Analysis of safety indicators and evaluation of automobile interior materials

Analysis of Safety Indicators and Evaluation of Automotive Interior Materials

The widespread use of automotive interior materials has made their safety an important research topic. This article presents the safety status and impact of interior materials. Influences on the human body and the environment, safety assessment indicators, standards and test methods for automotive interior materials, and the composition of pollutants in the vehicle are reviewed.

Automotive interior materials include composite fabric, skin foam composite, structural foam molding, injection molding and vacuum formed thin shell interior, as well as car seat fabrics, headliner fabrics and carpets. , curtains and door fittings, etc. The services concerned recently carried out air quality tests on board 100 vehicles,all within three years of use, and found that 46% had varying degrees of pollution. The safety of automobile interior materials involves many aspects, among which the problem of air pollution inside the car is particularly important. In 2008, the National Environmental Protection Administration held a discussion meeting on the limit standards for \"Car Air Volatile Organic Compound Concentration Requirements\" and initially determined eight elements and limits for air pollutants to control in cars. The concentration limits for formaldehyde and benzene are in accordance with GB/T1883 - The “National Indoor Air Quality Standard” 2002 states that they are set at 0.10 and 0.11 mg/m3 . In my country, the average content of 8H (TOTAL VOLATILE ORGANIC COMPOUNDS) in China (TOTAL VOLATILE ORGANIC COMPOUNDS) in China does not dmust not exceed 600 μg/m3, and the average formaldehyde content per hour cannot exceed 100 μg/m3, while the internal TVOCS of the car cannot The content is generally higher than this standard; therefore, it is necessary to establish a systematic safety performance evaluation system for automotive interior materials to standardize the automotive manufacturing and sales market, and carry out pollution safety tests in the cabin when using automobiles, especially during the initial purchasing process.

1 Automotive Interior Material Safety Evaluation Indicators

In 2004, the National Standards Administration and the National Environmental Protection Administration environment began to formulate the \"Concentration Limits of Air Pollutants in National Standard \"Vehicles and Measurement Methods\", based on the state of development.national automobile development and possible safety problems, to carry out legislative control on air pollution inside the car. The standard was promulgated and implemented in 2008. At the same time, with reference to the industrial environmental protection standard HJ/T400-2007 \"Measuring methods of air pollutants in vehicles\", the National Administration of Environmental Protection organized competent scientific research institutions to investigate and study the problem of air pollution in vehicles, and in 2009 In 2019, the \"Requirements for Concentration of Volatile Organic Compounds in Vehicles\" vehicle air” have been promulgated

Preparation Instructions. The aim of this series of works is to control air pollution caused by vehicle interior components and trim materials.

1.1 Concentration of air pollutants in vehiclesicles

(1) Damage caused by pollution in vehicles Drivers and passengers have long been exposed to a heavily polluted environment in vehicles. Over time, symptoms will appear. The concentration of harmful gases in new cars is higher. When the air conditioner is turned on in summer and the windows are closed, drivers feel dizzy, sleepy and cough, endangering the physical and mental health of drivers and passengers as well as the safety of people and vehicles. Therefore, it is necessary to establish various test standards to assess the degree of pollution in the car.

(2) Sources of polluted gases Pollutants in the car are mainly caused by the relocation of harmful substances contained in interior parts and non-metallic materials used for interior decoration, pollutants from the exterior of the car which is penetratingenter the car and pollutants from outside the car entering the car. The pollutants emitted by the automobile itself are made up of three parts. Volatile components such as organic solvents, auxiliaries and additives contained in plastics, rubber, fabrics, paints and adhesives used in automobiles release harmful substances and cause pollution. The main pollutants are benzene, toluene, formaldehyde, hydrocarbons, etc. ; pollutants entering from outside mainly include hydrocarbons, carbon monoxide, carbon dioxide, hydroxides, etc. ; the car itself emits pollutants through the exhaust pipe, crankcase, fuel evaporation, etc. Pollutants and dirt accumulated in the air duct after long-term use of car air conditioners will also enter the car. These pollutants includemainly contain hydrocarbons, carbon monoxide, nitrogen oxides, benzene, olefins, aromatic hydrocarbons, etc.

1.2 Flame Retardant

GB8410-1994 \"Combustion characteristics of automotive interior materials\" was officially implemented in January 1995 as a mandatory national standard to promote the healthy development of China\'s automobile industry. With the rapid development of the domestic automobile consumption pattern, the new GB8410-2006 standard was revised and released in 2006, and was officially implemented in July 2006.

The new standard is more conducive to quality inspection and expression of the result. The corresponding FMVSS302 is the US Federal Automotive Safety Interior Materials flame retardant standard. This standard is applicable to any component of various automobiles such as cars, commercial vehicles, trucks and buses, such as seat cushions, etc.

Backrests, curtainx, etc

1.3 Other indicators

(1) Atomization value. High-boiling substances in fur volatilize under certain conditions and become cold when exposed to cold. A mist forms on the windows, in particular on the windscreen. The fogging value is suitable for evaluating the fogging behavior of volatile organic substances in automobile interior materials such as PVC, textiles, leather, non-wovens, rubber and plastic products at high temperatures.< /p>< p>It can also be used for the determination of the high temperature atomization phenomenon of xenon lamps in front of cars. Although fur interior materials such as seat cushions, backrests, steering wheel covers, etc. have been widely used, there are currently no specific requirements for the atomization value, and fur materials for the interior of vCars on the market vary greatly, and some have atomization. values ​​above 25 mg. According to the DIN75201-B method, some domestic and foreign automobile brands and manufacturers generally require the atomization value of seat cushion leather to be ≤ 3-5 mg.

(2) Antistatic Static electricity will make the occupant (especially when wearing chemical fiber clothing) uncomfortable and will generate a friction discharge when leaving the seat. Phenomenon. Gasoline fumes or smoke from smoking may exist in the car, which can easily cause a fire under the action of static electricity. According to the mixing rate of general conductive fibers when weaving, generally when the specific resistance is 102 ~ 105 Ω cm, the fabric has good antistatic properties.

2 Index test method

2.1 Measuring the concentration of air pollutants inthe car

2.1.1 Measuring items

The measuring items include: car model, usage time, interior material composition, initial vehicle quality air inside the car, air quality outside the car, sunlight intensity and temperature inside the car, window opening status , the car\'s starting status and speed, and the air conditioning activated. situation, place of sampling.

2.1.2 Test method

(1) Equipment: 6 taxis, 6 private cars and 6 buses each, air sampler, thermometer, photometer, sunshade net, etc.

(2) The test method selects taxis, passenger cars and buses that are new, 3 years old and 6 years old. old, and the interior materials are divided into non-leather textiles and leather seats. Six vehicles; park overnight in the carport with the windows open and measure the initial concentrationthe of air pollutants in the car with the windows closed. The car is parked in the sun and the air inside and outside the car, at driver\'s head level, is sampled. Samples are taken every 30 minutes, light intensity and temperature are measured at the same time and the evolution curves of the concentration of air pollutants, temperature and light intensity in the car with time are traced. Perform separately under other unchanged conditions: ① Use sunshade net to block the sun; ② Start the car without turning on the air conditioner and without driving; ③ Start the car with the air conditioner on but not driving; ④ Driving on the highway with the air conditioner on and without the air conditioner respectively. ; ⑤ Don\'t turn on the air conditioner, open the windows, and drive on the highway with half or full windows; ⑥ Turn on the air conditioner andthe rest of the conditions are the same as ⑤. Draw a curve for each test.

(3) Analysis of test results According to the change curve, the functional relationship between the concentration of air pollutants in the car and various influencing factors is obtained to determine the standards for concentration limits of air pollutants in the car under different circumstances.

(4) Determination of limit values ​​Establish two tables of concentrations of air pollutants in vehicles with interior materials containing leather and without leather, respectively, and use the conditions under which the highest value is obtained for each test as standard test conditions, and then determine the concentration limit value of each indoor air pollutant according to ordinance with GB/T 1883-2002 “National Indoor Air Quality Standard”.

2.2 Fireproofing of materialsAutomotive Interior Materials

Automotive interior materials should have good combustion and flame retardant properties to ensure that once the car catches fire, passengers will have enough time to leave. Combustion performance includes the flammability of the interior materials, the flow properties of the melt, and the content of harmful gases volatilized during the combustion process. The flammability test is divided into limited oxygen index and combustion characteristics. The first is the minimum oxygen content in the air required to sustain the flame of the material. . Burning characteristics include whether the material can continue to burn away from the source of ignition, the rate of continued burning, whether it can burn without flames, and melting and dripping performance. These properties and the composition of the material, thickness, whether the surface is fluffy, vertical, etc. are determined. During thests, select four samples of each inner material and place them in the combustion chamber.

First use a lit cigarette to blow out enough air to observe whether it can ignite the inner material. Use a fire source to ignite the material and gradually increase the oxygen concentration in the box, and record the oxygen concentration at which the material can continue to burn. During afterburning, observe the speed (mm/min) and length (mm) of the afterburner. If the cigarette butt can ignite the material, the sample is a flammable material; For flame retardant materials, the sample cannot continue to burn after being placed in the flame for 20 seconds.

2.3 Other safety properties

2.3.1 Antistatic properties

(1) The standards for antistatic fibrous materials are general. The specific resistance of the synthetice fiber is greater than 1013Ω·cm, and it is 108-1010Ω·cm when mixed with anti-static fiber, and it can be reduced to 10-2-105Ω·cm by adding carbon black conductive fiber . When the general conductive fiber has a specific resistance of 102-105Ω·cm, the fabric has better antistatic performance

(2) General methods to improve antistatic performance ① Treat the fiber or fabric with surfactant Hydrophilic treatment to improve the hygroscopicity of fibers or fabrics and accelerate the dissipation of charges; ②Introduce hydrophilic groups on fiber polymers, or use fiber polarity to eliminate static electricity or prepare antistatic fibers; ③ Applications of conductive fibers include metal fibers, carbon fibers, conductive polymer composites, and coatings to reduce fiber resistivity.

2.3.2 Anti-fog

(1) Pprinciple of atomization test The sample is heated in the misting cup and begins to volatilize, and the volatile gas is cooled by the cooling chamber Condense on the glass plate or on the aluminum foil; after the condensation is completed, remove the glass plate or aluminum foil, measure the atomization value or weight of the condensed components on the glass plate or aluminum foil, and compare it with the data before condensation, in order to obtain the test The same atomization volatility characteristics.

(2) Anti-fog performance standards include DIN 75201, ISO6452, SAE J1756, QB/T 2728, PV 3920, PV

3015, NES M0161 and many other standards.

3 Conclusion

With consumers\' increasing demands for automobile comfort and safety, the way to scientifically assess the safety of automobile interior materials is become a question iimportant for automobiles. Common requirements of car manufacturers and users. Attention to the air quality inside the car and the establishment of limit values ​​will help car manufacturers and their auto parts to establish and gradually improve the release performance detection and monitoring system volatile organic compounds in the air of the products. Therefore, the automotive interior material safety analysis will provide the corresponding theoretical basis and basic experimental data for the establishment of an evaluation index system and standards.

Prev: Comparison of artificial leather and application of PU synthetic leather in automobile interiors