Low viscosity unsaturated polyester resin with reduced voc emission levels
A polyester resin, unsaturated technology, used in the field of low viscosity unsaturated polyester resins with reduced VOC emission levels, which can solve problems such as reduced resin suitability
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Embodiment 1
[0016] Propylene glycol, diethylene glycol, oxalic acid dihydrate, zinc acetate dihydrate, and polyethylene terephthalate (PET) were added to an empty reaction vessel with stirring, following a general procedure for the preparation of unsaturated polyester resins. If the pressure can be maintained, the reactor is sealed and heated to 227°C to 238°C. If the reactor cannot be pressurized, keep the contents of the reactor at a constant temperature so as to maintain reflux until the PET is completely decomposed and digested. The reaction mixture became clear indicating the breakdown of PET. Upon completion of the decomposition digestion of PET, the reaction mixture was cooled to 177°C. At this point the maleic acid and maleic anhydride are added to the vessel. The reaction mixture was heated to 204°C to 210°C and the reaction was monitored in terms of acid value (AV) and viscosity until a predetermined value was reached. Once the reaction is complete, the newly formed unsaturat...
Embodiment 2
[0017] Embodiment 2 (transesterification reaction under atmosphere)
[0018]The unsaturated polyester resin prepared according to the method of Example 1 was reacted with methanol (50 moles) at 60° C. under atmospheric pressure. The unsaturated polyester resin contained propylene glycol (337 moles), diethylene glycol (40 moles), ortho Phthalic anhydride (161 moles), recycled polyethylene terephthalate (equivalent to 161 moles terephthalic acid / ethylene glycol half ester), and maleic anhydride. The reaction was monitored by measuring the viscosity of the unsaturated polyester resin reaction product. This unsaturated polyester resin has a viscosity of 1200 centipoise (cps) prior to reaction with methanol At 25[deg.] C., it was measured as 70% by weight solid dissolved in styrene. After transesterification, the viscosity of this unsaturated polyester resin is 500 cps At 25[deg.] C., it was measured as 70% by weight solid dissolved in styrene. Gas chromatography analysis r...
Embodiment 3
[0019] Embodiment 3 (transesterification under pressure)
[0020] The unsaturated polyester resin prepared according to the method of Example 1 was reacted with a mixture of ethanol (6.9 moles) and methanol (6.9 moles) under pressure at 210 ° C. The unsaturated polyester resin contained propylene glycol (60 moles), di Glycol (7.1 moles), recycled polyethylene terephthalate (equivalent to 28.6 moles terephthalic acid / ethylene glycol half ester), maleic anhydride (2.7 moles). The alcohol mixture was pumped in at a rate such that the pressure in the reaction vessel was maintained at 50 psi below the safety membrane rating. The reaction was monitored by measuring the viscosity of the unsaturated polyester resin reaction product. This unsaturated polyester resin has a viscosity of 1300 centipoise (cps) prior to reaction with the alcohol mixture At 25[deg.] C., it was measured as 70% by weight solid dissolved in styrene. The net polyester acid value was 27 mg KOH / g resin. Aft...
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