02 Paper, card and board

Transcription

1 02 Paper, card and board How are paper and board made? 18 Properties and uses of paper and card 20 Cartonboard 22 Tip for note taking: USE BIG SECTION TITLES and P.29 Sub Titles And bullet points for key info

2 How are paper and board made? Objectives Learn how papers and boards are made. Understand why there are so many different types. Know the units that paper and card are measured in. Why are there so many different types of paper? We all use many types of paper and board in graphics. They are made from the vegetable fibres found in wood, which are carefully extracted through the process of crushing wood to make a 95 per cent water- based pulp. This looks a bit like milk. It is then refined by being passed through a series of dryers and rollers to achieve the basic quality that paper-makers need for board or paper.

3 Factors for Selecting Perhaps without realising it, you have already used a huge range of different boards and papers. Just think about your daily routine and the boards used for cereal packets, egg boxes, juice cartons, newspapers, school books, and so on. Each has been carefully created to have certain qualities. The main factors that are taken into account when choosing a paper or board are: 1. Cost 2. Finish 3. Strength 4. Brightness (whiteness) 5. Thickness For each of the items, identify the two factors that are most important

4 How do we get these different properties? A really shiny paper, like the expensive photo paper you can print your pictures on, gives a very different glossy finish than the much cheaper and thinner newsprint paper used for newspapers, which is a low quality, cheap, thin, matt and absorbent paper.

5 3 ways of achieving the different properties of paper and card: 1. A coating to the surface, such as china clay or chalk, which is sprayed on to the surface to give a smoother finish 2. A sizing agent which improves the ability of the paper or card to accept ink by sealing the absorbency of the paper s surface. The coating and sizing applied to the surface directly affect the brightness (whiteness) of the surface 3. Laminating (sticking together) layers of thinner card to achieve a board. Depending on how many layers of card are stuck together, and the qualities of each card, a whole range of different boards can be made. Examiner s tip Make sure you are able to say what properties a particular paper or card has and why you think it would be suitable for a particular use. Summary Paper is made from the vegetable fibres found in wood. Paper comes in a huge variety of weights, colours and textures. Paper-makers change the properties using three methods: coatings, sizing agents, laminating.

6 Weight and thickness Paper is sold by weight in grams per square metre (gsm) up to 220 gsm Board is sold and measured for thickness in units called microns, represented by the symbol μm. There are 1000 microns in 1 mm and a typical birthday card is around 300 microns thick, compared with the paper this book is printed on which is about 90 gsm in weight. Key Terms Grams per square metre (gsm): paper thickness is measured in gsm, which is the weight in grams of a whole square metre of paper. Microns (μm): card thickness is measured in microns. A micron is 1/1000th of a millimetre.

7 Recycling Virgin paper makes up 90 per cent of all paper, and the remaining 10 per cent of paper has some recycled content. Compared with recycled paper, virgin paper tends to be stronger and brighter white. Virgin paper is used generally for food containers because it reduces the contamination risk to the food products. It is also possible to make paper from all sorts of materials other than wood pulp, such as corn, straw, cotton and hemp, and each of these materials gives the paper different properties. It is important that we try to recycle as much as possible in order to try to save our planet from additional global warming. The Energy Information Administration claims that a 40 per cent reduction in energy is achieved when paper is totally recycled, compared with the energy used in making virgin paper. About 30 per cent of solid waste dumped in landfill is paper-based and the rotting down of this waste produces methane, which is a bad greenhouse gas. Deforestation is also a massive environmental issue, and some of the wood is used by the paper industry. Deforestation can cause global warming because trees absorb CO2, which is the main greenhouse gas.

8 Advantages and disadvantages of recycling paper Advantages Kinder to the environment 34 per cent of trees cut down are for paper manufacturing Energy saving due to less raw material being processed PR: Companies like to be seen to be greener these days and this is an easily understood message for the consumer Disadvantages Harmful chemicals to the environment, such as bleach are sometimes used to achieve a white paper Not as strong as virgin paper More expensive to make than virgin paper

9 Corriflute and Duplex. Two other boards that are widely used in graphics are Corriflute and Duplex. Corriflute or Correx is a fluted polypropylene (plastic) board and is a light but strong weather-resistant material that is excellent for use as exterior signage, unlike paper-based boards. It can be printed on to using flexography, or vinyl stickers can be used. A good example of its use is the For Sale sign of estate agents outside houses. Duplex while cartonboards are mainly used for packaging, larger and more rigid multilayered display boards like Duplex have a greater variety of uses. They are made using a foam base board to which various finishes are applied. A good example are the boards often used for advertising purposes in shops and cinemas which can be coated with a smart foil material with an image that reacts to light and changes (hologrammatic).

10 Table of paper and card

11 Cartonboard Nearly everything we buy is packaged in some form. If you look closely at the packaging on any two different products, you will probably find that the card is slightly different for each one and that the items are over-packaged. If a card is used for the external package, then it is likely to be a type of cartonboard. Cartonboard is mechanically strong, so it is good at protecting products. It can also easily be cut, creased, folded and glued, giving you, the designer, scope to produce functional and creative packaging. The surface is usually white and smooth and can be printed on using all the main printing processes. Cartonboard can be embossed and hot-foil stamped (see Chapter 20 for more details). In Europe about 7 million tonnes of cartonboard are produced each year and the majority of this is then converted into cartons for packaging products like food, drink and cosmetics. Some is also used for graphical purposes, such as book covers, postcards, calendars and brochures.

12 How is cartonboard made? Cartonboard is a multilayered or laminated material with three or more layers (plies). It usually has a white coating on one or both surfaces to make it easier to print on. Cartonboard types vary according to the pulp composition and the thickness in microns. Cartonboard can be combined with other materials such as plastic to make it waterproof. Most folding cartons are in the range of μm (microns) for thickness. There are four basic types of cartonboard manufactured: 1. solid bleached board 2. solid unbleached board 3. folding boxboard 4. white lined chipboard They can be treated with various chemicals to improve a variety of properties such as moisture and grease barriers. Additionally, they can be coated to produce cartonboard that can be used in ovens and microwaves and other specialist packaging. Cartonboard can be treated or laminated. Although these additions give the card unique uses, they all make the card far more difficult to recycle. Examples of treatments include:

13 Coatings Aluminium foil for insulation, or as a bacterial barrier for food products, for example Capri-Sun drinks containers Plastic for waterproofing, for example Innocent smoothie drinks cartons Greaseproof paper, for example baking cups for cup cakes Wax coating for waterproofing, for example a takeaway coffee cup Coating cartonboard

14 Summary There are four main types of cartonboard. There are many ways to modify and add to the properties of cartonboard. Cartonboard is used for a very wide range of packaging. Examiners tip Make sure you understand that cartonboard varies tremendously, depending on the lamination and coating. You need to be able to say why a particular cartonboard is used. Apply your Knowledge Questions & slides