Nano-titanium dioxide modified polyester-TGIC powder coating research

1、2

1.
，

2.

：，-TGIC，，；，，。

Powder coating does not contain volatile organic compounds (VOCs, volatile organic compounds), which is a new type of environmentally friendly coating, which is widely used in various fields such as home appliances, automobiles, and building materials.

2015 sales of thermosetting powder coatings in China reached 1.
29 million tons, an annual growth of 7.
5%, far exceeding the average growth rate of 4.

Because ultraviolet light oxidative degradation is one of the main reasons for the aging of outdoor powder coatings, the commonly used anti-aging method is to separately add certain antioxidants, ultraviolet absorbers and free radical traps to slow down the aging of the coatings.

This method has been widely used in industrial production, but most of these additives are organic, such as hindered amines, salicylic acid esters, etc.

1 Test part

1.

1 Materials and preparation

Nano-grade rutile ultrafine titanium dioxide (Pangang Research Institute Co.

, Ltd.
), KH-560 silane coupling agent (Nanjing Chemical Industry), various formulation materials and processing aids (all commercially available).

1.
2 Test method

Put the prepared test sample into a fluorescent ultraviolet accelerated test box (power 36×4W) for artificial ultraviolet accelerated aging, and measure its 60° specular gloss and color value in different periods.
Analyze the morphology, size and structure of rutile nano-titanium dioxide using JEOL field emission scanning electron microscope (JSM-7500F); Japan’s Shimadzu UV-Vis spectrophotometer (UV-2550) to test the UV of rutile nano-titanium dioxide Light shielding performance, scanning wavelength range: 200nm~800nm; Shanghai Precision Optical Instrument (WGG-66) gloss meter and Japan Minolta color difference meter (CR-10) respectively measure color and gloss changes.

2 Results and discussion

2.

1 Performance and characterization of nanometer titanium dioxide

Figure 1 is a SEM photo of nano-TiO2 with a magnification of 100,000 times.

The surface-treated nano-TiO2 crystals are well developed and have a uniform particle size distribution, with a particle size of about 30-50nm.

2.
2 Anti-ultraviolet aging performance of modified polyester-TGIC powder coating

Figure 3 is the relationship between the color difference value of the polyester-TGIC powder coating modified by nano-titanium dioxide and the unmodified formulation and the artificial ultraviolet irradiation time, and Figure 4 is the relationship between the gloss retention rate and the ultraviolet irradiation time.
From Figure 3 and Figure 4, it can be seen that without the addition of nano-titanium dioxide formula (formulation c), the color difference value after artificial ultraviolet irradiation has a greater increase, and as the aging time increases, the color difference value is larger.
After the two groups of modified powder coatings were irradiated with UV for eight days, the gloss retention rate was still above 42%, while the unmodified formula was only about 10% of the initial value.
At the same time, it can be seen that the nanometer titanium dioxide after surface treatment exerts its excellent UV shielding performance.

3 Conclusion

Due to its excellent long-term absorption of ultraviolet light, nano-titanium dioxide effectively shields the ultraviolet light radiated to the exposed sample, so that the photodegradation reaction only occurs in a thin layer of the outer surface of the sample, and it also protects some organic resistance.

The aging aid is not degraded by ultraviolet rays.
In addition, due to the large specific surface area and surface energy of nano-titanium dioxide, particle agglomeration easily occurs during use and loses its original effect.