ARALDITE® CY 225 / ARADUR® HY 925-1 / Filler Silica flour

• High mechanical and electrical properties at elevated temperature
• Very high thermal shock resistance
• Excellent toughness combined with elevated glass transition temperature

• Automatic pressure gelation process (APG)
• Conventional gravity casting process under vacuum

• Indoor electrical insulators for medium and high voltage, such as switch and apparatus components.
• Encapsulation of large metal parts.
• Recommended for applications with long-term stresses up to service temperature of 85°C.

General instructions for preparing liquid resin systems

• Long pot life is desirable in the processing of any casting resin system. Mix all of the components together very thoroughly at room temperature or slightly above and under vacuum. Intensive wetting of the filler is extremely important. Proper mixing will result in:

1. better flow properties and reduced tendency to shrinkage
2. lower internal stresses and therefore improved mechanical properties on object
3. improved partial diskharge behavior in high voltage applications.

• For the mixing of medium- to high viscous casting resin systems and for mixing at lower temperatures, we recommend special degassing mixers that may produce additional selfheating of 10-15 K as a result of friction. For low viscous casting resin sys-tems, conventional mixers are usually sufficient.
• In larger plants, the individual components (resin, hardener) are mixed with the respective quantities of fillers and additives under vacuum. Metering pumps then feed these premixes to the final mixer or a continuous mixer. The individual premixes can be stored at elevated temperature (about 60°C) for up to about 1 week, de-pending on formulation. Intermittent agitation during storage is advisable to prevent filler sedimentation.
• Mixing time can vary from 0.5 to 3 hours, depending on mixing temperature, quantity, mixing equipment and the particular application. The required vacuum is 0.5 to 8 mbar. The vapor pressure of the individual components should be taken into account. In the case of dielectrically highly stressed parts, we recommend checking the quality consistency and predrying of the filler. Their moisture content should be <0.2%.

Specific Instructions

The effective pot-life of the mix is about 2 days at temperatures below 25°C. Conventional batch mixers should be cleaned once a week or at the end of work. For longer interruptions of work, the pipes of the mixing and metering installllations have to be cooled and cleaned with the resin component to prevent sedimentation and/or undesired viscosity increase. Interruptions over a week-end (approx. 48h) without cleaning are possible if the pipes are cooled at temperatures below 18°C. Viscosity increase and gel time at various temperatures.

Mold temperature
APG process: 130 - 160°C
Conventional vacuum casting: 70 - 100°C

Demolding times (depending on mold temperature and casting volume)
APG process: 10 - 40 min
Conventional vacuum casting: 5 - 8 h

Cure conditions
APG process (minimal postcure): 4h at 130°C or 3h at 140°C
Conventional vacuum casting: 12h at 130°C or 8h at 140°C

• To determine whether crosslinking has been carried to completion and the final properties are optimal, it is necessary to carry out relevant measurements on the actual object or to measure the glass transition temperature. Different geling and cure cycles in the manufacturing process could lead to a different crosslinking and glass transition temperature respectively

Processing Viscosities

Fig.4.1: Viscosity increase at 60 and 80°C (measurements with Brookfield)

Fig.4.2: Initial viscosity in function of temperature
(measurements with Rheomat 115, D=10S-1)

Gelation-/Cure Times

Fig.4.4: Geltime measured in function of temperature
(measurement with Gelnorm Instrument/ DIN 16945/6.3.1)

Mechanical and Physical Properties

Fig.5.1: Shear modulus (G') and mechanical loss factor (tan δ) as a function of temperature (measured at 1 Hz)
(ISO 6721/ DIN 53445, method C)

Fig.5.2: Coefficient of linear thermal expansion (α) as a function of temperature (reference temperature: 23°C)
DIN 53752

Electrical Properties
 

Fig.6.1: Loss factor (tan δ) and dielectric constant (εr) as a function of temperature (measurement frequency: 50 Hz)
(IEC 250/ DIN 53483)

Fig.6.2: Volume resistivity (ρ) as a function of temperature (measurement voltage: 1000 V)
(IEC 93/ DIN 53482)

Fig.6.3: Breakdown field strength (Ed) in function of temperature
DIN/ VDE 0303/ part 2 (A = raising test / B = 5 min step test)
Test specimen with embedded Rogowski electrodes

Fig.6.5: Life time curves of the electric field stress (E) at 20, 50, 85, 105 and 150°C
Test specimen with embedded sphere electrodes

Thermal Endurance

Fig.7.1: Weight loss (specimen: 50x50x3 mm)
(limit: 4.0%)

Fig.7.2: TI 150 / 174 (weight loss 1.2%)
TI 186 / 210 (weight loss 4.0%)
 

Fig.7.3: Loss of flexural strength (limit: 50%)
ISO 178

Fig.7.4: TI 199 / 240 (flexural strength)

Tensile Creep Test acc.

Fig.7.5: Elongation (ε) in function of temperature at 23, 50 and 85°C
Tensile strain: 20 N/mm2

Fig.7.6: Creep diagram at 23°C
Max. tensile strain in f (load period)

Fig.7.7: Creep diagram at 50°C
Max. tensile strain in f (load period)

Fig.7.8: Creep diagram at 85°C
Max. tensile strain in f (load period)

Thermal shock resistance

Fig.8.1: Crack resistance / Temperature shock test
Passed specimen (%) in f (Temp. step)
Mean failure temperature: - 15°C
Embedded metal parts with 2 mm radius

Fig.8.2: Thermal shock test diagram

Contamination of the eyes by resin, hardener or casting mix should be treatedimmediately by flushing with clean, running water for 10 to 15 minutes. A doctor should then be consulted.
Material smeared or splashed on the skinshould be dabbed off, and the contaminated area then washed and treated with a cleansing cream (see above). A doctor should be consulted in the event of severe irritation or burns. Contaminated clothing should be changed immediately.
Anyone taken ill after inhalingvapors should be moved out of doors immediately. In all cases of doubt call for medical assistance.

Store the components at 18-25°C, in tightly sealed and dry, if possible, in original containers. Under these conditions, the shelf life will correspond to the expiration date stated on the label. After this date, the product may be processed only following reanalysis. Partly emptied containers should be closed tightly immediately after use.