Abstract:
PROBLEM TO BE SOLVED: To provide a crack preventing agent for cardboard which is capable of improving crack resistance of cardboard represented by a ruled-line crack of liner base paper and a column crack of core base paper and imparting water resistance as well without a large reduction in strength.SOLUTION: The crack preventing agent for cardboard contains a dehydrated condensate obtained by dehydration and condensation of a trivalent or tetravalent carboxylic acid (a1) and at least one compound (a2) selected from the group consisting of 6-22C monovalent aliphatic alcohol (a2-1), and an aliphatic amine (a2-2) having a 6-22C alkyl group and/or an alkenyl group, and/or a salt thereof (A).