When plastic isn’t fantastic
By Graeme Peters
An Agcarm member
sent me unsettling
photographs of four
different pesticide
products sitting on a
shop shelf.
The rationale for
sharing the snaps
was that the products
looked far from
normal. Grody would
be a better description. The problem was the packaging. It was badly deformed or ‘sucked
in’. Those in the know call this panelling.
Looking at the pictures, it was easy to leap to the conclusion that this manufacturer was
cutting corners. Instead of using appropriate packaging, the company was pinching pennies,
using a cheap plastic unsuited for the product and the environment in which it could be
stored (such as a tin shed on a hot summer day).
I approached the company in question (not an Agcarm member, I should point out) to
discuss the packaging. The chief executive said that all the company’s products were in
appropriate packaging.
Perhaps. Perhaps not.
It later became clear that packaging problems – mostly cosmetic, but some more serious happen to most manufacturers, even those with global brands who try to do everything right.
Rather than pointing the finger of blame, members asked Agcarm for best practice guidance
on packaging that met the requirements for a variety of products, and satisfied the
regulators.
The resulting guidance, available on the Agcarm website, is summarised here:
How does packaging damage occur?
Damage can be caused by a product reacting with the packaging during storage, changing
the chemical make-up of the product.
For example, crop protection products might react with oxygen, reducing the pressure inside
the container. Chemicals might also migrate through the packaging. If the walls aren’t strong
enough, the partial vacuum causes the packaging to distort or suck in.
The opposite problem can occur if chemical reactions in the container result in gases being
formed. Pressure builds within the package.
All of these problems can be avoided using the right packaging technology.
Most packaging material for crop protection products is plastic. To maintain the shelf life of
crop protection products, the correct type of plastic must be used.
What types of plastic are used?
The most common plastics are high-density polyethylene (HDPE), or HDPE mixed with other
plastics or with added polymer layers.
These plastics are strong and chemically inert, so they shouldn’t react with the product.
HDPE is usually used for water-based products.
HDPE mixes (eg, HDPE and polyamide) are used for solvent-based products.
Other plastic containers are treated to stop the product damaging, reacting with, or migrating
through the plastic.
What treatments are available?
Some containers are treated or lined to control any unwanted chemical activity. Examples
are fluorine gas treatment and fluoropolymer linings.
Fluorinated containers are plastic drums that have undergone a special treatment to make
them safe for packaging certain chemicals that react with plastic.
The process of fluorination bombards the plastic with fluorine ions. This replaces the
hydrogen atoms on the outside of the packaging with fluorine atoms, which are larger,
plugging holes in the plastic so product can’t escape and air can’t get in.
Using plastic containers that are fluorinated is a solution for providing strong, light
packaging.
Facilities to fluorinate plastic containers are not available in New Zealand so Agcarm
members either ship their containers to Australia to be treated, or import product in
fluorinated containers
Another option is membranes. These line the container and may be incorporated into the
caps of containers to let gases pass in and out.
Some liquid crop protection formulations with a very low viscosity can clog the micro-pores in
the membrane.
To counter this there are different types of membranes - some repel water, others repel oils.
This helps prevent liquids from leaking through the membrane.
To equalise the pressure in a container, another solution is to use vents, preventing
packaging deformation.
Is packaging regulated?
Packaging is included in the registration of a product by the Ministry for Primary Industries
(MPI) and the Environmental Protection Authority (EPA).
Packaging is also covered by land transport legislations and multiple agencies are
responsible for administering various aspects of dangerous goods transport and storage. For
a fuller explanation of these requirements, go to the Agcarm website.
In summary, there is a range of actions that manufacturers can take to minimise risks of
packaging failure.
Unsightly panelling can be avoided through the selection of appropriate plastic, fluorination,
linings, membranes, and pressure valves.
If four products from a single manufacturer at a single store are panelling, it’s a fair bet that
the packaging is not fit for purpose. Either that or the manufacturer assumes that its
customers are unconcerned about it
Agcarm manufacturer members are more interested in ensuring that their products are
safely packaged. This is not to say that problems do not occur, but there is more emphasis
on getting it right.

Graeme Peters is the chief executive of Agcarm, the industry association for
companies which make and sell crop protection products.