What Is Biodegradable Masterbatch, and How Does It Differ from Oxo-Biodegradable Masterbatch?

The blown film plant was manufacturing polyethylene bags for a nut exporter that sold to a European importer. The importer requested "biodegradable" packaging for the following season, and the plant filled the order with an oxo-biodegradable concentrate dosed alongside the brand's brown masterbatch. The bags came out identical to the previous ones, the exporter printed the "biodegradable" claim and the first container shipped on time. At the port of destination, the importer requested the compostability certificate required by its supermarket chain, and the claim had no standard to support it. The exporter had to repack all the nuts in a warehouse at destination, with packaging purchased there, and the plant lost the season's order.

Biodegradable masterbatch delivers color or additives to biodegradable resins without compromising their certification. Oxo-biodegradable masterbatch carries a prodegradant that fragments conventional polyolefins through oxidation. Each one answers to different standards, markets and end destinations.

Two concentrates with the same word on the label and opposite destinations

In the market, the term "biodegradable masterbatch" is used for two very different products. The first is a concentrate formulated to color or add additives to a resin that is already biodegradable, such as polylactic acid (PLA) or polybutylene adipate terephthalate (PBAT). The second is a concentrate added to a conventional polyolefin to accelerate its degradation. They share the word and differ in chemistry, in evidence and in the markets that accept them.

Masterbatch for biodegradable resins: compatible carrier and components

This concentrate uses a biodegradable carrier, or one compatible with the base resin, and pigments that meet the heavy metal limits of compostability standards. Its role is to color the part without taking it outside the scope of its certification. The resin provides the biodegradability; the masterbatch ensures that the color and the carrier remain within the evaluated formulation. It is processed at the low temperatures these resins require and, if the carrier is a polyester, it is dried before use.

Oxo-biodegradable masterbatch: prodegradant in a conventional polyolefin

The oxo-biodegradable concentrate carries a prodegradant additive, usually transition metal salts such as iron, manganese or cobalt, in a polyethylene or polypropylene carrier. It is dosed over the polyolefin like any other masterbatch. With heat, light and oxygen, the prodegradant catalyzes the oxidation of the polymer, breaks its chains and reduces its molecular weight until the material becomes brittle and fragments. The plant processes it the same way as its usual film, and that is where its appeal lies.

Oxidation, fragmentation and biodegradation: three stages that depend on the environment

Oxo-biodegradable technology describes a process in stages, and each stage depends on conditions over which the plant has little control once the product reaches the market.

The abiotic stage: heat, ultraviolet radiation and oxygen

The first stage is chemical. The prodegradant needs energy to activate oxidation: ultraviolet radiation, temperature or both. A film exposed to the sun in a field progresses quickly. The same film buried in a landfill, with little light and little oxygen, progresses very slowly. That is why the degradation time of an oxo-biodegradable product varies widely depending on where it ends up.

Stabilizers and programmed service life

Every commercial resin contains antioxidants that protect it during processing and storage. The formulator balances the prodegradant dose against those antioxidants so that the product retains its properties during its service life and begins to degrade afterward. A hot warehouse, a pallet exposed to the sun or a reprocessing cycle can bring that moment forward. In practice, the dose is defined by the shelf life the customer requires and by the conditions of its distribution chain.

Color, ultraviolet protection and prodegradant in the same film

The prodegradant shares the film with the color masterbatch and the other additives, and several of them act in opposite directions. A HALS-type ultraviolet stabilizer captures the radicals the prodegradant needs to progress; if both enter the same formula, one partially cancels the other. Carbon black absorbs ultraviolet radiation and slows the abiotic stage in a black film. Titanium dioxide behaves according to its form: anatase is photoactive and can accelerate oxidation, while treated rutile protects the polymer. For this reason, the prodegradant dose is defined together with the color and the complete list of additives in the film, and it is validated at the actual gauge and shade.

The biotic stage: what the ASTM D6954 guide evaluates

The second stage would be the biodegradation of the oxidized fragments by microorganisms. The ASTM D6954 guide describes how to expose and test plastics that degrade through a combination of oxidation and biodegradation, in three tiers: abiotic degradation, biodegradation and ecotoxicity of the residues. It is a testing guide; unlike compostability standards, it sets no pass threshold. A report under this guide describes results and conditions, and it should be read in full before it is cited on a commercial data sheet.

The destination market decides which technology can travel

Before choosing the concentrate, the decisive question is where the product will be sold and what claim it will carry. The same bag can comply in one market and require a different certification in another.

Certified compostability: EN 13432 and ASTM D6400

The EN 13432 standard in Europe and ASTM D6400 in the United States require at least 90% of the material to biodegrade within a maximum of six months under industrial composting conditions, in addition to requirements for disintegration, heavy metals and ecotoxicity. Oxo-biodegradable polyolefins fall outside those certifications, because the biodegradation of fragmented polyethylene takes place over much longer periods. To declare a package compostable, the route is a certified compostable resin with a masterbatch that respects its formulation.

What the destination market requires

Each market defines which claims it accepts and what evidence it requires behind them. Some buyers require a compostability certificate, others request a test report and others regulate the use of the word "biodegradable" on the label. That difference explains the problem at the port in the opening case. Recyclers, for their part, point to another issue: if a film with prodegradant enters a recycling stream, the recovered material can carry the additive into a product that was meant to last for years. For an exporter, the requirements of the destination country weigh as much as the technical data sheet of the concentrate.

"Biodegradable" claims without an environment or a time frame

In the United States, the Federal Trade Commission (FTC) guides for environmental marketing claims call for competent and reliable scientific evidence that the entire product will break down within a reasonably short period of time after customary disposal. A "biodegradable" claim alone, on a package that will end up in a landfill, is unlikely to meet that criterion. The claim should state in which environment and within what time frame the product degrades, with a test to support it.

How to choose between a concentrate for biodegradable resin and an oxo-biodegradable one

The choice starts from the end destination of the product and its market. We recommend defining the following information before requesting a quote:

• End destination of the product: industrial composting, landfill, recycling or outdoor exposure.

• Market of sale and applicable regulations, with particular attention to export products.

• Exact claim your customer plans to print and the standard or test that will support it.

• Base resin, grade and process, with its technical data sheet.

• Required service life and storage and distribution conditions.

• Documentation the end customer requires to approve the package.

On the plant floor, each option calls for different precautions. The concentrate for biodegradable resin is processed at the temperature of that resin and must be dried when the carrier is a polyester. The oxo-biodegradable concentrate is processed like a polyolefin masterbatch, with two precautions of its own: stable dosing, because the service life depends on it, and segregation of recovered material, so that the prodegradant stays out of the plant's durable products.

The biodegradable line we offer at Delta Pigmentos

At Delta Pigmentos we have been manufacturing masterbatch in our own plant for 24 years. Within our additives line we offer Delta Bio, an oxo-biodegradable additive for polyolefins, and our color catalog includes a biodegradable line in red, magenta and green. Before recommending any of them, we review with you the end destination of the product, the market of sale and the claim your customer plans to print.

With that information, our Quality Control, Design and Development laboratory proposes the option that fits your case and the dosing for your process. You validate the sample in your own production before committing volume. We produce under ISO 9001-2015 certified procedures and ship anywhere in the country from Santa Anita, Jalisco.

Frequently asked questions

Can I declare a polyethylene bag with an oxo-biodegradable additive as compostable?

A compostable claim requires compliance with a standard such as EN 13432 or ASTM D6400 for the finished product, and polyolefins with prodegradant fall outside those requirements. For compostable packaging, the route is a certified compostable resin with a masterbatch compatible with its formulation.

Does the oxo-biodegradable additive affect film recycling?

Recyclers warn that the prodegradant can travel with the recovered material into products that must last for years. It is advisable to segregate recovered material that contains the additive and to inform whoever receives the material of its presence.

Can a masterbatch with a biodegradable carrier be used to color polyethylene?

The appropriate choice is a carrier from the same family as the base resin. A PLA carrier in polyethylene melts and disperses differently, and it can leave specks or streaks in the part. Each resin calls for its own concentrate.

Masterbatch for biodegradable resins and oxo-biodegradable masterbatch meet different needs, with different standards, markets and destinations. At Delta Pigmentos we help you choose the option that fits your product, with our own laboratory and ISO 9001-2015 certified procedures. Write to us on WhatsApp from https://deltapigmentos.com with your resin, your process, the destination market and the claim your customer plans to print; we will respond with a technical proposal. Every request is reviewed within the following 24 business hours.