Methylcyclohexylenediamine (HTDA) is a kind of alicyclic amine monomer with side methyl group, it is a new type of alicyclic amine epoxy resin curing agent, Cas No:13897-55-7. It can be used as curing agent alone, or mixed with other common epoxy curing agents (e.g. aliphatic amine, alicyclic amine, aromatic amine, acid anhydride, etc.) or general-purpose accelerators (e.g. tertiary amine, imidazole), to cure epoxy resins in a wide range of temperatures, applicable to composites, coatings, adhesives, flooring and other fields, can be used in the organic synthesis of polyamides, polyimides and other polyurethanes; it can be used in polyurethane to do the amine chain expander, and to form urea with the isocyanate group, which is the main component of the urea chain. It can be used in polyurethane as amine chain extender to form urea bond with isocyanate group and improve the comprehensive performance of the product.   Product characteristics Unique application period without loss of mechanical strength Very low viscosity, easy to mix with other curing agents Low active hydrogen equivalent, small additive ratio Very low vapour pressure Moderate curing speed for improved handling in composites, adhesives and flooring applications   References                       Appearance (25°C): colourless or yellowish transparent liquid Colour: ≤1 Viscosity(mPa.s/25°C): 5-15 Amine value (mgKOH/g): 850-900 Active hydrogen equivalent (g/ep): 32 Purity(%): ≥99.5 Water content(%):≤0.2 Boiling point(℃):213 Specific gravity(g/mm³):0.94 Additive amount: 16-17   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents.   We will be at your service 24 hours a day. Pls contact us freely.    

Electronic encapsulation adhesive is used to encapsulate electronic devices, is to play a sealing, encapsulation or potting of a class of electronic glue or adhesive. After the electronic encapsulation adhesive package can play the role of waterproof, moistureproof, shockproof, dustproof, anti-corrosion, heat dissipation, confidentiality. Therefore, electronic packaging adhesive needs to have high and low temperature resistance, high dielectric strength, good insulation, environmental protection and safety features.   Why choose epoxy resin? With the continuous development of large-scale integrated circuits and the miniaturisation of electronic components, the heat dissipation of electronic components has become a key issue affecting their service life, and there is an urgent need for high thermal conductivity adhesives with good heat dissipation properties as encapsulation materials. Epoxy resin has excellent heat resistance, electrical insulation, adhesion, dielectric properties, mechanical properties and small shrinkage, chemical resistance, add curing agent and have better processing and operability. Several kinds of special epoxy resin introduction   Biphenyl epoxy resin Tetramethylbiphenyl epoxy resin synthesised by two-step method is cured by DDM and DDS, showing high heat resistance, good mechanical properties and low water absorption.   Silicone-containing epoxy resin Another research hotspot in the field of electronic encapsulation is the introduction of organosilicon chain segments, which can not only improve heat resistance, but also enhance the toughness of the epoxy after curing, and silicone-containing polymers have good flame retardant properties, the low surface energy of silicone-containing groups cause them to migrate to the surface of the resin to form a heat-resistant protective layer, thus avoiding further thermal degradation of the polymer.   Fluorine-containing epoxy resin Fluorine-containing polymers have many unique properties, the fluorine element has the largest electronegativity, the force between the electron and the nucleus is large, the bonding energy of the chemical bond with other atoms is large, the refractive index is low, and the fluorine-containing polymers are excellent in heat resistance, oxidation resistance, and resistance to pharmaceutical properties.  Fluorine-containing epoxy resin with dust self-cleaning, heat, wear, corrosion and other properties and also improve the solubility of epoxy resin, at the same time, has excellent flame retardant, become a new material in the field of electronic packaging.   Dicyclopentadiene-containing epoxy resin Dicyclopentadiene-o-cresol resin can be synthesized by Friedel-Crafts reaction. The resin is cured with methyl hexahydrophthalic anhydride and polyamide 651 curing agent, and the Tg of the cured material is 141°C and 168°C, respectively, which is about 20°C higher than that of the simple E51 cured resin.   Naphthalene-containing epoxy resin A new naphthalene-containing structural phenolic epoxy resin has been synthesised. Its DDS cured product shows excellent heat resistance, Tg is 262°C, 5% heat loss is 376°C.   Alicyclic epoxy resin Alicyclic epoxy resins are characterised by high purity, low viscosity, good workability, high heat resistance, low shrinkage, stable electrical properties and good weathering, etc. They are particularly suitable for high-performance electronic encapsulation materials with low viscosity, high heat resistance, low water absorption and excellent electrical properties, and are highly promising electronic encapsulation materials.   Hybrid modified epoxy resin Blending is an important method to effectively improve material properties. In a kind of epoxy matrix, mixed with another kind of epoxy resin or several kinds of epoxy resin, so that the matrix material of a particular kind of performance or several kinds of specific performance improvement, so as to obtain the comprehensive performance of the new material is more excellent. In epoxy moulding plastics, through the blending can achieve the goal of cost reduction, improve the use of performance and processing performance.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents.     We will be at your service 24 hours a day. Pls contact us freely.

Polyetheramines are part of the Yolatech product family. They generally contain a primary amine group attached to one end of the polyether backbone. The polyether backbone is typically composed of propylene oxide (PO), ethylene oxide (EO) or a PO/EO blend. This is why they are called "polyether amines". Epoxy resins react with polyether amines in a typical amine reaction, and polyether amines give excellent elasticity, toughness and low colouration to the cured product. Polyetheramine's low viscosity and proper workability time facilitates the production of epoxy resin adhesives.   Polyetheramine T-5000 polyetheramine is a trifunctional primary amine with an average molecular weight of about 5000. It is a clarified, nearly colourless, viscous liquid.   Polyetheramine T-5000 Typical Physical and Chemical Data Appearance: colourless to light yellow Colour phase (Pt-Co): 75 Max. Active hydrogen equivalent (g/eq): ~952 Viscosity (25°C, cst): 819   Pros Light colour Increases peel strength in epoxy adhesives Increases toughness   Applications Crosslinking agent for polyurea Auxiliary curing agent for epoxy systems where adhesion and flexibility are required Surfactants and corrosion inhibitors   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents.   We will be at your service 24 hours a day. Pls contact us freely.  

Epoxy resin adhesive is a widely used chemical grouting materials, epoxy resin adhesive with high strength, good adhesive force, low curing shrinkage, in line with a variety of process needs, can meet the needs of concrete crack repair. Epoxy resin and polyamide as the main film-forming substances, compound diluent, accelerator, etc. made of glue, according to the gap, supplemented by atmospheric pressure or high pressure grouting method will be injected into the cracks, so as to achieve adhesion, reinforcing, seepage and other repair effects. Here we introduce two commonly used epoxy resin products, used in concrete reinforcement, with good adhesive strength, levelling performance and excellent mechanical properties.   YL-128 Epoxy equivalent (g/eq): 184 ~ 190 Viscosity (cps/25℃): 12000 ~ 15000 Product Description: Standard bisphenol A epoxy resin for general use.   YL-127 Epoxy equivalent (g/eq): 176 ~ 184 Viscosity (cps/25℃): 8000 ~ 11000 Product Description: Low viscosity standard bisphenol A epoxy resin.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents. We will be at your service 24 hours a day. Pls contact us freely.

1,3-cyclohexanedimethylamine CAS No.579-20-6,short for 1,3-BAC,is used as a raw material for epoxy resin curing agents in a wide range of applications around the world. 1,3-BAC, as an alicyclic amine, has excellent hardness, weathering, and chemical resistance, a refined appearance, and a faster cure rate.   Typical Physical and Chemical Data Appearance: Colourless transparent liquid Colour (G):1.0 Max Viscosity (mPa.s/20℃): 9.1 Active hydrogen equivalent(g/eq): 35.6   Advantages of 1,3-BAC as an epoxy resin curing agent Excellent UV resistance and transparency Fast curing speed Excellent curing at high temperatures & high humidity Low active hydrogen equivalents, low additions Low solidification point Good curing even at low temperatures.   Application of 1,3-BAC      In jewellery adhesive 1,3-BAC's excellent resistance to yellowing provides a long-lasting guarantee for the glossy appearance of the jewellery adhesive. 1,3-BAC provides hardness guarantee for jewellery. 1,3-BAC lower addition faster curing speed to improve the overall cost-effective advantage.      In seam sealer Improve the curing speed, 1,3-BAC can fully guarantee the curing time. 1,3-BAC low colour, high transparency to fully guarantee the appearance of the product colour. 1,3-BAC provides the required hardness and strength to the product.     In composite materials 1,3-BAC low active hydrogen equivalent, low additive quantity can bring higher cost-effective advantage for products. 1,3-BAC high hardness, to provide assurance for the strength of the product. 1,3-BAC good chemical resistance, to ensure that the product's lasting use.     In laminating adhesive 1,3-BAC's excellent resistance to yellowing provides assurance of long-lasting colour stability of the cured product. 1,3-BAC's excellent colour transparency ensures the transparent and clear quality of the product. The low viscosity of 1,3-BAC ensures good workability.   1,3-BAC (1,3-cyclohexanedimethylamine) is now widely used as epoxy resin curing agent in coatings, adhesives, composites, etc. 1,3-BAC is one of the amines with less additive quantity at present, and its excellent product appearance and performance make it have an outstanding cost-effective advantage.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of epoxy resin curing agents or hardeners and diluents.   We will be at your service 24 hours a day. Pls contact us freely.  

Epoxy terrazzo flooring is produced using epoxy resin and curing agents as binders, supplemented with various decorative aggregates, and manufactured through special processes. Epoxy terrazzo flooring can be widely applied in large-scale shopping malls, high-end commercial buildings, luxury clubs, exhibition halls, hotel lobbies, as well as residential and villa floor decorations. Epoxy terrazzo flooring features moisture resistance, slip resistance, waterproofing, dust prevention, and durability. Polyetheramine products used as curing agents in epoxy terrazzo flooring Polyetheramine D-230 Polyetheramine D-230 is a bifunctional amine with an average molecular weight of about 230. Features: Low viscosity, low color, low volatility Fully miscible with various solvents, including water The cured product is tough, clear, and has excellent impact resistance, suitable for coatings, casting, adhesives, etc. The coating surface does not exhibit common whitening phenomena associated with the use of other amine curing agents Typical Data: Appearance: Colorless and transparent Average active hydrogen equivalent (g/eq): ~60 Color (Pt-Co): ~25 Viscosity (cst, 25℃): ~9.5                                                                                                                                                          Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents. We will be at your service 24 hours a day. Pls contact us freely.    

  Dicyandiamide curing agent belongs to the heating curing class of latent curing agent, solid at room temperature, insoluble in epoxy resin, dispersed in epoxy resin in the form of microparticles, through the heating reaction, once heated to the melting point of the vicinity of the start of the dissolution and rapid reaction curing.   Curing reaction of dicyandiamide The molecular structure of dicyandiamide contains a cyano group (-CN) in addition to four active hydrogens. Cyano group can also participate in the curing reaction as a functional group. The curing reaction temperature of dicyandiamide is generally in the range of 160~180°C, and the curing reaction time is 20~60 minutes. For bisphenol A epoxy resin with 190 epoxy equivalents, the theoretical dosage of dicyandiamide curing agent (calculated on the basis of active hydrogen equivalents) is 11.1 parts, but the actual dosage is often in the range of 4-10 parts (based on 100 parts of the resin by mass). Dicyandiamide micropowder is dispersed into the epoxy resin, has a suitable storage period, is stable in storage, does not delaminate, and does not cure.   The fineness of the dicyandiamide particles may vary from product to product. The finer the dicyandiamide particles, the more obvious the performance advantage for curing reaction Ultra-fine dicyandiamide particles are easier to be evenly dispersed into the epoxy resin liquid. Ultra-fine dicyandiamide particles can be better mixed and dissolved in the epoxy resin liquid than ordinary dicyandiamide.   Application areas of dicyandiamide curing compounds Dicyandiamide epoxy resin has good adhesive property, heat resistance and stable storage period. Dicyandiamide epoxy resins can be widely used in powder coatings, carbon fibre prepregs, heat curable inks, laminates, single component adhesives and other applications. Typical applications: Preparation of prepregs for the manufacture of reinforced composites (wind energy, automotive, aerospace, marine engineering and other industries). Electronic packaging materials, adhesives. Powder coatings (especially heavy duty anti-corrosion function). For epoxy-based adhesives (reinforced materials).   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents.   We will be at your service 24 hours a day. Pls contact us freely.    

Epoxy resin adhesive is a reprocessing or modification of epoxy resin to make its performance parameters meet specific requirements. Usually epoxy resin adhesives are also used with curing agents and need to be mixed well to be fully cured. Generally, the epoxy resin adhesive is called A adhesive or main agent, and the curing agent is called B adhesive or curing agent(hardener).   Main properties of epoxy resin adhesives before curing Colur, viscosity, specific gravity, proportioning, gel time, open time, curing time, thixotropy (flow stopping), hardness, surface tension, etc.   Main properties of epoxy resin adhesive after curing Resistivity, proof voltage, water absorption, compressive strength, tensile strength, shear strength, peel strength, impact strength, heat deflection temperature under load, glass transition temperature, internal stress, chemical resistance, elongation, shrinkage coefficient, thermal conductivity, electrical conductivity, weathering resistance, aging resistance, dielectric constant.   Curing characteristics of epoxy resin adhesive Most of the epoxy resin adhesives are heat-setting adhesives. The higher the temperature of the epoxy resin adhesive, the faster the curing. The more the amount mixed at one time, the faster the curing. The curing process has exothermic phenomenon, etc.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents. We will be at your service 24 hours a day. Pls contact us freely.  

Background Under normal conditions, bisphenol A-type liquid epoxy resins are colorless, transparent and flowable. When the external temperature is lowered, the molecular chain is less active and prone to crystal seeding. Liquid epoxy resin appears grey in color, free-floating crystals, crystal clusters, or hard lumps like curing, we call it the crystallization phenomenon.   Reasons for the crystallization of epoxy resin The reasons for the crystallization of epoxy resin are complex, we mainly summarize the following. High purity. We all know that crystals are highly pure substances, and so is epoxy resin, the higher the purity, the narrower the molecular distribution, the easier it is to crystallize. Low viscosity. The lower the viscosity, the faster the crystallization. Impurities. solid impurities are usually crystalline species for crystal growth, and the addition of certain precipitating pigment fillers can easily lead to crystallization. In contrast, larger particle sizes and higher additions are less likely to induce crystallization. Temperature. A narrow temperature cycle of 20-30°C is a common cause of crystallization, with diurnal temperature fluctuations initiating or accelerating the rate of crystallization. In addition, ultra-low temperatures (below 5°C) will accelerate crystallization. Moisture. The higher the moisture content, the more likely crystallization will occur.   Does crystallization affect the properties of epoxy resins? The crystallization phenomenon does not affect the performance of the epoxy resin, only the epoxy resin morphology has changed, not deterioration. However, it brings a lot of inconvenience to the operation. After practice, the crystalline epoxy resin is dissolved by heating and mixed with the corresponding proportion of curing agent, its tensile strength, flexural strength, compressive strength, and bonding strength have no change in comparison with epoxy resin without crystallization. It can be seen that the crystallization phenomenon does not affect the performance of the epoxy resin, only the epoxy resin morphology has changed, not a qualitative change. In general, the crystallization of epoxy resin adhesive is a reversible process that can be changed with the temperature and has no effect on the bonding performance and reinforcing effect of epoxy resin cured products. Even if the crystallization occurs, heating until it softens and disappears, it can be used normally.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. If you are interested in them, pls kindly contact us. We will be at service for you any time, thank you.  

Description Epoxy diluents are mainly used to reduce the viscosity of the epoxy adhesive system, dissolve and disperse and dilute the adhesive, and improve the coating and fluidity of the adhesive. Epoxy diluents also play a role in extending the service life. There are many ways to classify the diluent, according to its use mechanism, it can be divided into two categories of inactive diluent and active diluent.   Inactive diluents Inactive diluents do not contain active groups in their molecules and are mostly inert solvents. They do not react with epoxy resins, hardeners, etc. Inactive diluents are purely physically mixed into the resin. In addition to playing a diluting role, it has an impact on mechanical properties, heat distortion temperature, media resistance and aging damage. In the choice of inactive diluent should consider the solvent evaporation rate, if the evaporation rate is too fast, the surface of the adhesive layer is easy to form a film, preventing the adhesive layer of solvent inside the escape, resulting in bubbles in the adhesive layer. If the evaporation rate is too slow, the solvent remains in the adhesive layer, which will affect the strength of the bond. Usually, several solvents with different boiling points are mixed to regulate the evaporation rate. It is mostly used in rubber adhesive, phenolic adhesive, polyester adhesive and epoxy adhesive.   Reactive diluents Reactive diluents are generally low molecular compounds with one or two or more epoxy groups. They can be directly involved in the epoxy resin curing reaction, become part of the epoxy resin curing material crosslinking network structure. Reactive diluents have almost no effect on the properties of the cured product and can sometimes increase the toughness of the curing system. Active diluent is divided into monofunctional active diluent and difunctional active diluent. Active diluents are generally toxic and must be used with safety in mind. Prolonged contact will often cause skin irritation and in severe cases, even ulcers. Monofunctional active diluent dilution effect is better, aliphatic type has better dilution effect than aromatic type. The acid and alkali resistance of the curing products using aromatic active diluents does not change much, but the solvent resistance is reduced. The use of monofunctional reactive diluents will reduce the heat distortion temperature, which is due to its use will make the cured product crosslinking density decreased. Flexural strength and impact toughness are improved with long carbon chain active diluents. When used in small quantities, it has no effect on the hardness of the cured product, while the coefficient of thermal expansion increases.   Diluent selection principle Try to use active diluents, to improve the processability and at the same time improve its adhesive and mechanical properties. Choose those diluents that are similar to the chemical structure of the main resin. They will participate in the reaction with the main resin in the presence of other additives, and greatly improve the performance of the adhesive layer. Select low volatility, small odor and as low as possible toxicity varieties, to reduce the harm of using active diluent on the human body. Because most of the active or inactive diluents have odor and low toxicity. Should choose the source of easy, non-flammable and non-explosive, low-priced active diluent. Should be through the theory and experiments to choose the most appropriate amount to add.   We Nanjing Yolatech can provide a variety of high purity low chlorine epoxy resin active diluents, widely used in insulation materials, electronic potting, electrical casting and other fields, including 1,4-Butanediol diglycidyl ether(YLD-6018),1,6-Hexanediol diglycidyl ether (YLD-6008), Neopentyl glycol diglycidyl ether(YLD-6009), Neodecanoic acid glycidyl ester(YLD-8001) and so on.   Welcome new and old customers to consult at any time!    

  Epoxy resins are commonly used as a matrix for materials such as adhesives, coatings and composites, and are widely used in construction, machinery, electrical and electronic, aerospace and other fields. A complete concept of epoxy resin constituents by four aspects of the composition. However, in practice, it is not necessary to have all four aspects of the components, but the resin composition must include the curing agent, which shows the importance of the curing agent. Epoxy resin components Epoxy resin Epoxy resin Main part，bisphenol A type and other types of epoxy resins Curing agent Reacts with epoxy resins to form three-dimensional network polymers Components for modification Plasticiser Gives epoxy components plasticity, but reduces its heat and chemical resistance Toughening agent Improved impact resistance without compromising other properties Filler Increase weight, improve curability, mechanical properties, such as calcium carbonate, mica, etc Flame retardant agent To make the epoxy Components with flame resistance, there are filler flame retardant and reactive flame retardant Components used to regulate fluidity Diluent Reduce components viscosity, including active and inactive diluents Thixotropic agent Imparts thixotropic properties to epoxy compositions, e.g. asbestos, silica micropowder Other components Pigments, solvents, defoamers, levelling agents, tackifiers, etc. The reason why epoxy resins are widely used is the result of the versatile co-ordination of these components. Especially the curing agent, once the epoxy resin is determined, the curing agent plays a decisive role in the processability of the epoxy resin composition and the final performance of the cured product. Classification of epoxy curing agents 1. Classification by acid-base properties Type Curing agent name acidity Organic anhydrides, boron trifluoride and its complexes alkali Aliphatic diamines, polyamines, aromatic polyamines, dicyanodiamines imidazoles, modified amines   2. Classification by reactivity and chemical structure Curing agent Apparent curing agent Addition reaction Polyamine Simple amine Straight chain fatty amine DETA，TETA，DEPA，TEPA Polyamides Polyamides with different amine values Aliphatic amine MDA，IPDA Aromatic amine m-XDA, DDM, m-PDA, DDA Modified amine Anhydride Monofunctional group PA, THPA, HHPA, MeTHPA, MeHHPA, MNA, DDSA, HET Bifunctional group PMDA, BTDA, TMEG, MCTC Carboxyl group TMA, PAPA Polyphenol PN Polythiol PM, PS Catalyst reaction Anionic polymers DMP-30, 2E4MZ Cationic Polymers BF3∙MEA Latent curing agent Dicyandiamide Organic acid hydrazide Ketimine microcapsules   3. Classification by curing temperature Curing Temp. Curing agent type Curing agent name 0-20°C Low temperature curing agent Polythiols, aliphatic polyamines or promoters, aromatic polyamines or promoters 20-40°C Normal temperature curing agent Polyamide, tertiary amine 60-100°C Medium temperature curing agent Dibasic aminopropylamine, imidazole, tertiary amine salts, aliphatic amines 100-150°C Medium and high temperature curing agent Anhydride or promoter, BF3-ammonium salt, dicyandiamide/promoter, imidazole derivatives, hydrazides 150°C+ High temperature curing agent Aromatic polyamines, polyphenols, acid anhydrides   4. Classification by different usage Curing agent Curing at room temperature Heavy Duty Anti-corrosion Coatings Adhesives for civil engineering and construction Civil Engineering Coatings FRP General Adhesives Alicyclic polyamines Denatured polyamines Straight chain aliphatic polyamines Polyamides, polythiols Heat curing Electrically insulating material Acid anhydride, imidazoles, BF3 complexes Laminated materials Dicyandiamide, aromatic polyamines, linear phenolic resins Coatings   Tank materials Amino resins, methyl phenolic resins Powder material Dicyandiamide, aromatic polyamines, acid anhydrides Moulded material Linear phenolic resins Adhesives Aromatic polyamines, anhydrides, imidazoles, BF3 amine complexes     Structure and properties of curing agents A comprehensive understanding of the properties and characteristics of polyamine curing agents with the same functional group but different chemical structures is very important for the selection of curing agents. The main characteristics (color, ripeness, duration of use, etc.) also show a certain regularity. Color: (good) alicyclic->aliphatic->amide->aromatic amine(bad) Maturity: (low) alicyclic->aliphatic->aromatic->amide(high) Application period: (Long) Aromatic->Amide->Alicyclic->Aliphatic (Short Curability: (Fast) Aliphatic->Alicyclic->Amide->Aromatic (Slow) Irritation: (Strong) Aliphatic->Aromatic->Alicyclic-Amide (Weak) Gloss: (Excellent) Aromatic->Alicyclic->Polyamide->Aliphatic amide (Poor) Flexibility: (Soft) Polyamide->Aliphatic->Alicyclic->Aromatic (Rigid) Adhesion: (Excellent) Polyamide->alicyclic->aliphatic->aromatic (Good) Acid resistance: (Excellent) Aromatic->Alicyclic->Aliphatic->Polyamide (Inferior) Water Resistance: (Excellent) Polyamide->Aliphatic Amine->Aliphatic Cyclic Amine->Aromatic Amine (Good)     Development trend of curing agent Curing agent as a core substance to play the value of epoxy resin, the nature of the cured product depends on the performance of the curing agent, so the road of research on the curing agent has far-reaching significance. From the research of curing agent to date, combined with the current situation at home and abroad, curing agent is currently facing some of the following challenges and changes. The development of high activity and excellent heat resistance curing agent. The use of modified polyether amine, aliphatic amine or mixed compound to prepare high activity and heat resistance curing system. Due to the traditional epoxy resin in the curing performance is poor, especially low toughness, brittle, greatly affecting its use, so improve the performance of epoxy resin needs to improve the toughness. Improve the curing environment, overcome the volatility and toxicity of amine curing agent, and promote the development of room temperature curing agent by modifying amine with physical or chemical method. Improve the adaptability and specialty of epoxy resin in special environments, to meet the special environments such as humid, underground low temperature environment or underwater of reservoir dam repair. Curing agent and curing technology matching, will be a variety of curing technology (heat curing, microwave curing, light curing) combined with the selection of the appropriate curing agent may be able to get a comprehensive performance of the curing product. Heating type latent curing agent has great potential, can continue to study the dicyandiamide and its modified products, organic acid hydrazide, boron - amine complex, imidazole, microcapsules and other latent curing agent.

1. Indicators of epoxy groups This is the most important characteristic index of epoxy resin, which is used to indicate the content of epoxy group in the resin molecule, and there are three main ways of expression, including  epoxy value, epoxy index and epoxy equivalent. Epoxy value is defined as the amount of epoxy groups(mol) per 100g of epoxy resin，unit is mol/100g. The definition of the epoxy value is mainly for the purpose of calculating the amount of curing agent to be added to the epoxy resin for curing. The amount of curing agent is the mass of curing agent to be added per 100g of epoxy resin cured. Epoxy index is the amount of epoxy groups(mol) per 1kg of epoxy resin, the unit is mol/kg. In terms of the International System of Measurement (SI units), the epoxy index is more appropriate than the epoxy value, which is 10 times larger than the epoxy value. Epoxy equivalent is the mass (g) of an epoxy resin containing 1 mol of epoxy groups ,the unit is g/mol. The chain segments between the epoxy groups become longer and longer as the molecular weight of the epoxy resin increases, so the epoxy equivalent of epoxy resins with a high relative molecular mass is also elevated. The physical quantity of epoxy equivalent is usually used to describe the epoxy group of epoxy resin in the United States, Japan and Europe.   2. Hydroxyl content Bisphenol A-type epoxy resin molecular chain contains a large number of secondary hydroxyl structure, the larger the polymerization degree n value, its molecular weight is also larger, the higher the hydroxyl content. It can cross-link with phenolic resins, amino resins or Poly isocyanates, and it can promote the curing reaction. Therefore, when controlling the curing process of epoxy resin paint, the hydroxyl content of epoxy resin must be determined. There are two most used methods to express the hydroxyl content. The hydroxyl value F is the amount of hydroxyl contained in 100g of epoxy resin, the unit is mol/100g. And the hydroxyl equivalent H is the mass(g)of epoxy resin containing 1mol of hydroxyl, the unit is g/mol.   3. Softening point Epoxy resin is a mixture of homologous prepolymers with different degrees of polymerization and has no fixed melting point or melting process. The softening point generally refers to the temperature at which the epoxy resin turns from hard to soft and shows a certain fluidity in the process of heating. The softening point of epoxy resin can characterize the average molecular weight size and distribution of the resin, the molecular weight of the high softening point is large, and the molecular weight of the low softening point is small. Epoxy resins can be broadly classified according to the softening point into three types. Type Softening point Degree of polymerisation Low molecular weight epoxy resin <50°C <2 Medium molecular weight epoxy resin 50~95°C 2~5 High molecular weight epoxy resin >100°C >5     4. Viscosity The viscosity of epoxy resins affects the fluidity and workability of resins and coatings. Viscosity increases as the average molecular weight of the epoxy resin increases and decreases as the molecular weight distribution decreases. The viscosity of epoxy resins is extremely sensitive to temperature and decreases rapidly with increasing temperature, so it is generally expressed as the viscosity at a specific temperature.   5. Chlorine value The amount of chlorine contained in an epoxy resin (including organic chlorine and inorganic chlorine) is called the chlorine value. The chlorine in the epoxy resin is divided into organic chlorine and inorganic chlorine by the form of its existence. Organic chlorine comes from the residue of insufficient ring closure in the manufacture of the epoxy resin, which is called easily hydrolysable chlorine. Inorganic chlorine comes from the residual sodium chloride that is not washed sufficiently when manufacturing epoxy resins. Organic chlorine measures the resin reaction, and inorganic chlorine measures the level of post-production treatment processes for epoxy resins. Both are detrimental to the electrical properties of the cured substance and to corrosion resistance.