The development process of adhesives has those

2020-03-10 18:19

Adhesive is a medium used to bond objects together. It can bond different materials or the same material such as metal, glass, ceramics, wood, paper, fiber, rubber, and plastic into one body, giving each object its own application function.
People have a long history of using adhesives. According to archaeological excavations, as far back as 5300 years ago, humans mixed water and clay to bond solid objects such as stones into household utensils. 4000 years ago, China used raw lacquer as an adhesive and coating to make utensils, which is both practical and of technological value. In the Zhou Dynasty 3000 years ago, animal glue was used as a caulking sealant for wooden ships. In the Qin Dynasty, the mortar made of glutinous rice paste and lime was used as an adhesive for the cornerstone of the Great Wall, making the Great Wall still stand in the north of Asia and become a symbol of the ancient civilization of the Chinese nation. In 200 BC, the coffin sealant made of glutinous rice paste in China, combined with preservatives and other measures, not only prevented the body from decaying, but also kept the muscles and joints elastic when the coffin was unearthed more than 2000 years later, making it a sensation in the world. The ancient Egyptians extracted acacia from acacia trees, bone glue from bird eggs, and animal bones. They collected pine resin from pine trees to make adhesives. They also mixed clay with bone glue, and added pigments to seal and decorate coffins.
In ancient weapons manufacturing, both China and Japan used bone glue to bond armor and scabbards, and to make composite materials such as bows that were both flexible and elastic. Both ancient Rome and China have long known that using resin mucus to capture birds, and using bone glue to bond ink made of lampblack (or carbon black), played a significant role in the cultural development history of our country. As for the adhesive properties of blood found in hunting activities, there is also a long history. So far, pig blood and old flour still occupy an important position in China's construction and furniture manufacturing.
With the development of the economy, the demand has gradually increased, and the production of adhesives has developed from a decentralized manual workshop IfIJ r. In 1690, the Netherlands first established a factory for the production of natural polymer adhesives. In 1700, the United Kingdom established a factory mainly for the production of bone glue. In 1808, the United States established the first adhesive factory. In the 19th century, Switzerland and Germany sold casein, an adhesive extracted from cow's milk. In the 19th century, a salt made of casein and lime dust was used to make solid adhesives. During the First World War, it was also used to make small aircraft. Before and after the World War, except for casein, blood fibrin and soy protein once occupied a dominant position. At the same time, the United States used ginseng starch for plywood production, It is found to be much cheaper than using bone glue.
In summary, early adhesives were made from natural materials, and most of them were water-soluble. However, since the 20th century, due to the development of modern industries, natural adhesives have been unable to meet the requirements in terms of both production and variety, which has prompted the emergence and continuous development of synthetic adhesives.
The production of synthetic resin adhesives began with the invention of industrial phenolic resin by Baekeland in 1909. In 1912, plywood bonded with phenolic adhesives appeared, greatly reducing production costs, and improving the durability and adhesive strength of the plywood.
During the Second World War, due to the needs of the military industry, adhesives also underwent corresponding changes and development, especially in the application of adhesives to aircraft structural components, resulting in the emergence of the new name "structural adhesive". "Phenolic polyvinyl acetal resin mixed structural adhesive, brand name" Redux ", invented by Aero Company in the UK in 1941, was used for the bonding of main wings of fighter jets in July 1944 and achieved success.". Later, it was used in the manufacture of another aircraft called "comet", but soon the aircraft unfortunately crashed, causing a great disturbance. However, in tracing the cause of the accident, it was found that the cause of aircraft damage was fatigue and fracture of the metal, while the adhesive portion was still intact. Therefore, the credibility of adhesives has greatly increased, and their application in structural components has become more widespread.
Epoxy resin adhesives began to appear in the 1950s. Compared with other adhesives, they have the characteristics of high strength, multiple types, and strong adaptability, becoming the main structural adhesive. In recent decades, they have been widely used in the fields of household appliances, automobiles, water conservancy, transportation, electronics, and aerospace industry. Rubber based adhesives are also widely used in the shoe and automobile manufacturing industries. Before World War II, solvent based natural rubber accounted for the majority. Since the advent of neoprene adhesives in 1932, synthetic rubber adhesives have gradually taken the mainstream, and their combination with epoxy or other resins has greatly expanded the scope of application. In the wood making, paper processing, and packaging industries, polyvinyl acetate latex occupies a leading position. It is an excellent water-soluble adhesive. In most departments, it can replace traditional natural adhesives such as casein and bone glue. In 1943, Germany developed a polyurethane resin based on the high reactivity of isocyanates. More than a decade later, its adhesives emerged and were used in industries such as footwear, textiles, and packaging. These adhesives have the characteristics of high strength and good elasticity.
In 1957, the cyanoacrylate adhesive invented by Eastman Company of the United States ushered in a new era of instant bonding. Under normal conditions without solvents at room temperature, strong binding can occur within seconds to tens of seconds. In addition, there are anaerobic adhesives that isolate air and cause adhesion. In the 1960s, hot melt adhesives began to appear. Recently, reactive and radiation curable hot melt adhesives appeared. In the 1970s, there was a second generation of acrylate adhesives, followed by a third generation of acrylate adhesives. After the 1980s, the research on adhesives mainly focused on modifying the original varieties, improving their performance, improving their operability, developing suitable coating equipment, and developing non-destructive testing technology.