A test method for the integration of non-volatile objects in a coating

The number of non-volatile object integrals of the coating refers to the residuals left by the coating after curing or drying at a specified temperature and time as a percentage of the volume of the original liquid coating, also known as the volume solid content. Our general contact is more paint non-volatile mass score, its test method is simple and easy to do, so the application of more, but not volatile object integral number can more intuitively reflect the coating use of a coating, many foreign paint companies' product technical indicators are generally expressed is also not volatile object integral number. GB /T 9272-2007 specifies a method for testing the number of non-volatile object integrals of a coating, this test uses a metal disc as a lacquerer, the four sets of coatings for the determination of the number of non-volatile object integrals, the introduction of the paint non-volatile object integrals measurement method and the test process of the note
China
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1 Test Part
1.1 principle
determine the mass and volume of unpainted discs. The volume and mass of the dry film are calculated by the volume and mass of the dry film by the volume and mass before and after the coating of the tested coating, the volume and mass of the liquid coating is calculated by the non-volatile mass fraction and density of the liquid coating, the volume of the dry coating is divided by the volume of the liquid coating multiplied by the volume of the liquid coating multiplied by the volume of the non-volatile material in the liquid coating.
1.2 Instruments and
analysis balance: 0.1mg accuracy. Single-disc balance is more convenient, because to weigh the mass of objects in the liquid, so it is generally necessary to change the single-disc balance, with matching accessories instead of balance plate. There is currently an electronic balance with hooks at the bottom of the balance that make it easier to determine the mass of an object in a liquid.
oven: blowing thermostat oven, precision taxi 2 oC.
dryer: Put the desiccant inside.
metal discs (generally stainless steel or copper): about 60 mm in diameter, about 0.7 mm in thickness, with a small hole of 2 to 3 mm on the side.
: Nickel chrome wire with a diameter of no more than 0.3mm and a length of 30 to 40mm.
: 600m l or 1000m l beech, can be soaked in metal wafers and 10mm away from the liquid surface.
impregnation liquid: suitable density and type of liquid, requires not react with the coating or dissolve the coating and has good wetting, if necessary can be added moisturizer, distilled water suitable for most products.
: epoxy primer, epoxy thick slurry paint, aolic acid primer, aleate paint.
1.3 Test
1.3.1 Determination of the volume of unpainted wafers
place the discs and hooks in an oven at 105 s 2 oC for 10 minutes, cool them in a dryer, and weigh the mass of the discs in the air.
the disc completely immersed in the liquid, and the horizontal surface of the liquid exceeds 10mm above the top of the disc, weighing again. Pressing calculates the volume of the wafer V1 (m l):
: m1- mass of the unpainted disc in the air (g) and m2- mass of the unpainted wafer in the liquid (g); P1-the density of impregnated fluid (g /m l) at the test temperature.
1.3.2 Volume determination of painted discs
tie the discs to the wire, immerse them all in the inspected paint, and then put the discs up at a constant speed, drip dry and remove the thick edges formed at the bottom of the discs, dry the painted fillets according to the drying conditions expressed by the product, if no special instructions, generally baked for three hours at (105 taxi 2) oC. After drying, remove the painted fillets, place them together with the hooks in a dryer to cool, and weigh them in the air. Weighing the painted discs in the same liquid selected when the impregnable fillets should be the same temperature as when the unpainted fillets are weighed in the liquid and the depth of immersion is the same. Pressing calculates the volume of the painted disc V2 ( m l ):
: m3- the mass of the painted disc in the air ( g ) , and m4 - the mass of the painted disc in the liquid ( g ) ; P1- Density of impregnated fluid at test temperature (g/m l).
1.3.3 Determination of non-volatiles in liquid coatings
Determination of non-volatiles in liquid coatings is carried out in accordance with GB/T 1725-2007 "Measurement of non-volatile content of color paints, varnishes and plastics".
1.3.4 Determination of liquid coating density the density of
liquid coatings is carried out in accordance with GB /T 6750-2007 "Color paint and varnish density determination of specific gravity bottle method."
1.4 Calculation of results
volume V3 (m l), density p0 (g/m l) of dry coating, and non-volatile object integral NVv (%) using the following formula:
in the air: m1- the mass of the wafer in the air (g); m2- the mass of the unpainted wafer in the liquid (g); m3- the mass of the painted disc in the air (g); m4 - the mass of the painted disc in the liquid (g); V1 - volume of unpainted wafers (m l); V2- the volume of the painted disc (m l); NVm- Mass fraction (%) of non-volatiles in coatings; p1- at the test temperature, the density of the impregnated liquid (g/m l); p2- At the test temperature, the density of the liquid coating (g/m l).
according to the above method, distilled water is selected as a liquid immersed in metal discs, and the following four sets of coatings are determined by the number of integrals of non-volatile objects, the results of which are found in Table 1. Table
Table 1 The results of the measurement of the number of non-volatile object integrals of the coating
2 results and the discussion of
2.1 paint non-volatile mass fraction, non-volatile object integral number and dry film density relationship

2.2 The factors that should be noted in the test may affect the test results
(1) when dipping metal discs, can not be used weighing hooks, the coating should not be too thick, otherwise it is not easy to dry, but also easy to form bubbles, will make the test results too large. If the surface of the coating film has bubble formation, with the tip of the needle to puncture it, generally requires drying to get a 30 to 60.m thick uniform coating, if a dip can not reach this thickness, can be immersed many times; If the coating obtained by one immersion is too thick, it can be diluted slightly with a suitable thinner and then dipped.
(2) When dipping a metal disc into a liquid weighing, ensure consistent depth before and after immersion, avoid different buoyant effects on the hook test results, the temperature of the impregnated liquid should be consistent during the test process, to avoid the effect of the change in the density of the impregnated liquid on the test results. If the quality changes rapidly due to the absorption of liquid by the paint film, an alternative liquid that is not absorbed by the paint film should be replaced and re-determined.
(3) Non-volatile mass fractions can also be calculated using the quality of unpainted wafers and the quality before and after coating fillets are dried, but it should be ensured that there will be no paint drops during the drying process, otherwise the test results will be small.
2.3 The relationship between the method and the theoretical value and the scope of application
The amount of integration of non-volatile objects in the coating measured by this method may be greater than, equal to or less than the combined volume of the theoretical individual components, which is related to the solubility characteristics of the resin and solvent, the reaction curing properties and the degree to which the base material wets the pigment. When the pigment volume concentration is greater than the critical pigment volume concentration, because the number of substitums is not enough to wet all pigment mass points, so pigment mass is loose in the coating film, it is not appropriate to use this method for testing.