The coating USES low temperature crosslinking agent performance test

The coating USES low temperature crosslinking agent performance test: the experimental part

The performance of the crosslinking agent for the low temperature used in several markets was determined. In this study, a phenyl alkylamine cross-linking agent was used as a control, because its low temperature performance was familiar to everyone in the industry. Crosslinking agent 1 is a modified amine addition that is used at low temperature.

The crosslinking agent 2 is an amine addition, which is provided by a n-butanol/dimethylbenzene solution of 60% wt solid. Low temperature epoxy coatings are quick and excellent solvents when used for crosslinking. Crosslinking agent 3 is a non-phenolic modified mannichbase, which can be used for rapid crosslinking of low temperature crosslinking coatings. The physical properties of these crosslinking agents are shown in table 1.

The first part of the study was to evaluate the performance of the bi-functional liquid epoxy resin (WPE = 198, appendix 1) of these crosslinking criteria. Each paint mixture is mixed and mixed with a mixture of solvents (methyl isobutyl/xylene/butanol = 1:1:1) to the GardnerH viscosity. The varnish is mixed with 5min and then applied to the glass plate with a scratch plate (the dry film is 1.5 mil, the wet film 63 mu), and the coating is immediately put into the constant temperature and humidity box.

Periodic measurement of the transparency, viscosity and pencil hardness of the coating was determined by a period (two weeks). Each have system adopts three different crosslinking conditions: 25 ℃, relative humidity (RH) 55%; 10 ℃, RH90 %, and 4.5 ℃, RH80 %. The test results are summarized in table 2.

In addition to measuring the performance of the varnish film, we also tested the crosslinking rate of the paint base system with the differential scanning heat meter (DSC). The measurement consists of three steps. The first step is to use the DSC/TGA (heat reanalysis) to determine the range of temperature scans of the mixed group (non-solvents). The results showed that the temperature range was determined by the heat transfer, and at the temperature limit, the weightloss was negligible (ie, less than 1% weight).

Using the DSC/TGA (from 50 to 170 f) to determine the temperature after the scan range, at a constant heating rate (10 ℃ / min) for the DSC scan, total heat of reaction of each have been system (delta H total) were determined. After reaching maximum temperature, quenching to sample - 50 ℃, to heating measurement to see if there are after cross-linking phenomena appear. In all cases, no post-crosslinked phenomena were found when each DSC scan was found.




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


Testing the last step is to mix a new good sample loading in the DSC vessels and immediately frozen samples to - 130 ℃ (dry ice); System resources to seven samples at the same time, the preparation of the seven samples of total time is less than 5 min, the seal of the DSC storage vessels in 4.5 ℃ freezer to scheduled days.

To the provisions of the number of days, a sealed samples out of the freezer and immediately under 0 ℃ / min constant heating rate measured by DSC scan. Click here to get seven data, draw a curve, integral DSC scan line at the bottom of the area, it is concluded that have been system under 4.5 ℃ after X days crosslinking of residual heat of reaction (delta H  left), using the following equation (1) to calculate the reaction degree of each sample (or crosslinking %) :

Reaction degree, % = (1 - [delta H /  left delta H  total] (100) (1)

We found that when in the standard room temperature (25 ℃, RH55 %), each kind of crosslinking agent mixed income of coating with liquid epoxy resin are relatively fast drying time and gel time. It has the greatest activity because of the shortest gelatinization time and Gardner drying time.

Crosslinking agent 2 looks the longest, because it contains the solvent and makes the Shyodu gel longer. In the absence of solvents, the cross-linking agent 2 is a solid resin, so the measurement of its gelatinization time cannot be performed honestly. Crosslinking agent 2 and liquid epoxy resin blended Gardner, fast drying time is the second, but the speed may contain some false from the amine adduct solution volatile paint dry.

Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd 

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