Research on the Emission Test of Automotive Interior Coatings

The air quality problem in the car is closely related to people's physical and mental health, so it has been paid more and more attention. The air pollution in the car is mainly caused by the volatile organic compounds (VOCs) volatilized from the interior parts of the car (paint, plastic, rubber, leather, carpet and other decorative materials) when heated. Therefore, the effective establishment of the determination method for the organic volatiles of automotive interior parts and related materials and the control of the emission of organic matter from the pollution source are the key to solving the air pollution in the car. This is of great significance for advocating the concept of environmentally friendly consumption and promoting the healthy and sustainable development of the automotive industry. It is understood that there is no relevant national standard method for testing the volatile organic compounds of automotive interior parts or decorations. At present, the detection of volatile organic compounds in automotive interior parts and materials generally uses thermal desorption-gas chromatography mass spectrometry (TDS-GC/MS), headspace-gas chromatography (HS-GC), sampling bag-thermal desorption Attached is a gas chromatography mass spectrometry (Bag-TDS-C, C/MS) and high performance liquid chromatography (HPLC). The author of this article aims to establish a simple and feasible method for the determination of volatile organic compounds in automotive interior materials by using the environmental test box developed by our institute, that is, the test box-thermal desorption-gas chromatography method. This method uses total carbon ( Using toluene as the equivalent) to characterize the volatile amount of volatile organic compounds, it replaces the quantitative method of Bag-TDS-GC/MS to a certain extent, and can effectively evaluate the volatility of materials. In addition, this method was used to determine the emission of volatile organic compounds in five automotive interior coatings. 1. Test part 1.1 Test principle Put the dried coating sample in a closed environment test box, and after a certain time of emission test under certain temperature and humidity conditions, use Tenax TA adsorption tube to quantitatively collect the emitted sample Volatile organic compounds. After sampling, connect the adsorption tube to the gas chromatography system for analysis and testing. The component to be tested enters the gas chromatographic column with the inert carrier gas and is detected by FID, qualitatively determined by retention time, and quantified by peak area. Using n-eicosane (C20) as the marker and toluene as the equivalent, calculate all the boiling points lower than C20. The sum of substances, characterized by the total carbon content, is the amount of volatile organic compounds emitted from the sample, and the emission is used to study its emission. 1.2 Test instrument and material KFlll-02UB environmental test chamber: self-developed by Guangzhou Institute of Synthetic Materials, sealed volume 0.24m3, sampling inlet and outlet of circulating air flow, available for sampling connection; temperature and humidity test conditions can be controlled and adjusted by program ; Can provide test light source. QC-2 Air Sampler: Beijing Labor Protection Research Institute. GC7890 II gas chromatograph: Shanghai Tianmei Chromatography Instrument Co., Ltd. rip-2030 thermal desorption instrument: Beijing Beifen Tianpu Instrument Company. Tenax-TA adsorption tube: Beijing Zhongke Huijie Analytical Technology Co., Ltd. Three sets of automotive interior coating samples (1’, 2+, 3.): Guangdong Yatu Chemical Co., Ltd. Methanol: analytically pure. Toluene: above analytical grade. Eicosane: analytically pure. 1.3 Preparation of coating samples Prepare mixed samples according to the construction ratio of the product. After stirring, spray or paint on clean aluminum foil with a size of 210mm×148mm, and control the dry film thickness to 501xm+5 1xm. Then, the coated sample was dried according to the drying conditions provided by the product supplier, and ventilated at room temperature for 24 hours after drying, and then wrapped in aluminum foil and placed in a polyethylene bag to be sealed for testing. 1.4 Test conditions p. J1.4.1 Gas chromatography conditions Chromatographic column: polydimethylsiloxane capillary column, 50m×0.32mm×1. O bucket m; the column temperature adopts a program to increase: the initial temperature is 50 ℃ for 5 minutes, and then the rate is 8. C/min increased to 260cc and kept for 10min; temperature of injection port: 280℃; temperature of detector: 280℃; flow rate of carrier gas: 2.0ml/min; split ratio: 15:1. 1.4.2 Thermal desorption conditions Desorption temperature: 280℃; desorption time: 5 min; sampling time: 50s; desorption gas flow rate: 50ml/min. 1.5 Test procedure 1.5.1 Determination of the response coefficient of toluene Take 2 liters of this solution and quickly inject the sample into the adsorption tube, and pass the nitrogen flow to make the standard sample fully absorbed. Then, connect a gas chromatograph for thermal desorption analysis, record the chromatogram and peak area, and calculate the response coefficient of toluene. 1.5.2 Coating emission test According to the specified load rate, weigh a coating sample of a certain quality and place it in an environmental test box with set test conditions for a certain period of emission test. 1.5.3 Sampling and analysis Sampling conditions: flow 200-500mL/min, time 20-50min, general sampling volume is 10L.