Abstract: To effectively impart sizing performance to paper, while reducing the amounts of an internal sizing agent and aluminum sulfate, a papermaking additive comprises a mixture of an amphoteric copolymer having a hydrophobic group whose quaternization ratio is 40% by mole or more, and in which the ratio of the anion equivalent to the cation equivalent is 0.1 to 90%, and a calcium carbonate filler. The filler is one in which suitable water repellency is imparted to the filler. Hence, by adding this to pulp slurry, followed by a wet papermaking, the filler is efficiently adsorbed onto pulp fibers having anionic property, so that effective sizing performance can be imparted to the paper by using a smaller amount thereof than the internal sizing agent, while reducing the amounts of the internal sizing agent and the aluminum sulfate.

Abstract: The invention improves a sizing effect even on paper containing no internal sizing agent and improves productivity by making solution polymerization in a small amount of an organic solvent. The invention provides a cationic surface sizing agent composed of a copolymer obtained by solution polymerization of (a) 15 to 35% by weight of a tertiary amino group-containing monomer, (b) 30 to 85% by weight of C1 to C4 alkyl(meth)acrylate, and (c) 1 to 50% by weight of styrenes in an organic solvent in the presence of a chain transfer agent. The copolymer may be subjected to cationization treatment with a quaternization agent. As a constituent monomer of the copolymer, 0 to 20% by weight of another copolymerizable vinyl monomer (d) may be contained. The cationic surface sizing agent is applied to paper.

Abstract: To effectively impart sizing performance to paper, while reducing the amounts of an internal sizing agent and aluminum sulfate, the invention provides as a papermaking additive a mixture of a cationic copolymer having a hydrophobic group whose quarterization ratio is 40% by mole or more, or an amphoteric copolymer having a hydrophobic group which has the same quarterization ratio as above, and in which the ratio of the anion equivalent to the cation equivalent is 0.1 to 90%, and a filler (a pretreated filler). The pretreated filler is one in which suitable water repellency is imparted to the filler. Hence, by adding this to pulp slurry, followed by a wet papermaking, the pretreated filler is efficiently adsorbed onto pulp fibers having anionic property, so that effective sizing performance can be imparted to the paper by using a smaller amount thereof than the internal sizing agent, while reducing the amounts of the internal sizing agent and the aluminum sulfate.

Abstract: The invention improves a sizing effect even on paper containing no internal sizing agent and improves productivity by making solution polymerization in a small amount of an organic solvent. The invention provides a cationic surface sizing agent composed of a copolymer obtained by solution polymerization of (a) 15 to 35% by weight of a tertiary amino group-containing monomer, (b) 30 to 85% by weight of C1 to C4 alkyl (meth)acrylate, and (c) 1 to 50% by weight of styrenes in an organic solvent in the presence of a chain transfer agent. The copolymer may be subjected to cationization treatment with a quaternization agent. As a constituent monomer of the copolymer, 0 to 20% by weight of another copolymerizable vinyl monomer (d) may be contained. The cationic surface sizing agent is applied to paper.

Abstract: It is an object to improve sizing performance and anti-plate-soiling property in offset printing, for example, in a cationic surface sizing agent to be used for coating base paper of newsprint paper, and as a means for solving the object, a cationic surface sizing agent is produced by quaternizing a copolymer having a weight average molecular weight ranging from 30,000 to 60,000 obtained by polymerizing (a) 20 to 40% by weight of a monomer containing tertiary amino group; (b) 10 to 80% by weight of a C4 to C18 alkyl ester of (meth) acrylic acid; and (c) 0 to 70% by weight of a styrene or derivative thereof, using an azoic polymerization initiator in the presence of a chain transfer agent. In this manner, it is possible to improve sizing performance without reducing the hydrophobic level of copolymer and to suppress sensitization of printing plate such as PS plate by specifying the monomer composition ratio, using an azoic polymerization initiator, and specifying molecular weight of the copolymer.

Abstract: The invention provides a sizing agent with good stability, particularly which is rapid in getting started in the neutral zone and a method of producing the same.A sizing agent for papermaking in neutral zone is characterized by a main component of said sizing agent being selected from the group consisting of a diester of rosin-based substances having a dicarboxylic acid or acid anhydride group expressed by the following formula (I), ##STR1## (in which R.sub.1 represents a rosin acid residue or maleopimaric acid, R.sub.2 represents a dihydric alcohol residue and R.sub.3 represents a maleopimaric acid residue); and 2) a polyester reaction product expressed by the following formula (I'), ##STR2## (in which R'.sub.1 and R'.sub.5 represent a rosin acid residue or an .alpha.,.beta.-unsaturated polybasic carboxylic acid added rosin residue, at least one of them represents .alpha.,.beta.-unsaturated polybasic carboxylic acid added rosin residue, R'.sub.2 and R'.sub.4 represent polyhydric alcohol residues, R'.sub.

Abstract: The present invention relates to a size composition which shows an excellent sizing effect in neutral to weakly acidic papermaking.Alkanol tertiary amine and fortified rosin, incorporated in the size composition of the present invention, even when prepared as dispersions using a dispersant, are extremely poor in sizing performance in the neutral pH range, whereas the size composition obtained by mixing these components in a ratio according to the present invention and dispersing them using a surfactant specified by the present invention offers an excellent sizing in the neutral to weakly acidic pH range.