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Laboratory dispersers mainly work through high-speed rotating dispersion disks (impellers). The process can be divided into three stages:
Mixing: At low speed, powdered pigments (such as titanium dioxide, carbon black) are preliminarily mixed into liquid base materials (resin, solvent) to form a paste to prevent the powder from flying.
Dispersion: The core stage. High-speed rotating dispersion discs produce powerful shear and impact forces:
Shear force: The high linear velocity at the edge of the dispersion disk tears and breaks the pigment agglomerates apart.
Impact force: The materials are thrown to the inner wall of the container at high speed, colliding and rubbing with each other, further breaking the particles.
Refining: Maintain high-speed dispersion so that the pigment particles reach the desired fineness and are stably distributed in the resin system to form a uniform and stable suspension.
Laboratory dispersers mainly come in the following forms:
Lifting disperser
Features: This is the most common and standard laboratory model. The motor and transmission mechanism are installed on the bracket that can be vertically raised and lowered, and the dispersion disk can be raised and lowered by hand or electric mode, which is convenient to operate in containers of different sizes and depths, and also convenient to take and place containers and clean them.
Advantages: Wide applicability and flexible operation, it is the “universal” standard equipment of the laboratory.
Handheld dispersing machine
Features: Also known as high speed dispersion homogenizer. The motor is integrated in the handle and the dispersion shaft is directly connected to the dispersion head (usually a rotor-stator structure). Handheld deep into the container for dispersion during operation.
Advantages: Relatively cheap, very portable, suitable for processing samples of smaller volume (tens of milliliters to several liters), stronger shear force, especially suitable for processing samples with high viscosity or requiring emulsification.
Disadvantages: The stability is not as good as the fixed type, the operation is laborious, it is difficult to accurately control the dispersion depth and consistency, and the safety is slightly lower.
Basket sand grinding and dispersing machine
Features: This is a more advanced laboratory equipment. It combines both dispersing and grinding functions. The equipment has a liftable “basket” with grinding media (such as fine zirconium beads) inside. When working, the basket drops to immerse in the material, and rotates at high speed to complete the dispersion and grinding at the same time.
Advantages: One device replaces two devices of disperser and sand mill, which is especially suitable for samples that need to reach extremely fine particle sizes (such as nanoscale). Space saving and easy to clean (no need to clean up pipes and beads like a traditional sand mill).
Disadvantages: Expensive.
Choosing a suitable dispersing machine for the laboratory requires consideration of the following factors:
Batch Size: This is the primary factor. Choose the power of the motor and the size of the dispersion tray according to the sample volume you routinely process (ranging from 100mL to 5L). The power range is typically between 0.2 kW and 1.5 kW.
Material Viscosity (Viscosity): A motor that requires more torque and power to handle high Viscosity materials to prevent motor overload shutdown.
Speed Range: A wide range of stepless speed regulation (e.g. 0-3000 rpm or higher) is essential in order to find the best speed for materials at different stages (mixing, dispersing) and with different viscosities.
Lifting mode Lifting Mechanism:
Manual lifting: economical and affordable.
Electric lifting: the operation is more labor-saving, smooth and high-precision, which is standard for high-end models.
Control & Display:
Basic Type: Digital Display RPM.
Advanced type: Color touch screen, programmable (store multiple process recipes, automatically perform speed up, constant speed, and speed down processes), with torque display/recording. The torque reading is very important. It can reflect the viscosity change of the material in real time, help judge the dispersion end point and ensure the repeatability of the experiment.
Safety Features: Emergency stop button, overload protection, motor overheating protection, etc. are necessary.
Accessories: Find out whether the equipment provides dispersion trays of various specifications, containers of different materials (stainless steel, plastic), etc.
Personal protection: Protective goggles, gloves and lab coats must be worn to prevent material splashing.
Container securement: Make sure the beaker or container is securely clamped or placed right in the center of the lift table to prevent the container from moving or tipping.
Correct immersion: The dispersion plate should be placed in the center of the liquid level, and the depth is generally 1/2 to 2/3 of the diameter of the dispersion plate. Too shallow creates swirls and splashes, and too deep is inefficient.
Start sequence: Always start the motor first, let the dispersion pan rotate at low speed, and then slowly immerse it into the material. It is absolutely forbidden to suddenly start the high speed after inserting the stationary dispersion disk directly into the material, which will lead to violent splashing of the material and is extremely dangerous.
Speed control: Start from low speed and gradually increase the speed to avoid “storm boiling” phenomenon.
In summary, the laboratory paint disperser is the “heart” equipment of paint research and development. The selection should not only pursue power and speed, but should pay more attention to the accuracy of its control, the recordability of data, and the safety and convenience of operation, which are crucial to obtaining reliable and reproducible experimental data
Laboratory equipment:
Processing capacity: Small batch (0.2 ml-10L), suitable for laboratory scale.
Application scenarios: R&D, formula testing, small batch production (such as coating formula development, nanomaterial dispersion).
Industrial Equipment:
Processing capacity: Large batch (tens of liters to several tons), suitable for industrial production.
Application scenarios: mass production in coatings, inks, food, medicine and other industries (such as mass production of coatings, food emulsification).
Laboratory equipment:
Structure: Compact, lightweight, with hydraulic lifting structure, easy to move and clean.
Material: Stainless steel (SUS304/316L) or corrosion-resistant materials are often used in contact with materials to ensure the purity of samples.
Design Features: Easy to clean, suitable for frequent change of material types.
Industrial Equipment:
Structure: Strong and durable, with mechanical lifting or fixed structure, heavy material (such as carbon steel or stainless steel).
Material: Wear-resistant and corrosion-resistant, equipped with explosion-proof motor and sealing structure for flammable and explosive materials.
Design Features: Supports continuous work and reduces manual intervention.
Laboratory equipment:
Rotational speed: High rotational speed (10,000-30,000 rpm), stepless speed regulation (such as variable frequency speed regulation), high precision.
Power: Low power (800W-4kW), suitable for small batch processing.
Control mode: manual or simple automatic control, flexible adjustment of parameters.
Industrial Equipment:
Rotational speed: The rotational speed is lower (500-3000rpm), but the shear force is stronger, focusing on efficiency.
Power: High power (several kW to tens of kW), strong driving ability, handling high viscosity materials.
Control mode: Automatic control system (such as PLC), supporting remote monitoring and continuous production.
Laboratory equipment:
Safety: Meets laboratory safety standards, equipped with overload protection and emergency stop function.
Maintenance: Easy to clean, easy to replace parts.
Industrial Equipment:
Safety: Explosion-proof design (for solvent-based materials), sealing structure to prevent leakage.
Maintenance: Regularly check the motor, seals and dispersion discs to ensure stable operation for a long time.
Laboratory equipment:
Cost: Lower, suitable for R&D budget.
Investment: Short-term use, high flexibility.
Industrial Equipment:
Cost: Higher, but high efficiency for long-term use.
Investment: Long-term production demand, long payback period.
Q1: What is the main difference between a laboratory disperser and a production disperser?
A: The core differences are accuracy, controllability and data logging capabilities. Rather than production efficiency, laboratory equipment focuses on simulating processes and providing quantifiable data (such as torque/energy input) to guide production.
Q2: How to judge whether the dispersion has reached the end point?
A: The empirical method is that the scraper fineness meter reaches the target value. A more scientific method is to observe that the torque value is stable in a plateau period, indicating that the particles can no longer be further refined and the energy consumption tends to be stable.
Q3: Why is the equipment of well-known brands expensive? Is it worth it?
A: Its value is reflected in excellent stability, precise motor control (ensuring consistent speed/torque in each batch of experiments) and globally recognized data authority. For laboratories pursuing R&D accuracy and patent applications, the investment is worth it.
