Contact angle measurement

Transcription

1 Contact angle measurement contact angle, measured via Laplace-Young for a duration of 10 S ( ) contact angle of different types of hydrophobic coatings on tempered glass ,8 97,8 100,9 GoldSeal GoldSeal Competitor 1 Competitor 2 Spray Aërosol N.A. This test will be used to measure a contact angle of a liquid on a surface All surfaces, (maximum dimensions 15 * 15 cm) Contact angle apparatus from Krüss (DSA 10 MK 2-+ G140) Demineralised water Isopropanol P.A. 6. Testprocedure Clean the sample with isopropanol and blow dry Place the sample under the needle of the apparatus, and let a drop of water (25 µl) fall onto the surface (height from needle to sample : 1cm). Now measure the contact angle via the laplace-young theory, measure with the trackerman for a duration of 10 s. The contact angle as well as the mean contact angle after 10 s appears in the results window. The mean contact angle is the contact angle which determines the result. This procedure will be repeated at least 3 times on the same sample. The resulting contact angle of the sample is the mean of 4 measurements. The higher the contact angle of a sample, the higher the hydrophobicity of the sample. By using the Laplace-Young theory we measure a more realistic contact angle than using any other method (tangent 1, height-width method).

2 Boiling water 1 u 100 C boiling water test : Surface tension measured with permanent marker 38 DYN:CM GoldSeal Glass Coating Competitor 1 Competitor 2 OK NOK NOK Minimun of 1 hour The boiling water test is a test in which we measure the contact angle (see ICT002) after the coated substrate was exposed to boiling water for the duration of 1 hour All coatings - Pyrex beaker - Watch - Electrical heater - Watch glass dish Demineralised water 6. Testprocedure Take a pyrex beaker and fill it with demineralised water (be sure not to overfill the beaker). Place the beaker onto the electrical heater and switch the power on. When the water boils, gently put the sample into the water. Let the sample in the water for exactly 1 hour. Take the sample out of the beaker and let the sample cool off. When the sample is at room temperature, and dry, we can measure the contact angle of the sample (see ICT002). When the contact angle is below 85, the coating has no resistance to boiling water. The results are shown in a table which contains resistance or no resistance for boiling water. If a coating passes the test, we can say that the coating has a good adhesion to the substrate.

3 Chemical resistance CHEMICAL Goldseal Competitor Competitor Coating 1 2 CHEMICAL Goldseal Competitor Competitor Coating 1 2 2% NEUTRAL DETERGENT OK OK OK 100% NEUTRAL DETERGENT OK OK OK 2% OPTICAL 25 NOK NOK NOK 100% OPTICAL 30 OK NOK OK 2% OPTICAL 30 OK NOK OK DIACETONALCOHOL OK NOK OK SECUNDAIRE BUTANOL OK OK OK N BUTANOL OK OK OK TPM OK OK OK METHYLISOBUTYLKETON OK OK OK METHYL ETHYL KETON OK OK OK NMP OK OK OK TOLLUENE OK OK OK PM ACETATE OK OK OK 10% CITRIC ACID OK NOK OK 3% NAOH NOK NOK NOK 40% NAOH NOK NOK NOK 5% KOH NOK NOK NOK 25% KOH NOK NOK NOK NITRIC ACID CONCENTRATE OK NOK NOK PHOSPHORIC ACID CONCENTRATE OK NOK NOK FORMIC ACID CONCENTRATE OK OK OK MIBK OK OK OK ACETIC ACID CONCENTRATE OK NOK OK DIOXALANE OK OK OK SECUNDAIRY BUTANOL OK OK OK PROSOLV PM OK OK OK 27% CHLORIC ACID OK NOK NOK 20% ACETIC ACID OK OK NOK ETHANOL 99,9% DEP OK NOK OK ETHANOL 99,9% MEK OK OK OK NITRO OK NOK OK 25% OPTICAL 25 NOK NOK NOK ISOPAR C OK OK OK ISOPROPANOL OK OK OK METHANOL OK NOK OK ACETON OK OK OK HALF SYNTHETIC MATERIAL 10W40 OK OK NOK HEAVY DETERGENT NOK NOK NOK ANTIGEL CONCENTRATE / /58 OK OK OK POWER STEERING FLUID OK OK OK BRAKE FLUID OK NOK OK UNLEADED GASOLINE OK OK OK 1N SODIUM HYDROXIDE NOK NOK NOK DIESEL FUEL OK NOK OK WINDOW CLEANER CONCENTRATE 35/65=-18 C OK OK OK Minimum of 24 hours The chemical resistance test is a test in which we measure the contact angle (see ICT002) after the coated substrate was exposed to a chemical for the duration of 24 hours All coatings - watch glass dishes 2 % neutral detergent 100 % neutral detergent 2% base detergent (contains NaOH) (optical 25) sat. base detergent (contains NaOH) (optical 25) 2% acid detergent (contains 30 % H3PO4) (optical 30) 100 % acid detergent (contains 30 % H3PO4) (optical 30) denaturated ethanol methanol - isopropanol - diacetonalcohol 1-methoxy-2-propanol sec. Butanol N. butanol aceton methyl ethyl keton methyl isobutyl keton TPM NMP toluene ethylacetate PM acetate 20 % acetic acid acetic acid glacial 20 % HCl conc. HCl conc. H3PO4 conc. Formic acid 10 % HF 5 % NH4HF2 25 % H2SO4 10 % citric acid 5 % NaOH 25 % NaOH 5 % KOH 25 % KOH 5 % NH4OH 25 % NH4OH gasoline isopar C Demineralised water 6. Test procedure Put a drop of a chemical for 24 hours onto a coating. Place a watch glass dish over the spot. After the 24 hours, remove the watch glass dish and wash the chemical off with demineralised water and use a cloth to dry the substrate, when dry measure the contact angle (see ICT002). When the contact angle is below 85, the coating has no resistance to that specific chemical. The results are shown in a table which contains a range of chemicals and resistance or no resistance for that specific chemical. The more chemicals a coating resists, the better his chemical resistance.

4 Sliding angle Goldseal Glass Coating Spray on tempered glass/ contact angle 106 Goldseal Glass Coating Aërosol on tempered glass/ contact angle 108,8 Competitor 1 on tempered glass/ contact angle 97,8 Competitor 2 on tempered glass/ contact angle 100,9 sliding angle, measured according the Laplace-Young method( ) µl 40 µl 30 µl 20 µl 10 µl size of the drop expressed in microliter The sliding angle is a figure that gives us a view of the smoothness of the surface of a coating. The lower the sliding angle, the higher the smoothness. The sliding angle will be performed by using a tilting base. We start from a horizontal base (=0 ) and ends with a vertical base (=90 ). The base will be heightened with an accuracy of 0.1. In this test we place droplets of demineralised water on the surface. The droplets have a volume from 10 µl to 50 µl. After that we put a droplet on the surface we heighten the angle and look at the droplet till it drops off. The point where the droplet drops is called the sliding angle. The result of this test will be expressed in X degrees with Y volume of water. These two results are placed in a scatter (volume in function of the sliding angle).

5 Wear resistance Comparison of wear resistance results of Goldseal Glass Coating spray gun,gold Seal Glass Coating Aërosol, Competitor 1 and Competitor 2 number of cycles washability till contact angle is below GoldSeal GoldSeal Competitor 1 Competitor 2 Spray Aërosol N.A. This test will be used to determinate the abrasion resistance (life) of a coating on a substrate. (method was adapted for automotive industry) All coatings applied on glass (dimensions : 8 * 40 cm) - Braive instruments washability apparatus - Fixing holder ISO (with Velcro from 3M) and a total load of 454g Demineralised water, Vileda abrasive medium, Isopropanol P.A. 6. Test procedure The determinating parameter in this test is the contact angle. The values of the contact angle are put in a diagram (contact angle in function of the number of cycles of washability). The lowest limit for the contact angle is 85. The glass samples must be cleaned with isopropanol and blow dry. The contact angle must be known before the beginning of the test. Measuring the contact angle after running the washability test has always to be done with the profile of the drop seen from 90 on the direction of the washability movement. After measuring the initial contact angle: place the sample(s), with the coated side up, on the apparatus and make sure that the samples are positioned in the middle of a working station of the apparatus. Fix the samples and place the load (454g) with the vileda medium in the special designed holder on the samples (vileda medium positioned on the glass). Make sure that the water supply is 1 droplet of demineralised water for every stroke of a cycle. Set the number of cycles and press on the start button. After these cycles, measure the contact angle. Due to the return motion of the vileda medium left and right of the substrate, we will only measure contact angle between 10 and 16 cm measured from the left. If the contact angle is higher than 85 set again a number of cycles. Repeat this until contact angle is below 85, decreasing the amount of cycles as you get close to 85 Other parameters as described on refereed norms are not measured (relative scrub resistance R). Parameters that have been adapted to this test. - scrub media : vileda abrasive medium, brushes or flannel - scrub liquid : demineralised water in stead of special scrub liquid The determinating parameter is the contact angle. A hydrophobic glass coating fails when the contact angle drops under 85. The best abrasion resistance is when a glass coating has a lot of cycles of washability till his contact angle reaches 85. By using this test we can relate a test at the laboratory and a test at the field. At the field, people have do deal with wipers, sand and water