[Edit this paragraph] Application features
1, various forms. Various resin, curing agent and modifier systems can meet the requirements of almost all kinds of applications, from extremely low viscosity to high melting point solids.
2, the curing is convenient. With different curing agents, the epoxy resin system can be cured almost in the temperature range of 0 ~ 180℃.
3. Strong adhesion. The existence of polar hydroxyl groups and ether bonds in the molecular chain of epoxy resin makes it have high adhesion to various substances. When epoxy resin is cured, the shrinkage rate is low and the internal stress is small, which also helps to improve the bonding strength.
4. Low shrinkage. The reaction between epoxy resin and curing agent is carried out by direct addition reaction or ring-opening polymerization reaction of epoxy groups in resin molecules, and no water or other volatile by-products are released. Compared with unsaturated polyester resin and phenolic resin, they show very low shrinkage (less than 2%) during curing.
5. Mechanical properties. The cured epoxy resin system has excellent mechanical properties.
6. Electrical performance. The cured epoxy resin system is an excellent insulating material with high dielectric properties, surface leakage resistance and arc resistance.
7. Chemical stability. Generally, the cured epoxy resin system has excellent alkali resistance, acid resistance and solvent resistance. Like other properties of cured epoxy system, chemical stability also depends on the selected resin and curing agent. Proper selection of epoxy resin and curing agent can make it have special chemical stability.
8. Dimensional stability. The combination of the above properties makes the epoxy resin system have outstanding dimensional stability and durability.
9, anti-mold. The cured epoxy resin system can resist most molds and can be used in harsh tropical conditions.
[Edit this paragraph] Type classification
According to the molecular structure, epoxy resins can be roughly divided into five categories:
1, glycidyl ether epoxy resin
2. glycidyl ester epoxy resin
3, glycidyl amine epoxy resin
4. Linear aliphatic epoxy resin
5. cycloaliphatic epoxy resin
The glycidyl ether epoxy resin is the most widely used epoxy resin in composite materials industry, among which diphenol propane epoxy resin (bisphenol A epoxy resin for short) is the main one. Followed by glycidyl amine epoxy resin.
1, glycidyl ether epoxy resin
Glycidyl ether epoxy resin is formed by polycondensation of phenol or alcohol containing active hydrogen and epichlorohydrin.
(1) bisphenol propane epoxy resin bisphenol propane epoxy resin is formed by polycondensation of bisphenol propane and epichlorohydrin.
Industrial diphenol propane epoxy resin is actually a mixture of molecules with different polymerization degrees. Most molecules are linear structures with two epoxy groups. Some molecules may be branched and the groups terminated by very few molecules are chlorohydrin groups instead of epoxy groups. Therefore, the epoxy group content and chlorine content of epoxy resin have great influence on the curing of resin and the properties of cured products. The industrial control indexes of resin are as follows:
① Epoxy value. Epoxy value is the most important index to identify the performance of epoxy resin, and industrial epoxy resin models are distinguished according to the different epoxy values. Epoxy value refers to the amount of substances containing epoxy groups per 100g resin. The epoxy value multiplied by the reciprocal of 100 is called epoxy equivalent. The meaning of epoxy equivalent is: grams of epoxy resin containing 1mol epoxy group.
② Inorganic chlorine content. Chloride ion in resin can complex with amine curing agent, which affects the curing of resin and the electrical properties of cured resin, so chlorine content is also an important index of epoxy resin.
③ Organic chlorine content. The content of organochlorine in the resin indicates the content of chlorohydrin groups in the molecule that have not undergone ring-closing reaction, and its content should be reduced as much as possible, otherwise it will also affect the curing of the resin and the properties of the cured products.
④ Volatile substances.
⑤ Viscosity or softening point.
(2) Phenolic polyepoxy resin Phenolic polyepoxy resins include phenolic and o-cresol-formaldehyde polyepoxy resins. Compared with bisphenol-propane epoxy resin, its linear molecule contains more than two epoxy groups, so the cured product has high crosslinking density and excellent thermal stability, mechanical properties, electrical insulation, water resistance and corrosion resistance. They are formed by polycondensation of novolak resin and epichlorohydrin.
(3) Other practical representatives of polyhydroxyphenol glycidyl ether epoxy resin are resorcinol epoxy resin, resorcinol-formaldehyde epoxy resin, tetraphenolethane epoxy resin and trihydroxyphenylmethane epoxy resin. These multifunctional glycidyl ether resins have high thermal deformation temperature and rigidity after curing, and can be used alone.
Or mixed with general E-type resin * * * for matrix materials such as high-performance composite materials (ACM) and printed circuit boards.
(4) glycidyl ether epoxy resins of aliphatic polyols contain two or more epoxy groups in their molecules, and most of these resins have very low viscosity; Most of them are long-chain linear molecules, so they are flexible
2. Other types of epoxy resin
(1) glycidyl ester epoxy resin has lower viscosity and better workability than diphenol propane epoxy resin. High reaction activity; The adhesion is higher than that of ordinary epoxy resin, and the cured product has good mechanical properties; Good electrical insulation; It has good weather resistance and ultra-low temperature resistance, and it still has higher bonding strength than other types of epoxy resin under ultra-low temperature conditions. It has good surface gloss, light transmittance and weather resistance.
(2) glycidyl amine epoxy resin has the advantages of high functionality, high epoxy equivalent, high crosslinking density and significantly improved heat resistance. At home and abroad, glycidyl amine epoxy resin has been used to manufacture carbon fiber reinforced composites (CFRP) for aircraft secondary structural materials due to its excellent adhesion and heat resistance.
(3) alicyclic epoxy resin This kind of epoxy resin is prepared by epoxidizing the double bonds of alicyclic olefins. Their molecular structures are quite different from those of bisphenol-propane epoxy resin and other epoxy resins. The epoxy group of the former is directly connected to the alicyclic ring, while the epoxy group of the latter is all connected to the benzene core or aliphatic hydrocarbon with epoxy propyl ether. The cured products of alicyclic epoxy resin have the following characteristics: ① high compressive and tensile strength; ② Good mechanical properties can still be maintained after long-term exposure to high temperature; ③ Good arc resistance, ultraviolet aging resistance and weather resistance.
(4) The molecular structure of epoxy resin such as aliphatic epoxy resin has neither benzene core nor alicyclic structure. Only the fatty chain and the epoxy group are connected to the fatty chain. The cured epoxidized polybutadiene resin has good strength, toughness, adhesion and positive and negative temperature resistance.
[Edit this paragraph] User Guide
Epoxy resin and epoxy resin adhesive are non-toxic, but many epoxy resins are "toxic" because solvents and other toxic substances are added in the preparation process. In recent years, the domestic epoxy resin industry is trying to maintain the "non-toxic" nature of epoxy resin by water-based modification and avoiding addition. At present, the vast majority of epoxy resin coatings are solvent-based coatings, which contain a large number of volatile organic compounds (VOC), are toxic and flammable, and do harm to the environment and human body.
Epoxy resin is generally used with additives at the same time to obtain application value. Additives can be selected according to different uses. Commonly used additives are: (1) curing agent; (2) modifiers; (3) filler; (4) diluent; (5) others.
Curing agent is an essential additive, and curing agent should be added whether it is used as adhesive, coating or castable, otherwise epoxy resin cannot be cured.
Due to different performance requirements, the requirements for epoxy resin and additives such as curing agent, modifier, filler and diluent are also different. Now their selection methods are briefly introduced as follows:
(A) the choice of epoxy resin
1, select from use
It is best to use resin with medium epoxy value (0.25-0.45) as adhesive, such as 6101.634; It is best to choose resins with high epoxy value (> 0.40), such as 6 18, 6101; Low epoxy value (
2. Choose from the mechanical strength.
The resin with too high epoxy value has higher strength, but it is fragile; Good high and low temperature strength and moderate epoxy value; The lower the epoxy value, the worse the high temperature strength. Because the strength is related to the degree of crosslinking, the degree of crosslinking is also high after curing with high epoxy value, and the degree of crosslinking is also low after curing with low epoxy value, resulting in the difference of strength.
3, choose from the operational requirements
Does not need high temperature resistance, and has little requirement on strength. It is hoped that the epoxy resin will dry quickly and is not easy to lose, and the resin with lower epoxy value can be selected. If permeability and strength are needed, a resin with higher epoxy value can be selected.
(2) Selection of curing agent
1, curing agent type:
Curing agents commonly used for epoxy resins include aliphatic amines, cycloaliphatic amines, aromatic amines, polyamides, anhydrides, resins and tertiary amines. In addition, under the action of photoinitiator, ultraviolet or light can also cure epoxy resin. Amine curing agents are generally used for curing at room temperature or low temperature, while anhydrides and aromatic curing agents are generally used for heating curing.
Epoxy value is the most important index to identify the quality of epoxy resin, and the types of epoxy resin are divided according to the different epoxy values. Epoxy value refers to the number of gram equivalents of epoxy groups contained in100g resin.
2, the dosage of curing agent
When (1) amine is used as crosslinking agent, its calculation is as follows:
Amine dose =MG/Hn
Among them:
M= molecular weight of amine
Hn= number of active hydrogen.
G= epoxy value (number of epoxy equivalents contained in epoxy resin per 100g)
The range of change shall not exceed 10-20%. If excessive amine is used to cure the resin, it will make the resin brittle. If the dosage is too small, the curing is not perfect.
(2) When acid anhydride is used, it is calculated according to the following formula:
Anhydride dosage = mg (0.6 ~1)100, where:
M= molecular weight of anhydride
G= epoxy value (0.6~ 1) is the experimental coefficient.
3. Selection principle of curing agent: Curing agent has great influence on the performance of epoxy resin, and it is generally selected according to the following points.
(1), from the performance requirements: some require high temperature resistance, some require good flexibility, and some require good corrosion resistance, so we should choose the appropriate curing agent according to different requirements.
(2) Selection of curing method: Some products can't be heated, so you can't use thermosetting curing agent.
(3) Selection of applicable period: The so-called applicable period refers to the time from the addition of epoxy resin as curing agent to the unavailability. For long-term applications, anhydrides or potential curing agents are usually selected.
(4) Safety selection: Generally speaking, the smaller the toxicity, the better, which is convenient for safe production.
(5), choose from the cost.
(3) The choice of modifiers
The purpose of the modifier is to improve the tannage, shear resistance, bending resistance, impact resistance and insulation performance of epoxy resin. Commonly used modifiers are:
(1), polysulfide rubber: can improve impact strength and peeling resistance.
(2) Polyamide resin: It can improve brittleness and improve adhesion.
(3) Polyvinyl tert-Butyraldehyde: Improve the impact tanning resistance.
(4) NBR: improve the impact tanning resistance.
(5) Phenolic resin: It can improve the temperature resistance and corrosion resistance.
(6) Polyester resin: improve the impact tanning resistance.
(7) Urea-formaldehyde melamine resin: increase chemical resistance and strength.
(8) Furfural resin: improve static bending performance and acid resistance.
(9) Vinyl resin: improve peeling resistance and impact strength.
(10), isocyanate: reduce moisture permeability and increase water resistance.
(1 1), silica gel: improve heat resistance.
The dosage of polysulfide rubber can be between 50% and 300%, and vulcanizing agent is needed; The dosage of polyamide resin and phenolic resin is generally 50- 100%, and the dosage of polyester resin is generally 20-30%. No additional curing agent can be added, or a small amount of curing agent can be added to accelerate the reaction.
Generally speaking, the more modifier is used, the greater the flexibility, but the thermal deformation temperature of resin products decreases accordingly.
In order to improve the flexibility of resin, toughening agents such as dibutyl phthalate or dioctyl phthalate are also commonly used.
(4) Selection of fillers
The function of filler is to improve some properties of products and heat dissipation conditions when resin is cured. The use of fillers can also reduce the amount of epoxy resin and reduce the cost. Different fillers can be selected for different purposes. Its size is preferably less than 100 mesh, and the dosage depends on the use. Brief introduction of commonly used fillers is as follows:
The function of filling in the name
Asbestos fiber and glass fiber increase toughness and impact resistance.
Quartz powder, porcelain powder, iron powder, cement and emery improve hardness.
Alumina and porcelain powder increase adhesion and mechanical strength.
Asbestos powder, silica gel powder and high temperature cement improve heat resistance.
Asbestos powder, quartz powder and stone powder reduce shrinkage.
Metal powders such as aluminum powder, copper powder and iron powder increase thermal conductivity and electrical conductivity.
Graphite powder, talcum powder and quartz powder improve the wear resistance and lubrication performance.
Emery and other abrasives improve wear resistance.
Mica powder, porcelain powder and quartz powder increase insulation performance.
All kinds of pigments and graphite have colors.
In addition, it is reported that an appropriate amount (27-35%) of oxides of P, AS, Sb, Bi, Ge, Sn and Pb can be added to the resin to maintain adhesion under high heat and pressure.
(5) Selection of diluents
Its function is to reduce viscosity and improve the permeability of resin. Diluents are divided into two categories: inert and active, and the dosage is generally not more than 30%. Commonly used diluents are as follows:
Active diluent
Remarks on Name, Brand and Purpose
600 ~30% diglycidyl ether needs more curing agent.
Polyglycidyl ether 630 ditto ditto
Propylene oxide butyl ether 660 ~ 15% same as above.
Glycidyl phenyl ether 690 ditto ditto
Dipropylene oxide ether 669 ditto ditto
Propylene oxide propyl ether 662 ditto ditto
Inert diluent
Name and Dose Remarks
Xylene ~ 15% does not need additional curing agent.
Toluene ditto ditto
Benzene ditto ditto
Acetone ditto ditto
Before adding curing agent, all materials such as resin, curing agent, filler, modifier and diluent used must be inspected and meet the following requirements:
(1), no moisture: materials containing moisture should be dried first, and solvents containing a small amount of moisture should be used as little as possible.
(2) Purity: The content of impurities except water is preferably below 65438 0%. If the impurity is 5-25%, it can be used, but the percentage of the formula should be increased. It is better to use reagent grade when the dosage is small.
(3), understand whether the material failure.
In factories lacking acceptance conditions, it is best to make a sample test according to the formula before use.
(6) Three stages of curing
1. Liquid operation time
Operating time (also called working time or service life) is a part of curing time. After mixing, the resin/curing agent mixture is still liquid, working and suitable for application. In order to ensure reliable bonding, all construction and positioning work should be done well within the curing operation time.
2. Gel curing
The mixture begins to enter the curing stage (also known as maturity), when it begins to gel or "mutate". At this time, the epoxy will not work for a long time and will lose its viscosity. We can't disturb at this stage. It will become a soft gel like hard rubber and can be pressed with your thumb.
Because the mixture is only partially cured at this time, the newly used epoxy resin can still be chemically linked with it, so the untreated surface can still be bonded or reacted. In any case, these abilities are declining for mixtures that are close to solidification.
3. The solid is finally solidified
The epoxy resin mixture reaches the curing and solid stage, at which time it can be polished and molded. You can't press with your thumb at this time. At this time, the final reaction strength of epoxy resin is about 90%, so the fixing clip can be removed and left at room temperature for several days to continue curing.
At this time, the newly used epoxy resin can not be chemically bonded with it, and the epoxy surface must be properly pretreated, such as polishing, to obtain good bonding mechanical strength.
[Edit this paragraph] Major domestic manufacturers
1, Baling Petrochemical Company (Epoxy Resin Division)
2. Blue Star New Material Wuxi Resin Factory
3. Dalian Qihua Company
4. Jiangsu Sanmu Group Company
5. South Asia Epoxy Resin (Kunshan) Co., Ltd.
6. Dow Zhangjiagang Company
Guangzhou hongchang electronic material industry co., ltd.
8. Guodu Chemical Kunshan Company
9. Huntsman Advanced Materials Company
10, Tao Jian Chemical Industry Group
1 1, Wuxi Deaisheng Company
12, Changchun Chemical (Jiangsu) Co., Ltd.
13, Jiangsu Yangnong Chemical Group Co., Ltd.
14, Nanjing Aosang Painting Engineering Co., Ltd.
[Edit this paragraph] Application field of epoxy resin
1. In the field of coatings
Used in automobile: chassis primer, component paint, inner wall paint of tanker.
Used for containers: coatings on the inner and outer walls of food tanks, anticorrosive coatings on the inner and outer walls of storage tanks, and anticorrosive coatings on pressure tanks.
Used for factory equipment: anti-corrosion coating for equipment and pipelines, external coating for refrigerators and washing machines, and insulation coating for electrical equipment.
Used in civil engineering: anti-corrosion coatings for bridges, anti-corrosion coatings for steel structures, anti-seepage coatings for cement products, floor coatings, decorative coatings, functional coatings and steel mesh cement gates.
Used for ships: inner wall coating of bottom warehouse, marine container coating, steel corrosion protection coating.
Other applications: powder coating for steel furniture, powder coating for resistance elements, powder coating for steel parts, anti-corrosion and heavy-duty wear-resistant ceramics for valve bodies, shielded vertical pipeline pumps, solar water heaters, solar panels and weapons.
2. In the field of composite materials
Used in automobile: FRP automobile shell, FRP floor, FRP tanker, control system instrument and electrical parts, display, automobile dry ignition coil, FRP parts, anti-slip particle steering wheel cover, epoxy resin local reinforcement material,
Equipment used in the factory: glass fiber reinforced plastic oxygen cylinders, glass fiber reinforced plastic storage tanks, glass fiber reinforced plastic containers, pipes, molds, propellers, looms, aircraft honeycomb structural parts, engine covers, rollers, shafts, leveling of installation foundations, self-leveling floors, electromagnetic coils, pilot valves, glass parts, glass fiber reinforced plastic pump valves, electric carbon products, construction engineering structural parts and machine transmission parts.
Insulating materials: copper clad laminate, glass steel plate, tube, rod, transformer, relay, high voltage switch, insulator, transformer, impedance device, cable head, sealing or plastic sealing of electronic devices and components, alarm, solid power supply, FBT flyback transformer, focusing potentiometer, ignition coils of motorcycles, automobiles and other motor vehicles, electronic and electrical parts, light-emitting diodes, signal lamps and full sealing. Temperature transmitter, tape recorder head, circuit board seal, integrated circuit, diode and triode discrete devices, passive filter, LED structure package, packaged solar panel, power module, IC regulator and solid-state relay, coal mine safety detection system, intrinsically safe module and automatic recloser.
Used for sporting goods: FRP helmet, racket, golf club, fishing rod, bowling, sleigh, surfboard, FRP rowing boat, sailing boat, racing car, lounge chair and hockey stick.
Used in other fields: aircraft fuselage, helicopter spiral blades, wind turbine blades, medical instruments, surgical handles, cardiac pacemakers, handicrafts and jewelry, valve seals, water conservancy construction projects, electroluminescent screens, concrete wear-resistant layers, thermal insulation materials, animal models, spacecraft, ship stern shafts, rudder shafts, chemical wood, iron tower reinforcement, maglev train tracks, solar cell musical instruments, epoxy resin decorations.
3. In the field of adhesives
Applications: room-temperature fast curing tough epoxy resin adhesive, conductive adhesive, room-temperature curing electrostatic flocking adhesive, optical structural adhesive, shuffleboard adhesive, chemical anchoring adhesive, silk functionalization, artificial flowers, magnetic writing boards, automobile maintenance adhesive and stone adhesive.
[Edit this paragraph] Epoxy resin industry
With the rapid and stable development of China's national economy, the epoxy resin industry has also made great progress. From the end of 20th century to today's rapid development, China's epoxy resin industry only took more than five years, during which the output increased from 60,000 tons in 2000 to more than 300,000 tons in 2005. Consumption increased from 6,543,800,000 tons in 2000 to 650,000 tons in 2005, with an average annual increase of 30%. In fact, China has become the main growth force of epoxy resin in the world, pushing the global epoxy resin industry to maintain high growth.
There are many domestic manufacturers of epoxy resin, but there are few enterprises above 10,000 tons. The main producers of epoxy resin in China are Guangzhou Hongchang Electronic Materials Industry Co., Ltd., Baling Petrochemical Transocean Petrochemical General Factory, Bluestar Chenxing New Materials Co., Ltd., Guangdong Ciba Polymer Chemical Co., Ltd., Jiangsu Sanmu Group Company, Dalian Qihua Chemical Co., Ltd., Wuxi Di Aisheng Epoxy Co., Ltd., etc.
From 65438 to 0996, China imported 40,800 tons of epoxy resin, reaching 260,000 tons in 2005, with an average annual growth rate of more than 20% in nine years, with a very fast growth rate. With the rapid increase of domestic production capacity, the import volume has gradually remained stable since 2004. While the production capacity of domestic epoxy resin enterprises has increased, the export volume of epoxy resin in China has increased year by year, from 8600 tons in 1996 to 778 tons in 2005.
Compared with foreign advanced technology, there is still a certain gap in the production technology of most domestic epoxy resin enterprises. The main problems are that the scale of production equipment is not economical enough, the product specificity is low, and the product quality stability is poor. In addition, the convenience of after-sales service and application of products also needs to be improved.
Nevertheless, the huge market potential still provides a space for domestic enterprises to survive and develop. It is predicted that the epoxy resin production capacity in China will further increase in the future. In the next 5- 10 years, China's epoxy resin industry will be further standardized, and enterprises with high production costs, unqualified environmental protection and low product grade will be eliminated. By 20 10, China's epoxy resin production capacity will remain at 600,000-700,000 tons, and there is still a certain gap in the domestic market. At the same time, the accelerated development of domestic pillar industries has brought infinite business opportunities to the epoxy resin industry, such as automobile industry, information industry, energy, transportation and construction industry. These pillar industries, which are in the ascendant, are all fields of application of epoxy resin, which will bring huge market demand to epoxy resin.