Matting considerations when using matte dispersants:
1. Material compatibility
Matrix resin matching
Matte dispersants must be compatible with the chemical structure of the plastic matrix (such as PP, PE, ABS, etc.) to avoid
stratification or precipitation caused by poor compatibility. For example, if used for PC materials, a dispersant that is resistant
to high temperatures and compatible with PC must be selected to prevent decomposition during processing.
Filler/pigment selection
The filler type (such as talcum powder, calcium carbonate) and pigment particle size must match the dispersant to avoid
agglomeration or uneven dispersion. For example, fine-particle pigments (such as nano-scale) require higher molecular weight
dispersants, while coarse-particle fillers (such as 2000 mesh talcum powder) can use low molecular weight dispersants.
Additive synergy
Matte dispersants may interact with other additives (such as plasticizers and lubricants), and the synergistic effect needs to be
verified experimentally. For example, excessive lubricants may reduce the dispersant's adsorption capacity on fillers, resulting in a
decrease in matte effect.
2. Process Control
Temperature and Shear Force
If the dispersion temperature is too high, the dispersant may decompose or the filler may agglomerate. If the temperature is too
low, the dispersion efficiency will be insufficient. It is recommended to adjust the processing temperature according to the thermal
stability
of the dispersant (such as 180-220℃) and match the appropriate screw speed (such as 300-500rpm).
Dispersion Time and Order
The dispersant needs to be premixed before the filler is added to ensure that the filler surface is fully wetted. For example, premixing
the dispersant and filler for 10 minutes before adding the matrix resin can improve the dispersion efficiency.
Equipment Selection
High-speed mixers, twin-screw extruders and other equipment need to match the performance of the dispersant to avoid uneven
dispersion due to insufficient shear force of the equipment. It is recommended to use an extruder with a side feeding function to reduce
the residence time of the filler in the high temperature area.
3. Storage and Safety
Storage Conditions
Matte dispersants need to be stored in a light-proof, sealed, and moisture-proof environment to avoid high temperatures (recommended
≤40℃) or freezing environments. For example, some amine-containing dispersants are easily hydrolyzed in a humid environment, resulting
in decreased performance.
Expiration date management
Dispersants that have exceeded their shelf life may become ineffective, and the dispersion efficiency needs to be tested regularly (such as
by a particle size analyzer). It is recommended to manage inventory according to the first-in-first-out (FIFO) principle to avoid using expired
products.
Safety protection
Some dispersants contain volatile organic compounds (VOCs) or irritating ingredients, and protective equipment (such as gloves and
goggles) must be worn. GBZ 2.1-2019 "Occupational Exposure Limits for Hazardous Factors in the Workplace" and other regulations must
be followed.
4. Regulatory and environmental compliance
Food contact materials
Matte dispersants used for food packaging must comply with regulations such as GB 4806.6-2016 "National Food Safety Standard Plastic
Resins for Food Contact". For example, the EU Food Contact Materials Regulation (EU) No 10/2011 has strict restrictions on the migration of
dispersants.
Electronic and electronic products
Must meet the limit requirements for hazardous substances (such as phthalates and polycyclic aromatic hydrocarbons) in regulations such
as RoHS 2.0 and REACH. It is recommended to choose dispersants that have passed UL certification or third-party testing.
VOCs emission
Some matte dispersants contain solvent-based ingredients and must comply with GB 37822-2019 "Volatile Organic Compounds Unorganized
Emission Control Standard". Water-based or solvent-free dispersants are preferred.
5. Performance Verification and Testing
Matte Effect Evaluation
The surface gloss is measured by a gloss meter (such as a 60° angle), and the target value is usually 10-30 GU (gloss unit). It is necessary to
compare with samples without dispersant to ensure that the matte effect is significantly improved.
Stability Test
Test the storage stability (such as sedimentation test) and thermal stability (such as 180℃/30 minutes heat aging) of the dispersion system.
It must comply with mechanical property test standards such as ISO 178.
Application Test
Verify the effect of dispersants on processing properties (such as melt flow rate) and product properties (such as impact resistance) in actual
production.
For example, detect whether flow marks or bubbles appear in injection molding.
6. Common Problems and Solutions
Uneven Matte Effect
Reason: Insufficient dispersant dosage or filler agglomeration.
Solution: Increase the amount of dispersant (such as 0.5-2.0%).
Color spots appear on the surface of the product
Reason: Uneven dispersion of pigments.
Solution: Optimize the premixing process and extend the mixing time.
The melt viscosity is too high during processing
Reason: Insufficient thermal stability of the dispersant.
Solution: Replace the high-temperature resistant dispersant and reduce the processing temperature.
Dispersant stratification during storage
Reason: Improper storage conditions.
Solution: Store in a sealed and light-proof environment and stir regularly.
Summary
The application of matte dispersants needs to be controlled from the entire chain of materials-processes-regulations, and ensure that the
performance meets the standards through experimental verification and standardized testing. It is recommended to cooperate with
dispersant suppliers to customize the formula according to specific application scenarios and regularly evaluate the long-term stability
of dispersants.
