Any paint that uses water as a solvent or as a dispersion medium can be called a water-based paint. It is mainly used for the protection and decoration of bicycle surfaces. It is suitable for bicycle water-based paints formulated with water as the main dispersion medium and synthetic resin as the main film-forming substance. Not suitable for electrophoretic coatings. CHINA's testing standard for bicycle water-based coatings is HG/T 5370-2018 "Bicycle Water-based Coatings". Today we will introduce the regulations of HG/T 5370-2018 on the preparation of test samples for bicycle water-based coatings.
Substrate selection and treatment methods
Unless otherwise agreed, the tin plate, steel plate and aluminum plate used for the test shall comply with the requirements of GB/T 9271-2008, the treatment of the tin plate shall be in accordance with the provisions of 4.3 in GB/T 9271-2008, and the treatment of the steel plate shall be in accordance with GB/T 9271 -2008 in 3.5, and the treatment of aluminum plates is in accordance with GB/T 9271- 2008 in 6.2; the steel plate used in the salt spray resistance (for steel substrate) test is treated with phosphating solution, and the phosphating solution, etc. The treatment reagent and pretreatment process can be agreed upon by both parties. The agreed substrate material type and substrate treatment shall be stated in the inspection report. If the test method is applicable, test pieces can also be used for testing.
Preparation of test panels
1. First, we take a 150 × 70 × (0.2~0.3) tin plate to test the workability and drying time. Spray 1 coat on the tinplate plate by spraying, so that the paint is evenly coated on the tinplate plate. If there is no difficulty in the spraying process, it can be rated as "construction barrier-free". Then dry it to a film thickness of (23 ± 3) μm to make a sample.
2. Take a 150 × 70 × (0.2~0.3) tin plate to inspect the appearance and impact resistance of the coating film. Visually observe whether there are orange peel, wrinkles, stains, particles, shrinkage cavities, etc. on the surface of the sample under scattered sunlight. If there is no phenomenon, the appearance of the coating film can be evaluated as "normal". Spray 1 coat evenly on the tin plate, then dry it to a film thickness of (23±3) μm, make a sample, and test it after curing and curing according to the actual temperature and time.
3. Take the 150×70 base material agreed upon by both parties . Spray 1 coat, let the paint evenly coat the tin plate, then dry it to a film thickness of (23±3) μm, make a sample, and test it after curing and curing according to the temperature and time agreed by both parties .
4. Take a 150 × 70 × (0.45~1.05) steel plate for cupping test. Spray one coat evenly on the steel plate, then dry it to a film thickness of (23±3) μm, make a sample, and test it after curing and curing according to the temperature and time agreed by both parties .
5. Take a 150 × 70 × (0.2~0.3) tin plate for bending test of the composite paint layer. Spray 1 primer, 1 primer, 1~2 varnishes, or spray 1 primer, 1 solid color paint, 1~2 varnishes, after each spraying according to the agreement of both parties The temperature and time of curing and maintenance, the dry film thickness of the primer is (23±3) μm, the dry film thickness of the base color is (12±3) μm, and the dry film thickness of the solid color paint is (23±3) μm, The total thickness of the dry film of the varnish is (23±3) μm; the board can also be made by the supporting system agreed by both the paint supplier and the buyer. The paint variety, number of coats, interval time between coats, thickness of coat, curing and curing conditions and other requirements of the supporting system shall be provided by the paint supplier.
6. Take the 150 × 70 base material agreed upon by both parties . Spray 1 coat of primer, 1 coat of base color paint, 1 coat of varnish varnish, or spray 1 coat of primer, 1 coat of solid color paint, and 1 coat of varnish. After each spraying, follow the agreed Temperature and time curing and curing, the dry film thickness of the primer is (23±3) μm, the dry film thickness of the base color is (12±3) μm, the dry film thickness of the solid color paint is (23±3) μm, and the varnish The total thickness of the dry film of the paint is (23±3) μm; the board can also be made by the supporting system agreed by the paint supplier and the buyer. The paint variety, number of coats, interval time between coats, thickness of coat, curing and curing conditions and other requirements of the supporting system shall be provided by the paint supplier.
7. Take a 150 × 70 × (0.45~1.05) steel plate, spray 1 primer, 1 primer, 1~2 varnish, or spray 1 primer, 1 solid color paint, 1 One to two varnish methods. After each spraying, cure and maintain according to the temperature and time agreed by both parties. The dry film thickness of the primer is (23±3) μm, and the dry film thickness of the base color is (12±3) μm . The dry film thickness of the solid color paint is (23±3)μm, and the total dry film thickness of the varnish paint is (23±3)μm; the board can also be made by the supporting system agreed by the paint supplier and the buyer. The paint variety, number of coats, interval time between coats, thickness of coat, curing and curing conditions and other requirements of the supporting system shall be provided by the paint supplier.
8. Take the 150 × 70 base material agreed upon by both parties . The edge and back of the test panel shall be sealed before testing. Soak it in water for a specified period of time, take it out and wipe it dry, and perform an appearance inspection immediately. If at least 2 of the 3 test panels have no coating film pathological phenomena such as blistering, softening, wrinkling, cracking, falling off, obvious discoloration, and obvious gloss change, it is rated as "no abnormality".
9. After the heat and humidity resistance test, take out the sample plate for observation. After the artificial weather aging resistance test, take out the sample board for observation. The light source is UVB-313. The test conditions are irradiation for 4h [irradiance 0.68W/㎡, blackboard temperature (60±3)°C], condensation for 4h [blackboard temperature (50±3)°C], this is a cycle, alternately, continuous test 168h . Spray 1 primer, 1 primer, 1~2 varnishes, or spray 1 primer, 1 solid color paint, 1~2 varnishes, after each spraying according to the agreement of both parties The temperature and time of curing and curing, the dry film thickness of the primer is (23±3) μm, the dry film thickness of the base color is (12±3) μm, the dry film thickness of the solid color paint is (23±3) μm, the cover The total thickness of the dry film of the varnish is (23±3) μm; the board can also be made by the supporting system agreed by both the paint supplier and the buyer. The paint variety, number of coats, interval time between coats, thickness of coat, curing and curing conditions and other requirements of the supporting system shall be provided by the paint supplier.
