| Amino resins used in the production of wood-derived materials. Part III. The effect of modifiers on the properties and structure of melamine-urea-formaldehyde (MMF) resins|
The following types of resins were prepared: melamine resins with a 1:3 mole ratio of melamine to formaldehyde, urea resins (from a few step reaction) with a 1:1.2 final mole ratio of urea to formaldehyde, and phenolic resins with a 1:1.4 mole ratio of phenol to formaldehyde. The melamine- urea-formaldehyde (MMF) resins were obtained either by mixing a non-distilled melamine resin with a distilled urea resin or by codistillation of a non-distilled urea resin with anon-distilled melamine resin. These MMF resins were modified by mixing them with phenolic resin and, additionally, with low-molecular-weight glycols,polyoxyethylenated glycols or e-caprolactam. In the case of modification with phenolic resins a codistillation of this resin with MMF resin was also conducted. The chemical structure of modified MMR resins was determined by the13C-NMR and mass spectroscopy methods. The effect of modification on the viscosity, density and pH-value of the compositions was characterized. The storage life of modified MMF at room temperature was significantly improved, particularly of those containing additional modifiers. The results of these investigations were applied to develop liquid adhesive compositions to be used for the manufacture of water-resistant ply wood and chipboard.
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