PLEXIGLAS Surface Treatment of
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GUIDELINES FOR WORKSHOP PRACTICE
Surface Treatment of
PLEXIGLAS®
Inhalt
1. General Remarks.......................................................................................................3
1.1 Physical Forms....................................................................................................................................... 3
1.2 Properties and Conditions.......................................................................................................... 3
1.3 Masking Film............................................................................................................................................4
1.4 Scoring and Marking........................................................................................................................4
1.5 Subsequent Surface Protection............................................................................................4
2. Avoidance of Static Discharges........................................................................4
3. Screen Printing..........................................................................................................5
4. Coating.........................................................................................................................6
4.1 Spray Painting.......................................................................................................................................6
4.2 Dip Coating..............................................................................................................................................6
4.3 Curtain Coating...................................................................................................................................6
4.4 RoIler Coating........................................................................................................................................8
5. Matting.........................................................................................................................8
5.1 Mechanical Matting..........................................................................................................................8
5.2 Matting by Thermoforming........................................................................................................9
5.3 Chemical Matting...............................................................................................................................9
6. Stamping and Inscription.................................................................................. 10
7. Surface Dyeing........................................................................................................11
8. Transfer Printing....................................................................................................12
9. Laminating................................................................................................................12
10. Metallizing..............................................................................................................13
10.1 Sputtering in a High Vacuum..............................................................................................13
10.2 Wet Vaporizing, Electroplating, Metal Spraying...............................................13
11. Abrasion-Resistant Coating...........................................................................13
12. Water-Dispersing Coating.............................................................................. 14
13. Cleaning and Care.............................................................................................. 15
13.1 Cleaning................................................................................................................................................. 15
13.2 High-Pressure Cleaning.......................................................................................................... 15
13.3 Removal of Spray Paints and Posters........................................................................ 15
Notes:
In addition to this publication, You can find valuable do-it-yourself These can be obtained from your
there are similar Guidelines for hints on PLEXIGLAS® in: local authorized distributor of
Workshop Practice for professional PLEXIGLAS®.
PLEXIGLAS® fabricators on: Fabricating Tips for PLEXIGLAS®
(Kenn-Nr. 311-5) When using our products,
Machining PLEXIGLAS® please observe
(Kenn-Nr. 311-1) Special leaflets are available on the
properties and fabricating behavior • local building codes and
Forming PLEXIGLAS® as well as the applications of several emissions laws
(Kenn-Nr. 311-2) of our products, for example • applicable standards
• product liability imposed by law
Joining PLEXIGLAS® • multi-skin and corrugated sheets • the guidelines of employers‘ liability
(Kenn-Nr. 311-3) • glazing with solid sheets insurance associations.
• noise barriers
• signage and lighting.
2
1. General Remarks
PLEXIGLAS®, the acrylic (polymethyl • sheets with matte, satin surface on Similarly to bonding, most methods
methacrylate, PMMA) manufactured one side, as well as sheets, tubes of surface treatment require items
by us, can be subjected to various and rods with two matte satin with no or only moderate internal
kinds of surface treatment during surfaces (PLEXIGLAS® Satinice, stress as a result of production tech-
fabrication. This is because of the fa- PLEXIGLAS® Satin Ice, nique or machining. High stress levels
vorable properties of this plastic, e. g. PLEXIGLAS® Crystal Ice). must be eliminated by annealing (see
its perfectly smooth surface. Sur- Guidelines for Workshop Practice,
face treatment normally adds value Combinations of these techniques ‚Machining‘, chapter 8, or
to the finished article and opens up are sometimes also possible. ‚Joining‘, chapter 2.5).
applications for PLEXIGLAS® GS and
PLEXIGLAS® XT® that the untreated 1.1 Physical Forms Prior to surface treatment, the items
base material would be unable to sa- usually need to be cleaned. This can
tisfy. Treatment ranges from decora- PLEXIGLAS® GS is manufactured in be done by blowing down with ionized
tive screen printing to more sophisti- the form of solid sheets, blocks, tubes air or by rinsing with warm water to
cated techniques such as sputtering and rods with smooth or matte, satin which some dishwashing liquid has
in a high vacuum. surfaces (PLEXIGLAS® Satinice). been added. For subsequent dry-
ing, an absorbent, non-linting cloth,
Unlike some other plastics, the PLEXIGLAS® XT is available in stan- e. g. glovelining fabric, should be
surface treatment of PLEXIGLAS® dard and impact-modified grades used. Wiping down with ANTISTATIC
poses very few problems. (PLEXIGLAS® Resist) as smooth, tex- PLASTICS CLEANER may be use-
tured or matte (PLEXIGLAS® Satinice) ful, but this has to be established
PLEXlGLAS® GS is produced by solid sheet, corrugated and multi- from case to case. Certain types
casting, PLEXlGLAS® XT by skin sheet, mirrors, tubes and rods as of surface treatment call for plas-
extrusion. Both types of material well as (EUROPLEX®). tics surfaces that are immaculately
can be surface-treated in nearly the clean. This cannot be guaranteed
same manner. This also applies to Colored PLEXIGLAS® grades are nor- when antistatic cleaners have been
PLEXIGLAS® products for specific mally homogeneously colored. used. Suitable products for cleaning
applications, such as SOUNDSTOP and degreasing prior to surface
(for transparent noise barriers), Whether in standard or special sizes, treatment are THINNER AND CLEA-
or grades with special surfaces. all material packaged on pallets is NER 30/ACRIFIX® TC0030, petroleum
These can have an abrasion- labeled with information for correct ether as well as uncolored absorbent
resistant or mirror coating, or special storage and in-house transport. paper or cloth (washed glove-lining
surfaces such as SATINICE (matte), Generally speaking, PLEXIGLAS® is fabric) soaked with isopropyl alcohol.
HEATSTOP (reflecting solar heat), best stored indoors. All our sheets All agents mentioned are suitable for
or NO DROP (water dispersing). are masked with polyethylene film, short-term use on PLEXIGLAS® GS
which can be disposed of without and PLEXIGLAS® XT.
Differences in machining behavior any problem. In the case of outdoor
are noted in the respective section. storage, effective additional protec- For certain types of surface treat-
tion is required. ment it makes sense to order the
It is the aim of this brochure to help material from your local authorized
you achieve optimal forming results. 1.2 Properties and Conditions distributor with a corresponding note,
If you have any questions about our so that he can perhaps select a spe-
information or the practical work The material behavior of PLEXIGLAS® cial grade which makes the desired
based on it, contact your local au- permits many different types of sur- kind of surface treatment particular-
thorized distributor or our Technical face treatment that are not always ly easy (see chapter 11‚ Abrasion-Re-
Service department. We ourselves possible with other plastics. Owing to sistant Coating‘).
will be grateful for any suggestions its high resistance to chemicals, it is
based on your experience in the field. very versatile in use and, at the same
time, enables partial solvent action
Apart from the techniques discussed in a way that favors a wide variety of
here, which are to be performed by coating techniques.
the fabricators, we ourselves offer
material with upgraded surfaces, e. g. Our leaflets entitled ‚Chemical Resis-
tance of PLEXIGLAS®‘ (Ref. No. 211-
• PLEXIGLAS® and EUROPLEX® PC 2) and ‚Resistance to Stress Cracking
film with abrasion-resistant and Chemical Influences‘ (Ref. No.
coatings, 211-4) provide information on the
• PLEXIGLAS® multi-skin sheets general behavior of PLEXIGLAS® GS
with water-dispersing coatings, and XT towards chemicals.
3
1.3 Masking Film properly removed, and the sheets are in a subsequent operation. Otherwi-
likely to be damaged. se, all materials mentioned – even
Depending on material grade and impact-modified PLEXIGLAS® Resist
thickness, the surfaces of our sheets 1.4 Scoring and Marking – may crack or break under load.
are masked with environmentally
friendly self-adhesive or cling film The environmentally friendly PE 1.5 Subsequent Surface Protection
made from polyethylene. Normally, masking film is intended to protect
the surface masking should remain PLEXIGLAS® sheets during trans- When machined sheets, semifinished
on the sheet until it is in its final port and storage. This protective film or finished parts – but also installed
place. should remain on the heet during all elements – made of PLEXIGLAS®
machining operations, and is best need to be protected against soiling,
If the film must be removed before left on until the finished part is in its chemical or other influences during
surface treatment: hold the sheet final place. further treatment or storage –
firmly down on one side and strip off e. g. for renovation purposes –
the film with one quick movement of Marking out of drill holes, contours or the following measures can be
the hand. edges to be cut off is therefore done recommended:
on the masking film. If the latter has
When sheets are exposed to the already been removed, use special • coatings applied in liquid form;
weather, the masking films must be pencils (e. g. soft lead or grease pen- which can later be stripped off as
removed within four weeks, regard- cils) for marking out directly on the films (such as 30 % aqueous solu-
less of their adhesive properties, sheet surface. tions of PVAL) or protective films
since polyethylene may become • compatible adhesive crêpe tapes
brittle after this period of time or Scribers or prick punches should not adhesive polyethylene films or
adhere even more strongly. In eit- be used unless it is ensured that the polyethylene bags, which are then
her case the films can no longer be notches they cause are eliminated closed or heat-sealed.
2. Avoidance of
Static Charges
Owing to their excellent insulating hundred volts high and cannot be Very often, however, it is better to
properties, most plastics, including dissipated unless the surface comes use an antistatic cleaner (see ‚13
PLEXIGLAS® GS and XT, show high into contact with another conductive Cleaning and Care‘).
surface and volume resistivity. As a or reversely charged material, whe-
result, they may become statically reupon flashover occurs. The effectiveness of antistatic treat-
charged with the associated nega- ment is inversely proportional to the
tive effects of dust attraction and The ability to become statically volatility of the active substances
(rarely) flashover. Static charges may charged can be eliminated by ap- contained in the product: the lower
build up due to: plying surface layers that contain the friction, the higher the atmos-
moisture-binding electrolytes or by pheric humidity, the lower the room
• m
echanical friction in contact adding electrolytes to the polymer temperature and the less dust there
with solid objects, cloths or formulation. The latter is not recom- is around, the longer the antistatic
polishing agents; mended for acrylics, though, since effect will last.
• friction produced by dry air the doses required to produce an an-
currents, for example; tistatic effect change the properties Another very economical method is
• removal of the masking film of these polymers, e. g. their optical blowing the sheet or parts of it down
from the sheet. appearance, so very noticeably that with ionized air. The effect, however,
the final product becomes unsuitable is of fairly short duration, e. g. just
Static charging upon removal of the for most applications. long enough for the next work step to
masking film, for example, causes an be performed.
electron surplus on one sheet surface As mentioned further above, it is
and electron deficiency on the other. common practice to treat the sur-
The charge may, however, vary on the faces of PLEXIGLAS® GS and XT
same surface of a sheet or finished with antistatic substances as a pre-
item. In the case of electrically insu- ventive measure, or else to eliminate
lating plastics, this difference will not the charges once they have built up.
balance itself. The charges - nega- Rinsing with water is the simplest
tive or positive - are up to several form of external antistatic treatment.
4
3. Screen Printing
Screen printing is the best-known vered with a light-sensitive layer and contours are drawn on a formed part,
method for decorating large runs of exposed to light through a positive. preferably made of PLEXIGLAS® GS,
PLEXIGLAS®. It permits reproduction The exposed areas cure, the unexpo- which is then heated and restored to
of the most intricate details of com- sed ones can be washed out. its original flat state. The distorted
plex motifs. image corresponds to the stencil to
For multi-color printing, one mesh be made (distortion printing).
Screen-printed sheets can be stencil is needed for each color. Lay
thermoformed at the appropriate marks at their edges ensure that the For screen-printing PLEXIGLAS®, use
temperatures without damaging the differently colored areas are clearly inks that do not cause stress cra-
print. That enables raised patterns defined. Before the next printing step cking in acrylics, but adhere well
or three-dimensional moldings to be is performed, the previously applied enough for the application. The
produced from screen-printed flat ink has to be sufficiently dry. instructions of the ink manufactur-
sheets. ers should be observed, as they offer
Subsequent spray coating with a clear different products for different types
Most important in this context is protective varnish improves the wea- of plastics.
the heating method: Whereas oven ther resistance of the print. Alterna-
heating normally ensures a uniform tively, the print may be applied to the The solvents contained in the inks
degree of stretching, IR radiators back of cut-to-size sections of trans- are likely to have an adverse influ-
involve the risk of irregular heating of parent, UV-absorbing PLEXIGLAS® ence on the plastics surface. There-
multi-colored parts, thereby distur- grades, where it is protected against fore it may be advisable in some
bing the thermoforming process. climatic influences and mechanical cases to anneal the parts prior to
stress (see also Chapter 4.1). screen printing (see Guidelines for
In order to avoid distortion of the Workshop Practice, ‚Machining‘,
printed pattern, certain areas may be After the printing process, stencil and chapter 8, or ‚Joining‘, chapter 2.5).
covered while heating the remainder squeegee should be carefully cleaned
of the sheet with IR radiators. with cleaning agents or paint thin- If screen-printed parts are to be
ners recommended by the ink ma- area-bonded with polymerizati-
Screen printing may be performed by nufacturers. Depending on the type on adhesives such as ACRIFIX®
hand or screen printing machin e for of ink used, the printed items are left 190/2R0190, for example, special
larger runs (see Fig. 1). to dry at room temperature or above crosslinked color lakes are to be used
(approx. 60 °C). that withstand the solvents con-
The sheet to be printed is placed on tained in this adhesive. Area bonds
a table, fastened with clamps or by Screen-printed parts that are to are described in our Guidelines for
means of a suction plate. A squeegee be thermoformed require a stencil Workshop Practice ‚Joining‘, chapter
is used to press the ink through a that allows for the distortion caused 2.7 Bonding Techniques.
porous screen made of fabric tightly by forming. To this end, the desired
stretched in a frame and a mesh
stencil with the photochemically ap-
plied negative of the printing pattern.
The distance between the underside
of the stencil and the sheet surface
must be such that the image area
touches the screen only at those
points across which the squeegee
is drawn. This distance is usually bet- Figure 1: Principle of screen printing
ween 5 and 10 mm, depending on the 1 = stencil, 2 = screen, 3 = frame,
4 = PLEXIGLAS®, 5 = worktop, 6 = squeegee
size of the stencil.
The mesh stencil consists of a frame
holding a stretched polyamide or po-
lyester fabric with 80 to 140 threads
per cm and the stencil proper. For
coarse substrates or rich multi-color
printing a coarse mesh is used, and
a fine mesh for sharp contours and
intricate details. Figure 2: Screen printing frame
a = Sections of different frames,
b = Size of screen printing frame (1)
The stencil proper is normally prepa-
as compared with surface to be printed (2)
red photochemically: the mesh is co-
5
4. Color Coating
Coating is the second most widely Constant temperatures between 18 When treating clear-transparent
used method of surface treatment and 25 °C are an essential prerequi- PLEXIGLAS® sheets – the second
and many of the details to be borne site for maintaining the viscosity of option – the coating can be ap-
in mind have already been mentioned the coating systems at the same plied on the back of the sheet for
in connection with screen printing. level for all processes and for avoi- improved weather resistance. This
Thus, the workpieces to be coated ding condensate formation. While the requires an additional paint coat, e. g.
need to be carefully cleaned and relative humidity should not be high- to provide logos or symbols with a
treated with an antistatic where ne- er than 60 %, an adequate supply of (colored) background or base coat
cessary (see chapter 1.2). Annealing fresh air is to be ensured. (see Fig. 7).
to relieve internal stress may also be
required (see Guidelines for Work- The paint and the clean workpiece 4.2 Dip Coating
shop Practice ‚Machining‘, chapter 8, should be taken to the workroom in
or ‚Joining‘, chapter 2.5). good time so as to acquire the same Dip coating is often the method of
temperature before painting choice for priming or for applying
4.1 Spray Painting is started. protective coatings. Thus, PLEXIGLAS®
can be coated with masking lacquers
Spray painting is equally suitable for Just as there are special inks for prior to spray painting or metallized
individual items and large runs. The screen printing, there are special surfaces can be protected with clear-
paint loss is usually higher than in paints for spray painting. The major transparent or transparent colored
screen printing, but can be limited requirement is that they adhere well coatings. For dip coating, the workpiece
by the choice of nozzle and spraying to PLEXIGLAS® GS and XT, are easy is completely or partially immersed in
technique. The spray gun atomizes to process, compatible with PMMA, the paint bath. This enables all-round
the paint and deposits it on the sur- weather-resistant and formable coating in one step (see Fig. 8).
face to be painted (See Figs. 3 and along with the substrate.
4). Using stencils or masking lac- The layer thickness usually varies
quers, it is possible to paint certain Areas not to be painted or to be according to the consistency of the
areas only or to apply symbols and painted in different colors are co- coating system or its solids content.
lettering. vered with stencils, adhesive film or Moreover, the jig required for all-round
removable masking lacquers. The coating causes some flaws. In order to
latter are applied by brush or spray increase the layer thickness it may be
gun. When they are dry, the contours necessary to dip the workpiece several
are marked on them, or the film, by times and let it dry in between.
means of a fine scoring knife, and
the areas to be painted are laid open. Drying is performed with IR radiators or
Please bear in mind that scoring may by means of warm air. It should be as
have a notch effect. Stencils must be forceful as possible in order to prevent
firmly secured and should be cleaned the paint from running down too quickly
at regular intervals. Once painting on vertical surfaces, thereby forming
and drying are completed, remove socalled sags.
the remaining bits of lacquer or film.
4.3 Flow Coating
Figure 3: In some cases, the masking film
Position of spray gun in relation to workpiece applied to our sheets for protection Flow coating is best suited for coa-
1 = spray gun, 2 = PLEXIGLAS®
during transport may replace the ting large, even surfaces of PLEXI-
stencil or adhesive film, provided it GLAS®. Very uniform layer thicknes-
The walls and floors of the workroom still adheres well enough. There are ses are achieved by this process,
must be solvent-resistant and easy two alternative ways to build up a which is necessary to get a uniform
to clean. The spray booth (see Fig. paint coat: color impression with large, trans-
5) should be provided with a water parent colored or translucent items.
curtain and an extractor that at least In the majority of cases, paint coats Flow coating is thus mainly used for
complies with environmental regula- are applied to translucent or opaque applying base and top coats to illu-
tions. colored sheets of PLEXIGLAS®. The minated advertising signs and for the
coated side is normally the one ex- manufacture of projection screens.
Explosion-proof electrical instal- posed to the weather and mechani-
lations and luminaires are a must. cal stress. A clear varnish The flow coating machines available
Otherwise the guidelines of the offers additional protection. in the market operate more or less by
employers’ liability insurance associ- the same principle (see Fig. 9). The
ation are to be observed. differences are mainly in design and
in the accessory equipment offered.
6
Because of the high coating speeds,
this technique is particularly suitable a) = from
for large production runs. the front:
1 = 1st spray pass,
2 = 2nd spray pass
Generally speaking, the coating
systems are the same as for spray b) = from the side:
painting, but the required viscosities overlapping of
are normally different. It is important zigzag movements
to choose systems that are compa-
tible with PLEXIGLAS® and satisfy
the special requirements of the envi- Figure 4: Guiding the spray gun in crisscross fashion
saged application.
Processing and post-treatment are
to be performed according to the
manufacturers’ recommendations.
The general advice given in the pre- 1 = work table,
vious chapters also applies here. 2 = water curtain,
3 = extractor
Figure 5: Schematic of a spray booth
Figure 6:
Buildup of a paint coat on the front
1 = PLEXIGLAS®, e. g. homogeneously
colored in yellow
2 = symbol (K), e. g. red paint
3 = clear protective varnish 1 = PLEXIGLAS® part, 2 = paint trough,
4 = weather side 3 = conveyor unit, 4 = drying section
Figure 8: Schematic of a semi-automatic dip coating line
1 = PLEXIGLAS® section,
2 = paint feeder,
3 = paint,
4 = adjustable gate,
5 = coating layer,
6 = overflow trough,
7 = conveyor belt,
Figure 7: 8 = from pump,
Buildup of a paint coat on the back 9 = to pump
1 = PLEXIGLAS®, Clear
2 = symbol (K), e. g. red paint
3 = base coat (background), e. g. yellow paint
4 = clear protective varnish
5 = weather side Figure 9: Principle of flow coating
7
Figure 10:
Principle of roller coating
1 = roll,
2 = coating film,
3 = PLEXIGLAS® advertising sign,
4 = spacer rail
4.4 Roller Coating cess, the workpiece must be cleaned, The roller has an elastic, wettable
degreased and dried. cover - usually made of finegrained
Roller coating is widely used for rubber - whose hardness (approx.
workpieces made of PLEXIGLAS® with For roller coating, the paint is first Shore A 45) should be adjusted to that
raised or sunken designs, e. g. adver- spread evenly on a smooth and level of the surfaces to be coated. The more
tising signs with logos or emblems. It surface and is then taken up by the clearly defined the contours and the
is also suitable for applying opaque roller. The paint-soaked or moistened smoother the surfaces, the harder the
base coats or clear protective coa- roller - guided by spacer rails on both rubber may be.
tings, for the manufacture of liquid sides - is carefully passed over the
film maskings and lettering applied by workpiece. In the case of raised pat- Important for perfect coating is the
template. Small production runs can be terns (reliefs) this ensures that only the right viscosity of the paint and ade-
roller-coated manually with satisfac- projecting surfaces are coated (see quate drying time.
tory results. Before starting the pro- Fig. 10).
5. Matting
PLEXIGLAS® is available in a number gloss and textured. Mechanical Another feasible matting technique
of clear, white and colored grades treatment, in particular of dark-colo- is sanding with emery paper or eme-
with smooth, textured or matte red material, may produce a grayish ry cloth. We recommend wet sanding
surfaces. The latter family of grades, tinge, which is least noticeable with in order to generate a minimum of
PLEXIGLAS® Satinice, offer highly white material. stress within the sheet or formed
attractive options all from one sour- article. The textures produced show
ce to designers and fabricators: cast 5.1 Mechanical Matting the preferred direction of sanding.
Satinice SC with one satin surface Since they are never perfectly regu-
and DC with two satin surfaces, In sandblasting, a stream of – usually lar, sanding is usually only performed
extruded PLEXIGLAS® Gallery AR – quartz sand, corundum or alumi- on surfaces of minor importance or,
with an antireflective effect on one num oxide strikes the surfaces to be on the contrary, where precisely this
side, and the PLEXIGLAS® Satin Ice matted at high speed. The degree of kind of texture is desired.
grade with two matte surfaces and abrasion or matting depends on the
the highest light diffusion. Apart impact velocity as well as the particle For further details on sanding, ab-
from sheet material, tubes are also size and shape of the material used. rasives and grits to be used, see our
available in PLEXIGLAS® Satin Ice. Guidelines for Workshop Practice,
Since these grades offer a very Large areas are best treated by ‘Machining’, chapter 7.1.
uniform matte effect that is suitab- machine, since matting by hand is
le for many applications, this range often irregular. Partial matting is also Matte surfaces can also be produced
dispenses with processing costs for possible if the areas to remain glossy on PLEXIGLAS® by means of rotating
subsequent matting. are covered with stencils or self- brushes. Their bristles are made of
adhesive film. steel or brass, or else of plastics such
Subsequent matting of PLEXIGLAS® as polyamide fibers. Round brushes
surfaces is, of course, also possible. While sandblasting produces good fitted with strips of emery cloth, so-
Several mechanical, thermal and matte effects, the surfaces thus tre- called flap wheels, are also widely used.
chemical processes are known that ated are sensitive to touch, i. e. may
allow you to achieve any desired change in appearance as a result of
degree of matteness between high fingerprints or dirt pickup.
8
Figure 11: Mechanical matting with an orbital sander
1 = PLEXIGLAS®,
2 = foam,
3 = rubber blanket,
4 = compressed air
Figure 12: Schematic of blow molding of a light dome with matte interior surface
5.2 Matting by Thermoforming If the above-mentioned materials not recommended. The matte effect
are heated, or at least conditioned, is mostly irregular, stress cracking
PLEXIGLAS® XT and to a limited this normally enhances the matte may occur and handling in general
extent also PLEXIGLAS® GS can be effect. Especially heatconducting involves certain risks.
matted by thermoforming. To this materials such as aluminum and
end, the sheets are heated to for- steel should therefore be heated to Solvents should only be used for pro-
ming temperature and placed over the thermoforming temperature of ducing a satin finish after sanding. To
molds with matte surfaces which are the material to be matted, i. e. to a this end, the surface is first treated
reproduced on the sheets. minimum of 80 °C for PLEXIGLAS®. with coarse-grit paper, by hand or
on the belt sander and is then wiped
The following techniques are possi- PLEXIGLAS® can also be partially down with a cloth (rolled into a ball)
ble (mentioned in order of increasing matted in this way, in which case soaked in methylene chloride (di-
technical outlay): a pattern, logo or part cut out of a chloromethane).
sheet is placed on the mold.
• forming on soft foam, e. g. polyether Care must be taken to wipe in the
or polyurethane; Compared with mechanical matting, direction of sanding. In the case of
• forming on ROHACELL® rigid foam, matting by thermoforming provides PLEXIGLAS® GS Black 811/9H01,
• forming on dull material surfaces, surfaces that are less sensitive to for example, this produces an ebony
e. g. sandpaper, textile fabrics, non- touch. Moreover, even free-blown sheen (see Fig. 13).
wovens, glassfiber mats, wood or items can be matted in this way (see
matted plastics; (a PLEXIGLAS SA- Fig. 12), provided the degree of stret-
TINICE® SC or DC surface can, for ching is not too high.
example, be reproduced on (briefly)
thermoformed PLEXIGLAS® XT 5.3 Chemical Matting
moldings).
• forming on metal surfaces, i. e. Matting with chemical substances
sandblasted, etched or ground sur- such as solvents and acids, which
faces of steel or aluminum. work on or attack acrylic surfaces, is
9
6. Stamping and Inscription
The techniques employed for inscri- characters or motifs. Apart from ble contours. Approx. 2 to 3 seconds
bing plastics surfaces are so diverse special laser inscription units, the at 150 °C are normally sufficient.
and so well-known that they do not CO2 lasers employed for cutting
need to be described in further detail PLEXIGLAS® sheets can also be used We recommend you to determine the
here. Only a brief presentation of the for this purpose to a limited extent required stamping time by preliminary
techniques relevant to PLEXIGLAS® (and with reduced performance. tests under actual conditions and to
is therefore given. look out for a possible notch effect.
The advantages of this type of
Apart from the most simple direct inscription similar to engraving are The process can be performed
(usually manual) means of inscri- that it is rapid, abrasion-resistant manually with the aid of brass dies
bing PLEXIGLAS® with pencils (see and dispenses with paints or printing inserted in soldering irons (see Fig.
Chapter 1.4), the best-known indirect inks. However, it also means that no 14), or else in a press. The die tempe-
method is to apply stickers (labels colored laser inscriptions are possi- rature should be adjustable and be
etc.) to the material. These are nor- ble, only light/dark contrasts of the controlled by temperature sensors, if
mally printed or inscribed, or are left given grade of PLEXIGLAS®. necessary.
blank for subsequent information to
be included on the PLEXIGLAS® part. Photochemical etching offers a spe- The principle of color embossing is
cial kind of inscription or the trans- the same as that of blind embossing,
fer of photographic motifs to the with the additional feature that the
surface of films rather than sheets of impressed symbols are lined with
PLEXIGLAS®. colored foil or metal leaf. The latter
consists of a carrier and a paint or
No further details of this copying metal coat with adhesion promoter.
technique for plastics films are given Die heat and pressure cause the
here because the processing inst- color to be transferred to the work-
ructions of the manufacturers of the piece (see Fig. 15). The die tempera-
required chemicals must be closely ture depends on the type of foil or
followed. leaf but is generally between 70 and
100 °C for PLEXIGLAS®. These rather
Figure 13: Chemical treatment of a The embossing of PLEXIGLAS® low temperatures limit the penetrati-
previously sanded surface means the impression of scripts, on depth of the die.
symbols etc. by means of a heated
Lettering and motifs are often die. A distinction is made between For large runs, stamping presses with
applied to large runs of cut-to-size blind embossing (hot stamping) and automatic roller feed are used. They
sheets and moldings with round or color embossing. Both techniques consume a minimum of foil and ope-
slightly spherical surfaces by tampon mainly serve for marking, lettering or rate at high speeds. Moreover, several
printing. The parts pass through the decoration. colors can be produced at the same
printing machine, where an elas- time.
tic ball of textile or plastic material For blind embossing, the die is
(tampon) picks up a pre-printed heated to forming temperature and To help fabricators to select the ap-
inscription from the printing unit and pressed into the cool material. The propriate inscription method, the ta-
transfers it individually to the parts shape of the die is reproduced in the ble in Figure 16 provides an overview
in question. workpiece as a sunken ‘engraving.’ of the pros and cons of the various
techniques.
For large series of mainly flat parts Stamping should not take too long in
(or endless films), ink jet printing order to achieve the sharpest possi-
offers the advantage of being able
to change texts fairly quickly by
means of digital programming. This a) = manually performed
technique is used less for decorati- stamping
ve or advertising purposes, more for 1 = soldering iron shaft, hot;
technical statements (see marking of 2 = brass die with raised types;
3 = PLEXIGLAS®
PLEXIGLAS® grades on the protecti-
ve masking film). b) = stamped relief
inscription
Laser printing operates in a similar
way, but allows much more individual
inscription via PC control and with
resolutions up to the most minute Figure 14: Hot stamping on PLEXIGLAS®
107. Surface Dyeing
Aqueous dye solutions are used for
coloring the surfaces of – predomi-
nantly – transparent parts made of
PLEXIGLAS® GS and XT. The swelling
agents they contain, e. g. acetone, act
at high temperatures. The process is
suitable for small finished items of
cut-to-size sheets of up to approx.
200 x 100 mm, which are immersed
in the heated dye bath. Transparent
colors show only limited resistance to
light and weathering.
Machining and polishing of the items
to be colored must be completed
beforehand. They are placed in a
warm aqueous bath to which a mild
cleaning agent has been added,
are thoroughly cleaned, degrea-
sed, rinsed with distilled water and
dried. Annealing prior to dyeing is
recommended (see our Guidelines Figure 15: Color embossing of PLEXIGLAS®
for Workshop Practice ‘Machining’,
chapter 8, or ‘Joining’, chapter 2.5).
Inscription Special surface dyes and formulati-
Laser Inkjet Tampon Stam- Label
ons are to be used, depending on the
ping given technique.
Capital expenditure • + - + +
Shades may vary from pale to rich,
Operating costs + • • + + depending on how long the items are
Quality of inscription + + + + +
immersed in the dye solution. Uni-
form coloring is achieved by with-
Abrasion resistance + • • + • drawing the item slowly and carefully
Permanent resistance + • - + - from a thoroughly stirred bath in
which it was totally submersed.
Micro-inscription + • • • -
Inscription rate + + • • + Moreover, the temperature of the
Inscription of curved/matte surfaces + + • + -
paint bath must be carefully moni-
tored. Tests with smaller pieces are
Inscription of “contaminated” surfaces + - - + -
recommended. After the dyeing pro-
Accuracy of position + + • • • cess, the workpiece is rinsed briefly
with warm water, dried and placed in
Reliability/availability of system + • • + +
the oven for several hours at 70 °C to
Insensitivity to touch + + - - - eliminate solvent and water residues.
Integration into CIM environments + + - - •
Freedom from paints/solvents + • • + +
Flexibility (“batch size 1”) + + • • •
Choice of printing colors - • + + +
Figure 16: Comparison of Inscription Techniques
+ = highly suitable • = suitable - = limited suitability or unsuitable
(Source: A. Schulman GmbH, Kerpen, in PLASTVERARBEITER, 51st year, 2000, No. 12)
118. Transfer Printing
Transfer printing is the method by After placing the paper on the sheet, period, the more pronounced the loss
which a single- or multi-colored the press is closed and its heated of brilliance. The thickness tolerance
pattern is transferred from a carri- platens are brought into close contact of the sheet and the accuracy of the
er – usually transfer paper – to a flat with the paper-covered sheet. The press also play a part in this context.
item to be decorated. Printing occurs printed paper quickly reaches tempe-
at high temperatures, so that the ratures between 150 and 250 °C, the Against this background a process
dyestuff migrates from the carri- inks change from solid to gaseous and variant* was developed that permits
er to the item to be decorated and penetrate deep into the sheet to be printing of developable surfaces, i. e.
penetrates into it. The advantages printed. The penetration depth de- surfaces that can be rolled out flat
of the process are the great variety pends on the temperature, the type of without distortion, such as cylinders
of possible printing patterns and the ink used and the transfer period. or cones. Moreover, curved plastic sur-
extremely precise reproduction of even faces of any desired configuration can
the finest details. This is particularly With PLEXIGLAS®, transfer may take be partially printed and, finally, distor-
so if gravure-printed paper is used, up to 10 minutes. The pressure need ted prints for subsequent thermofor-
but offset- and screen-printed paper not be very high, i. e. just high enough ming are also possible.
also produces good results. Transfer to ensure good contact between
printing is a fairly simple process but transfer paper and PLEXIGLAS® sheet The newly developed “digital trans-
nevertheless requires some experience without distorting the latter. fer printing” offers the PLEXIGLAS®
and technical know-how. fabricator a more economic access
This printing technique does have a to this printing technique: quickly on
In the process, a sheet of PLEXIGLAS® disadvantage, however: even if all due PC generated designs can be printed
GS or XT is placed in a heatable press. care is taken, residues of paper or directly onto transfer paper and thus
The printed paper – colored side release agent usually remain on the transferred to PLEXIGLAS® parts in a
facing the material – is placed on the sheet surface or leave imprints. cost-saving manner.
sheet, carefully avoiding any creases.
If necessary, a heatresistant release This impairs the otherwise outstan- *) European Patent EP-B 1102 20
agent can be applied between the ding surface gloss of PLEXIGLAS®. The of Röhm GmbH
paper and the sheet to ensure neat higher the transfer temperature and
separation after printing. pressure and the longer the transfer
9. Laminating
The term laminating denotes the cause partial detachment of the For laminating large areas, use a
application of, mainly, films for de- laminating film. roller stack in order to avoid air ent-
coration, lettering, identification, re- rapment and to achieve the neces-
inforcement (e. g. protection against Where large areas are to be laminated sary contact pressure for optically
splinters) or subsequent tinting (pro- durably and aesthetically, it is there- flawless application.
tection against sunlight) to workpi- fore recommended that the cut-to-
eces of PLEXIGLAS® GS and XT. size sheets or workpieces be dried for Laminating with non-adhesive film is
several hours in an airflow oven at 70 slightly more difficult. Depending on
Films can only be applied to flat, to 80 °C prior to laminating. the material used, special pretreat-
cylindrical or slightly curved surfaces. ment may be required. Thus, for exa-
They can normally not be thermofor- Pointwise or partial detachment of the mple, certain films are activated with
med together with PLEXIGLAS®. film may, however, also be caused by water on their laminating surface
dust particles from the air which settle and can then be applied by means of
When selecting the films, adhesive between the sheet and the film. a blade.
labels or decals, it must be ensured
that they do not cause stress cra- Self-adhesive films should be rolled Decals for labelling, lettering or de-
cking in acrylics. This may be the on without entrapping air bubbles or corating are often used in combinati-
result of plasticizers migrating from else applied to the sheet by means of on with screen printing or protective
plastics films or attack by solvents a soft cloth. When laminating by hand, spray coating.et.
contained in adhesives. stripping off the masking paper and
applying the film should be performed
Since acrylics are gas-permeable, gradually, because otherwise the film
exhalation from the substrate may would be very difficult to handle.
1210. Metallizing
The smooth glossy surfaces of surface quality of the workpiece. however, be curved cylindrically while
PLEXIGLAS® readily accept immacu- Therefore, care must be taken to cold, and to a limited extent even
late metal coats. Metallizing is above choose injection molds with well-po- spherically if they are mounted in a
all used for providing optical devices lished walls. Sheets or molded items round frame.
with mirror coats or barrier layers, must not be cracked or damaged.
but also for decorative purposes. Depending on the intended use, the 10.2 Wet Metallizing, Electroplating,
Since PLEXIGLAS® is electrically metal layer thickness is between 0.1 Metal Spraying
insulating, electrodeposition is nor- und 0.5 µm; in special cases up to
mally not possible. 1 µm. A coherent metal coat forms Two methods are available for wet
at approx. 0.2 µm, below this value metallizing: chemical metallizing and
10.1 Sputtering in a High Vacuum so-called semipermeable mirrors are silver-spray technique. Since chemi-
obtained. cal metallizing is not yet fully explo-
Sputtering requires some experience red, it should not be used. The silver-
and should only be performed by The essential prerequisite for suc- spray technique can also be ignored,
specialists who also own the ne- cessful sputtering is an immaculate- since it requires a considerable
cessary equipment. Only the basic ly clean substrate surface. This has technical outlay and the adhesion of
principles of this type of surface to be borne in mind when ordering the metal coat is usually very poor.
treatment will be discussed here. the sheets or when pretreating
formed parts. In order to protect the Generally speaking, PLEXIGLAS® is
As long as it is not finished work- vapor-deposited layer from mecha- suitable for electroplating. Apart
pieces that have to be metallized, nical damage, an additional coating from requiring extensive knowledge
PLEXIGLAS® XT Mirror sheets can be is usually applied: clear-transparent and experience, however, this tech-
used instead. on the front of the PLEXIGLAS® nique is of minor importance for
workpiece and possibly opaque on its electrically insulating materials such
In a special vacuum chamber, the back. Suitable application methods as PMMA. It should only be perfor-
metal to be applied - usually lowmel- are spraying, dipping or flow coating. med by specialists.
ting aluminum - is heated to evapo-
ration temperature. The condensing Subsequent forming of sputtered Although metal spraying (also
vapors cause the desired metal sheets of PLEXIGLAS® or PLEXI- known as plasma or arc spraying)
deposition on the PLEXIGLAS® parts. GLAS® XT MIRROR by conventional is performed in the plastics indus-
techniques is impossible since the try, it has only rarely been used for
The gloss and smoothness of the metal coat cracks when exposed PLEXIGLAS®.
sputtered part depend on the original to heat. The metallized parts can,
11. Abrasion-Resistant
Coating
We offer abrasion resistant-coated The parts to be coated should lend The high demands placed on surface
PLEXIGLAS® and EUROPLEX® sheets themselves easily to the process: quality are easiest to satisfy with
and films in varying quantities, changes in cross-section should be flat or only slightly formed parts, (e. g.
depending on demand. Specialized smooth; there should be no sharp automobile side windows made from
companies exist that have expe- contours, drill holes or recesses in PLEXIGLAS RESIST®) that are clea-
rience in providing sheets, blocks, order to avoid paint runs or paint ned automatically and then dip- or
tubes etc. as well as finished parts buildup and other optical flaws. flowcoated.
made from our products with abrasi-
on-resistant coatings. Ejector lugs, sprues and manifolds on The prerequisites for perfect surface
molded items may be used as means coating are filtered coating systems,
Optimum results can be guaranteed of suspension. This aspect should be carefully cleaned substrates and
if the coating systems are specially taken into account when designing performance of the coating process
adjusted to the particular product. the mold or molding. under cleanroom conditions in the
This should be clarified in talks with appropriate climate. Such strin-
the fabricator who will perform the Suitable coating techniques are dip, gent requirements make sense if we
abrasion-resistant coating process. flow or spray coating. consider that the final thickness of
13the coating is approximately 8 µm, thickness exceeds 10 µm and the and impact stress. What is deter-
so that even minor impurities or dust substrate is impact-modified. Coa- mined is the increase in haze of the
particles will inevitably cause flaws. tings based on melamine resin with coated parts after treatment accor-
a strain at break of 7 % do not show ding to these test methods:
It takes several hours of stoving at this effect.
around 80 °C for the coatings to be (a) Taber Abraser test to ISO 9352
fully cured. The higher the tempe- Both abrasion-resistant coating for frictional stress (e. g. during
ratures that can be adjusted (which systems improve the resistance to cleaning)
naturally depends on the softening chemicals, particularly to short-term
temperature of the substrate and the exposure to acids, alkalis and organic (b) Falling Abrasive test to
degree of shaping of moldings), the solvents. DIN 52348 for impact stress
shorter the required curing times. (e. g. sand entrained in head wind
Parts with a polysiloxane coating impinging on helmet visor).
The mechanical and thermal proper- cannot be thermoformed, but cold
ties of parts with abrasionresistant curving is possible. The bending The machining behavior of abrasion-
coatings are more or less the same radius is 330 x sheet thickness. The resistant coated PLEXIGLAS® ele-
as those of the uncoated substra- surfaces can be printed under certain ments is slightly different to that of
tes. Given certain types of stress, conditions, but coloring is not pos- uncoated material. Whereas sawing,
however, the influence of the coating sible. drilling, milling and edge polishing of
becomes very noticeable. sheets and formed parts are per-
The flexible melamine top coat can formed as usual, the surface with
Coatings based on polysiloxane have be cold-curved with subsequent hot its hard crosslinked top coat cannot
a strain at break of 1.2 %. Strains relaxation (application: visors for be polished; but this should not be
beyond this value cause cracking in crash helmets). This coat can also be necessary anyway. Nor can it be
the coating. Abrupt flexural stress printed and embossed/cut. bonded using the normal adhesives
results in crack propagation into the for acrylics.
substrate. Particular attention has In assessing abrasion resistance, a
to be paid to this effect if the layer distinction is made between friction
12. Water-Dispersing
Coating
Water that settles or condenses on positive material properties. In fact, surface of PLEXIGLAS® SP always
acrylics is likely to form droplets. Whe- it enhances the transparency and faces inwards. In patio/conservatory
reas this is no disadvantage for the speeds up drying. roofs, on the other hand, it should face
majority of applications, in others a outwards (upwards). Rainwater then
clear view must be preserved indepen- As opposed to subsequent application runs off as a film and the surface dries
dently of the weather (e. g. transparent of a water-dispersing agent, the more quickly. Stains and water marks
noise barriers made with PLEXIGLAS NO DROP coating applied to are largely avoided and the pleasant
SOUNDSTOP®), or droplet formation PLEXIGLAS® products at our factory appearance and transparency are
on the interior surfaces of heat- – or the all-round Alltop coating on maintained. In order to safely prevent
nsulating multi-skin sheets of some PLEXIGLAS® multi-skin sheets steaming up of crash helmet visors
PLEXIGLAS® is undesirable (e. g. under – offers the additional benefit of being made of EUROPLEX® or PLEXIGLAS
patio/conservatory roofs and green- weather-resistant and insoluble in RESIST®, for example, an antifogging
houses) as it reduces the light trans- water and therefore not having to be agent can be subsequently applied.
mission and involves the risk of water renewed from time to time.
dripping down and damaging the
crops. The water-dispersing effect is achie-
ved by increasing the solid-state
A water-dispersing coating, i. e. one surface tension over that of water.
which forms a water film, eliminates As a result, care must be taken in
this drawback without affecting the greenhouses that the NO DROP
1413. Cleaning and Care
Plastics normally become statically Should there ever be scratches on a For PLEXIGLAS® parts with an abrasi-
charged and attract dust as a result. sheet of PLEXIGLAS®, these can be on-resistant polysiloxane coating, you
Out of doors this is usually prevented eliminated from the smooth surface may use VANDAL-EX. Pretreatment
by air and moisture, whereas in closed without any problem. Treat the scrat- with paint-repellent substances is not
rooms this phenomenon is promoted ched area first with wet sandpaper of, recommended for acrylics.
by mechanical friction at the plastics say, grit 240, and then go over it with
surfaces, air currents and dry air. 400- to 600-grit paper. Finally polish Posters should be thoroughly soaked
the sheet with a soft cloth and with water and some dishwashing
For this reason, slightly soiled mate- ACRYLIC POLISHING PASTE or com- agent for about 10 minutes, whereu-
rial should be treated immediately mercially available car polish, or else pon they can be removed with ease.
(heavily soiled material after thorough use a buffing wheel and polishing wax. We advise against pretreatment with
cleaning) with an antistatic agent, poster-repellent products as these
e. g. Burnus ANTISTATIC PLASTICS 13.2 High-Pressure Cleaning impair the appearance of the PLEXI-
CLEANER, which should be sprayed GLAS® surface.
on and distributed with a soft cloth Large glazed areas or facades are
without wiping the surface dry. The often cleaned mechanically, using
dust-repellent effect is then retained rotating brushes, squeegees and the
for a prolonged period of time. like. No such methods are suitable for
PLEXIGLAS®: Even if brushes are used
Subsequent polishing of stressed sur- with copious amounts of water, there
faces (especially of PLEXIGLAS®) can is no way to exclude scratching of the
be performed easily and effectively sheet surfaces.
using the right cleaning and polishing
agents. Windows and other exposed On the other hand, outward-facing
glazing areas may be cleaned by me- PLEXIGLAS® surfaces can convenient-
ans of a highpressure spray-cleaning ly be cleaned with high-pressure/hot-
unit, possibly with some dishwashing water cleaning units. The recommen-
liquid in the water. ded pressure is 50 to 100 bar and the
water temperature should be between
13.1 Cleaning 50 and 80 °C. Via the integrated do-
sing unit, approx. 1 to 3 % of a mode-
Dirt can hardly cling to the smooth rately foaming cleaning concentrate
surfaces of PLEXIGLAS®. Dust is remo- should be added to the washwater, e. g.
ved with water and some dishwashing BURLANA® by Burnus.
liquid, using a soft, non-linting cloth or
sponge. Never wipe the sheets dry and Going over the surface once more with
use only non-scouring agents for more a squeegee is then neither necessary
intensive cleaning, e. g. ANTISTATIC nor advisable. The sheets may, how-
PLASTICS CLEANER. A Vileda® Mi- ever, be wiped with a clean cloth to
croclean cloth slightly dampened with speed up air drying.
water only has a good, largely streak-
free cleaning effect. To remove more 13.3 Removal of Graffiti and Posters
obstinate and especially greasy stains
from PLEXIGLAS®, petroleum ether or Spray paints on PLEXIGLAS® GS and
benzine may be used. XT can be removed with water-soluble
brush cleaner.
‘Post-treatment’ of the smooth and
glossy PLEXIGLAS® plastic surfaces To this end, cover the paint with a
is very simply done – even by hand – soaked cloth for up to 20 minutes,
using polishing liquid or paste. These depending on type and layer thickness
agents can also be applied by means and then wash it off with plenty of
of an orbital sander, provided it is co- water.
vered with a soft cloth, or a lambswool
polishing wheel.
15SUSTAINABILITY
The Sustainable Development Goals (SDG), adopted
by the United Nations in 2016, all have one goal:
By 2030, all inhabitants of planet Earth should be
able to live in dignity.
To this end, the United Nations has formulated 17 goals
to support global sustainability efforts. The SDGs are our
compass in aligning our sustainability-strategy, creating
innovations and identifying new business opportunities
and take advantage of them.
Products and solutions from Röhm make a measurable
contribution to achieving these goals. This is how we
assume responsibility.
Röhm GmbH ® = registered trademark
Acrylic Products
PLEXIGLAS, EUROPLEX und ACRIFIX are registered trademarks of Röhm GmbH, Darmstadt, Germany.
Riedbahnstraße 70
Certified to DIN EN ISO 9001 (Quality) and DIN EN ISO 14001 (Environment)
64331 Weiterstadt
Germany This information and all further technical advice is based on our present knowledge and experience. However,
it implies no liability or other legal responsibility on our part, including with regard to existing third party
www.plexiglas.de intellectual property rights, especially patent rights. In particular, no warranty, whether express or implied, or
guarantee of product properties in the legal sense is intended or implied. We reserve the right to make any
www.roehm.com
changes according to technological progress or further developments. The customer is not released from
the obligation to conduct careful inspection and testing of incoming goods. Performance of the product
described herein should be verified by testing, which should be carried out only by qualified experts in the sole
responsibility of a customer. Reference to trade names used by other companies is neither a recommendation,
nor does it imply that similar products could not be used.
Ref. no. 311-4 02/2 00/0408/09572 (en)You can also read
