COLLOIDAL GRAPHITE COATING - BM
GRAPHITE
PRODUCT DATA SHEET - BM GRAPHITE
Water-Based, Colloidal Graphite Resistance Coating
Summary
Panel
Dag Type G-97
This colloidal extremely fine particle panel Dag offers a replacement for
current panel Dags now used for CDT and CPT matrix. This product is now
being used by a number of CPT/CDT companies.
Description
BM Graphite offers unsurpassed versatility as a conductive or resistive
coating and impregnant. Currently in use in millions of cathode ray tubes
and other electronic devices, BM Graphite meets the most demanding requirements
due to its high uniformity of manufacture.
Applications
Black Matrix for color television cathode ray tubes
Electrostatic screening, electrostatic finishes on glass envelopes
Coating of electron gun components
Printed circuits - manufactured and repair
Contact material in capacitors, resistors, and other electronic components
Prevention of corona discharge at air gaps under high voltage
Dry lubrication of moving parts in electronic assemblies
Static bleed in computers, office equipment, etc.
Impregnant for glass and other fibers
Typical
Properties
(as supplied)
Pigment
: fine graphite
Fluid
component
: water
Diluent
: deionized water
Color
: black
Consistency
: gel
Density
: 9.1 lb/gal
Solids content (weight)
: 10%
Freezing
: 32 degreeF (0 degreeC)
Flash
point
: none
"Particle
Size"
Average particle size is less than 1 micron and over 90% of the particles
are sub micron.
Resistance
The electrical characteristics of the dry coating can be varied by adjusting
the ratio of concentrate to diluent, the method of application, thickness, and
the type and degree of heat treatment. Resistance coatings have a negative
temperature coefficient of resistance.
Typical
resistance values of the dry coating on a glass substrate are as follows:
Application
Method Thickness (Dry)
Cure Cycle
Resistance
Dip 1:3
1.0 mil
5 minutes @ 300 degreeF (150 degreeC)
30 ohms/sq
Spray
1:5
0.5 mil
Preheat surface 212 degreeF (100 degreeC)
150 ohms/sq
Brush
1:1
0.3 mil Air dry -
room temperature at 70 degreeF
1000 ohms/sq
Application Details
Dilution
For best results, stir the concentrate to break up the gel structure before
adding water. Next, slowly add deionized water to the concentrate.
When a fluid consistency is achieved, water can be added at a more rapid
rate. Failure to achieve correct dilution can result in small gel
structure remaining in the fluid. The presence of these structures can
adversely affect performance. A high-speed and high-shear mixer is
recommended to properly disperse the product. To ensure the absence of
these gel structures, it is recommended that the final blend be passed through a
10 to 50 micron in-line cartridge filter, depending on the viscosity and solids
of the mixture.
Mixing
When mixing larger amounts (one gallon and up), you should first cover the
bottom of the container with several inches of water and mix with a Cowles-type
dissolver blade at 750 to 1,000 rpm, or other high-shear blade. Add the BM
Graphite and slowly add additional water to the BM Graphite while the
mixer is stirring. After mixing is completed, (approximately 30 minutes),
the final mixture should be run through the appropriate filters. Vigorous
or excessive agitation during application, which might add air bubbles to the
mixture, should be avoided. For proper wetting and to prevent spoilage,
the desired pH should be controlled by additions of ammonium hydroxide.
Note:
All water should be deionized.
Application
Method
Diluted BM Graphite may be applied by flow, spray, brush, dip, or sponge
methods. The optimum viscosity for each method is best established by
pretesting. Suggested starting formulations are listed below.
Kilograms
of BM
Graphite:
Kilograms of Water
1
2
1
6
1
10
Before coating, clean all grease and
dirt from the surface to be coated. Preheating the substrate to 140
degreeF will speed drying and lessen flow marks. Coating adhesion can be
increased and the resistance decreased by drying 149 degreeF (65 degreeC) for 2
to 5 minutes. A longer cure at 390 degreeF (200 degreeC) for up to one
hour, 150 degreeF will further stabilize the resistance.
Storage/Shipping/Handling
BM Graphite can be stored at temperatures between 44 and 105 degreeF (5 degree
and 40 degreeC). Do not allow the material to freeze. Product
containers should be cleaned and tightly sealed after use. Shelf life of
this product is 18 months from date of shipment under original seal.
Application
Assistance
Contact www.kemcointernational.com
or call 727-867-8781
Health
& Safety
Harmful if swallowed. May cause eye irritation. Wash thoroughly
after handling. Avoid contact with skin, eyes, and clothing. Use
with exhaust ventilation or wear a mask, if product is sprayed. Avoid
prolonged breathing of vapor, which contains ammonia.
