Development trend of polypropylene materials for vehicles

Time：2021-12-22 09:34:52 / Popularity： / Source：

Development of automobile industry is accompanied by an increase in interaction between people and cars. In this regard, people have higher and higher requirements for corresponding parts and materials.

Development trend of polypropylene materials for vehicles

1. Requirements for scratch resistance

Polypropylene, raw material for automotive interior parts, is relatively low in hardness. Therefore, some parts are easily scratched, scratched or kicked during user's use. After a long time, surface of parts is obviously white and very ugly. Therefore, polypropylene materials must have scratch-resistant properties.
Specific requirements: Under a certain load, use specified scribe to draw 20 vertical crosses on the surface of sample, then evaluate brightness change of scribed position. Generally, brightness change is required to not exceed 1.5, that is, △L≤1.5. Commonly used loads are 5N and 10N, different loads can be selected according to part where parts are used or whether they are painted or not.

2. Anti-white mark performance

Decorative parts made of polypropylene materials tend to appear white during assembly or when they are subjected to external forces such as bending or impact, and over time, white marks will further expand, affecting aesthetics of interior. This is what everyone usually calls phenomenon of stress blushing. To avoid stress whitening, polypropylene materials must also have anti-stress whitening properties.
Specific requirements: Under a certain height, perform a falling ball impact test on sample, then evaluate brightness change and record it. After a period of time, re-evaluate brightness change of impacted part; then store sample at a high temperature, and re-evaluate brightness change of sample after a specified time.

3. Heat aging performance

Polypropylene material is easily oxidized by oxygen in air due to its own structure, especially when exposed to light and heat, it will accelerate aging, which will destroy its physical and mechanical properties, affect service life of parts. Therefore, polypropylene materials must have heat-resistant oxygen aging properties.
Specific requirements: as interior parts, at least 400 hours at 150℃ without chalking. Experiment can use the whole part, or part can be cut into splines and then carried out in a drying oven.

4. Dissemination performance

People have higher and higher air quality requirements for car interiors. Therefore, in order to ensure a good car interior environment, as interior parts, without exception, four requirements for emission performance must be met. Emission performance of interior parts includes odor test, formaldehyde content determination, condensation composition, and total carbon emission.
Specific requirements: odor score ≤3 formaldehyde content ≤10mg/Kg; condensed components ≤2mg total carbon content ≤50μgC/g.

5. Requirements for light aging resistance

When door is opened, parts that user can directly see can be directly or indirectly irradiated by sunlight. In order to avoid defects such as discoloration and deformation caused by sunlight, raw material itself must have performance of light aging resistance.
Specific requirements: First, determine degree of sunlight exposure according to specific use position of part, that is, whether it is directly or indirectly exposed to sunlight, then determine exposure period. Under certain irradiation intensity (uV), temperature, humidity and other conditions, after a certain exposure period, color fastness of sample should not change more than 4 (evaluated by gray scale), or △E≤1.7.

6. Anti-sticky performance

With wide application of polypropylene materials in automotive interiors, new problems have also been exposed. In atmospheric exposure, surface of polypropylene parts produces precipitates, at the same time sticky phenomenon occurs, and gloss of parts surface also changed accordingly. For this reason, polypropylene materials must have anti-stick properties.
Specific requirements: Simple thermal aging, sunlight simulation, and normal interior light aging experimental conditions cannot reproduce stickiness phenomenon, and it must be verified under more appropriate light aging conditions.

7. Good antistatic performance

You can observe that after a car has been used for a period of time, surface of some parts tends to attract dust. After a long time, dust has not been removed, it is getting dirty and difficult to clean. This is caused by static electricity. As polypropylene material is a non-polar polymer, it has good electrical insulation and is not affected by humidity, so it is easy to generate static electricity.
Above problems will appear over time. Severe static electricity can also produce shocks and even sparks. Therefore, polypropylene materials should also have antistatic properties. Antistatic property can be measured by indicators such as surface resistance.

8. Hand feeling requirements

Passengers are getting more and more in contact with car when getting in and out of car. Take hard plastic center console as an example. Every time you touch it, it is hard, and there are even some slaps on the edge. Corresponding high-end cars usually use solid wood or piano paint. In contrast, it is clear that current car companies mostly promote slush-plastic materials, and this soft plastic feels much better.

Gud Mould Industry Co., Ltd