Anhydride coating crosslinking agent

Anhydride coating crosslinking agent, in principle all the low molecular weight anhydride, such as phthalic anhydride, maleic anhydride and benzene partial three anhydride can be used for crosslinked epoxy resin or epoxy resin.

Typical products are:, all four benzene anhydride and trimellitic anhydride modified new anhydride. Anhydride class is contained in the molecular structure of the crosslinking agent anhydride base. Basic features are:

(1) crosslinking slower, less crosslinking exothermic, crosslinking little shrinkage.

(2) high thermal deformation temperature of crosslinking, chemical resistance, uv resistance and resistance to hot and humid performance good;

(3) mechanics and excellent;

(4) components low melt viscosity, can add more packing. For containing epoxy resin or hydroxyl polyester as resin powder coatings can choose anhydride as cross-linking 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 hydroxyl groups, only 2 yuan or multiple anhydride is suitable crosslinking agent.

Because anhydride base contains no active H atoms, the epoxy groups and cannot be directly reaction, must add crosslinking promoter to open anhydride ring. Commonly used promoters have tertiary amine and tertiary amine salt, imidazoles, quaternary salts.




Chinese name: Diethyl toluene diamine(DETDA)

Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.

Density 1.022

Viscosity (20 ℃) ??mPa·ss290±10

Pour Point ℃-9

Boiling point of310°C

Flash Point°C161.1°C


Major faults:

(1) the hygroscopicity is bigger. 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. So when used in storage and control and air contact less as far as possible, as far as possible to avoid the high temperature environment, will try to seal packing.

When heated, (2) produces CO2 response, easy to make crosslinking internal form a pinhole.

(3) construction of respiratory tract has strong stimulation. Although using anhydride as powder coating crosslinking agent concerned technical problems can be solved, but considering the toxicity, make the market widely accepted these system still exist insurmountable obstacles.

Anhydride is a oxyacid off a molecule of water or a few molecules of water, the rest part. General inorganic acid is a member of the acid, lose a molecule of water is directly form the acid anhydride, its decide acid anhydride the combining power of the elements of the same. And organic acid is more than two molecules of the acid or molecules of the acid by intermolecular dehydration reaction. Only oxygen acid anhydride. There is no anhydride of anaerobic acid.

Acid anhydride is considered to be a general by dehydration of oxide (organic acid anhydride do not belong to the oxide). Many can function as the original acid with water. According to the nature of the acid can be divided into: (1) the inorganic acid anhydride, shrink by one or two acid molecules.

Such as carbon (acid) anhydride is carbon dioxide, CO2 (acid) anhydride nitrate nitrogen N2O5 pentoxide. (2) organic acid anhydride, made up of two unary acid molecules or shrink and become a dibasic acid molecules compounds, is not oxide, also known as acid anhydride. Such as b (acid) anhydride (CH3CO) 2 o, C8H4O3 phthalic anhydride, etc.

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Diethyl toluene diamine(DETDA)  http://www.yaruichem.com