The gloss stability of special sand powder coating for aluminum profiles is discussed

Abstract:
introduces the special polyester/TGIC-type sand powder coating for aluminum profiles, and analyzes the gloss anomalies that often occur in the production and use of sand powder coatings. Unusual luster of sand powder coating often leads to color differences in the coating film affecting decorative, and even worse, the performance of the coating film.
, the paper analyzes and discusses the factors affecting the luster stability of the special sand powder coating for aluminum profiles, and conducts condition-comparison experiments on the various factors
the
. The final conclusion of the experiment is that the addition of sander and curing agent has a crucial effect on the luster stability of sand powder.powder coating as the fastest growing variety in a variety of coating varieties, in the production and coating process without solvent release, less pollution, in line with environmental requirements, has now become recognized in line with high production efficiency (efficiency), excellent coating performance (excelence), eco-friendly (ecology) and economic (economy) 4E paint varieties.
special sand powder coating for aluminum profiles as part of the powder coating, which obtains an art-based texture effect by adding textures to the powder coating. However, in the actual production and coating process of sand powder coating often appear gloss pattern and standard sample difference is large, affecting production efficiency, serious may produce customer powder compensation events.
aluminum profile special sand powder coating how to ensure the luster and texture stability is difficult for the powder industry. This paper analyzes from various factors to find out the way to improve the stability of special sand powder coating for aluminum profiles.
Aluminum profile special sand powder coating is generally in the powder coating to add sand and sand additives through physical or chemical action, after the powder coating melting level curing, in the coating surface to form a unique texture effect of the rules. As with other textured powder coatings are susceptible to production and spraying, curing factors, poor stability, generally manifested in gloss and texture. The influence of various factors such as production, spraying and curing on the gloss and texture of sand powder is discussed separately.
the production process of powder coating, in order to disperse the parts evenly, the material needs to be melted and mixed by the molten extruder, so that its various parts are further dispersed evenly. Melt extrusion mixing process is indispensable in the process of manufacturing powder coatings and is one of the key processes related to product quality.
same material of the same material in different extruders produced a large difference in gloss, there may be more than 3 degrees (60 degrees gloss) difference. However, the same material in the same extruder repeated extrusion, product gloss basically remains unchanged. It is generally believed that differences in the mixing effect of different extruders can lead to differences in time and texture in the production of sand powder coatings. Experienced craftsmen can adjust the formulation to reduce the difference in the gloss of the sand products from different machines.
powder coating products can also adjust the coating gloss and surface by adjusting the particle size. In general, the pattern and gloss of sand powder are often controlled by appropriately raising or decreasing the particle size. However, the adjustment of this mode of gloss adjustment range is relatively limited, because the grain size of the sand grain is too small, resulting in a low powder rate on the powder, increase powder consumption. The grain size is thick, the gloss is lower, and the decorative effect is affected. In order to ensure the batch stability of the product, the particle size difference between the same product batches can not be too large.
the difference of extruder mixing effect and the control of powder particle size distribution, the product stability of sand powder coating can be guaranteed by recording the parameters of each production line in actual production.
1,
1.1 raw materials
test materials using Linyi Owen Powder Coatings Co., Ltd. users of external aluminum profile powder coating materials. Experimental powder coating sample powder using Linyi Owen Powder Coatings Co., Ltd. production of outdoor aluminum profile powder coating products.
1.2 device
GYP-2030 experimental small twin screw extruder; ACM-05F vertical grinder; ED-400 coating thickness meter; electrostectrectroscopic spray gun; WGG60-Y4 Glossy Meter;
1.3 Experimental Method
There are many factors in the production of sand powder coating products from production to customer use that affect the gloss and surface effect of the coating film, and we will experiment with these factors as follows.
1.3.1 coating thickness of the spray work piece
select powder A, powder B two different powders, respectively, spray 40 to 60 m, 60 to 70 m, 70 to 80 m, 80 to 90 m, 100 m or more different film thickness samples each 2 pieces. After full curing, remove the model and cool down to room temperature test model gloss, take the average record of 2 model glosses under the same film thickness.
1.3.2 curing temperature of the coating film
select powder C, powder D two different powders, electrostatization sprayed at 190 degrees C/10 min, 200 degrees C/10min, 220 degrees C/10min three different curing conditions for curing, after curing to remove the sample plate cooled to room temperature test plate gloss.
1.3.3 curing time of the coating film
select powder E, powder F two different powders, electrostitive spraying after 200 degrees C/10min, 200 degrees C/30min two different curing conditions for curing, after curing out the sample cooling to room temperature test plate gloss.
1.3.4 Addition of sand additives
Select a conventional aluminum profile sand powder coating formula, adjust the addition of sandstones and sand additives, respectively, in-house oven curing and customer curing furnace curing, comparing the same formula gloss changes under different conditions.
1.3.5 Curing dose in the formula
select a conventional aluminum profile sand powder coating formula, adjust the amount of curing agent, respectively, in-house oven curing and customer curing furnace curing, comparing the same formula gloss changes under different conditions.
2, results and discussion
2.1 spray workmandust thickness from Table 1, the greater the difference in film thickness, the greater the gloss difference, in general, the film thickness in 40 to 80 m time changes in about 1 degree, relatively stable, color deviation is not very large. When the film thickness is more than 100 m, the gloss is more than 2 degrees different from the normal film thickness, and the color difference between the two is very large. And the surface pattern is thick, three-dimensional sense is weakened, and the normal film thick surface is very different.
in light-colored sand powder coating, the film thickness is less than 40 m may be due to insufficient cover force to appear the bottoming phenomenon, when the thick coating of the work piece and the color difference between the thin coating is greater; Sand powder spraying generally requires the film thickness in 40 to 80 m or so, the film thickness is too thin to easily cause the cover is not enough, can not play the role of decoration and protection of the substrate; The thickness of the coating film has a great influence on the gloss of the sand powder.
2.2 the curing temperature of the coating film From Table 2, it is learned that the sand powder coating in the 190 to 220 degrees C curing temperature range, temperature changes on the sand powder gloss has little effect, generally in the gloss change of less than 0.5 degrees. However, the sand powder coating has a thicker surface texture under 190 degrees C/10min curing conditions than under 220 degrees C/10min curing conditions.
thermosoensate powder coating does not occur cross-linking reaction at room temperature, powder coating curing needs to be in a certain temperature range before cross-linking reaction. The powder coating used in aluminum profiles is generally cured at a temperature of about 200 degrees C. The low curing temperature causes the degree of crosslinking of the coating to be incomplete, which affects the performance of the coating. The curing temperature is too high, which will cause irreversible damage to the coating, causing the coating to lose light, change color, powder and other changes.
Although the gloss of the sand powder coating can be considered insensitive to temperature within a certain temperature range, the curing temperature can affect the other properties of the sand powder, thus ensuring as much stability as possible in the curing temperature of the sand powder.
2.3 The curing time of the coating It is learned from Table 3 that the curing time is extended from 10min to 30min under the condition that the sand powder coating is fully cured, and the gloss change of the sand powder coating is very small at about 0.5 degrees. It is stated that the appropriate extended curing time under the premise of ensuring the full curing of the sand powder coating has little effect on the gloss of the sand powder coating.
two important indicators in the curing process of powder coatings: one is the curing temperature and the other is the curing time. The curing process of powder coatings takes some time to complete. If the curing time is too short, it is easy to cause the coating curing is not complete, the coating performance can not meet the national standard requirements. And the curing time is too long easy to cause the coating over-curing, coating loss, yellowing and other destructive effects, resulting in coating performance is not up to the national standard requirements. The length of film curing time in the laboratory can be very good control, but in the actual spraying of customers, vulnerable to chain speed, work part size, curing furnace and other factors make it difficult to control.
2.4 The amount added to the sand aid From Table 4, it is learned that the increase of sand additives on the gloss stability of sand powder coating is not conducive, sand additive addition is greater than 0.2%, sand powder coating gloss stability began to get worse, 0.3% time difference of more than 1 degree, and with the increase of sand coating additives, gloss stability rapidly reduced. Therefore, as far as conditions permit, as far as possible to ensure that the addition of sand additives less than 0.3%. This ensures the stability of the gloss of the sand powder coating.
usually sand powder coating in the production process not only through the amount of sander to control the surface effect of the coating film, but also add sand additives to use together. Among them, the quality and dosage of the sanding aid play a great role in the gloss and texture of the coating film of the sand powder coating. Sander is generally fluorine fluoride temperature resistance is very good but the corrosion resistance of sand additives is generally poor, 220 degrees C above the temperature of baking often appear sand additives are baked bad situation.
the curing dose in the 2.5 It is learned from Table 5 that the amount of curing dose in the formula has a great effect on the gloss stability of the sand powder coating, especially when the curing dose is insufficient, the gloss of the sand powder coating changes greatly. The slightly excessive curing agent has little effect on the gloss of the sand powder coating.
the appropriate overdose of curing agent will improve the gloss stability of sand powder coating, but the relative cost will increase, and too much curing agent will also cause powder storage stability is poor, easy to produce clumping phenomenon and other disadvantages.
in thermostate powder coatings, curing agents are an essential component in the composition of powder coatings. Without curing agent thermosolytic powder coating, it is not possible to cross-cur the film to obtain a coating film with certain physical and electrometic properties and chemical resistance. In the formulation design process, we must first consider the type and dosage of curing agents that are fully required for coating film curing.
3, Conclusion
The experimental results show that: the greater the difference in the thickness of the
(1) aluminum profile sand powder coating film, the greater the gloss change; The thickness of the coating film is generally between 40 and 80 m, and the
(2) sand powder coating has little effect on the gloss of the sand powder (aluminum sand) in the temperature range of 190 to 220 degrees C. The powder curing temperature is 200 degrees C;
(3) the sand powder coating film is within 30min, the length of curing time has a slight effect on gloss, negligible (aluminum profile powder curing time is 15 min);
(4) The increase of sand additives is not conducive to the gloss stability of sand powder coating, and with the increase of gloss stability of sand additives, the amount of curing dose in
(5) formula has a greater impact on the gloss stability of sand powder coating. In particular, the gloss of the sand powder coating changes greatly when the curing dose is insufficient. The slightly excessive curing agent has little effect on the gloss of the sand powder coating.