Synthetic adhesives are composed of main agent and auxiliary agent. The main agent is also called main material, base material or adhesive; auxiliary agents include curing agent , diluent , plasticizer , filler , coupling agent, initiator, thickener , Anti-aging agents , polymerization inhibitors , stabilizers , complexing agents, emulsifiers, etc., can also include flame retardants, foaming agents, defoamers, colorants and anti-mold agents according to requirements and uses.
Main agent
The main agent is the main component of the adhesive, dominates the bonding performance of the adhesive, and is also an important sign to distinguish the type of adhesive. The main agent is generally composed of one, two, or even three kinds of polymers, and it is required to have good adhesion and wettability. Substances that can be used as sticky materials are:
1. Natural macromolecules, such as starch, cellulose, tannins, gum arabic and sodium alginate and other plant-based adhesives, as well as bone glue, fish glue, blood protein glue, casein and shellac and other animal-based adhesives.
2. Synthetic resins are divided into two categories: thermosetting resins and thermoplastic resins. Thermosetting such as epoxy, phenolic, unsaturated polyester , polyurethane, silicone, polyimide, bismaleimide, allyl resin , furan resin , amino resin , alkyd resin, etc.; thermoplastic resin such as polyethylene , Polypropylene , polyvinyl chloride , polystyrene , acrylic resin , nylon, polycarbonate , polyoxymethylene, thermoplastic polyester , polyphenylene ether, fluororesin, polyphenylene sulfide , polysulfone, polyketone, polyphenylester , Liquid crystal polymer, etc., and its modified resin or polymer alloy . It is the largest type of sticky material.
3. Rubber and elastomer. Rubber mainly includes chloroprene rubber, butyl nitrile ethylene propylene rubber, fluoro rubber, polyisobutylene, polysulfide rubber , natural rubber , chlorosulfonated polyethylene rubber, etc.; elastomers are mainly thermoplastic elastomers and polyurethane elastomers.
4. In addition, there are inorganic binders, such as silicate, phosphate, and phosphoric acid-copper oxide.
Additives
In order to meet specific physical and chemical characteristics, various auxiliary components added are called additives. For example, in order to make the main adhesive material form a network or body structure, and increase the cohesive strength of the adhesive layer, a curing agent (they and the main adhesive material) is added. Reaction and produce cross-linking); in order to accelerate curing and reduce the reaction temperature, curing accelerators or catalysts are added; in order to improve resistance to atmospheric aging, heat aging, arc aging, ozone aging, etc., anti-aging agents are added; in order to give the adhesive some specific properties Fillers are added to reduce the properties and costs; tougheners are added to reduce the rigidity of the adhesive layer and increase toughness; diluents are added to improve the processability and reduce the viscosity and extend the service life. include:
1. Curing agent
2. Solvent
3. Plasticizer
4. Filler
5. Toughener
6. Coupling agent
7. Other additives: initiators, accelerators, tackifiers, polymerization inhibitors, stabilizers, antioxidants, complexing agents, emulsifiers.
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