The Swiss injection molding machine manufacturer Netstal will produce double-layer barrier preforms for milk bottles using the overmoulding process.

The PRELACTIA® barriers will be introduced at the Drinktec international food and beverage technology exhibition next month in Munchen.

Netstal will produce double-layer PRELACTIA® barrier preforms for milk bottles using a PET-LINE 2400-4000/1000.

In particular, milk products and drinks with a long shelf life can be packaged safely, economically and in a manner that is visually appealing when using PRELACTIA®.

At Drinktec 2017, Netstal will demonstrate the production of a PRELACTIA® barrier preform for 0.5-liter milk bottles using a PET-LINE 2400-4000/1000.

The additional 1000-series injection unit is positioned in a so-called L position toward the main injection unit. During the first step of the overmoulding process, a 1 mm-thin gray layer with integrated light barrier is injected into the 32+32 cavity mold of the Spanish mold manufacturer Molmasa.

The blank is then coated with a 1.4 mm-thin pure white outer skin. The total cycle time of the application presented at the trade fair is 9.0 seconds. Piovan provides the systems for the drying of the material and dehumidification. The water cooling is made available by EF Cooling. The PET granulate and the color master batches are supplied by Total Polymers.

“To flexibly balance capacity fluctuations during the manufacturing process, the PET-LINE 2C can also be used to easily produce preforms for non-carbonated beverages or CSD preforms. The software deactivates the secondary injection unit,” said Stefan Kleinfeld, Product Manager Beverage at Netstal.

PRELACTIA® offers a better light barrier while also sharply reducing the use of titanium dioxide.

The double-layer structure of the patented barrier preforms offers an enormous economic benefit compared to other processes. To produce pure white milk bottles, the white pigment titanium dioxide is added to the polymer for the production of the preform.

The additive also provides an increased barrier effect against damaging UV light. For single-layer preforms, the proportion must be at least 15% of the preform’s entire weight. When using PRELACTIA®, however, the additive is only mixed into the outer layer, which allows the proportion of the additive to be reduced to five percent of the weight of the preform.

“In the context of a yearly production of 105 million preforms at 17 grams each, the use of the high-grade titanium dioxide is reduced to around 180 tons. At market prices between €7-8 per kilogram, this results in enormous annual savings. At the same time, the customer benefits from a significantly improved light barrier effect compared to single-layer PET preforms,” explained Kleinfeld. Nearly 100 percent of the visible light is reliably blocked.

This makes PRELACTIA® particularly well-suited for milk products and milk drinks with a shelf life of up to six months. Since both layers are made from PET, empty PRELACTIA® bottles can simply be put in a regular recycling bin.

Plastic and Chemical Trading services the plastics industry, specifically automotive, extrusion, logistics packaging and consumer packaging, with focus on bottling and food packaging industries.

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