What are Some Different Types of Adhesives?

Is a substance with good adhesion properties. Through the adhesion and cohesion from the surface adhesion to play the role of connecting objects. ^[1]

Organic or inorganic, natural or synthetic substances that can connect the same or two or more homogeneous or heterogeneous parts (or materials) together with sufficient strength after curing, collectively referred to as adhesives or Adhesives, adhesives, and conventionally referred to as glue.

Divided into natural polymer compounds (starch, animal skin rubber, bone glue, natural rubber, etc.), synthetic polymer compounds (epoxy resin, phenolic resin, urea resin, polyurethane and other thermosetting resins, polyvinyl acetal, perchloroethylene resin, etc. Thermoplastic resin, and synthetic rubber (such as neoprene, nitrile rubber), or inorganic compounds (silicate, phosphate, etc.) According to the requirements of use, curing agents, accelerators, reinforcing agents, ene release agents, fillers, etc. are often incorporated into the adhesive. Classified according to use, it can also separate warm glue, sealant, structural glue and so on. There are room temperature curing adhesives and pressure-sensitive adhesives according to the use process. Adhesive can be used to connect dissimilar materials and sheet materials, and the stress distribution at the joint is even. In container manufacturing and repair, epoxy resin, neoprene, and sealant are commonly used. ^[1]

1.According to the application method, it can be divided into thermosetting type, hot melt type, room temperature curing type, and pressure sensitive type.

2. According to the application object, it can be divided into structural, non-structural or special adhesives. The structural adhesives are: epoxy resins, polyurethanes, silicones, polyimides and other thermosetting adhesives;

Synthetic adhesive is composed of main agent and auxiliary agent. The main agent is also called main material, base material or adhesive material.

Thermoplastic

Instantaneous bonding. The instant adhesive does not require heating and pressure when used, and has the characteristics of fast curing and high bonding strength. A 6.45 square centimeter bonding surface can withstand enough tension to lift a car. Such adhesives are used for continuous production streams

Factors affecting adhesiveness and strength

The basic points considered by the above bonding theory are related to the molecular structure of the sticky material and the surface structure of the adherend and the interaction between them. According to the failure test of the bonding system, there are four different situations when the bonding is broken:

1. Interface failure: the adhesive layer is completely separated from the surface of the adhesive body (the adhesive interface is completely detached);

2. Cohesive failure: the failure occurs in the adhesive or the adherend itself, but not between the adhesive interfaces;

3. Mixed damage: The adherend and the adhesive layer are partially damaged or only one of the two is destroyed.

These failures show that the adhesive strength is not only related to the force between the adherent and the adherend, but also to the force between the molecules of the polymer adhesive.

With the improvement of production and living standards, ordinary molecular structure adhesives are far from satisfying people's applications in production and life.

The environmental protection problems of adhesives are mainly environmental pollution and human health hazards, which are due to harmful substances in adhesives, such as volatile organic compounds, toxic curing agents, plasticizers, thinners and other additives, harmful filler Caused by.

Adhesives are widely used in various fields of the national economy because they can achieve the connection of the same or dissimilar materials, no stress concentration at the joints, high bonding strength, and easy implementation of chemical automation operations. Chemical products. The rapid development of the national economy has also provided a broad space for the development of the adhesive industry. China has now become a major producer and consumer of adhesives and tapes.

China's adhesive industry started in the 1950s, and the first production climax in the 1980s. ^{[4] The} rapid development in the past decade has entered a new period of rapid development. ^[5]

The synthetic adhesive industry in the developed countries of the world has now entered a highly developed stage, with an average growth rate of about 3% in the 1990s, while China s average growth rate is 19.5%. After 2008, adhesives have become one of the fastest growing key industries in China's chemical industry.

From 2007 to 2011, the compound growth rates of sales revenue and total profit of the adhesive industry reached 24.52% and 38.56%, respectively. In 2011, China's adhesive industry realized sales revenue of 92.753 billion yuan, an increase of 33.25% year-on-year; total profit reached 6.112 billion yuan, an increase of 59.40% year-on-year. It is estimated that the sales revenue of the adhesive industry in 2012 will exceed 100 billion yuan.

In addition to the continuous and rapid growth of the production and sales scale of China's adhesive industry, the technical level of adhesives has also continued to improve, and a large number of products that have reached advanced levels at home and abroad have been developed, and the products are oriented towards modified, reactive, multifunctional, and nano-oriented The development and application areas are focused on emerging industries such as new energy, energy conservation and environmental protection.

Solvent-free adhesive

Many current adhesives contain a large number of highly volatile solvents, which not only endanger human physical and mental health, but also damage the ozone layer in the atmosphere. It has attracted great attention from the public and the government. This naturally brings a new development trend to the adhesive industry, that is, the development of solvent-free adhesives.

Adhesive Nanomaterials

Nano-adhesives are an important part of the field of materials. The development of nano-adhesives may grab a commanding height in the "nano-economy" battle that is sweeping the world. Nano adhesive will become a dazzling new technology star.

Multifunctional adhesive

When an adhesive has multiple functions at the same time, its application value often increases sharply, so multifunctional adhesives are one of the development trends of the adhesive industry.

Adhesive for military defense

An important feature of the development of the mainland adhesive industry is that sales growth continues to exceed output growth. With the expansion of domestic adhesive production scale, product grade and quality improvement, Chinese adhesive products have gradually entered the international market. Both the export volume and the amount of foreign exchange earned Substantial growth. The application field of adhesives has been continuously expanded, and has been expanded from mainly used in wood processing, construction and packaging industries to clothing, light industry, machinery manufacturing, aerospace, electronics, transportation, medical and health, post and telecommunications, storage and many other fields.

Especially in recent years, the widespread use of China's trademarks, labels and advertisements has accelerated the development of corresponding adhesive varieties, and the amount of glue used in the automotive industry, electronics and electrical appliances, footwear, construction, and food packaging has grown rapidly. The largest consumption of adhesives and sealants in China is in the construction and building materials and decoration industry, followed by the packaging industry, and the fastest growing industries are transportation and assembly.

At present, the market characteristics of China's adhesive industry are: rapid growth in output and sales, new products and equipment are constantly emerging, rapid development of foreign-funded enterprises, environmentally-friendly adhesive production technology and products are highly valued, but the supply of general-purpose low-end products The phenomenon is still serious, the market is fiercely competitive, some important raw materials and high-tech products need to be imported, some important raw materials are in short supply, energy supplies such as coal, electricity, oil are tight, and the price rise is too large, which has increased the burden of production costs of enterprises. ^[6]