Adhesion refers to the mutual attraction and molecular force of the contact parts of two different substances. Moreover, it will only be present if the molecules of these two substances are very close to each other. Two solids are generally not allowed to come into close contact and the adhesion between them does not have an effect, whereas a liquid can be in full contact with the solid and has an adhesion effect. For example, there is adhesion between the paint and the object being painted.
The adhesion of the paint film introduced in the article refers to the firmness of the surface of the object coated by the paint film under the influence of physical and chemical forces. The adhesion of the paint film is one of the key indicators to evaluate the performance of the paint film, and the quality of the adhesion is directly marketed to the quality of the entire supporting coating. Only when the paint film is well attached to the surface of the coated object can it play its due role in protection and decoration. This paper mainly focuses on the three national standards for paint film adhesion testing, and compares and analyzes each method.
The full text is as follows:
The adhesion of the paint film refers to the communication between the paint film and the surface of the object to be attachedThe degree to which physical and chemical forces are combined. lacquerThe adhesion of the film is one of the important indicators to evaluate the performance of the paint filmThe quality of the force is related to the quality of the entire supporting coating. Paint film onlyIt is well attached to the coated object in order to exert its due protectionprotection and decorative effect, in order to achieve the purpose of applying coatings, otherwise that isSo that the coating has good protective and decorative properties, but due to the adhesion is notIt is also meaningless to cause a large piece to fall off. The current largeMost product standards have requirements for the adhesion of the paint film, so the paint filmThe research work on adhesion determination methods has been widely usedSet store by.
First, the adhesion mechanism of the paint film
The adhesion mechanism of paint film can be roughly divided into mechanical adhesion and chemicalizationLearn to attach two kinds. Mechanical adhesion depends on the nature of the sheet being coatedand the mechanical strength of the resulting paint film; Chemical adhesion refers to paint films and platesThe interface between the materials, the paint film molecules and the sheet molecules attract each otherforce, depending on the physicochemical properties between the paint film and the sheet.It is generally believed that the adhesion of the paint film depends on the polymerization of the film-forming substanceThe polar groups of the compound, such as -OH, -COOH, and the surface of the coated objectPolar groups are bound to each other. Where to reduce this polarity knotVarious factors will lead to a decrease in the adhesion of the paint film. Such asThere is pollution and moisture on the surface of the coating material; The coating film itself has a large shrinkageStress; The polymers are cross-linked with each other during the curing process, which consumes polaritythe number of bases, etc.
2. Paint film adhesion test standard
There are currently 3 effective national standards for the determination of paint film adhesionItem:
1 . GB/T 1720-79(89)In this system, the template is fixed on a flat that can be moved from front to backOn the stage, while the platform moves, it is used as a stylus stroke for circular movementsPaint permeable film, and can draw the lines of overlapping round lines, from the lines of round linesObserve the position of the paint film failure in the texture to judge the level of adhesionOther.
2 . GB/T 9286 -1998Scratch test》Equivalent ISO 2409 -1992 "Paints and varnishesGrid Test. This method is used according to the thickness of the sample substrate and paint filmThe spacing cutter cuts the lattice pattern of the paint film to make it just rightIt is good to penetrate into the substrate and press the surface where the paint film comes off from the substrate in the scratched areaproduct to determine the level of adhesion.
3 . GB/T 5210-85 "Determination of coating adhesion -- Pull-offLaw》Refer to the international standard ISO 4624 -1978 "Pigment andVarnish adhesion pull test method. The method is determined by the attachedForceful force is applied on the cemented surface of the specimen at a specified speedVertical, uniform tensile force to determine between coatings or between coatings and substratesThe force required in case of adhesion failure is expressed in MPa.
3. Comparison between the three methods
A comparison of the 3 national standard test methods is shown in the table below
IV. Conclusion
The results measured by the above 3 paint film adhesion determination methods are eachSelf-independent, no conversion relationship, they all have their own advantages and disadvantages, we shouldAccording to the actual situation, select the appropriate method to determine the adhesion of paint filmforce
