Purge Compounds for Thermoplastics

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Purge compounds are extremely important for modern thermoplastics processors, and the use of purging compounds that are designed specifically for operational processes and parameters can provide a significant competitive advantage. Eliminating carbon buildup in screw and barrel assemblies, as well as on die sets, has a significant impact on processing efficiency, scrap rates, die life, and equipment maintenance. Reductions in color or polymer change-over times can significantly enhance operational margins by increasing equipment and labor uptime, allowing organizational assets to be more fully leveraged toward providing complete value to the manufacturing process.

Chem-Trend’s Ultra Purge™ brands of purge compounds cover a wide array of process applications, polymers, operating temperatures, and equipment types. They have been specifically developed to address the challenges faced by thermoplastics processors and add significant value to their operations.

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How to Purge the Injection Molding Machine Screw and Barrel

Learn how to improve purge results by varying low and high backpressure.

How to Purge the Injection Molding Machine Through Parts Production

Learn more about the technique needed for preparing and filling purging compounds in your operation.

How to Recognize Polymer Viscosity to Select the Best Purging Compound Match

Watch and learn how to identify the polymer viscosity to ensure that you’ve selected the best purging compound match for optimal performance.

Why Purging Compounds?

A Chem-Trend purging compound can purge all of your biggest frustrations and keep you moving forward. When compared to traditional cleaning methods, our purging products provide better cleaning, prevent unwanted stoppages, and save you money. Best of all, implementing a Chem-Trend purging compound is simple and can be done without any significant changes in your process. Request a free sample today, and swap unnecessary hassle for unlimited potential.


FAQs: Purging Compounds

Learn more about purging compounds for thermoplastics applications and get answers to frequently asked questions.

Lusin® Purging Compounds and Mold Maintenance Products

The Lusin® portfolio of products incorporates technology from Chem-Trend’s more than 50-year heritage as the world’s leading developer of specialty release agents. Lusin® products are uniquely designed to enhance performance and your bottom line.

Purging Compound Products

Lusin® has been a leader in the thermoplastics industry for more than 60 years. Learn more about how to optimize your thermoplastic processing with Lusin® purging compound products.

The Ultra Purge™ Product Line

Ultra Purge™ provides a broad spectrum of solutions across the Thermoplastics Industry. From Automotive and Medical, to PET requirements, blow molding and extruding technologies, we have a solution that meets your production needs.

Lusin® – Professional Products for Thermoplastics Processing

Download our thermoplastic processing product brochure to find out which of our Lusin®Brand release agents will work for your application.

Introducing Chem-Trend Ultra Purge™ C6090

A solution that liquefies polycarbonates and doesn’t allow them to solidify during the temperature change
process. This is primarily used for automotive headlamps and rear lamps. It’s one product that allows for a
smooth transition between PC and PMMA.

Are there differences between purge compounds for extrusion and purge compounds for injection molding operation?

Purge compounds for extrusion have a lower MFI compare to those used in injection molding. Injection molding purge compounds need to be able to clean a hotrunner at gate size below 0,4 mm.

Are universal purging compounds available that can work with all applications and polymers?

Thermoplastic processing is done in many different ways with many different polymers at a wide range of temperatures. Universal purging compound are available on the market, however they are very compromised offerings that are minimally effective.

Can machine parameters influence the cleaning result of a purge compound?

Various factors like temperature and application time can have an influence on the cleaning result and need to be taken into consideration when selecting and utilizing a purging compound.

Can purge compounds be reground and added to the plastic part as recycle content?

The addition of purge compound into the regrind stream for part production is not recommended as it will affect the physical properties of the final part, likely resulting in rejected parts.

Can purge compounds be reground and reused for future purging?

A purge compound that is contaminated with color, black specks or dissimilar materials has already been saturated or partially saturated with contaminants and will not exhibit the potency of virgin purge compound. Therefore, it should not be reused as it will not produce an efficient purge.

Can purging compounds be used in hot runner systems?

Not all purging compounds are safe for use in hot runner systems; however there are some purging compounds which have been developed to be hot runner safe. The specifications of the manufacturer of the hot runner system should also be noted.

How do you remove material prone to thermal cracking and encrustation from equipment?

Some polymers tend to produce more thermal cracking products and encrustations than others. Special purging compounds have been developed for these polymers.

What are the different types of purging compounds available in the market?

There are two major classes of purging compounds in the market. One is referred to as Mechanical or Abrasive purging compounds – these are compounds where the cleaning process is based on the mechanical action of hard particles, e.g. glass. The other type of purging compounds are Chemical purging compounds – with these the cleaning process relies on chemical additives that initiate some form of chemical reaction. Purging compounds can come in a ready-to-use format where the product can be used directly from the container or in a concentrate format which requires mixing before use.

What are the respective advantages and disadvantages of the different types of purging compounds?

Abrasive purging compounds can be economical to utilize, and are efficient for certain situations but they can damage worm and cylinders. As well, they are not universally usable, for example they cannot be used in hot runner systems.

Chemical-based purging compound tend to be milder than abrasive purging compounds, making them safer for equipment, they are universally usable in hot runner systems, can be injected in cavity and are economical in use. However, they require a polymer matrix which is not always compatible with other polymers.

Purging compounds in the concentrate form can, in principle, be mixed with all polymers universally, but they tend to be more expensive, require time-consuming preparation and create the potential for risk of incorrect dosage. In case of concentrated powders there is also the issue of contamination of conveyor systems and dust loading. Ready-to-use purging compounds are easy to use, there is no risk of incorrect dosage, but they require a polymer matrix which is not always compatible with other polymers.

What positive effects on production do purging compounds provide?

A well-selected purging compound that matches with your process and polymer can provide extensive production benefits such as: time savings (shorter color and material change-over times), material savings, fewer rejects, lower scrap, higher productivity and quality, positive long-term effects on machine cleaning and less wear and tear on machine components.

Why is the use of specialized purging compounds important?

A lot of different polymers are used in thermoplastic processing. The color change operation can be a time and material intensive process, especially in situations where hot runner manifolds are involved. A purge compound specialized for the operating parameters and materials being processed can help to reduce the amount of time and material required to clean the machine tremendously. Specific purge compounds provide maximum performance. Optimal change-over performance can only be achieved with the right purging compound as different polymers are not compatible to each other and the use of an incorrect purge compound may create a material contamination situation.

A brand of Freudenberg.
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