Comparison of methods for determination of coating adhesion
The determination of film adhesion is of great significance in the coating industry, as it assesses the physical and chemical interactions between the film and the substrate. This paper will discuss the determination method of film adhesion and its significance, and analyze the advantages and disadvantages and application scenarios of four different determination methods.
Experimental principle
The purpose of the determination of the adhesion of the coating is to observe the damaged state of the coating by applying destructive external forces (grid, circle, twist, pull) to judge the ability of the coating to not fall off the substrate. This method according to the experimental principle, the use of different instruments and steps, such as sharp blade, winding adhesion tester, torsion adhesion tester, tensile testing machine.
Step method
The determination of film adhesion includes many methods, such as grid method, circle method, cutting method, twisting method and pulling method. Among them, the grid method is evaluated by cutting the surface of the coating to form a small grid; the circle method is used to judge the adhesion by drawing a circular rolling line pattern; the cut mark method is used to observe the adhesion by using a variety of intersecting cut marks; the twist open law is used to measure the force required for the coating to twist away from the bottom plate; and the pull open law is applied in the test to measure the adhesion between the coatings.
Comparison of methods for determination of coating adhesion
1. Grid method:
Preparation: Obtain the test sample and ensure that the sample surface is dry and clean. Prepare cutting tools and tape.
Experimental steps:
Use the cutting tool to cut 6 parallel marks on the surface of the film, cutting through the entire depth of the film.
Make 6 more cuts perpendicular to the previous direction to form small squares.
Apply the tape to the entire grid, then peel it off at the smallest Angle, and observe the proportion of the area where the film is removed.
According to the situation of the film falling off, the adhesion level is assessed by reference.
Comparison of methods for determination of coating adhesion
2. Circle method:
Preparation: Prepare the adhesion tester and test sample.
Experimental steps:
Use the adhesion tester to draw a certain length of overlapping circular line pattern on the film.
According to the intact degree of the coating film, the adhesion level of the coating film is evaluated in turn.
Comparison of methods for determination of coating adhesion
3. Cutting method:
Preparation: Prepare cutting tools and test samples.
Experimental steps:
Use cutting tools to make different sizes of cut marks, and form different areas of cut marks on the film.
Adhesion is assessed based on the size of the cut mark and the peel of the film.
4. Twist open method:
Preparation: Prepare the twist adhesion tester, test sample and adhesive.
Experimental steps:
The probe of the tester is bonded to the film of the sample to be tested using a adhesive.
Twist the instrument 90° with appropriate force to determine the torque required when the paint film is twisted open, that is, equivalent to the twisted adhesion of the film under test.
Comparison of methods for determination of coating adhesion
5. Opening method:
Preparation: Prepare the drawing adhesion meter, specimen and adhesive.
Experimental steps:
Uniform tension is applied to the bonding surface of the sample to determine the force required per unit area between coatings or when the coating is pulled apart from the substrate.
According to the operation steps of the tensile testing machine, the specimen is stretched until it is broken, and its adhesion and failure form are assessed.
Method comparison
When comparing different assays, we need to take into account the advantages and limitations of each. The operation of the grid method, the circle method and the cutting method are relatively simple, and the results are easy to observe and judge, but sometimes they can not show the adhesion property of the film completely accurately. The twist and pull methods require more complex instruments and procedures, but can more accurately evaluate the bond between the coating and the substrate, and are suitable for different construction scenarios and laboratory conditions. Taking into consideration, various determination methods have different advantages in practical applications, and the choice of the appropriate method depends on the actual situation and the characteristics of the film to be evaluated. In the coatings industry, the accurate evaluation of coating adhesion is crucial to the control of product quality, so it is necessary to choose the appropriate measurement method according to different scenarios.
| method | principle | advantage | limitation |
| Grid method | The adhesion was assessed by cutting the film to form small squares and observing the area being shed | Simple to operate and easy to implement | The results are subjective and cannot provide accurate quantitative data |
| Coil method | The adhesion tester was used to draw the circle and roll lines of different parts to judge the film integrity | The results are intuitive and easy to read, providing quantitative level assessment | The result is influenced by the operator’s subjective judgment |
| Notch method | By making different sizes of cut marks to observe the adhesion, forming different areas to evaluate | Provide a variety of adhesion level assessment, relatively objective | The operation is more complicated and still affected by the subjective factors of the operator |
| Turn-off method | The adhesion is determined by twisting the torsional adhesion tester in the vertical direction | Provide accurate quantitative data to assess the bond strength of the coating to the substrate | The operation is complex and requires specialized equipment |
| Pulling method | The adhesion is assessed by a tensile testing machine applying uniform tension to the specimen surface | Provide more accurate quantitative data to evaluate the adhesion properties of the coating surface | The operation is more complex, and it is difficult to evaluate the adhesion of the edges and corners of the paint |
Comparison of methods for determination of coating adhesion
Significance and application
Coating adhesion is directly related to the durability and performance of coatings. Excellent adhesion means that the film adheres firmly to the surface of the substrate, providing better protection and decorative effects. In practical applications, the correct determination of film adhesion can guide product design and process flow, improve product quality and service life. The determination methods of film adhesion are various and have their own characteristics, and appropriate methods should be selected according to the actual situation and needs. Accurate evaluation of film adhesion is helpful to guide the production and application of coatings, improve the quality of coatings and extend the service life of products.