Abstract: A retractable blade knife includes a body, a handle lever and a blade holder assembly. The blade holder assembly is mounted to the distal end of the body to pivot between a retracted position in which a cutting edge is concealed within the body and an extended position in which a cutting edge is exposed. The handle lever is mounted to the body at a pivot joint that is located between the opposite ends of both the lever member and the body so that the handle lever can pivot between an open position and a closed position. A pin at the distal end of the handle lever is received for sliding movement by a slot in the blade holder assembly so that when the handle lever is urged from the open position to the closed position, the blade holder assembly rotates from the retracted position to the extended position.

Abstract: The invention relates to a paste for surface sizing paper, containing an anionic optical brightener and a mixture comprising a cationic polymer dispersion and a cationic or amphoteric alkyl ketene dimer dispersion or emulsion as the sizing agent, and to the use thereof for surface sizing paper, and to the sizing method.

Abstract: A cationic dispersant composed of a copolymer made of the monomers N,N-dimethylamino acrylate and/or methacrylate, the acrylic acid ester and or methacrylic acid ester of a C.sub.10 to C.sub.22 fatty alcohol, methyl acrylate and/or methyl methacrylate, acrylic and/or methacrylic acid and optionally n-butyl acrylate and/or methacrylate and isobutyl acrylate and/or methacrylate. It is equally suitable for the production of stable sizing agent dispersions intended for internal or surface sizing.

Abstract: A cationic dispersant composed of a copolymer made of the monomers N,N-dimethylamino acrylate and/or methaacrylate, the acrylic acid ester and or methacrylic acid ester of a C.sub.10 to C.sub.22 fatty alcohol, methyl acrylate and/or methyl methacrylate, acrylic and/or methacrylic acid and optionally n-butyl acrylate and/or methacrylate and isobutyl acrylate and/or methacrylate. It is equally suitable for the production of stable sizing agent dispersions intended for internal or surface sizing.

Abstract: A process is provided for making an anionic polyurethane wherein a monomeric, aliphatic, dihydroxyl compound having an aliphatic substituent containing at least 10 carbon atoms is reacted with an organic polyisocyanate to form an adduct having terminal NCO groups, and the resulting adduct is reacted with an aliphatic monomeric diol chain extender containing an acid group which is capable of salt formation or a salt group. If the chain extender contains an acid group, the chain extended polyurethane is reacted with a basic compound to form a salt. The product of the invention may be used to size paper.

Abstract: Cationic polyurethanes and a process for their production wherein a polyisocyanate, preferably a diisocyanate such as 2,4- or 2,6-tolylene-diisocyanate is reacted with an aliphatic dihydroxy compound substituted with an aliphatic side-chain of at least 10 carbon atoms to form a preliminary adduct or so-called prepolymer with terminal -- NCO groups. This prepolymer is then reacted for chain-lengthening with an aliphatic monomeric diol (A) containing a tertiary nitrogen atom convertible into an ammonium compound or an aliphatic monomeric diol (B) containing a tertiary nitrogen atom already converted into an ammonium compound. The new cationic polyurethanes are especially useful as sizing agents for the sizing of paper.