Color paste dispersant usage guide: Let the color bloom evenly

In the production process of coatings, inks, plastics and other industries, color paste dispersants are key additives to achieve uniform dispersion of pigments and ensure the color quality of products. However, to give full play to the role of color paste dispersants, it is crucial to master the correct usage method. From preparation before use to specific operation, every link affects the final effect. Next, I will introduce the key points of color paste dispersants in detail.

1. Preparation before use

(I) Understand the characteristics of dispersants

Different types of color paste dispersants have different chemical structures and performance characteristics, and the applicable systems and pigments are also different. For example, anionic dispersants are suitable for water-based systems and can provide electrostatic repulsion for pigment particles; non-ionic dispersants perform well in both water-based and solvent-based systems and achieve dispersion through steric hindrance effects. Before use, you must fully understand the type, scope of application, dispersion principle and related technical parameters of the selected dispersant to ensure that it matches the pigment and carrier system used.

(II) Confirm the pigment and carrier

The type, particle size, surface properties, etc. of the pigment will affect the effect of the dispersant. For pigments with smaller particle size and larger specific surface area, more dispersants are often required to achieve a good dispersion effect. At the same time, the properties of the carrier (such as resin, solvent, etc.) are also crucial. For example, in solvent-based coatings, the polarity and solubility of the solvent will affect the stability and dispersion efficiency of the dispersant in the system. Therefore, before using the dispersant, it is necessary to clarify the specific conditions of the pigment and carrier used in order to select the appropriate dispersant and determine the reasonable dosage.

(III) Determine the amount of dispersant

The amount of dispersant used is not the more the better, but needs to be accurately calculated based on the type, amount and characteristics of the pigment system. Generally speaking, the amount of dispersant used ranges from 1% to 10% of the pigment mass. In actual production, the optimal amount can be determined by small sample tests. The specific method is: prepare a series of samples containing different amounts of dispersant, conduct dispersion performance tests, such as observing the dispersion state of the pigment, measuring the viscosity of the system, evaluating the coloring effect, etc., and select the amount with the best dispersion effect and the most reasonable cost as the standard amount in production.

2. Use process of color paste dispersant

(I) Pre-dispersion treatment

Before adding the color paste dispersant to the whole system, some difficult-to-disperse pigments can be pre-dispersed first. Mix the pigment with an appropriate amount of carrier and dispersant, and perform preliminary dispersion by stirring, grinding, etc. For example, when producing high-concentration color paste, the pigment can be first mixed with part of the solvent and dispersant in a high-speed mixer to make a pre-dispersion, which can improve the efficiency and effect of subsequent dispersion.

(II) Adding dispersant

Add the pre-dispersed pigment system or directly add the pigment and dispersant to the carrier system in a certain proportion. When adding, pay attention to the way of adding the dispersant, try to avoid adding a large amount at one time, but use a slow and uniform addition method. For example, during the stirring process, slowly pour the dispersant along the wall of the stirring kettle, while maintaining a certain stirring speed to ensure that the dispersant can quickly mix with the pigment and carrier.

(III) Dispersion operation

After adding the dispersant, sufficient dispersion operation is required. Commonly used dispersing equipment includes high-speed dispersers, sand mills, ball mills, etc. Different equipment is suitable for different dispersing stages and material characteristics. High-speed dispersers are suitable for preliminary dispersing and mixing. They generate strong shear force through high-speed rotating stirring paddles to break up pigment agglomerates; sand mills and ball mills are more suitable for fine dispersing. Through the grinding and impact of grinding media (such as glass beads, ceramic beads, etc.), the particle size of pigment particles is further reduced and the dispersion uniformity is improved. During the dispersing process, the speed, dispersing time and other parameters of the dispersing equipment should be reasonably set according to the properties and dispersing requirements of the materials.

(IV) Dispersing effect detection

After the dispersing operation is completed, the dispersing effect needs to be detected. Commonly used detection methods include visual observation, particle size analysis, viscosity measurement, etc. Visual observation can intuitively determine whether the pigment is evenly dispersed, whether there are agglomerates and precipitation; particle size analysis uses laser particle size analyzers and other equipment to accurately measure the particle size distribution of pigment particles and evaluate the fineness of dispersion; viscosity measurement can reflect the fluidity and dispersion state of the system. Generally speaking, the viscosity of a well-dispersed system is relatively stable and within the expected range. If the test finds that the dispersion effect is not ideal, it is necessary to analyze the reasons, adjust the amount of dispersant or the dispersion process, and re-disperse the operation.

3. Precautions during use

(I) Environmental and equipment requirements

The ambient temperature and humidity of the color paste dispersant will have a certain impact on the dispersion effect. Generally speaking, the suitable operating temperature is between 20℃ - 30℃. Too high or too low temperature may affect the activity of the dispersant and the fluidity of the system. At the same time, ensure the cleanliness of the dispersing equipment to avoid impurities remaining inside the equipment affecting the dispersion effect. When changing different pigments or systems, the equipment must be thoroughly cleaned to prevent cross contamination.

(II) Safety protection measures

Some color paste dispersants may be toxic, corrosive or irritating to a certain extent. Safety protection measures must be taken during use. Operators should wear protective gloves, masks, goggles and other protective equipment to avoid contact between the dispersant and the skin and eyes. If contact is accidental, rinse immediately with plenty of clean water and seek medical attention in time. In addition, color paste dispersants should be stored in a cool, ventilated and dry environment, away from fire sources and oxidants to prevent safety accidents such as fire and explosion.

(III) Compatibility with other additives

In actual production, in addition to color paste dispersants, other additives may also be used, such as defoamers, leveling agents, stabilizers, etc. These additives may interact with each other, affecting the dispersion effect and product performance. Therefore, before use, it is necessary to conduct an additive compatibility test to ensure that there will be no adverse reactions between the additives. For example, some defoamers may destroy the stability of the dispersant and cause the pigment to reagglomerate. At this time, it is necessary to select a suitable defoamer or adjust the order and amount of addition.

Mastering the correct method of using color paste dispersants can make the pigments evenly dispersed in various systems and give the products high-quality colors and performance. Both production and processing enterprises and relevant technical personnel should pay attention to the details of the use of color paste dispersants and continuously optimize the use process to achieve better production effects and product quality. With the development of technology, the use of color paste dispersants will also be continuously improved and perfected, bringing more convenience and innovation to various industries.