Adhesives belong to the category of organic high-molecular compounds. With the advancement of technology, various multifunctional, high-performance adhesives have found increasingly widespread applications in modern industrial fields, becoming indispensable materials in modern and national defense industries. Adhesives are classified in many ways. From the perspective of current development and concepts, the adhesive industry is moving toward energy conservation, environmental protection, low cost, and high performance. Therefore, the development of low-toxicity and non-toxic environmentally friendly adhesives has become the mainstream trend in the adhesive industry. In the future, the development of adhesives should focus on environmentally friendly hot-melt, water-based, and solvent-free adhesives. The future synthetic adhesive market will be dominated by low-pollution water-based and hot-melt adhesives.

From an environmental perspective, environmentally friendly adhesives are categorized as follows:

1. Solvent-free adhesives: These adhesives do not release solvents, preventing environmental pollution. Currently, hot-melt adhesives are the primary example. These adhesives are solvent-free solid adhesives using thermoplastic polymers (resins, rubbers) as their base material. They are characterized by rapid bonding, wide applicability, non-toxicity, and non-pollution, making them suitable for continuous production and easy storage and transportation.

2. Water-based adhesives: These adhesives use water as a dispersion medium and are further divided into water-soluble, water-dispersible, and water-emulsion adhesives. Advantages of water-based adhesives include being environmentally friendly, non-toxic, non-flammable, having high solid content, and being compatible with existing application equipment, which is easy to clean.

3. Inorganic adhesives: These comprise a wide range of adhesives composed of inorganic salts, inorganic acids, inorganic bases, and metal oxides. Inorganic adhesives are a novel type of adhesive with numerous varieties. Based on curing conditions, they are classified as air-drying, water-curing, hot-melt, and reaction types. Most inorganic adhesives are pastes formed by mixing solids and liquids, with readily available raw materials.

The Development Path of Environmentally Friendly Adhesives:

Environmental protection is a global issue and a focal point of concern across various industries. Taking the packaging industry as an example, China's flexible packaging industry has experienced rapid growth in recent years, leading to increasingly prominent concerns regarding health and environmental impacts. Among these, adhesives used in flexible packaging have consistently been a central topic of discussion. Therefore, the application prospects of environmentally friendly adhesives in this industry are extremely broad.