| Cars have been used widely by people more and more.However,it is a relatively closed space,as the glue and sealant used in the process of car production,although the content of the harmful substance is low,some harmful substances will gradually release after construction,such as formaldehyde,benzene,halogenated hydrocarbon,etc.Some polyurethane adhesive will still remain in residual such as toxic diisocyanate monomer after construction.Long-term exposure to these harmful substance may cause serious harm to human health.At present,limited content of harmful substances in adhesive for shoes,bags and indoor decoration was mainly described in the detection standards such as GB 19340-2003 and GB 18583-2008.However,there is a lack of corresponding detection and evaluation methods for the emission of hazardous substances in adhesive for automobile.Therefore,in this paper,the subject of diisocyanate compounds has been focused.The method used for determination of harmful substances in polyurethane adhesive for automobile has been established as well as the rule of emission has been studied.The research achievements would have some theoretical guidance for the risk assessment after the adhesive constructed in cars.Five main research contents are included in this paper shown as follows.1.Two diisocyanate compounds in automotive polyurethane adhesives were detected simultaneously by the method of high performance liquid chromatography(HPLC)withderivative before the column.Non-volatile isocyanate urea derivatives were formed by the reaction of sample and 1-(2-methoxyphenyl)piperazine(1-2MP)as reagents in the toluene(toluene is retreated by molecular sieves of 4A grade to dehydrate).And then the derivatives were desorbed with acetic anhydride and analysed by HPLC.The detection limits of two diisocyanate derivatives(2,6-TDI-1-2MP and HDI-1-2MP)were 0.17?g/m3 and 0.33?g/m3 respectively.The linearity range was between 0.01 and 20.00 mg/L with the correlation coefficients were 0.9964-0.9999.Theaverage recoveries of standard addition were 81.3%~98.7% and 80.3%~98.2% respectively with the relative standard deviation(RSD,n=3)of 1.95%~5.16% and 2.00%~6.10% respectively.It is certified that this method exhibited the advantages of simple pretreatment,high sensitivity,low detection limit and good stability.This method will provide a theoretical basis for the establishment of evaluation standard of diisocyanate compounds in the future.2.With relative humidity of environment factors as the research object,at the condition of different relative humidity 30%,50%,70% of the small emission test chamber,the emission of2,6-TDI was studied with the change of time.The attenuation equation and half life at different relative humidity are y=696.018e-0.0505x+13.362,34.00h(30%);y=503.281e-0.0563x+11.628,30.62h(50%);y=365.186e-0.0629x+9.822,22.21h(70%).It turned out that the concentration of2,6-TDI in the small emission test chamber decreased when the relative humidity increased as well as the emission rate of 2,6-TDI decayed quickly.Therefore construction in the rainy season is advantageous to the release of 2,6-TDI in polyurethane adhesive inside cars.3.With temperature of environment factors as the research object,at the condition of different temperature 18°C,23°C,35°C of the small emission test chamber,the emission of2,6-TDI was studied with the change of time.The attenuation equation and half life at different temperatures are y=461.666e-0.0545x+10.451,33.63h(18°C);y=503.281e-0.0563x+11.628,30.62h(23°C);y=906.231e-0.0793x+15.458,19.88h(35°C).It turned out that the concentration of2,6-TDI in the small emission test chamber increased when the temperature increased as well as the emission rate of 2,6-TDI decayed quickly.Therefore construction in the summer is advantageous to the release of 2,6-TDI in polyurethane adhesive inside cars.4.With air exchange rates of environment factors as the research object,at the condition of different air exchange rates 3.3L/min,8.3L/min,13.3L/min of the small emission test chamber,the emission of 2,6-TDI was studied with the change of time.The attenuation equation and half life at different air exchange rates are y=861.365e-0.0420x+5.779,44.48h(3.3L/min);y=503.281e-0.0563x+11.628,30.62h(8.3L/min);y=412.388e-0.0701x+3.971,15.03h(13.3L/min).It turned out that the concentration of 2,6-TDI in the small emission test chamber decreased when the air exchange rates increased as well as the emission rate of 2,6-TDI decayed quickly.Therefore ventilation after construction is advantageous to the release of 2,6-TDI in polyurethane adhesive inside cars.5.After the study on the emission experiment model of 2,6-TDI releasing from automotive polyurethane adhesive,it was found that the emission of 2,6-TDI basically corresponded to VB model and POWER principle. |
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