Study on Synthesizing Saturated Resin for Powder Coatings from Polyester Waste

Abstract:
a new process for degradation of recycled waste polyester (PET) bottles, with the degradation product benzoic acid (TPA) as the main reactant, polymerized into a powder coating saturated resin.
results show that the recovery rate of
degradation product TPA is 97%, the polymerization reaction temperature is 220 degrees C, the appearance of the product color is the best, the viscosity is 0.20/Pa.s, vika softening point temperature reached 48 degrees C.
saturated resin for synthetic powder coatings using PET recycled waste as raw material degradation, with good economic benefits and environmental protection effects

.years, China produces about 400,000 tons of polyester (PET) waste plastic each year, and the consumption of bottled polyester (PET) will increase to 3 million tons, which not only pollutes the environment, but also wastes resources. Therefore, the study of PET degradation reaction and the reuse of its products has become a hot topic of current research.
, the treatment method of waste PET in foreign countries mainly uses chemical method, which has a long route and high energy consumption. Domestic treatment of waste PET is mostly physical methods to prepare low value-added products, this method is simple to operate, low cost, but the regenerative materials of the decline in the performance of the regenerative properties, so that the recovery value of waste PET greatly reduced.
This study uses a new process of chemical degradation of recycled waste polyester (PET) bottles to polymerize the degradation products into saturated polyester resins for powder coatings with raw materials such as benzoic acid and neo-glycol, providing some basic data for the industrial production of saturated polyester resins prepared with waste PET as raw materials.. 1. Experimental part (1) the main raw materials
reclave PET waste (farmer mountain spring brand mineral water bottle), sodium hydroxide, glycol, thick sulfuric acid, new glycol, trihydroxymethyl propane, methylphenidate, interbenzene, hexate, zinc acetate are pure analysis.(2) Test method(1) degradation of PET waste
according to a certain ratio of PET fragments, zinc acetate, glycol into a three-mouth bottle, heating control temperature in 190 to 200 degrees C, to be reaction 2h after cooling to 110 degrees C, and several times added a certain proportion of sodium hydroxide.
heating up to 140 degrees C reaction 40min, poured into the beaker, diluted with the appropriate amount of warm water, and added 30% sulfuric acid regulation solution is acidic, with the cloth funnel vacuum filtration, loaded into the surface dish in 100 degrees C dry 12h or more to get white powdered TPA.(2) saturated resin synthesis
according to a certain ratio of new glycol, trihydroxymethyl propane into a three-mouth bottle, adjust the temperature to 190 degrees C, after complete melting into TPA several times, when the liquid in the bottle is transparent insulation 2h, add hexic acid heating up to 240 degrees C, after the reaction 30min to cool down to 230 degrees C.
add a certain amount of methylphenidate, heat up to 240 degrees C reaction 2h after decompression distillation 40min, cool down to 225 degrees C to add a moderate amount of additives, insulation 15min, poured into the mold cooling to get saturated resin.(3) Product Detection
peak analysis using the FT-IR EQUINOX55 Fourier Transform Infrared Spectrometer, the XLY-II capillary rheometer for viscosity determination, and the XWB-300C thermal deformation Vika softening point temperature determination.. 2. Results and discussion (1) ANALYSIS of the factors affecting the TPA yield of PET degradation products
As can be known from Figure 1, with the increase of sodium hydroxide dosing, when the amount of sodium hydroxide reached 36g, the amount of sodium hydroxide exceeded 3% of the theoretical value, the TPA yield reached 97%, continued to increase its dossing, TPA yield changed little, indicating that BHET and low polypolymers have been fully decomposed.(2) INfrared map of PET degradation product TPA
as can be known from Figure 2, O-H telescopic vibration at the wide peak in the 3066-2555cm-1 zone; For C-O telescopic vibration; 1686cm-1 near the strong peak, indicating that the molecule contains conjugated with benzene ring C-O;
another 732 to 938cm-1 for benzene ring absorption, 732cm-1 for benzene ring on the pair of ii replacement, indicating that the recovered substance is benzoic acid.(3) Effect of polymerization reaction conditions on the performance of saturated resin products (1) Effect of reaction temperature on the color of synthetic saturated resin
If the recovery product is not pure, the occurrence of side reactions such as oxidation cracking affects the quality of the product. This test is suitable for polymerization reaction temperature of 220 degrees C, synthetic saturated resin color is white, the color is the best.(2) Effect of vacuum decompression distillation time on the viscosity of synthetic saturated resin
As can be known from Figure 3, the viscosity of saturated resin increases with the increase of vacuum decompression distillation time, and when the polymerization reaction is complete, its viscosity does not change much.
vacuum, shorten the high temperature reaction time, reduce the end-base of the carboxylization, the appearance of the product gradually increased viscosity, resulting in a higher molecular weight and high-quality polyester resin. The vacuum decompression distillation time of this test is more suitable for 40 minutes. (3) Effect of reaction time on the softening temperature of vika, a synthetic saturated resin
As can be known from Figure 4, with the increase of reaction time, the more complete the reaction between reactants, the higher the softening temperature of Vika. In order to achieve the effect described by comparison, the powder coating special saturated resin produced by Wuxi Juwang Plastic Materials Co., Ltd. was measured by vika softening temperature, and the value obtained was 52 degrees C.
And the average Vika softening temperature of this test synthetic saturated resin is 48 degrees C, the difference between the two is only 4 degrees C, while other major performance basically conforms to the enterprise general purpose powder coating saturated resin product standards, can replace similar products. (4) polymer product saturated resin infrared spectral map
as can be known from Figure 5, 3431cm-1 is the telescopic vibration multiple frequency absorption peak of C-O;
1700 to 1600cm-1 (C-C telescopic vibration) did not appear medium-intensity absorption peak, 3095 to 3300cm-1 (double-key side C-H telescopic vibration) did not appear medium-strength absorption peak, indicating that the polymer product does not have dual-bond existence, that is, saturated resin.
the secondary synthesis of TPA recovered with PET degradation, which contains some impurity compositions. . 3.Conclusion
(1) Waste polyester (PET) degradation process TPA recovery rate of 97%, polymerization reaction temperature of 220 degrees C, the product appearance color is the best; (2) with waste PET recycling materials as raw materials, degraded, polymerized synthetic powder coating with saturated resin, its process is simple, efficient, stable quality, not only can reduce environmental pollution, but also can save resources, develop circular economy, with good economic benefits.
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