Kortec Readies 144-Cavity Coex PET Preform Mold

One equipment maker is going to NPE in Chicago with new technology and bright prospects. Kortec Inc. designs and assembles coinjection systems for pet preforms. Business is good despite the downturn, says John N. Kermet, vp. of sales, and demand for the Beverly, ma, company’s technology is robust.

Kortec will unveil designs for a 144-cavity preform system at NPE, June 23-27, double what it introduced in January. The company, which usually adapts its technology to Husky injection machines, will also report on plans to work with press maker Arburg on lower-volume pet coinjection systems.

Kortec is on the leading edge of a growing market — coextruded pet preforms. Kermet says depending on container size, barrier resin, and ambient conditions, coextrusion can increase bottle barrier by a factor of 2 to 4, well within the shipping and storage requirements of carbonated soft-drink distribution.

But the company is also a technology innovator and, according to Kermet, unique in several respects:

• It claims to be the only company selling turnkey preform coinjection systems. Most others are proprietary;

• Molds fit on smaller injection machines than those from competitors;

• Cycle times keep pace with monolayer preform molding.

Kermet says the strategy is to match the latest capabilities of monolayer preform molding, hence, 144 cavities, which follows developments at market leader Husky. The Kortec system processes any barrier resin that can be used with pet, and does so with molds that fit on smaller machines. The 72-cavity mold, new in January, runs on a 300-ton Husky press. A 72-cavity mold (photo) normally requires a 500- or 600-ton machine. The 144-cavity mold is designed to run on a 600-ton press.

He concedes that this may be the practical limit on preform cavitation, even though the company could go higher. A 144-cavity mold produces about 300 million preforms per year. Since most companies prefer to divide production among smaller machines than concentrate it on one or two large presses, it’s unlikely that there would be much demand for bigger molds. Kermet says the company could produce a 256-cavity mold. But with annual production of 500 million preforms, none but a handful of the largest bottlers would find it practical.

In fact, Kermet notes there is plenty of demand for low-volume molds for specialty containers and regional markets, which is why the company is working with Arburg. Kortec will use Arburg’s smaller machines for molds of no more than 8 cavities, which produce 5 million to 10 million preforms/yr.

Kermet declines to detail Kortec’s coinjection technology, but offers some information.

The company uses simultaneous rather than sequential or valved injection. Kermet says this yields cycle times equivalent to monolayer molding.

The hot-runner channels for the pet and barrier resin are integrated; both feed the same nozzle. This requires combining two manifolds in a special design. To compensate for heat differences between pet and a resin like evoh, which processes 100°C lower, integrated cooling technology is used within the core manifolds for optimum temperature and to control thermal expansion. Cooling techniques include special steels in the mold and hot runner, and how water is circulated through a mold.

Hot-runner nozzles have no moving pieces. The three-layer flow (inner layer/barrier/outer layer) runs through what Kermet terms three dies in the nozzle. This creates an annular, laminate flow to the gate.

Meanwhile, manifolds and mold assemblies are low-profile. The components do not stack directly when assembled; rather, they integrate with each other to reduce overall size. This is one reason why Kortec can fit high-cavitation molds on smaller injection machines.

Kermet believes that Kortec’s preform technology will find wide use in beer bottles, the “holy grail” of pet applications. Promising markets are in Eastern Europe and China, and in specialty applications like stadiums and beaches in the U.S.

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