How Much Do You Know About Shoe Curing Agents?

　　 Curing temperature and heat resistance of curing agent

Various curing agent The curing temperatures are different, and the heat resistance of cured products is also very different. Generally speaking, curing agents with high curing temperature can get good curing properties with excellent heat resistance. For addition polymerization curing agents, the curing temperature and heat resistance are increased in the following order:

Aliphatic polyamines <; aliphatic polyamines <; aromatic polyamine phenolic aldehyde anhydride.

The heat resistance of the catalytic polymerization curing agent is generally at the level of aromatic polyamine. The heat resistance of anionic polymerization (tertiary amine and imidazolized antiquities) and cationic polymerization type (BF3 complex) are basically the same. This is mainly due to the different initial reaction mechanisms, but eventually the network structure of ether bond is formed.

The curing reaction belongs to the chemical reaction, which is greatly influenced by the curing temperature, the temperature is increased, the reaction speed is accelerated, the gel time is shorter, and the gelation time value generally decreases linearly with the increase of curing temperature. However, the curing temperature is too high, which often degrades the properties of the cured products, so there is the upper limit of curing temperature. It is necessary to choose the temperature which makes the curing speed and the properties of the curing material compromise as the suitable curing temperature. According to curing temperature, curing agents can be divided into four categories: low temperature curing agent curing temperature below room temperature; room temperature curing agent curing temperature at room temperature to 50 degrees; moderate temperature curing agent is 50~100 degrees; high temperature curing agent curing temperature above 100 degrees Celsius. Curing agent belonging to low temperature curing type Varieties In recent years, T-31 modified amines and YH-82 modified amines made in China can be solidified below 0 degrees Celsius. There are many types of room temperature curing: aliphatic polyamines, aliphatic polyamines, low molecular polyamides and modified aromatic amines. There are a number of alicyclic polyamines, tertiary amines, imidazole and three boron fluoride complexes. High temperature curing agents include aromatic polyamines, anhydride, phenolic resin, amino resin, dicyandiamide and hydrazide.

For high temperature curing system, the curing temperature is generally divided into two stages. The gel is solidified at low temperature before reaching the gel state or slightly higher than the gel state. Then the post-cure is solidified at high temperature and solidified as pre curing (pre-cure).

　　 Structure and characteristics

The curing temperature of the curing agent is closely related to the heat resistance of the cured product. Similarly, in the same curing agent, although they have the same functional groups, their properties and curing properties are different due to their different chemical structures. Therefore, a comprehensive understanding of the properties and characteristics of polyamine curing agents with the same functional groups and different chemical structures is very important for selecting curing agents.

In terms of hue, the alicyclic group is the shallower and basically transparent, while the aliphatic and aromatic colors are quite significant. In terms of viscosity, it is also very different. Aliphatic race is only 0.5 Pa / s, while polyamide is very sticky, amounting to Pa. S, aromatic amine is solid. The duration of application is exactly opposite to that of curing, the aliphatic reaction is the highest, while the aliphatic group, amide and aromatic group decrease in turn.

Hue: (excellent) aliphatic group, aliphatic, amide, aromatic amine (inferior)

Maturity: (low) alicyclic to aliphatic aromatic aromatic amide (high)

Application period: (long) aromatic group, amide group, aliphatic group, aliphatic group (short)

Curing: (fast) aliphatic to alicyclic to amide to aromatic (slow)

Irritation: (strong) aliphatic to aromatic group to aliphatic group to amide (weak)

　　 Chemical structure and properties of polyamine curing agents

In addition, it has certain regularity in gloss, softness, adhesion, acid resistance and water resistance.

Gloss: (excellent) aromatic to alicyclic to polyamide fatty amine (inferior)

Softness: (soft) polyamide to aliphatic to alicyclic to aromatic (rigid)

Adhesion: (excellent) polyamide to alicyclic to aliphatic aromatic (good)

Acid resistance: (excellent) aromatic to alicyclic to aliphatic to polyamide (inferior)

Water resistance: (excellent) polyamide to aliphatic amine to alicyclic amine to aromatic amine (good) {page_break}

　 Chemical structure of polyamine curing agents and properties of cured resin with bisphenol A resin

For gloss, aromatic is the best and aliphatic is the worst. This property is affected by curing temperature, and the luster becomes better with the increase of temperature. As for softness, polyamide with long distance between functional groups is better, while aromatic amine with high crosslinking density is poor. Heat resistance is just the opposite of softness, while adhesion is consistent with softness. The drug resistance (acid tolerance) is affected by chemical structure. Aromatic compounds are excellent, and fatty amine and polyamide are easily corroded by chemicals. Water resistance is controlled by the mass concentration of functional groups, and the polyamides with low mass concentration and high hydrophobicity are more resistant to water, while the aromatic group with high functional group concentration is worse.

　 Application and Application

Curing agent purpose It can be divided into normal temperature curing agent and heating curing agent. Epoxy resin curing at high temperature is generally good in performance, but the coatings and adhesives used in civil buildings need to be cured at room temperature because of the difficulty of heating. Most of them use aliphatic amine, aliphatic ring and polyamide, especially the coatings and adhesives used in winter to be used with polyisocyanates or using polyphor alcohols with odorous odor.

As for medium temperature curing agents and high temperature curing agents, they should be selected on the basis of heat resistance and heat resistance, adhesion and drug resistance of cured products. The selection focuses on Polyamine and anhydride. Because of their excellent electrical properties, the anhydride cured compounds are widely used in electronics and electrical appliances.

Aliphatic polyamine cured products are excellent in adhesion, alkali resistance and water resistance. Aromatic polyamines are also excellent in drug resistance. Due to the formation of hydrogen bonds between the nitrogen elements of the amino group and the metal, it has excellent antirust effect. The higher the mass concentration of amine, the better the antirust effect. The anhydride curing agent and epoxy resin form ester bonds, showing high resistance to organic acids and inorganic acids, and their electrical properties generally exceed that of polyamines.