Water soluble resins and application thereof to paper coating

A water soluble resin which is formulated by a method comprising:

• reacting at least a polyamine (a) selected from the group consisting of alkylene diamines and polyalkylene polyamines with at least one urea compound (b) to obtain a reaction product;
• and
• reacting said reaction product with a cross-linking compound (c) selected from the group consisting of alkylene glycol diglycidyl ethers, polyoxyalkylene glycol diglycidyl ethers, aromatic diglycidyl ethers, trimethylol propane triglycidyl ether, sorbitol diglycidyl ether, sorbitol triglycidyl ether, sorbitol tetraglycidyl ether, sorbitol pentaglycidyl ether, sorbitol hexaglycidyl ether, pentaererythritol diglycidyl ether, pentaererythritol triglycidyl ether, pentaererythritol tetraglycidyl ether and isocyanates having at least two isocyanato groups in a molecule,
• wherein the amount of the cross-linking compound is within a range of about 0.2 to 1 mole based on 1 mole of the polyamine (a).