Paperboard

Key takeaways

Paperboard belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Paperboard to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Paperboard from memory before moving on to harder problems.

Reference excerpt

Paperboard is a thick paper-based material. According to ISO standards, paperboard is a paper with a grammage above 250 g/m2, but there are exceptions. Paperboard can be single- or multi-ply. The related term box board dates at least to the 1790s. Terminology and classifications of paperboard are not always uniform. To produce paperboard, fibrous material is turned into pulp and bleached to create one or more layers of board, which can be optionally coated for a better surface and/or improved appearance. Pulp board is produced on pulping machines that can handle higher grammage than paper and several plies.

Description Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 points) than paper and has certain superior attributes such as foldability and rigidity. According to ISO standards, paperboard is a paper with a grammage above 250 g/m2, but there are exceptions. Paperboard can be single- or multi-ply. Paperboard can be easily cut and formed, is lightweight, and because it is strong, is used in packaging. Another end-use is high quality graphic printing, such as book and magazine covers, business cards, brochures, and postcards. Paperboard is also used in fine arts for creating sculptures. Sometimes it is referred to as cardboard, which is a generic, lay term used to refer to any heavy paper pulp–based board, however this usage is deprecated in the paper, printing, and packaging industries as it does not adequately describe each product type.

History Box board, with the meaning of "[w]ooden board or cardboard suitable for making boxes" dates at least to the 1790s. In 1817, the first paperboard carton was produced in England. Folding cartons first emerged around the 1860s. To save space, manufacturers shipped them flat, ready for setting up by customers when required. The mechanical die cutting and creasing of blanks was developed in 1879 using a die. In 1911, the first kraft sulphate mill was built in Florida. In 1915, the gable top milk carton was patented and in 1935 the first dairy plant was observed using them. Ovenable paperboard was introduced in 1974.

Terminology and classification

Terminology and classifications of paperboard are not always uniform. Differences occur depending on specific industry, locale, and personal choice. In general, the following are often used:

Boxboard or cartonboard: paperboard for folding cartons and rigid set-up boxes Folding boxboard (FBB): a bending grade capable of being scored and bending without fracture Chipboard: a recycled, low quality board White lined chipboard (WLC): a white, often clay-coated chipboard Kraft board: a strong virgin fiber board often used for beverage carriers. Often clay-coated for printing Laminated board: a lamination of paperboards and other materials, for example liquid packaging board Solid bleached board (SBB) or solid bleached sulphate (SBS): clean white board used for foods etc. Sulphate refers to the kraft process Solid unbleached board (SUB): board made from unbleached chemical pulp Containerboard: a type of paperboard manufactured for the production of corrugated fiberboard Corrugated medium: the inner fluted portion of corrugated fiberboard Linerboard: a strong stiff board for one or both sides of corrugated boxes. It is the flat covering over the corrugating medium. Other Binder's board: a paperboard used in bookbinding for making hard covers.

Production

To produce paperboard, fibrous material is turned into pulp and bleached to create one or more layers of board, which can be optionally coated for a better surface and/or improved appearance. Pulp board is produced on pulping machines that can handle higher grammage and several plies.

Raw materials The above-mentioned fibrous material can either come from fresh (virgin) sources (e.g. wood) or from recycled waste paper. Around 90% of virgin paper is made from wood pulp. Today paperboard packaging in general, and especially products from certified sustainable sources, are receiving new attention, as manufacturers dealing with environmental, health, and regulatory issues look to renewable resources to meet increasing demand. It is now mandatory in many countries for paper-based packaging to be manufactured wholly or partially from recycled material. Raw materials include:

Hardwood C. 0.05 inches (1.3 mm) in length e.g. Birch which has short fibres. It is generally more difficult to work with; however, it does provide higher tensile strength, but lower tear and other strength properties. Although its fibres are not as long and strong as those in softwood, they make for a stiffer product defined by some stiffness tests. Hardwood fibres fill the sheet better and therefore make a smoother paper that is more opaque and better for printing. Hardwood makes an excellent corrugating medium. Softwood C. 0.13 inches (3.3 mm) in length e.g. Pine and spruce which have typically long fibres and make superior paperboard in services where strength is important. Softwood makes excellent linerboard. Recycled Used paper is collected and sorted and usually mixed with virgin fibres in order to make new material. This is necessary as the recycled fibre often loses strength when reused; the added virgin fibres enhance strength. Mixed waste paper is not usually deinked (skipping the deinking stage) for paperboard manufacture and hence the pulp may contain traces of inks, adhesives, and other residues which together give it a grey colour. Products made of recycled board usually have a less predictable composition and poorer functional properties than virgin fibre-based boards. Health risks have been associated with using recycled material in direct food contact. Swiss studies have shown that recycled material can contain significant portions of mineral oil, which may migrate into packed foods. Mineral oil levels of up to 19.4 mg/kg were found in rice packed in recycled board. Others It is also possible to use the fibres of Sugarcane Bagasse, Straw, Hemp, Cotton, Flax, Kenaf, Abaca and other plant products.

Pulping

Two principal methods for extracting fibres from their sources are:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Paperboard

Start with the simplest possible case. Write down what Paperboard claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Paperboard before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Paperboard ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Paperboard

In research: Paperboard appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Paperboard in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Paperboard is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coated paper, English inventions, Packaging materials, so understanding it makes those chapters shorter.
In everyday life: Look for Paperboard outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Paperboard in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Paperboard means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Paperboard out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Paperboard in simple terms?

Paperboard is a thick paper-based material. According to ISO standards, paperboard is a paper with a grammage above 250 g/m2, but there are exceptions.

Why does Paperboard matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Paperboard?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Paperboard.