2. Why Is Choosing a Black Masterbatch More Complex Than It Seems?
3. Carbon Black Content: Is Higher Always Better?
1. What Does a High Carbon Black Content Mean?
4. What Are the Advantages of a High Carbon Black Content?
5. Why Does "High Carbon Black Content" Not Equal "High Quality"?
6. The Type of Carbon Black Matters Too
7. One of the Most Important Indicators for Black Masterbatch: Dispersion
8. Why Does Carbon Black Disperse Poorly?
9. What Is FPV? Why Is It Often Tested for Black Masterbatch?
10. Why Can Two FPV Values Not Be Compared Directly?
11. Carrier Resin: Why Does It Matter?
12. Processing Temperature Is Also an Important Factor in Black Masterbatch Selection
13. Let-Down Ratio: How Much Black Masterbatch Should Be Added?
14. How Should the Cost of Black Masterbatch Be Calculated?
15. How to Choose Black Masterbatch for Different Applications?
16. Why Must Mechanical Properties Also Be Tested?
17. How to Actually Test a New Black Masterbatch?
18. The 7 Most Common Mistakes When Purchasing Black Masterbatch
19. How to Inquire with a Supplier to Get the Right Solution Faster?
20. How to Judge Whether a Black Masterbatch Supplier Is Truly Professional?
FAQ: Common Questions About Black Masterbatch
Conclusion: What You Should Really Compare Is Not "How Much Carbon Black," but the Final Result
Guide to Selecting Black Masterbatches: Carbon Black Percentage, Dispersion and Applications
Typically, when people talk about black masterbatch they ask the same question in the very beginning: "What is the percentage of your carbon black?"
20%, 30%, 35%, 40%... Seems like it should be easy to evaluate and compare.
But those, who had some experience in working with films, injection molding, pipes, fibers or engineering plastics know that this is not the case. More carbon black in the formula doesn't mean more efficient black masterbatch. And the lower price doesn't necessarily mean lower total coloring costs.
For example, there can be two masterbatches with the same carbon black percentage 30%. First one can hit the mark at an addition level of 2%. While the second one requires 3% or even more. Some masterbatches produce no black particles during the production process. Other masterbatches tend to cause higher filter pressure, color streaking, gelling or poor dispersion.
Thus, when selecting a Black Masterbatch, you should not base your selection on one single parameter – "carbon black percentage". You should compare the set of parameters:
Carbon black grade + formula system + dispersion ability + carrier compatibility + addition percentage + processing performance + end product performance + total cost.
The following article will focus on carbon black content, black masterbatch dispersion, FPV, carrier resin, let down ratio, and selection method. It is approached from both the buyer’s perspective and from the production perspective. It will assist you to make a decision whether the black masterbatch suits your production process. The following article will focus on carbon black content, black masterbatch dispersion, FPV, carrier resin, let down ratio, and selection method. It is approached from both the buyer’s perspective and from the production perspective. It will assist you to make a decision whether the black masterbatch suits your production process.
Black masterbatch is a kind of plastic colorant. In this case, carbon black acts as the primary coloring agent. Carbon black is premixed and prepared under high concentration with a carrier resin, dispersant, and other functional additives.
To put it simply, black masterbatch does not only mean "pelletizing of carbon black". It helps carbon black, which is hard to introduce in a homogeneous manner into a plastic matrix, to get into the final resin in a more stable and cleaner form.
Generally speaking, the composition of a typical black masterbatch includes the following:
Carbon Black
Carrier Resin
Dispersant / Wetting Agent
Processing Additives
UV stabilizer, antioxidant, or other functional additives depending on the application requirements
Thus, the ultimate performance of Black Masterbatch depends on many different factors.
There is one thing that should be especially highlighted. A black masterbatch is not a simple product in which "more is better".
If you strive to increase the content of the product disregarding dispersion, flow, and processability, the final product might become more difficult to manufacture.
Black appears to be one of the easiest colors visually. From the technological side, however, black masterbatch is frequently one of the most challenging materials to produce.
The explanation for this situation lies in the very fine particle size of the carbon black. At the same time, carbon black has a strong tendency to agglomerate.
If these agglomerates cannot be completely dispersed during the manufacturing of the masterbatch, then such problems can be expected when using it in customers' processes:
Black specks
Color streaks
Color inconsistency
Surface non-uniformity
Increasing filter pressure
Filter blockage
Gel formation or weak points in film
Broken fibers
Molding surface defects
Unstable color from batch to batch
So, what really should be asked here is:
Does the carbon black in this black masterbatch have stable dispersion under my resin and process conditions?
This is much more relevant than carbon black content alone.
This is one of the most frequently asked questions in the process of buying black masterbatch.
The Black Masterbatch available on the market can contain 20%, 25%, 30%, 35%, 40%, and even more carbon black.
At first glance, 40% is certainly better than 30%.
But the truth is that you should not judge it like this.
Carbon black concentration gives the information about the carbon black concentration in the black masterbatch per kilogram.
For instance:
The first black masterbatch has 40% carbon black concentration and 2% addition rate.
The theoretical final carbon black concentration is around:
40% x 2% = 0.8%
The second masterbatch has 20% carbon black concentration and 4% addition rate:
20% x 4% = 0.8%
Thus, the theoretical amount of carbon black used is equal in both cases.
So, "40% vs 20%" is not enough to determine which one is better.
Nevertheless, there is no doubt that High Concentration Black Masterbatch has its own advantages.
Firstly, it will allow reducing the addition ratio.
Provided the masterbatch possesses sufficient tinting power and good dispersion, the client can achieve the targeted blackness in a low addition ratio.
Secondly, it will reduce the consumption of the additional resin.
In case the client wishes to reduce the influence of additional resin on the final resin system, a high concentration masterbatch may be preferable.
Thirdly, transportation and storage become more concentrated.
In achieving the same coloring effect, the theoretical consumption of the masterbatch will become less.
There is only one condition for these advantages:
The masterbatch should preserve the dispersion properties after achieving high concentration.
If the 40% carbon black masterbatch is worse dispersed than the 30%, the advantage of a lower addition ratio can be leveled off by the problems in the manufacturing process.
With the increasing carbon black loading rate, the complexity of the formulation design increases as well.
The spacing among carbon black particles decreases continuously. System viscosity and dispersion ability may become higher.
If:
The dispersing system is not properly designed
The wettability of the carrier is insufficient
The mixing intensity is low
The screw design is inappropriate
The process temperature is not suitable
The carbon black is difficult to disperse
The result will be a high-concentration masterbatch containing many agglomerates.
Thus, what the high-quality high-concentration Black Masterbatch really checks is how to maintain proper carbon black dispersion under the condition of increasing carbon black loading rate.
This is also the point where different suppliers could distinguish themselves easily.
All kinds of carbon black do not possess the same properties.
Some carbon blacks can be different in the following aspects:
Particle Size
Surface Area
Structure
Tinting Strength
Jetness
Undertone
Dispersion
Electrical Properties
Among those mentioned above, there are some characteristics which can influence the tinting strength and dispersion difficulty such as particle size and surface area.
Typically, the finer carbon black can provide higher tinting strength and jetness but its dispersion difficulty can increase at the same time.
Thus, the formulation engineer should find a compromise between the following two options:
High enough tinting strength + Dispersion difficulty under control.
This balance can vary depending on the application; thus, it may be different in case of common black injection molding products compared to the high-quality films, fibers or engineering plastics.
Of all the items one could focus on, I would say it’s essential for the buyers to pay attention to:
Black Masterbatch Dispersion。
Disperse refers to the distribution of the carbon black in the polymer.
Carbon black disperse is good when there are fewer carbon black agglomerations. It will allow it to disperse in the resin better.
In practice, it might influence:
Number of black spots
Color streaking
Surface evenness
Gloss
Color difference
Filter pressure
Film defect
Fiber breakage
Final mechanical properties
Especially regarding films and fibers.
An agglomeration of carbon black in the thick-walled black masterbatch may not be visible. However, in the case of the film of only dozens of microns thickness, the same problem will result in the formation of a defect.
Thus:
The thinner, the faster and the higher requirement of the application, the higher demand for disperse is.
Bad dispersion of Poor Black Masterbatch does not result from one single reason.
1. Poor dispersion ability of carbon black
Some carbon black with a strong tinting strength is more prone to agglomeration and requires better wetting and dispersion systems.
2. Improper dispersant selection
Proper dispersant should achieve a reasonable interaction between the carbon black and the carrier resin.
"Addition of dispersant" does not necessarily ensure good dispersion.
3. Unsuitable carrier resin
When the carrier resin cannot be compatible enough with the customer’s base resin, the final dispersion will also be unsatisfactory.
4. Low energy input during the mixing
Factors such as screw configuration, shear rate, speed, and residence time determine the destruction of the carbon black agglomerates.
5. High carbon black loading
High carbon black loading will further complicate the formulation and manufacturing process.
So, dispersion of Poor Black Masterbatch is essentially an issue determined collectively by formulation, equipment, and process factors.
For products such as films and fibers that require high dispersion characteristics, FPV (Filter Pressure Value) serves as a highly valuable reference indicator.
In essence, FPV evaluates the effect of difficult to disperse particles and agglomerates of the masterbatch on the filter pressure through a filter unit.
As expected, under normal circumstances, a smaller value of FPV generally results in good filtration behavior and fewer agglomerates.
However, there exists a highly popular purchase misconception regarding FPV:
Values of FPV obtained through various testing conditions are not always comparable.
For example, if Supplier A states that:
FPV = 1.5 bar
And Supplier B states that:
FPV = 3 bar
Clearly, A is much better.
However, if Suppliers A and B tested using different conditions, this judgment might be misleading.
When comparing FPVs, one should check at least the following:
Test resin
Test temperature
Masterbatch blending rate
Filter Mesh
Filter Layer
Testing Time
Output
Testing equipment
If it tests the concentrated masterbatch or the diluted system.
In particular, for the black masterbatch, varying concentrations and test conditions might really influence the outcome.
Therefore, the correct procedure would be to:
Unify the test conditions, then compare FPV.
While many customers consider only the carbon black and ignore the Carrier Resin,
in reality, the carrier resin is the crucial matrix that takes the black masterbatch to the customer's manufacturing process.
Popular carrier systems are:
| Customer Base Resin | Common Carrier Direction |
|---|---|
| PE | PE, LDPE, LLDPE and compatible polyolefin systems |
| PP | PP-based carrier |
| PA | PA-compatible carrier |
| ABS | ABS or compatible styrene systems |
| PC | PC-compatible system |
| PET | PET-compatible system |
| TPU | TPU-compatible carrier |
| TPE/TPEE | Selected based on the specific system |
One aspect that must be stressed here is the following:
Carrier Resin is more than just "the same resin is always best."
The specific choice must take into account the following factors:
Base resin grade
Melt index/viscosity
Processing temperature
Transparency
Mechanical characteristics
Application
Ratio
Therefore, when buying a black masterbatch, you must ask not only:
"What is your carrier?"
But also why this specific carrier is the best one for my specific resin and process?"
Temperatures of processing for various plastics are quite different.
For instance:
PE and PP are in the group of relatively common polyolefin processing systems.
ABS, PA, PC, and PET may be characterized by high temperatures of processing.
If the thermal stability of the black masterbatch is inadequate, the following will take place:
Color changes
Color differences
Degradation of additives
Volatiles
Depositions
Smell
Surface defects
Loss of performance properties
That is why, when dealing with engineering plastics such as PA, PC, and PET, an ordinary PE/PP black masterbatch cannot be used.
High-temperature processing processes should be taken into account as a complex one concerning the carrier, carbon black, and additives.
Let-Down Ratio (LDR) is a term that is frequently used in purchasing and manufacturing.
Such examples are as follows:
1:20 ≈ 4.8%
1:25 ≈ 3.85%
1:50 ≈ 1.96%
1:100 ≈ 0.99%
But remember that there might be differences in how different suppliers state the LDR.
This is why when you buy, it is better to ask:
What is the Recommended Addition Rate?
Do not just determine it yourself from "1:50."
This is a fact that consumers tend to ignore often.
Assuming:
Supplier A
Cost per kg: $4/kg
Amount recommended: 2%
Supplier B
Cost per kg: $3/kg
Amount recommended: 4%
At first glance, one might think that supplier B would be more appropriate because it costs a dollar less than supplier A.
However, calculating the cost based on the weight of each ton of output, we see that:
A： $4 * 20kg = $80 per ton of output
B： $3 * 40kg = $120 per ton of output
Therefore, B is actually costlier.
Hence, when buying black masterbatch, what one ought to consider is:
Cost Per Ton of Output of Masterbatch
Instead of just its cost per kg.
There is generally a comparatively higher demand for good black master batch dispersion in the film.
Common applications:
Packaging Film
Agricultural Film
Garbage Bags
Industrial Film
Protective Film
Geomembrane
FIBC
Main concerns:
High dispersion, less black specks, less FPV, consistent extrusion, color difference control, and surface quality.
In case of films, even slight agglomeration forms visible defects.
Injection Molded Black Parts consist of:
Appliance enclosures
Domestic goods
Industrial goods
Electrical and electronic parts
Other than color, the other aspects for injection molding include:
Surface finish
Flow
Impact resistance
Tensile resistance
Heat resistance
Consistency
For highly aesthetic products, dispersion is of utmost importance.
Uses of Black Masterbatch include:
HDPE Pipes
PE Water Pipes
Irrigation Pipes
Drainage Pipes
Cable Ducts
Industrial Pipes
Apart from being black, other outdoor PE pipes are typically concerned about the following:
UV Protection
Weather Resistance
Carbon Black Dispersion
Long-Term Color Stability
It is to be noted here that just by being black is not sufficient for "long-term weather resistance." It all depends upon the carbon black grade, percentage, dispersion, and formulation system as a whole.
Fiber usually needs more sensitivity to masterbatch specifications than usual injection molding.
Important focus areas are:
Good dispersion
Filtration
Melt stability
Viscosity
Gels
Color stability
Spinning stability
If the black masterbatch does well in injection molding, it doesn’t always mean that it will work well in high-speed spinning.
These materials require higher temperatures and greater performance from the material.
As far as PA Black Masterbatch is concerned, one must investigate whether the black masterbatch impacts:
Melt Viscosity
Tensile Strength
Elongation at Break
Fiber Spinning
Injection Molding
Thermal Stability
In these experiments, you cannot only rely on the ultimate appearance.
Even though the blackness requirement is satisfied, if there is a drop in the elongation at break or any mechanical property, the black masterbatch is not considered successful.
Finally, the Black Masterbatch is going to go into the customer’s resin system.
Then, it not only influences its color. But also it may have effects on the rheology and mechanical properties of the final composition.
In particular, for high-performance products, one needs to pay attention to:
Tensile strength
Elongation
Impact resistance
Flexibility
Stiffness
Melt index
Fiber strength
Take PA6 Black Masterbatch as an example. In case the dispersion system, carrier and additive are not selected properly, it may lead to changes in the mechanical properties of the final product.
That is why professional testing must not only include the question:
“Is it black enough?”
But also “After being added, did the mechanical properties of the original resin remain?”
If you are going to change your supplier, you should not only take one sample and compare colors.
The testing can be done by following these steps:
Step 1: Color
Tests:
Blackness
Undertone
Gloss
ΔE
Surface Uniformity
Step 2: Dispersion
Tests:
Dispersion
Black Spots
Streaks
FPV
Filter Pressure
Step 3: Processing Stability
Observations:
Melt Pressure
Extrusion Stability
Filter Pressure
Surface Appearance
Deposits
Step 4: Mechanical Properties
Tests according to the product type:
Tensile Strength
Elongation At Break
Impact Strength
Flexibility
Step 5: Actual Production Test
Then, the actual production test should be done.
Since there might be some significant differences between the lab test and the mass production.
The scale of equipment, manual mixing, feeding stability, screw design and residence time can all be factors that can influence the final test result.
Mistake 1: The higher the carbon black concentration, the better
Wrong.
It only works if you have proper dispersion and process stability.
Mistake 2: The cheaper the black masterbatch, the better the deal
Wrong.
You should determine the real coloring cost per ton of finished goods.
Mistake 3: Pay attention to the FPV index alone
Wrong.
You have to make sure that the test conditions are fully provided.
Mistake 4: Any masterbatch for film, injection, fiber, pipe is universally applicable
Wrong.
Requirements for Film, Injection, Fiber, Pipe, PA, ABS, and other processes can be completely different.
Mistake 5: Consider only color
Wrong.
Dispersion, mechanical characteristics, and processability should also be checked.
Mistake 6: Passed lab tests mean no issues will occur in mass production
Not necessarily.
The reality of the process is much more complicated than the lab.
Mistake 7: Tell your supplier only "I need black masterbatch"
That is too vague.
At least you should provide the resin, its grade, processing technology, processing temperature, wall thickness, desired blackness, and dosage.
In case of sending only one line:
We require black masterbatch for PE.
It is hard for the supplier to give any constructive advice.
The better way to ask the question will be:
1. Base Resin: PE / PP / PA / ABS / PC, etc.
2. Resin Grade: specific grade
3. Processing Method: Film / Injection / Pipe / Fiber, etc.
4. Processing Temperature: processing temperature
5. Product Thickness: product thickness
6. Required Color: blackness, undertone, or sample
7. Suggested Additive Rate: current additive rate
8. Required Properties: UV, weather resistance, mechanical, electrical, etc.
9. Current Problem: black spots, dispersion, color difference, cost, or process stability
The more information you have, the easier it will be for the supplier to come up with a solution to your problem.
You can evaluate based on the following criteria.
Not just informing you about the carbon black percentage
But being able to provide reasons:
Why that specific carbon black has been selected.
Not just providing the FPV to you
But being able to provide reasons:
At which temperature the FPV has been carried out.
Not just informing you about the price
But being able to inform you:
About the addition rate and the final price per ton of product.
Not just providing the TDS to you
But being able to correlate:
Resin + Process + Temperature + Application
And providing practical suggestions.
A true Black Masterbatch supplier should not just finish the quotation process but should be involved in the customer application testings as well.
1. What is the proper carbon black content for Black Masterbatch?
No definite answer is available. Carbon black content could range from 20% to 45%, even more. The proper content would depend on blackness, dispersion, addition ratio, processing facility, and application.
2. Is the high carbon black content always better for black masterbatch?
Maybe not. A high carbon black content will reduce the theoretical addition ratio, but meanwhile, it would also increase the dispersion and processing difficulties. Ultimately, the comparison will be on blackness, dispersion, processing and price.
3. How much Black Masterbatch is usually added?
That largely depends on your application. A lot of plastic applications might be 1% to 5%, but that is definitely not the optimal addition ratio for film, injection molding, fiber, pipe, engineering plastics, etc.
4. Does lower FPV mean better?
Yes, under the same testing conditions. Lower FPV means better filtration performance. However, it cannot be compared independently of conditions such as temperature, resin type, filter mesh, addition ratio, etc.
5. Why do masterbatches having the same 30% carbon black differ from each other?
Because carbon black percentage is just one of the parameters. The quality of carbon black, size, dispersant, Carrier Resin, manufacturing and processing technologies are all critical.
6. Can PE and PP both use the same Black Masterbatch?
Some universal systems are available. However, you should not generalize and suppose that all black masterbatches for PE and PP are interchangeable. Compatibility with base resin must be considered.
7. How to estimate the price of two black masterbatches?
Do not compare prices per kg. It is suggested to calculate costs for one ton of product using "masterbatch price x actual usage level."
8. Why is an actual production test required for black masterbatch?
Because laboratory tests cannot fully emulate client's screw, feeding, temperature, residence time, and manufacturing speed. Only actual production tests can prove stability.
9. What should be paid special attention to in the case of PA Black Masterbatch?
The processing temperatures required for PA are higher. On the other hand, PA is very sensitive to viscosity, dispersion, and mechanical properties. Thus, you should check thermal stability, dispersion, melt viscosity, and mechanical properties altogether.
10. What should you ask a supplier most while choosing Black Masterbatch?
You should ask about the following things at least: the amount of carbon black, the grade of carbon black, carrier resin, dispersion, test conditions for FPV, addition rate recommendation, processing temperature, and experience with applications.
Choosing the right Black Masterbatch depends greatly on the amount of carbon black. Nevertheless, it certainly isn’t everything.
The ideal black masterbatch should find a balance between the following factors:
Quality of Carbon Black
Dispersion
Carrier Compatibility
Thermal Stability
Processing Stability
Blackness Consistency
Mechanical Properties
Price Per Ton
In case your product is nothing more than a regular black injection molded component, then blackness, dispersion, and price will be your priorities.
However, if your products require high standards like films, fibers, HDPE piping, automotive components, engineering plastics PA, etc., then the mere comparison of "30% or 40% carbon black" won't do at all.
A more logical option would be to leave the choice of Black Masterbatch to the supplier, based on your base resin, resin grade, processing method, processing temperature, thickness of the product, and required blackness.
For the simple reason that the true value of something does not lie in an aesthetically pleasing parameter from the laboratory. What really matters is:
Consistently producing products that satisfy your requirements on your production line, at an acceptable cost per ton of product.
When comparing different black masterbatch manufacturers, you should not only ask for their TDS. Instead, you should ask them to present the recommended addition ratio, dispersion, the conditions for the FPV test, and application tips. Afterward, you can make a comparison through testing under the same conditions. This way, you can get results closer to the actual production.
If you require Black Masterbatch for PE, PP, PA, ABS, PC, PET, or any other resin systems, you can contact us. You can provide us with your resin grade, processing method, processing temperature, and intended addition ratio. Then, we can evaluate your application conditions to know the suitable carbon black loading, carrier, and let down ratio.
