The Company And The Problem
Safe Reflector is a manufacturing company specialising in products that are reflective such as bags, clothing, wrist bands and much more. They are a large manufacturer dealing with high volume and because of this quality is very important. A product recall, a bad reputation in the market place or a dangerous product could all cost the company significantly.
One problem they had was with print adhesion on to portable spray canisters that are used by customers for sanitising liquids and sun protection cream. A low surface energy material coupled with chemicals that can dissolve many printing inks lead to poor print adhesion and a quality problem needing to be solved.
Trying to solve the problem lead Safe Reflector to look in to chemical pretreatment and primers to obtain good adhesion, which did work but customers could tell the products had been treated due to unpleasant smells on the product.
Safe Reflector needed a new, environmentally friendly, discrete and sensible way of preparing the products for printing.
Investigating Corona Treatment
The products are made of polypropylene which is an excellent material for containing these liquids because it is an inert polymer that will not leak or react with the liquid inside. It does however have a low surface energy and it’s inert properties mean it is tricky to get good adhesion.
The first challenge was obviously to improve performance of print adhesion. Using the right ink for these applications is critical because many inks will dissolve or smudge when rubbed with sun cream or sanitiser because of the chemicals they contain.
Printing on to polypropylene or similar materials such as polyethylene (PE, HDPE, LLDPE etc.) which are lightweight, robust and chemically stable when containing liquids like sun cream and sanitisers is often challenging.
Having a solvent like chemical in the packaging makes the challenge even harder as when the user gets the product on their hands, it will inevitably get on to the outside of the bottle.
Poor adhesion coupled with the wrong ink being used which isn’t resilient to the product means that the product quality is poor.
The problem can be seen for many manufacturers, including this one used in our home!
The second challenge is to treat the entire product which was around 50mm, relatively wide treatment coupled with the production speed requirement to match print rate.
One big request was that treatment takes place on both sides of the container. This could be so print can be applied to both sides, or to avoid any doubt or loading considerations.
Possible Solutions For Print Adhesion
There are three or four key machines that could be used for this kind of problem, taking a quick look at each we will start with plasma:
Vacuum Plasma
| Speed | Vacuum Plasma systems can be small or large, even custom built so a design could be suited to the volume of products required. |
| Integration | Batch processing would mean that an operator would be continually loading and unloading the machine. |
| Performance | Excellent adhesion and both sided treatment as standard. |
| Cost | Relatively high cost to buy a system large enough to treat the required volume. |
Vacuum Plasma chambers can be standard like the 2020 and 5050 machines but for smaller parts the use of the custom built machines are sensible.
Custom vacuum plasma systems allow you to pick the exact height between shelves and tailor things such as integration and automation for automatic doors and integration into other systems as well as the vacuum pump used for process speed as well as a few other points.
Read What Is Vacuum Plasma? if you want to know more about the technology!
Atmospheric Plasma and SpotTEC
| Speed | Atmospheric plasma can cope with at least 30m/min but could go over 100m/min. SpotTEC would likely have a max speed of 20m/min. |
| Integration | Both systems could easily be integrated inline as bolt on additions or in a custom built conveyor system. |
| Performance | Excellent adhesion from both, however SpotTEC could leave some marks on polished surfaces. |
| Cost | Well priced systems especially if simply bolted on. |
SpinTEC Atmospheric Plasma ranges from around 100mm of treatment up to 150mm treatment width so could cope easily with treating the part.
One major consideration for this technology with small parts like these mouldings is the air flow which is usually a minimum of 30L/min compressed air at 4bar+.
Small components can easily be blown around and holding the part somehow is required.
Read What is Atmospheric Plasma? if you want to know more about this technology!
Corona Treatment
| Speed | Corona treaters can vary their speed easily as power can be increased or decreased based on the speed of the line. |
| Integration | Integration using a conveyor system is very easy and standalone. They can also be integrated into existing lines without the need for changing existing safety circuitry. |
| Performance | High performance and easy to treat both top and bottom of parts. |
| Cost | Mid to high costs for these systems as they are often engineered to meet specific criteria rather than standard plasma nozzles. |
Corona treatment is an effective treatment that can easily cope with higher line speeds, wider treatment and be integrated well in to moving production lines.
It’s common for treating web materials and this has been it’s strength for many decades, but treating semi 3D components is highly beneficial and is often seen in medical device manufacturing as well as other industries looking for permanent print or adhesive performance.
Read What is Corona Treatment? If you want to know more about Corona Treatment!
The Solution
Safe Reflector chose to work with corona treatment as it met their production needs and gave them the product quality they wanted.
”We had major challenges with the adhesion of digital print to our sprayers and were looking for a collaborator who could guide us to the right solution. After thorough research we found that Tantec should deliver a Corona treater to us”, says Tomas Radikas, Sales Manager, who, in addition to being pleased with Tantec as a collaborator, also can report better production efficiency.
This type of solution is sensible as it’s flexible for a variety of product sizes and will give perfect and repeatable treatment every time. It’s also a machine that requires very few consumables and has low running costs.
This means that the entire machine can usually run at around 2kW which is energy efficient and environmentally friendly, requiring no chemicals, primers or other hazardous consumables.
Watch the snippet video of the machine in action alongside dyne testing showing treatment of the material taking surface energy from less than 30 dynes to over 60 dynes.
