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GB/T 1731-2020 English PDF (GBT1731-2020)

GB/T 1731-2020 English PDF (GBT1731-2020)

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GB/T 1731-2020: Determination of flexibility of coating and putty films

This Standard specifies the determination of flexibility of coating and putty films by a flexibility tester. Use the smallest spindle diameter that does not cause damage to the coating and putty films to represent the flexibility of the coating and putty films. This Standard applies to the determination of flexibility of coating and putty films.
GB/T 1731-2020
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 87.040
G 50
Replacing GB/T 1731-1993, GB/T 1748-1979
Determination of flexibility of coating and putty films
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: OCTOBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Determination of flexibility of coating films ... 6
5 Determination of flexibility of putty films ... 9
6 Test report ... 11
Determination of flexibility of coating and putty films
1 Scope
This Standard specifies the determination of flexibility of coating and putty films by a flexibility tester. Use the smallest spindle diameter that does not cause damage to the coating and putty films to represent the flexibility of the coating and putty films.
This Standard applies to the determination of flexibility of coating and putty films. 2 Normative references
The following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 3186, Paints, varnishes and raw materials for paints and varnishes - Sampling
GB/T 9271, Paints and varnishes standard panels for testing
GB/T 9278, Temperatures and humidities for conditioning and testing of paint specimens
GB/T 13452.2, Paints and varnishes - Determination of film thickness
GB/T 20777, Paints and varnishes - Examination and preparation of samples for testing
GB/T 37356, Paints and varnishes - Lighting and procedure for visual
assessments of coatings
3 Terms and definitions
The following terms and definitions are applicable to this document.
3.1 Flexibility
The ability of the coating film or putty film to deform along with its substrate without damage.
According to the provisions of GB/T 20777, inspect and prepare test samples. 4.3 Test panel
4.3.1 Substrate
Unless otherwise specified, the substrate shall be tinplate. The tinplate shall meet the technical requirements of GB/T 9271; the dimensions are 120 mm ?? 25 mm ?? (0.20 mm ~ 0.30 mm).
4.3.2 Substrate processing and test panel coating
Unless otherwise specified, process each piece of substrate according to GB/T 9271; then, apply coating of the test product or system according to the specified method.
4.3.3 Drying and conditioning
Each coated test panel shall be dried (or baked) and maintained under the specified conditions for the specified time. Test panels that are not maintained under the conditions that are specified in GB/T 9278, such as drying, shall be conditioned for at least 16 h under the conditions that are specified in GB/T 9278 before the test.
4.3.4 Thickness of coating films
The thickness of the coating films shall be specified or agreed. The
determination of the thickness of coating films shall be performed according to one of the methods to determine the thickness of dry films that are specified in GB/T 13452.2, in micrometers (??m) or millimeters (mm).
4.4 Test procedure
4.4.1 Number of tests
Perform three tests on the same spindle.
4.4.2 Test environment
Unless otherwise agreed, the test shall be performed under the environment that is specified in GB/T 9278.
4.4.3 Test
Place the coating films of the test panel upwards; use both hands to press the test panel on the spindle of the specified diameter of the flexibility tester of coating films (4.1.1); use two thumbs to bend the test panel around the spindle at a steady speed within 2 s ~ 3 s. After bending the test panel, the two thumbs 3 -- Spindle 1;
4 -- Spindle 2.
Figure 3 -- Schematic diagram of the flexibility tester of putty films
5.1.2 Magnifier
4x magnifier.
5.1.3 Waterproof abrasive paper
Suitable waterproof abrasive paper, such as No. 120, No. 180, No. 320, No. 400, No. 500 waterproof abrasive paper.
5.2 Sample
According to the provisions of GB/T 3186, take representative samples of the tested product (or each product in the multi-coating system).
According to the provisions of GB/T 20777, inspect and prepare test samples. 5.3 Test panel
5.3.1 Substrate
Unless otherwise specified, the substrate shall be tinplate. The tinplate shall meet the technical requirements of GB/T 9271; the dimensions are 155 mm ?? 70 mm ?? (0.20 mm ~ 0.30 mm).
5.3.2 Substrate processing and test panel coating
Unless otherwise specified, process each piece of substrate according to GB/T 9271; then, apply coating of the test product or system according to the specified method.
5.3.3 Drying and conditioning
Each coated test panel shall be dried (or baked) and maintained under the specified conditions for the specified time. Test panels that are not maintained under the conditions that are specified in GB/T 9278, such as drying, shall be conditioned for at least 16 h under the conditions that are specified in GB/T 9278 before the test.
5.3.4 Thickness of putty films
The dry film or wet film thickness of putty films shall be specified or agreed; the determination of dry film thickness shall be performed according to one of the determination method of dry film thickness that are specified in GB/T 13452.2.

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