About the application of automotive body powder coating and Interpon ultra-weather-resistant polyester powder coating

Compared with the traditional liquid paint coating process, powder coating has the advantages
of easy operation, recyclable coating, easy maintenance and cleaning of equipment, almost zero VOC emissions, less waste generated and non-toxic, small footprint, low investment and low total operating costs.

Interpon ultra-weathering polyester powder coatings have been recognized and applied
by many internationally renowned brand automobiles.
Interpon powder coatings have been tested to meet the automotive OEM standard in-line coating coatingol.
com
in terms of color, appearance, weatherability, chemical resistance and environmental aging resistance.

Advantages of powder coating for automotive bodies

The automotive manufacturing industry is in a changing period, and in the face of emerging markets, automakers must strive to reduce costs and increase production efficiency
.

At the same time, in order for customers to remain loyal and increase market share, product quality
must also be improved.

In this context, vehicle coating engineers are required not only to develop and apply advanced coating technology, but also to reduce the footprint of the existing coating line, that is, to reduce the process of spraying process, which is also an effective measure to
save energy, protect the environment and reduce production costs.

Powder coating is a preferred solution
to achieve energy saving, environmental protection and reduce production costs by reducing the spraying process.
Specifically, the advantages of body powder coating are reflected in the following aspects
.

1 Good environmental protection

"Three wastes" pollution has become a worldwide issue, among which solvent-based paint coating to the atmosphere pollution has attracted widespread attention from all countries, and the restrictions on VOC emissions from automobile painting have become more and more stringent
.

Driven by strict environmental regulations, powder coatings, like other green coatings, have been rapidly promoted around
the world.
Traditional liquid spraying processes can reduce VOC emissions by increasing energy consumption
.

The car body powder coating has zero VOC emissions, and produces less waste and is non-toxic, eliminating the need to use the exhaust gas combustion chamber and/or other methods to treat the exhaust gas
generated during the curing process.

With the development of powder coating technology, the application field of powder coatings will continue to expand, and the proportion in industrial coatings will also increase, so powder coatings will be one of
the fastest growing coating varieties.

2 The process is simple, the footprint is small, and the paint can be recycled

Powder coatings typically require less space than traditional liquid coatings, reducing the spray booth footprint
.

Since there are no paint film drawbacks such as sagging and air bubbles that can occur during the traditional liquid paint spraying process, the powder coating operation is also easier
.

At the same time, due to the use of electrostatic spraying method, the thickness of powder coating can reach 40~50μm in one spraying, which improves the coating efficiency, and the powder coating can be recycled, and the powder coating equipment is easy to maintain and clean, reducing downtime and required labor
.

Save energy

Powder coating requires less energy than liquid coating systems
.
The powder coating booth keeps the air in a closed cycle, and the energy consumption required for its operation is greatly reduced
.

Although the curing temperature of the powder coating is high, this is offset by the large energy savings in the spray booth
.
Some OEMs estimate that the energy consumption of powder coating booths is 80%
lower than that of liquid paint booths of the same size.

Another major reason for energy savings is that exhaust gas treatment
is not required.
It is estimated that the electricity and natural gas required for powder coating are only 1/3~1/2
of traditional liquid coating.

In 2005, Haden's Jeffery Johnson compared
the coating equipment and production costs of automotive body primers for powder, waterborne and solventborne coating systems.

It is estimated that powder coating can save 2.
5 euros per vehicle compared to solvent-based painting and 6.
30 euros
compared to water-based coating.
This shows that the production cost of powder coating is 38% lower than water-based coating and 10%
lower than solvent-based coating.

Improve coating quality

Powder coatings offer excellent properties and provide high-quality protection to replace one or more coatings
in traditional liquid coating systems.

For example, the liquid coating applied to the wheels and many exterior parts of the body (topcoat primer + topcoat cover varnish) has been replaced
by powder coating.

In addition, powder coating can obtain the appearance quality that liquid coating cannot get, and the use of powder coating allows manufacturers to produce unique, difficult-to-replicate colors and effects, which contributes to the innovation of
vehicle styling design.

Improve the operating environment for workers

Workers are satisfied with
the use of powder coatings.
The system is odorless and significantly reduces the need for
protective equipment.
Spraying equipment is easy to use, clean and maintain, and this ease of operation reduces training time
for operators.

Interpon ultra-weather-resistant polyester powder coating

According to the requirements of automotive weather resistance and appearance leveling, AkzoNobel has developed Interpon ultra-weathering polyester powder coating and applied it to the coating of automobile bodies, which has achieved good results
in reducing paint consumption, simplifying the coating process, shortening the coating time, reducing production costs, saving energy and reducing emissions.

Interpon ultra-weathering polyester powder coatings not only provide good flexibility, extreme chemical resistance and excellent UV resistance, but also provide a protective layer against stone chips and prevent the body color from becoming "dull" due to washing, thus providing a smooth and "heavy" appearance
to the vehicle.

Compared to the previously used acrylic powder coat / clear varnish dual coating system, Interpon ultra-weathering polyester powder coatings offer significant advantages in terms of weather resistance, becoming the first truly environmentally friendly alternative to liquid coatings, ushering in a whole new era
for automotive coatings for automotive manufacturers.

Performance requirements for Interpon coatings

appearance

Taking powder coatings with white high-gloss colors as an example, the requirements for other colors are similar
.
a.
Film thickness: 60~80 μm
.
b.
Ggloss: >80% @(20°) or >90%@(60°).

c.
Orange streak meter test results: DOI >85, longwave < 10, shortwave <25, R <7<b13>.

Weather resistance

The weatherability test results of Interpon powder coatings are shown in Figures 1 and 2 (tested according to SAE 1960).

It can be seen from Figure 1 that after 1 year (12 months) of exposure in Florida, the gloss retention rate of the coating is above 90%; After 6 years (72 months) of exposure, the gloss retention rate of the coating is more than
80%.

As can be seen from Figure 2, the gloss retention rate of different color coatings varies after being irradiated with a xenon lamp
.
This is due
to the different absorption and reflectivity of light by powder coatings of different colors made of the same resin.

Corrosion resistance

1.
Salt spray test Salt spray test is carried out according to ASTM B117, and the specific requirements are as follows
.

a.
Test time: 500 h
.

b.
Unilateral corrosion length: ≤2.
5 mm
.

c.
Blistering level: 0 grade
.

d.
Surface rust grade: 0
.

e.
Adhesion level: class 0 or 1
.

2.
Cyclic corrosion test The cyclic corrosion test is carried out according to ASTM D1654, and the specific requirements are as follows
.

a.
Test time: 60 cycles
.

b.
Unilateral corrosion length: <3 mm<b10>.

c.
Surface rust grade: 0
.

3.
D870-2004, the specific requirements are as follows
.

A.
Time: Soak at ambient temperature for 240 h
.

b.
Blistering level: 0 grade
.

c.
Adhesion level: class 0 or 1
.

4.
Resistance to continuous condensation and humid climate The ability to resist continuous condensation and humid climate is carried out according to ASTM D1735, and the specific requirements are as follows
.

A.
Time: 96 h
.

b.
Blistering level: 0 grade
.

c.
After the sample is taken out of the test environment (temperature is 4 0 °C, humidity is 100%), it is placed in an environment of 23 °C and 50% humidity for 15 minutes before adhesion test, adhesion: class 0 or class 1
.

5.
Cold and hot cycle test

a.
Time: 15 cycles (2h at 30°C, 1 cycle for 2h at 80°C).

b.
Qualification criteria: no blistering and loss of light, and the adhesion is not reduced
.

Stone chip resistance test

Stone chip resistance tests are carried out
according to SAE J400.
OEM automotive manufacturers require outdoor decorative parts to pass this test, as shown in Figure 3
.
The coating system of the sample shown in the figure is as follows
.

Steel substrate Powercron 590 electrocoat AKZO156G metal powder topcoat primer PC752-71-2 low-gloss Interpon powder topcoat varnish

Comparison of powder coating and liquid paint coating

Paint consumption

The use of the Interpon powder coating process can reduce the consumption of coating, which means lower coating costs, as shown in Figure 4
.

As can be seen from Figure 4, the total thickness of the liquid coating film is 85~100μm (3 coatings), while the total thickness of the powder coating film is 75~80μm (2 coatings).

By reducing the number of coatings, the coating process can be simplified, the required coating time can be reduced, and the coating efficiency
can be improved.

Simplify the coating process

Powder coating with Interpon ultra-weathering polyester powder coatings simplifies the coating process, see Figure 5
.

As can be seen from Figure 5, liquid paint coating requires 3 drying times and 1 flash drying, while powder coating requires only 2 drying times, simplifying the production process and shortening the production process
.

Painting time for a single trolley

A comparison of the time required to paint the same body body with different painting systems is shown in Figure 6
.

As can be seen from Figure 6, the Interpon powder coating process takes less time than other coating processes, improving production efficiency
.

The cost of painting a single vehicle

A comparison of the cost of coating the same body with different coating systems is shown in Figure 7
.

Compared to System 1, raw material costs for single-coated powder coating can be reduced by 25%, and total energy and raw material costs can be reduced by 35%.

Emission reduction

Compared with other liquid coatings, powder coating reduces CO2 emissions by more than 60% (Figure 8) and VOC emissions by more than 95% (Figure 9).

Interpon ultra-weathering polyester powder coating application example

Interpon ultra-weather-resistant polyester automotive topcoats have been applied to outdoor decorative parts of international brand cars, as shown below
.

a.
USA: GM, Ford, Chrysler
.
b.
Europe: Audi, Fiat, BMW, Jaguar, Volvo, Citroen
.
c.
Asia: Toyota, Suzuki, Tata, Hyundai, Kia, GM-Daewoo, Ssangyong
.

Since 2007, India's Tata has coated at least 20,000 ACE microvehicles with powder coating (Figure 10).

Figure 11
shows the cab of a truck painted on the powder coating line of China Jirui United Heavy Duty Truck.
Interpon powder, when used as a primer for automotive body coatings, provides excellent corrosion resistance and stone chip resistance and has been used in the United States (Chrysler) and Europe (Scania) (Figure 12).