Inorganic pigment dispersant usage guide: unlock the secret of perfect color presentation

In the world we live in, colors are everywhere, from home decoration to industrial products, from artistic creation to daily necessities, the rich and diverse colors are inseparable from the contribution of inorganic pigments. And inorganic pigment dispersants, the "behind-the-scenes heroes" in pigment applications, can help pigments perform at their best. But in order for it to really work, it is crucial to master the correct method of use. Here is a detailed introduction to the use of inorganic pigment dispersants.

Preliminary preparation: precise adaptation, lay a good foundation

Clearly define the characteristics of pigments and media

Different inorganic pigments have different chemical compositions, particle sizes, surface properties, etc., and the media are also diverse, such as water-based, oil-based, solvent-based, etc. Before using dispersants, you must fully understand the characteristics of pigments and media. For example, iron oxide pigment particles are large and the surface is highly hydrophilic. When used in oily media, it is necessary to select a dispersant with good lipophilic groups and can reduce the interfacial tension between the pigment and the oily medium; titanium dioxide pigments have strong hiding power but are easy to agglomerate. In water-based coatings, it is necessary to select a dispersant that can provide sufficient steric hindrance and electrostatic repulsion. Only by accurately matching the pigment and the medium can the dispersant play the best effect.

Determine the appropriate dosage

The amount of dispersant is not the more the better. Excessive use may cause problems such as increased foam and abnormal system viscosity, affecting the performance and stability of the product; too little dosage cannot effectively disperse the pigment. Generally speaking, the amount of dispersant depends on the type and content of the pigment and the properties of the medium. Usually, the optimal dosage can be determined through small-scale experiments. First, take a certain amount of pigment and medium, and conduct a dispersion experiment according to different dispersant dosage ratios to observe the dispersion state of the pigment, the viscosity change of the system, and the performance of the final product, so as to find the most appropriate dispersant dosage.

Optimize equipment and environment

The appropriate dispersion equipment can improve dispersion efficiency and quality. Common dispersing equipment includes high-speed mixers, sand mills, ball mills, etc. For pigments with coarse particles and easy to disperse, a high-speed mixer may be sufficient; for pigments with fine particles and easy to agglomerate, a sand mill or ball mill is required for finer dispersion. In addition, the temperature and humidity of the dispersion environment will also affect the dispersion effect. Generally speaking, dispersing operations at appropriate temperatures can improve the activity of the dispersant and the dispersibility of the pigment. For example, in a low temperature environment, the viscosity of the dispersant may increase and the fluidity may deteriorate, thereby affecting its dispersion effect.

Dispersion process: standardize operations to ensure the effect

Dispersant addition order

The order of adding dispersants has an important influence on the dispersion effect. There are usually two ways of adding: one is to mix the dispersant and the pigment evenly first, and then add it to the medium for dispersion; the other is to dissolve the dispersant in the medium first, and then add the pigment for dispersion. For some pigments that are hygroscopic or chemically reactive with the dispersant, the latter method is recommended to avoid agglomeration or deterioration of the pigment before dispersion. For example, some metal oxide pigments are prone to react with certain components in the dispersant in a humid environment, affecting the dispersion effect. In this case, it is more appropriate to dissolve the dispersant first and then add the pigment.

Dispersion process control

Stirring speed and time: During the dispersion process, the stirring speed and time need to be strictly controlled. If the stirring speed is too slow, it cannot provide enough energy to disperse the pigment particles; if the stirring speed is too fast, it may generate too much heat, causing the dispersant to fail or the pigment to deteriorate. Generally speaking, you can stir at a lower speed for a period of time to initially mix the pigment and dispersant, and then gradually increase the stirring speed to fully disperse. The dispersion time should also be adjusted according to the properties of the pigment and the medium, and it is usually necessary to determine the optimal dispersion time through experiments.

Temperature control: As mentioned above, temperature has a significant effect on the dispersion effect. During the dispersion process, try to keep the temperature stable. If the temperature is too high, the dispersant may decompose or volatilize, reducing its dispersion performance; if the temperature is too low, the viscosity of the system will increase and dispersion will be difficult. The temperature of the dispersion system can be controlled by a cooling device or a heating device.

Monitoring and adjustment

During the dispersion process, the dispersion state of the pigment and the performance of the system should be monitored in real time. The uniformity of pigment dispersion and whether there are agglomerates or precipitation can be observed visually; the size and distribution of pigment particles can also be measured using instruments such as particle size analyzers. If the dispersion effect is not ideal, the amount of dispersant, stirring speed, temperature and other parameters should be adjusted in time until a satisfactory dispersion effect is achieved.

Post-processing: Proper storage to ensure quality

Filtration and defoaming

After the dispersion is completed, there may be some undispersed pigment particles or foam in the system. In order to obtain high-quality products, filtration and defoaming treatment are required. Filtration can use equipment such as filter screens and filter cloths to remove larger pigment particles and impurities; defoaming can be done by vacuum defoaming, adding defoaming agents, etc., to eliminate foam in the system and improve the appearance quality and performance of the product.

Product storage

The dispersed pigment system also needs to pay attention to some issues during storage. Choose a suitable storage container to avoid chemical reactions between the container and the pigment or dispersant. At the same time, the container should be sealed to prevent air, moisture, etc. from entering and affecting the stability of the product. The storage environment should be kept dry and cool, avoiding direct sunlight and high temperature. Generally speaking, the storage temperature should not be too high to prevent the dispersant from failing or the pigment from agglomerating.

Regular testing

During storage, the product should be tested regularly to check whether the dispersion state of the pigment, the viscosity of the system, the color and other properties have changed. If the product is found to be abnormal, such as pigment precipitation, color lightening, etc., timely measures should be taken to deal with it, such as re-dispersion or adjustment of the formula.

The use of inorganic pigment dispersants is a systematic and meticulous process. From the preliminary preparation to the dispersion process, and then to the post-processing, every link needs to be taken seriously. Only by mastering the correct use method can the role of the dispersant be fully utilized, so that the inorganic pigment can show the most perfect color effect in various applications. I hope that the above usage suggestions can help everyone better use inorganic pigment dispersants and create a more colorful world.