Mastering the balancing act between quality, costs and sustainability are some of the key concepts that must be kept in mind in the application of automotive paints.
by Doris Schulz*
Improve ecological balance, increase efficiency and improve quality – these are the goals of the automotive industry and its suppliers do not overlook them in the painting process. Industrial paint technology companies offer innovative solutions to this end. The spectrum ranges from pre-treatment, equipment and the application of paint technology and systems, to the coating of films for the manufacture of components.
Whether for compact vehicles or luxury limousines - the color and paint provide the vehicle with a look that promotes good sales figures. And much more: a strong and lasting resistance to the inevitable mechanical, chemical and physical "attacks" during the life of the car is absolutely essential. At the same time, global competition increasingly requires a more efficient and sustainable painting process. A balancing act, for the solution of which the paint industry is continuously working, to improve existing options and the development of new ones.
The conservation of resources in pre-treatment
In order to provide metal car bodies and other auto parts with effective corrosion protection and good paint adhesion, they are subjected to conventional zinc phosphating during pre-treatment.
Increasingly, zinc phosphating, which contains heavy metals, is in effect replaced by nano-ceramic processes. This trend is based on the environmental and economic advantages of this multi-metal technology: the products are free of toxic heavy metals, which significantly reduces the cost of wastewater treatment, waste management, cleaning and maintenance of equipment. In addition, the coating can be applied at room temperature, by immersion or spraying before a wet coating and a powder coating which also leads to a reduction in costs.
In the pre-treatment of accessories and plastic interior parts, new technologies are increasingly being imposed, such as cleaning by 'CO2-Snow-Jet' (CO2 snowblasting) against the classic 'Powerwasher'. This, in part, is due to savings of up to 50% in investment, up to 20% in operating costs and up to 80% in the required area. Moreover, elongated systems can be easily integrated into the paint line.
The paint reduction process
Unfilled coating systems for vehicle painting are on the rise in the global environment, even in the 'Premium' class. From the filling function, usually a system based on water paint is taken over. Compared to conventional painting processes, by eliminating intermediate drying, 15% to 20% of the required energy can be saved.
At the same time, the fill-free process reduces solvent emissions and makes the area of the filling plant unnecessary. These economic and environmental advantages, meanwhile, have led to a trend in the coating of plastic accessories to switch to a two-layer finish without primer. For interior coating parts made by injection there are already solutions that give a highly glossy finish to the components with a single layer of paint.
Only the paint that is necessary
In order to achieve savings in paint, the motto is to eliminate potential sources of loss such as 'overspray' atomizers, losses due to paint change in the application and in the supply. Often, this can be achieved by selective modifications quickly and effectively.
One solution would be to increase the efficiency of the application by adapting the spray jet to the geometry of the part as well as electrostatic spray guns and rotational atomizers. With the latter, degrees of efficiency in the application of more than 90% are achieved. An important contribution in the use of hydro coatings are the new potential separation systems located directly on the robot arm. They also ensure minimized use of detergent and shorter times in color changes. In addition, such fine atomization results are achieved with electrostatic rotational atomizers, give the possibility of reducing the speed of descent of the air in the cabin and, therefore, energy savings are achieved.
The increased degree of automation by robots, even in the application of paint of car body interiors, also leads to lower paint consumption. Other advantages are the high reproducibility of the painting result and lower waste.
Another positive side effect of the use of paint robots is that, for the conditioning of the spray booth can be easily switched from fresh air systems to recirculation systems. This can result in substantial energy savings in the order of 60% to 70%.
An intelligent logistics system also leads to reduced material consumption. The 'Pigging' recovery system allows, for example, to recover the raw paint from the pipes or to transport, for special applications, well-defined quantities of paint to the site of the application technology.
Prolong the "new car effect"
Varnishes with matte effect are fashionable. They are robust, easy to care for, relatively insensitive and give, mainly to small series, an individual appearance. In glossy varnishes, emphasis is placed on increasing scratch resistance, so that the "New Car Effect" remains for longer.
For this there are innovative solutions that combine the advantages of "hard" inorganic materials and "soft" organic materials. A 'nano gel sun' process is also already being applied in series in the automotive industry. It is applied on anodized aluminum elements of high-class vehicles, to give them a transparent scratch-resistant protective layer. Other applications of sol-gel technology in the automotive industry are in the testing phase. The importance of UV varnishes in the automotive industry also continues to grow – both in the coating of plastic and metal substrates. The reasons are not only a high scratch resistance but also the saving of raw materials, energy and the reduction of harmful emissions.
Another benefit is the extremely short paint drying time. Through hardening with UV technology under inert gas atmosphere, the drying of large and complex components such as shafts is no longer an obstacle.
The path from pre-painted film to pre-painted component: The trend of saving energy with lighter and less expensive cars and electric vehicles is likely to inspire film technology as well. Here, for example, the films of polycarbonate mixtures, in the first step are coated with a thermoformable hydro base layer. This then receives a transparent layer consisting of a dual-curing UV varnish that is first thermally dried and covered with a protective film.
After cutting the film can be molded by a thermoformed process obtaining the desired shape, such as a roof module or a spoiler. The following UV hardening gives the component a very scratch-resistant surface. Its firmness is obtained by a filling of foam.
To highlight
PaintExpo confirms presence of 14 countries for 2014
PaintExpo revealed that it is already planning the organization of the 2014 version of the event on industrial coatings that will take place from April 8 to 11 in Karlsruhe (Germany).
The organization announced that more than 160 exhibitors from 14 countries have already reserved their stand for the next fair. The occupied area is more than 5,800 square meters and covers more than 50% of the total exhibition area of the event held this year, visited by more than 8,000 people from 63 countries.
Some of the technologies and products presented at the fair include coating equipment, application systems and spray guns, liquid and powder coatings, automation and transport technology, cleaning and pretreatment, drying and curing, environmental technology, measurement and testing, quality control, depainting, application of paint through a service lease contract, provision of services and technical literature.
* Doris Schulz is a specialist in the field of surface treatment, has her own public relations consultant who currently leads the Paint Expo 2013 fair in Istanbul, Turkey, which will take place from September 12 to 14 and Paint Expo 2014 that will take place from April 8 to 11 at Messe Karlsruhe, Germany. [email protected].
Photo courtesy: Eisenmann
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