Research status of domestic automotive interior materials VOC detection technology

In recent years, automobiles have become an indispensable part of people's daily life, but the air pollution in the car seriously threatens human health, and the main factor causing the air pollution in the car is the volatilization of harmful gases in the interior materials of the car

In recent years, with the continuous improvement of living standards, people's awareness of environmental protection has become stronger and stronger, so more and more attention has been paid to the air quality in the car

01 Status quo of relevant standards for VOC testing of automotive interior materials in my country

At this stage, the only national standards promulgated in China for in-vehicle air quality issues are GB/T 27630-2011 "Guidelines for Air Quality Evaluation in Passenger Cars"[2] and HJ/T400 "In-vehicle volatile organic compounds and aldehydes and ketones sampling test" method"

These two standards have played a great role in the control of in-vehicle pollutants in China's automobile industry, but there are still a series of problems in the control of volatile harmful substances

02 Research status of VOC detection methods for automotive interior materials in my country

In order to make the air quality in the car meet the requirements of the above standards, automobile enterprises need to detect and control the VOC emission of automobile interior materials and parts.

2.

The main principle of the bag method test method is to put the car interior parts in a sealed sampling bag to simulate the use of the sample in the car, pass an appropriate amount of nitrogen into the sampling bag, and then adjust the temperature and time as needed to make volatilization The organic compounds are volatilized into the sampling bag, and then certain gas samples are collected by Tenax tube and DNPH tube, so as to carry out qualitative and quantitative analysis of benzene hydrocarbons and aldehydes and ketones respectively[6]

This method is mainly used in Japanese auto companies and their joint ventures, and it is also the main method for domestic VOC detection

The sampling bag method is simple and easy to operate, and is not limited by the size of the sample.

Sun Chengwu et al.

2.

In addition to the detection of benzene hydrocarbons and aldehydes and ketones, this method can also be used for atomization detection, and this method can truly simulate the use of the sample in the car, and more intuitively study the change law of the VOC emission of the sample with time.

In addition, the volume of the inspection chamber is small.

Zhang Xiaoyan et al.

2.

The headspace method is more sensitive to the detection of benzene-based VOCs, the detection process is simple and easy to operate, there are few pretreatment steps, no organic solvent is introduced, and secondary pollution caused by solvents is reduced, and the headspace sampling bottle can be reused.

Qin Jianqiang [12] used the headspace method and the bag method to test the test samples respectively.
The test results show that the headspace method has good stability and sensitivity, and the linear range and stability of the detected benzene series VOC data are better.
It is better than the bag method, and the bag method is more suitable for the detection of aldehydes and ketones
.

Chen Lin et al.
[13] dried the sample, weighed a certain mass and put it into a headspace bottle, sealed it and put it into the headspace sampler, set the parameters of the headspace sampler, the headspace furnace temperature was 65 ℃, the quantitative tube The temperature was 100 °C, the temperature of the transfer tube was 110 °C, and the sample equilibration time was 30 min
.
Under this test condition, the content of benzene series volatile organic compounds in the samples was determined.
The results showed that the linear correlation coefficient of each benzene series standard curve could reach more than 0.
999, and the relative standard deviation was 4.
2% to 6.
9%.
The standard recovery rate was 97.
9% to 101.
5%, and the results were satisfactory, and the VOC content of benzene series in automotive interior parts could be determined more accurately
.

2.
4 Thermal desorption method Thermal desorption method is a method for measuring benzene hydrocarbon volatile organic compounds, which is widely used in European automobile enterprises
.
The method mainly uses thermal desorption-gas chromatography-mass spectrometry to analyze the content of volatile organic compounds released from auto parts and interior materials
.
The specific detection process is as follows: (1) Cut a certain mass of sample from the sample to be tested and put it into the thermal desorption tube; (2) Put the thermal desorption tube into the thermal desorption instrument, and decompose it at a given temperature for 30 minutes , so that the VOC in the sample is fully released; (3) GC-MS is used to detect the organic gas released from the sample to obtain the VOC content of benzene series and TVOC (total volatile organic compounds) content
.

Compared with other methods, this method is simple and easy to operate and has a high degree of automation
.
In addition, the thermal desorption tube can be reused, the test cost is low, and it is suitable for the detection of large batches of test samples
.
However, the sample test volume of this method is small, and the data representativeness is low
.

Hong Ying et al.
[14] placed the material to be tested directly in the thermal desorption tube, and used the thermal desorption test method to detect the content of volatile organic compounds.
The thermal desorption time was selected as 30 min
.
Results In the range of 10-500 μg/mL, the mass concentration of benzene series had a good linear correlation with the corresponding chromatographic peak area, the recoveries were 80.
3%-98.
1%, and the relative standard deviations were 3.
37%-5.
.
42%
.
This method has the advantages of simple operation, high extraction efficiency and full automation, and is suitable for the detection of volatile organic compounds in auto parts and interior materials
.
Wang Jinling et al.
[15] first used the micro-cell thermal extraction method to collect the samples, and then used thermal desorption-gas chromatography-mass spectrometry to determine the volatile organic compounds in the samples, and optimized the sampling time and flow rate
.
Results The recoveries of standard addition were 89.
1% to 94.
0%, and the relative standard deviations were 2.
13% to 5.
14%.
The results were satisfactory
.

2.
5 Formaldehyde volatilization method The formaldehyde volatilization method is a method used to analyze the content of aldehydes and ketones volatile organic compounds released from automobile interior materials, and is widely used in European automobile enterprises
.

The detection process is as follows: (1) Add 50 mL of deionized water into a 500 mL clean wide-mouth bottle, cut a sample of specified size from the sample, hang it in the wide-mouth bottle with an iron wire, and seal the wide-mouth bottle; (2) ) Put the jar into a 60 ℃ oven for a certain period of time, and then cool the jar to room temperature; (3) Take out a certain amount of solution from the jar and inject it into the volumetric flask, and add a certain amount of DNPH solution , to produce a chemical reaction between the two; (4) quantitatively or qualitatively analyze the reacted solution with a liquid chromatograph
.
The formaldehyde volatilization method is simple to operate and has low detection cost, but the test data is single, and it can only measure the content of various aldehydes and ketones volatiles, but cannot analyze the content of benzene hydrocarbon components, and the accuracy of the results of formaldehyde detection by spectrophotometry Therefore, this method is not widely used in China
.

03 Conclusion

This paper analyzes the status quo of relevant standards for VOC detection in China, and gives a comprehensive introduction to the detection methods of VOCs in auto parts and interior materials.
Each method has its own characteristics, advantages and disadvantages, and scope of application.
During the test, a simple and easy test method should be found according to the actual situation of the sample to be tested, so as to reduce the test cost and improve the accuracy of the test results
.
At the same time, relevant domestic enterprises can learn from the foreign automobile industry's experience in VOC detection of automotive interior materials, and combine the current situation of China's vehicle interior air quality to standardize VOC detection methods for automotive interior parts, and avoid harmful and highly volatile materials from the source.
It can improve the smell in the car and provide a safe, environmentally friendly and comfortable in-car environment for the vast number of consumers
.