In binding and finishing, a book-like device used to hold a quantity of paper sheets, commonly loose-leaf paper. Binders can either be temporary or permanent, the former allowing the easy removal and insertion of sheets, the latter not. Binders come in all shapes and sides, but there are a few standard sizes available. Binding mechanisms can include three-ring and post binding. See Mechanical Binding.
In printing ink manufacture, any substance in an ink that allows the ink pigment to adhere to the substrate, or printed surface, or to keep the pigment uniformly dispersed in the fluid ink vehicle. Some printing processes require specially formulated binders to enable the ink to adhere to the substrate properly. Various types of resins are used as binders. (See Resin and Ink: Printing Requirements.)
The term binder is also used in papermaking to refer to an organic or inorganic material added to the pigment in the manufacture of coated paper that assists the pigment particles in adhering to the paper fibers. Organic binders include starch, casein, and soya protein. Starch is the most widely used, and is obtained from a variety of agricultural sources, such as corn, wheat, potatoes, etc. Higher-quality papers use synthetic binders, typically styrene-butadiene and vinyl acrylic latices, which allow for greater gloss, ink holdout, and flexibility in post-printing operations such as folding and binding. (See Coating.) Binders are also known as adhesives.