Difference Between Hot Tack and Seal Strength

In the realm of packaging materials testing, understanding the properties and performance of seals is crucial. Two critical parameters often discussed are hot tack and seal strength. While they may seem similar, they are distinct in their applications and the insights they provide into the performance of packaging materials. This article delves into the differences between hot tack and seal strength, referencing ASTM standards F1921 and F2029, and highlights the advantages of using Cell Instruments' hot tack tester for accurate and reliable testing.

What is Hot Tack?

Hot tack refers to the ability of a heat-sealed joint to withstand a tensile force while still hot, immediately after sealing. This property is critical in high-speed packaging operations where the sealed packages are subjected to stresses before they cool down and develop their full seal strength. The hot tack test measures the immediate holding force of the seal and helps in optimizing packaging processes to prevent premature opening of the seals.

What is Seal Strength?

Seal strength, on the other hand, measures the maximum force required to separate a sealed joint after it has cooled down to room temperature. This parameter evaluates the long-term integrity of the seal under various conditions, ensuring that the packaging can withstand handling, transportation, and storage without compromising the contents.

ASTM Standards for Hot Tack and Seal Strength

ASTM F1921 and ASTM F2029 are the primary standards that outline the procedures for testing hot tack and seal strength, respectively.

ASTM F1921: This standard provides guidelines for determining the hot tack force of heat seals using a hot tack tester. It specifies the test method, including the preparation of test specimens, the sealing process, and the measurement of the hot tack force.

ASTM F2029: This standard describes the methodology for measuring the seal strength of flexible barrier materials. It includes details on sample preparation, the sealing process, and the conditions under which the seal strength is measured.

Key Differences Between Hot Tack and Seal Strength

Measurement Timing:

Hot Tack: Measured immediately after the sealing process, while the material is still hot.
Seal Strength: Measured after the sealed material has cooled to room temperature.

Application Focus:

Hot Tack: Critical for high-speed packaging operations where the seal needs to hold immediately after formation.
Seal Strength: Important for assessing the long-term durability and reliability of the seal.

Testing Conditions:

Hot Tack: Involves immediate testing post-sealing, often within milliseconds.
Seal Strength: Involves testing after a period of cooling and conditioning.

Why Choose Cell Instruments' Hot Tack Tester?

Cell Instruments' hot tack tester is designed to provide precise and reliable measurements of hot tack strength, ensuring that packaging materials meet the stringent demands of high-speed production environments. Our instruments offer the following benefits:

Accuracy: Advanced sensors and precise control mechanisms ensure accurate measurement of hot tack force.
Versatility: Suitable for a wide range of materials, including films, laminates, and foils.
Ease of Use: User-friendly interface and robust design make it easy to operate and maintain.
Customization: We offer tailored solutions to meet specific testing requirements and industry standards.

Conclusion

Understanding the difference between hot tack and seal strength is vital for optimizing packaging materials and processes. Hot tack provides insights into the immediate holding force of seals during high-speed operations, while seal strength evaluates the long-term integrity of the seal. By adhering to ASTM standards F1921 and F2029, manufacturers can ensure their packaging materials meet industry requirements.