3M 281

Harmonization Code : 3506.91.90.99 | Prepared glues and other prepared adhesives, not elsewhere specified or included; products suitable for use as glues or adhesives, put up for retail sale as glues or adhesives, not exceeding a net weight of 1 kg ; Adhesives based on polymers of headings 3901 to 3913 or on rubber; Other ; Other

3M 281

Main features

  • Class F (155 deg C) Temperature Rating
  • Thermally Conductive Encapsulation
  • Upgraded Structural Characteristics

Product Description

3M™ Scotchcast™ Electrical Resin 281 is a two-part, semi-flexible, filled epoxy liquid resin engineered for the impregnation and encapsulation of electrical and electronic components. It is characterized by high temperature and electrical stability, maintaining its flexibility even after prolonged heat aging. This resin is designed for applications requiring greater mechanical strength, higher tensile strength, better thermal shock resistance, and higher thermal conductivity than standard encapsulants like Resin 241.

Key features

  • High temperature rating: Rated for Class F (155°C) continuous service, ensuring reliable performance in high-heat environments.
  • High thermal conductivity: Effectively dissipates heat to protect internal components from thermal stress and failure.
  • Flexible curing profile: Can be cured at low temperatures, though higher temperature cure schedules optimize mechanical properties.

Applications / Suitable for

  • Impregnation and encapsulation of coils and transformers
  • Potting of motors
  • Protection of electrical and electronic components
Product Family

3M 281

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TDS, SDS & Technical Documents

Technical Specifications

General Properties
Appearance
Appearance at room temperature.
Gray
Color
The color
Cream
Mix Ratio
The amount of a constituent divided by the total amount of all other constituents in a mixture
2:3
Solids
100 %
Specific Gravity
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.
1.43
Work life @25°C
Work life is the amount of time we have to work with a material until it is no longer able to be easily worked and applied on a substrate. It is based on the change in viscosity and it can rely on the application requirements.
1.5 hours
Physical Properties
Open time
90 minutes
Viscosity (Part A)
320,000 mPa.s
Viscosity (Part B)
38,000 mPa.s
Mechanical Properties
Elongation
Elongation is the process of lengthening something. It is a percentage that measures the initial, unstressed, length compared to the length of the material right before it breaks. It is commonly referred to as Ultimate Elongation or Tensile Elongation at break.
45 %
Thermal Properties
Flash Point
The flashpoint of a solvent is the lowest possible temperature at which it can vaporize to form an ignitable vapor. Flashpoint is often confused with “autoignition temperature”, which is the temperature at which a solvent ignites without an ignition source.
A : 202°C (395°F)/ B : 188°C (370°F) °C
Thermal Conductivity
Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance. Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system.
0.5 W/m.K

Additional Information

Technical properties

As-supplied / before-processing properties

Typical properties; these values are not intended for use in preparing specifications.

Property Value Unit Method / condition
Mix Ratio (Weight) 2:3 - A:B
Mix Ratio (Volume) 37:63 % A:B
Initial Viscosity 320,000 cps Part A at 23°C (73°F)
Initial Viscosity 38,000 cps Part B at 23°C (73°F)
Mixed Viscosity 75,000 cps at 23°C (73°F)
Flash Point 202 °C Part A (395°F)
Flash Point 188 °C Part B (370°F)
Gel Time 21 minutes at 121°C
Technical properties

After-processing / final-state properties

Typical properties; these values are not intended for use in preparing specifications. Properties measured at 23°C (73°F) unless otherwise stated.

Property Value Unit Method / condition
Color Cream - -
Specific Gravity 1.43 - Cured
Hardness 65 Shore D Instantaneous
Compressive Strength 3500 psi 10% Compression
Tensile Strength 2100 psi 1/8" x 1/2" Sample
Elongation 45 % at break
Flexural Strength 1250 psi 1/2" x 1/2" Sample
Electric Strength 350 V/mil 1/8" (3.175 mm) sample

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