Effect of high acid value components on the properties of two-component dry-blended matting polyester resin for thermal transfer

Chen Cheng, Li Yong, Xie Jing, Liu Liang, Sun Junfang, China Electric Science Research Institute Co., Ltd., Guangzhou Dynasky Materials Technology Co., Ltd.
Summary: Studied the effects of acid-alcohol ratio, TMA content, sulfate content and high-low acid resin quality ratio on the performance of two-component dry mixed polyester resin for thermal transfer. The results showed that with the improvement of acid-alcohol ratio and TMA content, the gloss of the two-component anti-light coating continued to decrease and the thermal transfer performance continued to improve;
Prove
In recent years, with the continuous increase of national environmental protection efforts, powder coatings as environmentally friendly coatings have been more and more widely used, the emergence of home appliance powder coatings, furniture powder coatings, pipe anti-corrosion powder coatings, high-speed guardrail powder coatings and other professional coatings .
transfer technology is a process applied to the printing and decoration of ink pattern patterns on the surface of materials, which is efficient, economical, stable and rich in patterns. In recent years, the application of thermal transfer technology in powder coatings has developed rapidly, and has been widely used in home appliances, aluminum profiles, anti-theft doors and windows and other fields. However, the current thermal transfer powder coating is mainly high-gloss type (such as dynamite NH3295), less anti-light products, and the existing dry mixed anti-light resin varieties (such as dynamite NH8081/NH8588) although the light-absorbing performance is excellent, but the transfer effect is not good. Therefore, the development of low-light powder coatings suitable for thermal transfer has a large market space.
From the point of view of polyester resin synthesis, this paper studies the effects of acid-alcohol ratio, TMA content, radon sulfate dosing and high-low acid resin quality ratio on the performance of two-part dry-mixed anti-light powder coating in thermal transfer.
Test Part
1.1 Raw materials
NPG, industrial grade, bp), glycol (EG, industrial grade, bp), trihydroxymethyl propane (TMP, industrial grade, bp) to benzoic acid (PTA, industrial grade, Basf), interphenyl xylene (PIA, industrial grade, kp), parabens (PIA, industrial grade, kp) TMA, industrial grade, Basf), catalyst F4100 (industrial grade, domestic), antioxidant 1076 (industrial grade, Basf), antioxidant 168 (industrial grade, Basf), tribenzene ethyl bromide, isocyanuric acid triglycerides (TGIC), thioic acid, titanium dioxide powder, resting fragrance, leveling agent, are domestic, industrial grade.
1.2 polyester resin sample preparation
first of all, the formulation of the amount of polyic acids, polyols, catalysts, etc. added to the reactor, from 180 to 240 degrees C under the protection of N2 slowly heating up, to reach a clear point, add the acid solution 3h, and then vacuum shrink 2h, to achieve the target acid value, viscosity, add antioxidants, materials. The acid value of the high acid resin sample is controlled at 50 to 60 mg KOH/g, the viscosity is controlled at 4000 to 5500mPa.s (200 degrees C);
1.3 Preparation process for powder coatings and coatings
according to the formula of Table 1 to 2 to prepare the required powder coating, the basic process is: ingredients, premixed, extruded, pressed, crushed, sifted, sprayed, cured, wherein the curing condition is 200 degrees C x 10min.
1.4 thermal transfer test for powder coatings
mixes two powder coatings with high and low acid values in proportion to a mass ratio of 1 to 1, and then sprays them on the transfer board at 180 to 200 degrees C Curing 10min, after curing the transfer board placed on the transfer machine, spread the transfer paper, transfer 2min at 200 oC, transfer paper after the transfer will be torn off, you can get the transfer plate printed with the transfer pattern.
1.5 sample detection and symptoms
glass transition temperature (Tg) of polyester resin synthesized by metler DSC-1 differential scanning thermometer test; and surface appearance of the coating using Guangzhou Meimei Photoelectric MP-41 polarizing microscope.
Results and discussion
2.1 Effect of high acidic acid ratio on the performance of two-part dry mixed anti-light resin for thermal transfer
Table 3 shows the acid value, viscosity, and Tg results of the high acidity of different alicic acid ratio. The acid value increased from 32.1mgKOH/g to 60.8mg KOH/g, the viscosity was controlled from 4500 to 5000mPa.s, and the resin Tg was between 64 and 69 degrees C.
1 shows the effect of the high acid-value resin-alcohol ratio on its reactivity and dry-mixed anti-gloss coating gloss. It can be learned that with the increase of acid-alcohol ratio, the reaction time of the high acid content is gradually shortened, the curing speed is gradually accelerated, and the gloss of the two-part anti-light plate is gradually reduced. This is due to the increase in the alcohol-acid ratio to improve the acid value of the resin, thereby increasing its reaction activity, the reaction is shortened. The increase of high acid reaction activity widens the reaction activity difference of high and low acid value, and increases the roughness in the coating curing process, thus reducing the gloss of the light-depressing plate.
2A, B, C and D are transfer effect pictures with acid-alcohol ratios of 1.04, 1.06, 1.09, and 1.12, respectively. It can be learned that with the increase of acid-alcohol ratio, the transfer effect of the anti-light plate surface gradually becomes better. When the acid-alcohol ratio is 1.04, most of the transfer paper and the coating surface bonded together, the board effect is poor, when the acid-alcohol ratio reached 1.12, the transfer paper and the coating surface completely fell off, the coating surface showed a better transfer effect. This is due to the increase of acid-alcohol ratio, resin activity gradually increased, resin curing degree increased, in the transfer process, after curing degree is small, not easy to bond with the transfer paper, so gradually obtained a better transfer effect.
effect of the 2.2 TMA content on the performance of the two-part dry mixed anti-light resin
Table 4 is the basic performance parameter of the high acid resin obtained from different TMA content. It can be seen that the synthetic resin is 90/10 type, the acid value is basically between 50 to 53 mg KOH/g, viscosity between 4500 to 5000mPa.s. The Tg of the resin does not change much, and fluctuates basically within the (69-1) degrees C.
3 shows the effects of different TMA contents on resin reactivity and coating gloss. It can be seen that with the increase of TMA dosage, the reaction time of the resin is gradually shortened, because TMA, as the sealing monosome of the resin, is at the end of the resin molecular chain, providing the resin with a niobine base for cross-link curing, which is more active and easier to react with the curing agent than the IPA sealing end, thus improving the reaction activity of the resin. At the same time, with the increase of reaction activity, the activity difference between high acid resin and low acid resin increases, so the gloss of the coating is gradually reduced.
4 is a photo of the thermal transfer of the resin coating obtained from different TMA content. Figure 5E and F are the polar microscope photos at the red boxes of Figure 4A and C, respectively. As can be seen from Figure 4, with the increase of TMA content in high acid resin, the thermal transfer effect of dry mixed anti-light coating gradually becomes better. Comparing Figures 5E and F, it can be seen that the coating surface with poor transfer effect has fibrous material residue, which may be due to the resin curing later resulting in the bonding of the transfer paper. Figure 5F resin due to the fast curing speed, the transfer process did not have a post-curing process, so as to achieve a better transfer effect.
2.3 Effect of the content of vanadium sulfate on the performance of the dry mixed anti-light resin
Figure 6 shows the effect of the different sulphate content of the high acid components on its gel time and the gloss of the dry mixed anti-light coating. It can be seen that with the increase of the content of radon sulfate, the gel time of the high acid content is shortened and then longer. This shows that the appropriate amount of niobium sulfate is conducive to promoting the curing crosslink of high acid resin, but the dosing is not conducive to the resin curing reaction. From Figure 6, it can also be seen that the gloss of the dry mixed anti-light coating is inversely related to the content of nicotospheric sulfate, the greater the amount of nicotic acid, the lower the gloss. Figure 7 shows the effect of different sulfate content of high acid components on the thermal transfer coating of the dry mixed anti-light coating. It can be learned that, with the increase in the amount of sulphate, the thermal transfer effect of the dry mixed anti-light coating becomes better, this aspect is due to the addition of nicosal sulfate to promote cross-linking reaction, improve the cross-link density of the coating, so that the thermal transfer effect is better; However, excessive sulfate has a negative effect on thermal transfer, the optimal addition is about 25%.
2.4 Effect of high and low acid value ratio on the performance of dry mixed anti-light coating
Figure 8 shows the effect of different high and low acid-value resin quality ratio on the gloss of dry mixed anti-gloss coating. It can be seen that with the increase of the high and low acid value resin quality ratio, the coating gloss shows a tendency to decrease first and then increase, when the high and low acid value quality ratio is 1:1, the coating gloss is the lowest.
9 shows the effect of different high and low acid value quality ratio on the thermal transfer performance of dry mixed anti-light coating. It can be learned that with the increase of the high and low acid value resin quality ratio, the thermal transfer performance of the coating gradually becomes better, which is due to the high acid resin relative to the low acid resin has a higher cross-link density, and with the increase of the high acid resin dosing, the average cross-link density of the dry mixed anti-light coating increases, so that its thermal transfer performance becomes better.
In conclusion
Through the above research, it is found that improving the curing crosslink density of high acid polyester resin is an effective way to improve the thermal transfer performance of dry mixed anti-light coating, by increasing the acid-alcohol ratio of high acid components, adding three-function group monomer and so on. In addition, by expanding the high and low acid value activity difference, can reduce the gloss, when the high and low acid value mass ratio of 1:1 dry mixed light plate gloss is the lowest.
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