Abstract: A problem to be addressed by the present invention is to provide a primer for ink-jet printing inks, the primer being capable of preventing streaks from generating on a printed material, a recording medium, and a method for producing the recording medium. The present invention relates to a primer for ink-jet printing inks, the primer containing an aqueous medium and at least one vinyl polymer (A) selected from the group consisting of a vinyl polymer (A1) having a structural unit derived from an aromatic vinyl monomer and having a glass transition temperature of 50° C. to 100° C. and a halogenated vinyl polymer (A2) having a glass transition temperature of 50° C. to 100° C.

Abstract: The present invention provides a commercial transaction system which enables goods to be sold and bought with high accuracy without anxiety by using a computer network such as the Internet, and which can also give credit information in commercial transaction. The electronic commercial transaction system according to the invention includes plural electronic terminals connected to one another by a computer network, and an authentication station connected to the computer network. An electronic certificate and a company code are assigned to each of the electronic terminals on the basis of examination performed by the authentication station, and when a commercial transaction is to be performed between one and another of the electronic terminals via the computer network, both selling and buying sides of the commercial transaction present the respective electronic certificates before performing the commercial transaction.