Selecting the right dispersant for plastics is essential for achieving effective pigment dispersion, consistent color development, and stable polymer processing.
For manufacturers of color masterbatches, high-loading pigment concentrates, and flame-retardant compounds, poor powder wetting and pigment agglomeration can lead to black specks, inconsistent color, increased filter pressure, and processing difficulties.
Different applications require different dispersant solutions. Conventional PE wax and EBS additives, polymeric hyperdispersants, and silicone-based dispersants offer different approaches to particle wetting, dispersion, and processing performance.
So, which high-performance dispersants are best for color masterbatches, carbon black concentrates, PET pigment dispersion, and flame-retardant compounds?
This guide compares the main dispersant technologies, explains their application differences, and presents SILIKE's technical evaluations in selected polymer systems to help manufacturers identify suitable dispersant solutions for their formulations.
1. How to Choose a Dispersant for Color Masterbatches and Polymer Compounds
The best dispersant depends on the powder being incorporated, the polymer matrix, the target loading, and the downstream application. A dispersant for carbon black masterbatch may not be the right choice for PET pigment dispersion or a mineral-filled flame-retardant compound.
Use the following application guide to identify which type of dispersant may be worth evaluating. The SILIMER Dispersants grades are examples of SILIKE solutions for selected applications; they are not universal recommendations for every formulation.
| Application/search need | Common formulation challenge | Dispersant approach to evaluate | SILIKE grade example |
| Dispersants for PE/PP color masterbatches | Pigment agglomeration, shade variation, inconsistent let-down | Polymer-compatible dispersant with wetting and processing support | SILIMER 6200 |
| Carbon black dispersant for LLDPE film masterbatch | Large and fine black specks in blown film | Dispersant selected for carbon black and downstream film quality | SILIMER 6200 |
| PET pigment dispersant | High filter pressure value (FPV) | Liquid or premix-compatible pigment dispersant | SILIMER 6600 |
| Dispersants for high-loading pigment masterbatches | Difficult powder incorporation, high torque, or unstable extrusion | Dispersant matched to pigment surface, carrier resin, and process | SILIMER 6200 / 6600, depending on process |
| Inorganic pigment and filler dispersion | Poor powder wetting and distribution | Powder-form additive or suitable premix route | SILIMER 6150 |
| Dispersants for flame-retardant compounds | Powder distribution, processing, fire performance, and mechanical-property requirements | Formulation-specific dispersant screening | Selected SILIMER grades; see Section 6 |
| ATH/MDH-filled HFFR compounds | High mineral loading and extrusion challenges | Dispersant selected for mineral filler and cable-compound system | Evaluate a suitable SILIMER grade by trial |
The application examples above are starting points for technical evaluation. Final selection should be confirmed using the actual resin, powder, equipment, formulation, and product specifications.
2. How Do Dispersants Improve Pigment Wetting and Dispersion?
A pigment can be present at the correct concentration and still create visible defects when particles remain in agglomerates. Effective dispersion in polymer compounding generally involves three related stages: wetting the particle surface, breaking agglomerates under shear, and maintaining an adequate distribution during downstream processing.
As solid loading increases, particle-to-particle contacts become more frequent and less carrier resin is available relative to the powder surface area. This can contribute to higher torque or filter pressure, unstable output, color streaks, or black specks in finished film. Similar defects can have different causes, including insufficient wetting, inadequate mixing energy, carrier-resin incompatibility, or contamination.
The production route also matters. Internal mixing followed by single-screw pelletizing creates a different shear and residence-time history from twin-screw compounding. A suitable dispersant must therefore be evaluated in the context of both powder characteristics and the actual manufacturing process.
The Role of SILIKE Silicone-Based Dispersants
Different dispersant technologies work in different ways. Conventional waxes are commonly used to provide lubrication and can support powder incorporation. Polymeric hyperdispersants are designed to interact with particle surfaces and help maintain dispersion. Selected functionalized silicone-based additives may combine particle interaction, wetting support, and processing lubrication, depending on their chemistry and compatibility with the polymer system.
For this reason, lower extrusion torque alone does not prove that pigment dispersion has improved. A useful comparison should measure the target defect—such as black-speck count, color strength, or FPV—alongside extrusion load, output, and final-product quality.
Figure 1. Schematic illustration of the dispersion mechanism of a functionalized silicone-based dispersant.
3. Types of Dispersants for Plastics: PE Wax, EBS, Polymeric Hyperdispersants, and Silicone-Based Additives
There is no single best dispersant for every plastic formulation. PE wax, EBS, polymeric hyperdispersants, and silicone-based additives have different functions and should be compared against the actual performance target.
| Dispersant technology | Typical contribution | When it may be considered |
| PE wax | Lubrication and dispersion assistance, particularly in polyolefin systems | A practical baseline when processing and final appearance already meet requirements |
| EBS / fatty-acid derivatives | Lubrication, release, and selected dispersion support | When conventional lubrication and surface behavior are acceptable |
| Polymeric hyperdispersants | Particle-surface affinity and dispersion stabilization | When pigment chemistry requires tailored interaction with particle surfaces |
| Functionalized silicone-based dispersants | Selected combinations of particle interaction, wetting support, and processing lubrication | When dispersion defects persist alongside compounding or processing challenges |
If a current PE wax or EBS package already meets color, processing, and end-product specifications, there may be no reason to replace it. If torque improves but black specks remain, or FPV stays above the required limit, a dispersant with a different balance of particle interaction and lubrication may be worth evaluating.
For a meaningful comparison, test the current formulation against a candidate dispersant using the same raw materials, pigment concentration, let-down ratio, and final-product test conditions wherever possible.
4. Dispersants for Carbon Black Masterbatch and PET Pigment Dispersion
The right pigment dispersant depends on the pigment chemistry and the defect observed in the final product. Carbon black, organic pigments, inorganic pigments, and PET color concentrates can require different approaches.
A masterbatch that looks uniform as pellets may still generate black specks when converted into a thin film. Similarly, a PET pigment formulation may look acceptable before filtration but still produce a high filter pressure value during melt processing. Evaluate dispersion using the downstream test that reflects the customer's actual quality requirement.
Carbon Black Dispersant for LLDPE Agricultural Film Masterbatch
A masterbatch customer reported large and fine black specks during blown-film testing. The concentrate contained 40 wt% carbon black in LLDPE, with a reported LLDPE melt flow rate of approximately 5 g/10 min. The customer used an internal mixer followed by single-screw pelletizing and evaluated the concentrate in agricultural blown film at approximately 10 μm thickness.
The customer had assessed several dispersing or processing additives, including PE wax (10% addition in one trial), EBS, PETS, and products identified as 6100 and 6400. In the customer's qualitative film evaluation, SILIMER 6200 gave the most satisfactory appearance among the options tested.
This is a customer-reported, application-specific comparison; no quantified percentage reduction in black-speck count was provided. Follow-up trials should measure black-speck number and size over a defined film area under consistent let-down and film-processing conditions.
Liquid Dispersant for PET Pigment Dispersion: SILIMER 6600 FPV Evaluation
A separate customer evaluated SILIMER 6600 in a PET formulation containing 3 wt% pigment. The practical target was filter pressure value (FPV), which helps assess how pigment agglomerates affect filtration during melt processing. The customer calculated SILIMER 6600 dosage relative to pigment weight, not the total PET compound weight.
| SILIMER 6600 dosage (based on pigment weight) | Customer-reported FPV |
| 1% | Approximately 7 bar/g |
| 3% | Approximately 3.5 bar/g |
| 5% | Below 1 bar/g |
At 5% of pigment weight, the customer reported an FPV below 1 bar/g, compared with approximately 7 bar/g at 1%. This provides a specific reason to evaluate SILIMER 6600 when filtration performance is the concern; it is not a universal FPV target for other pigments.
The PET evaluation used 3 wt% pigment and is an FPV case study, not a high-loading masterbatch demonstration. It does not establish an increase in achievable pigment concentration.
5. Dispersants for High-Loading Pigment Masterbatches
Increasing pigment concentration changes more than the cost structure of a masterbatch. As solids increase, the carrier resin must wet more particle surface, mixing resistance can rise, and the formulation may become harder to extrude, filter, and dilute into the final resin.
The key question is not simply, "Can more pigment be added?" It is, "Can the target loading be reached while maintaining color development, throughput, and downstream quality?"
Step 1 — Establish Dispersion at the Current Loading
Keep the pigment grade, carrier resin, pigment percentage, and let-down ratio constant. Compare the current additive package with a candidate dispersant for color strength, visible agglomerates, FPV where applicable, torque, melt pressure, throughput, and final appearance. These measurements help distinguish improved particle dispersion from lubrication alone.
Step 2 — Evaluate the Target Higher Loading Separately
Only after the current formulation meets its specifications should a higher-pigment formulation be tested. Recheck dispersion, extrusion stability, downstream dilution, and final-product quality. A successful trial at the original loading does not establish a higher achievable loading limit.
Step 3 — Compare the Cost per Acceptable Finished Product
Assess pigment content, dispersant dosage, output, energy consumption, scrap, and product consistency together. A lower additive cost does not necessarily mean a lower total production cost if the formulation creates more rejects or requires additional processing.
The carbon black and PET examples in Section 4 illustrate two different evaluation targets: downstream film appearance and FPV. Neither result should be interpreted as a universal loading limit or transferred to a different pigment-resin system without testing.
6. Dispersants for Flame-Retardant Compounds: Balance Dispersion, Fire Performance, and Mechanical Properties
Effective distribution of flame-retardant additives is important, but dispersion alone does not determine final compound performance. A dispersant is not a substitute for the flame-retardant package; any formulation change must be evaluated for its effects on both mechanical properties and fire performance.
Different flame-retardant systems present different formulation challenges. Phosphorus–nitrogen (P–N) systems may rely on intumescent char formation, while bromine–antimony (Br–Sb) systems involve different flame-retardant mechanisms. ATH/MDH-filled halogen-free flame-retardant (HFFR) cable compounds face challenges associated with high mineral loading, dispersion, and extrusion.
Dispersants for flame-retardant compounds should therefore be evaluated within each specific formulation. Results from one chemistry should not be generalized to another.
Vertical-Burning Evaluations in Selected Polyolefin Flame-Retardant Systems
In selected polyolefin P–N and Br–Sb formulations, reference formulations and comparative-additive groups were recorded as V-1, while corresponding test formulations containing selected SILIMER dispersants were recorded as V-0 in SILIKE's internal vertical-burning evaluations.
| Flame-retardant system | SILIMER-containing test formulations recorded as V-0 |
| P–N system | 0.2% SILIMER 5500; 0.2% SILIMER 6600; 0.2% SILIMER 6150 |
| Br–Sb system | 0.2% SILIMER 6600; 0.4% SILIMER 6150 |
These classifications apply only to the complete formulations and test conditions evaluated. They do not guarantee the same rating in other resin or flame-retardant systems.
Figure 2. Effect of SILIMER dispersants on vertical-burning performance in selected polyolefin flame-retardant systems.
Figure 3. Char residue morphology and flame-retardant masterbatch microstructure in selected P–N and Br–Sb formulations.
The micrographs provide visual observations of the selected samples. They should be interpreted alongside formulation records and performance tests, not as standalone proof of a specific flame-retardant mechanism or quantified dispersion improvement.
Limiting Oxygen Index (LOI) Comparisons
The following internal comparison results were recorded for selected polyolefin flame-retardant formulations.
Figure 4. Effect of SILIMER dispersants on limiting oxygen index (LOI) in selected polyolefin flame-retardant formulations.
These values are formulation-specific internal results. LOI and vertical-burning classifications measure different aspects of fire behavior and should not be treated as interchangeable results.
Effect of SILIMER 6150 Dispersant on the Mechanical Properties of Flame-Retardant Compounds
In a separate mechanical comparison, the formulation containing 1% SILIMER 6150 recorded 473.31% elongation at break and 13.62 MPa tensile strength, compared with 479.46% and 13.29 MPa, respectively, for the reference formulation. Under these test conditions, elongation remained close to the reference, while measured tensile strength was slightly higher. These measurements apply to the tested formulation and are not universal mechanical-property claims.
Effect of SILIKE Silicone hyperdispersants on the Processing Performance
In suitable formulations, SILIKE SILIMER plastic & composite dispersants may also help reduce melt viscosity, extrusion torque, and melt pressure, supporting processability and extrusion stability.
7. How to Select the Right Dispersant for Your Polymer Formulation
The physical form and incorporation route are important when selecting a dispersant for polymer compounding. A powder additive, pelletized additive, and liquid dispersant may suit different feeding, premixing, and compounding requirements.
| Dispersant option | Physical form | Potential application fit | Starting dosage guidance |
| SILIMER 6150 | Modified silicone wax powder | Selected inorganic pigments, fillers, and flame-retardant powder treatment | 0.5–6%; confirm the application-specific dosage basis |
| SILIMER 6200 | Pellets | Selected PE/PP color concentrates and masterbatch compounding | 1–2.5%; confirm the formulation dosage basis |
| SILIMER 6600 | Liquid modified copolysiloxane | PET pigment dispersion, powder premixing, and compatible polymer systems | For powder dispersion, 0.5–5% of powder weight |
As an initial screening guide, SILIMER 6150 may be considered for selected powder-treatment applications, SILIMER 6200 for pellet-fed color concentrate and masterbatch compounding, and SILIMER 6600 where liquid dosing or powder premixing is suitable. Final selection and dosage should be established through application-specific trials.
For full product information on Dispersants for Color Masterbatches, Pigment Concentrates, and Flame-Retardant Compounds, visit the SILIKE Silicone hyperdispersants product pages for SILIMER 6150, SILIMER 6200, and SILIMER 6600.
8. How to Evaluate a Dispersant Supplier and Application Support
A useful dispersant supplier does more than offer a range of grades. The supplier should help the manufacturer identify a compatible candidate and define how to determine whether it addresses the actual production problem.
For a meaningful trial, agree on acceptance criteria before testing. Criteria should reflect the end product as well as the compounding process.
| Application | Primary acceptance measure | Supporting checks |
| Carbon black masterbatch for blown film | Black-speck number and size per defined film area | Same let-down ratio, film thickness, and processing conditions |
| PET pigment dispersion | FPV under controlled test conditions | Pigment concentration, filter setup, and melt-processing conditions |
| High-loading color concentrate | Color and dispersion quality at target pigment loading | Melt pressure, torque, output, and downstream dilution |
| Flame-retardant compound | Applicable fire-performance and mechanical specifications | Powder distribution, extrusion behavior, and sample conditioning |
To help identify a suitable dispersant for your formulation, share the base polymer and grade, pigment/filler/flame-retardant chemistry, loading level, incorporation method, processing equipment, and the main defect or performance target.
9. Why Work with SILIKE on Dispersant Selection?
At SILIKE, we have developed silicone-based additives for plastics and rubber since our founding in 2004. Our Chengdu-based research and development team works on polymer processing, dispersion, and surface modification. across multiple application areas.
Frequently Asked Questions About Dispersants for Plastics
What is the best dispersant for color masterbatch?
The best choice depends on the pigment, carrier resin, loading level, and processing route. A suitable pigment dispersant should be evaluated for color development, agglomerate reduction, processing stability, and downstream product quality. SILIMER 6200 is one candidate for selected PE/PP color concentrate applications.
Which dispersant is suitable for high-loading pigment masterbatches?
The choice depends on pigment surface characteristics, carrier resin, target loading, and compounding equipment. Compare candidate dispersants at the current loading before increasing pigment concentration, then verify extrusion stability and downstream quality at the target loading.
How can you improve carbon black dispersion in LLDPE masterbatch?
Evaluate powder wetting, mixing energy, carrier-resin compatibility, and the downstream film appearance. In a customer evaluation using 40 wt% carbon black in LLDPE, SILIMER 6200 received the most satisfactory qualitative film-appearance feedback among the additives tested.
What is a suitable dispersant for PET pigment dispersion?
A dispersant compatible with PET processing and the pigment system should be selected based on FPV and final-product requirements. In one customer evaluation with 3 wt% pigment, SILIMER 6600 at 5% of pigment weight achieved a reported FPV below 1 bar/g.
How do silicone-based dispersants differ from PE wax and EBS?
PE wax and EBS are commonly used for lubrication and processing support. Selected silicone-based dispersants may offer a different balance of particle interaction, wetting support, and processing lubrication. The best option depends on the formulation and should be established through comparative trials.
Can dispersants help reduce filter pressure value (FPV)?
A suitable pigment dispersant may help reduce agglomerates that contribute to filtration pressure. FPV comparisons are meaningful only when pigment loading, test equipment, filter setup, and processing conditions are controlled.
Which dispersants are suitable for flame-retardant compounds?
The answer depends on the flame-retardant chemistry, polymer matrix, filler loading, and required fire and mechanical properties. Selected SILIMER grades have been evaluated in specific polyolefin P–N and Br–Sb formulations; results should not be generalized to other systems.
How do you select a dispersant for polymer compounding?
Start with the powder type, polymer, loading level, production route, and the defect to be improved. Compare candidates using application-relevant measures such as black-speck count, color strength, FPV, torque, melt pressure, throughput, mechanical properties, and fire performance.
Looking for a Dispersant for Your Formulation?
If you are developing color masterbatches, high-loading pigment concentrates, or flame-retardant compounds, please share your base polymer (PE, PP, PET, etc.), pigment or filler type, loading level, processing method, and main challenge with SILIKE. Our technical team can recommend a suitable dispersant for your formulation and discuss technical evaluation options.
Email: amy.wang@silike.cn | Website: https://www.siliketech.com/
Technical note: Customer trials and internal comparative results in this article relate to the specified formulations and test conditions. Actual performance must be established in the intended application.
Post time: Nov-11-2026
