Preparation Of Cyclic Carbonate Derivatives And Their Application In Non-isocyanate Polyurethane Coatings

Polyurethane coatings are widely used in coating industry owing to their excellent properties.However,to fabricate polyurethane coatings,one of important reagents that contains isocyanate unit is harmful to human beings and environment because of its toxicity.Therefore,the non-isocyanate polyurethanes?NIPU?which synthesized from cyclic carbonates with polyamines exhibit all the advantages of traditional polyurethanes and also display better and greener performances,making them a substitute for traditional PU.However,the current preparation of NIPU coatings also demonstrates some drawbacks,such as high temperature conditions for the curing of cyclic carbonates and amines,extensive use of organic solvents such as DMF,and the lack of functional and other technical problems.In view of this,this project developed four kinds of non-isocyanate polyurethane coatings.?1?The cyclic carbonate?EC-51?was synthesized with diglycidylether of bisphenol A?E-51?and CO₂.The EC-51 prepolymers?EC-51-P?bearing cyclic carbonate groups were prepared by the reaction of EC-51 and isophorone diamine?IPDA?,and the molar ratios of carbonate/primary amine were ranging from 10:1 to 10:6.Afterwards,E-NIPU coatings were obtained by curing EC-51-P with PEI at room temperature.The GPC results revealed that molecular weights of EC-51-P were ranging from 2000 to 3800 with a PDI of 1.30-1.55,and the molecular weights of EC-51-P increased with the increase of molar ratios of carbonate/IPDA.The resultant E-NIPU coatings displayed excellent glossiness,impact strength,flexibility,adhesion,and hardness properties.Besides,the E-NIPU coatings displayed excellent solvent resistance to toluene,xylene,alcohol and alkali,and they also have excellent thermal resistance properties with the temperatures at 5%weight loss(T_5%)of the coatings above 260°C.?2?To improve the chemical resistance properties of NIPU,we synthesized two cyclic carbonates,bisphenol AF?EC-AF?and perfluorooctyl cyclic carbonate?PFGC?via the reaction of two different diglycidyl ethers?bisphenol AF?E-AF?and perfluorooctyl glycidyl ether?PFGE?,respectively?.Then the cyclic carbonate with diamines was mixed according to the molar ratio of carbonate/primary amine=1.0 to synthesize a series of F-NIPU coatings.The F-NIPU coatings have good hydrophobic and oleophobic properties.In addition,their hydrophobic and oleophobic properties were greatly improved with increasing of the PFGC content.Their films contact angle of water,diiodomethane,and hexadecane were high up to106.7^o,80.2^o and 72.7^o,respectively.The surface of the F-NIPU coating was smooth and with0.43 of the surface roughness value?R_q?.The coating has a good oleophobic effect on edible oil and vacuum pump oil.At the same time,the coated portion of the tin plate after immersing in 10%NaCl solution for 500 h,indicating the excellent corrosion resistance.?3?The sorbitol-based cyclic carbonate?SC?was prepared via the reaction of sorbitol-based epoxy resin?SE?and CO₂.The succinic anhydride,o-phthalic anhydride,and maleic anhydride via the reaction of SC.The structures were characterized by ¹H-NMR and FTIR,all results showed that the anhydrides and hydroxyl react adequately to produce the carboxylic acid.Then cyclic carbonate was neutralized by TEA,followed by dispersing in water to obtain sorbitol-based aqueous cyclic carbonate dispersion.The results show that the particle sizes of the aqueous cyclic carbonate dispersion ranged from 63 to 174 nm with the Zeta potential from-73.3 to-48.2 mV.A series of waterborne nonisocyanate polyurethane?S-WNIPU?coatings were successfully prepared by reacting the aqueous cyclic carbonate dispersions with diamines.The S-WNIPU coatings exhibited excellent flexibility,adhesion,gloss,and impact resistance.The T_g of S-WNIPUs was in the range of 58.6°C-103.1°C.All the S-WNIPU coatings have excellent thermal resistance properties and their 5%weight loss temperatures(T_5%)were all above 246°C??4?Cyclic carbonates?TMC/PMDC/BTDC?were synthesized at an atmospheric pressure by reacting glycerine carbonate?GC?with trimellitic anhydride/pyromellitic anhydride/benzophenone-3,3?,4,4?-tetracarboxylicdianhydride?TMA/PMDA/BTDA?,respectively.Cyclic carbonates have 2.62,3.72 and 3.43 cyclic carbonate functional groups,respectively.TMC/PMDC/BTDC cyclic carbonates were neutralized by dimethylethanolamine and dispersed in water to prepare TMC/PMDC/BTDC aqueous cyclic carbonate dispersions.The dispersion particle sizes of aqueous cyclic carbonates ranged from 30 to 120 nm with the Zeta potential from-55 to-79.5 mV.At the same time,they exhibited no stratification after 5000r/min centrifugation for 60 min,indicating that the aqueous dispersions have good stability.A series of related waterborne nonisocyanate polyurethane?T-WNIPU,P-WNIPU and B-WNIPU?coatings were successfully prepared by reacting TMC/PMDC/BTDC aqueous cyclic carbonate dispersions with diamines.The WNIPU coatings exhibited excellent gloss,impact resistance,adhesion,flexibility and hardness.The WNIPU coatings all displayed excellent chemical resistance towards toluene,xylene,alcohol and 5%H₂SO₄.The T_g of WNIPUs was in the range of 31.4°C-100.2°C.All the WNIPUs coatings have excellent thermal stability and their 5%weight loss temperatures(T_5%)were all above 242°C.