Analysis of common failure modes of single-component polyurethane adhesive

One-component moisture-curing polyurethane adhesive is a highly elastic, medium-low modulus organic adhesive. It is widely used in construction, automobile, rail transit and other industries. In the rail transit industry, one of its most important uses is for bonding windows to car bodies and window frames. We often find bonding failures during use. The editor will analyze several common bonding failure modes and causes:

1. Common bonding failure modes:

1. The adhesive does not solidify for a long time.

2. The adhesive is completely cured but does not stick to the primer.

3. The adhesive is completely cured and adheres well to the primer, but the primer does not stick to the base material.

4. Mixture of multiple failure modes

2. Reason analysis:

1. The first bonding failure mode is usually caused by the adhesive being contaminated by alcohol cleaning agents or acidic substances, resulting in the adhesive not being fully cured, or curing extremely slowly, or curing incompletely. Of course, we first need to determine whether the adhesive cures normally in the natural environment. If the adhesive cures normally, we will then look for the source of pollution in the production process, discover it in time, and remove it in time.

2. The second bonding failure mode, simply put, is that the primer and adhesive do not stick, which is an adhesion failure. The usual reasons are: the primer is contaminated twice after application. Common causes of secondary pollution include: the primer is left standing for a long time, the presence of polished or silicone-containing substances in the bonding workshop, or the surface of the primer is improperly handled by the operator, etc. As a result, the primer and adhesive cannot bond well. Another reason is that the adhesive is dry before bonding to another substrate, which will also cause the adhesive and primer to not stick.

3. The third bonding failure mode is that the cured adhesive strip can be completely or partially peeled off from the surface of the base material. The primer and adhesive strip are well bonded, but fall off from the base material. Reason 1: The primer was not shaken well before use, or the primer failed. The second reason is that applying the primer before the cleaning agent is dry may also cause poor adhesion between the primer and the substrate. Reason three is that the residue of the cleaning agent contaminates the primer.

4. The fourth failure mode usually manifests as a mixture of one or more bonding modes. At this time, we must first analyze which of the above failure phenomena belong, and then specifically solve the problems that exist during the production process. problem.

The above description is the editor's simple analysis of this topic. I hope it will be helpful to everyone. I also hope that all colleagues will express their own views or opinions on this topic.

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