Liquid Bound Dispersions

Liquid bound dispersions are rubber chemicals that are suspended on a liquid binder system to improve dispersability while still being cost effective. Liquid binder systems are the newest innovation in dispersion technology. They are composed of oil and other additives that reduce the melt point of the rubber chemical allowing for easier dispersion and incorporation time. Liquid bound dispersions are unique, because these systems have lower melt points then most polymers requiring less energy and time to disperse then polymer bound dispersions.

The term liquid bound dispersion can be misleading because the end product is still in a powder form that is beaded. They are less dusting and are easier to weigh then the raw rubber chemical. They produce higher activity levels then polymer bound dispersions which reduces costs.

Liquid bound dispersions can be tailored to any specific formulation more easily then polymer bound dispersions. For demanding applications like aerospace the addition of a foreign polymer from the polymer binder system that is not crosslinked in the finished part can be a cause for concern. Changes within the crosslink density of a rubber article can cause inconsistency leading to the initiation of a failure event; such as inconsistent modulus, tensile rupture, inconsistent tear, or even fatigue failure. Liquid bound dispersions can be tailored to the specific compound, integrating within the rubber matrix with no effect on crosslink density. Therefore, liquid bound dispersions can be used in the most stringent applications.

Liquid bound dispersions function very well because they improve the dispersability of the rubber chemical and reduce the amount of energy required to disperse it. Rubber curatives and accelerators have melt points ranging from 80°C to 230°C. The productive portion of the mix cycle is limited to temperatures below 115°C because the curatives and accelerators within the compound can compromise the scorch safety or start the actual curing process within the rubber compound. These differences between melt point and mixing and or curing temperatures can leave some curatives and accelerators undispersed leading to crosslink density issues. Liquid binder systems coat the rubber chemical and reduce the actual melt point of the rubber chemical leading to increased incorporation times and dispersability.

Liquid bound dispersions are more cost effective then polymer bound dispersions because of the differences in the binder systems. Not only are liquid binder systems more cost effective, they can also improve cycle times which can also reduce cost. Improvements in dispersability will also improve batch to batch consistency resulting in a higher quality product.

Liquid bound dispersions are superior to polymer bound dispersions in regards to many properties; however, they do not render hazardous materials inert, they are not as easy to weigh, and are not suitable for automatic feeding systems. Although liquid bound dispersions do reduce dust they cannot offer the same level of cleanliness seen with polymer bound dispersions.

Liquid bound dispersions can be color coded for easy visual cues to eliminate any handling errors and they do reduce fly loss. In extremely soft compounds liquid binder systems disperse more readily then polymer binder systems. Liquid binder systems also produce less heat history in the rubber chemical then polymer bound dispersions due to differences in mixing processes which can improve the scorch time of the overall finished compound.

Liquid bound dispersions are economical alternatives to polymer bound dispersions for companies looking to improve product quality on a budget. They can improve batch to batch consistency; as well as, increase cycle times.

Polymerics Inc. offers tailored liquid binder systems that will fit all of your dispersion needs. Liquid bound dispersions are packaged in 50 lb. boxes and can be ordered in skid or truckload quantities. For multi ingredient liquid bound dispersions please see the section on chemical blends. For further information please contact customer service at 330-928-2210 x 232 or by e-mail nphillips@polymericsinc.com

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