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GB 24409-2020 (GB24409-2020) PDF English
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GB 24409-2020: PDF in English

GB 24409-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
G 51
Replacing GB 24409-2009
Limit of Harmful Substances of Vehicle Coatings
ISSUED ON: MARCH 4, 2020
IMPLEMENTED ON: DECEMBER 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative References ... 5 
3 Terms and Definitions ... 6 
4 Product Classification ... 10 
5 Requirements ... 10 
6 Test Methods ... 16 
7 Inspection Rules ... 18 
8 Packaging Marks ... 19 
9 Implementation of Standard ... 19 
Appendix A (normative) Determination of Moisture Content - Gas
Chromatography ... 20 
Appendix B (normative) Determination of Hexavalent Chromium (Cr6+) Content
- Spectrophotometry ... 24 
Bibliography ... 31 
Limit of Harmful Substances of Vehicle Coatings
1 Scope
This Standard stipulates the product classification, requirements, test methods,
inspection rules, packaging marks and implementation of the Standard related to the
allowable limits of substances harmful to humans and the environment in various types
of vehicle coatings.
This Standard is applicable to various kinds of original vehicle coatings, refinish
coatings, rail transit vehicle coatings, motorcycle (including electric motorcycle)
coatings, bicycle (including electric bicycle) coatings, and coatings for other vehicles
(special motor vehicles, low-speed vehicles and trailers) and vehicle parts.
This Standard is not applicable to coatings for tractor transport units, special wheeled
mechanical vehicles and military vehicles.
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 1725-2007 Paints, Varnishes and Plastics - Determination of Non-volatile-matter
Content
GB/T 3186 Paints, Varnishes and Raw Materials for Paints and Varnishes - Sampling
GB/T 6682-2008 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 6750-2007 Paints and Varnishes - Determination of Density - Pycnometer
Method
GB/T 8170-2008 Rules of Rounding off for Numerical Values & Expression and
Judgement of Limiting Values
GB/T 9750 Marks for Package of Coating Products
GB/T 9754-2007 Paints and Varnishes - Determination of Specular Gloss of Non-
metallic Paint Films at 20°, 60° and 85°
GB/T 9758.5-1988 Paints and Varnishes - Determination of Soluble Metal Content -
Part 5: Determination of Hexavalent Chromium Content of the Pigment Portion of the
Liquid Paint or the Paint in Powder Form - Diphenylcarbazide Spectrophotometric
Method
GB/T 9760-1988 Paints and Varnishes - Preparation of Acid Extracts from Paints in
Liquid or Powder Form
GB/T 23986-2009 Paints and Varnishes - Determination of Volatile Organic Compound
(VOC) Content - Difference Method
GB/T 23990-2009 Determination of the Contents of Benzene Toluene Ethylbenzene
and Xylene in Coatings by Gas Chromatography
GB/T 23992-2009 Determination of Chlor-hydrocarbon Content in Coatings - Gas
Chromatographic Method
GB/T 30647-2014 Determination of Harmful Elements Total Content of Coatings
GB/T 34675-2017 Determination of Volatile Organic Compound (VOC) Content in
Radiation Curable Coatings
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 Road Vehicle
Road vehicle refers to vehicles that are designed and manufactured to carry
passengers, transport goods or perform special operations on the road, and are legally
allowed to travel on the road. Road vehicle includes motor vehicles and non-motor
vehicles.
[GA 802-2014, Definition 3.1]
3.2 Rail Transit Vehicle
Rail transit vehicle refers to a means of transportation that needs to travel on a specific
track. Rail transit vehicle includes powered car train-sets, passenger cars (railway
vehicle), urban rail transit vehicles and wagons, etc.
3.3 Power-driven Vehicle
Power-driven vehicle refers to a wheeled vehicle that is driven or towed by a power
device, and travels on the road to carry passengers or transport goods, and for special
engineering operations. Power-driven vehicle includes cars, car trains, motorcycles,
tractor transport units, special wheeled mechanical vehicles and trailers.
transportation tool that is, in principle, grouped to be used in passenger trains and
freight trains.
[GB/T 4549.1-2004, Definition 2.1]
3.9 Carriage; Passenger Car; Coach
Railway Vehicle
Carriage (railway vehicle) refers to a vehicle used to transport passengers and operate
for this service, or, in principle, grouped to be used in passenger trains.
[GB/T 4549.1-2004, Definition 2.2]
3.10 Urban Rail Transit Vehicle
Urban rail transit vehicle refers to a public transport mode with the vehicle
transportation system that adopts a track structure for load-bearing and guidance; in
accordance with the requirements of the overall planning of urban transportation, it
sets up fully enclosed or partially enclosed exclusive track lines, and transports a large-
scale passenger flow in the form of trains or single vehicles. Urban rail transit vehicle
includes subway system, light rail system, monorail system, tram car, maglev system,
automatic guide rail system and city rapid rail system.
3.11 Wagon; Freight Car
Wagon (freight car) refers to vehicle that is used to transport goods and serve for this
purpose, or in principle, grouped to be used in freight trains. By purpose, it can be
divided into general wagons and special-purpose wagons.
[GB/T 4549.1-2004, Definition 2.37]
3.12 Special Motor Vehicle
Special motor vehicle refers to vehicle that is equipped with special-purpose equipment
or appliances, and designed and manufactured to be used for special engineering
operations (including health and medical treatment), such as: truck cranes, fire trucks,
concrete pump trucks, wreckers, aerial work vehicles, road sweeping trucks, sewage
suction trucks, rig trucks, instrument trucks, inspection vehicles, monitoring vehicles,
power supply vehicles, communication vehicles, television vehicles, blood collection
vehicles, medical treatment vehicles and medical examination vehicles, etc. However,
it does not include vehicles equipped with special-purpose equipment or appliances,
and more than 9 seats (including the driver’s seat) (except fire trucks).
[GB 7258-2017, Definition 3.2.3]
3.13 Low-speed Vehicle
interference in a thin layer), with different colors (color change, color jump and color
shade change) or texture.
[GB/T 5206-2015, Definition 2.91]
3.22 High Decorative Coatings Including Effect Pigment
High decorative coatings including effect pigment refers to a type of coating that
contains effect pigment, and whose coated orange peel value in the medium long wave
is ≤ 15 and short wave is ≤ 25.
3.23 Volatile Organic Compound
VOC
Volatile organic compound refers to organic compound participating in atmospheric
photochemical reactions, or organic compound determined in accordance with
relevant regulations.
3.24 Volatile Organic Compound Content
VOC Content
Volatile organic compound content refers to the mass of volatile organic compounds in
the coating measured under specific conditions.
[GB/T 5206-2015, Definition 2.271]
3.25 Application Condition
Application condition refers to the condition where the application can be carried out
after all the components of a product are mixed, and when the application modes and
application conditions meet the requirements in the corresponding technical
specifications.
4 Product Classification
In this Standard, vehicle coating is divided into: water-based coating, solvent-based
coating, radiation-curing coating and powdered coating.
5 Requirements
5.1 Except for special functional coatings, the limit value of VOC content in the various
types of vehicle coatings shall comply with the requirements of Table 1, Table 2 and
Table 3.
NOTE: special functional coatings refer to primers for polypropylene substrates (including
accordance with a method determined through negotiation. The sampling size shall be
determined in accordance with the demand of inspection.
6.2 Test Methods
6.2.1 VOC content
6.2.1.1 Density
In accordance with the stipulations of GB/T 6750-2007, conduct the test. The test
temperature is (23 ± 0.5) °C.
6.2.1.2 Gloss
In accordance with the stipulations of GB/T 9754-2007, conduct the test. Use a wet
film preparation device with a groove depth of (100 ± 2) μm to prepare a sample on
black glass or a flat glass plate pre-coated with matte black paint on the back. The
baking condition is (105 ± 2) °C/1h; use a 60° specular gloss meter for the test.
6.2.1.3 VOC content in water-based coatings
Firstly, in accordance with the stipulations of Appendix A, determine the moisture
content in water-based coatings.
If the moisture content in the coatings is greater than or equal to 70% (mass fraction),
then, proceed in accordance with the stipulations of GB/T 23986-2009. Weigh-take
around 1 g of sample. The chromatographic column shall adopt a medium-polarity
chromatographic column (6% cyanopropylphenyl / 94% polydimethylsiloxane capillary
column). The label is diethyl adipate. VOC content shall be calculated in accordance
with 10.4 in GB/T 23986-2009.
If the moisture content in the coatings is less than 70% (mass fraction), then, proceed
in accordance with the stipulations of GB/T 23985-2009. Non-volatile-matter content
shall be determined in accordance with the stipulations of GB/T 1725-2007. Weigh-
take around 1 g of sample. The baking condition is (105 ± 2) °C/1h. VOC content shall
be calculated in accordance with 8.4 in GB/T 23985-2009.
6.2.1.4 VOC content in solvent-based coatings
In accordance with the stipulations of GB/T 23985-2009, conduct the test. Non-volatile-
matter content shall be determined in accordance with the stipulations of GB/T 1725-
2007. Weigh-take around 1 g of sample. The baking condition is (105 ± 2) °C/1h. Do
not determine the moisture content. The moisture content shall be set to zero.
The calculation of VOC content shall be conducted in accordance with 8.3 in GB/T
23985-2009.
6.2.1.5 VOC content in radiation-curing coatings
7.1.1 Under normal production, type inspection shall be conducted at least once a year.
Type inspection items include all the requirements listed in this Standard.
7.1.2 Under one of the following circumstances, type inspection shall be conducted at
any time:
---When new product is initially finalized;
---When product is produced off-site;
---When there are significant changes in the production formula, process, the
source of key raw materials and application ratio under the application condition;
---When production is resumed after 3 months of suspension.
7.2 Determination of Inspection Result
7.2.1 The determination of the inspection result shall be conducted in accordance with
the rounding-off comparison method in GB/T 8170-2008.
7.2.2 When reporting the inspection result, the application ratio under the expressly
indicated application condition shall be simultaneously indicated.
7.2.3 When the inspection results of all items meet the requirements of this Standard,
then the products comply with the requirements of this Standard.
8 Packaging Marks
8.1 The packaging marks shall comply with the stipulations of GB/T 9750. In addition,
products that pass the inspection in accordance with this Standard may be expressly
indicated on the packaging marks.
8.2 The packaging marks or product specification shall expressly indicate the
application ratio under the application condition.
8.3 The packaging marks or product specification shall indicate the classification,
category and type (or application mode) of products that comply with this Standard.
8.4 For polyurethane, epoxy and other multi-component cured coatings, the period of
application shall be indicated on the packaging marks or in the product specification.
9 Implementation of Standard
When conducting spot-check of the coating products under the application condition
on the site of coating, the sampling inspection of multi-component cured coatings, such
as polyurethanes and epoxy resins, shall be conducted within the period of application.
A.3.1 Chromatographic column: capillary column of styrene-divinylbenzene porous
polymer, 25 m  0.53 mm  10 μm.
A.3.2 Inlet temperature: 250 °C.
A.3.3 Detector temperature: 300 °C.
A.3.4 Split ratio: 5:1.
A.3.5 Column temperature: programmed temperature-raising, 100 °C, maintain for 2
min, then, at 20 °C/min, raise the temperature to 130 °C and maintain for 3 min; at
30 °C/min, raise the temperature to 200 °C and maintain for 5 min.
A.3.6 Carrier gas: hydrogen, flow rate: 6.5 mL/min.
NOTE: in accordance with the performance of the used gas chromatograph, the type of
the chromatographic column and the actual condition of the sample to be tested,
optimal gas chromatography test conditions may also be selected.
A.4 Test Procedures
A.4.1 Test the relative response factor (R) of water
In the same sample preparation bottle (A.2.4), weigh-take around 0.2 g of distilled
water (A.1.1) and around 0.2 g of the internal standard substance (A.1.3), accurate to
0.1 mg. Record the mass of water mw and the mass of the internal standard substance
mi, then, add 5 mL of dilution solvent (A.1.2); seal the sample preparation bottle (A.2.4)
and shake it well. Use a micro-syringe (A.2.3) to draw 1 μL of the mixture in the sample
preparation bottle (A.2.4); inject it into the chromatograph, record the chromatogram.
In accordance with Formula (A.1), calculate the relative response factor (R) of water:
Where,
R---relative response factor of water;
mi---mass of internal standard substance, expressed in (g);
Aw---peak area of water;
mw---mass of water, expressed in (g);
Ai---peak area of internal standard substance.
If the internal standard substance and the dilution solvent are not anhydrous reagents,
then, use the same amount of internal standard substance and dilution solvent (mixed
Appendix B
(normative)
Determination of Hexavalent Chromium (Cr6+) Content -
Spectrophotometry
Warning -- the use of all samples and reagents that potentially contain
hexavalent chromium (Cr6+) in the test method shall be prevented with
appropriate measures. Solutions and waste materials containing hexavalent
chromium (Cr6+) shall be properly handled.
B.1 Principle
If the total chromium content in the sample is less than 8 mg/kg, then, the result of
hexavalent chromium (Cr6+) content shall be reported as “not detected”; the detection
limit is 8 mg/kg. If the total chromium content in the sample is ≥ 8 mg/kg, then, after
the sample (simultaneously spiked with the matrix) is dispersed by ultrasound, use an
alkaline digestion solution to extract hexavalent chromium (Cr6+) compound from the
sample. The hexavalent chromium (Cr6+) in the extraction solution reacts with
diphenylcarbazide in an acidic solution to generate a purple complex. Use
spectrophotometry to determine the hexavalent chromium (Cr6+) content in the test
solution (wavelength at 540 nm); meanwhile, determine the non-volatile-matter content
in the sample. The final result shall be reported as the hexavalent chromium (Cr6+)
content in the dry film.
B.2 Reagents and Materials
In the analytical tests, reagents that are confirmed to be analytically pure shall merely
be used; the used water shall comply with the requirements of Level-3 water in GB/T
6682-2008.
B.2.1 N-Methyl-pyrrolidone (NMP): the reagent shall be stored in a brown bottle at
20 °C ~ 25 °C; kept away from direct sunlight. Before use, add 10 g of active molecular
sieve to each 100 mL of reagent; store for more than 12 h. After the container is opened,
the storage period is 1 month.
B.2.2 Nitric acid: about 65% (mass fraction); density is about 1.40 g/mL; yellowed nitric
acid shall not be used.
B.2.3 Sulfuric acid: about 98% (mass fraction); density is about 1.84 g/mL.
B.2.4 Sodium hydroxide.
B.2.5 Sodium carbonate anhydrous.
may be added, so as to increase the wettability of the sample. Use a stopper to cover
the digestion device (B.3.5); place it in the ultrasonic water bath kettle (B.3.3); at 60 °C
~ 65 °C, conduct ultrasonic treatment for 1 h.
From the ultrasonic water bath kettle (B.3.3), take out the digestion device (B.3.5);
gradually cool it down to room temperature. Transfer the solution (do not filter the
solution, even if the solution is turbid, or there are flocculent precipitates) in the
digestion device (B.3.5) into a clean beaker (B.3.9). While stirring it, drop-wise add
nitric acid (B.2.11) into the beaker. Use an acidity meter (B.3.4) to test it; adjust the pH
value of the solution to 7.5 ± 0.5. Thus, obtain an extract. The extract shall develop
colors and be determined as soon as possible.
B.4.3 Tests
B.4.3.1 Preparation of color-developing solution
In the extract in each beaker (B.3.9), slowly drop-wise add sulfuric acid solution
(B.2.12). Use the acidity meter (B.3.4) to test it; adjust the pH value of the solution to
2.0 ± 0.5; evenly mix it. Then, use the transfer pipette (B.3.7) to accurately add 2.0 mL
of diphenylcarbazide color developer (B.2.15); mix it well. Then, transfer all of it to a
100 mL volumetric flask (B.3.6); use water to dilute to the scale to obtain the test
solution. Let the test solution settle for 5 min ~ 10 min, then, determine it as soon as
possible; complete the on-board test within 30 min.
B.4.3.2 Preparation of series of standard working solutions
Use the transfer pipette (B.3.7) to respectively transfer-take 0.0 mL, 2.0 mL, 4.0 mL,
6.0 mL, 8.0 mL, 10.0 mL and 20 mL of hexavalent chromium (Cr6+) standard solution
(B.2.17) to a 100 mL volumetric flask. Use the measuring cylinder (B.3.8) to
respectively add 50 mL of water; respectively drop-wise add sulfuric acid solution
(B.2.12). Use the acidity meter (B.3.4) to test it; adjust the pH value of the solution to
2.0 ± 0.5. Use the transfer pipette (B.3.7) to respectively add 2.0 mL of the color
developer (B.2.15); respectively use water to dilute to the scale; evenly mix it. Let it
settle for 5 min ~ 10 min, then, complete the determination as soon as possible within
30 min. The mass concentration of hexavalent chromium (Cr6+) in this series of
standard working solutions is respectively: 0.0 mg/L, 0.1 mg/L, 0.2 mg/L, 0.3 mg/L, 0.4
mg/L, 0.5 mg/L and 1.0 mg/L.
B.4.3.3 Determination of hexavalent chromium (Cr6+) content in sample
Respectively transfer an appropriate amount of the series of standard working
solutions into a 10 mm colorimetric cell. On a spectrophotometer (B.3.2), at a
wavelength of 540 nm, determine its absorbance. Use the absorbance value
corresponding to the mass concentration value to draw a calibration curve. The
correction coefficient of the calibration curve shall be ≥ 0.99. Otherwise, a new
calibration curve shall be re-drawn.
Where,
SR---spiked matrix recovery rate, expressed in (%);
SS---hexavalent chromium (Cr6+) content in spiked sample (calculated by dry film),
expressed in (mg/kg);
US---hexavalent chromium (Cr6+) content in un-spiked sample (calculated by dry film),
expressed in (mg/kg);
SA---hexavalent chromium (Cr6+) content in spiked solution converted into hexavalent
chromium (Cr6+) content calculated by dry film, expressed in (mg/kg).
Example: add 0.5 mL of hexavalent chromium (Cr6+) standard stock solution (200 mg/L);
the non-volatile-matter content in the sample is 0.50 g/g, and the weighed
sample mass is around 0.1 g; then, SA = 0.5 mL  (100 mg/L)/(0.1 g  0.50 g/g)
= 1,000 mg/kg.
In accordance with the hexavalent chromium (Cr6+) content in the sample being tested,
other appropriate amounts of spiked solution may be selected, so as to ensure that the
mass concentration of spiked solution is within the appropriate curve range.
B.4.4.3 Correction of results and detection limits
The acceptable range of the spiked matrix recovery rate shall be ≥ 50% and ≤ 125%.
When the spiked matrix recovery rate is < 50%, add a double amount of spiked solution
for the test. When the spiked matrix recovery rate is > 125%, add an equal amount of
spiked solution for the test. If the spiked matrix recovery rate in the re-test is still beyond
the range ≥ 50% and ≤ 125%, then, the alkaline digestion method is inapplicable to the
sample being tested. Then, the hexavalent chromium (Cr6+) content in the sample shall
be tested in this way: in accordance with Chapter 6, 8.1, 8.2.3 and 8.4 in GB/T 9760-
1988, prepare the acid extract (the weighed mass of the prepared pigment is around
0.5 g), then, in accordance with GB/T 9758.5-1988, test the hexavalent chromium (Cr6+)
content. The result is divided by the non-volatile-matter content, then, reported as the
hexavalent chromium (Cr6+) content in the dry film.
If the spiked matrix recovery rate is > 75% and ≤ 125%, then, it is no need to correct
the result; the detection limit is 8 mg/kg.
If the spiked matrix recovery rate is within the range ≥ 50% and ≤ 75%, in accordance
with the spiked matrix recovery rate, correct the result and the detection limit. In other
words: the result is multiplied by the ratio of 100% spiked recovery rate to the actual
spiked matrix recovery rate; the detection limit is corrected in the same way.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.