What Is an Additive Masterbatch, and How Is It Combined with Color?

The blown film plant was supplying blue rolls to a converter that prints and seals bags on its own lines. The rolls began to stick between layers and the film ran with difficulty on the customer's machine, so the supervisor added a slip and antiblock concentrate to the hopper alongside the blue masterbatch, at a high percentage to ensure the result. The film ran perfectly on the line. A week later, on the converter's printing press, the ink came off with a fingernail and the bag seals opened with little force. The slip agent had migrated to the surface in excess, adding to the slip already present in the resin grade, and formed a layer that prevented ink adhesion and sealing. The converter rejected the entire order and the plant absorbed the cost of the replacement.

An additive masterbatch concentrates a processing, appearance or service-life function and is dosed at low percentages. It is combined with color through parallel dosing or in a single concentrate, with the dose and compatibility validated.

The film that ran perfectly on the line and failed on the printing press

An additive masterbatch, also called a functional concentrate, carries an additive at high concentration within a carrier resin, in pellet form. It is dosed over the resin like any other masterbatch and delivers a function in the part: making the film run, making the part withstand the sun, controlling moisture in the material or making the product traceable. In our article on masterbatch families, we placed it alongside color, white and black.

Small doses with large effects

Most additives act in very small amounts, on the order of tenths of a percent in the part or less. Distributing that amount of powder across several tons of resin so that it reaches every part equally is difficult on the plant floor. The concentrate solves the distribution: the additive is already dispersed in the carrier and is dosed at a percentage the feeder handles with precision.

The counterpart is that a dosing error weighs heavily: one extra percentage point in the feeder can double the additive that reaches the part, and the excess brings its own defects.

Processing, appearance and service life: what the resin alone leaves unresolved

Processing additives: slip, antiblock and desiccant

Slip agents lower the coefficient of friction of the surface so that the film runs on packaging machines. They work by migration: their molecules have low compatibility with the polymer, move toward the surface in the hours and days after extrusion and form a lubricating layer. Antiblock works differently. Its fine mineral particles create a microscopic roughness that prevents two layers from adhering when wound or stacked. Desiccants absorb moisture from the material during processing and reduce surface defects, a useful resource with recycled resins that arrive wet.

Service-life additives: ultraviolet protection, antibacterial and biocide

Ultraviolet protection slows the degradation of the polymer caused by solar radiation. Absorbers convert that radiation into heat that is harmless to the material, and HALS-type stabilizers capture the radicals that initiate degradation. Antibacterial additives reduce the proliferation of bacteria on the plastic surface; our Antibacterial AG works with broad-spectrum nanoparticles and complies with JIS Z 2801 and ISO 22196. Biocides and repellents protect the polymer in applications with microbiological requirements, and the oxo-biodegradable additive Delta Bio accelerates the breakdown of the polymer in stages down to compostable residues.

Identity additives: UV markers and fragrance

UV markers are invisible to the naked eye and are used to authenticate and trace finished products under an ultraviolet lamp. MB Aroma incorporates a fragrance into the plastic and reduces the odors left by reprocessing recycled material. In all three groups, the function depends on the additive reaching the part in the correct amount and coexisting with everything else in the formulation.

Migration and competition for the surface: the risk of stacking additives

Migrating additives and downstream processes

Slip, antistatic and antifog agents perform their function at the surface and reach it by migration. The amount that migrates depends on the dose, the storage temperature and the time elapsed since extrusion. That is why the film leaves the machine with one level of performance and reaches another days later, already at the customer's plant. An excessive surface layer affects corona treatment, ink adhesion, lamination and sealing. The dose of a migrating additive is defined with the next process in mind.

The resin also counts. Many polyethylene film grades leave the producer with slip and antiblock already incorporated. Adding a concentrate without checking the resin's technical data sheet doubles the additive, which is what happened with the blue rolls.

Additives that compete with each other

Two additives that seek the surface can interfere with each other. An antistatic agent, for example, loses effect when a slip agent occupies the surface first. Other conflicts occur within the material: halogenated flame retardants and other acidic components reduce the effectiveness of HALS stabilizers, and certain minerals adsorb part of the additive and leave it inactive. That is why compatibility is reviewed against everything that goes into the hopper.

Interaction between the additive and the pigment

Color also plays a part. High-surface-area pigments, such as some organic pigments and carbon black, can adsorb part of the additive and reduce its effect. The color of the part also changes the amount of ultraviolet protection it needs: carbon black provides its own barrier, while a light or translucent shade depends mainly on the stabilizer. Conversely, some additives shift the shade: antiblock reduces transparency and gloss, and certain ultraviolet absorbers give a slight yellow tint. That is why the color is approved with the additive included in the sample.

Two ways to add the additive to the color in the machine

Parallel dosing: one concentrate per function

The most flexible way is to dose the color and the additive as two separate concentrates, with two feeders or with a premix in the hopper. This way each one is adjusted independently, the same additive serves all the colors at the plant and the function is removed when an order does not need it.

This approach requires discipline. Each feeder is a calibration point, each shift records two percentages and a poorly prepared premix can separate in the hopper. Both carriers must be compatible with the base resin.

A single concentrate with color and additive

The other way is to formulate a single concentrate that carries the color and the additive in the same let-down ratio. The plant loads one product, the risk of forgetting a second bag disappears and the proportion between color and function is fixed from the laboratory. That fixed proportion is also its condition, because the laboratory needs to know the end use and the downstream process from the start.

Total masterbatch loading in the part

With either approach, it is advisable to add up everything that goes into the hopper. For example, a color at 2%, a slip agent at 1% and an ultraviolet protection at 1.5% add up to 4.5% masterbatch, and most of that percentage is carrier resin. In polyolefins with carriers from the same family, that loading usually goes unnoticed. In thin film or in engineering plastics, the compatibility of each carrier begins to show.

What to define before requesting an additive masterbatch

For the concentrate to solve the problem without creating another one, we recommend arriving at the quotation with these data:

• The problem you want to correct: film that sticks, high friction, static, moisture, sun exposure, odor, bacteria or traceability.

• Polymer, grade and process, with the resin's technical data sheet to know which additives it already carries from the producer.

• Downstream processes: printing, lamination, sealing, assembly or food contact.

• The color it will be combined with: code, pigments, carrier and let-down ratio of the current color masterbatch.

• Wall thickness or film gauge and, for outdoor parts, the expected exposure and service life.

• Your plant's dosing method: number of feeders and use of premix.

With that information, the dose is also calculated for what happens after the machine.

The additive concentrates we formulate at Delta Pigmentos

At Delta Pigmentos we formulate additive concentrates according to each customer's specific requirements, for plastics, paints and inks. Our catalog brings together seven families: Antibacterial AG, Delta Bio, UV markers, desiccants, ultraviolet protection, MB Aroma, and biocide and repellent. We also handle requirements for slip, blocking and static control, and we propose the additive in powder or masterbatch form depending on your process.

The work follows three steps. You share your polymer, your process and the function you need. Our laboratory formulates the concentrate for that polymer and that process, and proposes the additive loading. You receive the recommended let-down ratio and validate it in your own production before committing volume. When the additive accompanies a color, we review both formulations together. We produce under ISO 9001-2015 certified procedures and ship anywhere in the country from Santa Anita, Jalisco.

Frequently asked questions

Can I dose the additive and the color separately on the same machine?

Yes, with two calibrated feeders or with a homogeneous premix. It is advisable to confirm that both carriers are compatible with your resin and to record both percentages on every shift.

How much additive masterbatch is used?

It depends on the concentration of the additive in the pellet, the function and the thickness of the part. Additives act in small amounts, so the concentrate is dosed at low percentages. Our laboratory proposes the loading and the let-down ratio, and you validate them in your production.

Can an additive change the color of the part?

Yes. Antiblock reduces transparency and gloss, some ultraviolet absorbers give a yellowish tint and certain pigments adsorb part of the additive. That is why it is advisable to approve the shade with the additive included in the sample, at the actual thickness of the part.

At Delta Pigmentos we have been manufacturing color, white, black and functional masterbatch in our own plant for 24 years, and we formulate custom additive concentrates with our own laboratory and ISO 9001-2015 certified procedures. If your part or your film needs an additional function, or the additive you use today conflicts with your color or with your customer's process, write to us on WhatsApp from https://deltapigmentos.com with your polymer, your process, the color you use and the problem you want to correct; we will respond with a technical proposal. Every request is reviewed within the following 24 business hours.