The Abc's of Folding Carton Substrates

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THE ABC‘S OF FOLDING CARTON SUBSTRATES

The type of paper substrate used to resulting in a sheet with less in degradation of the bonding construct a folding carton greatly strength and greater flexibility capabilities of fibers, which can influences the structural integrity, than standard corrugated board impact gluability. graphics quality, cost and other but still greater strength than characteristics of the finished paperboard. However, small Pulping Process. There are two packaging. This article explains flute corrugate is generally more primary pulping processes: the main paper substrates used in expensive than paperboard. As a chemical and mechanical. folding carton packaging, as well as result, small flute corrugate is Chemical pulping results in their characteristics and primary often used in high-end packaging shorter paper fibers than uses. in which rigidity and strength are mechanical pulping. As a result, required. chemical pulping of a given wood type will provide a smoother, A paper substrate is the raw higher-quality printing surface material used to make folding Next we discuss the different than mechanical pulping of the carton packaging. There are two factors that influence the same type of wood. However, types of substrates used in characteristics of first paperboard the longer fibers produced by the folding cartons: paperboard and and then small flute corrugate. mechanical pulping process are small flute corrugate. stronger and more durable than

Paperboard is a general term FACTORS fibers from a chemical pulping process, all other factors being describing heavier-weight grades INFLUENCING of paper (at least .01 inches thick) held constant. PAPERBOARD made from cellulose, or wood, fibers. The most common CHARACTERISTICS Wood type. The relative softness substrate used in the production or hardness of the wood used in a of folding cartons, paperboard is A number of factors influence the pulp also affects a paper also used in making boxes, characteristics of paperboard, substrate’s printing surface and shipping containers, construction including virgin vs. recycled strength. Softer woods, such as materials and other consumer material content, the process used pine, have longer fibers that and industrial products. to produce the paper pulp, the produce stronger, more durable type of wood used, whether or substrates than those produced Small flute corrugate consists of a not paper fibers have been from hard wood fibers. However, fluted, or wavy, layer of paper bleached, caliper and grain the shorter fibers from hard and one or more thin layers of direction. woods, such as oak, produce paperboard. The fluting is smoother printing surfaces. smaller than what is found in Virgin vs. recycled material content. corrugated shipping boxes, Each time a fiber is recycled it is Bleaching. Bleaching is used to shortened and, remove color from wood pulp. potentially, As a result, bleached fiber contaminated. provides a clean, white As a result, appearance throughout the sheet recycled fibers for high quality printing. have less However, the bleaching process strength and degrades and weakens wood less stiffness (in fibers, having some effect on the the cross strength of a substrate. The direction) than bleaching process also adds cost virgin fibers. In to the production of a paper addition, substrate. recycling results

Caliper and grain direction. The These factors result in a variety of thickness, or caliper, of substrate options from which paperboard is measured in thousandths of an inch, manufacturers and users of commonly referred to as folding cartons can choose. We “points.” Most paperboard is next discuss the different types between 10 points and 40 and uses of the major substrates points. Paperboard also has a available for folding cartons. “grain direction” and “cross direction.” The grain direction is the direction in which TYPES AND USES OF paperboard is machined at the are what allows it to be converted SUBSTRATES mill; the cross direction is 90 on folding carton equipment. degrees to the grain direction. There are four main types of Single-face vs. single-wall substrates used in folding cartons: construction. Small flute corrugate

FACTORS is generally constructed in one of 1) Unbleached Kraft Paperboard INFLUENCING SMALL two ways. In single-face 2) Bleached Kraft Paperboard corrugated board, there is a paper 3) Recycled Paperboard FLUTE CORRUGATE liner on only one side of the CHARACTERISTICS 4) Small flute corrugate fluting. In single-wall corrugated

board, the fluting is sandwiched We discuss the characteristics and The primary factors that between layers of paper liner. uses of each below. determine the characteristics of Which type of small flute board is small flute corrugated board are used depends on the printing Unbleached Kraft Paperboard— the profile, or height, of the flute method used by a folding carton often referred to as Solid and whether it is single-face or manufacturer. Unbleached Sulfate—is the most single-wall board commonly used substrate for

Single-face folding cartons. It is The flute profile Flute profile. produced from at least 80% of a corrugated board is virgin-unbleached wood pulp designated by letter. A, B, C Single-wall and is coated with a thin layer flutes are found in standard of kaolin clay and titanium corrugated board, which is In the litho-laminating printing dioxide to improve color, widely used in brown shipping method, single-face corrugated smoothness and printing boxes. A, B, and C flutes are board is used as an input. In this receptivity. Unbleached Kraft can typically 2.0 to 4.8 millimeters in method, a folding carton also be treated with a moisture height. E, F, G, N, and O flute are manufacturer prints onto a thin barrier for use in liquid and food found in small flute corrugated paperboard (10 to 12 points), packaging. boards. The profile of these flutes which is then laminated onto the ranges from 0.3 to 1.8 millimeters. single-face small flute corrugate. The use of unbleached, usually

The application of the printed softwood pulp results in good The flute profile greatly paperboard creates a single-wall tear resistance and the greatest influences the strength, stiffness, corrugated board with printing stiffness and strength in relation creasing and folding qualities of a on one side. This board is to basis weight of the paperboard corrugated board. In general, converted into the end packaging substrates. Thus, Unbleached corrugated boards with smaller product. Kraft often allows for the use of a flute profiles have less vertical lower caliper paperboard relative compression strength, less In the direct offset method, a to other substrates. It also has stiffness and greater flexibility folding carton manufacturer cost advantages over bleached than boards with larger flute prints directly onto the virgin paperboard. profiles. The greater flexibility corrugated substrate. This and superior creasing and folding method requires a single-wall Unbleached Kraft is used in many qualities of small corrugate corrugated substrate as an input folding carton applications, (relative to standard corrugate) into the process.

© 2003 Independent Carton Group The ABC‘s of Folding Carton Substrates Page 3 especially when strength and Recycled paperboard is produced the corrugated medium increases durability are paramount. from recovered paper collected stiffness and strength but also Typical uses are consumer from paper manufacturing and adds cost to the converting electronics packaging, beverage converting plants and post process. carriers, dry food packaging, consumer sources. It represents hardware packaging, and the single largest market for Small flute corrugate is generally packaging for powdered recovered paper in the United used in high-end packaging in detergents and soaps. States. which strength and stiffness are essential. It can also be used to Bleached Kraft—often called Recycled paperboard is a multi- provide large windows in solid bleached sulfate (SBS)—is ply substrate with six to nine packaging while maintaining the highest quality and most plies. Due to the degradation of structural integrity. Typical uses expensive paperboard substrate. fibers during the recycling include small appliance It is produced from bleached process, virgin fibers are usually packaging, overnight shipping virgin wood pulp that is added to increase strength. boxes, beverage carriers, club produced with a chemical Nevertheless, recycled substrates store boxes, sporting goods pulping process. Most Bleached generally have lower stiffness per packaging, and toy packaging. Kraft paperboard grades are clay- unit weight and inferior printing coated to enhance the smoothness surfaces to virgin substrates. and receptivity of the printing However, recycled paperboards surface. Like Unbleached Kraft, have cost advantages, which ICG suppliers Potlatch Corporation SBS can be treated with a make them an economical and MeadWestvaco contributed to moisture barrier for use in liquid alternative for many folding this article. ICG member All and food packaging. carton applications. Packaging Company also contributed and provided Bleached cellulose pulp has high There are four main grades of illustrations. For more information whiteness, brightness and light recycled paperboard: about substrates and their stability. Thus, Bleached Kraft is appropriate uses, contact the white throughout the sheet and is ‹ Clay Coated News Back contributors or any ICG member. ideal for packaging requiring (CCNB) is brown or gray, high impact graphics. The depending on the type of softness and flexibility of fiber used, and clay coated on bleached virgin pulp provides one side superior creasing, embossing, and ‹ Clay Coated Light Back cutting properties with low dust (CCLB) is light gray with a generation, allowing for a wide clay coating on one side scope of structural designs. ‹ Clay Coated Kraft Back However, the bleaching process (CCKB) is brown and clay also adds cost and reduces coated on one side stiffness. Bleached Kraft ‹ Bending Chip (BC) is brown paperboard has the highest purity and not coated. and provides food products with the best odor taste and taint Recycled substrates are used in protection. many folding cartons applications, including hardware SBS is typically used in high-end packaging, auto parts packaging, packaging, where the impact and overnight envelopes, and quality of the printed image are partitions. essential. It is also used in food packaging to ensure taste Small Flute Corrugate is a multi- protection. Common uses are ply substrate in which small flute health and beauty packaging, corrugated medium is pharmaceutical packaging, and sandwiched between thin layers frozen foods. of paperboard. The addition of