Pure polyester powder coatings crosslinking agent

Pure polyester powder coatings crosslinking agent,Pure polyester powder coating is developed after epoxy, epoxy/polyester thermoset, weatherability, powder coatings, powder coatings with mostly saturated polyester resin type, we usually according to its basic structure can be divided into two categories, end carboxyl and end hydroxyl groups.

End carboxyl polyester the number average molecular weight between 2000-8000, acid value, from 20-100 mgKOH/g. Among them, the medium and high acid value (45-85) is commonly used in epoxy/polyester blended powder coating, in the low acid value (20-45) with three different melamine urea acid polyester glycidyl ester (TGIC), hydroxy amide as crosslinking agent preparation weatherability excellence of pure polyester powder coating.

Initial attempt is made of pure polyester powder coating time, in the late 1960 s, in the patent of HoechstAG, respectively containing carboxyl and containing hydroxyl groups of the two kinds of polyester smash, physical mixing powder coating, in 220 ℃ crosslinking for 15 minutes. An example of this patent is to put the two kinds of polyester melt mixing with titanium pigment, cooling after crushing, the system obtained at 220 ℃ crosslinking for 15 minutes.

Powder coating with thermosetting polyester resin is a big advantage can adjust functionality, make on the polymer chains in the position of the need of the crosslinked coating performance will have a significant impact. This is why the polyester resin and acrylic resin has better mechanical properties than for one reason, such as the latter is random distribution of functional groups.
Polyester resin can be used to produce solvent coating polyester or high molecular weight polyester production the same device. In the production of high molecular weight polyester resin flow to cooling, equipped with a rotating crusher was finally broken into the appropriate size of the resin (such as 1 mm * 2 mm).

In the design of polyester powder coatings with good weatherability, correct selection of crosslinking agent is very important. Crosslinking agent at the same time should also be resistant to ultraviolet radiation, only a handful of crosslinking agent is solid at room temperature, different cyanuric acid three glycidyl ester (TGIC) has been used for years in Europe since 1998, has been increasingly replaced by the crosslinking agent of the low-toxic and non-toxic.

By topical type TGIC powder coating more than 25 years of experience in production and application, have confirmed the reliability of the system can provide long-term protection. It was not until 2000 that polyester/TGIC system still dominates the powder coating for external use.

TGIC powder coating in the dosage depends on the acid value of the polyester resin. When TGIC is contained in the chemical calculation of epoxy group and polyester carboxyl equal, you can get the best effect. The following formula can be used for the calculation of TGIC stoichiometric value, acid value of polyester resin known:




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


TGIC = R * AV * 107/56100

TGIC = the amount of TGIC (g)

R = the dosage of the polyester resin (g)

AV = polyester resin acid value (mg KOH/g)

For polyester/TGIC system The general terms of crosslinking is 200 ℃ / 10 minutes, generally without catalyst, because TGIC is reactive enough to get by crosslinking cycle of hope.

Also introduced some of the other in the market of the crosslinking agent products, used as the substitute of TGIC, beta hydroxy alkyl amide, is the most important class of goods is called "Primid", carboxyl polyester and beta hydroxy alkyl amide (HAA) is not of the crosslinking reaction between addition polymerization (such as the crosslinking reaction of TGIC), but the condensation polymerization reaction.

This means that the water release in the baking process. Also, since there are amino to "Primid" as the base of the powder coating transition baking yellowing resistance (mainly refers to the situation with direct-fired gas stove) TGIC is better than good.

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