Plastics are the perfect raw material for many applications and products. They are easy to process and can easily be fine-tuned with certain properties such as flame retardancy. So-called compounds are ideal for this – a mixture of polymers, fillers and additives that together offer the desired properties. However, there are also more and more applications where “batches” are required to meet the growing demands.
Hardly any product today can do without plastic. Whether cladding on and in vehicles, electrical fuses or a number of everyday objects – they are all largely, if not entirely, made of plastic. Depending on the application, the material must have specified properties and often comply with legal standards and regulations.
Comprehensive flame protection, i.e. the ability to prevent the spread of fire and the generation of smoke and toxic gases in the event of a fire, is one of the essential properties required of many products today.
Fire protection requirements increase
The demand for halogen-free flame-retardant plastic components in particular has recently gained in importance. On the one hand, more and more standards, for example in the cable or railway sector, take into account aspects such as smoke density and toxicity in addition to fire propagation. On the other hand, the idea of sustainability demands more and more halogen-free solutions.
Today, flame-retardant materials must not contain halogen, among other things, because halogen-containing flame retardants release corrosive, toxic vapours in case of fire. In this context, halogen-free materials often bear the abbreviation HFFR (Halogen Free Flame Retardant).
As a compromise, low-halogen plastics are currently still used for some applications.
The most common fire classes, which are also reflected in the standards and require the use of HFFR components, are V0 and V2 according to UL94-V. UL stands for “Underwriters Laboratories”. The internationally active organisation with headquarters in the USA has developed more than 1,300 safety standards, many of which are American National Standards (ANSI).
For these reasons, there are more and more HFFR compounds on the market. However, there are still restrictions on certain properties. For example, V0 for phosphorus-based, halogen-free flame retardant systems requires a relatively high flame retardant content of 20 to 35 percent. However, this means that other properties such as impact strength suffer as a result.
XINOMER offers compounds that meet the V0 requirement and still have excellent other material properties.
Batches gain importance
There are more and more applications in which the use of masterbatches, often just called “batches”, is recommended. Batches are concentrated substances in granular form that are added to the basic material or compound in small quantities, usually between 1 and 10 per cent, but for certain applications also significantly more. This allows additional properties to be added to plastics.
Masterbatches are mainly known from applications in which a compound is to be given a certain colour. In this case, a natural compound is used as the base material. During processing into customer components, for example by extrusion, injection moulding or other processes, the colour is then added in the form of a “batch” in minimal dosage. Typically, this is between 1 and 5 percent.
Continued growth
What many plastics manufacturers do not (yet) know: Masterbatches are also increasingly used in the flame retardant sector. And the trend is rising. According to the study published in April 2021 by Market Data Forecast (www.marketdataforecast.com/market-reports/europe-masterbatch-market), the volume of the European masterbatch market was four billion US dollars in 2020. The experts expect annual growth of around five percent until 2025.
To achieve a V0 fire class, significantly more flame retardant batch must be added during processing than for a colour batch. Depending on the specific requirements, we are talking about 20 to 40 percent admixture.
Now the question arises as to whether or why a manufacturer of plastic components should use a batch when ready-to-use compounds are already available. Ultimately, this depends on various factors.
- Easy processing. Compounds are easy to process. For the addition of batches in the production process, the user needs specific processing know-how and the right equipment. If the latter is not fulfilled, the added batch usually cannot be optimally mixed into the compound, i.e. it may not be evenly distributed in the base polymer.
- Optimal for high flame protection. The higher the flame retardancy requirement, the higher the flame retardant content must be and the more critical the mixing in of a batch during processing (injection moulding, extrusion). For particularly high flame retardancy requirements, a compound is therefore more advisable.
- Certified raw material. In certain cases, not only the finished component but also the compound must be certified (e.g. Yellow Card at UL). In such cases, an HFFR compound is an absolute must and a batch is not expedient.
There are some good reasons for using batches in modern production.
- Universal application. Batches can be used universally within the same polymer family. For example, if a processor uses several polymers for HFFR components, he can use one and the same batch for certain properties.
- Efficiently.For certain applications, compounds are “overengineered”. The batch content, however, can be flexibly adjusted by the processor. By setting the necessary flame retardant content via batch, he can use only as much flame retardant as is necessary or prescribed by the standard. On the one hand, this saves costs, since flame retardants are more expensive than base polymers. On the other hand, it leads to better mechanical properties, because the more flame retardant is added, the worse the mechanical properties are.
- Individually dosing. It is not uncommon for a processor to have to produce plastic components in different geometries, such as different wall thicknesses, but at the same time achieve the same fire class for all parts, for example V0. Here he can make use of the fire tests. Based on these tests, he can set the exact batch dosage for each of his components. This increases his cost efficiency.
- Flexible.Certain batches are also used as “boosters”. In this case, an HFFR compound is already present, with which some components just do not pass the fire test. This can happen with a portfolio of different components with different geometries, especially with thin-walled parts. By adding a few percent booster batch, the components in question then pass the test.
- Cost effective. Batches are often a more cost-efficient alternative to compounds. It is true that batches are more cost-intensive to purchase than compounds due to the high load of expensive flame retardants. But since they are mixed with cost-efficient standard polymers such as PE or PP during processing, this results in a lower price per kilo than a comparable compound.
Conclusion
Whether an HFFR compound or an HFFR batch is the better solution varies from case to case. The answer depends, among other things, on the application, the specific flame retardancy requirements and the market.
If you have any questions about this: XINOMER develops and distributes both HFFR compounds and HFFR batches. Our experts will be happy to advise you individually. Get in touch with us.
For HFFR compounds or flame retardant masterbatches click here!
