Injection molds in beakers as an example of rigid PVC compounding
Application

Polyisobutylene (PIB) as a gum base for chewing gum

PIB is often used in the basic mass for chewing gum, the so-called “gum base”.

Polyisobutylene (PIB) belongs to the olefine polymer family. It has been manufactured commercially since the 1930s and is produced with a wide viscosity range from oil-similar to raw rubber-like masses. Here, its properties largely depend on the average molar masses.

Since the early 1980s, the potential of continuous process management has also been recognized for gum base manufacturing and been used increasingly since then. The constant, reproducible and uniform product quality, short residence times, gentle treatment of sensitive formulation components, precise and fully automated process control, reduced salary costs, low specific energies and therefore reduced energy costs and last but not least reliable and mathematically modelable scale-up processes belong to the major reasons there. BUSS compounding technology is designed for these requirements in the gum base area.

Typical areas of application

Gum base ingredients, chewing gum and fresh mint
White gum base pellets from a gum base compounding line
Woman chewing chewing gum manufactured with gum base
Individually packed polyisobutylene chewing gum
White gum base granulates from a gum base compounding line

In addition to the technical applications which are described on the corresponding pages, PIB is often used as an elastomer formulation component in the basic mass for chewing gum, the so-called gum base. As opposed to the natural rubber originally used, the individual requirements profiles of the type, brand and manufacturer-specific features can be mapped very well with the wide range of different PIB variants and together with the further formulation components.

Further insights into our options for the food industry

Benefits

BUSS compounding systems offer the following specific benefits

Latest generation multiple-flight BUSS compounders achieve a better mixing effect with a low overall specific energy input. This is because there is a high number of mixing cycles, optimally attuned to the respective process zone. The energy required for melting is almost exclusively introduced mechanically (dissipated) as shear energy.

The BUSS Kneader allows precise temperature control due to controlled energy input and uniform, moderate shear rates as well as their temperature monitoring by thermocouples, which are mounted in drilled kneading pins surrounded by polymer at relevant positions along the process section.

The BUSS Kneader guarantees intense distributive mixing, as the superimposition of rotation and axial movement of the mixing and kneading screw causes flow separations and a large number of shearing surfaces, thereby generating cross-channel mixing.

Screw elements, liners and kneading pins are BUSS gum base compounder technology components which are easy to replace and easily accessible by opening the hinged process section of the BUSS Kneader. All these elements can be replaced without removal of the casing or the screw shaft.

Injection pins, which can be mounted in the BUSS Kneader at any position along the process section, allow liquid components to be injected directly into the molten polymer at the optimum location for the process. The mixing process begins immediately, without smearing on the barrel wall and enables mixing over the shortest possible process length.

Compounding requirements

for gum base

In the compounding process for gum base, it is important to mix the formulation components optimally in the viscous phase. BUSS compounding technology is ideally suitable for this. The elastomers (PIB) and also the liquid rubber shares are melted or masticated via the dissipated kneader shaft shear energy in the first zone of the BUSS Kneader.

In the second zone, the fillers and epoxies are dosed additionally and mixed in. The synchronised course of dissipative and distributive mixing processes via the oscillating and rotating screw shaft is particularly effective here. The waxes, plasticizers and antioxidants, which often exist as liquids, are fed to the optimal process position via hollow-drilled kneading pins.

In the third zone, in addition to further homogenisation of the gum based, reworking material can also be integrated. Thus, it is possible with a process length of only 11 L/D to process the product gently with first-class product quality at high throughput. Due to the short dwell time and excellent self-cleaning properties, it is possible to work with on-the-fly product changes, thus optimizing availability.

The mass thus prepared can then be further processed inline. For this purpose, it is normally pumped into a heated intermediate storage container. Alternatively, shaping takes place for further processing offline.

This can be a granulation (e.g. hot cutting) or pelletizing (e.g. Rotoform) process or also classical molding of slabs using sausage-shaped gum base extrudates lying next to each other. Thanks to its technologically outstanding features and highly efficient operating system, the BUSS Kneader has become the reference for compounding technology for gum base processing. Our numerous customers are well aware of the excellent options and therefore opted for a BUSS Kneader technology several decades ago.

Typical plant layout

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LR Kneader

Polyisobutylene

The plastic polyisobutylene (PIB) belongs to the olefin polymer family. It has been manufactured industrially since the 1930s and is produced within a wide viscosity range from oil-like to raw rubber-like masses.

Plant and System Solutions

Custom compounding systems from BUSS: tailor-made concepts, integration of all components, precise assembly, and smooth commissioning. Comprehensive expertise results in sustainable compounding solutions for a wide range of material applications.