GB/T 5211.17-1988 Comparison of white pigment contrast ratio (hiding power)

GB/T 5211.17-1988 Comparison of white pigment contrast ratio (hiding power) GB/T5211.17-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Comparison of contrast ratio (hiding power) of white pigments This standard refers to the international standard ISO2814-1973 "Paints and varnishes - (hiding power) comparison method".
Subject content and scope of application
UDC 667.622: 667
GB 5211.17-88
-Contrast ratio of paints of the same type and color This standard specifies a general test method for comparing the contrast ratio (hiding power) of similar white pigments. When this general method is not applicable to a specific product, a special method should be specified to compare the contrast ratio. 2 Reference Standards
GB9285 Sampling of Raw Materials for Paint and Varnish 3 Principle
Use the same paint to make paint slurry with the same formula and method for the sample and the standard sample, and use a rotary paint coater to make a coating film with basically the same thickness on the polyester film. Use a reflectivity meter to measure the reflectivity on the black background and the reflectivity on the white background, and divide the reflectivity on the black background by the reflectivity on the white background to obtain the contrast ratio. Compare the contrast ratios of the sample and the standard sample to evaluate their quality. Materials
4.1 Linseed oil modified glycerol alkyd resin: oil content 55%, content 50%. 4.2200 paint solvent oil.
4.3 Mixed drying agent of lead naphthenate, cobalt naphthenate, manganese naphthenate, zinc naphthenate, and calcium naphthenate. 5 Instruments
Paint mixer: The glass bottle loaded into the mixer oscillates 680 to 690 times per minute, with a distance of 16 mm and a swing angle of 30°. 5.1
Scraper fineness meter: 0～50μm.
Lever micrometer, range 0～25mm.
5.4 Glass plate: flat surface, length 130mm, width 100mm. 5.52 Polyester film: thickness 20～40μm, length 120mm, width 90mm. 5.6 Rotary paint coater: adjustable speed.
5.7 Reflectivity meter: accuracy within 1%.
6 Sampling
Take representative samples of the test pigments according to the provisions of GB9285. 7
Test steps
All tests should be carried out at a temperature of 23±2℃ and a relative humidity of (50±5)%. 7.1 Preparation of paint paste
Approved by the Ministry of Chemical Industry of the People's Republic of China on August 1, 1988, and implemented by the Ministry of Industry and Information Technology on April 1, 1989
GB 5211.17-88
Put 100g of glass beads in the glass bottle (5.1) of the paint mixer, weigh 12g of the sample and put it in the bottle, then add 37g of alkyd resin (4.1), and add appropriate amount of No. 200 paint solvent oil as needed. Put the glass bottle containing the material in the base hole of the paint mixer, start the mixer to vibrate, and check with a scraper gyrometer (5.2). When the grinding fineness is less than 20um, add appropriate amount of mixed catalyst (4.3), stir well and set aside.
7.2 Preparation of coating film
Measure the thickness of the polyester film with the lever-down scale (5.3) and measure at four points on the top and bottom. Add a few drops of ethanol to the whole glass plate (5.4), and then place the polyester film (5.5) on it. There should be no bubbles under the film. Fix the glass plate in the center of the rotary paint coater (5.6), add 5g of the paint slurry in the center of the glass plate, rotate it at a selected stable speed for 30s to form a uniform coating film, change the speed, and then make another coating film. Make two coating films for each speed. 7.3 Drying of coating film
Put the glass plate with the coating film (7.2) horizontally for drying. The drying time should be at least 48h, but not more than 168h. 7.4 Determination of film thickness
Remove the coating film from the glass plate and measure the thickness at the four points on the left and right of the bottom with the lever-down scale (5.3) to calculate the half-mean thickness of the coating film. 7.5 Reflectivity Determination
Cover the dried coating on the white porcelain plate attached to the reflectivity meter (5.7), add a few drops of ethanol between the coating and the porcelain plate, remove air, and make optical contact. Use the reflectivity meter to measure the reflectivity of 4 points on the upper and lower sides, and calculate the half-mean. Then cover the coating with a black porcelain plate, measure it in the same way, and calculate its average value. The standard sample is also painted and filmed according to the test steps in Chapter 7, and its average reflectivity is calculated. 8. Expression of resultsWww.bzxZ.net
The contrast ratio (hiding power) of each coating is calculated according to the following formula and expressed as a white fraction: Contrast ratio (hiding power)
Formula: R-reflectivity of the coating on the black background;
-reflectivity of the coating on the black background.
RB— ×100
Calculate the average contrast ratio of two coatings with basically the same thickness (the average thickness difference does not exceed 2μm), and compare it with the average contrast ratio of the standard sample with basically the same thickness to evaluate its quality. 9 Test report
The test report should at least include the following contents; a.
Type and name of the test pigment sample and standard sample: the fineness of the obtained paint slurry, μm
The thickness of the coating film for comparison contrast ratio, μm, c.
d. : The average contrast ratio of the test sample and the standard sample, e.
The difference from the test steps mentioned above after consultation, f.
Test printing date.
Additional remarks:
This standard is under the jurisdiction of the Technical Committee for Standardization of All-solid Coatings and Pigments. This standard was drafted by the Institute of Materials Industry of the Ministry of Chemical Industry. The main drafters of this standard are Zhu Yang and Zhang Xiuyun. 1219
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