Лако-красочные материалы — производство

‘‘Insects, fish and birds know the art of producing mucous body fluids suitable for gluing. The load-carrying capacity of the hardened glue, as exemplified by egg-fastening and nest-building, is comparable to that of modern structural adhesives’’ [1, p. 1]. As human­kind evolved, inquisitive persons observed and thought about insect and bird building and repair of nests with mud and clay. They encountered spider webs and naturally occurring ‘‘sticky’’ plant and asphaltic materials that entrapped insects, birds, and small mammals.

Unlike species that use an inherited instinct to perform a single task, human beings adopted the techniques of many species. They observed the natural phenomenon of sticky substances, then gathered and used these materials in locations away from their origins, exemplified today by the recently discovered Stone Age natives of South America’s Amazon region and those in the interior of Borneo and New Guinea.

As rains fell, and then drying set in, many sticky materials regained their sticky properties, and some of the leaves used by ancient peoples to wipe sticky residues from their hands retained small quantities of water. Observing this, the first crude waterproof containers were manufactured using what we now call pressure-sensitive adhesives.

Our early ancestors used mud, clay, snow, and other natural materials to keep vermin, wind, and inclement weather out of their dens, warrens, caves, and other habitations. Today we use materials called sealants to perform similar functions in the construction and maintenance of modern buildings.

Straw and other vegetable material found its way into the muds and clays and reinforced them, forming the first crude composites. These materials later developed into bricks, which were in turn joined with the same or other materials used as mortars.

As human beings developed tools and weapons, sharp stones had to be fastened to handles to make axes and spears. Some of these were bound with vines, fibers, pieces of animal skin, or tendons or other body parts, and some had natural self-adhering proper­ties to supplement the use of knots. To enhance the joining process, observing users soon smeared on sticky materials found locally.

When some natural materials fell on rocks heated by the sun, they softened and became sticky, and later hardened in the cool of the night. Observers made use of these natural phase-change materials as they chanced upon them. When lightning started fires, some materials melted and then cooled in interesting shapes. Observers, using the fires to harden their sharpened stick weapons, put out the fires by rubbing their sticks on the ground, and some contacted and melted resins, which when cooled, again hardened. Thus was born the technology we now call hot-melt adhesives.

Some of the other materials used by early human beings as adhesives are now called beeswax, rosin, rubber, shellac, sulfur, tar, and vegetable gums. Later, as people developed bows and arrows, it was found that feathers fastened to an arrow shaft helped to stabilize the arrow’s flight. The same sticky or heat-softened materials soon supplemented the use of natural fibers to attach the feathers.

If Noah really did build an ark, the seams had to be sealed to keep out the water. And early human beings must have floated their possessions across bodies of water in bark or leaf containers with the seams sealed with sticky, waterproof materials.

Prehistoric peoples made pottery, and contrary to the Bible admonition in Jeremiah 19:11, ‘‘as one breaks a potter’s vessel, so that it can never be mended,’’ they often used rosin to reassemble broken vessels to retain food buried with the dead, as we know from remnants found in archaeological digs.

Bituminous cements were used to fasten ivory eyeballs in statues in 6000-year-old Babylonian temples, and combinations of egg whites and lime were used by the Goths 2000 years ago to fasten Roman coins to wood, bonds that remain intact today [2, p. ix]. ‘‘Bitumen was supposedly the mortar for the Tower of Babel; beeswax and pine tar were used in caulking Roman vessels that dominated the Mediterranean Sea’’ [3, p. 62]. ‘‘Plant gums and mucilage have been known and in use since very early times, reference being made to them in the Bible; they seem to have been of commer­cial value for several thousand years, especially in India, Asia, Africa, Australia, and China’’ [4, p. vii].

In historic times the Egyptians used crude animal and casein glues to laminate wood for bows and furniture, including wood veneers, many of which have endured to modern times in that dry climate. To make these products it is likely that they were familiar with the production of bonded abrasives in the form of sand bonded to papyrus or cloth with animal glue. They developed starch pastes for use in bonding papyrus to textiles and to bond leather, and a plaster of calcined gypsum identical to today’s plaster of Paris. Later the Greeks used slaked lime as a mortar, and both the Greeks and Romans mixed the lime with volcanic ash and sand to create a material still known as pozzolanic cement. This was used in the construction of the Roman Pantheon and Colosseum. Thus was born the rude beginnings of the art and science we now call adhesive bonding technology.