News Details
Epoxy resin polyamine coating crosslinking agent
2017-7-21 11:10:56
Epoxy resin polyamine coating crosslinking agent is the epoxy resin cross-linking agent in the most varieties, mainly divided into four categories: single polyamine, including aliphatic polyamines, polyamide polyamines, alicyclic polyamines , Aromatic polyamines and other varieties; mixed polyamines; modified polyamines, including epoxy compound addition polyamines, Michael addition polyamines, Mannese addition polyamines, ketone-blocked polyamines; eutectic mixing Polyamines.
Epoxy resin polyamine cross-linking agent, also known as addition polymerization type two. Epoxy resin polyamine cross-linking agent cross-linking reaction mechanism is: polyamine cross-linking agent in the reaction with epoxy resin, the first primary amine active hydrogen and epoxy reaction, the formation of secondary amine; secondary amine The active hydrogen reacts with the epoxy group to produce a tertiary amine, which is carried out in two steps.
The first step - the tertiary amino group produced in the reaction, has a catalytic function, but in the presence of primary amine, secondary amine conditions, its function is generally difficult to play. (Note: In practice, there will be some people think that the addition of active hydrogen and tertiary amine catalysis at the same time the existence of the situation.
In the case of cross-linking bisphenol A epoxy resin with diethylaminopropylamine, when only 75% of diethylaminopropylamine is measured in terms of the amount of active hydrogen and epoxy groups, the epoxy groups in the system consume 95 %; And if 1,6-hexanediamine as a cross-linking agent, the active hydrogen and epoxy groups and other substances measured in hexamethylene diamine only 50% consumption, the system of epoxy groups have consumed 95 %.
In this case. It is explained that the addition process releases a large amount of heat, accompanied by the formation of hydroxyl groups, so that the tertiary amine on the cross-linking reaction produced a catalytic effect. ) The crosslinking reaction of the above polyamine requires two points to be described. First, because of the chemical structure and alkaline differences are quite different.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
Epoxy resin polyamine cross-linking agent, also known as addition polymerization type two. Epoxy resin polyamine cross-linking agent cross-linking reaction mechanism is: polyamine cross-linking agent in the reaction with epoxy resin, the first primary amine active hydrogen and epoxy reaction, the formation of secondary amine; secondary amine The active hydrogen reacts with the epoxy group to produce a tertiary amine, which is carried out in two steps.
The first step - the tertiary amino group produced in the reaction, has a catalytic function, but in the presence of primary amine, secondary amine conditions, its function is generally difficult to play. (Note: In practice, there will be some people think that the addition of active hydrogen and tertiary amine catalysis at the same time the existence of the situation.
In the case of cross-linking bisphenol A epoxy resin with diethylaminopropylamine, when only 75% of diethylaminopropylamine is measured in terms of the amount of active hydrogen and epoxy groups, the epoxy groups in the system consume 95 %; And if 1,6-hexanediamine as a cross-linking agent, the active hydrogen and epoxy groups and other substances measured in hexamethylene diamine only 50% consumption, the system of epoxy groups have consumed 95 %.
In this case. It is explained that the addition process releases a large amount of heat, accompanied by the formation of hydroxyl groups, so that the tertiary amine on the cross-linking reaction produced a catalytic effect. ) The crosslinking reaction of the above polyamine requires two points to be described. First, because of the chemical structure and alkaline differences are quite different.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
A reagent grade additives
For aliphatic amines, k1 / k2? 2, in the case where the primary amine is preferentially reacted, the chain growth reaction is carried out in parallel with the secondary amine cross-linking reaction. For the aromatic amine, k1 / k2 ≌ 7 ~ 12, based on the reaction of the primary amine chain growth reaction overwhelming advantage.
Therefore, the B-stage of the reaction between the epoxy resin and the aliphatic primary amine is very short, difficult to control, and there is a longer B-stage time in the aromatic amine. The length of this B-stage is very important, using this feature can be made into B-stage molding materials, such as powder coatings.
The second step - Lewis acid can promote the role of this reaction, which promote the role of acid by the PKa domination, the order: acid> phenol> alcohol> nitrile> nitrobenzene. In formulations where the aromatic amine cross-linker is used, it is sometimes necessary to add a promoter to shorten the gel time, but the addition of the accelerator will adversely affect the properties of the crosslinker.
For some amine and epoxy reaction, the addition of appropriate amount of water or alcohol compounds (containing hydroxyl groups), can accelerate its reaction. In the case of phenyl glycidyl ether, the order of acceleration of the alcohols is: methanol> ethanol> n-propanol> t-butanol> isobutanol> cyclohexanol. The hydroxyl groups in the molecular structure of the amine cross-linking agent also have an accelerating effect on the crosslinking reaction.
Such as bisphenol A epoxy resin gel time sequence: diethylene diamine, hydroxyethyl diethylenetriamine> dihydroxyethyl diethylenetriamine, different organic acids on the amine cross-linking agent and epoxy resin The reaction also has an impact. In the order of reaction of bisphenol A epoxy resin with amine, the order of reaction rate of adding different acids is: p-toluenesulfonic acid> salicylic acid> formic acid> benzoic acid> lactic acid> oxalic acid> acetic acid> n-butyric acid> Diacids> phthalic acid.
The effect of the addition of the substance on the reaction rate in the epoxy-amine crosslinking reaction can be attributed to whether they contribute to the generation of hydrogen bonds because the formation of hydrogen bonds accelerates the reaction between amine and epoxy groups.
Thermal Effect of Crosslinking Epoxy Resin with Polyamine Crosslinker. The reaction between amine crosslinking agent and epoxy group is exothermic reaction, and epoxy resin cross-linked molding material is mostly insulating material, so it is very important to study the thermal effect of resin crosslinking.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
For aliphatic amines, k1 / k2? 2, in the case where the primary amine is preferentially reacted, the chain growth reaction is carried out in parallel with the secondary amine cross-linking reaction. For the aromatic amine, k1 / k2 ≌ 7 ~ 12, based on the reaction of the primary amine chain growth reaction overwhelming advantage.
Therefore, the B-stage of the reaction between the epoxy resin and the aliphatic primary amine is very short, difficult to control, and there is a longer B-stage time in the aromatic amine. The length of this B-stage is very important, using this feature can be made into B-stage molding materials, such as powder coatings.
The second step - Lewis acid can promote the role of this reaction, which promote the role of acid by the PKa domination, the order: acid> phenol> alcohol> nitrile> nitrobenzene. In formulations where the aromatic amine cross-linker is used, it is sometimes necessary to add a promoter to shorten the gel time, but the addition of the accelerator will adversely affect the properties of the crosslinker.
For some amine and epoxy reaction, the addition of appropriate amount of water or alcohol compounds (containing hydroxyl groups), can accelerate its reaction. In the case of phenyl glycidyl ether, the order of acceleration of the alcohols is: methanol> ethanol> n-propanol> t-butanol> isobutanol> cyclohexanol. The hydroxyl groups in the molecular structure of the amine cross-linking agent also have an accelerating effect on the crosslinking reaction.
Such as bisphenol A epoxy resin gel time sequence: diethylene diamine, hydroxyethyl diethylenetriamine> dihydroxyethyl diethylenetriamine, different organic acids on the amine cross-linking agent and epoxy resin The reaction also has an impact. In the order of reaction of bisphenol A epoxy resin with amine, the order of reaction rate of adding different acids is: p-toluenesulfonic acid> salicylic acid> formic acid> benzoic acid> lactic acid> oxalic acid> acetic acid> n-butyric acid> Diacids> phthalic acid.
The effect of the addition of the substance on the reaction rate in the epoxy-amine crosslinking reaction can be attributed to whether they contribute to the generation of hydrogen bonds because the formation of hydrogen bonds accelerates the reaction between amine and epoxy groups.
Thermal Effect of Crosslinking Epoxy Resin with Polyamine Crosslinker. The reaction between amine crosslinking agent and epoxy group is exothermic reaction, and epoxy resin cross-linked molding material is mostly insulating material, so it is very important to study the thermal effect of resin crosslinking.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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