News Details
Acid anhydride coating crosslinking agent
2017-8-30 12:07:23
Acid anhydride coating crosslinking agent
In principle all low molecular weight anhydride such as phthalic anhydride, maleic anhydride and benzoic anhydride can be used for crosslinking epoxy resin or epoxy - based resin.
The typical products of acid anhydride crosslinking agent are: phthalic anhydride, phthalic anhydride and the modified acid anhydride. The molecular structure of anhydride crosslinking agent contains anhydride base.
The basic characteristics of anhydride crosslinking agent are:
(1) the crosslinking speed is slower, the crosslinking heat is smaller, and the cross-linking shrinkage rate is small.
(2) high thermal deformation temperature of crosslinked products, good anti-chemical, anti-ultraviolet and heat-resistant properties;
(3) excellent mechanical and electrical performance;
(4) low melting viscosity can add more packing. For powder coatings containing epoxy or hydroxypolyester as resin, acid anhydride can be used as crosslinking agent.
In terms of epoxy resin, containing only one anhydride ring anhydride can make its infinite network, because after the anhydride ring by ring-opening esterification, formed by carboxyl can react with the resin epoxy group. For the resin containing hydroxy functional groups, only binary or polyanhydride is the appropriate crosslinking agent.
Since the acid anhydride base does not contain active H atoms, it cannot react directly with the epoxy base, and it must be added to the crosslinking promoter to open the acid anhydride ring. The commonly used stimulants are tertiary amine, tertiary amine salt, mimidazolite and season salt.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
In principle all low molecular weight anhydride such as phthalic anhydride, maleic anhydride and benzoic anhydride can be used for crosslinking epoxy resin or epoxy - based resin.
The typical products of acid anhydride crosslinking agent are: phthalic anhydride, phthalic anhydride and the modified acid anhydride. The molecular structure of anhydride crosslinking agent contains anhydride base.
The basic characteristics of anhydride crosslinking agent are:
(1) the crosslinking speed is slower, the crosslinking heat is smaller, and the cross-linking shrinkage rate is small.
(2) high thermal deformation temperature of crosslinked products, good anti-chemical, anti-ultraviolet and heat-resistant properties;
(3) excellent mechanical and electrical performance;
(4) low melting viscosity can add more packing. For powder coatings containing epoxy or hydroxypolyester as resin, acid anhydride can be used as crosslinking agent.
In terms of epoxy resin, containing only one anhydride ring anhydride can make its infinite network, because after the anhydride ring by ring-opening esterification, formed by carboxyl can react with the resin epoxy group. For the resin containing hydroxy functional groups, only binary or polyanhydride is the appropriate crosslinking agent.
Since the acid anhydride base does not contain active H atoms, it cannot react directly with the epoxy base, and it must be added to the crosslinking promoter to open the acid anhydride ring. The commonly used stimulants are tertiary amine, tertiary amine salt, mimidazolite and season salt.
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
Main disadvantages:
(1) high moisture absorption. Anhydride and easy to absorb moisture in the air and the reaction generates free acid, with epoxy resin reaction time won't get enough of the crosslinking density, hinder crosslinking effect, crosslinking the electric properties of things will be dramatically reduced. Therefore, as far as possible in storage and application, try to avoid the air contact, avoid the high temperature environment, and the packaging should be sealed as far as possible.
(2) when the heat is heated, the reaction of CO2 will be produced, and it is easy to form a pinhole inside the crosslink.
(3) there is a strong stimulation to the respiratory tract during construction. Although the use of acid anhydride as a crosslinking agent for powder coatings can be solved, there are still insurmountable obstacles to the wide acceptance of these systems in view of toxicity.
Acid anhydride is an oxygen-containing acid that removes a molecule of water or a few molecules of water, the rest of it. The common inorganic acid is the acid of a molecule, which directly loses the water of a molecule to form the acid anhydride of the acid, and its acid anhydride determines the valence of the acidic element. The organic acids are the two molecules of the acid or polymolecule that are formed by the reaction of the molecules. Only oxygenated acid is the only acid anhydride. Anaerobic acid is not anhydride.
Acid anhydride is generally considered to be an oxide of acid dehydration. Many can rehydrate with water to become the original acid. According to the properties of acids, it can be divided into: (1) the anhydride of inorganic acid, which is reduced by one or two acids. For example, carbon (acid) anhydride (acid) is carbon dioxide (CO2), nitric acid (acid) anhydride (acid) and nitric oxide (N2O5). (2) acid anhydride of organic acids, compounds that are reduced by two mono-acid molecules or a divalent molecule, though not oxides, also known as anhydride. For example, b (acid) anhydride (CH3CO) 2O, phthalic anhydride C8H4O3, etc.
"Acid anhydride is acid oxide" is true in a certain range. Acid anhydride is formed by acid dehydration, while acid oxide reacts with alkali to form the salt and water oxides. Conceptually, they are not equivalent. Anhydride in inorganic chemistry is the formation of acid dehydration, and the vast majority of oxide, so they can be equal, but in organic chemistry, many organic acids are not oxide after dehydration, such as acetic acid (CH3COOH), dehydrated to form acetic anhydride ((C4H6O3, (CH3CO) 2 o), so it can't be acidic oxides.
Main disadvantages:
(1) high moisture absorption. Anhydride and easy to absorb moisture in the air and the reaction generates free acid, with epoxy resin reaction time won't get enough of the crosslinking density, hinder crosslinking effect, crosslinking the electric properties of things will be dramatically reduced. Therefore, as far as possible in storage and application, try to avoid the air contact, avoid the high temperature environment, and the packaging should be sealed as far as possible.
(2) when the heat is heated, the reaction of CO2 will be produced, and it is easy to form a pinhole inside the crosslink.
(3) there is a strong stimulation to the respiratory tract during construction. Although the use of acid anhydride as a crosslinking agent for powder coatings can be solved, there are still insurmountable obstacles to the wide acceptance of these systems in view of toxicity.
Acid anhydride is an oxygen-containing acid that removes a molecule of water or a few molecules of water, the rest of it. The common inorganic acid is the acid of a molecule, which directly loses the water of a molecule to form the acid anhydride of the acid, and its acid anhydride determines the valence of the acidic element. The organic acids are the two molecules of the acid or polymolecule that are formed by the reaction of the molecules. Only oxygenated acid is the only acid anhydride. Anaerobic acid is not anhydride.
Acid anhydride is generally considered to be an oxide of acid dehydration. Many can rehydrate with water to become the original acid. According to the properties of acids, it can be divided into: (1) the anhydride of inorganic acid, which is reduced by one or two acids. For example, carbon (acid) anhydride (acid) is carbon dioxide (CO2), nitric acid (acid) anhydride (acid) and nitric oxide (N2O5). (2) acid anhydride of organic acids, compounds that are reduced by two mono-acid molecules or a divalent molecule, though not oxides, also known as anhydride. For example, b (acid) anhydride (CH3CO) 2O, phthalic anhydride C8H4O3, etc.
"Acid anhydride is acid oxide" is true in a certain range. Acid anhydride is formed by acid dehydration, while acid oxide reacts with alkali to form the salt and water oxides. Conceptually, they are not equivalent. Anhydride in inorganic chemistry is the formation of acid dehydration, and the vast majority of oxide, so they can be equal, but in organic chemistry, many organic acids are not oxide after dehydration, such as acetic acid (CH3COOH), dehydrated to form acetic anhydride ((C4H6O3, (CH3CO) 2 o), so it can't be acidic oxides.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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