With corona treating, the goal is to increase the materials surface energy to provide wet ability and adhesion. But, treating a plastic film or substrate can be ineffective when the system is not properly run and maintained. So you must be aware of how to effectively process the various materials or substrates.
Over or under corona treating can transfer too much energy to a plastic substrate which is where a lot of problems could occur when printing or converting of plastic material. When attempting to obtain satisfactory printing results on under treated material can result in the use of excessive amounts of ink in an effort to try to make up for the low treatment levels. Over treatment can result in damage to the material itself as well as problems with the plastic film or plastic tubing blocking together Coronatest Drachten.
Poor ink adhesion, or low dyne levels can occur. How you can establish a good starting point is with the power level. You begin by working your way u until the anticipated dyne level is achieved this is done through quality assurance checks of the plastic film. Once the power level is established for the given product at the given speed, note the power level so when your next time you run the same material and machine speeds you will have a set standard and can be assured of desired repeatability.
Plastic film converters can achieve proper treat levels through trial and error. Testing protocols which include adhesion and bond strength measurements at a variety of power levels should be used to determine the acceptable power level for each substrate or material type, material thickness, and even material suppliers are all variables which can impact the appropriate power level. Once determined, the appropriate power settings should become a permanent part of the job specification.
Accurate web tension effects plastic film treatment which if not controlled properly can cause variances in surface treatment. With too much tension the material can wrinkle or snap whereas a lack of tension creates air gaps between the material and roll. In both cases the material can become unevenly treated. Also can cause another problem called backside treating.
Materials that do not come in close contact with the treater roll under the electrode or back up roller can affect the treatment process. Wrinkles in the material or air getting trapped under the material can result in some treatment of the back side of the material which will result in reduce treatment level in respect to the top part of the material and may cause the material to stick together or block.
There are ways to ensure proper tension is to consider nip rolls as they will eliminate concerns with developing an air pocket between the back up roll and the plastic film. Also in some cases you may want to have a spreader roll or a crowned roll to help eliminate any wrinkles especially at higher production speeds.
Maintaining the surface treatment equipment is very important to help reduce long production downtimes. Proper cleaning of the equipment will reduce this downtime.
Many materials tend to clog up or coat the electrodes or air take away systems for example materials like slip and other additives during the corona treatment process.
The material acts like dirt and can be deposited on the rollers or electrodes. The dirt build up can contribute to producing backside treating causes high and low spots on the treater roll which allows for air gaps that changes the variance in the levels of treatment.
This is one thing plastic converters can do is maintain the treater equipment. Inspect the rollers and electrodes when you have a web break, inspect the rollers for un-wanted particles. Assure your exhaust and cooling air is working properly especially during high humidity months. With a little care and designed scheduled maintenance your equipment will last a long time but best of all product quality.