Study on preparation and properties of urea-formaldehyde resin adhesive modified by phenol and acetylene-urea
The urea-formaldehyde resin is synthesized by using urea and formaldehyde as raw materials,and phenol and acetylene-urea as formaldehyde collectors.The content of free formaldehyde in urea-formaldehyde resin will decrease and the curing time of the resin will increase when the dosage amount of phenol and acetylene-urea increases.The content of free formaldehyde will drop and the viscosity of urea-formaldehyde resin will increase if polycondensation time prolongs.The content of free formaldehyde is 0.042 6％ in urea-formaldehyde resin prepared by the alkali-acid-alkali synthesis process under conditions that the mass content of phenol,acetylene-urea and melamine is 0.5％,0.5％,and 1％ respectively,the polycondensation time takes 20 min,formaldehyde is one off added,and urea and formaldehyde collectors are added in batches.The content of free formaldehyde is far below the El grade index of Zhejiang DB33-T-494 standard.
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