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0 Introduction:
powder coatings have the characteristics of low pollution and high efficiency, simple process control, wide range of use and construction.
but the weather-resistant powder coatings in the existing technology, both weather-resistant pyrethroid polyester or weather-resistant hydroxy polyester as the main body, in terms of durability performance can not meet the higher requirements of customers.
the film-forming material of outdoor polyester system powder coating is mainly polyester resin, the performance of polyester resin determines the performance of powder coating
.
polyester resins are wire-type or slightly branched chained polymer compounds that are polyols, polyic acids that are polymerized at high temperatures.
due to the molecular structure of polyester resins.
powder coating in the use of the process showed poor weather resistance defects, mainly as:
powder coating cross-link density is low, solvent resistance, poor heat resistance;
Powder coating in the process of use, by light, moisture, oxygen, chemical media and biomass enzymes and other environmental factors under the combined effect of loss of light, color change, powdering, foaming, shedding and other aging phenomena, limiting the application of powder coating.
With the development of the national economy and the continuous improvement of people's living standards, the requirements for decorative, weather-resistant, chemical- and chemical-resistant, water- and adhesive-resistant coatings are becoming more and more high, so the demand for ultra-weather-resistant powder coatings is increasing day by day.
Zhanxin, a long-standing manufacturer of polyester resins for powder coatings, has been developing products to meet customer needs, and has decades of research experience in ultra-weather-resistant polyester for powder coatings.
1 Experimental part
We know that polyester resins are polyols and polyacids that are polyester by high temperature, and ultra-weather-resistant polyester resins are different from ordinary polyester, the main raw materials used are relatively limited, roughly:
is different from ordinary weather-resistant resins, such as benzoic acid, ethylene glycol, glycol, methamphetamine and other less weather-resistant raw materials will not be used in ultra-weather-resistant polyester.
coating aging refers to chemical and physical changes caused by exposure to external environments, such as decreased mechanical strength, reduced bonding force, color change, brittleness, powdering, loss of luster, etc.
anti-aging ability of coating is one of the important signs of good or bad coating performance.
degradation is mainly light-induced oxidation and hydrolysing, the main factors are sunlight (especially ultraviolet light), temperature, oxygen, water and pollutants.
studies have shown that photooxidation degradation increases with increased humidity, and hydrodegradation also increases due to light.
rate of aging degradation varies depending on the location of exposure, time, coating composition, and substation metal.
on-site sun exposure experiment can give an ideal evaluation of the anti-aging performance of the coating, and also has its irreplaceable long-cycle data value.
is now the world's more recognized sun farm for Florida sun farm, Zhanxin all the ultra-weather resin will send samples to Florida to do the sun exposure experiment.
Florida is characterized by high intensity of sunlight, high temperatures throughout the year, high annual rainfall, and high humidity.
these factors combine the harsh weather conditions of the trip to make Florida an ideal location for outdoor durability testing.
one reason many companies use Florida as an area for outdoor aging testing.
, however, because of its long cycle, it is obviously not acceptable to improve the anti-aging research of coatings, so it is necessary to use artificially accelerated aging experimental methods as an aid.
and currently mainly used to speed up aging testing methods are:
through the table below can see that QUVB and QUVA have shorter wavelengths than sunlight, so the destructive power is very strong, can not match the actual results of exposure, but can be used to assess the weather resistance of the two resins.
xenon lamps have become our primary method for evaluating resin aging properties because of the authenticity and economy of their results.
aluminum profiles have always been an important application area for powder coatings, and their weather resistance to powder coatings has been relatively stringent, including GSB in Europe, AAMA in The United States of America in Qualicoat, and GB5237.4 in China for ultra-weather resistant powders for aluminum profiles, the test standards are shown below.
we can see that Europe and the United States or mainly Florida exposure as the main test method.
2 Results Discussed
The current market for outdoor polyester system according to curing agent to be divided mainly for isocyanuric acid tri-shrink glyceride TGIC, hydroxylaminide PRIMID, shrinking glyceride PT910, PT912 and isocyanate, Zhanxin can provide you with different resins according to different curing agents.
we'll share some of our resin Florida sunburn results with you.
from the results of Florida Sun exposure and QUVB at CC 4659-0 above, quVB results in the three colors of RAL 3005, RAL 8104 and RAL 5010 are related to Florida's sun exposure results, and 600 hours of QUVB results are equivalent to 36 hours of Florida .
white, the correlation was poor, and quLVB results of different levels of titanium dioxide were inversely florida blasts.
and as shown below, different brands of titanium dioxide will have different Florida sun exposure results.
so for the white formula, we must choose the brand of titanium dioxide carefully, or you can choose another brand of resin zhan.
CC 4688-2 is an ultra-weather resistant product that improves flexibility and wetting.
especially in white recipes, we found that it significantly improved the results of white recipes in Florida.
Low temperature curing has always been a hot topic in the market, first, low temperature curing can effectively reduce energy consumption, save costs, or fast curing, improve production capacity, and second, low temperature curing products can be applied to new substrates, open up new applications.
zhanxin in order to meet the needs of the market, but also developed low-temperature cured ultra-weather-resistant resins.
we tested Florida sun exposure after curing the same product at 160 degrees and 200 degrees, and we could see that there was no significant difference between the two.
addition to the high-gloss resins listed earlier for PRIMID curing, we also have a combination for dry mixing.
in the white formula RAL9001, quLVB results do not match those in Florida, so you need to choose the right type and content of titanium dioxide to pass the Florida test.
listed above are PRIMID cured ultra-weather-resistant resins, while in the Chinese market is still dominated by TGIC curing, so I'll list some of our TGIC cured products in Florida's sun exposure results.
from here, we can see that TGIC cured products are the same as PRIMID cured products, for the white formula also need to carefully choose the model of titanium dioxide.
3 Conclusion
Zhanxin as an excellent polyester resin supplier, is committed to providing customers with:
1, ultra-weather-resistant resins with different curing systems
2, highlight, matte and even light-free ultra-weather-resistant resins
3, Standard cured and cryogenic cured ultra-weather-resistant resin
4, which meets the Florida Sunburn Test
5 that has passed more than 3 years, and some colors can pass the 5- or even 10-year Florida Sunburn Test
(Source: Zhanxin Resin)
.