Study Shows SUS Reduces Carton Deformation During Typical Freeze/Thaw Cycles

Marietta, GA - As a provider of coated unbleached kraft paperboard in the industry, Graphic Packaging International, Inc. has conducted extensive product comparison studies to assist consumer products companies in determining how to minimize carton deformation and compression damage through selection of appropriate paperboard materials for frozen food applications. The research compared performance across leading paperboard product lines and determined Graphic Packaging International's coated unbleached kraft, sold under the brand name SUS, outperforms other paperboard substrates and corrugated products.

Illustrating the impact of typical handling in a retail setting, the tests provide great insight into how conditions could impact paperboard performance and ultimately the consumer's decision to purchase frozen products. Consumer perception of frozen food quality is affected by carton appearance. When handled by consumers in retail stores, frozen food cartons should not feel damp or soft, and should not have crushed edges or a wavy surface. These defects can create the perception that the frozen food has thawed, giving rise to consumer concern over food safety and therefore reducing purchase motivation. Such defects are often the result of condensation that occurs due to temperature changes during the distribution process and in the retail freezer case. Moisture absorbed by paperboard can soften and buckle the carton.

Utilizing a unique carton profilometry device developed by Graphic Packaging International, the company performed extensive tests to measure resistance to carton deformation as characterized by the degree of buckling occurring in the top carton panel after the carton was exposed to a series of freeze/thaw cycles similar to those experienced by the carton as it moves from the filling line through the distribution chain to the retail freezer case. The freeze/thaw cycling results in a several percent moisture increase, an associated decline in carton stiffness and compression strength, and varying degrees of main panel buckling.

The carton profilometer uses a non-contacting laser, and data is analyzed by a computer which generates a topographical image of the top carton panel. Using the profilometry machine, Graphic Packaging International conducted controlled experiments to measure competitive packaging against SUS, rendering these results:

• In identical structural designs, cartons produced from SUS exhibited less peak-to-peak deformation than the same carton produced with recycled freezer grades, and also exhibited less welting
  
• SUS exhibited less peak-to-peak deformation than SBS

In addition to profilometry testing, Graphic Packaging International also conducted compression testing pre and post freeze/thaw, with compelling results:

• A test of structurally identical 14 pt. cartons indicated that the cartons made from SUS retained 56 percent of their compression strength, compared to a 47 percent retention rate for cartons produced with a leading SBS grade when cartons were exposed to controlled freeze/thaw cycles.*
  
• In testing a second structural design in two calipers, cartons produced from 14 pt. SUS retained 72 percent of their strength, as compared to 16 pt SBS cartons' 66 percent retention under similar conditions.*
  
• With new capacity coming out of Latin American competitors, Graphic Packaging International also tested short span compression strength (STFI) between one of these players and SUS. SUS retained more than 75 percent of its short span compression strength, MD and CD, after freeze/thaw cycles, while the Latin American competitor's product averaged around 60 percent retention.
  
• SUS exhibits significant advantage in compression strength over recycled grades both pre and post freeze/thaw conditioning.

"Recent industry tests confirm what our customers have known for years," said Jim Monahan, vice president of sales and marketing for North American open market paperboard for Graphic Packaging International. "Our substrate is superior in the industry, as evidenced by our 25 percent market share of paperboard used for frozen food packaging in the United States, including 85 percent of all frozen pizza tonnage and 60 percent of all frozen bakery products." With over 22 percent of the market in U.S. folding carton sales, Graphic Packaging International is also the number one supplier of coated unbleached kraft (CUK) in the world.

SUS's strength and durability is attributed to its composition, which is primarily pine fiber. The length of pine fibers make the product much stronger than other, shorter types of fiber used to make other substrates. The unique three-ply construction of SUS folding carton grades enables the product to achieve superior resistance to compression and bulging, with the added benefit of hiding coating flakes in the interior ply so that the back of the board is blemish free. SUS is "hard-sized" to provide good moisture resistance, and natural resins in pine fibers further aid in water resistance.

"This validation of the industry's selection of Graphic Packaging International's SUS as the industry leader reinforces the success of our commitment to driving efficiency and revenue for our customers," said Bob Spiller, senior vice president of performance packaging division at Graphic Packaging International. "Our customers not only value the strength and durability of our products, they also factor into their buying decisions comparable print quality, excellent packaging line efficiency, environmental and cost benefits of our non-poly products, and the ability to reduce caliper relative to other grades."

Demand for stronger, more durable packaging has also enabled Graphic Packaging International to expand its Z-Flute offering into club stores, replacing traditional fluted packaging with a product that not only adds to production efficiency but also offers reliable packaging that provides significant distribution performance accompanied by higher speeds and greater throughput. These attributes, along with the high graphic capabilities Z-Flute offers, have resulted in Z-Flute sales doubling each year since its launch, due largely to the industry's desire to identify high-performing packaging products, such as Z-Flute, as more durable alternatives for mini-flute products in order to ensure greater reliability and more predictable performance.

Further studies show Graphic Packaging International's Z-Flute demonstrated superior compression performance when tested against comparable products. Composipac Z-Flute not only retained greater compression strength following freeze / thaw cycles, but demonstrated an increase in strength. Whereas comparable B Flute retained 40 percent of its compression strength, thereby reducing the safety factor of the carton, Z-Flute had retention of 90 percent or greater. **

With significantly more consistent, reliable performance under standard freeze/thaw cycles and high humidity conditions, the success of this relatively new packaging product has further solidified Graphic Packaging International's leadership position.

Graphic Packaging International's high-performance products support the successful marketing of customer's brands, providing durable, quality products that ensure that at point-of-sale, consumers experience quality packaging that reflects the quality of the products they are purchasing.

Testing Conditions

• Freeze/thaw tests consisted of five, one-day cycles with 23 hours at 0 degrees Fahrenheit and one hour at 39 degrees Fahrenheit, with 90 percent RH as the "thaw" cycle.
  
• Freeze-Thaw cycling consisted of 5 cycles: 12 hour at 0 degrees Fahrenheit, followed by one hour at 37 degrees Fahrenheit, 90 percent RH (i.e. moisture condensing)

SOURCE: Graphic Packaging International