The surface treatment technology changes the material properties and creates a surface layer with mechanical, physical, and chemical characteristics distinct from the base material.
The goal of surface treatment is to satisfy the product’s unique functional requirements for corrosion resistance, ornamentation, and other factors. A surface treatment method known as the plasma treatment technique is used to create the ideal polymer surface for inks, paints, and coatings to cling to.
This article explores the plasma surface treatment, how the process operates, its best uses, and where it is applicable. Read further to learn in-depth knowledge.
What is Plasma?
The foundation of plasma, the fourth state of matter, is a straightforward physical idea. When energy is applied to matter, solids become liquids, and liquids turn into gaseous states. If we add energy, gas molecules get ionized when heated and carry a net positive charge. When enough molecules are ionized, a plasma is created to change the gas’s overall electrical properties.
What Is Plasma Surface Treatment?
The term “plasma surface treatment” refers to a procedure that can change or increase a material’s surface energy to enhance its capacity to take a coating or be bonded to another material.
The treatment is tailored for adhesive and paint applications and influences various coating materials that promote adherence—applying plasma treatment to the surface results in an extremely thin, high-tension coating surface ideal for bonding, coating, and printing. Materials that are either too hydrophilic or too hydrophobic for their intended use can be treated with plasma.
Plasma technology is used for surface treatment processes like cleaning, coating, printing, painting, and adhesive bonding and is often the industry standard for handling metals, glass, papers, and plastic polymers.
Why Is Plasma Surface Treatment Used?
Plasma surface treatment is primarily used to clean, improve the adherence of surfaces, and create thin coatings.
1. Plasma Cleaning
Plasma cleaning prepares a surface by eliminating all organic debris from various materials in a vacuum chamber. It produces a pristine surface ideal for bonding or further processing without creating harmful waste. Additionally, this process can significantly lessen contamination concerns than traditional cleaning methods.
In the plasma, energetic oxygen species also carry out cleaning functions by interacting with impurities to predominantly produce water and carbon dioxide. During this cleaning process, organic contaminants are blasted away by plasma-activated ions, which break them down so they may be evaporated and evacuated from the chamber.
2. Surface Activation
A polymer material surface is frequently prepared for bonding or printing via plasma surface activation. The polymer is broken down, and free radicals are produced when energetic species are exposed to the surface chemistry. Although oxygen is frequently required in this procedure, many plasma activations can be carried out using room air.
3. Plasma Coating
Plasma surface treatment cleans the material’s surface of foreign impurities, making it more acceptable for processing. The plasma coating method applies a nanoscale polymer layer to an object’s surface. The resulting coating has no color, no smell, and has no impact on how the material feels or looks, leading to permanent coating.
4. Plasma Etching
Plasma etching removes silicon, plastic, and other non-metallic materials by exciting ions in a gas to form plasma. Without chemical etchants, the material is removed when the excited ions collide at the atomic level. For a consistent etching process, ion density, electron temperature, and plasma potential must be controlled.
How Does Plasma Surface Treatment Work?
Plasma treatment occurs when a gas is subjected to an energy source like electricity or a microwave. The gas transforms into a mixture of ions, radicals, free electrons, and other molecular fragments. The process by which all traces of organic contamination are eliminated is the subsequent plasma treatment.
A plasma nozzle, gas delivery pipeline, and plasma generator comprise the plasma surface processor in plasma treatment. The workpiece’s surface is covered in plasma. The object’s surface to be processed alters as the plasma touches it, and chemical reactions occur.
The working of plasma surface treatment can be divided into atmospheric and low-pressure or vacuum.
● Vacuum Plasma Treatment
An evacuated chamber or enclosure can be used for plasma therapy. Before the energy in the form of electrical power is supplied, the air inside the chamber is pumped out to create a high vacuum environment. Then the gas is allowed to flow into the enclosure at low pressure.
Remember that the plasma treatment is essentially a low-temperature procedure, making it possible to process heat-sensitive materials efficiently. Vacuum plasma is used as a plasma technology because the lack of gas molecules within the chamber allows the plasma treatment gas to diffuse more effectively once it has been injected into the chamber.
Typically, the therapy gas can diffuse more effectively as there is less chance that the treatment gas will collide with other gas molecules in the chamber to scatter and reroute.
● Atmospheric Plasma Treatment
Using atmospheric “jet nozzle” plasmas is another method of treating surfaces. Atmospheric plasmas function at atmospheric pressure. They are most worthwhile when used with a robot or for the localized treatment of parts in an in-line process.
Tools and Equipment Used For Plasma Surface Treatment
The two main pieces of equipment used in the plasma surface treatment process are a chamber and an evacuated enclosure. As plasma therapy works at low temperatures so, this equipment aid in the process of creating that ideal temperature and high vacuum inside the chamber. The atmospheric jet plasma is another device for treating plasma. For various techniques, various plasma treatment machines are used.
Plasma cleaning machinery with PP film and UV coating can be plasma processed to make the water-based adhesive adhere firmly. While its fantastic technology also improves surface tension, it prevents adhesive and bonding breaks and offers the ease of cleaning various surfaces. It effectively clears mineral debris from surfaces and removes surface oxidation. Additionally, it is used to clean ceramics and prepare the surfaces of plastics and elastomers.
Industrial producers in assembly, printing, and decorating industries benefit from reproducible adhesion process control provided by plasma equipment such as flame surface treaters. Plasma surface treatment frequently replaces the requirement for risky primers and inadequate hand surface preparations.
What are the Pros and Cons of Plasma Surface Treatment?
The pros of plasma surface treatment are endless; a few of them are as follows:
- Infinite chemical alterations may be made by selecting suitable gases or chemicals.
- Processing of plasma is more environmentally friendly than other surface treatment methods.
- Due to its minimal chemical consumption and lower chemical plus water expenses, surface modification offers a financial benefit over traditional wet processing.
- Additionally, this technique for surface modification uses less water and energy to dry the treated materials.
- In-line plasma treatment equipment improves surface adhesion on composites, plastics, metals, and glass surfaces.
- Plasma has the potential to completely irradiate hazardous, poisonous chemicals since it has the energy to modify the atomic structures of substances.
- Plasma is already employed as a highly accurate scalpel in medical procedures. Hot plasma could be used in medicine to drill cavities and sterilize and cauterize wounds.
- Plasma surface treatment is a low-cost treatment as compared to other surface treatments.
- Adhesive bonding with adhesives, sealants, varnishes, and paints is encouraged by plasma treatment.
On the contrary, the plasma treatment also possesses some limitations that include:
- Determining the depth of plasma penetration can be daunting.
- Adaptation mechanisms can be hard to manage.
- Investment cost can also be an issue in plasma surface treatment.
- Finding the effective dose of plasma for various materials can be challenging.
Industrial Applications of Plasma Surface Treatment
Plasma surface treatment is found in various industrial applications, some of which are discussed below:
1. Packaging Industry
Packaging industries use plasma surface treatment to glue and seal beverage or jam bottles in order to ensure the firmness and reliability of the package. It mainly helps to solve the lamination glue and UV opening problems.
2. Automobile Industry
Plasma helps to treat the automobile’s bonding surface, which leads to properties including tighter bonding, sound insulation, and moisture-proof and dustproof—on the other hand, using plasma as a pre-printing treatment guarantees no color fading or falling of paint. Usually, plasma surface treatment is used for automobile brake pads, oil seals, bumpers, etc.
3. Medical Industry
Plasma treatment has exciting applications in the medical industry. Human implant materials are surface treated with plasma to meet comparability. Plus, the bonding of medical catheters is enhanced. This technique also helps in the disinfection of medical equipment.
4. Plastic Industry
Plastic surfaces are plasma treated to increase the adhesion for printing. In addition, different objects are treated to ensure firmness when glued. Usually, plasma surface treatment is applicable to toys, beverage bottle caps, and household appliances.
5. Cable Industry
Wire and cable marking is another application of plasma treatment. Generally, atmospheric plasma treatment encourages the adhesion of aqueous inks, adhesives, and coatings to offer remarkable smudge resistance and abrasion. However, using inkjet markings increases the output yield for cable markers.
6. Textiles Industry
Plasma surface treatment is also applicable in the textile industry. It primarily helps to clean the fibers to enhance their properties, including printability, wettability, fiber capillarity, and dyeability. Hence, in addition to the pre-sterilization of different medical-grade textiles, the ink adhesion plus dyeing of textile yarns, filaments, and webs are improved. It also increases the hydrophilicity and absorption of protein fibers.
Hopefully, this article might have helped you better understand how plasma treatment can benefit the objects to enhance their surface finish and bonding capacity. The wide range of plasma surface treatment applications makes it popular in different manufacturing industries.