LOCTITE AA 326
Harmonization Code : 3907.30.00.40 | Epoxy Mold Compounds containing by weight more than 70 % silicon dioxide
Main features
- One-Component Activator Cure
- Controlled High-Viscosity Placement
- Ferrite-to-Metal Structural Bonding
Product Description
LOCTITE AA 326 is a transparent yellow to light-amber, high-viscosity one-component polyurethane methacrylate structural adhesive for bonding ferrites to plated materials. It cures in close-fitting joints after activator application, with no two-part resin mixing required. The 15,000 to 18,000 mPa s viscosity supports controlled placement, and the recommended bond gap is 0.1 mm, extending to 0.5 mm when activator is applied to both surfaces. Full strength typically develops in 24 to 72 hours, depending on gap, materials, and ambient conditions. The cured adhesive combines structural strength with measured dielectric and thermal properties.
Key features
- One-component activator cure: The adhesive requires no resin mixing and cures after the specified activator process.
- Controlled high-viscosity placement: A 15,000 to 18,000 mPa s viscosity supports application in defined bond gaps.
- Ferrite-to-plated-material bonding: The adhesive is used for electric-motor ferrites and related plated hardware assemblies.
Applications / Suitable for
- Bonding ferrites to plated materials in electric motors
- Loudspeaker hardware assembly
- Jewelry bonding with the specified activator process
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Chemistry Type
Polyurethane methacrylate
Color
Transparent, yellow to light amber liquid
The color
Component System
One component
Describes the number of components that must be supplied, mixed, or activated before application or cure.
Refractive index
1.5
The refractive index determines how much the path of light is bent, or refracted, when entering a material. It is calculated by taking into account the velocity of light in vacuum compared to the velocity of light in the material.
The refractive index calculation can be affected by the wavelength of light and the temperature of the material. Even though it is usually reported on standard wavelengths it is advised to check the TDS for the precise test parameters.
Specific Gravity
1.09
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.
Thermal Properties
Linear thermal expansion
80×10^-6
Specific Heat Capacity
0.3 J/(g⋅°C)
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property. It is also an example of an extensive property since its value is proportional to the size of the system being examined.
Thermal Conductivity
0.1 W/m.K
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.
Physical Properties
Viscosity
18,000 mPa.s
Viscosity is a measurement of a fluid’s resistance to flow.
Viscosity is commonly measured in centiPoise (cP). One cP is defined as
the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP.
A product like honey would have a much higher viscosity -around 10,000 cPs-
compared to water. As a result, honey would flow much slower out of a tipped glass than
water would.
The viscosity of a material can be decreased with an increase in temperature in
order to better suit an application
Mechanical Properties
Elongation
135 %
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.
Electrical Properties
Dielectric Strength
31.5 kV/mm
Dielectric strength is measured in kV per mm and is calculated by the Breakdown voltage divided by the thickness of the tested material.
Those two properties go hand in hand and while Breakdown voltage is always thickness dependent, dielectric strength is a general material property.
As an example, the dielectric strength of Polyimide is 236 kV/mm. If we place 1mm of Polyimide between two electrodes, it will act as an insulator until the voltage between the electrodes reaches 236 kV. At this point it will start acting as a good conductor, causing sparks, potential punctures and current flow.
Surface Resistivity
2×10^17 Ohms/sq
Volume Resistivity
2×10^13 Ohms⋅cm
Volume resistivity, also called volume resistance, bulk resistance or bulk resistivity is a thickness dependent measurement of the resistivity of a material perpendicular to the plane of the surface.
Additional Information
Technical properties
As-supplied / before-processing properties
Typical values and characteristics for the product before cure, application, or assembly.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Appearance | Transparent yellow to light amber liquid | - | As supplied |
| Chemical type | Polyurethane methacrylate | - | One-component material |
| Specific gravity | 1.05 | - | 23 deg C |
| Viscosity | 18,000 | mPa s | Brookfield RVT, spindle 6, 20 rpm, 25 deg C |
| Viscosity | 15,000 | mPa s | EN 12092-MV, 36 s^-1, 25 deg C |
| Recommended bond gap | 0.1 | mm | Standard activator process |
| Maximum gap | 0.5 | mm | Activator applied to both surfaces |
| Cure mechanism | Anaerobic with activator | - | Close-fitting joint |
Technical properties
After-processing / final-state properties
Typical values for the cured, bonded, treated, or in-service product under the listed conditions.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Full-strength development | 24 to 72 | h | Depends on gap, materials, and ambient conditions |
| Elongation at break | 135 | % | Cured 7 d at 23 deg C |
| Tensile strength | 34 | N/mm^2 | Cured 7 d at 23 deg C |
| Tensile modulus | 300 | N/mm^2 | Cured 7 d at 23 deg C |
| Coefficient of thermal expansion | 80 x 10^-6 | K^-1 | Cured material |
| Thermal conductivity | 0.1 | W/(m K) | Cured material |
| Dielectric breakdown strength | 30 | kV/mm | Cured material |
| Lap shear, grit-blasted steel | 15.2 | N/mm^2 | Activator 7649 on one side; cured 24 h at 23 deg C |
| Tensile strength, steel joint | 24 | N/mm^2 | Activator 7649 on one side; cured 24 h at 23 deg C |
