Method for rapidly detecting free toluene diisocynate in polyurethane coating

Abstract

The invention discloses a method for rapidly detecting free toluene diisocynate in a polyurethane coating. The detection method is carried out by adopting gas chromatography under specific test conditions, and comprises the steps of 1) saturating a chromatographic column and quartz wool in a liner tube by adopting a toluene diisocyanate solution with the mass concentration of 2.5-3.5% so as to enable the chromatographic column and the quartz wool to reach an analysis state; 2) respectively carrying out gas chromatographic analysis on a first calibration solution and a second calibration solution to obtain two different correction factors, wherein the contents of toluene diisocynate in the first calibration solution and the second calibration solution are different; and 3) carrying out gaschromatographic analysis on the sample solution, and calculating according to a formula. The method provided by the invention has the advantages of convenience, rapidness, low detection cost, high accuracy and short test time, and has the capability of accurately carrying out batch analysis.

Description

technical field [0001] The invention belongs to the technical field of chromatographic analysis, and in particular relates to a rapid detection method for free toluene diisocyanate in polyurethane coatings. Background technique [0002] As one of the fastest-growing and most widely used varieties in the coatings industry, polyurethane coatings have excellent comprehensive properties such as various types, good decoration, high gloss, water resistance and corrosion resistance. , The requirements for decoration and decoration are constantly improving, and the application of polyurethane coatings in new building materials, furniture, decoration materials, waterproof and plugging and other fields is becoming more and more extensive and proficient. Toluene diisocyanate (TDI) is one of the main raw materials of polyurethane coatings. Although it can obviously improve the performance of polyurethane coatings, it also endangers the health of people who come into contact with it. Ma...

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Problems solved by technology

Due to the low concentration of the calibration solution in the standard, it often takes several hours when the column fixative and the quartz wool in the liner are saturated.

Moreover, the TDI monomer is very active, and it is very easy to absorb trace moisture that cannot be removed in the air or even in the solvent to react. It is found that even if the TDI calibration solution is sealed and stored in a low-temperature refrigerator, as the storage time increases, the concentration of TDI in the gas chromatography will decrease. There will also be a reduction in peak area, resulting in a lower correction factor, which in turn leads to higher detection results

[0005] In addition, the inventors of the present invention have found that the thermal instability of TDI, the integral uncertainty brought by gas chromatographic peak tailing, the incomplete separation of internal standard and TDI, the adsorption of TDI by quartz wool in chromatographic column stationary liquid and liner Sex, etc., will have a certain impact on the test results

Moreover, in order to ensure the utilization rate and detection efficiency of the instrument, the third-party testing institutions almost all adopt the mode of batch analysis, so that the samples to be tested need different degrees of waiting time from the preparation to the completion of the analysis, which affects the test results; and for small-scale As far as testing institutions are concerned, due to limited equipment and capabilities, often a gas chromatograph needs to cross-test multiple substances, and it is even more difficult to ensure the timeliness and accuracy of testing data

Moreover, with the continuous improvement of technology, the content of free TDI in most polyurethane coatings is getting lower and lower, and the deviation of test results will also become larger and larger.

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