Non Glare Hard Coated Polycarbonate
Sheet and Machined Displays
Polycarbonate
sheet is an excellent plastic for display filters. The
polycarbonate
provides high impact resistance combined with an excellent
flammability rating. In terms of clarity polycarbonate is
comparable to glass, but being a much lighter substrate
polycarbonate is more suitable for applications where
weight is an important consideration. Polycarbonate is a
soft material, from which is easy to machine complex
shapes.
Visiontek
System's polycarbonate sheets are available in a range of
thickness and surface finishes. Our CNC cutting facility
will machine steps, holes with threads and grooves to
strict tolerances.
| Standard
Sheet Size (mm) |
1250
x 2050 |
| Standard
Sheet Thickness (mm) |
0.5,
0.64, 1.0, 1.5, 2.0, 3.0, 4.0 |
Colours
Coloured
polycarbonate sheets can provide effective contrast
enhancement for coloured displays. Typical applications
are LED, Vacuum Fluorescent and Electro-luminescent
displays, where the filter accentuates the colour of the
emitted light, making the back of the display appear
darker.
Specific colours can be matched. There is a minimum order
requirement of 5 sheets.
Lead
Time |
|
| Sheet |
Ex-stock |
| Machined
parts |
7-14
days |
Surface
Finishes
UV
cured clear hard coating
Polycarbonate
is a soft plastic material. Visiontek Systems coat most of
their polycarbonate sheets with a clear hard coat to
eliminate the risk of scratches occurring through general
handling of the product. This coating also provides a high
level of chemical resistance.
75
gloss UV cured clear non-glare hard coating
This
coating provides the benefits of a non-scratch coating
combined with a dispersive non-glare finish to reduce
reflections in conditions where bright sunlight or
overhead lighting may reduce the readability of a display.
They are a cost-effective solution where signal image
quality is not critical and the distance from the display
to the non-glare surface is less than 5mm.
Using
a non-glare etch on the front screen of a CRT display can
cause an interference with the light etching on the tubes.
This will result in a coloured sparkling effect. To
overcome this distortion the screen should be positioned
at least 10cm from the display.
Coating
Specifications - the non-glare and clear hard coatings
meet the following requirements:
| Abrasion
resistance |
Pencil
hardness test - 3H |
| Coating
Adhesion |
No
signs of de-lamination of coating with the cross
hatch test. |
| Haze
and Luminous Transmittance |
BS4410
- haze value of 4% |
| Water
resistance |
Passes
the cross hatch test with no discoloration after
7 days in water at 40°C. |
These
coatings have been formulated to protect plastic
substrates from chemical attack for industrial, commercial
and military uses. They provide outstanding resistance to
all organic solvents and cleaning agents that are in
common use.
The table below shows the resistance to attack from
various chemicals and qualifies the resistance by
reference to short (S), medium (M) and long (L) term
stability.
If
a chemical you are using is not on this list, please
contact Visiontek Systems for a sample for testing.
| Solvent
or Reagent |
Coated
Polycarbonate |
| Ethanol |
L |
| Propanol |
L |
| Acetone |
S |
| MEK |
S |
| Petrol |
L |
| Dilute
Ammonia |
M |
| Dilute
Caustic Soda |
S |
| Concentrated
Caustic Soda |
S |
| Dilute
Organic Acid |
L |
| Dilute
Inorganic Acid |
L |
| S
- Short term resistance |
-
drops / spills |
| M
- Medium Term resistance |
-
up to 8 hours |
| L
- Long term resistance |
-
no attack |
Military
Requirements
These
coatings have been tested in chemical hardness tests for
military applications. The coating prevents damage from
all agents and decontaminants used:
Chemical agents simulated were:
Persistent nerve (VX)
Sulphur Mustard (H)
Properties
General
Properties
|
| Light
transmission |
92° |
|
Thermal
Properties
|
| Thermal
conductivity |
0.21
W/K.m |
DIN52612 |
| Linear
thermal expansion |
65
x 10-6 k-1 |
|
| Heat
Stability |
120°C |
|
Mechanical
Properties
|
| Tensile
strength |
60
N/mm² |
(DIN53455) |
| Elongation
at break |
>100% |
(DIN53455) |
| Modulus
of elasticity |
2300
N/mm² |
(DIN53457) |
| Unnotched
impact strength |
no
break |
(DIN53453) |
| Notched
impact strength |
>30
kJ/m² |
(DIN53453) |
Electrical
Properties
|
| Dielectric
strength |
>30
kV/mm |
(DIN53481) |
| Volume
resistivity |
>1016
ohm.cm |
(DIN53482) |
| Dielectric
constant |
3 |
(DIN53483) |
| Dissipation
factor |
0.001 |
(DIN53483) |
Handling
All
filters are packaged with a protective foil on both sides
or wrapped in tissue. We recommend that the filters are
stored like this.
For all filters, try to limit the number of occasions the
filter is handled as this can easily damage it. A few
important hints are listed hereunder:
- Handle
filters by holding at the edges
- Do
not remove the protective foil until final
installation of the filter. Inspect the filter by
holding it at the edges and peeling back the foil
halfway. Replace the foil and then repeat for the
other half of the filter.
- Inspection
should be carried out in a clean, dust-free
environment. Always use lint free wipes or dry
compressed air.
- Always
ensure that the filter is placed on a clean, dust-free
surface.
Cleaning
Uncoated
polycarbonate is extremely soft and should not be cleaned
by rubbing or dusting with a cloth. Surface dust can be
removed using clean, dry compressed air.
Non-glare and hard coated polycarbonate can be cleaned
with a dry cloth. Do not use alcohol based solutions.
These will cause the polycarbonate to go cloudy and over
time this will cause stress ageing which makes the
polycarbonate brittle.
|