Below are part of the quality control principles of Aluminum-plastic Composite Panel for interior of our company—DecoTech Building Materials Co., Ltd. Those items in red are for coating monitoring.
Standard "Aluminum-plastic Composite Panel" GB/T 17748-1999.
1. Appearance quantity;
1）Vestige, indistinct;
2）Coating omit, not allowed;
3）Wave, bubble, abrasion and scratch, not allowed;
4）Aberration, not allowed;
5）Spot, ≤3 pcs/㎡.
2. Dimensions deviation
1）Length ±3mm;
2）Width ±2mm;
3）Thickness ±0.2mm;
4）Diagonals windage ≤5mm;
5）Edge unstraightness ≤1mm/m;
6）Warpage ≤5mm/m.
3. Coating thickness ≥16μm.
Test sample: 500*500mm. The thickness of coating refers to the total thickness of painting. Should have a lot site on the samples tested, at least covering 5 locations of the four angles and the sample center.
4. Gloss tolerance ≤10, gloss＜70; ≤5 gloss ≥70.
5. Pencil hardness ≥HB.
Test sample: 50*75mm. Fix the pencil, which is China brand in high level, on the tester,then push it sliding on the surface of the sample. If the coating is scratched then change the flexible pencil and test again till no abrasion. The grade of pencil hardness are 9H、8H、7H、6H、5H、4H、3H、2H、H、F、HB、B、2B、3B、4B、5B、6B, while 9H is the hardnest and softest is 6B.
6. Coating flexibility ≤3T.
Test sample: 25*200mm and 200*25mm. Put the sample coating side towards outside and bending it while winding itself around to 180°, and testing the minimum rolling times with no crack and shedding of the coating. According to the flexible level, there are 0T、1T、2T、3T、4T etc. and getting non-flexible. Below is the illustration:
7. Coating adhesive should be not lower than class 1.
Test sample: 50*75mm. It is stipulated to test by rounding, adopting coating adhesive tester, using styli as pinhead, fix the sample on the test platform with the coating side face up, and make the top end of the styli come into touch with the coating, rock the crank to make uniform rotation clockwise, and the point end will scull circle with certain diameter. The radius of round turning: 5.25mm; running rapid: 80~100r/min; the total length of the nick: 8mm around. Add poise accordingly if there is no reveal of aluminum skin till the base board reveals in the nick. The circle overlap in turn, and makes a graph like cycloid. Get the samples and remove the paint pits with paintbrush, check with the quadruple magnifier and grade. There are 7 ranks of rounding coating adhesive, the best is 1 class, while 7 is the worst. For a certain part of the tested coating, qualified it if 70% grid is in good order, otherwise judged as shatter.
8. Impact resistance: 50kg·cm, no depainting and no crack.
Test sample: 50*75mm, 3 pieces. Tester: painting impact resistance tester. Put the test sample on the stithy flatly and stably with the face towards up. Adjust the impact height to 50cm, and let the ram fall down freely to impact the sample. Observe the pros and cons of the point impacted carefully, to check if there is depainting or crack. If necessary the impact location also can be painted with stain before observing. Qualified if all of the three samples can absorb 50kg·cm.
9. Boiling water resistance, no change.
Test sample: 100*100mm, 6 pieces. This test not only can tell the functions of the coating, but also the laminating capability of aluminum skin and the core materials, meanwhile it can reflect the matching performance of thermal insulation and shrinkage between the aluminum skin and core materials. It can test the comprehensive capabilities of boiling, temperature tolerance, distortion and cementation. After boiling test there should be no changes of aluminum composite panel. Put the samples into water bath in constant temperature for 2h, and the temperature is controlled at （99±1）℃, then let the samples to cool naturally in the water, pick them out and cloth dry, observe if there is bubble, discoloration, peeling off, crack and tackless etc..
10. Acid resistance, Alkali resistance, Oil resistance, no change.
Test sample: 100*100mm, each 3 pieces for acid resistance, alkali resistance and oil resistance. Tester: glass graduate with inner diameter is equal or greater than 50mm, cover of glass graduate, sealing material that can not be eroded by chemical reagent, 5%（volume）HCI、5%（quality）NaOH、2%（volume）HCI、2%（quality）NaOH、20# oil. Put one side of the glass graduate on the coating surface, and to seal and fix it with the sealing material, then import the chemical reagent to the glass graduate and make the length of the liquid level to 20mm±5mm. Cover the top of the graduate to ensure the reagent will not be affected by volatilization and air. Get the samples after making it standing 24h and wash away the reagent to check the tested coating if there is discoloration, pimpling, bubble and powder etc. with eyeballing.
11. Solvent resistance, no change.
Test sample: 100*200mm, 3 pieces. Tester: coating tester of solvent resistance, butanone, dimethylbenzene, hospital gauze. Wrap 4 layers gauze on a flexible wiper, and make it wet thoroughly with dimethylbenzene, then wipe back and forth 200 times in one section of the coating with the pressure of 1,000g±10g. Eye survey if there is exposed base. Length of wiping:100mm, frequency: 100 times/min. Interface of wiper and the test sample: 2cm㎡. Keep the gauze being wet when testing. Set the worst result as the test result.
12. Scrub resistance, no change when ≥10,000 times.
Test sample: 150*430mm, 3 pieces. Tester: coating tester of scrub resistance, 0.5% solution of laundry soap powder with the PH value between 9.5~10. Using brush which is made of bristle, it is 90*38mm with 16~19mm long mane and weighs 450 gram. The length of burshed coating is about 300mm, and there should be 100m uniform motion in the middle, while the frequency is 37 times/min. Keep the coating being wet when testing. Take down the samples after brushed 1,000 times, wash it and make it dry then look into the 100mm section carefully. To see if there is paint, aluminum skin coming out or other obvious injury. Qualify it up to grade unless there is no scratch above and all of the three samples being passed the test.
13.Face density, specified value ±0.5kg/㎡.
14. Bending strength, ≥60MPa.
15. Bending elastic modulus, ≥1.5*104.
16. Penetrating resistance, ≥5.0kN.
17. Shearing strength, ≥20.0MPa.
18. 180° peel strength, ≥5.0N/mm.
19. Temperature cycle resistance, no change.
Test sample: 350*350mm, 3 pieces. Tester: household freezer ( with 1℃ contral precision) and oven ( with 1℃ contral precision). Leave the samples in constant temperature of -40℃ ± 2℃ at least 2h, then take them out and put to the constant temperature of 80℃ ± 2℃ for 2h, that is one cycle, and this test needs to be done 50 times. When the test finished eye measure them and to see if there is some abnormal changes in appearance, such as bubble, peeling off, tackless, coating crack etc.
20. Thermal expansion coefficient, ≤4.00*10-5℃-1.
21. Heat distortion, ≥95℃.
