| 摘要 |
A printing ink is disclosed. The ink comprises (a) a reactive resin combined with a second resin comprising a substantially anhydrous water-soluble thermosetting stable methylated urea-formaldehyde resin wherein the weight of the methoxyl substituents therein is between 28% and 40% of the weight of the resin and the molar ratio of the reacted formaldehyde in the resin to the methoxyl substituents is such that in the absence of organic solvent the resin at 25 DEG C. is soluble to the extent of at least 50% by weight in water and dissolves at least 50% of its weight of toluene, the polymeric form of the resin being not substantially in excess of tetrameric, the molar ratio of reacted urea to reacted formaldehyde in the resin and the molar ratio of reacted formaldehyde to reacted methanol therein being within the ranges: }Molar ratio }Ranges Urea :CH2O :CH3OH CH2O :CH3OH }Lower 1 2.2 1.3 1 1.10 }Upper 1 2.8 2.0 1 2.15 } AND THE RESIN CONSISTING ESSENTIALLY OF <IMAGE> units, -CH2 bridges between the units, and -H, -CH2OH, and -CH2OCH3 substituents; and (b) a pigment.
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