A Comparison of Folding Carton Substrates and Appropriate Applications

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A Zumbiel White Paper A Comparison of Folding Carton Substrates and Appropriate Applications In today s packaging landscape, the choice of raw materials can be daunting.

1 A Zumbiel White Paper A Comparison of Folding Carton Substrates and Appropriate Applications In today s packaging landscape, the choice of raw materials can be daunting. Substitutions are sometimes made with little or no regard to suitability; nonetheless, the differences in paperboard properties and appropriate applications are creating some interesting nuances in today s recovering economy. The choice of substrate is influenced by a number of key parameters, including the requirements of print performance, product protection, design features and requirements, sustainability and overall value. Folding Carton Considerations Print Performance and Product Protection A key object for paperboard packaging is print performance. Traditional print technologies such as sheet and web offset lithography, flexography, and rotogravure are being supplemented by digital printing, laser imaging, ink jet and rotary screen. It s a modern miracle that packaging substrates can and do perform suitably with each of the processes. Inks and overprints may be aqueous, solvent based, oil based and so on. They may cure by a variety of mechanisms, e.g., oxidation/ polymerization, UV, IR, EB, etc. Finally, it s interesting to note that packaging solutions often employ more than one printing process in a single package. Product protection is important since the contents as well as the package itself must survive the rigors of distribution through filling, packing, palletizing, transportation, retail and consumer handling. Damaged packaging can result in unsalable products, which takes an enormous toll on profitability. Dry and frozen foods, personal care products, beverages, pharmaceutical, automotive, hardware, toys and electronics all require differing sorts of protection temperature, shock resistance, barriers for water, humidity, bleach, alcohol, grease, blood, oxygen and so on Gateway Blvd., Hebron, KY 41048

2 Design Features and Requirements The choice of substrate can be greatly influenced by the size and style of the primary package. Panels, windows, opening, closure, filling line requirements, end use and end-of-life scenarios may favor one material over another. The grain orientation of a package is also influential, since properties such as stiffness and tensile strength are favorable in the one direction, whereas tear strength excels in the opposing direction. The proportional differences depend on the type of fiber, density and forming method of each material. Sustainability and Overall Value Sustainability is increasingly important in packaging substrate decisions. While paperboard packaging may represent less than 5 percent of a product s overall carbon footprint, it is perceived to be much more than that. Indeed, 60 percent of all packaging in the U.S. is ultimately landfilled, and initiatives such as packaging scorecards and extended producer responsibilities are raising the bar. Factors such as the use of certified fiber, renewable materials, recycled content, recyclability, biodegradability, compostability, package-to-content weight ratios and cube utilization are all tied to these decisions. 1, 2 Overall value can be defined as the expectation of benefits gained for the price paid. 3 Sustained value can be described as the customer s willingness to specify, utilize, pay for and reorder a given level of quality or service at a given price. Low-cost materials and packaging solutions are acceptable for some lower margin product categories but would be unacceptable for others. So, with these considerations in mind, an introduction to the types of paperboard follows, including: Solid Bleached Sulfate, Coated Unbleached Kraft, Coated Recycled Board and Uncoated Kraft Boxboard. Types of Paperboard Solid Bleached Sulfate In North America, Solid Bleached Sulfate (SBS) is a prominent packaging material. Made from mostly hardwood, first-generation, chemically pulped fibers are subsequently bleached, refined and formed in one ply on fourdrinier-type paperboard machines. SBS is white on both sides and throughout the sheet. The relatively short hardwood fibers are coated and polished, creating an impressively smooth print surface that accommodates the highest quality imaging by offset, flexography and gravure. This ultra-smooth surface also forms an ideal foundation for film and metallized foil lamination. Most SBS products are coated one-side only (C1S), but some may be partially or fully coated on the back side as well (C2S). SBS generally performs well for embossing, gluing and high-speed filling. It cuts cleanly and has sufficient internal and surface strength properties to accommodate high-speed printing with tacky oil-based lithographic inks. SBS is often higher priced as compared with other paperboard substrates. SBS is not known for tear strength, but generally has good stiffness and compression strength. It may be susceptible to yellowing over time with exposure to white light. It is traditionally the first choice, however, for high-quality graphics in personal care packaging, medical, pharmaceutical, confectionery, media and tobacco packaging. The pristine white back side and internal characteristics are preferred by purists for bakery and other such products involving direct food contact. Primary North American suppliers of SBS include International Paper Company, MeadWestvaco (MWV), Georgia Pacific, Evergreen Packaging, Clearwater, Rock-Tenn and Tembec. 2 Zumbiel Packaging A Comparison of Folding Carton Substrates and Appropriate Applications

Coated Unbleached Kraft Coated Unbleached Kraft (CUK) is also made from mostly first-generation, chemically pulped fibers on fourdriniertype paperboard machines.

3 Coated Unbleached Kraft Coated Unbleached Kraft (CUK) is also made from mostly first-generation, chemically pulped fibers on fourdriniertype paperboard machines. However, this substrate is formed in two or three layers and is mostly comprised of longer softwood (pine) fibers which contribute to strength. A thin concentration of hardwood fibers is added to the top surface for somewhat enhanced smoothness. CUK is mostly known for durability and resistance to tear. It is white on the top side due to its extremely opaque, titanium-based coating and otherwise brown throughout the sheet. It s somewhat less expensive than SBS. CUK is safe for direct food contact and performs well in frozen food applications. It is commonly used for packaging large, club-store, multi-pack cereals. A wetstrength version of this grade is used for the packaging of brewery and soft drink bottles and cans, where the paperboard retains 90 percent of its dry tear strength when exposed to saturated, wet conditions. A general folding carton version of this grade is well suited for frozen foods, snacks and cookies, multi-pack pudding cups, automotive, electronics and sports equipment applications requiring superior tear, tensile and compression strength in a relatively dry environment. Primary North American suppliers of CUK include Graphic Packaging and MeadWestvaco (MWV). Coated Recycled Board Coated Recycled Board (CRB) also known as clay-coated news, is a dominant material in North America and elsewhere in the world. CRB is generally made from a blend of recycled, newsprint, old corrugated containers and mixed secondary paper. Its fibers are often 100 percent recycled, with 35 percent or more of the content considered post-consumer. It is comprised of as many as eight or more layers of material, with the top ply made of bleached or semi-bleached fibers. A variety of machines is used in its manufacture, including fourdrinier, cylinder and hybrid forming systems. CRB is the most common substrate for low-cost folding cartons when recycled content is preferred or required. It is often used for single-pouch cereal boxes and other multi-purpose packaging where tear strength and premium print quality aren t paramount. It is not always used in direct-food applications, although food-grade versions of CRB are not uncommon. It often has a onedirection stiffness advantage that can be beneficial for bulge resistance in the packaging of granular products such as rice, pet foods, pancake mix and powered laundry detergent. The specification tolerances of CRB are somewhat less stringent than with SBS and other virgin grades. It is often not as strong and tends to carry slightly higher moisture content than other grades. CRB is more absorbent than SBS and CUK, and therefore requires a slightly thicker ink film and/or stronger inks to achieve a given strength of color. As with all other materials, die cutting, creasing conditions should be adjusted to optimize its performance. Primary North American suppliers of CRB include Graphic Packaging, Rock-Tenn, Cascades, Paperworks, Strathcona, Caraustar, White Pigeon and The Newark Group. Zumbiel Packaging A Comparison of Folding Carton Substrates and Appropriate Applications 3

4 Uncoated Kraft Boxboard Uncoated Kraft Boxboard (UKB)is the final grade to be considered in this discussion. Similar to Coated Unbleached Kraft, UKB is comprised of mostly firstgeneration, chemically pulped pine fibers. It is similarly formed on a fourdrinier-type paperboard machine in two layers, where the top layer houses a concentration of hardwood fiber for somewhat enhanced smoothness. Since it s uncoated, however, UKB can be a cost-effective alternative to coated paperboard with applications that appreciate an environmentally friendly, natural brown surface. It is lower in density than other grades; therefore, cartons of equal caliper weigh less. A sturdy material, UKB is safe for direct food contact. It can be reasonably printed by offset, flexo or gravure and performs well in embossing and foil stamping. The quality of graphic reproduction doesn t match that of coated materials; however, designers are sometimes creative with the earth-tone appearance. An interesting technique is to press-apply a white pigmented spot color in certain areas, then build process color on top of that. UKB is a popular choice for institutional food packaging, lawn and garden, hardware, sporting goods and other durable packaging needs. A primary North American supplier of UKB is Kapstone Charleston Kraft. Rock-Tenn produces an alternative product that is made from 100 percent recycled old corrugated containers. Hybrid materials also exist. Some CRB products may have a brown kraft back side, hence the term Coated Kraft Back (CKB), or a white layer of fiber on the back side. Mechanically pulped (groundwood) fibers may team up with chemically pulped fibers, and varying percentages of recycled fiber content are now seen with some of the grades. Nonetheless, it is incumbent on package designers to understand the effect that these treatments may lend to the performance characteristics of the various grades. In every situation, adjustments must be made in the printing, cutting, creasing, gluing and filling line conditions to optimize performance given a substrate substitution. Primary North American suppliers of CKB include Graphic Packaging and Rock-Tenn. White-back CRB is produced by Rock-Tenn. Groundwood fibers are employed in some products produced by Tembec. The choice of substrates can be summarized in a decision matrix as follows, understanding that these are guidelines only. Creative license allows for some products to play the field. For example, bar soaps have been successfully packaged in all four materials, and sometimes utilizing the back side of a material as the outward facing side opens up a new world of possibilities. 4 Zumbiel Packaging A Comparison of Folding Carton Substrates and Appropriate Applications

5 Decision Matrix Grade SBS Solid Bleached Sulfate CUK Coated Unbleached Kraft CRB Coated Recycled Board UKB Uncoated Kraft Boxboard Fiber virgin bleached hardwood, one or two coated sides 90% unbleached virgin pine, 10% hardwood kraft fiber, coated one side 100% recycled fiber, bleached top, many (5 9) plies, coated one side approx. 85% virgin pine, 15% hardwood kraft fiber, uncoated Appearance clean white natural back side grey back side natural, earth-tone appearance Common Applications personal care, medical, pharmaceutical, confectionery, media, tobacco frozen foods, dry foods, beverages, multi-packs, automotive, electronics, sporting goods, filter frames multi-purpose, setup boxes, breakfast cereals, dry foods, toothpastes, snack crackers, facial tissues, pancake mixes, powdered laundry detergents institutional food packaging, lawn and garden, hardware, sporting goods Print Quality very smooth surface, high printability by offset, flexo and gravure smooth surface, good printing by offset, flexo and gravure acceptable surface, good printing by offset and flexo less smooth, but reasonable printing by offset and flexo Calipers 8 24 pt pt pt pt. Basis Weights lbs/msf lbs/msf lbs/msf lbs/msf Density (approx.) 1 X 1 X 1.03 X.73 X Converting excellent cutting very good cutting adequate cutting good cutting Strength moderate strength highest strength acceptable strength high strength Cost (approx.) 1.2 X 1 X.8 X.8 X Sustainability renewable resource, certified fiber renewable resource, up to 17% total recycled content, certified fiber renewable resource, 100% recycled content renewable resource, reduced weight, certified fiber Selection Criteria: Cost, quantity, appearance, strength, environmental perception, finish Zumbiel Packaging A Comparison of Folding Carton Substrates and Appropriate Applications 5

Written By: Dan Malenke Dan Malenke is an accomplished training manager, with extensive coast-to-coast and international experience in developing and directing technical seminars for the printing and

6 Written By: Dan Malenke Dan Malenke is an accomplished training manager, with extensive coast-to-coast and international experience in developing and directing technical seminars for the printing and packaging industries. His career includes 20+ years with a Fortune 500 company, nine years of university teaching experience and accumulated work in production. About Zumbiel We are Zumbiel Packaging, one of the largest privately held paperboard packaging producers in the United States. In our $400 billion industry, we know that your package is often the most important contact with your customers; it must convey your values as well as inspire and energize your brand. Our team of skilled and extensively trained associates is dedicated to providing you with unique packaging solutions that meet your needs and budget. With more than 167 years of experience, Zumbiel stands ready to meet your packaging challenges. For more information, please contact Zumbiel at sales@zumbiel.com or References 1) Life Cycle Assessment results 2) Greenliving: United States Recycling Statistics 3) Wikipedia For more information, please contact Zumbiel at sales@zumbiel.com or Gateway Blvd., Hebron, KY WP-1002 July 2012

248 FOOD PACKAGING TECHNOLOGY

248 FOOD PACKAGING TECHNOLOGY the sheet. This is known as surface sizing. It improves the strength and finish of the sheet and anchors the fibres firmly in the sheet. Squeezing the sheet through a series