The modern society is under the pursuit of lightness, comfort and environmental friendliness, making lightweight a popular tendency. In the transportation industry as well as the production and usage of aeronautic component, the need of light weight is even more highlighted
It is known that the application of low-density material could effectively reduce the load weight thus cut down the fuel consumption and carbon emission to protect the environment. According to the study statistic, for every 10% reduction in vehicle weight, the fuel efficiency can be increased by 6%-8%. That means, if the car weight could be brought down by 100kg, the fuel consumption per 100 km would be reduced by 0.3-0.5 liters. Besides, low-density material also means less demand of raw material in the manufacturing process which conduces to the conservation of natural resources.
The expandable microspheres can serve as light weight additive or blowing agent for a wide range of materials namely thermoplastics (such as PP, PE, PVC, PET, TPR, TPU, TPV, PA, PC, PBT, PET), thermosetting plastics (such as polyurethane, epoxy resin, Phenolic resin), rubber (such as EPDM rubber, natural rubber, styrene butadiene rubber), cement, ceramics, artificial marble, plaster and paper/cardboard.
In addition, it is very convenient to use in the application. Usually, it is not necessary to change the material or process to achieve a good overall effect. At the same time, it can bring the following advantages:
- Reduce the density of products by a large margin
- Reduce the cost of raw materials and transportation.
- Control the warpage and shrinkage of injection parts;
- Reduce the dielectric constant of the material.;
- Reduce the cooling time of materials, shorten the overall forming cycle and improve productivity. However, it is also unavoidable that the microsphere expansion will cause voids in the matrix material and reduce the break elongation and tensile strength of the material. Nevertheless, this reduction is much lower compared with the density reduction it brings.
1Glass Mat reinforced Thermoplastics
As people’s understanding of the automobile energy consumption and the sustainable development goes profounder, lightweight of vehicle and environmental friendliness have been attached great importance and become a growing trend. As an environmentally-friendly material with potential lightweight capacity, lightweight GMT has received wide attention.
GMT with microspheres has the following advantages:
- Weight reduced from 1000g/m2 to 600g/m2.
- Volume increased and thus load-bearing capacity gets higher, thickness increased 2-3 times.
- Physical and mechanical properties improved by 20% owing to the support for glass fiber given by microsphere.
- More stable size due to the internal pressure and resilience of the microspheres.
- Sound and heat insulation.
2Vehicle underbody coating (UBC)
The chasis and the skirt of a car are usually exposed to abrasive condition with dust, gravel, stones, or corroded by climatic factors like water, moisture, ice, salt and even acid rain. In order to avoid the above-mentioned effects, a 400-1000 μm-thick coating is necessarily needed. Generally speaking, middle and high class sedans need to wear a UBC of 8.5-9.5 kg
For cost-effective purpose, automobile manufacturers expect the car to be as light as possible. Meanwhile, it should not affect the wear resistance and corrosion resistance of the primer while meeting the need to reduce environmental pollution.
Provided adding expandable microspheres to the UBC, after baking and curing process, the following advantages can be achieved:
- The product is 50% lighter when it reaches the desired thickness;
- Environmentally friendly and non-toxic;
- The traditional foaming process usually fails to form uniformed forming holes. The bubble created have diverse sizes and irregular distribution, which will interactively influence the utter surface. Holes and unbalanced structures weaken the mechanical properties, resulting in poor wear resistance, corrosion resistance and moisture retention. In contrast, the expandable microspheres possess dense structure which well integrates with the highly resistant matrix to produce comprehensive protection;
- Sound and heat insulation.
3Ultrahigh temperature thermoplastics
The ultra-high temperature expandable microspheres, such as PP、PA、PC、PET/PBT、PPS, are applied to thermoplastic materials with a injected molding temperature of no less than 210 ℃. During the injection molding process, the microspheres are thermally expanded to achieve controlled foaming, which helps to form a uniform sealed micro-porous structure and to improve the mobility of the plastic. Meanwhile it reduces the density and make a uniformed temperature in each part of the piece during the molding and cooling process. All above effects help reduce the risk of warping.
When it comes to the injection molding of engineering plastics, the addition of ultra-high temperature expandable microspheres can save cost by decreasing the product density by about 15-30%.Taking PC material injection molding as an example, how to reduce weight without adding ultra-high temperature expandable microspheres has always been a headache for many enterprises. Now it is no longer the case. The density of PC products could be brought down by 30% with only 2% of ultra-high temperature expandable microspheres, under the circumstance of molding temperature of 260 ° C, injection pressure of 65 MPa and cooling time of 45 s. However, it is also not avoidable that the microsphere expansion will cause voids in the matrix material and reduce the break elongation and tensile strength of the material. Nevertheless, this reduction is much lower compared with the density reduction it brings.