What are the effects of curing agents on epoxy resin molding? 20

The more hardener, the longer the curing time.

1 Epoxy latent curing agent.

Modified aliphatic amines.

Aliphatic amine curing agents such as ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, etc. are commonly used two-component epoxy resin room temperature curing agents, through chemical modification methods, they are nucleophilic addition reaction with organic ketones compounds, and dehydration to form imine is an effective way to block, reduce its curing activity, and improve its storage stability.

Aromatic diamines.

Aromatic amines are valued due to their high TG, but their application is limited due to their high toxicity. The modified aromatic diamine curing agent has the advantages of high TG, low toxicity, low water absorption and good comprehensive performance.

Cyandiamides. Dicyandiamine, also known as dicyanediamine, has long been used as a latent curing agent in powder coatings, adhesives and other fields. After mixing dicyandiamide with epoxy resin, the storage period at room temperature can be as long as half a year. The curing mechanism of dicyandiamide is complex, in addition to the four hydrogens on dicyandiamide that can participate in the reaction, the cyano group also has a certain reactivity.

When dicyandiamide is used as an epoxy curing agent alone, the curing temperature is very high, generally between 150 and 170, at this temperature many devices and materials cannot be used because they cannot withstand such temperatures, or the curing temperature of one-component epoxy resin must be reduced because of the requirements of the production process. There are two ways to solve this problem, one is to add an accelerator to reduce the curing temperature of dicyandiamide without impairing its storage life and performance. There are many such accelerators, mainly imidazoles and their derivatives and salts, urea derivatives, organic guanidine derivatives, phosphorus-containing compounds, transition metal complexes and composite accelerators, etc., these accelerators can significantly reduce the curing temperature of dicyandiamide, and the ideal curing temperature can be reduced to about 120, but at the same time, the storage period will be shortened, and the water resistance will also be affected to a certain extent.

The curing agents of epoxy resins are mainly polyamines and polyacids or anhydrides.

1) Polyamine curing agents are mainly diethylenetriamine and triethylenetetramine, which react quickly with epoxy groups and have high crosslinking density.

2) The use of polyacids is also common, such as trimellitic acid or trimellitic anhydride, trimellitic acid or trimellitic anhydride, etc.

3) Amino resins and carboxyl resins can also be used as curing agents for epoxy resins.

<> epoxy resin curing agent is made of phenol, formaldehyde, ethylenediamine, p-tert-butylphenol, n-butanol glycidyl ether, polypropylene glycidyl ether and other raw materials. Commonly used epoxy resin curing agents are aliphatic amines, aliphatic cyclic amines, aromatic amines, polyamides, anhydrides, resins, tertiary amines, general ultraviolet rays or light can make epoxy resin cure, epoxy resin curing basically does not produce low molecular volatiles, so it can be low-pressure molding or contact pressure molding.

1. Curing agent formula epoxy resin

1. Epoxy resin curing agent formula: phenol, formaldehyde, ethylenediamine, p-tert-butylphenol, n-butanol glycidyl ether, polypropylene glycidyl ether. Epoxy resin curing agent is mainly used in the field of adhesive material technology, which has low temperature resistance, waterproof and other special conditions.

2. The commonly used epoxy resin curing agents are aliphatic amines, aliphatic cyclic amines, aromatic amines, polyamides, anhydrides, resins, tertiary amines, and ultraviolet and light can cure epoxy resin. If normal temperature or low temperature curing is required, amine curing agents can be used, and acid anhydride and aromatic curing agents can be used for heating curing.

3. Epoxy resin will not produce low molecular volatiles when curing, so it can be molded under low pressure or contact pressing. In addition, it can be combined with various curing agents to create solvent-free, high-solids, powder coatings and water-based coatings and other environmentally friendly coatings.

Second, the role and use of epoxy resin

1. Use: As a coating, epoxy resin is used in coatings, and it can be made into varieties with different characteristics and uses. Function: It has good chemical resistance, especially alkali resistance, good heat resistance and electrical insulation, and good color retention of paint film.

2. Epoxy resin refers to the general term of polymers containing more than two epoxy groups in the molecule, which is the product of epichlorohydrin and bisphenol A or polyol. Because the epoxy group has a certain chemical activity, it can be used with a variety of active hydrogen compounds to open the ring, solidify and cross-link to form a network structure, so it is a thermosetting resin.

3. There are many feres of epoxy resin, if classified according to professional use, it can be divided into mechanical epoxy resin adhesive, construction epoxy resin adhesive, electronic epoxy resin adhesive, repair epoxy resin adhesive, traffic adhesive, marine adhesive, etc.

Curing agent, commonly known as hardener, curing agent or metastabilizer, is a class of substances or mixtures that enhance or control the curing reaction. While it improves the hardness of the ground, it can also improve its wear resistance and waterproofing effects. What are the classifications of curing agents?

What is the function of an epoxy curing agent? Let's learn about the classification of epoxy resin curing agents and the number of reputation roles of epoxy resin curing agents.

Epoxy resin curing agent.

1. Classification of epoxy resin curing agent.

1. Classification by use.

Curing agents can be divided into room temperature curing agents and heating curing agents according to their uses. The difference between the two is that the room temperature curing agent is suitable for fields without heating process, while the high temperature curing agent can release the isocyanate group during heat treatment and react with the hydroxyl group and other groups on the molecular chain of the water-based resin to form a cross-linked structure, which can significantly improve the performance of the water-based resin.

2. Classified according to chemical composition.

According to the classification of chemical composition, it can be divided into aliphatic amines, aromatic amines, amide amines, latent curing amines, and urea substitutes. These types vary depending on the chemical composition in the field of use.

Epoxy resin curing agent construction.

Second, the role of epoxy resin curing agent.

The performance of epoxy resin curing at high temperature is relatively good, but it is difficult to use materials such as coatings in the construction industry when heating, so it needs to be cured at room temperature, and the effect of epoxy resin curing agent is particularly obvious. Epoxy resin curing agent is widely used in electronics, electrical appliances and other aspects.

In the classification of epoxy resin curing agents, aliphatic polyamine cures have excellent adhesion, alkali and water resistance, and aromatic polyamines are also excellent in terms of product resistance. Since the nitrogen element in the curing agent component forms hydrogen bonds with the metal, it also has an excellent anti-rust effect.

The role of epoxy resin curing agent.

The above is the classification of epoxy resin curing agent and the role of epoxy resin curing agent for you to share or enjoy, I hope it will help you. If you want to know more about the void cavity of epoxy resin curing agent, please stay tuned.

Generally, epoxy resin E 51: The curing agent is 100:50, but some of the curing agents are 100:

40, there are also lower or higher. For example, 100:20 or 100:

60。Normally, it is desirable to have as low a curing agent ratio as possible, because the cost is lower (because the curing agent is expensive).

Amine dosage = mg hn.

m = amine molecular weight.

hn = number of active hydrogen.

g = epoxy value (number of epoxy equivalents contained in 100 grams of epoxy resin).

When using anhydrides, it is calculated as follows:

Acid anhydride dosage = mg (where:

m = anhydride molecular weight.

g = epoxy value (is the experimental coefficient.)

Epoxy resin curing agent is a chemical reaction with epoxy resin to form a network of three-dimensional polymers, which envelops the composite bone in the network. It is an additive that turns linear resin into a tough body-shaped solid. There are many types included.

Classification of epoxy resin curing agents: (1) Alkaline and acidic curing agents Alkaline curing agents include aliphatic diamines and polyamines, aromatic polyamines, other nitrogen-containing compounds and modified aliphatic amines. Acidic curing agents include organic acids, anhydrides, and boron trifluoride and their complexes.

2) Additive and catalytic curing agent Additive curing agent This kind of curing agent undergoes an addition reaction with the epoxy group to form a part of the chain segment of the curing product, and cross-links the linear molecules into bulk structure molecules through a gradual polymerization reaction, which is also known as melon-type curing agent. Catalytic curing agent This type of curing agent only initiates the epoxy resin, and after the epoxy group is opened, the catalytic epoxy resin itself polymerizes into a network structure to form a homopolymer with ether bonds as the main structure. (3) Visible curing agent and latent curing agent Visible curing agent is a commonly used curing agent, which can be divided into addition polymerization type and catalytic type.

The so-called addition polymerization type is to open the ring of the epoxy group for addition polymerization reaction, and the curing agent itself participates in the three-dimensional network structure. If the amount of this kind of curing agent is too small, the curing product is connected to the epoxy group of the final reaction. Therefore, there is a suitable dosage for this type of curing agent.

The catalytic curing agent is made by ring-opening addition polymerization of epoxy groups in cationic or anionic mode, and in the end, the curing agent does not participate in the network structure, so there is no suitable amount of equivalent reaction; However, increasing the dosage will result in a faster curing rate. Latent curing agent refers to the relative long-term stability at room temperature after mixing with epoxy resin (an epoxy resin generally requires more than 3 months to have great practical value, and the most ideal requires half a year or more than 1 year), and only needs to be exposed to heat, light, moisture and other conditions to start the curing reaction. This type of curing agent basically seals the activity of the curing agent by physical and chemical methods.

Among the obvious curing agents, varieties such as dicyandiamide and adipic acid hydrazide are insoluble in epoxy resin at room temperature, and begin to solidify after dissolving at high temperature, so they also show a latent state. Therefore, in some books, these varieties are also classified as latent curing agents, which can actually be called functional latent curing agents. Because the latent curing agent can be mixed with epoxy resin to make a one-liquid complex, simplifying the application procedures of epoxy resin, its application range from single packaging adhesive to coatings, impregnating paints, potting materials, powder coatings and other aspects.

Latent curing agent has attracted more and more attention in foreign countries, which can be said to be a key topic in research and development.