Non-stick surfaces and coatings are becoming more and more common in our day to day, especially within the household appliance and household goods sector. We all have non-stick saucepans, pans or molds in our house that facilitate our work in the kitchen, but do we know how the non-stick effect is achieved in the products we use? The answer to this question is very simple, non-stick coatings.

Non-stick coatings, such as Teflon, are applied to kitchen and household products to prevent food from sticking and to facilitate subsequent cleaning.

However, due to its excellent properties, this type of coatings can also be used in other sectors to improve the functionality of many products. For example, they can be used in the automotive sector, to improve the cleaning of interiors, windshields or filters, to avoid clogging and improve the performance of different equipment.

For this reason, within our area of functional surfaces, we seek to take advantage of the great benefits of these coatings to improve the surface properties of any product or material. In today’s blog we tell you how these non-stick coatings work, the types that exist and how they can be incorporated into the materials and products that we want to improve

What is a non-stick coating and how does it work?

A non-stick coating, as its name suggests, is one that seeks to reduce the adherence between the surface of a material and the products that are deposited on it. For example, in the case of pans, the coatings that are deposited are thought to reduce the adhesion between food, or oils, and the metal of the pan. In other applications, the coatings will seek to reduce adhesion with other different products. Next, we show you a coating applied to a piece of a paint tunnel to reduce adherence with the paint from the tunnel and avoid its subsequent cleaning.

In all cases, the coating must be deposited on the surface of the material to be protected. Later we will tell you how to carry out this application correctly, since, if it is not done well, the coating may not have the expected effect or fail prematurely.

To achieve the non-stick effect, these coatings act through physical and chemical mechanisms, which affect 2 fundamental properties of adhesion: surface energy and adhesion forces.

Surface energy is the attractive or repulsive force that a surface exerts against another product. The higher the surface energy, the greater the attractive force on the surface. On the contrary, the lower the surface energy, the lower the attractive forces. For this reason, a non-stick coating seeks to minimize the surface energy of the material where it is deposited. In this way, it is possible to reduce the adhesion forces between the materials.

Types of nonstick coatings

Currently, there are different non-stick coating options on the market. All of them have great properties, however, depending on the final application, it may be more interesting to select one or the other. Next, we present the most used non-stick coatings:

  • Non-stick based on tetrafluoroethylene (PTFE)

    This substance is what provides the non-stick properties to this type of coatings. Within this group we find the best-known non-stick product on the market, Teflon, present in our kitchens, construction products, medicine, etc. This type of coatings are inert and do not pose a risk of toxicity, however, in the past they considered toxic due to the presence of perfluooctanic acid (PFOA). Currently, this toxic compound is no longer in its composition.

    PTFE-based coatings probably offer the best results today, however, their low resistance must be taken into account, since they deteriorate quite easily under the action of external agents such as temperature, abrasion or chemical agents. among others.

    To solve this problem, it is possible to reinforce PTFE-based coatings with other elements, such as titanium, which provides hardness and resistance to the coating.

  • Ceramic sol-gel non-stick

    In this case, the coating is based on the dispersion of ceramic particles in a liquid medium, in this case gel. Once mixed, the colloidal suspension of particles can be applied to the surface of a product to give it non-stick properties.Compared to PTFE-based coatings, ceramic coatings are harder and better resist high temperatures, however, their non-stick properties may be somewhat lower than those provided by PTFE-based ones.

  • Siloxane-based non-stick

    This type of non-stick are based on achieving the same principle of non-stickness as silicones. Siloxanes are organic compounds with non-stick properties that can be applied to the surface of any product to give it these properties. We leave you an example of a product where we have applied it.

     

    The main advantage of these siloxane-based coatings is that the radicals can be modified to give them different non-stick properties. Among these properties, the contact angle and the slip angle stand out.

Within each of the 3 groups of non-stick coatings, we find different options, depending on the needs of the product where it is to be applied. For this reason, it is very important to know the functionality that you want to obtain and the conditions of use that will be given to the product, in this way you can choose the best non-stick coating.

Additionally, by applying microstructures on the surface, the roughness of the materials can be modified to achieve the non-stick effect physically. At ATRIA we have combined the application of microstructures and coatings to achieve a joint action of both technologies.

How to add a non-stick coating to a material

One of the most critical points when using a coating on a product or material is its application. This stage is key, since it is necessary to achieve a correct union between the coating and the final product.

At ATRIA, before industrializing the use of a coating, we define the application process to avoid the problems derived from poor adhesion between the coating and the product to be improved. To do this, we optimize the following stages:

  1. Cleaning the surface. As with paints, before applying a coating it is essential that the surface is completely clean. Depending on the product and coating, different cleaning agents can be used.
  2. Surface activation. On many occasions it is advisable to carry out an activation process of the surface where the coating is to be deposited. This activation makes the coating adhere better to the surface. To carry out this activation there are different options (flamed, plasma, ozone, etc.)
  3. Application of the coating. The application can be done by dip-coating or spraying. Depending on the industrialization and the type of product, the most suitable option is chosen. Both options must be perfectly optimized to ensure the correct deposition of the coating and thickness.
  4. Cured. Finally, many coatings require a curing stage. This stage must be carried out correctly to avoid degradation of the coating.

How to evaluate the efficiency of a coating

To ensure the proper functioning of a coating, our testing and quality team is in charge of evaluating the efficiency of all the coatings we study. In this way, we can choose the one that offers the best benefits to the final application.

To evaluate the efficiency, we measure the contact angle that the liquids form with the coating. We carry out this characterization with our tensiometer, which allows us to deposit controlled drops and take an image of the angle they form with the surface.

Furthermore, we can calculate the surface energy of the coating by depositing drops of 3 liquids with different polarity. In this way, we have fully characterized the coating and ensure the correct result in the final product.

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