February 2010

President’s Message

2010 kicked off with a fantastic program for our processors. Kurt Hayden and Chuck O’Toole did a great job coordinating with the Houston Community College and RJG to put on a program titled Decoupled Molding and Cavity Pressure Sensing. RJG provided tooling for a class room and hands on demonstration of process repeatability by the use of Cavity Pressure sensors and scientific molding techniques. We have a great partner in the Houston Community College that has opened the use of their facilities and offered to support our on-going programs. I am excited about this resource and look forward to future collaboration to bring educational programs to processors and the broader community.

February is upon us and our focus is on the International Polyolefins Conference and FlexPacCon 2010 February 21–24 at the Hilton Houston North. Don Witenhafer Conference Chair, Robert Portnoy Program Chair for Polyolefins, and Andy Christie Program Chair for FlexPacCon have worked extremely hard to put together a fantastic technical program and group of presenters. I want to thank our sponsors for their support and making this event such a great success. Without their support the conference and all the activities to promote the education of plastics the SPE South Texas Section would not be possible. THANK YOU!

Platinum Sponsor

PMC Group Inc. was this years Platinum Sponsor and hosted the welcome reception at the Hilton Houston North hotel. PMC Group, Inc. is a privately held global manufacturer of specialty chemicals and plastics, founded in 1994 by Dr. PM Chakrabarti, former chief of technology at PPG Industries, with a vision to create an organization capable of sustaining growth through innovation. PMC Group operates manufacturing facilities in North America, Europe and Asia. The company is headquartered in Mt. Laurel, New Jersey.

Gold Sponsors

Silver Sponsor

Bronze Sponsors
BASF
Ametek Westchester Plastics
Ribelin Sales
Amfine

The proceeds from this conference provide funding to further our mission of supporting education. The South Texas Section of the Society of Plastics Engineers provided the funding for Society of Plastics Engineers Student Sections at Lamar University, Texas A&M, University of Houston, University of Houston Downtown, Texas Tech, University of North Texas and other emerging programs in 2009-2010. In these Student sections we also provided $14,000 in scholarships to students. We are proud to promote the education of plastics in these student sections and for the work that these student sections are producing.

There are many opportunities to be involved in the South Texas local section. To serve our large geography and busy schedules each month we host a number of informal events. Our monthly technical programs are usually hosted in the evenings at the HESS Club the second Monday of the month. We have an informal breakfast the first Tuesday of each month at 7:00 a.m. on the west side and a lunch meeting the third Friday of each month in The Woodlands. This month on Friday, February 26 the SPE Young Professionals will be hosting a happy hour for networking. Information about all our events can be found on our website www.spe-stx.org. If you need more information on any events, want to volunteer in the section or have someone to personally welcome you and introduce you to others at a meeting please feel free to contact anyone in leadership listed on our website. They will be happy to help you get involved.

All the best!

Jeff Applegate
SPE South Texas President 2009-2010

Polyolefins Conference and FlexPackCon – Mark your calendars!

The 2010 International Polyolefins Conference and FlexPackCon will be held at the Hilton Houston North (formerly known as the Wyndham), Feb 22-24, 2010. 

This year’s program will again include both the traditional Polyolefins focus as well as the Flexible Packaging program. One of the themes for FlexPackCon will be sustainability and will include talks by Chet Rutledge, Director of Packaging Procurement,WalMart; Larry Dull, Partner, Packing Knowledge Group (PKG) LLC; and Victor A. Bell, President, Environmental Packaging International. They will discuss the WalMart scorecard and it’s extensions, how to used the scorecard to evaluate new opportunities, and packaging Life Cycle Analysis. FlexPackCon will also provide updates on food law (e.g. FDA) and potential regulatory expansions.

If you know of particular developments which should be presented at the conference, please contact Robert Portnoy for Polyolefins rportnoy@portnoytechnicalservices.com) or Andy Christie (andy@optexprocesssolutions.com) for FlexPackCon.  If you’d like to sponsor a coffee break or exhibit, please contact Emery Jorgenson (emery@jorgensonmachinery.com).

We look forward to seeing you at the conference!

SPE FlexPackCon 2010 Addresses Nano Layer Film Effects

As part of the SPE FlexPackCon 2010 program in Houston, Feb. 22-24, 2010, Hank Schirmer, BBS Corp., will discuss results from barrier films produced with up to 75 layers of various resins, including EVOH and COC.

Utilizing a modular die system, the researchers utilized both downward and upward extrusion to produce variants of traditional barrier films such as LDPE/adhesive/nylon/EVOH/nylon/adhesive/LDPE. They substituted up to 75 nano-layers such as PP/EVOH and COC/EVOH for the barrier core.

While the COC/EVOH films suffered from lack of adhesion between the components, they exhibited excellent optical qualities. The PP/EVOH structures were hazier, presumably reflecting the inherently higher haze of the PP and rheological issues. The researchers report no enhancement of oxygen barrier, either wet or dry, resulting from the nano-layer structure. They hypothesize the nano-layer technique may have modified the crystallinity and inherent barrier of the component resins or brittleness may have degraded layer continuity and barrier. The researchers suggest potential improvements associated with better adhesion from modifying the resins.

Other related film papers include “High Barrier, Non-Foil Packaging Materials” by Tom Dunn, Printpack, and “Value Films from Sub-Micron layers” by Gary Oliver, EDI. The 3-day FlexPackCon program will include sessions on sustainability and source reduction, recent advances in materials and converting technologies, and the impact of recent regulatory changes on flexible packaging manufacturers.

More information on the SPE FlexPackCon 2010 and International Polyolefins 2010 Conference is available at http://www.spe-stx.org/PolyolefinsConference.htm, at www.4spe.org, or by calling Lesley Kyle at 1-203-740-5452.

SINOPEC Research Executive Discusses Recent Advances in Polyolefins Technology at SPE Conference

In support of the 9.7% growth rate by the Chinese plastics processing industry, and in response to growing supply from the Middle East and other lower-cost feedstock regions, China’s SINOPEC Beijing Research Institute of Chemical Industry has sponsored major programs in polyolefin catalyst, process, additive, and product developments. These programs and their resultant technology advances will be addressed by Dr. Jinliang Qiao at the SPE International Polyolefins Conference in Houston, TX, Feb. 22-24, 2010.

Research on BOPP film and PP pipe has been completed, resulting in new catalysts and additives. SINOPEC claims their N-series catalyst (also produced by BASF and known as Lynx 1000 in the US) delivers higher isotacticity and better stability PP. The N-catalyst technology is also extended to PE as BCE and BCS catalysts for slurry and gas-phase processes. A critical success factor in these developments was lower cost. Work continues on chrome-based and single-site catalysts for PE and broad-MWD catalysts for PP.

In the area of nucleating agents, SINOPEC has developed new nucleating agents with more efficient increases in PP stiffness (as measured by flexural modulus) and crystallization temperature. They have also identified nucleating agents for toughening and clarifying PP and nucleating LLDPE. Additives have also been identified to aid in the dispersion of bacteriacides, etc.

Responding to cost pressure, SINOPEC developed higher-crystallinity TPO formulations for automotive bumpers, eliminating the need for rubber compounding. Similarly, they developed new BOPP resins designed to allow faster extrusion on wider lines producing down-gauged uniform film. Additional requirements for this BOPP program were lower extractables with fewer “fish eyes”, while accommodating reduced thickness with higher stiffness. This new BOPP resin was designed to utilize refinery propylene where ethylene is not available as a comonomer. It is produced with a patented non-symmetric donor technology.

Overall Chinese growth in GDP has supported increased demand for building and construction, leading SINOPEC to develop new PP pipe resins for hot water. Again, the developments have included catalyst programs to broaden Molecular Weight Distribution. SINOPEC extended their learnings to PE to address challenging requirements in Long-Term Hydrostatic Strength, Rapid Crack Propagation, and Slow Crack Growth. Their structure/property research focused on the conflicting demands for stiffness and toughness, for which they have developed new PE100+ products.

The research has been conducted in cooperation with the National Nature Science Foundation of China under the auspices of the National Basic Research Program and the Ministry of Science and Technology.

Dr. Qiao’s talk will be included in the plenary session of the SPE International Polyolefins Conference. Other sessions will include recent advances in catalyst technology, new process developments, new additives and polymer modification technologies, and emerging characterization methodologies. Applications sessions target packaging, infrastructure, and automotive markets.

More information on the SPE FlexPackCon 2010 and International Polyolefins 2010 Conference is available at http://www.spe-stx.org/PolyolefinsConference.htm, at www.4spe.org, or by calling Lesley Kyle at 1-203-740-5452.

http://www.linkedin.com/groups?gid=2073302&trk=hb_side_g

Join the South Texas Section of the Society of Plastics Engineers on Linked-In. Click on the above link and you will be directed to group page. Linked-In will serve as another communication tool for SPE-STX.

Linked-In  is a free web site for professional networking with over 40 million members as of May 2009.

Linked-In enables discussions and networking between SPE-STX members and those related to the plastics industry. Linked-In compliments the current SPE-STX web and membership to Linked-In is free. 

News Highlight
Linked-In SPE-STX group currently has 116 member as of 1 October. To date, the tool has been used primarily to promotes and discuss SPE-STX meetings. 

Members are also notified of meetings from board members plus email blasts sent by SPE International.  

As always, both the monthly newsletter and STPE-STX web site are the leading source of information on SPE-STX activities.  

Bulletin Board

Plastics Information: Check it Out

The Houston Public Library on McKinney has resources on plastics and polymers. Check out their catalog at www.hpl.lib.tx.us. If you are not near the McKinney location, you can arrange to pick up your books at your local branch.

The Fondren Library at Rice University has the most complete collection of books on plastics and polymers. This is also a prime resource for patent and trademark information, as well as other US Government documents. You cannot check out books there unless you join Fondren Library [$50], but you can arrange for books to be sent to your library by inter-library loan. Use their catalog at http://library.rice.edu/.

The next best place to browse is at the MD Anderson Library at the University of Houston central campus. South Texas Section has donated many plastics books to this library. If you plan ahead, you can get a TexShare library card from a library where you are a member, which will allow you to check out books from any U of H library. Their catalog is at www.library.uh.edu/.

Book Bag

	Additives for Polyolefins Michael Tolinski, 304 pages, Jul-2009 ISBN-13: 978-0-8155-2051-1 $150.00 This book focuses on the polyolefin additives that are currently important in the plastics industry, alongside new additives of increasing interest, such as nanofillers and environmentally sustainable materials. As much as possible, each chapter emphasizes the performance of the additives in the polymer, and the value each relevant additive brings to polypropylene or polyethylene. Where possible, similar additives are compared by capability and relative cost. With major sections for each additive function, this book provides a highly practical guide for engineers and scientists creating and using polyolefin compounds, who will find in this book a wealth of detail and practical guidance. This unique resource will enable them to make practical decisions about the use of the various additives, fillers, and reinforcements specific to this family of materials. Contents: SECTION I: OVERVIEW OF POLYOLEFINS AND ADDITIVES 1 Introduction 2 Trends in polyolefin & additive use SECTION II: ENVIRONMENTAL RESISTANCE 3 Antioxidants and heat stabilization 4 Ultraviolet light protection & stabilization 5 Flame-retarding additives 6 Additives for modifying electrical properties SECTION III: MECHANICAL PROPERTY ENHANCEMENT 7 Overview of fillers & fibers 8 Factors determining selection of fillers and fibers SECTION IV: APPEARANCE ENHANCEMENT 9 Colorants 10 Nucleation and clarity SECTION V: PROCESSING AIDS 11 Processing aids for molding 12 Processing aids for extrusion SECTION VI: OTHER MODIFICATIONS OF FORM AND FUNCTION 13 Reducing density: Polyolefin foams 14 Coupling, compatibilizing, recycling, and biodegradability 15 Cross-linking 16 Sterilization & radiation resistance 17 Aesthetics enhancement and surface modification SECTION VII: CONCLUSION: INCORPORATING ADDITIVES 18 Adding Additives to resin References Index
	Flame Retardants for Plastics and Textiles: Practical Applications Edward D. Weil, Sergei V. Levchik, 2009 ISBN: 9781569904541 $100.00 An overview of flame retardants that are either in commercial use or in advanced stages of market development, reviewed polymer-by-polymer, supplemented by a brief overview of mode of action and interaction. It is more of a “how-to-do-it” book than an academic study. As such, it names trademarked materials as well as products in active stages of development, gives suggestions for selecting among alternatives, provides suggested formulations, and offers a starting point for the compounder or plastics fabricator to pass commercial flammability requirements. Contents: Flame Retardants in Commercial Use or Development for Polyolefins Polystyrenes and Thermoplastic Styrene Copolymers Flame and Smoke Retardants in Vinyl Chloride Polymers – Commerical Usage and Current Developments Current Practice and Recent Commercial Developments in Flame Retardancy of Polyamides Flame Retardants for Thermoplastic Polyesters Flame Retardants in Polycarbonates and Polycarbonate Blends Commercial Flame Retardancy of Unsaturated Polyesters, Vinyl Resins, Phenolics and their Composites Flame Retardants in Commercial Use or Advanced Development in Polyurethanes Current Flame Retardant Systems for Epoxy Resins Flame Retardants in Commercial Use or Development for Textiles Comments on Flammability and Smoke Tests Overview of Modes of Action and Interaction of Flame Retardants Directory of Flame Retardant Manufacturers, Distributors, and Compounders
	Plastics Manufacturing Systems Engineering: A Practical Approach David O. Kazmer, 2009 ISBN: 9781569904626 $100.00 Plastics manufacturing is a highly interdisciplinary endeavor requiring knowledge related to materials science, physics, engineering, and management. Because of this diversity, the plastics process engineer interacts with many stakeholders, including customers, designers, materials suppliers, machine builders, mold/die suppliers, systems integrators, operators, quality engineers, and managers. With so many stakeholders involved, it isn’t surprising that many plastics manufacturing processes are not precisely engineered systems. The resulting processes can be poorly designed, requiring too much investment to achieve too little productivity. This book was written to educate and support plastics processing engineers, but is also highly useful to others involved with plastics manufacturing who are performing process development, research, and even machinery design. It uses a manufacturing systems engineering approach to provide guidance about plastics manufacturing as an integrated system with broadly applicable analysis of the underlying subsystems. Contents: Background, Plastics Manufacturing Systems, Heating and Cooling, Hydraulics and Pneumatics, Electric Drives, Process Sensors, Signal Conditioning, Data Acquisition Systems, Machine Controllers, Process Control, Process Characterization, Process Optimization, Quality Control, Automation, Statistical Labor Data, Material Properties, Unit Conversions, Matlab Primer
	Lawsuit!: Reducing the Risk of Product Liability for Manufacturers Randall L. Goodden, 2009, 359 pages ISBN: 9780470177976 $80.00 Reduce your exposure to civil lawsuits. Addressing product liability and laws in both the U.S. and internationally, this book helps product manufacturers and engineers develop and implement proactive processes that can reduce liability concerns and potential lawsuits. It discusses preventive measures in the engineering, development, and manufacturing of products and explains the procedures and processes manufacturers must have in place to reduce the likelihood of liability – as well as to provide the best defense in case of a lawsuit.
	Qualifications, Startups and Tryouts of Injection Molds W. J. Tobin, 2003, All inclusive CD $32.00 The truth is you don’t need fancy gizmos to do scientific molding. All you need is a machine where you can read the settings, an accurate weigh scale, and a computer. A universal setup guide only needs a little homework on your part to read each machine’s manual and the ability to read the settings. If you had a few days and an engineering textbook you could actually write these spreadsheets yourself! It is NOT MAGIC. This CD uses a practical, down to earth, easy to use approach to bringing a mold on-line and producing consistently good parts. CD contains both filled in tutorials showing what inputs are required and worksheets for you to fill in. CD Contents: Contents of the 90 page book. Spreadsheets in Microsoft Excel .xls files: Optimum fill calculation – the melt viscosity curve, Gate Freeze off, Cooling time, Cavity balance for multi cavity tools, Cp CpK calculator, Universal setup sheet – includes how to translate from one machine to another, a waterline map, Runner size optimization, and a calculator to determine your process window settings. Microsoft Word .doc Files: Mold Check List, Mold History / Maintenance forms. The text includes a complete explanation of the experiments to optimize your injection molding cycle. Other Topics are: Mold Maintenance – Inspection and General Maintenance, Mold hang and Mold Pull procedures, Mold Storage, Basic Chemistry, Quality Control/ Quality Assurance – Cp and CpK explained and how to use them, Sizing Sprues, Nozzles and Runners for your mold, Hard Copy of the Mold Check List, Mold History and a Data Form to fill out for the experiments, and how to calculate a process window that will allow you to adjust the process as it drifts and still make acceptable parts.
	Plastic Conversion Processes: A Concise and Applied Guide Eric Cybulski, 2009; 165 pages $70.00 Many books describe a single plastic-conversion process, like injection molding, but until now, none has described and compared several processes. This book provides a basic overview of seven conversion processes used in the industry. These processes account for more than 97% of all plastic products. Each chapter begins with a process attribute table to serve as a quick guide. The particular conversion process is then briefly described, along with a short history. To better explain each process, sections detailing equipment, tooling, and materials have been added. Also included are sections on design guidelines and on how to identify which process was used to manufacture a plastic part. Contents: Injection Molding Plastic Extrusion Blow Molding Thermoforming Reaction Injection Molding Rotational Molding Compression Molding
	Mixing and Compounding of Polymers: Theory and Practice, 2nd Edition Ica Manas-Zloczower, 2009; 850 pages ISBN: 978-1-56990-424-4 $249.00 Finally available in its second edition, this classic monograph covers everything from the basic principles to the various practical applications of state-of-the-art mixing and compounding. It discusses the basic mixing mechanisms encountered in polymer processing; the latest results in modeling, flow simulation and visualization, and scale-up rules for the most important batch and continuous mixers; the properties of various additives used in the plastics and rubber industry and their effects on the properties of the compound; working principles and practices for reactive polymer compounding; compatibilization mechanisms applicable to blends and composites; mixing practices in the current commercial mixing devices; key aspects of mixing at nanoscale; and scale-down of mixing equipment and fundamentals of microfluidics. Contents: Part I: Mechanisms and Theory Basic Concepts - Mixing of Miscible Fluids - Mixing of Immiscible Fluids - Dispersive Mixing of Solid Additives - Distributive Mixing - Distribution Functions and Measures of Mixing Part II: Mixing Equipment - Modeling, Simulation, Visualization Batch Equipment Simulation - Batch Equipment Visualization - Continuous Equipment Simulation - Dispersive Mixing Devices in Single Screw - Twin Rotor Mixers - Co-Kneader - Visualization - Scale-up of Mixing Equipment - Scale-down of Mixing Equipment Part III: Material Consideration, Properties and Characterization Solid additives (inorganic) - Solid additives (organic) - Compatibilizers (mechanisms, theory) - Material Consideration for Mixing at Nanoscale - Effect of Mixing on Properties of Compounds - Effect of Mixing on Rubber Properties Part IV: Mixing Practices Internal Mixers - Single Screw Extruders - Twin Screw Extruders - Intermeshing Twin Screw Extruders - Reciprocating Screws - Reactive Compounding - Farrel Continuous Mixer
	Injection Molding: Fundamentals and Applications Musa R. Kamal, Avram I. Isayev, S. Liu, 2009; 800 pages ISBN: 978-1-56990-434-3   $249.00 This book surveys the state of the science and technology of the injection molding process. It represents a comprehensive, balanced mix of practical and theoretical aspects for a wide range of injection molding applications. The authors of the 21 chapters are experts and leaders in their respective areas of specialization in the injection molding field. While it is not possible to cover all aspects of such a dynamic growing field, readers should find sufficient information and background to become acquainted, at various levels of depth, with key components of the science and technology of injection molding. Contents: Injection Molding: Introduction and General Background Injection Molding Machines, Tools, and Processes The Plasticating System for Injection Molding Machines Non-Conventional Injection Molds Gas Assisted Injection Molding Water Injection Techniques (WIT) Flow Induced Fiber Micro-Structure in Injection Molding of Fiber Reinforced Materials Injection Foam Molding Powder Metal Injection Molding Micro Injection Molding Internal Visualization of Mold Cavity and Heating Cylinder Injection Molding Control Optimal Design for Injection Molding Development of Injection Molding Simulation Three-Dimensional Injection Molding Simulation Viscoelastic Instabilities in Injection Molding Evolution of Structural Hierarchy in Injection Molded Semicrystalline Polymers Modeling Aspects of Post-Filling Steps in Injection Molding Volumetric and Anisotropic Shrinkage in Injection Moldings of Thermoplastics Three-Dimensional Simulation of Gas-Assisted and Co-Injection Molding Processes Co-Injection Molding of Polymers
	ANTEC™@NPE 2009 Conference Proceedings - Thumb Drive SPE, Chicago, Illinois USA, June 2009, Thumb Drive $250.00 In Chicago in 2009, ANTEC® (Annual Technical Conference), sponsored by the Society of Plastics Engineers, celebrated its 67th year of excellence. The largest peer-reviewed technical conference serving the plastics industry, ANTEC® is perfectly positioned to help the plastics specialist achieve new levels of professional development. Order the ANTEC® 2009 proceedings on thumb drive or CD-ROM. Includes 700+ papers detailing the latest developments in: Alloys and Blends, Applied Rheology, Automotive, Biopolymers, Blow Molding, Color and Appearance, Composites, Decorating and Assembly, Electrical and Electronic, Engineering Properties and Structure, Extrusion, Failure Analysis and Prevention, Flexible Packaging, Injection Molding, Joining of Plastics and Composites, Marketing and Management, Medical Plastics, Mold Making and Mold Design, Nano/Micro Molding, Plastic Pipe & Fittings, Plastics in Building and Construction, Plastics Environmental, Polymer Analysis, Polymer Modifiers and Additives, Process Monitoring and Control, Product Design and Development, Radiation Processing of Polymers, Rotational Molding, Thermoforming, Thermoplastic Elastomers, Thermoplastic Materials and Foams, Thermoset, and Vinyl Plastics.
	Injection Molding - Thumb Drive SPE, Chicago, Illinois USA, June 2009, Thumb Drive $50.00 Injection Molding Titles Include: Optimizing the Molding Process — Chapter from Plastics Technician’s TOOLBOX, by Jerry Golmanavich, Golmanavich Enterprises Shear Induced Imbalances and MeltFlipper® Technology, by John P. Beaumont, Penn State Erie & Beaumont Technologies, Inc. The Warpage Simulation with In-mold Constraint Effect in Injection Molding, by Dr. Venny Yang, CoreTech System Co., Ltd. The Investigation of Flow Behavior of Polymeric Melts in Water Assisted Injection Molding, by Dr. Chao-Tsai Huang, CoreTech System Co., Ltd. Injection Molding of Woodfiber Plastics Composites, by Michael Burgoyne State of the Art of Electric injection Molding, by M. Barr Klaus, Electric Injection Services, Inc. Mold Ejector Pin Melt Flow Volume Sensor, by Fred Buja, FjB PlasTechnology Water up to 400°F – The Best Way To Heat up Your Mold, by Anna Birkhofer, consultant Asia Tooling and Molding: How To Be Successful, D.B. "Dusty" Rhodes, Waypoint Bellwether, Inc. It Is as Easy To Be an Injection Molding Compounder as It Is To Be an Injection Molder, by Peter Lipp, Krauss-Maffei Corporation Effect of Injection Molding Process Parameters on the Morphology and Quality of Microcellular Foams, by Jingyi Xu Microcellular Injection Molding of Polylactide-Montmorillonite Nanocomposites, by Sarah Gong, Assistant Professor, University of Wisconsin-Milwaukee

SPE-STX Board Meeting

Location: by Teleconference
Date: January 12, 2010

Selection of Colorants and Other Additives for Durable Products

James J. Bal
Ferro Corporation
Engineered Plastics Products
Stryker, OH

Abstract

Polyolefins are utilized frequently in durable products that call for extended life in a variety of environmental conditions. Many of these products require color and almost all require and enhanced degree of resistance to the stresses of an exterior environment. The selection of plastic colorants that can withstand harsh environmental conditions is critical to ensuring the long term appearance of a polyolefin based durable product. Likewise, the correct choice of plastic additives for exterior applications must be made in order to ensure acceptable product appearance and performance over time.

This paper examines key design considerations for durable polyolefin products in terms of additive selection. Special consideration is made in terms of selecting colorants that are considered non-toxic. A practical example is presented.

Background

Polyolefins, and in particular polyethylene and polypropylene, are the most widely utilized plastics in the world today. The blend of a robust mechanical and physical properties palette, excellent chemical resistance, and reasonable cost for this polymer class makes it a prudent choice for use in most durable goods applications. Specifically, polyolefins are an excellent choice as a material to use in applications that require extended exposure in outdoor conditions. Polypropylene and polyethylene are routinely utilized in the manufacture of such items as refuse containers, play equipment, decorative shutters, and recreational vehicles.

Outdoor durables encounter a wide variety of material stress brought on by exposure to the environment. Weather conditions vary around the world so upfront design of a polyolefin durable (herein referred to as durable) sufficient to perform in various climates if often required. The main components of the weather that cause degradation of any polymer are temperature, moisture, wind, dust, pollutants, and sunlight [1].

A durable will have a surface temperature resultant of several factors including the surface finish, color, heat capacity, and thermal conductivity of the material used to make the durable. A decrease in thermal oxidative stability over time can result from consistently high surface temperatures. Frequent exposure to precipitation and high humidity can accelerate the deterioration of the surface of a durable. Wind transfers dust and pollutants that cover the surface of a durable. While some limited protective effects from particulate coatings exist, some dusts and volatile pollutants like sulfur dioxide can initiate or catalyze chemical reactions on a durable.

Much has been written about the effects of ultraviolet (UV) radiation on polymeric material and in particular polyolefins. While UV radiation still comprises a relatively small portion of the total radiation found in sunlight that reaches the earth’s surface, the acceleration of the deterioration in the earth’s ozone layer over the last several decades dictates that subsequently outdoor durables will be exposed to even higher doses of UV radiation than previously realized.

Though polyolefins are suitable polymers to use in outdoor durable applications they must be used in concert with weatherfast, heat resistant colorants to maintain color. Dyes are not recommended for use in polyolefin applications because they will be soluble and migrate out of the matrix.

Most inorganic pigments meet the required performance criteria for durable applications. These colorants are also chemically stable in general and are insoluble in polyolefins so they will not migrate. Their drawbacks include inferior intensity and brightness in comparison to organic pigments of the same color.

Some organic pigments can effectively be used in durable applications. The fastness properties of organic pigments vary widely so care must be taken in selecting types that meet exposure thresholds. Organic pigments will usually have greater color strength and brightness than the inorganic varieties due to the organic pigments relatively larger surface area and higher molar extinction coefficients. Solar radiation absorbed on the surface of organic pigments will eventually lead to the deterioration of the pigment. The nature of the chemical bonds in organic pigments is what makes them more susceptible to photodegradation than inorganic pigments. In most instances the higher the degree of surface area the quicker the deterioration of the organic colorant [2].

It is helpful to review some of the specific pigment types suitable for use in polyolefin durable applications.

The carbon black colorants are the best pigments for improving the long term performance of an exterior durable. Besides providing a pristine black color, carbon blacks also absorb all light and impede the detrimental effect of UV radiation on durables. Carbon blacks are also effective anti-oxidants, helping to prevent oxidation of durables in environments with long term heat exposure.

Titanium dioxide is the most widely used white colorant. The rutile crystalline form is preferred over that of the anatase form in durable applications since the former has a higher refractive index that results in better opacity or hiding strength. The rutile form has better weathering properties as well. A surface treatment can improve these weathering properties and prevents yellowing of the titanium dioxide in the presence of phenolic antioxidant additives [3].

Titanium dioxide strongly absorbs light in the near-UV portion of the spectrum (200 nm – 380 nm) so it does provide some degree of protection for a polyolefin matrix. Barium sulphate, zinc sulfide, and antimony oxide are examples of other inorganic white colorants that can be utilized in durables. These pigments are often utilized since they effectively reflect light in the ultraviolet region.

Inorganic pigments suitable for exterior durable applications in the blue to green color space include ultramarine blue, cobalt aluminates, and chrome oxide. Special care should be taken in the use of ultramarine blue pigments in durable applications as these colorants have poor chemical resistance in environments where acidic pollutants are present. In the organic pallet, copper phthalocyanine blue and green pigments are commonly used in exterior application since they are found to have good weatherfastness properties. They are also relatively inexpensive when compared to the inorganic blue and green pigments.

Many plastics converters prefer to utilize colorants other than those that present potential health hazards. Colorants of these types are commonly restricted by legislation that limits their use. Many of the most weatherfast and heat stable inorganic pigments contain significant levels of heavy metals, specifically hexavalent chromium, lead, mercury, and cadmium, so that the benefits derived from using them in custom color applications is offset by the extra measures required to ensure safe handling and disposal in converters’ production facilities.

Chromate yellow and orange pigment types generally exhibit excellent fastness and provide bright, strong shades of color in durables. However, legislation restricting their use in only applications where the pigments are deemed essential to end use performance makes them undesirable in most cases. More recent pigment technology, the synthetic rare earth pigments like cerium sulfide fill the same color space, have no toxicity concerns, and deliver the same fastness properties as the chromates.

Iron oxide and mixed metal oxide pigments can also be used in place of the heavy metal pigments. These colorants come in various colors from yellow and green to red as well as black and brown. Synthetic versions of these inorganic pigments are most often used as the purity and physical form can be controlled to a larger degree. These pigments demonstrate excellent durability and UV screening capabilities. They typically cost less than the lead based pigments and in comparison have very few toxicity concerns making them suitable colorants for durable applications.

Though the mixed metal forms show improved color strength and brightness over some of the basic iron oxides, the major drawback of all metal oxide inorganic pigments is their low color intensity and relatively dull appearance, which cannot be compensated for by higher dosing.

Organic colorants such as diaryl pyrrolopyrrole (DPP) pigments and in particular Pigment Red 254 are commonly used in high performance durable applications that call for bright, chromatic colors. Pigment Yellow 120 (a benzimidazolone pigment) and Pigment Orange 43 (a perinone pigment) have shown to be suitable in some durable applications as they exhibit a higher degree of light and weatherfastness over other organic pigments of the same color space. Since the mid-1950’s, the quinacridone family of organic pigments have been a staple in color matching for durable applications. General characteristics of this group of pigments include good heat resistance and light stability.

Matching a custom color for a durable application may require blending several of the pigment types mentioned above. A manufacturer of custom colors for polyolefin durables must keep the fastness and heat resistance performance of all components in mind when formulating. Studies show that the use of higher concentrations of pigment is beneficial and improves the light stability of polyolefins, but this depends upon the type of colorants used. Pigment levels should be optimized via the color matching process and subsequent performance evaluation in order to ensure that enough colorant is present to aid in confining UV absorption to the immediate surface of the durable. [4]

Polyolefins are intrinsically unsuitable for outdoor durable applications since the will easily photo-
oxidize in exterior conditions. However, their combination of low cost, ease of processing, and recyclability continues to promote research into effective methods of photo stabilization of polyolefins. Adequate pigment levels will afford some protection from UV radiation to the host polyolefin. UV stabilizers and antioxidants, however, need to be added to the durable in order to ensure long term performance in outdoor environments. There is usually negligible to no protection of colorants from photo degradation with these same polymer additives.

A full discussion of the mechanisms by which various light stabilizers and anti-oxidants protect a polyolefin durable matrix is beyond the scope of this paper. However, much has been documented regarding the effectiveness of the sterically hindered amine light stabilizers (HALS) in polyolefins. A combination of low and high molecular weight HALS has shown to be particularly effective [5]. Likewise, the synergy between such a UV stabilizer combination and long term heat stabilizer additives such as a phenolic anti-oxidant can ensure a durable performs through its expected life cycle.

Example

The color requested was a bright golden yellow for use in an injection molding grade of high density polyethylene (HDPE). Color was to be supplied in a concentrate form, no greater than 4% by weight of the end part. The end application was body panels for recreational vehicles. The end parts could have anywhere from very light to heavy exposure to exterior conditions over the lifetime of the vehicle.

Several color match trials were completed over the course of a month (see Table 1 for individual trial sample components). The initial match (04-106) contained two yellow pigments. Pigment Yellow 109 and Pigment Yellow are both advertised to have good fastness properties in polyolefins. The 04-106 sample also contained titanium dioxide and a standardized stabilizer package found to be suitable for other colors in the same application. This initial match had an unacceptable cost associated with it.

In order to attempt to reach an acceptable cost, Pigment Yellow 109 was substituted with modified Pigment Yellow 183, an azo pigment. This pigment was advertised to have good fastness properties in HDPE and costs less than Pigment Yellow 109. The initial color match with P.Y. 183 resulted in a sample (04-108) with adequate color but insufficient opacity. Pigment levels in 04-108 were increased to match the opacity of the 04-106 sample. This resulted in a sample (06-107) that ended up with approximately 40% more pigment than that found in 04-108.

A variant of the 04-106 sample with increased UV stabilizer (HALS-1) was created to check the efficacy of the standardized stabilizer package. A variant of the 04-108 sample with a modified UV stabilizer package 04110 was created to check for any pigment-stabilizer synergy. A second type of UV stabilizer was added to the 04-110 sample (HALS-2). The HALS-2 additive is a lower molecular weight species.

All samples were evaluated in an Atlas Ci65 xenon arc weatherometer to check for weatherfastness in an accelerated test. The test method selected was SAE J1960, a method commonly used in the evaluation of automotive exterior parts. Samples were inspected at intervals of 500 kJ/m² until a color shift within sample sets was discovered. At that point, one sample from each sample set was recovered from the xenon arc at every 500 kJm• up to 2500 kJ/m². Figures 1 through 4 exhibit the appearance of sample sets at 0, 1500, 2000, and 2500 kJ/m• exposure.

Color shifts were measured on a color spectrophotometer. The resultant CIELab color values and observations from sample inspection can be found in Table 2.

Several points can be made upon review of the test results:

• P. Y. 109 is much more weatherfast than the modified P.Y. 183.
• The weatherfastness of the P.Y. 183 sample set containing a higher dose of pigments is better than of the sample set with 40% less pigment.
• The standard stabilizer package developed for the application is not quite suitable for the gold yellow color in the same application.
• The addition of more HALS to samples with P.Y. 183 did delay degradation of the test specimen’s surface but had no perceived effect on the weatherfastness of P.Y. 183.

Summary

This paper has examined some basic design considerations for coloring and stabilizing exterior durable applications where polyolefins are to be utilized as the bulk component. There is a large palette of colorant chemistries to choose from, each with positive and (potentially) negative features. Special care must be taken when selecting pigments for a custom color blend so that the final color will meet all lifetime performance criteria for a specific durable. Adequate levels of pigment in a durable polyolefin matrix can provide some protection from the negative effects of exposure to ultraviolet radiation, but addition of UV stabilizers and anti-oxidants should be considered a requirement for extended exposure.

Acknowledgements

The author wishes to acknowledge Mir L. Ali and Dr. Richard Abrams of the Ferro Corporation for their contributions and support.

References

1. Davis, A.; Sims, D. Weathering of Polymers. Applied Science Publishers, London, 2 (1983).

2. Jaffe, E.E. “Organic Pigments.” Encyclopedia of Chemical Technology, Fourth Edition, Volume 19, Kirk-Othner, John Wiley & Sons, Inc., Hoboken, 51 (1996).

3. Christie, R.M. “Pigments for Plastics.” Plastics Additives: An A-Z Reference, G. Pritchard, ed. Chapman & Hall, London, 491 (1998).

4. Davis, A.; Sims, D. Weathering of Polymers. Applied Science Publishers, London, 122 (1983).

5. Zweifel, H. Stabilization of Polymeric Materials. Springer-Verlag, Berlin, 83 (1997).

Key Words

Pigment, polyolefin, UV, stabilizer.