ARALDITE® CY 5538 / ARADUR® HY 5571-2 / Silica Flour

• Good mechanical and electrical properties.
• High thermal shock resistance.

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 thin film degassing mixers that may produce additional self-heating of 10-15 K as a result of friction. For low viscous casting resin systems, conventional anchor mixers are usually sufficient.
• In larger plants, two premixers are used to mix the individual components (resin, hardener) 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, depending 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 pre-drying of the filler. Their moisture content should be < 0.2%.

Specific Instructions

The effective pot-life of the mix is about 1 to 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.

Mold temperature
Conventional vacuum casting: 70 - 100°C

Demolding times (depending on mold temperature and casting volume)
Conventional vacuum casting: 5 - 10 h

PostCure conditions
Conventional vacuum casting: (10 – 12) h at 120 - 130°C or 4 h 140 °C

Total curing cycle (typically):
8 h (80 – 85) °C + 2 h 100°C *demolding* + 12 h (120 – 130) °C or
8 h (80 – 85) °C + 2 h 100°C *demolding* + 4 h 140 °C

• To determine whether cross linking 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 gelling and cure cycles in the manufacturing process could lead to a different cross linking and glass transition temperature respectively.

Conventional gravity casting process under vacuum.

Fig.4.1: Viscosity increase at 60 and 80°C (measurements with Rheomat 115) (Shear velocity D = 10 s-1)

Fig.4.2: Gel time as a function of temperature (measured with Gelnorm Instrument, ISO 9396)

Fig.6.1: Loss factor (tan δ) and Dielectric constant (εr) as a function of temperature (measurement frequency: 50 Hz, IEC 60250)

Fig.6.2: Volume resistivity (ρ) as a function of temperature (measurement voltage: 1000 V, IEC 60093)

Store the components in a dry place according to the storage conditions stated on the label in tightly sealed original containers. Under these conditions, the shelf life will correspond to the expiry date stated on the label. After this date, the product may be processed only after reanalysis. Partly emptied containers should be tightly closed immediately after use.