The overall solution of a new type of UV-resistant and heat-resistant composite stabilizer applied to water-based light-curing coatings

Yang Yongji, Lai Wei, Xie Jieshou, Lu Zhonghan, Jane Zhixian, Dr. Huang Yaoxing / Yongguang Chemical
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water-based photo-curing coatings combined with the advantages of water-based coatings and photo-cured coatings, with high productivity and fast drying speed, and can avoid the traditional ultraviolet curing coatings will release VOC problems, so increasingly attention to the market. However, environmentally friendly water-based photocuring coatings also encounter many challenges, such as exposure to natural sunlight, the coating will produce deterioration and powdering phenomenon, and this part can be added water-based photocuring light stabilizer Eversorb® AQ7; There is also the problem of fading of near-visible light sensitive light curing materials, which will shorten the service life of the product, leading to negative consumer evaluation of the product and manufacturer, and finally, the hot yellowing and color difference caused by the high temperature baking of the film, which has great limitations on the application of the product .
This paper develops the compound light stabilizer NLS1 for the yellow change produced instantly after the water-based photo-curing coating, and the NLS2 with high UV barrier resistance demand for the fading of light-sensitive light-sensitive, and NLS3 developed for the suppression of high temperature baking yellow change, mainly by applying the test design (DOE) test technique, the test results show that: NLS1, NLS2 and NLS3 do not have a negative impact on the speed of light curing, and according to the test results, NLS1 can effectively slow down the instantaneous solidification of water-based photo-curing coatings Yellowing, for the mitigation of instant curing yellowing effect of up to 75%, NLS2 can effectively slow down the near-visible light sensitive light curing material fade, for 365nm UV barrier impact of 62.5%, membrane thickness impact of only 20. 9%, for 380nm UV barrier influence of 47.7%, membrane thickness impact of only 27.4%, showing that the addition of NLS2 compared to film thickness can effectively block 365nm and 380nm wavelengths. , for the protection of near-visible light sensitive UV material fading has a very good effect, NLS3 can effectively slow down the film after high temperature baking caused by yellowing, after 120 degrees C baking 10 hours results show that the effect of slowing hot yellowing is 78.82%, membrane thickness impact is only 17.23%, showing that NL3 for slowing the instant yellowing and weather protection also has a certain effect.
keywords: photo-cured coatings; water-based photo-cured coatings; photosodulation; light stabilizers; yellowing; instant yellowing; experimental design; UV barrier; thermal yellowing
According to a 2016 report by Market and Markets Research Private Ltd., a global market research firm, the global market for water-based photo-curing resins was estimated to reach about $122.2 million in 2020. 230.3 million U.S. dollars in size, 2015-2020 compound growth rate of about 13.52 percent, its growth momentum mainly comes from the paint market for low pollution, low energy consumption, human harmless product demand increased significantly, coupled with the increasingly stringent VOC emission standards, the original use of solvent-based coatings in the field also tend to use low VOC, rapid curing of coating products, thus driving the overall industry to water-based photo-curing field development. Regionally, the European Union region due to the implementation of VOC emission restrictions for many years, high popularity, is currently the largest market, and China because of the "13th Five-Year Plan" officially set green development as the core goal, the paint industry is facing from solvent-based upgrade to environmental protection products in the transition period, is expected to be the highest growth rate of the market.
-based photo-curing coatings are widely used in wood furniture, floor coating, printing inks, plastic surfaces, such as cosmetics or 3C product shell coating and other fields. Inherited the characteristics of traditional photo-cured coatings and water-based coatings, water-based photo-curing coatings have solvent-free, low VOC emissions, rapid curing into film, shorten the construction cycle, reduce the overall cost and other advantages.
main features of photo-curing coatings: 1, coating film curing speed, shorten the coating film drying time;
When the photo-curing coating is exposed to UV light, unsaturated double bonds in the polymer structure or in the process of unreal matter can easily break the bonds and deteriorate, resulting in a free-form chain reaction, resulting in a hair color group, resulting in resin yellow fade and cracking, as shown in Figure 1.
the current coatings industry to solve the optical cracking method for ultraviolet absorbent (UVA) with blocked amine light stabilizer (HALS). However, in the process of photocuring coating drying, light trigger and light stabilizer will compete for ultraviolet energy, which causes conflict in the light curing coating drying mechanism, resulting in the number of times the photocuring must be repeated to increase the production cost, and the coating film is repeatedly exposed to light-cured UV lamp source will lead to poor weather resistance. The new light stabilizer Eversorb® UR210S can solve this problem without affecting the adhesion of the photo-curing coating, which is still 5B in testing with a 100-grid knife.
environmental trends, water-based photo-curing coatings can solve the problem of volatile organic compounds (VOCs) released by traditional UV-cured coatings. However, environmentally friendly water-based photo-curing coatings also encounter many challenges, the first is exposed to natural sunlight, easy to cause changes in appearance of color and coating deterioration and powdering, and currently can be added water-based photo-curing stabilizer to prevent the production of light deterioration; Will affect product quality, increase the cost of production, the third is near-visible light sensitive photo-curing material fading problem, will shorten the life of the product, leading to negative consumer evaluation of products and manufacturers, and the fourth is after the film by high temperature baking often caused by yellow change / color difference changes, for product applications have great restrictions.
In present, there is less research on the application of photostabilizers to water-based photo-cured UVs, so the effects of different types of water-based ultraviolet absorbents (UVA), blocked amine photostabilizers (HALS) and new water-based photostabilizers (NLS) on photo-curing are discussed by using experimental design techniques, and finally the optimal hydro-curing photostabilizer NLS1 and NLS2 are further selected. And NLS3 description: NLS1 to slow down the water-based photo-curing coating instant curing yellowing study, NS2 to slow the near-visible light sensitive photo-curing material fading, and for different concentrations and different film thickness for 365nm and 380nm UV band barrier effect and yellowing influence change research, NS3 to slow the high temperature baking yellowing study. The reaction surface map is used to obtain the UV barrier that cures yellowing instantly after curing the model, slows down the fading of the near-visible light sensitive light curing material, and slows down the high temperature baking yellow becomes the optimal area solution.
test
test raw materials
water-based photo-cured polyurethane (Bayhydrol® UV2282), industrial grade, Bayer Chemical Industry Co., Ltd.; optical starter (Irgacure® 500), industrial grade, BASF Chemical Industry Co., Ltd.; water-based photo-curing Photostatists (NLS1-NLS2), water-based photo-curing heat-resistant complex (NLS3), industrial grade, Taiwan Yongguang Chemical Industry Co., Ltd.;
test equipment
. UV photo-curing tester: Factory Taiwan Csun Zhisheng / Model (UVC- 2 0 1M); Model (QUV/B a s i c); Chroma meter: Factory M I N O L T A / Model (CM- 3 5 0 0 d); Hot Air Cycle Oven: Factory Seoyama Instrument/Model (DV452).
test method
preparation and curing of water-based photo-cured polyurethane coatings
first emulsifying water-based photo-cured polyurethanes (Bayhydrol® UV2282) and light triggers (Irgacure® 500) After the product is mixed with a certain proportion into a water-based photo-curing coating, said to take different types of light stabilizers (as shown in Table 1) mixed, with a coating coating device to the configured coating uniformly coated in 10cm×7cm×0.1cm horse port iron plate and glass test pieces.
conditions: the oven is dried at 60 degrees C for 2 minutes and then placed in a condition of 1x150 w/cm (high-pressure Hg lamp lamp) in an air environment.
-test method
Minimum energy test required for photo-curing
Minimum energy required when the surface of the paint film reaches full curing, and the energy required for curing is recorded using a high-energy UV radiometric to determine the dry table as the standard based on the nail touch coating film.
yellow change test after light solidification
water-based photo-curing coating mixed with different types of light stabilizers and coated on the test sheet, after curing conditions, the use of chroma machine yellow change test.
artificial accelerated aging test
. ASTM G154-1 (revaed in 2006), test standard (340nm 60C 8hUV lighting/50C4h condensation), using a chroma meter to observe changes in the accelerated aging test process.
wavelengths 365nm and 380nm UV barrier tests
using additional functions in the chroma meter to observe 365nm and 380nmUV barrier changes during accelerated aging tests.
the hot baking test
the change of hot yellow by fixing the baking time and conditions.
Software Name and Analysis
Using Software: JMP version 5.0 (SAS Institute)
Analysis using built-in analysis tools
Results and discussion of the effects of
different types of light stabilizers and different film thicknesses on photo-curing speed
Test parameters and analyze the results, and more importantly, use screening design to identify different types of light stabilizers: water-based UV absorbers (WUVA), water-based photo-curing light stabilizers (NLS, including NLS1 and NLS2), water-based UV absorbers (WHALS) and different dry film thicknesses (DFT) on photo-curing speed. The pilot plan is shown in Table 3, and the results of the experimental data analysis from Table 3 are as shown in table 4 parameter estimation table and Table 5 variation analysis (ANOVA) table.
: R2 (judgment coefficient) indicates the model's explanatory power, and R2 is available, indicating that the model has a strong explanatory power. Adjusted R2: The adjusted determination coefficient is also used to indicate the explanatory power of the model, which is more objective than R2. 「R2」「R2」,,「R2」t:,「t」,p(prob):,「」,()p(prob):,「」,()p<0.05
(UVA)
:(WUVA)(Prob>│t│0.05),,(Y),, That is, to reduce the speed of light curing and reduce the production efficiency of light curing. This is mainly due to the simultaneous competition between UV absorbers and light triggers for UV light energy, with an impact of 10.1% (as shown in Table 6). In addition, equation (1) has an intercept term value of 0.0659, which means that no light stabilizer has been added and that, regardless of the thickness of the dry film (all the causes in the equation are subsortured by zero), the water-based photo-curing coatings in this test are essentially the lowest energy required for curing (J/cm2).
(HALS)
:(HALS)(Prob>│t│0.05),,(Y)。 The speed of light curing is also negative, with an impact of 18.6% (as shown in Table 6) larger than UVA. Mainly because HALS itself is a free-based catcher, it is possible to react with free-form in advance to terminate the photo-curing process, resulting in a significant reduction in the speed and productivity of photo-curing.
effect of film thickness (DFT) on water-based photo-curing minimum curing energy
analysis shows that although dry film thickness (DFT.) is an important factor affecting the speed of light curing (Prob> However, its coefficient of 0.001879 is quite small, indicating that the dry film thickness compared with other factors (i.e., light stabilizers), the impact is small, and its coefficient is negative, indicating that the dry film thickness thin system than the dry film thickness system needs a higher light energy to cure. Mainly because in the free-form polymer polymerization reaction, oxygen in the dry film thickness thin system, the speed of entry and exit than the dry film thickness system is fast, so the need for higher light energy to produce free-form, to fill the oxygen polymerization reaction waste of free-form, so the thinner the dry film thickness system, the higher the required light curing energy.
The effect of the new light stabilizer (NLS) on the water-based photo-curing minimum curing energy
from the analysis results show that the new light stabilizer (NLS) is not an important factor affecting the speed of light curing (Prob> t-t-05), regardless of the thickness of the dry film, will not cause the energy (Y) required for curing. There is no effect on the curing speed of the light, with an impact of 0% (as shown in Table 6).
effects of different types of light stabilizers on instant yellowing after photo-curing
This experiment uses the test design DOE to design test parameters and analyze their results, and more importantly, to screen them.