Experimental Determination of the Influence of Adhesives on the Formation of Natural Angles of Opening Book Blocks

For the production of book products of intensive and long-term use, providing durability and durability of adhesive joints of the roots of book blocks, seamed threads, creates grounds for observance of the basic indicators of operational reliability of the whole book edition. In order to take into account the peculiarities of the technological production of book products, it is necessary to take into account the main types of book destruction that arise during their long-term use. When the book block is sewn with threads, framed, with a glued paper ribbon, to the formation of the natural angles of opening the block, first of all, the own weight of the paper notebooks, from which the block forms, depending on the opening area of the book, its mass, density, thickness, stiffness, as well as the strength of adhesive fastening and ribbed edges. When sequentially turning pages of a book, due to a change in their volumes, the load on the root portion of the block and the roots of the cover change, which increases to the side of the overturning and decreases in the opposite direction. Changing the load on the root of the cover leads to a positional effect on the individual areas of the root of the cover, consistent during the successive flipping of the pages, or in areas that depend on the discrete block area. Such influence on radicular part of the cover reflects the gradual process of inflection in various areas of linear material behind that, over time, loses elasticity and integrity of the structure and ceases to function lock supporting movements for radicular part of the book block. An analysis of the research carried out on the formation of the maximum natural angle of opening of the book blocks, without the application of additional efforts directed at the deformation of the root portion, has revealed the composition of some types of adhesives that provide the maximum strength of root fixation and simultaneous high elasticity, which contributes to the maximum angle of opening of blocks with sewn threads and has applied value, when modeling book models, selecting technology for their production and applying modern bookbinding materials