GB/T 5211.20-1999 Comparative colorimetric method for the colors of white, black and coloring pigments in the true color system
Some standard content:
GB/T5211.20---1999
This standard is formulated based on the international standard ISO787-25:1993 "General test methods for pigments and extenders - Part 25: Comparison of the colors of white, black and coloring pigments in the original color system - Colorimetric method". This standard is equivalent to ISO787-25:1993, the difference is that: in view of the situation in my country, glycerol is used instead of trimethylolpropane in the composition of alkyd resin. The recommended amount of test paint in Tables 1 and 2 in Article 5.3 is changed from the original volume (mL) to mass (g), which is conducive to accurate operation.
Another method for comparing pigment colors GB/T1864-1989 "Comparison of pigment colors" stipulates that the color of pigments should be compared by visual method. Since it may introduce certain subjective factors, it is more desirable to use colorimetry to compare colors whenever possible. This standard was proposed by the former Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Paints and Materials. This standard was drafted by: Changzhou Paint Chemical Research Institute, Ministry of Chemical Industry. This standard was drafted by: Shanghai Zhongnan Building Materials Company, Xiangfan Paint Factory, Shanghai Coking Co., Ltd. Titanium Dioxide Factory, Shanghai Chrome Yellow Pigment Factory, Shandong Longkou Taihang Pigment Company, Shenzhen Huafeng Chemical Co., Ltd., Shanghai Modern Engineering Research Institute. The main drafters of this standard are: Wu Liangjun, Zheng Wenjuan. 1226
GB/T 5211.20-1999
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standardization bodies (ISO member bodies). The development of international standards is generally carried out through ISO technical committees. Each member body interested in a professional field for which a technical committee has been established has the right to participate in the committee. International organizations, both governmental and non-governmental, in contact with ISO may also participate in the professional work. ISO works closely with the International Electrotechnical Commission (IEC) on electrotechnical standardization. The draft international standard accepted by the technical committee should be sent to each member group for voting. At least 75% of the voting member groups must agree before it can be published as an international standard. International standard ISO787-25 was developed by ISO/TC35 Paints and Varnishes Technical Committee, SC2 Pigments and Extenders Technical Committee.
ISO 787 consists of the following parts under the general title "General test methods for pigments and extenders": Part 1: Comparison of pigment colours
Part 2: Determination of volatile matter at 105 °C Part 3: Determination of water-soluble matter - Hot extraction method Part 4: Determination of pH of aqueous extracts Part 5: Determination of oil absorption
Part 7: Determination of sieve residue - Water method - Manual operation Part 8: Determination of water-soluble matter - Cold extraction method Part 9: Determination of pH value of aqueous suspensions
Part 10: Determination of density - Pycnometer method Part 11: Determination of fill volume and apparent density after filling Part 13: Determination of water-soluble sulphates, chlorides and nitrates Part 14: Determination of resistivity of aqueous extracts Part 15: Colouring pigments of the same type Comparison of lightfastness Part 16: Comparison of relative tinting strength (or equivalent tinting value) and dilute colour of coloured pigments - Visual comparison method Part 17: Comparison of tinting power of white pigments Part 18: Determination of sieve residue - Mechanical washing method Part 19: Determination of water-soluble nitrates (salicylic acid method) Part 21: Comparison of thermal stability of pigments using oven-dried paints Part 22: Comparison of resistance to bleeding of pigments Part 23: Determination of density (using centrifuge to remove entrained air) Part 24: Determination of relative tinting strength of coloured pigments and relative scattering power of white pigments - Photometric method Part 25: Comparison of colour of white, black and coloured pigments in true colour systems - Colorimetric method Part 26: Determination of relative tinting strength and residual dilute colour difference - Colorimetric method Parts 13, 14 and 17 are bound together as one text. Parts 6, 12 and 20 have been withdrawn. Part 26 is under preparation.
1 Scope
National Standard of the People's Republic of China
Comparison of the colour, in full-shade systems, ofwhite,black and coloured pigments -- Colorimetric methodGB/T 5211.20-1999
eqv ISO 787-25:1993
This standard specifies a general test method for the colour determination of white, black and coloured pigments in full-shade systems by colourimetric method in comparison with agreed reference pigments.
Note: When this general method is applicable to a specified pigment, a reference to this method shall be included in the product standard of the pigment, with details of any changes required due to the characteristics of the product. Only when this general method is not applicable to a particular product should a different photometric method for comparing the shades be specified. 2 Reference Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB92851988 Sampling of raw materials for paints and varnishes (eqvISO842:1984) GB/T11186.1—1989 Method for measurement of coating color Part One Principle (eqvISO7724-1:1984) GB/T11186.2—1989 Method for measurement of coating color Part 2 Color measurement (eqvISO7724-2:1984) GB/T11186.3-1989 Method for measurement of coating color Part 3 Calculation of color difference (eqvISO7724-3:1984) 2 Determination of relative tinting strength of coloring pigments and relative scattering power of white pigments - Photometric method GB/T13451.2—1992
(eqv ISO 787-24:1985)
3 Definitions
This standard adopts the following definitions.
3.1 Full-shade system A pigment system containing only one pigment. 3.2 Full-shade colour The colour of a full-shade system when applied as a covering layer (optically infinite) (see also Note 1 in 3.3). Note: Some highly transparent pigments cannot achieve covering. 3.3 Mass tone
The colour of a full-shade system when not applied as a covering layer, e.g. applied to a white test substrate. Note
1 The definition of mass tone here is different from the mass color (also called mass-tone and overtone) in ASTM D16, ASTM D 387 and D 3022 of the United States. The definition of mass color in ASTM D16 is similar to the colour of full-shade in 3.2. 2 For a shading system, some different mass tones may be produced due to the thickness of the applied layer and the nature of the test substrate. Therefore, the main color will only be clearly determined when the composition, preparation method, construction technology, film thickness and test substrate of the color system are specified. Approved by the State Administration of Quality and Technical Supervision on September 16, 1999 1228
2000-06-01 implementation
4 Principle
GB/T 5211.20-1999
The test pigment and the agreed reference pigment are dispersed in a specific test paint composed of alkyd resin and fumed silica using a flat grinder. The two dispersions are used to prepare a sample on a suitable substrate. The three stimulus values of the sample are measured according to GB/T11186.2, and the corresponding color characteristics (relative hue, chromaticity difference and lightness difference of black and white pigments; total color difference and lightness difference, hue difference, chroma difference) of the color pigment are calculated according to GB/T11186.3. 5 Materials
5.1 Alkyd resin (paint base)
Alkyd resin should contain 63% (m/m) linseed oil, 23% (m/m) phthalic anhydride and 14% (m/m) glycerol, and should meet the following requirements:
Not more than 15mgKOH/g
(7～10)Pa·s
(30～~50)mgKOH/g
5.2 Fumed silica
Fumed silica should meet the following requirements:Specific surface area (BET) (175～225)m2/g4% pH value of aqueous dispersion 3.6～4.5
Note: Fumed silica is necessary to avoid flocculation and control the fluidity of the material system. 5.3 Preparation of test paint
The recommended test paint (amounts shown in Tables 1 and 2) is prepared as follows: 97 parts (by mass) of alkyd resin (5.1) and 3 parts (by mass) of fumed silica (5.2) are mixed thoroughly, making sure that the silica is not lost due to dust escape. The mixture is dispersed twice on a three-roll mill or other dispersing equipment. Other test paints may also be used by agreement between the parties concerned, but this should be stated in the test report. Table 1 Recommended amount of white pigment and test paint Pigment (density, g/mL)
Titanium dioxide (p=4.0)
Zinc sulfide (p=4.0)
Zinc oxide (zinc white) (p=5.8)
Pigment type
(see 8.1.2)
6 Instruments
Pigment mass
Mass of test paint (5.3) 2)
Table 2 Recommended amount of coloring and black pigment and test paint Pigment mass
Ordinary laboratory instruments and glassware, and the following instruments: 6.1 Photometer
Instructions for use:
1) 14% (m/m) trimethylolpropane is specified in the international standard ISO787-25. 2) Volume (mL) is specified in the international standard ISO787-25. Quality of the test paint (5.3) 2)
6.1.1 For coloring and white pigments
GB/T5211.20—1999
Use the spectrophotometer or tristimulus colorimeter specified in GB/T11186.2. 6.1.2 For black pigments
Use the spectrophotometer or tristimulus colorimeter specified in GB/T11186.2 and meet the following requirements: a) Accuracy
The reflectance value provided by the spectrophotometer shall be accurate to 5 decimal places; the tristimulus value provided by the tristimulus colorimeter shall be accurate to 3 decimal places.
b) Calibration and zero adjustment
The instrument should preferably be adjusted using a suitable black standard so that the tristimulus value data is close to zero. If direct adjustment is not possible, the tristimulus readings of the black standard shall be subtracted from the tristimulus measurements of the reference and test panels. The black standard used for zero adjustment shall be a high-efficiency light trap, as shown in Figure 1, and shall have the following dimensions: A greater than or equal to the diameter of the instrument sample port + 5 mm; B greater than or equal to 80 mm; bzxZ.net
C greater than or equal to 70 mm.
The black standard shall have a matte black interior and a black velvet covering on the bottom. C
Figure 1 Black Standard
c) Standard Deviation of Tristimulus Values
For continuous determination of tristimulus values, the standard deviation a. shall be less than 0.005. This standard deviation is calculated from 20 tristimulus values measured without changing the test position for a specimen having a tristimulus value Y of approximately 0.5. 6.2 The minimum size of the substrate shall be 150 mm × 50 mm, uniform, non-fluorescent, compatible with the paint base used, and compatible with the color comparison method.
Steel plates, black and white contrast cards, painted cardboard, aluminized cards, standard art paper, or glass slides may be used. If glass slides are used, they shall be transparent, colorless, and of the same thickness for both the reference and test specimens. 6.3 The paint film preparation apparatus applies the color pastes of the test pigment and the agreed reference pigment to the substrate. 6.4 Wax paper cards are used to cover the wet sample during measurement, with a thickness of about 0.5 mm and a circular hole with a diameter slightly larger than the sample port of the spectrophotometer or tristimulus colorimeter (6.1); or glass slides of sufficient size to cover the sample, parallel to the plane, polished, colorless, and about 1 mm thick.
6.5 The flat grinder has a ground glass plate, preferably with water cooling. The glass plate shall have a diameter of (180~～250) mm and a known but selectable force of up to 1 kN shall be applied to the plate. The glass plate shall be operated at a speed of (70~120) r/min and the instrument shall be equipped with a device that can preset the number of revolutions to multiples of 25.
6.6 Knife Made of elastic steel or plastic sheet.
7 Sampling
GB/T 5211.20—1999
Take representative samples of the pigment to be tested according to GB9285. 8 Test procedure
Note that the results cannot be affected by the temperature rise during the grinding process. If the flat grinder does not have a water cooling device, be more careful. If there is any influence, a preliminary test should be carried out for verification. The new flat grinder glass plate should be pre-treated with pigment and an appropriate amount of paint base by grinding for 1000 revolutions under load. After grinding, the color paste is removed from the plate and discarded.
Before use, check the surface of each glass plate. It should have a flat, matte appearance and no scratches or glossy surfaces. 8.1 Test specimen
Weigh enough pigment so that when it is mixed with an appropriate amount of test paint (5.3), the resulting color paste can almost spread to the edge of the flat grinder. Weigh to an accuracy of 1 mg.
8.1.1 White Pigments
It is best to use the recommended amounts of pigment and test paint shown in Table 1 (see also Notes 1 and 2 to 8.1.2). 8.1.2 Colored and Black Pigments
The mass ratio of pigment to binder depends not only on the oil absorption of the pigment but also on the viscosity of the mixture during the grinding operation. First, all pigments can be roughly divided into one of the following three categories: Category a
Pigments with low binder requirements - pigment concentration of 65% (m/m); Category b
Pigments with medium binder requirements - pigment concentration of 40% (m/m); Category c
Pigments with high binder requirements - pigment concentration of 25% (m/m). In order to obtain approximately 2 mL of mixture in each case, it is best to use the recommended amounts for the corresponding category given in Table 2. If the selected pigment/binder mixture is found to be too thick or too thin when ground, the appropriate other ratio from Table 1 or Table 2 should be used. 1
2 If the diameter of the flat grinder glass plate is close to the maximum value specified in 6.5, it may be necessary to increase the specified amount in order to reduce the wear of the plate. 8.2 Preparation of pigment dispersion
Take appropriate amounts of the test paint and the agreed reference pigment (8.1.1 or 8.1.2). Place the test paint in the center of the lower glass plate of the flat grinder (6.5) and sprinkle the pigment on the paint. Use a spatula (6.6) to gently mix it into one. Distribute the color paste in several spots at a distance of 35 mm from the center of the bottom plate or spread it into a ring with an inner diameter of 40 mm and an outer diameter of 100 mm. Note: It is recommended to place a paper ring with a pattern that meets the requirements under the lower glass plate as a spreading pattern. Apply as much of the mixture on the spatula as possible to the upper glass plate of the flat grinder. Close the flat grinder glass plate and apply a maximum force of 1 kN or a force agreed upon by the parties concerned, grinding the mixture at 50 revolutions each time. After each grinding, collect the color paste from the two glass plates with a spatula and distribute the color paste on the bottom plate as described above and wipe the spatula on the upper plate as described above. After grinding all the required number of revolutions, remove the color paste and store it in a suitable container. Wipe the flat grinder and spatula clean. The total number of revolutions for grinding the mixture is the same as the number of revolutions required for the determination of dispersibility according to GB/T 13451.2 to ensure that the pigment is completely dispersed. This number of grinding revolutions should be stated in the test report. 8.3 Preparation of test panels
8.3.1 General
GB/T 5211. 20--1999
The preparation of test panels depends mainly on the application method, substrate and film thickness, which should be selected according to the specific application of the specific pigment coloring system.
Apply the test pigment dispersion and the agreed reference pigment dispersion in the same way to a film width of at least 40 mm. The wet sample should be measured as soon as possible after application.
8.3.2 White pigments
Apply the color paste to the substrate (6.2) using a film maker (6.3) with a gap of 150 μm to 200 μm (wet film thickness of about 75 μm to 100 μm) for titanium dioxide and zinc sulfide (100%) and 500 μm (wet film thickness of about 250 μm) for lead powder and zinc oxide (zinc white).
8.3.3 Colored pigments and black pigments
8.3.3.1 For the hiding layer for the evaluation of the color difference of the natural color, apply the test pigment dispersion and the agreed reference pigment dispersion as a hiding layer. NOTE: The coating is considered to be a hiding layer when the contrast is no longer visible when the film is visually examined on a black and white contrasting substrate. 8.3.3.2 For non-hiding layers to evaluate the primary color difference, apply the test pigment dispersion and the agreed reference pigment dispersion side by side in the same scraping process (if possible) and scrape the same film thickness. 8.4 Measurement
According to GB/T11186.2, use appropriate geometric conditions (see GB/T11186.1 and GB/T11186.3) Determine the tristimulus values of the panels made from the test material dispersion and the agreed reference pigment dispersion. The purpose of this standard is to test a variety of pigments, therefore, differences in the surface reflectance of the panels to be compared must not be allowed to affect the results. Except for very dark (dark) panels, this can be achieved by using 8/d or d/8 geometry conditions that include specular reflection. For high-gloss panels, subtract the surface reflectance value from the measured value to enable a better comparison with the visual assessment. 45/0 or 0/45 geometry conditions can only be used for high-gloss or completely matte panels. For very dark (dark) panels (such as panels made from carbon black or in the case of transparent pigment mass colors), it should be noted that differences in gloss or surface texture do not affect the reflectance value. In some cases, it is best to apply the dispersion to a glass plate, use 45/0 or d/8 geometry conditions that remove specular reflection, and measure through the glass plate. 9 Expression of results
From the measured tristimulus values, use the formula listed in GB/T11186.3 to obtain the color characteristics shown in 9.1 and 9.2 or 9.3 respectively. 9.1 White pigment and black pigment
9.1.1 Relative hue
Calculate the following values:
Aa\ - ai -- aR
b\ bi br
Where: R—refers to the agreed reference sample,
refers to the test sample.
The relative hue is determined by the positive and negative signs of Aa and Ab\ and the I△b\/△αI value (the absolute value of the ratio of the two). Obtain the corresponding hue from Table 3 to express the relative hue.
Table 3 Names of relative hues
Signs
Yellow-green (YG)
Green (G)
Signs of Aa
Yellow-red (YR)
Red (R)
[Ab\/Aa\
Signs of Ah'
9.1.2 Quantity of chromaticity difference
GB/T 5211. 20—1999
Table 3 (End)
Signs of Aa\
Blue-green (BG)
Blue (B)
The chromaticity difference is expressed by the △s value, which is calculated as follows: Blue-red (BR)
As = ()2+ (b)2
As value can also be calculated by the following formula:
As = V(AES)2 - (AL*)2
9.2 Lightness difference
Lightness difference is calculated by the following formula:
AL* - Li LR
Wherein: R
refers to the agreed reference sample;
T-refers to the test sample.
9.3 Coloring pigments
IA/Aa\
The color difference is expressed according to the CIE1976L\a\b color difference AE%, and the lightness difference AL:, hue difference AHi and chroma difference AC% (see GB/T 11186.3) should also be indicated.
10 Test report
The test report shall include at least the following information: a) type and name of the test product and agreed reference pigment; b) indication of reference to this national standard;
c) composition of the grind (see 8.1);
d) method of preparation of the test specimens;
e) if a flat grinder is used, the selected grinding speed; f) if possible, the paint film thickness, pigment concentration and substrate; g) indication of whether it is the natural color or the main color;
h) type of colorimeter (spectrophotometer or tri-stimulus colorimeter) and the geometric conditions used for measurement; i) test results expressed in accordance with Chapter 9;
j) any deviation from the specified test method, k) test date.
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