White Paper presented at: 2008 Global Plastics Environmental Conference

USING RECYCLED POLYETHYLENE: AVOIDING THE PITFALLS

Frits R. van der Klooster, A. Chris Ernst

Advanced Blending Technologies

ABSTRACT

Advanced Blending Technologies has developed a software program that creates low cost optimized blends from wide-/off-spec and/or recycled Polyethylene streams of material, by providing blend formulations based on up to seven selectable material properties. The resulting blends are prioritized by least cost and eliminate the need for costly “Trial and Error” experimenting with blends. Combined with rapid testing of incoming material streams, the OptiMISER^® system has successfully been used to convert 100% virgin material processors to 100% recycled usage, at substantial bottom line savings. The OptiMISER system provides the materials engineering needed to maintain production efficiency and insure product quality. Using recycled or wide-/off-spec PE usually results in decreased manufacturing efficiencies, increased scrap and worse; decreased end product quality. This paper discusses a systematic approach which allows the use of up to 100% recycled and/or wide-/off-spec materials while maintaining or even increasing manufacturing efficiencies, reducing process scrap, insuring a consistent end quality product, and significantly reducing overall finished product costs.

INTRODUCTION

Manufacturers using recycled or wide-/off-spec Polyethylene, in place of prime materials, generally experience decreased manufacturing efficiencies, increased scrap rates and lower product quality. Two of the major problems contributing to recycled material problems are;

1) The materials have lost their identity; suppliers of recycled materials describe (often inaccurately[1] ) the material for sale only by Melt Index (M.I.) and Density, and what a manufacturer orders is often different from what is actually received.

2) With hundreds of grades of polyethylene available it is difficult to find adequate quantities of recycled materials that meet the exact specification required by the application.

The OptiMISER System utilizes a systematic approach and advanced blend formulating software that allows manufacturers to achieve high recycled content, up to 100%. A fast and low cost characterization process[2] is used that accurately determines key material properties. An advanced optimization engine uses these properties along with application specific algorithms to create blends of two or more recycled materials that match the manufacturer’s key material and process specifications. The result is that recycled materials can now be used at very high percentages and in applications previously avoided due to critical product quality concerns or third party specifications. This process can be managed in near real time at significant cost savings.

USING RECYCLED POLYETHYLENE; AVOIDING THE PITFALLS.

There are many different grades of Polyethylene (PE) available. Graph 1 depicts this, using only M.I. and Density. Normally a product’s ideal processing and quality specification falls within a very small window. The example shows a large part blowmolding processing window with Density between 0.948 and 0.950, and M.I. between 0.08 and 0.11. Manufacturing people desire a tight window, while those responsible for purchasing want to open the specifications as wide as possible. The smaller the window, the less manufacturing variations, processing and qualityissues; however, this self-imposed limitation often results in increased cost and reduced material availability[3] . The OptiMISER system provides the ability to open or extend the boundaries of the physical properties of the buying window for purchasing, and still allow for a narrow manufacturing process window. The software does this by choosing opposite characteristics from available streams of material and calculates the percentage needed for each stream to meet the narrow process window properties. In this example, the purchasing window was opened up to allow the use of materials with a Density between 0.935 and 0.962, and a M.I. between 0.04 and 0.70. The size of the expanded purchasing window is determined by the capability of the machinery to process the materials.

Graph 1

Since recycled materials have lost their original identity, most processors that use recycled materials rely on supplier/broker provided material specifications, which normally are limited to M.I. and Density. Even if their stated specifications are correct (most brokers don’t test the material and only pass along numbers they have been given by their sources), M.I. is at best a rough indicator as to how a material will process. Additionally, stated values for Density generally do not take into consideration the impact of additives or colorants on material properties, and are often very misleading. The main problems with using M.I. and Density to provide accurate information on a material are explained below.

Melt Index is normally performed at a shear rate far below that encountered in most manufacturing processes[4] . Depending on whether the material has a broad or narrow molecular weight distribution, material will perform very differently during processing: materials with the same M.I., can therefore process differently. The standard test for M.I. is fairly simple and M.I. is a convenient property, but is not a good indicator for how material will actually process. A much better indicator is a term referred to as “Processability”, this value is determined at temperatures and shear rates, similar to those incurred in the actual manufacturing process[5] . Using Processability as the target number in a blend insures consistent performance in the manufacturing process.

Density on the other hand has a direct relationship to Flexural Modulus and therefore is an excellent means of determining the material’s strength, or the relative stiffness of a finished part. However, colorants and fillers will increase the density value and give a false indication of stiffness, unless the effect of these additives is eliminated.

There are many additional material characteristics that may be important to end-product quality. They are usually overlooked until problems occur in the field application. Unless all the key characteristics that are important to the end product are measured for each incoming recycled material, the end result will often be a field product failure, resulting in warranty cost increases. Examples of additional characteristics are ESCR (Environmental Stress Crack Resistance), Impact Resistance, Sag Strength (important for blow molders and thermo-formers), and many more.

With over one billion pounds of Post Consumer Regrind/Repro (PCR) and many more billions of pounds of Post Industrial Regrind/Repro (PIR) PE being made available through recycling each year, the ability to use these materials to replace virgin can translate into significant savings (see graph 2) ranging from $0.05-$0.20 and more per pound replaced.

Graph 2

How can you take advantage of these savings? First you need to ensure that the materials you are using are not contaminated and determine the exact key characteristics[6] appropriate for your process and end product. The old adage “garbage in, garbage out” is especially true when using recycled materials. To insure that the materials are usable, dock side contamination testing and subsequent quick characterization tests[7] were developed. Depending on test results, the incoming material may need to be homogenized before using, or if individual test results do not vary significantly, the material can be used directly.

Blending materials is a known art[8], mostly practiced via “Trial and Error” method[9] . However, in order to insure that a blend meets the desired end specification every time, and is at the lowest possible cost, requires science. Eliminating “Trial and Error” frees the producer to go far beyond their current recycled content limit, which is often reached because of negative impact on process efficiency and product quality. Advanced Blending Technologies has developed the patented OptiMISER software, which allows the user to create optimized blends based on up to seven different material characteristics. Most processes are effectively managed by selecting four key characteristics.

THE OptiMISER^®

The OptiMISER software package can easily be used on the shop floor with minimal training. At setup, the material specifications for each product, which can be machine specific[10], are entered into the software on the “Blend Specification” tab, see figure 1. On the “Inventory” tab, the test results for the incoming material lots are entered. The operator then selects the “Create Blend Solutions” tab and after choosing the desired product, selects “Create Blends” and the OptiMISER will calculate all possible material combinations, prioritized by lowest cost[11] . With the “Log Solution” tab the resulting blends can be saved, which allows for integration with the manufacturer’s Quality system for traceability.

Figure 1

Figure 2 provides a real world example of how three streams of material were combined with the OptiMISER software to provide a solution that is within the narrow process window. The materials used would normally not be considered by purchasing, because the individual streams did not fit within the smaller original Purchasing window. This resulting blend example is equivalent in characteristics to a 50100 grade[12] virgin material, but at a cost of $0.41/lb vs. a current virgin material cost of $0.62/lb.

Figure 2

The number of blend combinations calculated will depend on the number of available material lots and their characteristics. Often a higher cost material will be used because its offsetting properties allow the usage of a greater percentage of a low cost lot in the blend. Therefore, an interesting alternate use for the OptiMISER is as a purchasing tool. The buyer would assign a value to a material based on the properties since not all streams of material are equal in value based on their properties. A material lot with desirable offsetting characteristic(s) has a higher value than a material that limits the percentage of a low cost lot to be used. This can assist the buyer in negotiations, knowing the proper value to the company and what streams to target for acquisition.

ARE YOU REALLY SAVING MONEY?

Often it is difficult to determine the net savings that result from using recycled materials. Increased usage of recycled materials only makes good business sense if the overall Cost of Goods is lower than what can be achieved with virgin materials. As stated earlier, for many processors the use of recycled materials has resulted in increased scrap, lower throughput and reduced quality, using up most of the savings from using lower cost materials. A program that uses recycled materials will only save money, if production efficiencies, scrap rates and quality remain the same, or are improved. Proposing to convert a processor from virgin to wide-/off-spec and/or recycled materials is frequently met with skepticism; “we will have to add manpower, our scrap rates will increase, we need to make capital investments, etc”. To quickly assess whether using recycled materials makes economic sense a “$avings Calculator”[13] was developed (see figure 3). This easy to use tool provides a quick way for a processor to perform “What If” scenarios and determine bottom line savings from using wide-/off-spec, or recycled materials. If needed, the calculator allows for input of additional investments in machinery and personnel, the added cost of testing, etc. and will show the resulting savings after all such investments.

Figure 3

APPLICATIONS

The OptiMISER^® System is currently being used in a wide variety of applications in many different industries: from Sheet Extrusion/Thermoforming to Blow Molding, Injection Molding and Pipe/Conduit manufacturing. Table 1 gives an overview of some of these applications.

INDUSTRY	APPLICATION	SAVINGS
Automotive	Sheet Extrusion/ Thermoforming	Converted from 100% virgin to 95% recycled: Savings >$3MM/year
Construction	Blow Molding	Prior to OptiMISER, was using up to 50% recycled with >50% scrap rates. With OptiMISER, using up to 100% recycled/repro with scrap rates < 5%. Savings > $1MM/year
Industrial	Injection Molding	Successfully using Off-spec railcars with no effect in cycle time or scrap rate increases. Savings > $0.5MM

Table 1

CONCLUSIONS

1. Because information from sellers is often unreliable, incoming materials must be tested for those key characteristics that are Critical to Quality and Critical to Manufacturing.
2. Optimized blends can substantially increase recycled material content with reduced manufacturing variances, improved quality, while lowering overall costs.
3. All costs must be considered before recycled or wide-/off-spec materials can be considered to save money.
4. Blending materials derived from a much broader set of physical properties will substantially increase the selection of material available that may be used to meet both manufacturing and end product specifications.

©2007-2008 Advanced Blending Technologies LLC. All Rights Reserved.

[1] Most recycled material brokers don’t test materials and rely on data provided by their sources. This often results in receipt of materials that have different specifications from what was ordered.

[2] The tests that are recommended are standard tests and proprietary tests that allow for quick characterization of the key properties.

[3] In the software the target blend parameters can be set to as narrow a specification as the process requires. This will result in fewer solutions but will insure a steady stream of consistent material to the machine, requiring less machine adjustments. As opposed to Typically “Trial and Error” blending methods which require frequent machine adjustments.

[4] ASTM D1238 Melt Index test is performed at 190⁰C and a shear rate of approximate 2s^-1. Extrusion processes are generally performed at 176-260⁰C and shear rates of 100-500s^-1, while other processes such as injection molding can experience shear rates up to 10,000s^-1. Because PE is a shear thinning material, the higher the shear rate the lower the viscosity. This is one possible reason why two different lots with the same M.I., will exhibit different rheological behavior during processing.

[5] Depending on the manufacturing process, “Processability” is derived from Rheology data, based on material tested at appropriate temperatures and shear rates similar to the actual process.

[6] It is important that all the properties that are important to Critical To Quality and Critical To Manufacturing are determined. For recycled materials, it is rare that properties beyond M.I. and Density are known for a lot, resulting in unpredictable processing behavior and unknown quality.

[7] To insure that material inventories are kept low, rapid test methods were developed. Most tests take less than 20 minutes, including a test to predict ESCR values.

[8] A web search on “the art of polyethylene blending” will return many examples.

[9] The usual way that “Trial and Error” blending is practiced is to keep adding recycled material to a prime material in a blend until problems occur, then to back off a couple percentage points on the recycled content. The problem with this method is that only a limited amount of recycled material can be used, and that incoming lots vary, such that each lot may have a different limiting percentage.

[10] Although a product’s material specification would stay the same, production on different machinery may allow for a wider processing window, depending on machine mixing capability.

[11] For a short video demonstrating the OptiMISER software; http://www.abtblend.com/demo.asp

[12] 50100 grade is a typical 10 HLMI, 0.950 Density material used for sheet extrusion or blow-molding.

[13] The $avings Calculator can be made available upon request.

Advanced Blending Technologies’ $avings Calculator Provides Snapshot of Polyethylene Resin Savings

March 20 2007, Perrysburg, OH…Advanced Blending Technologies, LLC, has developed a calculator for use in quickly estimating the potential annual savings provided by The OptiMISER® System. The OptiMISER^® System allows recycled and wide-spec polyethylene users to optimize their end quality and production efficiencies, while guaranteeing lower resin cost.

“Anyone interested in estimating savings based on their own current data can set up a web meeting,” said Chris Ernst, partner in and founder of Advanced Blending Technologies, LLC. “No data will be retained and we will make the calculator available by request so that customers can experiment with different data assumptions,” he continued.

According to Ernst, the Savings Calculator has helped prospective customers understand the many ways that implementation of The OptiMISER System lowers costs. Many have identified significant savings ranging from several hundred thousand dollars to millions. “Using our own data in the calculator clearly demonstrated the savings opportunity for our company”, stated one customer.

“We are experts in using, blending and processing the widest variety of recycled and wide-spec PE materials,” said Frits van der Klooster, partner in Advanced Blending Technologies. “Our knowledge is embedded in The OptiMISER System—ensuring a short learning curve and substantial savings over current manufacturing costs,” he said.

For more information about The OptiMISER System visit www.ABTblend.com.

February 7, 2007, Perrysburg, OH …Advanced Blending Technologies, LLC, has been awarded a U.S. Patent for its OptiMISER^® System. The patent was awarded for its “System and method for determining components of a blended plastic material”.

The OptiMISER^® System allows recycled and wide-spec polyethylene users to lower raw material costs, while still ensuring high quality and production efficiencies; eliminating many of the concerns processors currently have with using recycled or wide-spec materials. “This patent validates our innovative approach in the use of recycled and wide-spec for all plastic materials,” said Chris Ernst, founder and partner in Advanced Blending Technologies.

About the Patent

U.S. Patent # 7,158,847 describes Advanced Blending Technologies’ unique method of using a software program to optimize the various characteristics of a multitude of material streams. The OptiMISER^® System ensures that resulting blends not only meet required end specifications, but do so at the lowest possible cost. The system can optimize up to 7 different material properties for each stream of material—while choosing the lowest cost combination that results in a blended material meeting the target specification. According to Chris Ernst, “The optimized blend ensures a consistent stream of material to the process, resulting in higher quality with lower scrap and consistent process parameters.” The OptiMISER System currently is marketed to Polyethylene processors, but can be easily configured to provide similar results for other plastic streams.

About Advanced Blending Technologies, LLC

Founded in 2002, Advanced Blending Technologies is committed to providing recycled and wide-spec PE users with polyethylene expertise and formulation solutions to improve product quality, cut costs and gain a competitive advantage in the marketplace.

Advanced Blending Technologiesassists manufacturers and processors to use recycled materials more efficiently, increasing availability, lowering costs, improving product quality and increasing throughput. The firm also provides assistance in areas ranging from dealing with problematic resins, optimization of blends to meet specific product requirements to opening the purchasing specification window and developing additional low cost material sources.

BusinessWire 6.12.2006

Users of recycled PE resins can now take a quick tour of a new cost-cutting blend formulation solution with Advanced Blending Technologies' new video demo. The four-minute video includes screen shots of The OptiMISER(R) System's blend formulating software and demonstrates the rapid formulation of a wide range of blend recipes based on product specifications and available resins.

Resin is typically the largest cost element within a manufacturing environment. Using recycled polyethylene in a blend reduces costs but presents challenges in throughput, productivity and quality. The OptiMISER System uses advanced formulation software, accurate polyethylene resin characterization and in-depth knowledge of resin behaviors to formulate recycled plastic blends that perform the same as--or better than--virgin materials but at much lower cost.

"The video demonstrates how The OptiMISER System works and describes the benefits it provides," said Frits van der Klooster, partner in Advanced Blending Technologies. "Anyone looking to reduce resin costs can spend just four minutes viewing the demo and understand the potential for their organization," he continued.

The OptiMISER System is now being used in a variety of processes including blow molding, injection molding, pipe and profile extrusion, sheet extrusion and thermoforming. More than a billion pounds of PE materials have already been processed using this system. The OptiMISER System works for all PE processes and material grades, including wide-spec, regrinds, reprocessed and recycled (post-industrial and post-consumer).

About Advanced Blending Technologies, LLC

Founded in 2002, Advanced Blending Technologies is committed to providing recycled PE users with polyethylene expertise and formulation solutions to improve product quality, cut costs and gain a competitive advantage in the marketplace.

Advanced Blending Technologies assists manufacturers and processors to use recycled materials more efficiently, increasing availability, lowering costs, improving product quality and increasing throughput. The firm also provides assistance in areas ranging from dealing with problematic resins, optimization of blends to meet specific product requirements to opening the purchasing specification window and developing additional low cost material sources.

To see the video demo click here: http://www.abtblend.com/demo.asp

FOR IMMEDIATE RELEASE

May 24, 2006, Perrysburg, OH ...Advanced Blending Technologies, LLC, has introduced The OptiMISER^® System, a cost-cutting blend formulation solution designed specifically for recycled PE users. “Blends calculated by the OptiMISER perform the same as virgin materials but at much lower costs,” said Chris Ernst, partner in Advanced Blending Technologies. Normally recycled polyethylene in a blend can reduce costs but can present significant challenges in throughput, productivity and quality. According to Ernst, The OptiMISER System helps manufacturers not only cut costs but improve product quality, productivity and throughput.

The OptiMISER System is a proven software-based solution combining Advanced Blending Technologies' expertise in polyethylene blending and advanced material characterization with one-of-a-kind polyethylene blend formulation software. The OptiMISER Systemuses advanced formulation software, accurate polyethylene resin characterization and in-depth knowledge of resin behaviorsto formulate recycled plastic blends that perform the same as—or better than—virgin materials but at much lower cost.

The OptiMISER System is now being used in a variety of processes including blow molding, injection molding, pipe and profile extrusion, sheet extrusion and thermoforming. More than a billion pounds of PE materials have already been processed using this system.The OptiMISER System works for all PE processes and material grades, including wide-spec, regrinds, reprocessed and recycled (post-industrial and post-consumer).For more information about The OptiMISER System visit www.ABTblend.com or call 419.873.2610.

About Advanced Blending Technologies, LLC

Founded in 2002, Advanced Blending Technologies is committed to providing recycled PE users with polyethylene expertise and formulation solutions to improve product quality, cut costs and gain a competitive advantage in the marketplace.

Advanced Blending Technologiesassists manufacturers and processors to use recycled materials more efficiently, increasing availability, lowering costs, improving product quality and increasing throughput. The firm also provides assistance in areas ranging from dealing with problematic resins, optimization of blends to meet specific product requirements to opening the purchasing specification window and developing additional low cost material sources.

For more information about Advanced Blending Technologies, LLC, visit www.ABTblend.com or call 419.873.2610.