Preparation of One-component Cross-linked Acrylic Pressure-sensitive Adhesives (II)

2.3 The effect of baking temperature and time on cross-linking

Cross-linked pressure-sensitive adhesives generally undergo cross-linking during the coating drying process. The more thorough cross-linking, the better the effect, and the more stable the performance of the adhesive tape. Conversely, if the glue is not fully cross-linked during baking, the glue will continue to cross-link during the storage process, thus making the performance of the tape unstable and inconvenient for quality control. As can be seen from Table 3, as the temperature increases, the peel strength gradually decreases. Wells tend to stabilize. This shows that cross-linking gradually complete. From the experimental results, the peeling strength was basically stable after baking at 120°C or more for three minutes. As can be seen from Table 4, the baking time also has a great influence on the cross-linking. The baking time is too short, the glue is not dry or the cross-linking is incomplete, the cohesive strength of the glue is low, and the purpose of cross-linking is not achieved. Only when the baking time is more than 3 minutes, the cross-linking is basically completed.

2.4 The storage stability of glue

The storage stability of the glue after adding the cross-linking agent is very important for production and sales. For this purpose, we placed the adhesive after the addition of the cross-linking agent, and measured the viscosity and peel strength after different time periods (Table 5). The results show that both the laboratory samples and the mass produced in the workshop have good storage stability. After four months at room temperature, the peel force did not decrease. This indicates that the cross-linking agent does not fail in the pressure-sensitive adhesive solution, and only a very slow cross-linking effect occurs with the adhesive. This slow cross-linking results in a slight increase in the viscosity of the glue but does not affect the coating effect.

2.5 The stability of the tape performance

We also examined the stability of the tape properties (Table 6). As can be seen from Table 6, the peel strength of the tape slightly decreased with time (except Sample C). This shows that under the coating conditions, cross-linking is still not very thorough, but after 3 days, the peel strength has basically stabilized. This is consistent with the results in Table 3 and Table 4. Due to the large amount of cross-linking agent added to Sample C, it is easy to fully react all the cross-linking functional groups in a short period of time to achieve complete cross-linking.

3 Conclusions <br> Stabilized single-component cross-linked acrylate pressure-sensitive adhesives have been successfully developed using a stabilizing cross-linking agent. The performance of the glue can be adjusted by adjusting the amount of cross-linking agent. The volume production in the workshop proved that the production process is reasonable and the product performance is stable.



Source: 21st Century Fine Chemicals Network