Aqueous ink compositions containing anti-curl agents

A process for reducing paper curl in plain-paper printed elements consisting essentially of the step of applying an ink composition to a plain-paper substrate, said ink composition comprising an aqueous carrier medium, a colorant and at least one anti-curl agent in an amount sufficient to substantially eliminate curl in said plain-paper substrate, wherein the anti-curl agent has a solubility in water of at least 4.5% at 25.degree. C. and is selected from the group consisting of:

• (a) 1,3-diols, 1,3,5-triols, amino-1,3-diols and polyoxyalkylene derivatives thereof having the following structure:
• ##STR5## wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 and R.sub.6 are independently H;
• C.sub.n H.sub.2n+1, where n=1-4;
• or C.sub.n H.sub.2n O(CH.sub.2 CHYO).sub.b H where n=1-6 and b=0-25;
• R.sub.3 =H;
• C.sub.n H.sub.2n+1 where n=1-4;
• C.sub.n H.sub.2n O(CH.sub.2 CHYO).sub.b H where n=1-6 and b=0-25;
• or (CH.sub.2).sub.e NXZ, where X and Z are independently H, CH.sub.3, C.sub.2 H.sub.5 or C.sub.2 H.sub.4 O(CH.sub.2 CHYO).sub.d H, where d=0-25 and e=0-3;
• Y=H or CH.sub.3 ;
• a and c are independently 0-25;
• and
• wherein the total number of CH.sub.2 CHYO units is 0-100;
• (b) polyols and oxyalkylene derivatives thereof having the following structure:
• ##STR6## wherein R is independently H, C.sub.n H.sub.2n+1, where n=1-4 or CH.sub.2 O(CH.sub.2 CHYO).sub.e H;
• Y=H or CH.sub.3,
• b=0 or 1;
• a, c, d and e are independently 0-40,
• f=1-6;
• and
• wherein the total number of CH.sub.2 CHYO units is 0-100;
• with the proviso that when a, b, c and d=0, and f=1, R is not H and when a, c, and d=0 and b and f=1, then R is CH.sub.2 O(CH.sub.2 CHYO).sub.e H and e is not 0;
• (c) compounds having the following structure:
• ##STR7## wherein X=H;
• OH;
• CH.sub.2 O(CH.sub.2 CHYO).sub.a H;
• O(CH.sub.2 CHYO).sub.b H;
• or OM where M is a metal cation;
• n=2-7;
• R=(CH.sub.2 CHYO).sub.c H, where Y=H or CH.sub.3 ;
• a, b and c are independently 0-25;
• and
• wherein the total number of CH.sub.2 CHYO units is 0-125;
• (d) pyranosides and polyalkoxyalkylene derivatives thereof having the following structure:
• ##STR8## wherein R=H or C.sub.n H.sub.2n+1, where n=1-4 a, b, c and d are independently 0-30;
• Y=H or CH.sub.3 ;
• and
• wherein the total number of CH.sub.2 CHYO units is 0-120;
• (e) poly (oxyalkylene) compounds having the following structure:
• H--(OCH.sub.2 CHY).sub.x OH
• wherein Y=H or CH.sub.3, and
• x=3-20;
• and
• (f) polyoxyalkylene derivatives of aliphatic polyamines having the structure:
• Z.sub.1 Z.sub.2 N(CH.sub.2 CH.sub.2 NZ.sub.3).sub.n Z.sub.4
• wherein Z.sub.1, Z.sub.2, Z.sub.3, or Z.sub.4 are independently (CH.sub.2 CHYO).sub.a H wherein Y=H or CH.sub.3 ;
• n=1-20;
• a is independently 0-20;
• and
• wherein the total number of CH.sub.2 CHYO units is 3-200.