LE-2441 | One-Part Optically Clear Epoxy Resin

Harmonization Code : 3907.30.00.90 | Polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters, in primary forms : Epoxide resins : Other

LE-2441 | One-Part Optically Clear Epoxy Resin

Main features

High thermal stability (Tg = 157 °C)
UV curable encapsulation
High optical transmittance

Product Description

OPTOLINQ™ LE-2441 is a high-performance UV-curable epoxy resin developed for precision optical bonding and encapsulation. Engineered for fast and tack-free curing under 310–365 nm UV light, it offers superior optical clarity, strong adhesion, and robust thermal resistance. Its high refractive index (1.5665), >89% transmittance from 500 to 900 nm, and glass transition temperature of 157 °C make it ideal for LED optics, fiber-optic components, and sensor assemblies. LE-2441 is a solvent-free, single-component formulation with excellent flowability (viscosity: 2,500 ± 500 cP), and no pot life concerns. RoHS compliant and resistant to oxygen inhibition, it ensures stable processing and long-term performance in high-precision applications.

Product Key Features

Fast UV curing – Cures quickly at 310–365 nm with minimal energy.
Tack-free surface – Oxygen-insensitive curing avoids surface inhibition.
High optical clarity – 90% transmittance at 900 nm; ideal for light-guiding applications.
Optimal refractive index (1.5665), which is ideal for optical components.
High Tg (157 °C) – Excellent thermal resistance for demanding environments.
Low CTE (74 ppm/°C) – Ensures dimensional stability in optical assemblies.
Strong adhesion to Si, Au, die attach materials, and printed circuit board assemblies, and forms airtight seals upon curing.
Solvent-free, single-component – No mixing required; easy to handle and apply.
RoHS compliant – Meets EU Directive 2011/65/EU for environmental safety.

Applications

LED lens encapsulation and UV bonding
Optical fiber and photonic component assembly
Sensor and photodiode sealing
Transparent coatings for display and imaging devices
Precision bonding in optoelectronic modules

Specifications
Additional Information

Technical Specifications

General Properties

Appearance

Appearance
Appearance at room temperature.

Transparent liquid

Refractive index

Refractive index
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.

1.5665

Specific Gravity

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.

1.21

Shelf Life Shelf Life Shelf life is the amount of time after manufacturing that a product is guaranteed to retain its properties. It differs vastly per product and it is based on temperature and storage conditions. The properties can be guaranteed for the temperature and time range indicated on the TDS since those are the ones tested to be the best for the product.
Shelf Life @ 5°C	243 days

Physical Properties

Viscosity

Viscosity
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

2500 mPa.s

Chemical Properties

Moisture absorption

0.3 %

Mechanical Properties

Hardness Hardness Hardness is a dimensionless quantity. There is no direct relationship between measurements in one scale and their equivalent in another scale or another hardness test.
Durometer (Shore D)	88

Electrical Properties

Visible Light Transmission

89 %

Thermal Properties

Coefficient of Thermal Expansion (CTE) Coefficient of Thermal Expansion (CTE) CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material. Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a system consists of an adhesive plus some other solid component.
Coefficient of Thermal Expansion (CTE) , α1 Coefficient of Thermal Expansion (CTE) , α1 CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg). It explains how much a material will expand until it reaches Tg.	74 ppm/°C
Coefficient of Thermal Expansion (CTE), α2 Coefficient of Thermal Expansion (CTE), α2 CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg). It explains the extent to which a material will expand after it passes Tg.	207 ppm/°C

Degradation temperature

Degradation temperature
The temperature at which the materials start losing their properties

377 °C

Glass Transition Temperature (Tg)

Glass Transition Temperature (Tg)
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.

The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.

157 °C

Specific Heat Capacity

Specific Heat Capacity
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.

5770 J/(g⋅°C)

Additional Information

LE-2441 Recommended Curing Conditions

Parameter	Value	Unit
Irradiation Wavelength	310~365	nm
Irradiation Intensity	100	mW/cm²
Irradiation Energy Dose	6000	mW/cm²

Processing Instructions

OPTOLINQ™ LE-2441 should be stored at 2–13 °C. Before use, keep the sealed container at ambient conditions for 1–2 hours. Do not open the lid until the temperature has equalised to prevent moisture condensation.
Ensure that all application surfaces are clean, dry, and free of grease, dust, or mold-release agents. Wipe the surfaces with a suitable organic solvent to remove any contaminants that could affect the resin’s adhesion or curing performance.
Avoid contact with substances that can inhibit curing, such as amines, amine-cured epoxies, or polyurethanes (PU). Direct or indirect exposure to these materials may reduce or completely prevent proper curing of LE-2441. It is recommended to perform compatibility testing prior to production use.
Wear appropriate protective equipment and minimize direct contact with the human body. Refer to the Safety Data Sheet (SDS) before use.