The latest classification of water based adhesives
Since the 1980s, adhesive and bonding technology has made remarkable progress, new and excellent adhesives have emerged, and because of its unique adhesive technology, it has extraordinary versatility and can achieve multiple purposes, so it has been more widely used. application.
There are many classification methods for adhesives, which are not uniform. Commonly used are:
1. Classification by chemical composition
This is a more scientific classification that separates adhesives into organic and inorganic water based adhesives.
(1) Organic adhesive
Synthetic adhesives are resin type, rubber type, composite type, etc.;
Natural adhesives include adhesives such as animals, plants, minerals, and natural rubber;
(2) inorganic adhesive
According to the chemical composition, there are various kinds of phosphates, silicates, sulfates, borates and the like.
2, according to the different forms of curing
There are three major categories of solvent volatilization, chemical reaction and hot melt.
(1) Solvent volatile type
It is a total solvent evaporation type adhesive in which a solvent evaporates from an adhesive surface or a solvent absorbs a solvent by itself to form an adhesive film and exhibits adhesive force. Its curing speed is related to the temperature and humidity of the environment, the degree of looseness of the adherend, the water content, and the pressing method, that is, the speed of evaporation of the solvent. Commonly used varieties are: phenolic resin, polyvinyl acetate, polyacrylate, styrene butadiene rubber, neoprene adhesive.
(2) Chemical reaction type
The adhesive is cured by irreversible chemical changes to produce a bonding force. The preparation method includes one-component, two-component or even three-component, and is mixed as required when used.
The room temperature curing type, the heat curing type, and the like are classified according to curing conditions.
(3) Heat curing type
The heat-curing type adhesive needs to heat the adherend coated with the adhesive to promote the chemical change. Commonly used varieties are: epoxy resin, phenolic resin, unsaturated polyester, polysulfide rubber, epoxy-phenolic resin adhesive.
(4) Hot melt type
The hot melt adhesive bonds the solid polymer by heating and melting, and then solidifies by cooling to exert adhesive force. Commonly used varieties are: leather glue, bone glue, asphaltene, rosin, paraffin, polystyrene, butyl rubber and so on.
3. Classified by purpose
This can be divided into structural adhesives, non-structural adhesives and special adhesives (such as high temperature resistance, ultra-low temperature, electrical conductivity, thermal conductivity, magnetic permeability, sealing, water bonding, etc.). Among them, the structural adhesive requires that the rubber joint of the stressed component is subjected to stress and the adherend is equivalent or close.
4, classified by application method
There are room temperature curing type, thermosetting type, hot melt type, pressure sensitive type, rewet type and other cements.
In order to meet the needs of cementing technology in industrial and agricultural production and social life, countries have made great efforts in developing adhesive varieties, and they have developed rapidly. Some fast curing, one-component, high-strength, high-temperature, solvent-free have appeared. Low viscosity, non-polluting, energy-saving, multi-functional and other adhesives.
In the field of synthetic adhesives, the use of molecular design to develop high-performance adhesives; the use of technology, copolymerization, blending, interpenetrating network polymer (IPM) and other technologies to improve the performance of adhesives. New progress has been made in the study of the adhesive mechanism; new developments have been made in the sizing equipment and tools. For example, the combination of adhesive and mechanical connection, adhesive and brush plating technology has formed a new composite repair technology.
5, according to the appearance of the adhesive classification
There are solution type, latex type, paste type, powder type, film type and solid type.
Most of the adhesives are of the solution type, that is, the resin or rubber is dissolved in a suitable organic solvent or water to form a viscous liquid. The curing is caused by evaporation of a solvent or water (solvent evaporation type) and chemical reaction (chemical reaction type, which does not contain a solvent). Commonly used varieties are: phenolic resin, epoxy resin, polyvinyl acetate, styrene butadiene rubber.
An emulsion or latex type adhesive is a water-dispersible type of adhesive in which a resin or a rubber is dispersed in water. It is usually milky. Commonly used varieties are: polyvinyl acetate, polyacrylate, neoprene, silicone rubber and so on.
Paste-type adhesives are highly non-existent and highly viscous. Adhesive, mainly used for sealing. Putty, caulking, and sealing materials all fall into this category. Commonly used are: unsaturated polyester, polyurethane, vinyl acetate, reclaimed rubber, silicone rubber and so on.
The powder adhesive is water-soluble and is added to a paste or liquid before use, and then used. Commonly used varieties are: starch, shellac, polyvinyl acetate and so on.
The film adhesive is made of cloth, paper, glass fiber or the like as a substrate, coated or adsorbed with an adhesive, and then dried into a film, or directly formed into a film material with an adhesive and a base.
Membrane adhesives have high heat resistance and adhesive strength. Commonly used varieties are: epoxy-polyamine, nylon-epoxy, phenolic-polyvinyl acetal. Solid adhesives are primarily hot melt adhesives.
Polyurethane is a material for producing a main component in a polyurethane adhesive. When the adhesive is a one-component adhesive, the composition is basically a polyurethane resin. In this case, it can be said that the two are the same, but often the adhesive It is a two-component or multi-component, and you cannot simply equate the two products.