The basic composition of the adhesive

Basic composition of adhesives: including adhesives, curing agents, accelerators, toughening agents, plasticizers, thickener diluents, antioxidants, polymerization inhibitors, coupling agents, initiator photosensitizers, defoamers, antisepsis Agents, fillers, solvents, etc. Not every type of adhesive has these components. In addition to sticking material must be other

Adhesive, also known as base material or rubber compound, is the basic component that determines adhesive properties. Adhesives that can be used as adhesives are natural polymer compounds (starch, glue, shellac, gelatin, casein, rosin, natural rubber Etc.), modified natural polymer compounds (nitrocellulose, sodium carboxymethyl cellulose), synthetic polymer compounds (synthetic resins, synthetic rubbers, thermoplastic elastomers, etc.), organic compounds, inorganic compounds (silicates, phosphoric acid, etc.) Salt, sulfate, borate, zinc oxide, magnesium oxide, etc.).

(1) Curing Agent Curing Agents, also known as hardeners, curing agents, or modifiers, refer to a class of substances that can convert soluble, meltable linear structure macromolecule compounds into insoluble, infusible body structures. It participates in a chemical reaction itself and becomes a part of a cured product. For some types of adhesives, such as epoxy resins, phenolic resins, urea-formaldehyde resins, melamine formaldehyde, furan resins, etc., curing agents are indispensable. The curing agent has an important influence on the performance of the adhesive. The ideal curing agent should be selected according to the type of adhesive in the adhesive, the performance requirements of the adhesive, the specific process method, environmental protection issues, health hazards, and price.

(2) Cross-linking is a process in which cross-linking agents can form chemical bonds between macromolecules in linear or branched polymer chains. Cross-linking substances that make the backbone of polymer macromolecules are called cross-linking agents. The cross-linking agent is often a substance containing a plurality of reactive functional groups, such as a dibasic acid, a diamine, a polyhydric alcohol, a polyisocyanate, or a compound containing an unsaturated double bond, and sulfur, an organic peroxide, an organometallic compound, Metal oxides and so on. The cross-linking agent plays an important role in the modification of the adhesive and can improve the adhesive strength, heat resistance, chemical resistance, creep resistance, aging resistance, and the like.

(3) Accelerators Any substance that accelerates the reaction rate of adhesives and sealant curing agents, collectively referred to as accelerators. Adding a small amount of accelerator can greatly accelerate the curing reaction, reduce the curing temperature, shorten the curing time, reduce the amount of curing agent, and can also improve the physical and mechanical properties. For example, DMP-30 can cure epoxy-polysulfide-low molecular polyamide adhesives below 150C; 2-ethyl-4 methylimidazole can reduce the temperature of dicyandiamide-cured epoxy resins.

(4) Toughening agents can reduce brittleness, improve toughness, and do not affect the other main properties of the adhesive material called toughener. Toughening agents generally contain active groups that can interact with the resin, are not completely compatible after curing, and sometimes also phase separation, will obtain a better toughening effect, it will be very little heat distortion temperature, and impact resistance It has also significantly improved. For example, the carboxyl-terminated liquid nitrile rubber (CTBN) is an epoxy resin's excellent toughening agent. The epoxy-CTBN system 1200C has a peel strength of 4.4 to 13.2 kN.m-1 after curing and a shear strength of 27 to 41 MPa.

(5) Plasticizers Plasticizers are high-boiling volatile liquids or low-melting solids that increase the fluidity of the adhesive and make the film flexible. Plasticizers generally do not chemically react with the main components of the adhesive. By weakening the physical interactions between polymer molecules, they can also reduce brittleness and increase toughness. However, the rigidity, strength, and heat distortion temperature of the adhesive film are greatly reduced. Plasticizer and adhesive components must have good compatibility to ensure that the adhesive performance is stable and durable.

(6) Tackifiers Tackifiers are resins, rubbers, organic compounds, etc. added to increase the adhesive's initial tackiness, pressure-sensitive tackiness, and tackiness. Commonly used tackifiers include terpene resins, terpene-phenolic resins, rosin, hydrogenated rosin, polyisobutylene, lanolin, and sucrose.

(7) Thickeners Substances that increase the viscosity of adhesives and sealants are called thickeners, and they certainly regulate viscosity, stability, anti-settling, infiltration, flow prevention, and thixotropic effects. Commonly used thickeners include starch, polyacrylamide, sodium polyacrylate, guar gum powder, polyethylene oxide, natural rubber, styrene-butadiene rubber, agar, fumed silica, organic bentonite, and the like.

(8) Diluent is used to reduce the viscosity of the adhesive material, can improve the fluidity, wettability, permeability, easy to mix evenly, increase the amount of filler, facilitate the coating operation and extend the pot life. Diluents are broadly categorized into two categories, viable or non-volatile, non-reactive diluents that can participate in the curing reaction inactive diluent and only physically mix.

(9) Antioxidants Aging agents are added to prevent the aging of the polymer compound in order to extend the service life of the adhesive. It includes antioxidants, light stabilizers, heat stabilizers, variable metal inhibitors, etc. The substances that delay or inhibit oxidative degradation are called antioxidants, and are also customarily called antioxidants. Antioxidants commonly used are antioxidant 264, antioxidant 4010, antioxidant RD, antioxidant KY-405, antioxidant D-50, propyl gallate, UV absorber UV-531 and so on.

(10) Polymerization inhibitors, also known as inhibitors, are extensions of the pot life of adhesives containing unsaturated double bonds (such as cyanoacrylates, anaerobic adhesives, modified acrylic fast-curing adhesives, unsaturated polyester adhesives, etc.) And storage period of the material, such as hydroquinone, p-tert-butyl catechol, p-benzoquinone and so on.

(11) A coupling agent is a functional compound that contains groups of different nature at both ends of the molecule, one end of which reacts with the surface of the inorganic substance and the other end reacts with the organic molecule, in the form of a chemical bond, between two different substances. Plays a role as a bridge. This improves the surface properties of the adhesive, increases interfacial adhesion, and improves water resistance, heat resistance, and durability. The coupling agent is classified into an organic silane coupling agent, a titanate coupling agent, a zirconate coupling agent, a zircoaluminate coupling agent, an organic complex, and the like. Organic silane coupling agents are commonly used in adhesives.

(12) Flame retardants are auxiliaries that prevent flammable substances from igniting or inhibiting flame propagation, including organic or inorganic substances containing phosphorus, halogen, boron, bismuth, aluminum, etc. that improve the flame retardancy of flammable adhesives. . Flame retardants are divided into reaction type and additive type. Commonly used flame retardants include phosphates, halogenated hydrocarbons, antimony oxides, and aluminum hydroxides.

(13) Initiators Initiators are substances that cause the activation of monomer molecules or prepolymers during polymerization to generate free radicals. Preparation of solvent-based and reported liquid acrylic pressure-sensitive adhesives, vinyl acetate solvent-based construction adhesives, polyvinyl acetate emulsions, VAE emulsions, acrylic emulsions, neoprene latex, styrene-butadiene latex, grafted neoprene adhesives, SBS grafting Adhesives, as well as cross-linked curing of unsaturated polyester resins, anaerobic adhesives, and curing of second-generation acrylate adhesives, must all use initiators. Common initiators include benzoyl peroxide (BPO) and cumene. Hydrogen peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, azobisisobutyronitrile, ammonium persulfate, potassium persulfate, and the like.

(14) Filler, also known as filler, is one of the important compounding agents for adhesives. It has reinforcing, thickening, compatibilizing, coloring, flame retardant, anti-wear, anti-corrosion, increasing hardness, reducing shrinkage, reducing coefficient of thermal expansion, Exothermic temperature, increased thermal conductivity, conductivity, magnetic conductivity, thixotropy, improved water resistance, heat resistance, aging resistance, extended pot life and other functions, fillers to improve the performance of the adhesive, change the performance of the construction and reduce Product costs have a very obvious effect. A wide variety of fillers, according to chemical composition is divided into inorganic fillers and organic fillers; according to its appearance, there are powder, granular, flake, fiber, fabric, hollow microspheres and other points. The emerging ultra-fine powder, nano-scale, and whisker-like fillers are extremely effective in improving the performance of adhesives.

(15) Defoamers are a class of substances that prevent the formation of foams or foams. They are also known as antifoams and antifoams. Foam can cause great difficulties in the production and coating of adhesives, and can cause air holes in the adhesive layer, affecting the adhesive properties. Therefore, it is necessary to try to destroy or prevent the generation of bubbles. The most effective method is to use defoamers. A good defoamer can both defoam and inhibit foaming.

(16) Preservatives Agents that kill, inhibit or prevent the growth of microorganisms or fungi. As well as chemicals that prevent corrosion of metals, they are collectively referred to as preservatives, including anti-mold agents, rust inhibitors, and corrosion inhibitors. In water-based adhesives made of starch, bone glue, fiber derivatives, natural rubber latex, polyvinyl alcohol, etc., bacteria and molds proliferate easily, and during storage, the glue becomes black, odor, swelling, spoilage, and cannot be used. It must be added. Appropriate mildew, sterilization. If the adhesive contains strong acidic or alkaline components, it will corrode metal during storage and use, and rust inhibitors or corrosion inhibitors should be added to prevent corrosion.

(17) Photosensitizers Photosensitizers, also known as photoinitiators or sensitizers, are compounds that absorb certain wavelengths of ultraviolet light to produce radical ions. The photosensitizer is an important component of the radiation curing system such as an optical photosensitive adhesive, a photoresist, a photo-curing anaerobic adhesive, and the like, and an extremely fast-curing pollution-free green adhesive can be obtained.

(18) Solvents are liquids that can reduce the intermolecular force of certain solid or liquid molecules and disperse the dissolved substances into a homogeneous system of molecules or ions. Solvent is an indispensable component of solvent adhesives, because most organic solvents have certain toxicity, flammability, explosiveness, causing toxic to the human body, polluting the environment, and causing potential safety problems, thus making solvent-based adhesives Subject to environmental regulations, but because of the special properties of some aspects of solvent-based adhesives, it cannot be completely replaced by water-based adhesives in the short term. Therefore, non-toxic or low-toxic solvents must be used to make adhesives that are harmless to the human body, the environment, and safety.