The humble ketchup bottle has gone through many transformations over the years. The most famous one in the world can, some say, trace its design lineage back to ancient Greek vases of the fifth and sixth centuries B.C.

Plastic bottles for ketchup first started appearing on our tables 30 years ago. First they were multilayer extrusion-blow molded PP bottles with an EVOH barrier, then PET multilayer bottles, then HDPE. Today, depending on where you shop and what brand you buy, you can probably find designs based on all three polymers, as well as glass.

 Ketchup Bottle Design

A new packaging from SIPA

Now, responding to calls from several of its converter customers, SIPA has developed a hot-fillable PET ketchup bottle. It should prove a highly cost-competitive alternative to aseptic filling, which is the route currently favoured by at least one leading ketchup producer, and it certainly has better looks than designs in HDPE.

Creating hot-fill bottles takes a lot of technical skill as well as artistry. The problem normally encountered with hot filling plastic bottles, particularly those with long necks sometimes used for ketchup, is that, when the contents cool, their volume reduces and creates a partial vacuum. The bottle walls collapse, and the label becomes partly or completely unstuck.

In the past, ketchup makers have tackled this problem with bottles incorporating panels that withstand the distorting effects caused by the changes in internal pressure. This type of design is very functional, but is not necessarily very attractive.

Strong packaging design and testing

Fortunately, SIPA has strength in depth in design and in testing. Its experts carried out numerous computer simulation tests that provided accurate predictions of how different bottle designs behave after they have been hot-filled. It became clear that something radical needed to be done with the shape of the bottle to stop this vacuum effect from ruining the package.

SIPA’s designers took an existing ketchup bottle design, shortened the neck and softened the angles around the bottle body to prevent the collapsing and provided an attractive appearance. The result is the bottle you see here. It can be filled  between 85 and 90°C, stays in shape afterwards, and prevents “label crinkling”. It’s a bottle that has form as well as function. What’s more, it can be produced on SIPA’s SFR rotary stretch-blow molding equipment equipped with an oven intended for heat-set and oval containers.

Interesting for converters

Several converters have already told SIPA that they are interested in switching from HDPE and from glass to the new PET design. One converter has in fact approved the design already and has carried out its own filling tests with positive results.

Making this type of bottle does require a special PET resin suitable for the heat setting process used for hot-fill containers. The resin also needs to contain an oxygen scavenger to stop the ketchup oxidizing and discoloring over time. With a suitable scavenger, the container can have a shelf life of at least 12 months. SIPA has already carried out successful tests using Amosorb, which is produced by ColorMatrix, a member of the PolyOne group.