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CHT Group QSil 220

CHT Group QSil 220 is a transparent and colorless silicone formulation that is ideal for optical applications. Its viscosity profile enables excellent flow around components, and it is excellent for potting complex parts. The chemical composition results in a cured product that is hydrolytically stable as well as reversion-resistant. The silicone elastomer provides electrical insulation and physical shock resistance for components and enables environmental protection.

Product Type: 2K (2 component) Adhesive, Encapsulant, Potting Compound

Application Area: Aerospace Applications, Optical Applications

Cure Method: Chemical Cure, Heat Cure

Chemical Family: Silicones

Technical Data Sheet
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Knowde Enhanced TDS

Identification & Functionality

Chemical Family

Features & Benefits

Key Features
  • Low linear shrinkage
  • Non-yellowing catalyst system
  • Self-bonding without primer, requires cure at elevated temperature to build adhesion and develop full physical properties
  • Can be mixed by hand or machine dispensed

Applications & Uses

Use and Cure Information

Important

  • In order to achieve optimum performance, the same lot number of the A and B components should be used. Mixed lots may not obtain the performance criteria listed on the TDS or Certificate of Analysis.
  • The 'A' part of the product contains the platinum catalyst; great care should be taken when using automatic dispensing equipment. Please ensure that it is not contaminated by residual hydride containing rubber (Part B) in the dispensing equipment, as curing will result. If in doubt, it is advised to thoroughly purge the equipment with a suitable hydrocarbon solvent or silicone fluid.

Mixing

  • Both the ‘A’ and ‘B’ parts should be well stirred to ensure the material is uniform. If utilizing machine-dispense, ensure the mixing device has sufficient elements to fully homogenize the components of the formulation.
  • Place the required amount of ‘A’ and ‘B’ parts by weight at the mix ratio shown opposite, in a clean plastic or metal container of approximately 3 times their volume, and mix until the color of the mixture is uniform. For best results, we recommend vacuum degassing. Degas by intermittent evacuation, the larger volume ofthe mixing vessel helps prevent overflow during this operation. In the case of automatic dispensing with static mixing head, the two components should be degassed before processing. Recommended vacuum conditions are 30-50 mbar intermittently over 5-10 minutes.

Inhibition of Cure

Great care must be taken when handling and mixing all addition cured silicone elastomer systems, ensuring that all the mixing tools (vessels and spatulas) are clean and constructed in materials which do not interfere with the curing mechanism. The cure of the silicone can be inhibited by the presence of compounds of nitrogen, sulfur, phosphorus and arsenic; organotin catalysts and PVC stabilizers; epoxy resin catalysts and even contact with materials containing certain of these substances e.g. molding clays, sulfur vulcanized rubbers, condensationcure silicone rubbers, onion and garlic.

Curing Conditions

  • The data offers a guide to the rate of cure at various temperatures, mixing of the components at temperatures between 15 and 25 °C is recommended to ensure adequate pot life for degassing and handling. The pot life can be extended to several hours by chilling the components before mixing.
  • It is important to check the compatibility in preliminary tests if unknown substrates are used.
  • Some formulations are not designed to cure at room temperature and may not develop full physical properties if cured below the minimum listed temperature. The recommended cure temperatures and times are provided for guidance only. The end user must test in their application and process as the quantity of material, size of part, and method of applying heat will influence time and temperature requirements.

Properties

Flame Rating
Physical Form
Typical Properties
ValueUnitsTest Method / Conditions
Mix Ratio10:1
Tensile Strength450.0psi
Elongation200.0%
Dielectric Strength500.0V/mil
Volume Resistivity2.57x10¹⁴ohm-cm
Electrical Properties
ValueUnitsTest Method / Conditions
Volume Resistivity1.7 x 10¹⁵Ω.cmASTM D- 257
Cured Properties
ValueUnitsTest Method / Conditions
Elongation (at Break)150.0%
Hardness Shore A30.0ISO 37
Linear Coefficient of Thermal Expansion322.0ppm/°CASTM D 2240-95
Linear Shrinkagemax. 0.1%
Working Temperature Range-55 - 204°C
Refractive Index (at 589 nm)1.406
Tensile Strength2.07N/mm²ISO 37
Thermal Conductivity0.18W/mK
UL File NumberQMFZ2.E205830
Mixed Viscosity4100.0cps
Shore A Hardness29.0Durometer
Volume Resistivity5.58 x 10¹⁴Ω.cm
Uncured Properties
ValueUnitsTest Method / Conditions
Gel Time (at 25°C)min. 24Hours
Specific Gravity (Component A)1.02
Specific Gravity (Component B)1.01
Viscosity (Component A)5000.0cPBrookfield
Viscosity (Component B)600.0cPBrookfield
Uncured Product Property
Color A Transparent and colorless
Color B Transparent and colorless
Cure Profile

60 mins at 150°C, 180 mins at 120°C

Cure Type Addition
Mix Ratio By Weight 10:1
Rheology Liquid, Newtonian
Self Bonding Yes

Regulatory & Compliance

Certifications & Compliance

Packaging & Availability

Packaging

CHT silicone elastomers are available in a variety packaging including bulk containers.

Storage & Handling

Shelf Life
24 Months
Storage Conditions

Maximum storage temperature is 38 °C / 100 °F