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High-speed dispersers and mixers are both equipment used to mix materials, but they have significant differences in working principles, structural characteristics, applicable objects and final effects. The choice of equipment depends mainly on the nature of the materials and process requirements
一．Core Differences
Main Objectives/Functions:
High-speed dispersing machine: The core goal is to disperse, especially to quickly and uniformly disperse solid powders into liquids such as resins and solvents, and to break the agglomerates of powders. It pursues high shear forces to achieve uniform distribution and stability at the microscopic level.
Mixer: The core goal is to mix, so that two or more materials achieve a macroscopic uniform mixing. It focuses on the overall flow and circulation of the material, and the shear force is usually much lower than the disperser.
Working principle and shear force:
High-speed dispersing machine: relies on high-speed rotating serrated disc impellers (dispersing disks) to produce powerful shear, impact and turbulence. The serrated edge violently tears and cuts the material, resulting in a huge velocity gradient, thus effectively breaking up the powder agglomerate and realizing the wetting and primary dispersion of the powder in the liquid.
Mixer: It relies on blades rotating at a relatively low speed (such as paddle stirring paddles, anchor type, spiral type, turbine type, etc.) to push materials to form a macroscopic circulation flow in the container. Its main functions are mixing, heat transfer, mass transfer, settling prevention, etc. The shear force is weak, which is not enough to effectively disperse powder with high hardness or easy agglomeration.
Structure and components:
High-speed dispersion machine: The core components are a high-speed motor-driven dispersing shaft/dispersion blade and a serrated disc dispersing disc at the end. Usually designed to be raised and lowered for easy operation and cleaning at different levels. The structure is relatively compact.
Mixer: The core components are the motor-driven mixing shaft and various forms of mixing paddles. Depending on demand, it may be equipped with baffles, deflectors and other components to assist mixing. There are various forms (top-entry mixers, side-entry mixers, bottom-entry mixers, etc.), and the structure may be more complex than that of dispersers.
Applicable material status:
High-speed dispersion mixer: It is most suitable for processing liquid-solid mixtures with medium and low viscosity (the initial viscosity is usually not high), especially good at processing powders that are difficult to disperse. The mixing efficiency is low for processing high viscosity materials or pure liquids.
Mixer: Wider applicability, can handle a variety of materials from low viscosity to very high viscosity (liquids, pastes, slurries, etc.), as well as liquid-liquid mixing. However, it is inadequate for scenarios that require strong dispersion of insoluble powder. Often used for car paint mixing machine
Ⅱ. The Main Advantages of the Two and the Differences in Application Scenarios
2.1. Advantages and application scenarios of high-speed dispersers
Advantages:
Super dispersion ability: It is specially designed for breaking up powder aggregates and achieving microscopic uniform dispersion, with high efficiency and good effect.
High shear force: It can effectively wet powder materials that are difficult to infiltrate.
High efficiency: When it comes to dispersing powders, the speed is usually much faster than ordinary mixing.
The structure is relatively simple, and the operation and maintenance are convenient (especially for small laboratories or production).
The cost is relatively low (compared to other high-shear equipment that can achieve the same dispersion effect).
Main Application Scenarios:
Paint and ink industry: pre-dispersion of pigments and fillers (key steps before grinding).
Adhesive industry: dispersion of fillers and pigments.
Cosmetics industry: dispersion of powders (such as titanium dioxide and toner) in emulsions and creams.
Food Industry: Dispersion of powdered additives (e.g. colors, flavor powders, stabilizers) in liquids.
Pharmaceutical industry: premixing and dispersion of pharmaceutical active ingredients and excipients.
Battery industry: preliminary mixing and dispersion of lithium battery slurry (active material, conductive agent, binder).
Chemical Industry: Dispersion of dyes, catalysts, nano materials, paint mixing station,etc.
2.2. Advantages and Application Scenarios of Mixers
Advantages:
Versatility: Suitable for a wide range of mixing tasks (liquid-liquid mixing, solid-liquid dissolution/suspension, solid-solid mixing, heat transfer, homogenization).
The viscosity is suitable for a wide range: from watery liquids to extremely high viscosity pastes and dough can be processed.
Gentle mixing: friendlier to shear sensitive materials.
Good heat and mass transfer ability: commonly used in reaction, dissolution, crystallization, extraction and other processes.
Prevent settling/delamination: It works well to keep the mixture suspended.
Rich types of paddles: the best paddles can be selected according to different needs.
Main Application Scenarios:
Chemical reaction: mixing and mass transfer of materials in various chemical reaction kettles.
Dissolution and dilution: solids are dissolved in liquid, and liquid is diluted.
Suspension preparation: Keep the solid particles uniformly suspended in the liquid.
Food and beverage: blend syrup, mix juice, make sauce, mix dough, stir cream, etc.
Pharmaceutical: Prepare solution and suspension, react and mix.
Water treatment: flocculant mixing, sludge stirring.
Daily chemicals: A mixture of shampoo, shower gel and detergent.
High viscosity material handling: such as resin mixing, adhesive mixing, dough mixing,color mixing formula,paint mixing for cars.
Ⅲ. How to Choose During Coating Production
3.1. Key Points for Selecting High-speed Dispersers in Coating Production
Necessity: A high-speed disperser must be used in the pigment dispersion stage! This is the core equipment to ensure the quality of coatings.
Key parameters for selection:
Power and torque: selected according to batch size, material viscosity and pigment type. Insufficient power will lead to low dispersion efficiency and substandard fineness.
Dispersion disc diameter vs. linear velocity: The linear velocity at the edge of the dispersion disc is key. A serrated dispersion disk is standard.
Lifting and speed regulation: It must have hydraulic or electric lifting function to adapt to different liquid levels, and use a lower speed to prevent splash in the initial stage of dispersion. Stepless speed regulation is a must.
Tank matching: The diameter of the dispersion plate and the tank diameter must be matched. The tank bottom is preferably designed as a dish bottom or a flat bottom with baffles to promote material circulation.
Explosion-proof requirements: When producing solvent-based coatings, motors, electrical appliances, and lifting systems must meet explosion-proof level requirements.
Application scenarios:
Pigment pre-dispersion of all liquid coatings containing pigments/fillers (latex paint, industrial paint, wood paint, automotive paint, ink, etc.) (necessary process before grinding).
Low-end coatings that do not require high fineness may only use a high-speed disperser to meet the requirements, eliminating the need for grinding steps.
Preliminary dispersion of partial nanoslurries.
3.2. Key Points for Mixer Selection in Coating Production
Usage stage: The main equipment in the paint mixing stage.
Key Parameters and Types of Model Selection:
Mixing Blade Type (most important):
Propulsion type/inclined vane turbine type: suitable for mixing medium and low viscosity paints, producing strong axial flow and high mixing efficiency. Commonly used.
Paddle type: suitable for medium and low viscosity, simple, but the mixing efficiency is relatively low, and it is easy to delaminate.
Anchor/Frame: Designed for high/very high viscosity. The paddle shape conforms to the tank wall, scraping the wall surface to prevent the material from adhering and crusting, and promoting the overall flow and heat transfer. It is the first choice for increasing viscosity coatings.
Double-shaft combination type: one shaft is equipped with a dispersion disk and one shaft is equipped with a frame paddle, which takes into account both dispersion and mixing, and is suitable for more complex formulas.
Rotational Speed: The paint mixing stage usually requires medium and low speed to avoid excessive shear and bubble generation. Lower rotation speed at high viscosity.
Baffle: Installing baffle in the tank can effectively eliminate swirling, enhance turbulence and improve mixing efficiency, especially in medium and low viscosity materials.
Sealing: Solvent-based coatings need to choose mechanical seals to prevent solvent volatilization and leakage.
Heat Transfer Requirements: If cooling or heating is needed, consider whether the jacket, coil and blades can promote heat transfer.
Explosion-proof Requirements: For the same high-speed dispersing machine, solvent-based environments must be explosion-proof.
Application Scenarios:
Thoroughly mix the dispersed color paste with the base resin/emulsion, solvent/water, leveling agent, defoaming agent, thickener, film-forming auxiliary, etc.
Adjust the color, viscosity, rheological properties of the final product.
Resin Synthesis.
Ⅳ. Typical Coating Production Equipment Configuration Plan
Standard liquid coatings (latex paint, industrial paint, etc.):
Dispersion step: high-speed continuous dispersion mixers (pre-dispersed pigment/filler).
Grinding step: sand mill or basket mill (grinding the predispersion to a predetermined fineness).
Paint mixing step: stirring tank (medium and low viscosity) or anchor stirring tank (high viscosity) with propulsion/turbine stirring paddle. The ground color paste, emulsion/resin, auxiliary agent, solvent/water are evenly mixed.
High viscosity coatings (putty, thick coatings):
Dispersion/mixing process: A powerful planetary mixer or double-shaft mixer (dispersion plate + frame paddle) is often used to complete filler dispersion and base material mixing in one step. You can also use a high-speed disperser to pre-disperse the powder first, and then transfer it to a paint mixing tank with an anchor paddle to mix resin, etc.
Solvent-based coating: Regardless of whether it is a disperser or a mixer, you must choose a complete set of explosion-proof disperser machine or explosion-proof paint mix machine.
Ⅴ. Common Misunderstandings and Precautions
1. “A high-power mixer can be used to disperse pigments instead of a disperser.”
Error! The shear force of the mixer is far from sufficient to effectively disperse the pigment, which will lead to unqualified fineness, poor tinting power, and poor storage stability (settling, coarsening).
2. “When mixing paint, the higher the speed, the faster the mixing, the better.”
Error! Too high rotation speed will introduce too many bubbles (difficult to eliminate) and may destroy the dispersed pigment structure or polymer additives.
Conclusion: In coating production, high-speed disperser and mixer are key equipment that complement each other and perform their own duties. According to the different process requirements of dispersion and paint blending, accurate selection combined with material viscosity, production scale and safety requirements can ensure paint quality, production efficiency and operational safety. Looking for the high-speed disperser in the dispersion stage and selecting the right mixer type based on viscosity in the paint mixing stage are the basic principles for the selection of paint equipment.
