The use of adhesives is used in all aspects of life and production, such as adhesives for led aluminum substrates, adhesives for automotive interior parts, adhesives for packaging materials, surface bonding of shoe materials and other construction or decorative materials, etc. So what are adhesives? What are the types and uses of adhesives?
What is an adhesive?
Adhesive bonding (bonding, bonding, gluing, gluing) refers to the technology in which the surfaces of homogenous or dissimilar objects are joined together with adhesives, which have the characteristics of continuous stress distribution, light weight, or sealing, and most process temperatures are low. Adhesive bonding is especially suitable for the connection of different materials, different thicknesses, ultra-thin specifications and complex components.
A class of natural or synthetic, organic or inorganic substances that can connect two or more parts or materials together through interfacial adhesion and cohesion, collectively referred to as adhesives (Adhesive), also known as adhesives. Called adhesive, adhesive, customarily referred to as glue or glue. In short, an adhesive is a substance that binds the adherends together through adhesion. "Adhesive" is a generic standard term.
Introduction to the types and uses of adhesives
There are many types of adhesives, which can be divided into many types according to their components, uses, and physical forms. Here, the classification and uses of adhesives are sorted out from these three aspects.
There are many types of adhesives, the more common ones are: urea-formaldehyde resin adhesives, polyvinyl acetate adhesives, polyacrylic resin adhesives, polyacrylic resins, polyurethane adhesives, hot melt adhesives, epoxy resin adhesives, synthetic adhesives and so on.
1. Silicone adhesive
It is a kind of sealing adhesive, which has the characteristics of cold resistance, heat resistance, aging resistance, water resistance, moisture resistance, high expansion fatigue strength, small deformation and non-toxicity. In recent years, such adhesives have developed rapidly in China, but at present, the raw materials of organic silicone adhesives in my country are partly imported.
2. Polyurethane adhesive
A variety of materials can be bonded, and the physical and chemical properties of the material can be maintained at low or ultra-low temperature after bonding. It is mainly used in shoemaking, packaging, automobiles, magnetic recording materials and other fields.
3. Polyacrylic resin
Mainly used in the production of pressure-sensitive adhesives, but also in the textile and construction fields.
Construction adhesives: mainly used for construction decoration, sealing or bonding between structures.
4. Hot melt adhesive
According to different raw materials, it can be divided into EVA hot melt adhesive, polyamide hot melt adhesive, polyester hot melt adhesive, polyolefin hot melt adhesive, etc. At present, the main domestic production and use is EVA hot melt adhesive. The main raw materials of polyolefin series adhesives are ethylene series, SBS, SIS copolymer.
5, epoxy resin adhesive
It can bond between metals and most non-metallic materials, and is widely used in construction, automobiles, electronics, electrical appliances and daily household items
6. Urea-formaldehyde resin, phenolic, melamine-formaldehyde adhesive
Mainly used in the wood processing industry, the formaldehyde emission after use is higher than the international standard.
Adhesives for wood processing: for medium density fiberboard, gypsum board, plywood and particleboard, etc.
7. Synthetic adhesive
Mainly used in wood processing, construction, decoration, automobile, shoemaking, packaging, textile, electronics, printing and binding and other fields. At present, my country imports nearly 200,000 tons of synthetic adhesives every year, including hot melt adhesives, silicone sealant adhesives, polyacrylic acid adhesives, polyurethane adhesives, and PVC plastic adhesives for automobiles. At the same time, about 20,000 tons of synthetic adhesives are exported every year, mainly polyvinyl acetate, polyvinyl acid formal and pressure-sensitive adhesives.
Classification by use
1. Sealing adhesive
Mainly used for the connection of doors, windows and prefabricated houses. The sealing adhesives are silicone and polyurethane adhesives, and the mid-range ones are neoprene adhesives, polyacrylic acid, etc. In my country, in the construction adhesive market, silicone adhesives and polyurethane sealing adhesives should be the direction of future development. At present, they account for about 30% of the sales volume of construction sealing adhesives.
2. Adhesives for building structures
Mainly used for the connection between structural units. Such as external repair of reinforced concrete structures, metal reinforcement and fixation, and construction on site, epoxy resin series adhesives are generally considered.
3. Adhesives for automobiles
It is divided into 4 types, namely, adhesives for car body, interior decoration, windshield and car body chassis.
At present, the annual consumption of automotive adhesives in my country is about 40,000 tons, of which PVC plastic adhesives, neoprene adhesives and asphalt series adhesives are used.
4. Adhesives for packaging
It is mainly used to make pressure-sensitive tapes and pressure-sensitive labels, and to bond the surface of packaging materials such as paper, plastic, and metal. The adhesive for paper packaging materials is polyvinyl acetate emulsion. Adhesives for plastic and metal packaging materials are polyacrylic emulsions, VAE emulsions, polyurethane adhesives and cyanoacrylate adhesives.
5. Electronic adhesives
The consumption is relatively small, currently less than 10,000 tons per year, most of which are used in integrated circuits and electronic products, and now mainly use epoxy resin, unsaturated polyester resin, and silicone adhesive. We can supply end-capping adhesives for electronic components with a thickness of 5 microns, but the adhesives for electronic components with a thickness of 3 microns need to be imported from abroad.
6. Adhesive for shoe making
The annual consumption is about 125,000 tons, of which 110,000 tons are needed for neoprene adhesives and about 15,000 tons for polyurethane adhesives. Since neoprene adhesives require benzene as a solvent, and benzene is harmful to the human body, the development should be restricted. In order to meet the development needs of the footwear industry, the use of polyurethane series adhesives will be the direction.
Classification by physical form
Classification by sealant vulcanization method
(1) Moist air vulcanized sealant
This family of sealants is vulcanized with moisture in the air. It mainly includes one-component polyurethane, silicone rubber and polysulfide rubber. The polymer base material contains active groups, which can react with water in the air to form cross-linking bonds, so that the sealant is vulcanized into a network structure.
(2) Chemical vulcanization sealant
Two-component polyurethane, silicone, polysulfide, neoprene, and epoxy sealants fall into this category and are generally cured at room temperature. Certain one-component chlorosulfonated polyethylene and neoprene sealants and polyvinyl chloride sol paste sealants must be cured by chemical reaction under heating conditions.
(3) Thermal transformation type sealant
The combination of plasticizer-dispersed polyvinyl chloride resin and bituminous rubber is two different types of thermal transition systems. Vinyl plasticizers are liquid suspensions at room temperature and harden by heating to solidify; rubber-asphalt sealants are hot-melt.
(4) Oxidation hardening sealant
Surface-drying sealants for inlay or installation glass are mainly based on dry or semi-dry vegetable or animal oils, which can be refined polymerized, blown or chemically modified.
(5) Solvent volatilization solidifying sealant
This is a sealant based on non-viscous polymer after solvent evaporation. This type of sealant mainly includes butyl rubber, high molecular weight polyisobutylene, acrylate with a certain degree of polymerization, chlorosulfonated polyethylene and neoprene rubber sealants.