Method for producing binder resin, method for producing resin composition, binder resin, and resin composition

#The present invention relates to a method for producing a binder resin, a method for producing a resin composition, a binder resin, and a resin composition, and more specifically relates to a method for producing a binder resin used in coating application pastes, such as a conductive paste, and a binder resin.

#Multilayered electronic components, such as multilayer ceramic capacitors (MLCC) are rapidly increasing in capacity and becoming smaller in size.

#In MLCCs, a chip in which dielectric layers and electrode layers are alternately laminated is formed by alternately laminating multiple ceramic green sheets, which contain a high dielectric material, such as barium titanate, and multiple layers formed from a conductive paste containing mainly a conductive material, a binder resin and a solvent, and then drying and firing the obtained laminate. As MLCCs have increased in terms of capacity, there have been demands for an increase in the number of layers and a reduction in thickness of each layer, but this has led to a variety of production-related problems. Particular problems include insufficient film strength of electrode layers and insufficient adhesion to dielectric material sheets, which leads to the occurrence of defects and to peeling off of electrode layers from dielectric layer interfaces. In addition, as conductive materials become more finely particles dispersibility of the materials in binder resins is reduced, meaning that formed electrodes become non-uniform and obtained MLCCs readily suffer from problems such as reduced capacity and electrical short-circuits.

#Preferred aspects of the present invention will now be explained in detail. Moreover, numerical ranges indicated by the use of the symbol “-” in the present specification indicate ranges that include the numerical values mentioned before and after the symbol “-”. For example, “molar quantity of 2-15 times” means the range of molar quantity of not lower than 2 times and molar quantity of not higher than 15 times.

#Binder Resin

#A binder resin according to a preferred embodiment of the present invention is a resin that contains a reaction product of a cellulose derivative, a polyvinyl acetal and a bonding agent having, in the molecule, 2 or more functional groups which are able to react with hydroxyl groups in the cellulose derivative and the polyvinyl acetal. The content of the bonding agent is at least double the molar quantity of whichever has the greater number of moles between the cellulose derivative and the polyvinyl acetal. By having such a constitution, compatibility between the cellulose derivative and the polyvinyl acetal resin is increased, occurrence of phase separation and the like is suppressed in a resin composition, such as a paste, obtained using the binder resin, and the homogeneity of the resin composition and the homogeneity of a coating film formed from the resin composition are improved. In addition, by forming a polymer alloy of a cellulose derivative, which exhibits excellent printability, and a polyvinyl acetal, which exhibits excellent adhesive properties and mechanical strength, it is thought that it is possible to obtain a binder resin that exhibits both printability and film strength.