For specification learners, the challenge is not only recognizing the numbers in a TPU granules data line. It is understanding what each parameter can and cannot tell you. Melt-Index relates to melt flow under stated test conditions, hardness describes indentation resistance and perceived firmness, and softening point gives a thermal softening clue rather than a complete processing window. Aoyutec’s AY-TPU series, including AY-6595, AY-6530, AY-6585, and AY-6535, offers a useful reference for reading these terms, but the parameters should be treated as laboratory specification clues rather than standalone engineering conclusions.
Melt Index, Hardness, and Softening Point Describe Different Material Behaviors
A specification sheet for TPU hot melt adhesive granules often looks compact, but the parameters are not interchangeable. Melt-Index is mainly a flow-related indicator: it helps readers understand how readily a thermoplastic material may move when melted under a defined temperature and load. In the aoyutec TPU granules reference, Melt-Index values appear with conditions such as 150℃ / 2.16KG or 120℃ / 2.16KG. That condition line is part of the meaning, not a footnote. A value measured at 120℃ should not be treated as directly comparable to one measured at 150℃ without recognizing that heat level affects melt behavior. Hardness answers a different question. In these TPU granules with softening point and hardness parameters, hardness is expressed as Shore A ranges such as 70A-80A, 75A-85A, and 85A-90A. Shore hardness is an indentation hardness concept, meaning it reflects how a material resists being pressed by a defined durometer method. For a specification learner, this makes hardness closer to a firmness or hand-feel clue than a direct bond-strength statement. A lower Shore A range may suggest a softer material feel than a higher range, but it does not by itself confirm elasticity, adhesion, durability, wash resistance, or suitability for a particular substrate. Softening point adds a thermal dimension, but it also needs careful reading. A softening point range such as 65-75℃, 80-90℃, 105-115℃, or 130-140℃ indicates a temperature-related transition clue for the material, not a complete instruction for coating, lamination, pressing, or activation. Polymer thermal behavior can be characterized through thermal analysis methods, yet that general knowledge should not be confused with the exact method behind a product-page softening point. In practical reading, softening point helps separate low-temperature and higher-temperature material behavior at a specification level, while process validation still depends on equipment, substrate, pressure, dwell time, and test method.
Reading AY TPU Parameter Lines Without Turning Them Into a Ranking
The AY-6595, AY-6530, AY-6585, and AY-6535 examples are useful because they show how several parameter dimensions appear together. AY-6595 is listed with a Melt-Index of 5-25 at 150℃ / 2.16KG, hardness of 70A-80A, and softening point of 80-90℃. AY-6530 uses 5-15 at 150℃ / 2.16KG, hardness of 75A-85A, and softening point of 105-115℃. AY-6585 is different because its Melt-Index is 20-40 at 120℃ / 2.16KG, with hardness of 70A-80A and softening point of 65-75℃. AY-6535 is listed at 5-15 under 150℃ / 2.16KG, with 85A-90A hardness and 130-140℃ softening point. These numbers should be read as specification clues, not as a best-to-worst ladder.
- Melt-Index must stay connected to temperature and load.The AY-6585 Melt-Index range looks higher than some other values, but it is measured at 120℃ rather than 150℃. Without holding test conditions in view, readers may mistake a conditional flow measurement for an absolute material ranking.
- Hardness ranges describe firmness bands rather than full performance.A 70A-80A TPU granule and an 85A-90A TPU granule communicate different indentation hardness ranges. That can support an early understanding of material feel, but it does not replace adhesion testing, lamination trials, or application-specific performance review.
- Softening point ranges help identify thermal softening clues.The listed span from 65-75℃ to 130-140℃ suggests different thermal behavior across the series. However, softening point should not be converted directly into a recommended machine temperature or a guaranteed heat-resistance limit without further method and application data.
- Custom TPU granules should be understood as a communication concept.The phrase custom TPU granules can signal that material requirements may be discussed, especially in B2B conversations with a TPU hot melt adhesive manufacturer or TPU hot melt adhesive supplier. It should not be read as proof that every parameter, range, MOQ, lead time, or formulation option is freely selectable.
This way of reading keeps the specification useful without overextending it. For example, AY-6585’s lower softening point range may help a reader recognize why it is associated with low-temperature textile lamination language, while AY-6535’s higher hardness and softening point ranges help explain why it appears with medium and high temperature lamination wording. Still, this article is decoding parameters, not assigning application suitability. The appropriate conclusion from these lines is that the models present different flow, hardness, and thermal softening signals that deserve context-aware interpretation.
Laboratory Data and Test Conditions Define the Boundary of Specification Meaning
The most important boundary in TPU granule specification reading is that laboratory data is not the same as guaranteed application behavior. Aoyutec’s TPU information includes a caution that technical data is provided by laboratory testing and is not guaranteed because testing environments may differ. For readers, that note is not a weakness in the data; it is a reminder of how material specifications work. Laboratory numbers are produced under controlled conditions, while real bonding or lamination outcomes are shaped by heat transfer, substrate surface, coating thickness, pressure, line speed, cooling behavior, and downstream handling. This is why external standards help explain parameter categories without proving performance for any one AY-TPU model. ISO 868 supports the general idea that Shore hardness is an indentation hardness measurement for plastics and ebonite, which helps readers interpret 70A-90A style hardness expressions. ISO 11357-3 supports the broader point that polymer melting and crystallization behavior can be evaluated through differential scanning calorimetry, which gives context for thermal characterization. However, those standards should not be used to claim that a specific aoyutec grade has a particular processing window, certified application result, or exact softening point method unless the product documentation states that method and test basis. For specification learners, the reusable method is to ask what kind of behavior a number represents before comparing it. Melt-Index belongs to melt flow under stated conditions. Hardness belongs to indentation resistance and firmness range. Softening point belongs to thermal softening behavior as reported in that product context. The more a reader keeps these categories separate, the less likely they are to overread the specification. This is especially important when the page also includes terms such as TPU Hot Melt Powder, TPU Granule, and TPU hot melt adhesive granules. Those naming differences can help locate the material category, but they do not remove the need to read each parameter within its own measurement boundary.
Conclusion
Melt-Index, hardness, and softening point are useful only when they are read as separate specification signals. Melt-Index points toward flow behavior under stated temperature and load, hardness points toward Shore A indentation firmness, and softening point points toward thermal softening behavior. The AY-6595, AY-6530, AY-6585, and AY-6535 data on aoyutec provides a practical reference for understanding TPU granules with softening point and hardness parameters, but it should not be turned into a complete engineering selection chart. A careful next step is to review the model data together with the stated test conditions and remember that laboratory values need application-level confirmation.
FAQ
Q：What does hardness mean in TPU granule specifications?
A：Hardness in TPU granule specifications usually refers to Shore hardness, commonly shown as Shore A values for flexible thermoplastic materials. It describes resistance to indentation under a defined durometer method, so it is best understood as a firmness or material feel indicator. It does not directly prove adhesion strength, elasticity, durability, or suitability for a specific lamination process.
Q：Why should Melt-Index values be read with their test temperature and load?
A：Melt-Index is meaningful only when the test temperature and load are kept with the value because thermoplastic flow changes with heat and applied force. A TPU granule measured at 120℃ / 2.16KG should not be compared as if it were measured under the same condition as one tested at 150℃ / 2.16KG. The condition is part of the specification.
Q：Do custom TPU granules always mean every parameter can be freely specified?
A：No. Custom TPU granules should be understood as a B2B material communication term, not an open promise that every parameter can be freely chosen. A supplier may discuss performance needs, specifications, or application goals, but available customization scope, development process, MOQ, timing, and exact parameter feasibility must be confirmed separately.
Sources / References
ISO 11357-3:2018 Plastics Differential scanning calorimetry Part 3
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