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Slater Plastics are manufacturers of optical filters, contrast
enhancement filters, RFI / EMC shielded windows, instrumentation and display
fascia panels, we also offer a design and consultation service
Optical filters and fascia panels
Optical filters and fascia panels: Slater Plastics are manufacturers
of high quality optical filters and fascia panels. These products are
manufactured to suit individual customer requirements or specifications
and can be made from allyl carbonate or CR39 TM, acrylic, polycarbonate and glass.
All filters can be manufactured to include screen printing and RFI shielding,
( see technical information RFI / EMC Filter windows if necessary ).
Filters can be manufactured to include many characteristics including
; contrast enhancement, reflection control, impact strength, fire specifications,
abrasion and solvent resistance, polarisation and combinations of properties.
Allyl carbonate filter windows (Equivalent to CR39TM)
This product is cast in house from ADC monomer and has a series of properties
that makes it ideal for the production of filter windows and fascia panels.
Properties include :
- Less than half the weight of glass
- Bright surfaces and light transmissions close to optical glass
- Refractive index close to that of crown glass
- High impact strength
- Remarkable abrasion resistance ( approximately 20 times that of acrylic
)
- Resistance to pitting from hot metal sparks, 30 - 40 times higher
than glass and other plastics
- Excellent resistance to acids, alkalis and to all solvents including
aliphatic and aromatic hydrocarbons
- Easy surface dying
- Better scratch resistance than hard coated plastics
- Resistance to distortion by temperatures up to 130° C, a temperature
at which acrylic resins are melted
- U.V. absorbers can be added to help protect LCD displays in strong
sunlight
Typical properties of polymers cast from A D C Monomer
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Optical Properties
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Result
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ASTM TEST METHOD
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| Yellowness Index
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0.73
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D 1925
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| Haze, %
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0.21
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D 1003
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| Refractive Index, n.20 D
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1.50
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D 542
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| Dispersion Factor
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57
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D 542
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| Visible Transmission, %
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93.3
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D 1003
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Ultraviolet Transmission, %
( 3 mm thickness) at 300 nm.
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25.0
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-
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Ultraviolet Transmission, %
( 3 mm thickness) at 340 nm.
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77.0
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-
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Ultraviolet Transmission, %
( 3 mm thickness) at 380 nm.
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88.0
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-
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Physical and mechanical properties
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Result
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ASTM TEST METHOD
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| Density, g/cc
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1.311
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D 792
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| Tensile Modulus, (Mpa)
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2.400
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D 638
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| Taber Abrasion, ( x P.M.M.A.)
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20
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D 1044 (modified)
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| Rockwell Hardness, (M)
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97
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D 785
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| IZOD Impact Resistance KJ/mq.unnotched at 23° C
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7.85
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D 256 (modified)
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| Shrinkage, %
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12.3
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-
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Chemical resistance 7 days immersion at 23°C
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Result
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ASTM TEST METHOD
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| Water : absorption, %
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0.40
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-
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| Water: haze variation, %
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+0.07
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-
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| Acetone : absorption, %
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0.78
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-
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| Acetone: haze variation, %
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0.00
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-
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| Toluene: absorption, %
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0.40
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-
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| Toluene: haze variation, %
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0.00
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-
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| Ethyl Alcohol: 95% : absorption, %
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0.10
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-
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| Ethyl Alcohol: haze variation, %
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+0.05
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-
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| Trichloroethylene: absorption, %
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0.04
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-
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| Trichloroethylene: haze variation, %
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+0.06
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-
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| H.D.T. 1,82 Mpa, C
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69
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D 648
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| Thermal expansion |
| Linear coeff./ C from -40 to 25° C |
0.81 x 10-4 |
| Linear coeff./ C from 25 to 75° C |
1.20 x 10-4 |
| Linear coeff./ C from 75 to 125° C |
1.43 x 10-4 |
allyl carbonate or CR39 TM can be cast from 1 mm thick upwards.
Acrylic Filters.
Acrylic filters are often used for larger displays and also where contrast
enhancement is required ( due to the large range of tints available ).
For these filters we use a high grade cast acrylic which can be obtained
down to 0.5 mm thick.
The large range of tints available allows specific wavelengths to be
transmitted. This can be used to contrast enhance, colour correct or produce
band pass filters. Infra - red filters are also manufactured to block
visible light and transmit IR at around 90%.
All acrylic filters can be finished with a hard coat, for abrasion and
solvent resistance, which can be applied as a gloss or matt surface.
Typical properties of uncoated acrylic filters
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Optical properties
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| Refractive Index nD20
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1.492
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| Light Transmission %
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92
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Physical and mechanical properties
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| Density, g/cc
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1.18
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| Tensile Strength N/mm²
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75
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| Elongation at Break %
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4.5
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| Bending Strength N/mm²
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135
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| Notched Impact Strength
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2
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| Modulus of Elasticity N/mm²
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3300
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Thermal Characteristics
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| Linear coeff./ C 0 - 50° C
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70 x 10-6
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| Vicat softening point °C
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100
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| Temp for continuous use °C
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70
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Polycarbonate Filters.
Polycarbonate is usually used when impact strength or fire retardance
is required. These filters are made from proprietary sheet material and
normally coated with a hard coat to give abrasion and solvent resistance.
There are only a few standard tints available for polycarbonate, but
others can be produced when necessary, in relatively small volumes. We
have several techniques available to enable the production of polycarbonate
contrast enhancement filters.
Properties of the polycarbonate will depend on the selected grade.
Glass Filters.
Glass filters can be produced plane, matt etched or with multi layer AR
coating. These filters can also be toughened when required. Laminations
can be built to include all filtering characteristics already mentioned.
Available Coatings For Acrylic and Polycarbonate.
A range of optical coatings are available for the surfaces of acrylic
and polycarbonate filters. Coatings can offer a selection of the following
characteristics;
- Abrasion resistance
- Solvent resistance
- Anti - glare ( matt coating )
- Anti - mist
- Anti - Newton ring
- Multi - layer anti - reflective ( limited to a small range of product )
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