Study on the effect of powder coating Tg on coating performance

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Abstract
This paper selects different polyester resins and different formulations to prepare the corresponding powder coating, after coating curing to determine the coating Tg, and the curing coating for thermal transfer, scratch resistance, chemical corrosion resistance, water resistance detection, analysis of the effect of coating Tg on the above coating performance.1
Foreword
thermoo-solid powder coating, also known as dry paint, is a solid powder coating consisting of thermo-solid saturated polyester resins and curing agents, pigments, fillers and additives.
is an environmentally friendly product, with environmental protection, economy, efficiency, excellent performance and other advantages, can provide a wide variety of colors and varieties of powder coatings, and paint film plump, high gloss, smoothness .
more and more industries and fields began to use powder coatings. Coating performance is critical for powder coatings, which have a decisive impact on the practical application of powder coatings.
Tg, or glassy temperature, refers to the temperature at which a substance transitions from a solid state to a molten state. The importance of Tg in powder coatings is well understood, and the phenomenon of powder coating lumps in summer is the most common example.
coating Tg after the powder coating has been cured has been paid little attention to and studied, and the effect of coating Tg on the partial properties of the powder coating will be verified experimentally below.2
experimental part
2.1 experimental materials 2.2 instrument equipment extruder, coffee grinding, screen, flat-panel hot paint machine, transfer paper, analytical balance, DSC differential scanning volume heater, cold-rolled steel plate, binder oven, electrostature spray gun, BYK glosser, pencil hardness meter.2.3 Experimental Formula
A commonly used resin in the field of powder, of which resin A (Tg:68.57 degrees C), resin B (Tg:64.35 degrees C), resin C (Tg:60.60. 48 degrees C), three resins for the outdoor TGIC 93:7 series, resin D (TG:57.69 degrees C) and resin E (TG:52.43 degrees C) for the indoor 50:50 series.2.4 Experimental step 2.4.1 Preparation of powder coatings
Ingredients in accordance with the above basic formula, fully premixed in the extruder after melting extrusion, cooling pressure, initial crushing with coffee grinding, through 200 mesh screening powder.2.4.2 Preparation of the coating
using an electrostature spray gun to evenly spray the resulting powder coating on a clean cold-rolled steel plate, finish the spray, put in the oven to bake under curing conditions, cure it, and remove the model. Several double-sided spray samples are prepared to detect the acid resistance of the coating.2.4.3 Tg detection of powder coatings and coatings
take test samples 20.0mg, using MDSC-2910 differential scanning thermal instrument test, heating and cooling rates are 10 degrees C/min, nitrogen flow of 50mL/min.
2.4.4 Thermal Transfer Treatment
the high-precision ink transfer paper is tiled on the surface of the above model, and the 400S is thermally transferred at 170 degrees C with a flat-panel hot transfer machine. After the transfer is complete, cool down and remove the transfer paper from the model surface.
2.4.5 Water resistance testing
the initial gloss of the coating is measured with a BYK gloss meter and recorded, the sample to be measured is placed in boiling water, maintained at 2h, the model is removed, the surface of the coating after boiling is wiped clean, and the coating gloss is measured, recorded.2.4.6 acid-base resistance test
the above-mentioned models are suspended in 5% alkali solution and 3% acid solution, respectively. Observe changes in coating status at 24h intervals to see if there are any phenomena such as loss of light, foaming, powdering, etc.
2.4.7 Scratch Resistance Detection
gradually improves the hardness of the pencil used, using a pencil hardness meter, and scratching performance testing of the coating by leaving a mark after the pencil is crossed.3
and discussion
3.1 powder coating and its coating Tg
test results powder and coating Tg as shown in the table below.3.2 Thermal Transfer Effect
After observation, the transfer results are summarized and listed in the table below by the ease of tearing the paper and the clarity of the texture. Comparing the above results, from Table 3 and Table 4, it can be seen that the outdoor three resins C coating Tg the lowest, the most difficult to tear paper, A coating Tg the highest, tearing paper easy, transfer tear paper easy order for A coating, B coating, C coating.
house resin D coating Tg than E coating Tg is higher, transfer tear paper E coating is difficult to tear paper, because D coating Tg is also relatively low, transfer tear paper is also more difficult, but tearing paper effect is better than E coating. 3.3 Water resistance results From Table 5, it can be seen that after 2h boiling water boiling, the gloss of each coating will be reduced, three resins, A coating gloss drop small, high preservation rate, C coating glossy water after cooking decreased significantly, low light preservation rate.
B-coated water-cooking gloss and preservation rate between A and C. After the house D and E water are boiled, the E coating gloss decreases significantly. 3.4 acid-base resistance results the results of the experiment white and yellow formula consistent, is listed in the table below.
as can be seen from Table 6, three outdoor products, acid resistance: A is better than B is better than C, C coating acid resistance is the worst, the earliest began to lose light, and soon the coating fell off, A coating acid resistance is excellent.
D and E, D acid resistance is better than E acid resistance. By Table 7 can be found, outdoor A, B, C alkaline resistance: A coating alkali resistance is the best, minor loss of light and powder after a long time after complete powdering, C coating first began to lose light and powder; 3.5 Anti-scratch performance results As can be known from Table 8 results, scratch resistance A coating is the best, in between 1H-2H, E coating scratch resistance is the worst, between B-HB. 4
Conclusion
This paper studies the effect of coating Tg on the coating performance of powder coating from thermal transfer, acid-base resistance, scratch resistance, etc., and through the above results, high-coated Tg can get better thermal transfer, acid-base resistance, water-resistant boiling, scratch-resistant performance.