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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JG/T 25-1999 Determination for freeze-thaw resistance of film of building coatings. The following main technical changes have been made with respect to JG/T 25-1999 (the previous edition):
——the definition of temperature change resistance is added (see 3.1);
——the relevant requirements for the balance are modified (see 4.4);
——the test substrate is modified (see 5.2);
——the preparation of plate specimen is modified (see 5.3);
——the maintenance of plate specimen is modified (see 5.4);
——the test method is improved (see Clause 6).
This standard was proposed by the Ministry of Housing and Urban-Rural Development of the People's Republic of China.
This standard is under the jurisdiction of the Technical Committee on Building Products and Accessories of Standardization Administration of the Ministry of Housing and Urban-Rural Development.
The previous edition of this standard is as follows:
——JG/T 25-1999.
Test method for temperature change resistance of architectural coatings
1 Scope
This standard specifies the test method for temperature change resistance of architectural coatings.
This standard is applicable to the temperature change resistance test of architectural coatings.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3186 Paints, varnishes and raw materials for paints and varnishes - Sampling
GB/T 9271 Paints and varnishes - Standard panels for testing
JG/T 23 The preparation of plate specimens for testing of building paints and coatings
3 Terms and definitions
For the purposes of this document, the following term and definition apply.
3.1
temperature change resistance
capability of the coating of withstanding alternating cold-hot temperature changes while maintaining its original properties
4 Instruments and apparatus
4.1 Cryogenic box: with temperature controlled within (-20±2)℃.
4.2 Thermostat: with temperature controlled within (50±2)℃.
4.3 Thermostatic water bath: with temperature controlled within (23±2)℃.
4.4 Balance: with a weighing range of 500g and a sensitivity of 0.01g.
5 Preparation and maintenance of plate specimens
5.1 Sampling
Sampling shall be conducted in accordance with those specified in GB/T 3186.
5.2 Test substrate
5.2.1 Asbestos-free cement slab shall be adopted and shall comply with GB/T 9271.
5.2.2 Size of substrate: 150mm×200mm×(4~6)mm. Quantity of substrates: four blocks in each group, including three plate specimens for test and one plate specimen for comparison.
5.3 Preparation of plate specimens
Plate specimens shall be prepared according to JG/T 23.
5.4 Maintenance of specimen
Place the finished plate specimen with coated surface upward horizontally on the test bench, and maintain it in the environment where the temperature is (23±2)℃ and the relative humidity is (50±5)% for the time specified in the product standard.
6 Test method
6.1 Treatment of plate specimen
Seal the back and four sides of the plate specimen with appropriate materials (such as paraffin, rosin, epoxy resin or methyl silicone resin), and place it in the environment as specified in 5.4 for 24h.
6.2 Test procedures
6.2.1 Soak the plate specimens in a thermostatic water bath with a water temperature of (23±2)℃ for 18h. The spacing between plate specimens shall not be less than 10mm.
6.2.2 Take out the plate specimens and laterally place them on the test frame at a spacing not less than 10mm. Then, put the test frame into the cryogenic box which has been pre-cooled to (-20±2)℃ (or agreed temperature), and freeze it for 3h after the temperature in the box reaches -18℃ (or agreed temperature).
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Instruments and apparatus
5 Preparation and maintenance of plate specimens
6 Test method
7 Result evaluation
8 Test report
