A pressure sensitive adhesive (PSA) is a type of adhesive that sticks dry at room temperature. It does not require activation by heat or solvents to create a good adhesion on a wide variety of surfaces such as paper, plastic, wood, glass, etc. Adhesion occurs simply by contact or light pressure with a finger or hand.
Many water-based acrylic adhesives (PSA) tend to generate foam due to their aqueous composition. The fact that foam is generated can be critical both in the process of formulation of the adhesive and in its application. In most cases the formation of foam causes problems that adversely affect production and the end result of the product preventing the adhesive from meeting the requirements (adhesion strength, adhesive film transparency or being free from defects). Defoamers are chemical additives that have to remove foam and prevent its formation.
Experts distinguish between two types of foam formation, macrofoam and microfoam, both of which can be removed with a small dose of the defoamer EMULTROL DFM OL-4 by Concentrol. Removing foam can not only increase the speed of production, both yours and your customer’s, but also it avoids flaws and irregularities, helping to reduce production costs.
The defoamer EMULTROL DFM OL-4 has been carefully selected and formulated to provide excellent control of foam in water-based acrylic adhesive (PSA). Applying a small amount allows to eliminate and prevent foam in the adhesive with maximum compatibility, without adverse effects on the performance of the dispersion and with a stable effect over time.
To evaluate the performance of the defoamer EMULTROL DFM OL-4 in water-based acrylic adhesives we measured the formation of macrofoam by the compressed gas injection method, and measured microfoam formation using the agitation method.
To measure the formation of macrofoam we weigh 100g of adhesive, we add the defoamer EMULTROL DFM OL-4 (0.16% dose), we inject nitrogen through a gas diffuser (flow 0.3 L / min) and we measure the increase in height of the foam. The results are then compared to a sample of adhesive without defoamer every 30 seconds for 15 minutes.
- Figure 1. Antifoaming test results on water-based acrylic adhesives (PSA) using the method of injecting compressed gas.
The foam formation measurements are carried out on a sample of 150g of adhesive, to which the defoamer EMULTROL DFM OL-4 (0.16% dose) is added and stirred intensely for 5 minutes at 500rpm. The density of the sample is then determined and the percentage of air is calculated. The results are then compared to an adhesive sample without defoamers.
- Figure 2. Antifoaming test results on water-based acrylic adhesives (PSA) using the method of agitation.
The results of both tests show that EMULTROL DFM OL-4 is a suitable defoamer for the production of water-based acrylic adhesives, allowing optimal control of foam formation in processes such as pumping or recirculation while preventing the presence of entrained air in formulations.
Concentrol has over 75 years of experience in designing, manufacturing and marketing of specialty chemicals, always committed to quality, innovation and cutting edge technology to provide the best possible solutions for each client. Contact us if you want more information about our defoamers for PSA adhesives.
