分散剂:色粉填料打不开?分散均匀了颜色稳、强度稳

塑料知识科普 发布时间: 2026-09-16 4708 阅读

After a batch of color masterbatch is made, the color is sometimes deep, sometimes light, and the surface even has visible specks. When the customer lays it on a black background, they frown. Nine times out of ten, this isn’t because the pigment was wrong; it’s because it wasn’t properly dispersed. Pigments and fillers are things with particle sizes down to several microns; their surfaces are charged and tend to clump. Just stirring hard with a twin-screw extruder won’t make them uniform. Outsiders don’t understand this; they think if you throw in the pigment and stir, it will even out. But micron-level particles have very high surface charge, and with static they clump into masses. Slight differences in temperature, shear, or residence time, and the dispersion will be uneven. At this point, adding a bit of dispersant—spending a little—can save the whole batch. Besides coloring, fillers and modification also can’t do without dispersants. When you add calcium carbonate, talc, or glass fiber into PP or PE, the more filler you add, the more brittle the material and the rougher the surface. Adding dispersant also breaks up the filler, so that high loading won’t ruin the properties. So dispersants aren’t just for coloring; they’re also for fillers and modification. The more calcium carbonate or talc you add into PP or PE, the more you need to disperse it, otherwise the fillers clump, and the molded parts will have white spots and low strength. So whether you are making masterbatch, colored parts, or doing filler modification, dispersants are an unavoidable part. Today we’re going to thoroughly explain dispersants: what exactly they do, how much is cost-effective, and how to choose them.

Let's first look at a table and lay out the background of the dispersant.

systemRepresentative varietiesKey FeaturesTypical usesAdd ratio
Mineral oilsWhite oil / Paraffin oilQuick wetting, cheap, easy to separate during post-processingPre-dispersion of PE/PP color masterbatch, pigment wetting0.3%–1.5%
Polyolefin waxesPE wax, PP waxGood lubrication, dispersion, and heat resistanceColor masterbatch, filler masterbatch carrier dispersion1%—3%
Fatty acid derivativesStearic acid, EBS, stearateLubricates and demolds simultaneously, requires a small amountPVC/Pigment Dispersion, Internal Lubrication0.2%—1%
Polymer / SuperdispersantPolar grafted/anchored dispersantAnchoring groups capture pigments, disperse and stabilizeDifficult-to-dispense pigments, carbon black, high filling1%—5%
Dispersant MasterbatchCarrier dispersant premix masterbatchEasy to weigh, less dustSmall and medium-sized factories directly add according to proportion2%—6%

Note: The above are common industry systems and addition ranges. Specific grades, addition amounts, and migration resistance should be based on the manufacturer's official TDS.

The color is unstable, and most likely it’s not the fault of the pigment.

Many factories, once they encounter color differences or color spots, their first reaction is to argue with the pigment supplier, saying that your pigment batch is no good. But if you investigate carefully, you'll find that even after switching to three different pigments, the problem still occurs. Why? Because the pigment itself is fine; it just doesn’t stay properly in the plastic. Once pigment particles clump together, you get color spots after injection molding; if the dispersion level fluctuates, the color comes out inconsistently deep and light. Ningbo Kolon New Materials Co., Ltd. has been in the plastics additive industry for many years and has seen this often — color stability depends seventy percent on dispersion, and only thirty percent on the pigment itself. Once you get dispersion right, expensive pigments are worth the price; if dispersion fails, even the most costly pigments are wasted. This is not an exaggeration. Think about it: in a ton of colorant, pigments may only account for a few percent, but it costs quite a bit; yet if that small percentage of pigment isn't dispersed, you get clumps of black in some areas and no color in others, leaving the finished parts looking blotchy. Customers check the uniformity across the whole batch, not how expensive your pigment is. The step of dispersion is what actually makes the money spent on pigments useful; if dispersion is inadequate, that money is just wasted.

Figure 1 Dispersion process of color powder and plastic granules

A dispersant is the mediator between the pigment and the resin.

Think of this more simply. The surface of pigment particles likes pigment, while the plastic melt likes oil. Each sticks to its own kind, and when you mix them together, they clump up. Dispersant molecules have a polar end that hooks onto the pigment surface and a long carbon chain on the other end that loves the plastic melt. When it attaches to the pigment particle, it's like putting a 'lubricant coat' on each particle, making it less likely for the particles to stick together. When extruded through a twin-screw, they naturally disperse. In plain language: the dispersant is a mediator between pigment and resin, holding on to both sides so the material mixes evenly. You can think of it as assigning each pigment particle a middleman; the particles can no longer stick together, and once extruded through the twin-screw, they go their separate ways and never clump again.

There’s another benefit: when dispersed, not only does the color remain stable, but the pigment and filler are evenly distributed, reducing stress concentration points. This improves the impact resistance and strength of the product; the melt flows more smoothly, processing torque decreases slightly, and mold temperature and pressure look good. Don’t underestimate that one or two percent addition—it affects everything. Let’s go into more detail about the characteristics of several dispersants: mineral oil is cheap and wets quickly, but has poor heat resistance; using too much can cause oil to appear on the product surface, so it’s suitable for pre-mixing wetting. PE wax has good heat resistance and balances lubrication and dispersion, commonly used in masterbatches and filling masterbatches. Stearic acid and EBS types provide lubrication and demolding assistance, effective even in small amounts. When dealing with carbon black or hard-to-disperse organic pigments, you need a high-molecular dispersant, which has anchoring groups that firmly grab the pigment. Choosing a dispersant doesn’t mean the more expensive, the better; it has to be compatible with your pigment and base material. Another common pitfall: too little dispersant is ineffective, but too much is also bad. Excess can make the product surface sticky, lead to precipitation, affect printing and secondary processing, and may even reduce mechanical properties. Therefore, follow trial production: start with small tests to find the precise amount that just disperses the color particles. Whether the dispersant is selected correctly also depends on its compatibility with other additives. It is often used together with lubricants and coupling agents: the coupling agent bonds fillers and resin, while the dispersant breaks up fillers and pigments. They do not conflict and can even support each other. But if you choose a dispersant that clashes with the coupling agent, or one that precipitates severely, surface treatment and printing issues will follow. So the formulation is an integrated system—you shouldn’t just add things in isolation.

Adding one or two pieces of material saves the entire batch of returns

Let's first talk about why manufacturers are willing to buy dispersants. For factories making color masterbatches or colored products, there are two things they fear the most: first, returns due to color differences—if a batch is off-color, the entire pallet might be sent back, and the cost of the materials, shipping, and labor would all have to be compensated; second, when there is high filling, the material can become brittle, the surface rough, and the strength collapses. These two types of losses can easily amount to tens of thousands of yuan. The amount of dispersant added is only about 1-2%, so for a ton of material, it only costs a few hundred yuan more. Spending a few hundred yuan to plug a potential return loss of tens of thousands is a bargain no matter how you look at it. This is a small investment leveraged to manage a large account—it's a small quantity, but it determines the lower limit of appearance and yield. This is even more evident in the color masterbatch industry: in a ton of color masterbatch, dispersant might only account for 2-3%, but it determines whether this batch will mix evenly into plastic and whether there will be color specks. If a color masterbatch factory does a poor job dispersing, downstream customers will encounter problems when blowing film or molding, and repeat customers will disappear. So don’t skimp on dispersants. Anyone with experience in this industry understands that the major costs for colored products are not the little additives, but the rework, downtime, and returns after something goes wrong. Ningbo Cologne New Materials Co., Ltd. often calculates this for clients: if an order is returned once due to a color difference, the loss is enough to buy several years’ worth of dispersants. So don’t skimp on additives; add what’s necessary to secure the yield of the entire batch, and that’s real savings.

If we lay out the added amount and the total return, it is like this:

ProjectDo not add / add less dispersantAdd dispersant according to the recommended amountDifference
Pigment wettingProne to clumping, many specksWell moistened, few color spotsThe appearance yield has improved
Color stabilityLarge batch color differenceBatch consistencyReturn rate decrease
Melt flowHigh torque, difficult to machineLiquidity improvementProcessing saves electricity and effort
Product strengthStress concentration, brittlenessEvenly dispersed, consistent intensityMechanical properties retention
Comprehensive costHigh returns and defective productsThe additives cost several hundred yuanSave much more than spend

Let's talk about an unavoidable calculation: should you buy pre-mixed masterbatch/modified colorants, or mix it yourself using base materials and dispersants? There is no standard answer; it depends on whether your quantities are large or small, how often you change colors, and whether you have color-matching capability. There’s a calculation that needs to be clear here (industry standard, 2026 market reference, subject to current market prices): buying modified colorants directly includes the manufacturer’s processing fee, packaging, administrative and sales expenses, plus a 10-20% profit margin; mixing it yourself with base materials and dispersants is equivalent to saving those added costs. The raw material cost accounts for 70-85% of the tonnage cost of modified colorants, and what you save is exactly that remaining portion—the larger the quantity, the more you save. Comparing the two makes it clear:

Comparison itemDirectly buy colored/modified materialsBase material dispersant self-modifiedSuitable for whom
material costIncluding processing fee, additional charge by brandBase material with a small amount of dispersant even lowerLarge dosage, fixed formula
FlexibilityCan only choose from pre-made shadesColor/scale adjustable at any timeMultiple varieties, small batches
Minimum order lead timeFull ton orders only, long delivery timeAdd the additive as neededRush order, trial production
Process controlConstrained Supplier BatchYou have control over your own machine.Has color matching and detection capabilities
Boundary ReminderConvenient and worry-freeRequires color matching and proofing capabilityIf the quantity is too small or the color is very strict, buying color masterbatch is more economical.

Any kind of plastic can be used; the key is to look at the dispersion target.

Dispersants are not patented for any specific type of plastic; as long as you add pigments or fillers to the material, they can assist. Different plastics have very different melting points, polarities, and applications, so the dispersion system must be adjusted accordingly: for making films, you need to consider smooth extrusion; for transparent parts, choose ones that don't affect haze; for spinning, they shouldn't clog the filter; for high filler content, flowability must also be considered. The following cross-category matrix lists how they are commonly used in various plastics.

Plastic productsTypical scenarioAddition rangeEffectPrecautions
PP PolypropyleneColored parts, appliance housings0.5%—2%Stable color, bright surfaceChoose heat-resistant type to prevent precipitation
PE PolyethyleneFilm, packaging coloring0.3%—1.5%Spread out well, does not affect openingThe film takes note of smoothness
ABSAppliance shells, toy coloring1%—3%Few color spots, even glossHeat resistance cannot be low
PS/HIPSStationery, sheet coloring0.5%—2%Consistent colorPay attention to the effect of transparency
PA NylonEngineering part coloring1%—3%Few spotsHydrolysis-resistant, heat-resistant
PCColoring of transparent parts0.3%—1%Low hazeDon't choose one that affects transparency
PVCColoring of profiles and pipes0.5%—2%Disperse LubricationCompatible with a stable system
PETSheet and fiber coloring0.5%—2%Spinning does not clog the filter screenHeat-resistant, low volatility
Color masterbatch carrierProduction of various color masterbatches2%—6%Pigments are easily dispersedCompatible with the carrier

Doing different categories results in very different dispersion requirements: adding carbon black requires a super-dispersant, adding regular titanium dioxide only needs PE wax, and adding hard-to-disperse organic pigments requires an anchoring type. Ningbo Kolon New Material Co., Ltd. regularly stocks white oil, PE wax, EBS, and polymeric super-dispersants. For factories making color masterbatches and colored parts, send the types of plastics, pigments, and target colors, and Kolon New Material will help you with the dispersion system, calculate the addition amount, and can also provide sample trials. For film applications, ask about smooth extrusion; for transparent parts, ask about haze; for high filler applications, ask about flow. Kolon New Material formulates according to your actual conditions, not using a single general material for all parts.

Tried three batches of pigment but it didn’t work; the problem was not adding these two grams.

The following scene is not uncommon in factories that handle color parts (customer information has been anonymized). A factory around Ningbo that makes PP appliance housings had an order for light gray a couple of years ago. The color kept being unstable—one batch darker, one batch lighter, with color spots on the surface. The factory believed the pigments were to blame and consecutively switched three pigment suppliers, spending a lot of money, but the problem didn’t decrease at all. The client had already warned that if there were more issues, they would switch factories. The factory owner was extremely anxious at that time, tried changing pigments and adjusting the pigment amount, but the color was still inconsistent. Increasing the pigment amount meant higher costs and wasn’t a long-term solution.

Later, this factory approached Ningbo Kolon New Materials Co., Ltd. Kolon New Materials examined their materials and process and found that the problem was not with the pigments themselves, but with dispersion — the formula relied solely on hard mixing with a twin-screw extruder, without adding a wetting dispersant, so the pigment particles clumped together, naturally causing many color spots and uneven color. The next step was straightforward: they added PE wax and high-molecular dispersants according to the pigment type, first making small batch samples, testing color spots against a black background, and measuring color difference; once stable, they proceeded to large-scale production. After the adjustment, the color spots basically disappeared, the batch-to-batch color difference was reduced to within the customer's acceptance range, and the color of this batch was consistent with the next. The steps that originally required workers to monitor the color and adjust the machine to correct it were also eliminated, making the production process smoother. The factory owner did the math: the dispersant costs only a few hundred yuan per ton of material, but previously the money wasted on returns and pigment replacements due to color differences was several times that amount. Even better, since the color became stable, the customers' trust in the factory returned, and the following orders for the same models went smoothly, with delivery times and quantities no longer subject to supplier whims, giving the factory much more confidence.

(Note: The scenario is summarized based on common industry color-matching issues, not an actual transaction record.)

Clearly explain the dispersed objects so that the dispersant can be added accurately.

Below is a table summarizing common situations and recommended approaches for you to reference as needed. One more reminder before placing an order: Don't just look at the price of dispersants; you need to ask whether they are resistant to migration, compatible with your base material, and whether they have been tested for color points. Also, if used in products that come into contact with food, compliance must be confirmed separately; for outdoor items, you need to check whether the dispersant itself is weather-resistant. If these questions are not clarified, buying cheap materials that end up unusable is still a waste.

situationRecommended approachPrecautions
Ordinary Titanium Dioxide/Inorganic PigmentPE wax, a small amount of white oilEven enough, low cost
Carbon black/difficult-to-dispense organic colorPolymer superdispersantThe anchoring group must be correct
High-filling masterbatchPE Wax Dispersant CompoundBalance mobility and dispersion
Transparent/Light-colored partsLow-impact dispersantDon't let the fog density go up
Film/SpinningHeat-resistant and low-volatility typeAnti-clogging net, anti-precipitation

Before blaming the pigment for color stability, ask yourself whether the dispersant has been added properly.

If the dispersant is added accurately, both the color and intensity remain stable.

Statement: The brands and trademarks mentioned in this article are owned by their respective original manufacturers. This article is a third-party material selection knowledge sharing, and the specific grades, parameters, prices, certifications, and other information involved in the text are subject to the latest official information from each manufacturer. This article does not constitute any procurement or investment advice.

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