When developing adhesive labels, there is one prevailing goal: the adhesive must stick to its subject.
Adhesive labels that lose their adhesion over time, or delaminate, are failed products. Extensive product testing ensures that most of these failed label materials never make it to market. However, those that do can cause serious problems for the producer and their customer.
There are innumerable environmental conditions that a package may encounter during storage, transportation, and retail display. Additional factors such as package surface composition or integrity also need to be considered in adhesive choice. The quality and application of adhesives must be impeccable to avoid delamination and any delays or additional costs due to product failure.
In this piece, we highlight the types of adhesion, as well as how failure analysis using surface analysis techniques like Fourier transform infrared spectroscopy (FTIR) analysis can be a helpful troubleshooting tool.
Types of Adhesion
There are 3 basic types of adhesion:
- Specific Adhesion – Molecular attraction between contacting surfaces
- Mechanical Adhesion – The adhesive flows into the microstructures of the bonding surfaces
- Effective Adhesion – Combines specific and mechanical adhesion for optimum joining strength
For manufactured labelling adhesives, effective adhesion is ideal. In effective adhesion, packaging manufacturers choose adhesives that are compatible with the bonding surfaces in order to create the optimal adhesive bonds.
A simple variation in coat weight or contamination can ruin an entire batch of labelled products. When effective adhesion fails and labels delaminate, it can require retailers to waste the product entirely because of quality concerns and regulations. Reprinting labels or altering adhesive formulas could cause significant downtime.
Diagnosing Delamination with FTIR Analysis and ESCA
If a label delaminates and becomes separated from its packaging, there are some diagnostic tests that can help determine the cause of the problem.
Step one in the failure analysis process is often FTIR testing or analysis. This process uses infrared light to analyze the molecular composition of a material. Results of FTIR analysis on a delaminated label can identify the current state of the adhesive after it has failed and can also identify any unknown contaminants that may be present.
By referencing absorbed infrared spectra to a reference library of molecular spectra, FTIR analysis can identify hundreds of thousands of compounds. If the results of FTIR analysis lead to more questions about the product’s adhesion process, Electron Spectroscopy for Chemical Analysis (ESCA) surface mapping may be required.
Also known as X-Ray Photoelectron Spectroscopy, ESCA analysis can analyze the surface of packaging materials and help inform manufacturers about the needs of their adhesives. If the surface has changed materially from what the producer expected, that could be a cause of delamination.
Materials Analysis Labs Solving Manufacturing Problems
While using FTIR analysis and ESCA to solve problems like delamination are non-routine for manufacturers of adhesives and packaging, they are what materials analysis labs like Innovatech Labs do best. If you need help with label delamination, please contact Innovatech Labs today.
If you still find yourself wondering what the real benefits are of failure analysis testing, read our post 3 Ways Failure Analysis Testing Can Benefit Your Manufacturing Company.