Effect of Application Parameters on Chemical and Mechanical Properties in UV Coatings
Turunen, Vilma (2024)
2024
Master's Programme in Materials Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2024-05-13
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202404103441
https://urn.fi/URN:NBN:fi:tuni-202404103441
Tiivistelmä
The goal of the thesis was to study the effect of different application parameters to the curing of ultraviolet coatings intended for wood substrate. Another purpose for the work was to evaluate and develop further methods for the testing of the achieved cure level from the coating. The chosen test methods for the work were gloss, pendulum hardness, chemical resistance, potassium permanganate stain and mechanical scratching test.
Two different types of UV curing coatings were selected for the work: acrylate lacquer and acylate paint. Samples from the coatings were prepared by changing the application amount and the UV energy that the coating films were exposed to. Substrate used varied depending on the test requirements. Application of coatings was done with single side bar coater film applicator and roller coaters.
The variation in curing level between the samples caused differences in the test results. In some tests the differences between the samples were minor but big differences were also noticed. Usefulness of each test also varied between the two chosen coatings. When comparing the required UV energy to achieve good results from the test performed, it was also noticed that the differences between the tests are big.
From the chemical resistance test the results were good even with the lowest energy levels tested. Based on the testing the R2 and R4 test classification from the IOS-MATT for the UV curing coatings is too easy. Biggest difference noticed from this test was between the two different application amounts from the same products. With thicker film thickness the results were slightly better than with thinner film.
Usefulness of the gloss and pendulum hardness test varied between the two different coatings chosen. Gloss varied more during the testing with the matt lacquer sample and the effect of lowering the curing energy was visible as the gloss increased when the curing energy was lowered. Same effect was not achieved as distinctive with the pendulum hardness. With the paint on the other hand the usefulness of the two tests was opposite to the lacquer. The gloss remained stable during the testing of the paint, but the pendulum hardness lowered when the curing energy was lowered.
In the potassium permanganate stain test the difference between samples were big even with minor changes to the curing energy The difficulty in the stain test was in the rating of the results. Creating a suitable rating criteria for this test was not achieved during the analysis done in this thesis.
Mechanical scratching was performed as a single scratch test. The type of the surface defect caused by the scratching varied between the two coating types. Due to this, rating criteria that could be used for the evaluation of the defect of different type of coatings was not made based on the testing done in this thesis.
From the application parameters the most limiting factor according to the test results was the film thickness of the coating. With too thin film thickness the films did not cure properly due to the oxygen inhibition phenomena. Too high film thickness in the other hand required more UV energy to cure.
Two different types of UV curing coatings were selected for the work: acrylate lacquer and acylate paint. Samples from the coatings were prepared by changing the application amount and the UV energy that the coating films were exposed to. Substrate used varied depending on the test requirements. Application of coatings was done with single side bar coater film applicator and roller coaters.
The variation in curing level between the samples caused differences in the test results. In some tests the differences between the samples were minor but big differences were also noticed. Usefulness of each test also varied between the two chosen coatings. When comparing the required UV energy to achieve good results from the test performed, it was also noticed that the differences between the tests are big.
From the chemical resistance test the results were good even with the lowest energy levels tested. Based on the testing the R2 and R4 test classification from the IOS-MATT for the UV curing coatings is too easy. Biggest difference noticed from this test was between the two different application amounts from the same products. With thicker film thickness the results were slightly better than with thinner film.
Usefulness of the gloss and pendulum hardness test varied between the two different coatings chosen. Gloss varied more during the testing with the matt lacquer sample and the effect of lowering the curing energy was visible as the gloss increased when the curing energy was lowered. Same effect was not achieved as distinctive with the pendulum hardness. With the paint on the other hand the usefulness of the two tests was opposite to the lacquer. The gloss remained stable during the testing of the paint, but the pendulum hardness lowered when the curing energy was lowered.
In the potassium permanganate stain test the difference between samples were big even with minor changes to the curing energy The difficulty in the stain test was in the rating of the results. Creating a suitable rating criteria for this test was not achieved during the analysis done in this thesis.
Mechanical scratching was performed as a single scratch test. The type of the surface defect caused by the scratching varied between the two coating types. Due to this, rating criteria that could be used for the evaluation of the defect of different type of coatings was not made based on the testing done in this thesis.
From the application parameters the most limiting factor according to the test results was the film thickness of the coating. With too thin film thickness the films did not cure properly due to the oxygen inhibition phenomena. Too high film thickness in the other hand required more UV energy to cure.