Tag Archive: plasma treatment

1. How Surface Treatment Functionalizes & Activates Difficult Bonding Surfaces

   August 4, 2022 6:30 pm Leave a Comment

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   Many secondary processes prior to decorating and bonding require strong adhesion to be successful. However, certain substrates have insufficient surface energy for creating the required bond strength. To bond these types of challenging materials, surface treatment such as plasma or corona treatment significantly improve adhesion. This article will discuss some of the most common bonding challenges and outline how surface treatment overcomes these difficulties.

   What Is the Purpose of Surface Treatment?

   Surface treatment is used to improve bonding or “functionalize” the surface of a substrate. This useful technology modifies the surface of a material in a way that allows for strong bonds to be formed between the substrate and a label, a coating, print, or adhesive. Surface treatment, such as atmospheric plasma (also called in air plasma) and corona treatment work by improving surface tension. Numerous bonding problems are successfully solved through surface treatment, even those involving elastomeric or polymeric materials.

   

   There are significant costs associated with bonding failure, including poor product field performance, excess scrap and rework, production inefficiencies, and increased quality control. Surface treatment solves virtually any bonding challenge, even when using the most difficult-to-bond materials.

   Corona and plasma surface treatment prepare materials for improved adhesion by:

   • Raising the material’s surface tension or wettability by altering the molecular properties of the surface 
   • Improving the bond strength between the applied media and the material
   • Plasma treatment provides mechanical etching and micro-cleaning, as well as elevating surface tension

   Bonding Items With More Than One Type of Material

   

   Note how the ink on the left side of the corona treated polystyrene tray fully bonds with the material, but beads up on the non treated right side.

   Materials that feature low surface energies, such as those between 20 and 40 dynes, are notoriously difficult to bond. In plastics, this includes materials such as polytetrafluoroethylene (PTFE), polypropylene, and polyethylene, polystyrene, among others. Composite materials are also challenging in bonding applications because the different materials they contain typically feature differing surface energies. 

   Achieving workable wettability of a substrate requires the surface energy of the substrate to exceed the surface tension of the media being applied. Using surface treatment to increase the substrate’s surface tension causes media to evenly flow and adhere to the material’s surface for highly improved bonding capabilities. 

   How to Activate the Surfaces of Difficult-to-Bond Materials

   When activating the surface of challenging materials, the first consideration should be the surface energy of the substrate. The surface energy will determine whether or not media will successfully bond with the material. Wettability is another prerequisite of successful adhesion. The term wettability describes the ability a liquid has to maintain contact with a type of media. It is influenced by intermolecular interactions that are altered through corona and plasma surface treatments.

   Atmospheric plasma is created by combining reactive gas molecules and an electric field. This system uses one or more high voltage electrodes, which charge the surrounding blown gas molecules, resulting in a highly ionized field that is forced onto the targeted surface. This ionized air stream reacts with the substrate and breaks the existing hydrogen bonds by introducing oxygen which recreates the chemical properties of the surface. This intensified reaction causes the material to wet out and accept media, as well as etches and micro-cleans the surface.

   3DT’s plasma treatment is not confined to a chamber, but performed in fast, inline production lines. What’s more, plasma is environmentally friendly and potential-free, meaning it can be used on or near metal parts and wiring.

   Corona treatment also improves a material’s surface tension to solve bonding problems. It is probably the most common and economical type of surface treatment. In contrast to plasma treatment, corona relies on two electrodes and an isolator to create a cloud of ionized air, corona discharge, that breaks molecular bonds on the surface of a material. Surface oxidation occurs, creating covalent bonds resulting in enhanced wettability and adhesion capabilities.

   3DT works closely with its customers in selecting the most appropriate surface treatment method for their application. Factors such as the materials and media involved, the geometry, line speed, and required bonding results are considered. See our blog article What is the Process for Purchasing a Surface Treatment System from 3DT? for more information.

   

   Custom PolyDyne Pro corona treatment system with indexing table for the treatment of labware flasks.

   Surface Treatments for Powerful Adhesion from 3DT

   Working with materials that are resistant to printing and bonding requires surface treatment processes that improve surface tension and eliminate bonding problems. 3DT manufactures a comprehensive line of surface treatment systems to improve bonding for numerous applications. Our solutions raise surface energy and improve bonding on even the most challenging substrates.

   With over 30 years of specialized experience, 3DT provides the most innovative corona and plasma treatment systems. Our equipment addresses the needs of diverse industries and can be used as stand-alone stations or incorporated into a production line. We specialize in process development for demanding applications. Learn more by visiting our corona and plasma treatment process page, or get started on your solution by requesting a quote today. 
   

2. Corona vs. Plasma Treatment

   July 23, 2021 9:59 pm Leave a Comment

   For more than 30 years, 3DT LLC has been a leading provider of specialized corona and plasma surface treatments for customers around the world. Our state-of-the-art systems can be used as stand-alone stations, incorporated into new and existing production processes, or integrated into fully or semi-automated production lines. With 3DT’s 2- and 3- dimensional treating systems and a wide variety of custom configurations, we have a solution for virtually any application. In addition to manufacturing our cutting-edge equipment, we offer services such as design, manufacturing, product handling, installation, training, and maintenance service.

   One of the more common questions we field about electrical surface treatment is, “What is the difference between corona and plasma treatment?” and then, “What best fits my application?” Both corona and plasma treatment increase the surface energy of numerous materials improving the adhesion of inks, adhesives, coatings, and other agents. However, they both have unique properties that require consideration in terms of applications.

   

   In this post, we discuss the advantages and uses of corona treatment vs. plasma treatment, to aide in your understanding. However, our sales team will actively guide you in selecting the best system for your material, process and application.

   What is Corona & Plasma Treatment?

   How Does it Work?

   Corona and plasma treatment are both forms of electrical surface treatment. They use the power of electrical energy to change the chemical properties of material placed within an energy stream. This stream of electrically loaded molecules causes an intensified reaction with the material resulting in better wettability and stronger bonding traits. Electrical surface treatment is highly suitable for three-dimensional polymer parts, thin film, rubber profiles, glass labware, metal parts, coated paperboard and thicker materials such as foam and solid sheets of material.

   When this phenomenon is contained inside an electrically grounded chamber, an air stream can be introduced to this chamber to force the plasma outwards in a controlled fashion and onto materials in a process called plasma treatment or atmospheric plasma treatment. However, when an insulator is placed between the two electrodes, the avalanche effect is avoided and the result is a cloud or arc of ionized air. This ionized air – Corona Discharge – can now be used for the surface treatment of a wide number of materials that show poor or no adhesion properties to media such as printing inks, adhesives, etc.

    

   

                                            Illustration: Corona Treating Head

   What’s the Difference Between Corona & Plasma Treatment?

   Plasma discharge has a relatively narrow treating width but is capable of imparting enormous surface energies onto substrates.  Plasma has the added benefit of cleaning residue and contaminants from surfaces and even etches surfaces for the added benefit of increasing bonding with media. Plasma discharge is virtually potential-free so it can be used to treat conductive materials such as metal and alloys. 3DT’s PlasmaDyne systems offer a variety of types of plasma treating heads that can be quickly mounted onto existing lines with little setup. A unique benefit of our system is that the discharge level is adjustable for numerous applications. Plasma also produces no ozone gas which is a natural byproduct of the corona process.

   Alternatively, corona discharge typically imparts less surface energy but can treat large areas. Corona treatment also has the advantage of being able to treat inside parts or in the recesses of 3-dimensional parts. Both methods are very effective in functionalizing surfaces for better adhesion. Check out the video below.

   Our Most Popular Treatment Systems

   3DT designs and manufactures an extensive range of cutting-edge surface treatment products, including:

   MultiDyne™

   3DT’s MultiDyne™ corona treatment system creates optimal surface tension, or wettability, on a broad range of parts and materials. Featuring repeatable and process controlled operation,  MultiDyne™ is typically used to prepare blow molded, injection molded, and extruded parts and products. MultiDyne™ creates highly effective, uniform adhesion on surfaces for printing, coating, gluing, and lamination.

   MultiDyne™’s state-of-the-art corona discharge technology works by creating a short circuit between two high voltage electrodes. A constant flow of air between the electrodes facilitates even distribution of the corona field onto the surface of the treated material, creating a highly receptive adhesive surface. It is perfect for treating areas that are commonly a challenge for other surface treatments, including applications with complex geometries, hard-to-reach areas, and metal-adjacent surfaces.

   PolyDyne™

   PolyDyne™ is one of 3DT’s most powerful corona treatment systems. This extremely dependable and reliable system is particularly useful in high-speed operations, such as printing, extrusion, assembly, and coating production lines. PolyDyne™ is exceptionally versatile and can be used to treat everything from the interior surface of needle hubs to automotive components. Using the latest technology, PolyDyne™ directs corona treatment with an exceptional degree of precision onto virtually any surface.

   PolyDyne™ is specifically designed with flexibility in mind. All of our systems can be customized to meet the particular needs of your application, including variety and number of treating heads, custom electrode systems, ozone eliminators, and material handling systems. For more resistant materials, we are pleased to offer our PolyDyne Pro™ system.

   PlasmaDyne Pro™

   

   PlasmaDyne Pro™ uses a stream of highly ionized plasma to modify the chemical properties of the surface material within the stream. The surface becomes functionalized and highly receptive to chemical bonding. This system also cleans and etches substrates for added bonding properties. PlasmaDyne Pro™ is unique within the industry because only 3DT’s technology offers adjustable treatment/power levels. This benefit increases treatment options regarding flexibility in substrates, parts, and treating modes all within one system.

   PlasmaDyne Pro™ enhances the adhesion of ink, paint and adhesive to a wide range of components, from plastic tubing and medical devices to rubber automotive seals and metal parts. 3DT’s PlasmaDyne Pro™ is a compact, versatile system, with an optimized control unit, the highest in treatment levels and modular replacement parts that facilitate non-stop production. PlasmaDyne Pro™ is completely customizable. Let’s discuss your application today!

   Premium Surface Treatment Systems by 3DT

   At 3DT, we are committed to developing superior surface treatment systems for every industry.  We have spent decades at the forefront of corona and plasma technology and are dedicated to solving even the most complex adhesion challenges. To learn more about our surface treatment systems and related services, visit our product page, or contact our experts today.

    

    

3. Reviewing Surface Treatments: Decorating, Printing and Bonding on Plastic IS Possible

   July 14, 2020 5:03 pm Leave a Comment

   

   This plastic bottle has been plasma-treated in the center only. Note how the ink bonds to the surface where treated but beads up where the bottle was not treated.

   From Plastics Decorating Magazine’s Enews July 2020

   By Gary Kohlnhofer, Senior Sales Engineer, 3DT LLC

   Polymers have many useful properties, making them the material of choice. Polypropylene and polyethylene are prime examples. However, polymers typically have insufficient surface energy and poor wettability for most printing and bonding applications. Fortunately, corona and plasma surface treatment modify the surface of polymer substrates and raise their surface energy for printing, coating, painting and adhesive applications. As a result, the usefulness of polymers greatly increases for decorating and bonding applications.

   Let’s take a look at each of these methods of surface treatment, their applications and benefits:

   What is corona treatment?

   Corona treatment makes use of a generator and high voltage transformer to create a high voltage/high frequency corona discharge applied through an electrode with small airgap onto the surface to be treated. The result is a cloud of ionized air – or corona discharge – which then is used for the surface treatment of plastics and other materials.

   A substance placed under the corona discharge is impacted by electrons with energy two to three times that necessary to break the molecular bonds on the surface. The resulting free radicals rapidly react with the oxidation of products in the corona discharge or with adjoining free radicals on the same or different chain, resulting in a cross-link. Oxidation of the surface increases the surface tension or surface energy, allowing for better wetting by liquids and promoting adhesion.

   

   In the photo to the right, MultiDyne’s discharge treats ampules before printing.

   How is corona used in relation to plastics decorating?

   Corona treatment often is used inline on web-based printing machines, such as for treating label materials. Films such as polypropylene and polyethylene, for example, are treated inline prior to the digital printing decks to increase the surface tension and improve wettability and adhesion of digital inks. With these inline corona treating systems, the web is threaded over a treater roller and high voltage/high frequency power is applied to the electrode resulting in corona discharge through a small airgap. Corona treating systems also can be used on a high-speed cup decorating line, treating the cup on a mandrel prior to the printing decks.

   What types of applications or surfaces is corona treatment better suited for and why?

   Corona discharge effectively improves the surface tension on numerous materials that show poor or no adhesion properties to media, such as printing inks and adhesives.

   

   This MultiDyne system with two treating heads and a conveyor is designed for improving adhesion on small parts.

    

    

    

    

   Corona treating systems lend themselves to many applications, such as inline printing presses, but discreet parts can be treated as well with custom conveyor-based systems. A conveyor-based system using rotating electrodes treats different shapes and sizes without set up changes.

   These systems are very user-friendly and provide for uniform, repeatable surface treatment and high production rates. Individual parts also can be treated in fixtures with corona treatment delivered by custom electrodes and generator configurations.

   What are the benefits and challenges of this particular treatment?

   The benefits of the corona treatment process include the ability to print on substrates that otherwise would not be possible. Users also benefit from better print quality and faster printing line speeds, resulting in higher production and output.

   What is plasma treatment?

   Plasma surface treatment (also called in-air and atmospheric plasma) improves the wetting properties of polymeric materials, rubber, metals, glass, ceramics, paperboard and more. The molecules of these difficult-to-bond materials are modified by the plasma process to obtain better adhesion without causing harm to the surface.

   

   PlasmaDyne PRO rotating head treats a metallized plastic part to improve adhesion of ink/paint.

   Atmospheric plasma is created by combining reactive gas molecules and an electric field. This technology uses one or more high voltage electrodes which charge the surrounding blown gas molecules, resulting in a highly ionized field that is forced onto a targeted surface. This highly ionized air stream creates a thermal property that reacts with the substrate and breaks the existing hydrogen bonds by introducing oxygen which recreates the chemical properties of the surface. The atmospheric plasma process causes an intensified reaction with the material, resulting in better wettability, stronger bonding traits and micro-cleaned surfaces.

   How is it typically applied/integrated into the workflow?

   Plasma treating systems often are placed just prior to printing on inline printing production lines. The plasma treating head is mounted above a profile allowing the material to pass under the treating head and then the printing head improving the adhesion of the digital inks. Alternately, individual parts can be placed in a fixture then inserted into a plasma treating system set up to index the treating head back and forth over the parts, treating the top surface of the parts. Once treated, this fixture can be inserted into the digital printer for improved printability thanks to plasma treatment.

   

   Here PlasmaDyne PRO is fitted to a robotic arm to quickly plasma treat defined areas of parts.

    

   What are the benefits and challenges of this particular treatment?

   Because atmospheric plasma is nearly potential-free, one important advantage is that plasma treatment can be incorporated into conductive, semi-conductive and non-conductive applications.

   Plasma is effective for cleaning surfaces by removing impurities, contaminants, residue and organic compounds. This process, called micro cleaning or etching, provides another important aspect in improving adhesion. What’s more, surface activation by plasma treatment is exceedingly fast, effective, economical and environmentally safe.

   What are 3DT’s surface treatment options for printing and decorating on plastics?

   3DT LLC provides a complete line of corona and plasma surface treating systems designed to overcome many adhesion challenges.  We offer standard and custom-built systems and application development.

   

   Our 3DT FlexiDyne PRO system is a conveyor-based corona treating system that utilizes rotating electrodes to provide a wider treat area and uniform, repeatable treatment with high production rates.

   In order to treat individual parts and profiles, we can provide a corona treating system using our 3DT PolyDyne generator and high voltage transformer technology and electrode system designed specifically for the part/profile to be treated.  Especially useful is our 3DT UltraDyne generator package designed for high speed cup and tube printing and decorating applications. UltraDyne provides consistent, strong high-frequency treating where other systems can’t.

   

   For surface treatment utilizing plasma technology, we offer our 3DT MultiDyne low frequency plasma system as well as our recently updated 3DT PlasmaDyne PRO system.  The PlasmaDyne PRO system with adjustable power output is especially suited for today’s system requirements to be easily adjusted for process changes.

   

   Custom PlasmaDyne PRO system with 8 treating heads and individual adjustments.

    

    

    

    

    

    

    

   Gary Kohlnhofer has 38 years of experience in the plastics industry, 15 of those as Senior Sales Engineer with 3DT LLC. 3DT LLC is a manufacturer of surface treatment equipment, offering standard and custom-built systems and application development. Established in 1991, 3DT has been developing solutions for adhesion and bonding challenges for enumerable applications in all industry sectors. 3DT manufactures a complete line of corona and plasma systems incorporating robust design, proven technology and exceptional customer service with every standard and custom-engineered system. 3DT’s systems are designed and manufactured in Germantown, Wisconsin. For more information, visit www.3DTllc.com.

4. Principle of the MultiDyne: Gliding Arc Discharge

   May 1, 2019 4:28 pm Leave a Comment

   The MultiDyne system operates using the gliding arc discharge principle.  The electrode arrangement is the key to this type of discharge.  As shown in the diagram, the arc forms at the closest distance between the electrodes.  The electrodes are curved to allow the arc to travel between them while increasing in size.  The arc however does not travel along the electrodes without the assistance of airflow behind it.  The airflow is carefully set to maximize the size of the discharge without prematurely extinguishing the arc.

   

   The other major component to maximizing the gliding arc discharge is the specialized high voltage transformer.  The transformer is a dry, oil free, transformer capable of providing over ten thousand volts.  The transformer also offers safety features.  The first of the safety features is the ability for the transformer to current limit itself in the event of a short circuit.  The other safety feature is a center tap connected to ground, reducing the potential between the high voltage leads and ground to 50%.

   Application

   Utilizing the MultiDyne, 3DT has been a solution for numerous industries.  Without the need for a separate ground plate, the MultiDyne is easily incorporated into existing or new product lines.  Adjusting the gap, along with product speed, allows for adjustability of the intensity and size of the discharge on the product.  This allows for most products, regardless of material sensitivity, to be treated.  The size of the arc discharge allows for treatment of three-dimensional objects in addition to flat linear applications.

   The diagram below shows how adjusting the gap alters the width of the discharge.

   

   The MultiDyne system may be designed around a basic principle, but 3DT has developed it into a solid, reliable surface treatment system. Contact our sales team for more information and to discuss your application at 262-253-6700 or sales@3DTLLC.com.

   

   3DT’s MultiDyne 1000 with 1 treating head. Systems are available with 1-4 treating heads depending on the application. Learn more about MultiDyne on our MultiDyne page.

   References:

   Bruggeman, Peter J. “2.6.3 Gliding Arc Discharge.” Low Temperature Plasma Technology: Methods and Applications, edited by Paul K. Chu and Xinpei Lu, CRC Press, 2014, pp. 27–28.