sign in sign up
<<
Home , Plastic, Vehicle

OPTIONAL SUBLINE OPTIONAL SUBLINE How to refinish . Contents.

Plastics: An exemplary career 3

Rough overview of different types 4

Plastics are indispensable 5

Automotive plastic types 6 2/3 Acronyms of frequently used plastics 7 Important plastic types in detail 8

Why paint plastics? 10

Plastic parts in the bodyshop 12

Getting paint to adhere on plastics 14

Causes of refinishing flaws 16

Reliable color matching for plastics 18

Technical Data Sheets and refinishing systems 19 Plastics: An exemplary career.

In addition to such terms as the One plastic is not the same as the next, “industrial age”, the „nuclear age“ so the challenges facing refinishers are or the “space age”, our era should consequently growing, together with the really also be described as the need for detailed information on the use “plastics age”, for quite a few of plastics on motor . The first achievements would have been question to be answered is therefore: virtually impossible without the “What are plastics?“ of plastics. A wide variety of terms are used in eve- In 1862, a British scientist, Alexander ryday life to describe one and the same Parkes, invented a hard -colored thing, such as plastics, rubber and synthe- which he called Parkesin. A long, tics as as PP/EPDM, and stony lay between this first plastic ABS. material and the use of modern plastics in motor but that is a different story Some of these are merely overall terms altogether. for plastic in general, while others refer to specific plastics with different The first plastic material was invented 27 properties. It is exactly these different years before Gottlieb Daimler presented properties which may lead to unpleasant his with to the general surprises when refinishing plastics. public and laid the foundations for , today s automobile . As early as the late 1970s, Standox laun- ched a compact yet complete plastics Plastics have been an indispensable ele- refinishing programme, which has been ment in modern motor vehicles for seve- improved and refined over the years in ral decades. For a long time, they were close cooperation with the automotive only used for the compartment industry. The programme provides body- and such classical external components as shops with proven products that ideally bumpers, spoilers or housings, but meet their day-to-day requirements. In nowadays they are also used as body special training courses and workshops, panels. , and bonnets are refinishers gain valuable knowledge on increasingly made from different types how to handle automotive plastics. of plastics and must be repaired when damaged. Rough overview of different plastic types.

Plastics are made up of individual components known as molecules. These molecules can be strung together in large numbers to form long chains known as .

Thermoplastics. These materials are used for and is the name given to spoilers on motor vehicles. plastics made up of separate linear or branched macromolecules which, however, Thermoset materials. are not linked together. As the number of cross-links increases, the material becomes harder and more brittle. Due to their many positive properties, The numerous molecular chains now form thermoplastics are the most commonly a single network. These extensively cross- used plastics in vehicle . linked plastics are known as Thermoset Materials. Thermoplastics can be melted and reused several times. This is an important factor They cannot be welded, dissolved or where environmental protection is con- expand like . cerned. Provided that different types are not mixed together, thermoplastics are Instead, thermoset materials are highly ideal materials for , because resistant to heat and this is why they are theoretically new parts can be made used for housings in the compart- from old parts. ment, for example.

Another advantage is that cracks and 4/5 fractures can be sealed by Elastomers. “Cross-linking“ is the term used when macromolecules are linked together more or less strongly. When only a small number of individual molecular chains are cross-linked with neighbouring chains, elastomers are formed.

Elastomers cannot be melted and reused, although they can still expand and display rubber-like properties. Plastics are indispensable.

There are many reasons for using But plastics have even more advantages. plastics in automotive . Due to the elasticity of the materials, for Most importantly, they help reduce instance, minor damage is reduced. vehicle weight without compromising Other benefits include greater occupant on safety. In addition to purely func- comfort, reduced noise emissions and a tional aspects, however, plastics also longer vehicle life. play a major part with regard to the shape and of a . In view of these positive properties of plas- tics, the trend in vehicle manufacturing is The percentage of plastics used in vehicle towards body shells that can ideally be manufacturing has more than doubled combined with plastic body parts. since the 1980s. Researchers and devel- opers assume that by the year 2010 one From market niche to mass market. in six kilogrammes of a vehicle`s weight “Pimp my “ - the tuning scene is increas- will be accounted for by plastics. The per- ingly relying on plastic body parts. centage of plastic body parts is growing constantly due to new materials and com- It all began in the 1990s, with plastic add- posites. Instead of producing the , on parts such as spoilers, air scoops and grill, bumper and separa- side skirts. Notwithstanding some ups and tely, as in the past, these four parts are downs, this trend remains with us today. now combined into a single integrated Plastics are easily moulded into ever more side-and-front element. extreme body transformations leading to the development of exotic pro- The possibilities for shaping and process- duced in limited – and sometimes tiny – ing plastics are virtually unlimited. This production runs. not only opens up new possibilities for the designers, but also permits considerable savings in consumption. The weight of a car made from composite materi- als is easily 10% lower than the weight of a „traditional“ metal door. This shows that plastics make an important contribution to reducing fuel consumption. Rule of thumb: A 100 kg reduction in weight saves 1 litre of fuel over 100 km.

green: typical plastic parts such as covers, bumpers, mirror housings, side skirts, trims. blue: optional plastic parts such as bonnet, mudguards, doors. Automotive plastic types.

“Blends” (e.g. PP/EPDM) are fre- quently used in addition to the pure form. A blend is a of diffe- rent plastics and corresponds to an “alloy” in metals.

“Blending“ allows for several desirable properties to be combined in a new plastic material.

The trade names coined by the individual plastics manufacturers are also commonly used, but rarely give any direct indication of the type of plastic involved. 6/7 Acronyms of frequently used plastics.

Chemical name Acronym Trade name(s) Automotive parts

Polypropylene/- PP/EPDM Stamylan P, Sabic PP, Purell, Bumpers, rear spoilers propylene-diene- Novolen, Moplen, Kelburon, Hifax, Forprene

Acrylonitrile butadiene ABS Bayblend, Relac, Mirror housings, wheel covers, Magnum, Lustran ABS roof box, front and rear spoilers

Polyamide PA Minlon, Akulon, Zytel, Wheel covers, fuel flap Vestamid, Ultramid

Polycarbonate PC Makrolon, Xenoy, Lexan Bumper panels, radiator grilles

Polyphenylene oxide PPO Noryl, Laril Body parts, e.g. mudguards, hatchbacks

Acrylonitrile-styrene- ASA Luran S, Kibilac, Geloy Radiator grilles, front and rear spoilers

Styrene-acrylonitrile SAN Luran, Tyril, Lustran SAN Radiator grilles, front and rear spoilers

Polyurethane PU Bayflex, Baydur, Irogran, Bumper elements, rear spoilers Estane

Polyethylene terephthalate PBT Pocan, Crastin, Ultradur, Body parts, e.g. mudguards, Vestodur hatchbacks

Unsaturated UP Roskydal Hatchbacks, add-on parts, sports car parts

Epoxy resin EP Araldit Components for racing cars

Polyvinyl chloride PVC Vestolit, Solvic , bumper strips Important plastic types in detail.

PP PA Polyamide PP/EPDM Ethylene-propylene- Wheel trims are now made almost ent- diene-copolymer irely of PA, a tough and resilient material Body parts made of this material are with high rigidity and strength. PA is large- usually manufactured as blends. Complex ly resistant to most organic solvents. injection-moulding plants are required for manufacturing large parts. For this rea- Molecular water is reversibly bound wit- son, they can be produced particularly hin the molecular structure, i.e. it absorbs cost-efficiently in the large numbers water from the ambient air and releases required by the . water to the ambient air. This explains many of the material`s positive proper- Depending on the composition in ties, although it can have an adverse each case, unprimed PP or PP/EPDM effect on the adhesion of a , as can cause problems with regard paint the water may deposit directly on the adhesion. surface.

PP was for many years considered impossible to refinish by bodyshops on PC account of its non-polar nature. Standox This material features seve- played a pioneering part in solving this ral outstanding properties, some of which problem with the development of its are also obtained with other plastics, but Standoflex system. Thanks to ongoing which are only found in their entirety in , Standox is . These properties include: today still regarded as an expert in the · High mechanical strength, even at very 8/9 field of plastic refinishing. low temperatures (down to –100 °C). · Good resistance to weathering.

ABS Acrylonitrile butadiene styrene ASA Acrylonitrile-styrene- ABS plastics are both tough and rigid. They owe their toughness to the rubber ASA forms a brilliant and scratch-resis- component (butadiene) and their rigidity tant high-quality surface and can also be to the acrylonitrile component. made transparent. Matt surfaces can be produced with the addition of matting Parts made of ABS materials should not agents. be left out-of-doors without protection and exposed to UV radiation for any ASA is characterised by excellent resis- length of time. Like all plastics containing tance to liquid substances including rubber, they gradually lose their tough- aggressive chemicals. ASA is also highly ness and become brittle. resistant to , fats, etc.

8 PU UP Unsaturated -fibre- All these plastics are structural foams, the reinforced polyester and flexibility of which can be BMC Bulk Moulding varied extensively. Structural foams have Compound a cellular core that becomes more and SMC Sheet Moulding more compact the further it is from the Compound centre and which is virtually sealed on UP-GF was better known as GFK (glass- the surface. fibre-reinforced plastic) for a long time. However, these materials must now be Flexible PU foam has an extremely elastic differentiated more accurately, since core with very high resilience, i.e. the numerous plastics are reinforced with material will return to its original shape glass fibre. even after an extended period of defor- mation. The use of glass-fibre-reinforced UP for large body parts, such as bonnets, boot lids or wings, is common practice for TPU Thermoplastic low volume production and in the tuning polyurethane sector. RTPU TPU, Reinforced thermoplastic SMC and BMC are the most commonly polyurethane used processes employed by the auto- RTPU and TPU are recyclable thermo- motive industry. plastics. This is an increasingly important advantage for the automobile industry, BMC comprises chalked-filled UP resin particularly in times of strict recycling and chopped strands. The plastic parts regulations. made from this material are injection- moulded under high pressure and high Parts made from these thermoplastics temperature. display all the various properties charac- teristic of every polyurethane: SMC are sheets and panels of polyester · High rigidity. resin with two-dimensional glass fibre · Dimensional stability under heat. reinforcement, which are moulded under · Good low-temperature impact pressure and at high temperatures. strength. · Can be coated. fibre is characterised by its high · Resistant to corrosion. strength and low weight as well as by its attractive appearance. Due to the high manufacturing costs, carbon fibre is normally used only in motor sports and for premium priced cars.

PVC PVC is one of the most versatile plastics due, not least, to the fact that it can be produced with a wide variety of proper- ties, from rigid to rubbery. Why paint plastics?

Although plastics can now be produced in all colors and with a matt or a glossy surface, in many cases they still have to be painted.

On the one hand, plastics must be paint- material. Refinishers, on the other ed for aesthetic reasons: hand, are faced with a number of basic problems: · Individual coloring to match the paint- of the vehicle body. · The parts are not identical or even · More gloss or color brilliance by similar; they are always made of adding. different types of plastics with · Elimination of manufacturing defects. different design and functions. 10/11 · Bodyshop conditions and resources At the same time, the plastic material may vary considerably. must be protected, because it is exposed · The parts are presented in different to the elements day after day and will conditions, i.e. as new or repaired age as a result. parts.

It is almost impossible to imagine plastics Since the 1980s, plastic components have corroding or degrading, but like most been marked on the back in accordance other materials, they also age and with VDA Recommendation 260*. The degrade when exposed to moisture and acronyms used are standardised in DIN UV light. EN ISO 1043-1 and DIN ISO 1629.

Factory-finishing plastics by the automotive industry or its suppliers is a standard, high-volume operation using parts identical in shape and made of the same plastic

*) Distributor: DOKUMENTATION KRAFTFAHRWESEN e.V. (DKF) Ulrichstr. 14, D-74321 Bietigheim-Bissingen Now that the type of plastic is identified, Example: : it has become easier to draw up specific Many helmets are made from polycarbo- recommendations for painting the plastic nate (PC), a highly shock-resistant plastic concerned. that can be coated using suitable paint materials. Consult the practical section for further information on how to deal with older Polycarbonate is highly sensitive to solvents. vehicles containing unidentified plastics. Unsuitable cleaners or paint materials may harm the polycarbonate and lead In some cases, the carmakers specify that to microcracks in the plastic material. As certain components must not be coated a result, the protective function of the for functional reasons. Such restrictions may be affected and the helmet must always be observed. may break in a crash.

Abbreviation for the main component contained Filler or reinforcing materials, possibly proportion in the plastic. of filler or reinforcing material. Plastic parts in the bodyshop.

Before starting to refinish a part, the refinisher should observe a few important basic rules and thoroughly inspect the plastic part concerned. Is it an old or a new part? Painted, primed or untreated? Answers to all these questions and more can be found in the following paragraphs.

Painted old parts. Plastic-welding is the ideal method for the part and ensuring that it is apparently Old parts which have already been coated repairing thermoplastics, although tho- as clean as possible. must be carefully examined: rough training and a detailed knowledge of this are essential. The risks of old plastic parts relate to · Is the part damaged? their unknown history. Utmost care · Does the paint adhere Unpainted old parts. and great experience is required everywhere? Such parts constitute the most critical to avoid mistakes when refinishing · Are there any cracks to be seen? substrates, since their history will always such parts. · Is the paint resistant to solvents? remain unknown to the refinisher. What has happened to the plastic since It goes without saying that any defects the vehicle was delivered to its owner? found must be repaired before continu- ing, provided that the effort required · Has it been looked after? does not exceed the cost of a new part. · If so, what care agents were used and This is then followed by: cleaning, sand- how? ing, renewed cleaning and finally appli- · Has the plastic material absorbed wax cation of the paint. or from polishes or preserva- tives? Repairing damaged plastic parts: · Can these agents be removed? Special repair kits approved by car makers for repairing damaged plastic These questions cannot always be parts are available for most materials. answered retrospectively, with the result Minor scratches can be eliminated quickly that adhesion of the refinish may be and easily with a suitable fine stopper. impaired in spite of thoroughly preparing Uncoated new parts. Primed new parts. The most important rule to be observed The primers used here differ considerably, is that: and their composition and suitability for subsequent processing remain unknown. The must be free from release Preliminary tests are recommended and the agents! the manufacturer`s instructions (e.g. those 12/13 enclosed with the product) can prove Clean the parts thoroughly in accordance useful. with the Standox TDS recommendations. Standox can offer the ideal tailor-made If unknown primers from other manufac- or universal systems for the subsequent turers have been used and information coating process. For more tips on how for further processing is not enclosed to remove the different release agents, with the plastic part, it is impossible to please see the following pages. make any reliable assessment of whether or not certain criteria are met, such as: Coated new parts. If the existing coating is found to be · Adhesion between and plastic. intact, coated new parts can be refin- · Suitability for coating with primer ished without difficulty. fillers, topcoats or other Standox products. After sanding and carefully cleaning the · Appearance in the paint system, e.g. part, it can be coated directly with sinkage or lifting. Standox topcoat or Standox clearcoat. · Elasticity in the paint system. Topcoats and clearcoats should be plasti- · Redissolving when cleaned. cised by adding the respective additives to match the flexibility of the plastic In this case, please note the manufactu- material. rer´s refinishing recommendations. Getting paint to adhere on plastics.

The release agent used to free plastic parts from the mould will also release your paint coating from the plastic. Plastic parts are primarily injection-moulded or reaction injection-moulded with the aid of complex moulds and presses, as well as other highly sophisticated . Very high production rates can be achieved in this way. Release agents are used to ensure that many parts can be taken from one mould without difficulty. Some of these release agents stubbornly adhere to the plastic. Release agents come in three different types and can make life difficult for the refinisher.

External release agents. Internal release agents. Release paints. · Conventional release agents are based Self-release products contained in the Chemically speaking, release paints are a on wax and , dissolved in organic plastics blend are used in what is known polyvinyl alcohol dissolved in water. Such solvents. They can be removed in the as the IMR process. parts are only encountered in negligible bodyshop with suitable organic thin- Zinc stearate is the main chemical con- percentages and are easily identified by ners and a sanding pad. cerned. Parts must be conditioned before the wavy rear. These parts must always being cleaned. Can be cleaned with be cleaned with water first. · Water-thinnable emulsions of release organic solvents or thinners and a sand- Polyvinyl alcohol can only be re- agents are based on wax and oil, i.e. ing pad. moved with water and is insoluble in emulsified in water. These can be organic solvents. removed in the bodyshop with suitable organic thinners and a sanding pad. Water-thinnable release agents cannot be dissolved in water. How to remove release agents from plastic parts.

Conditioning. Cleaning. Conditioning (i.e. warming up) the parts Repeated cleaning is imperative. before they are cleaned can be useful Intensive, repeated cleaning with pad, for the following reasons: brush and fresh is · The heat helps the part “sweat out“ absolutely essential in the bodyshop. release agent (particularly important in the case of PU materials). Simply wiping clean once is rarely suffi- · Stresses in the plastic material are cient, even if the recommended cleaning relieved in order to prevent cracking. agents are used. · Voids (trapped air) can be identified and treated (opened and filled with Textured parts must be cleaned more stopper) BEFORE the part is coated. intensively. Release agents and dirt must be removed from textured plastic If necessary, the parts must be supported parts using a soft brush or high-pressure in order to avoid deformation. cleaner.

After cleaning the plastic parts, it is abso- lutely essential that the cleaning agents evaporate entirely before further process- ing.

14/15 Causes of refinishing flaws.

Mistakes are made everywhere, but knowing where to look cuts down on problems and complaints. Remember that rework costs a lot of time and .

Inadequate preparation (condition- entirely. Standox has developed specially ing, cleaning). tested cleaning products to prevent this Inadequate preparation is the common- happening. est mistake and can have various conse- quences. For example: Applying the coating too soon after · Surface defects due to release agent cleaning. residues. The solvents absorbed by the plastic · Chipping, since the coating is applied material when it is cleaned must be to a release agent which is designed removed completely before the coating to prevent adhesion. is applied, otherwise they will cause a · Cracking if stresses present in the build-up of vapour pressure between 16/17 plastic material are not relieved. the plastic and the coating, ultimately reducing the adhesion. The risk of solvent Any time saved by not conditioning or popping and pinholing is also increased. cleaning a part correctly will often be lost by expensive rework. And this is not counting the loss of goodwill from a complaining customer.

Unsuitable cleaning agents. Highly corrosive cleaning agents can damage plastics such as ABS, PC, PPO, etc., which are not resistant to solvents, and lead to cracks or even destroy them right: Orange peel caused by unsuitable solvent combination.

beneath: Poor adhesion caused by insufficient cleaning or unsuitable adhesion promoters. Unsuitable coupling agents. It has repeatedly been mentioned in the preceding chapters that there are many different plastic materials and that each material has specific properties.

Standox has the experience and the pro- ducts needed not only for refinishing jobs in the bodyshop, but also for high-volume factory finishes, possibly with precisely defined specifications to meet.

Too little plasticiser. Topcoats and clearcoats must contain the right amount of plasticiser. Too little and usually crack under mechanical above: Pinholes are caused when the paint is strain. In any case, please note the applied too soon. Technical Data Sheets.

Tip: The Standothek brochure entitled “Identifying and Eliminating Paint Defects“ provides an overview of the left: Lifting caused by improper isolation most common defects and tips on how and/or through-sanding. to assess and avoid them. Reliable color matching for plastics.

A perfect refinish on plastic components is the result of skilful workmanship, correct preparation and the exact choice of color. Standox offers refinishers many useful aids for precise color matching.

Plastic add-on parts on modern cars are If and when no electronic colorimeter is usually painted in the same color as the available, refinishers may use the color car. In this case, the same color can be information on the Standowin CD or the used with the addition of a plasticiser. color search on the , which is The situation is not that easy when add- accessible via the Standox website of on parts are coated in a different color, each country. Here, they will find special which is often the case on old cars or programs to suggest the right color for- with decorative parts of current models. mulation for each model and the respect- ive add-on parts. In the case of a smooth, glossy surface, Genius and Standowin help refinishers Tip: The Standothek brochure entitled determine exactly the right color shade. “The quick way to a perfect color Based on precise electronic measurement, match“ provides valuable information Standowin will offer the best matching on how to find the right color sheet. color formulation.

18/19 Technical Data Sheets and refinishing systems.

Please contact your Standox representative for the latest Technical Data Sheets and other information on the Standox refinishing systems. The current Data Sheets are also available on the national Standox websites. .standox.com

Standox GmbH · Postfach · D-42271 Wuppertal · D11152147 GB 1007 2750 www