Synthesis and Study of Water based Acrylic Modified Polyester for Coating Metal Cans
Trimethylolpropane,neopentyl glycol,diethylene glycol,phthalic anhydride,isophthalic acid,adipic acid,fumaric acid,trimellitic anhydride,etc.were used as the main raw materials to synthesize a water-soluble polyester containing trace double bonds.Then,the water-soluble polyester is further copolymerized with styrene,butyl acrylate,hydroxypropyl acrylate and acrylic acid and other acrylate mixed monomers containing hydrophilic units to prepare an acrylic modified waterborne polyester resin.The performance differences of waterborne polyester before and after modification were compared and studied,and the physical and chemical properties of waterborne polyester for metal packaging cans coated with white codine coating and waterborne acrylic modified polyester for metal packaging cans were studied respectively.The effects of the dosage of unsaturated anhydride,the hydroxyl value of waterborne polyester,the dosage of grafted modified acrylate monomer,and the acid value and hydroxyl value of grafted modified acrylate monomer on waterborne acrylic modified polyester were discussed.The results showed that the grafting effect was the best when fumaric acid accounted for about 2%of the polyester intermediates.When the hydroxyl value of polyester intermediates and propionate monomers are in the range of 100 mg·g-1～120 mg·g-1(solid hydroxyl value),the hardness,flexibility and chemical shape resistance of the paint film are the best.When the acid value of waterborne acrylic modified polyester is 25 mg·g-1～30 mg·g-1(70%solid),the water solubility and storage stability are the best.When the dosage of grafted modified acrylate monomer is 1∶3 to the mass ratio of polyester,the paint film prepared by water-based acrylic modified polyester has excellent T-bending properties,adhesion and physicochemical properties,and can be used to prepare white codine coating on the outside of water-based cans.When the dosage of grafted modified acrylate monomer is 3∶1 to the mass ratio of polyester,the paint film prepared by waterborne acrylic modified polyester has excellent gloss,fullness,flexibility and excellent solvent resistance,and good storage stability,which can be widely used in the preparation of varnish coatings.
metal cans coatingacrylic modified polyesterglosssolvent resistanceflexibility
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