solid / liquid two phases (pigment / resin solution). Dispersants, especially low molecular wetting and dispersing agents, can accelerate the wetting process. In the process of dispersion, the aggregate state of the pigment is broken into smaller particles by mechanical energy (impact and shear force), and it becomes a dispersed state (uniform distribution). The third step is a stable process, the dispersant is used to maintain the stability of the dispersion of the pigments, to prevent the uncontrolled flocculation, and to promote the stability of the suspension based on the types and molecular structure of the binder adsorbed on the surface of the pigment. Dispersants, especially polymer dispersants, play an important role in the stability of pigment particles.

3 分散剂的作用

The effect of 3 dispersant

分散剂在涂料生产中发挥了非常重要的作用。分散体系的稳定能避免诸多的涂料问题及漆膜弊病，如果配方合理，适量地添加分散剂能够有效降低成本，改善涂料性能。

Dispersants play a very important role in coating production. The stability of the dispersion system can avoid many paint problems and paint film defects. If the formula is reasonable, a proper amount of dispersing agent can effectively reduce the cost and improve the performance of the coating.

3.1 提升光泽，增加流平效果

3.1 improve the luster and increase the leveling effect

有试验表明，完全相同的配方，采用不同的分散剂，得出的漆膜光泽会有明显的差别。例如，在某黑色卷材涂料体系中，不同的3种分散剂制得的涂料涂膜的20°光泽分别是69.7%、81.5%、77.1%。如果所采用的分散剂不恰当，颜色絮凝后变粗，其对光泽所起的作用类似于消光粉，自然会影响光泽。

Experiments show that the varnish of the paint film can be distinctly different by using the same formula and using different dispersants. For example, in a black coil coating system, the 20 degree gloss of the coatings prepared by three different dispersants are 69.7%, 81.5% and 77.1% respectively. If the dispersant used is inappropriate and the color becomes coarser after flocculation, its effect on the gloss is similar to that of matting powder, which will naturally affect the gloss.

3.2 防止浮色发花

3.2 to prevent floats

防止浮色发花，是大家所熟知的分散剂的作用之一。选用合适的分散剂，无论是罐内浮色发花还是漆膜的浮色发花，都可以得到改善或消除。图3显示的是采用不同的分散剂制得的蓝漆与白漆按相同比例混合均匀后所得出的罐内浮色发花的结果。还有些分散剂，例如SN-2004，是受控絮凝类的分散剂，分子链中含有一些羧基基团，与颜料亲和的同时，还会互相形成氢键，从而使颜料粒子稳定，达到预防浮色发花的效果。

Preventing floating color is one of the most widely known dispersants. The appropriate dispersant can be improved or eliminated in both the floating color and the floating color of the paint film. Figure 3 shows the result of the float in the tank when the blue paint and the white paint are mixed evenly in the same proportion with different dispersants. Some dispersants, such as SN-2004, are the dispersants of controlled flocculation. There are some carboxyl groups in the molecular chain. While affinity with the pigment, hydrogen bonds are formed to make the pigment particles stable and achieve the effect of preventing floats.

3.3 提高着色力

3.3 improve the coloring force

颜料分散和稳定得更好，其着色力会明显加强。图4显示的是采用不同的分散剂分散的黑浆，与白漆按相同的比例混合后的涂膜结果，可以明显看出其着色力的差别。

The pigment is dispersed and stabilized better, and its coloring power will be significantly enhanced. Figure 4 shows the use of different dispersant dispersed black pulp, and the results of the coating on the same proportion with the white paint can clearly show the difference of its coloring force.

3.4 降低黏度，增加颜料载入量

3.4 reduce viscosity and increase the volume of pigments

采用合适的分散剂，所得的色浆黏度会明显降低。这样可以增加颜料的载入量，提高生产效率。图5是采用不同分散剂分散的大红色浆的黏度对比。

With appropriate dispersant, the viscosity of the resultant pigment will be significantly reduced. This can increase pigment loading and improve production efficiency. Fig. 5 is the viscosity contrast of the large red paste dispersed with different dispersants.

3.5 减少絮凝，增加施工性和使用性

3.5 reduce flocculation, increase constructability and usability

许多人在评估分散剂时，都会做指研试验。如果分散剂搭配不恰当，指研的区域与未指研的区域会产生明显的色差，絮凝后的颜料着色力会下降，这给调色及涂料施工都带来困难。采

Many people do finger pointing tests when evaluating dispersants. If the dispersant is not matched properly, the area of the research and the unstudied area will have obvious chromatic aberration, and the pigmentation after flocculation will decrease, which brings difficulties to the color adjustment and the construction of the paint. Mining