Method for making paper with improved filler retention and opacity while maintaining wet tensile strength

A method of making paper with improved filler retention and opacity is disclosed. The method includes adding Additive A and Additive B to the slurry in the wet part of a paper machine， wherein the slurry comprises pulp and filler. Additive A is a wet strength enhancer. Additive B is an anionic polymer having a charge density of about -3000 to about -7000 ueq/g on a dry matter basis， as measured in a buffer solution of about pH 6. Additive B also has a weight average molecular weight of about 150，000 to about 1，000，000 Daltons. A process is disclosed for making paper having improved filler retention and opacity. The process includes the step of adding Additive A and Additive B to a slurry in a wet end of a paper machine wherein the slurry comprises pulp and a filler. Additive A is a wet strength agent. Additive B is an anionic polymer having a charge density from about -3000 to about -7000 ueq/g on a dry basis when measured in a buffer having a pH of about 6. Additive B also has a weight average molecular weight of from about 150，000 to about 1，000，000， Daltons. A process is disclosed for making paper having improved filler retention and opacity. The process includes the step of adding Additive A and Additive B to a slurry in a wet end of a paper machine wherein the slurry comprises pulp and a filler. Additive A is a wet strength agent. Additive B is an anionic polymer having a charge density from about -3000 to about -7000 ueq/g on a dry basis when measured in a buffer having a pH of about 6. Additive B also has a weight average molecular weight of from about 150，000 to about 1，000，000， Daltons.