manufacturing, the performance of glue is directly related to the structural strength and service life of the product. We often encounter such problems: the board glue becomes brittle, easy to crack, and lacks toughness after curing , which not only affects the quality of the product, but also may lead to rework, scrapping, and increase costs.
So, what are the reasons why glue becomes brittle after curing? How to prevent it? The following are common analyses and suggestions:
Common reasons that cause the board glue to become brittle:
1. The volatile components are lost too quickly
Some glues (such as solvent-based glues) contain a large amount of volatile organic components, which play a role in dissolving and flowing during the curing process. If these components evaporate too quickly during the construction process , the glue layer will shrink severely and the internal stress will increase, thus losing its original flexibility and eventually becoming brittle.
2. Temperature fluctuation or low temperature curing
Glue is very sensitive to temperature. Curing at low temperatures may result in inadequate crosslinking, slow hardening of the glue layer or loose structure; while uneven curing at high temperatures may also induce thermal stress, causing the glue layer to break or become brittle.
3. Aging and decomposition
Long-term exposure to ultraviolet light, heat or humidity may cause the glue to degrade or oxidize, especially for light-sensitive and heat-sensitive glues (such as some polyurethane glues). The aged glue layer will gradually lose its elasticity and eventually become cracked and brittle.
4. Imbalanced glue ratio (especially two-component glue)
If two-component glue is used, such as polyurethane A/B group, the inaccurate ratio will lead to insufficient or excessive crosslinking density, affecting the final physical properties. Improper ratio is a common but easily overlooked reason in industrial sites.
5. Unsuitable use environment
When glue solidifies in an overly dry, humid or high ultraviolet radiation environment , its physical properties may become abnormal, showing signs of hardening and becoming brittle, especially the glue layer without surface protection treatment is more prone to problems.
6. Improper storage conditions
Long-term exposure of glue to air, high temperature or low temperature environment may cause components to precipitate and reaction activity to decrease, resulting in unstable performance in actual use and increased brittleness after curing.
Suggestions to prevent glue from becoming brittle :
- Strictly control the glue ratio , especially the two-component glue needs to be automatically mixed using precise metering equipment
- Apply the appropriate temperature and humidity conditions to avoid curing in low temperature or high humidity environments
- Store the glue in a cool and dry place and seal it according to the manufacturer’s instructions to prevent premature aging.
- Check the glue condition before construction . If the glue is found to be precipitated, abnormal in viscosity or crystallized, stop using it.
- Priority should be given to special glues with strong weather resistance and aging resistance , such as industrial-grade polyurethane structural glue, epoxy glue, etc.
- For the finished adhesive layer, it is recommended to carry out surface protection treatment, such as spraying UV protective coating or edge sealing process.
Conclusion
The brittleness of glue after curing is not caused by a single factor, but the result of the combined influence of formula, construction environment, storage and transportation methods, etc. In the board composite process, improving the level of glue selection and application management is an important guarantee to ensure product performance and stability.
If you are facing problems such as glue embrittlement, delamination or cracking, please contact us to obtain professional glue solutions suitable for different board processes and environments.
