Len wrote:This is a very sensitive question. These formulation are not well known, nor are they published. You are going to have to do some lab work to fine tune what I'm about to share in a general sense to meet your requirements. I assume you are not in the plastisol business, therefore I'll start this simply.
Plastisol formulation begins w/ PVC dispersion resin. Plasticizer is a major component of the compound or blend. These are liquid systems, where PVC resin is dispersed w/in a plasticizer. Stabilizers and the usual PVC compounding ingredients are also necessary.
Plastisol are made in small quantities by using a small mixer, like a kitchen cake mixer. The liquid blend are then placed in a chamber, desiccating chambers work nicely, and then a vacuum is drawn on the contents to de-aerate the blend.
A simple formulation is as follows: Paste resin = 100 phr. Plasticizer = 60 to 100 phr. Stabilizer = 1.0 to 2.0 phr. ESO = 3 to 5 phr. Filler = 0 to 20 phr, usually PCC. Colorants = 0.5 to 8.0 phr, but as pre-dispersed pastes, not as dry colorants! Secondary plasticizers and diluents are also used, depending on the application technique required. Extender resin can be used, these are usually called blending resins and have a different particle size which can aid in long term viscosity stability.
Start w/ the plasticizer and liquid stabilizer in the mixing bowl. Start the blender and slowly add the PVC resin. After the resin is smoothly blended into the liquid, add the other ingredients. Slowly, you do not want agglomeration of these materials in your blend. Then decant the liquid into a vacuum chamber and de-aerate it.
You can cure this liquid system in a small shallow pan using a common oven. Set the oven at 350 F and cure the sample for about 10 to 15 minutes. De-mold the sample and do your testing on the specimen.
Plasticizer content and type, resin MW selection, stabilizer type, filler loading, and storage temperature will effect your liquid viscosity and determine it's long term viscosity stability... or lack thereof! Be advised that these systems are dynamic.
I wish you good luck. If you start down this path and will share your journey, I'm sure otherknowledgable folks on this site and I will be willing to guide you. This is not a free lunch.
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