2 3 1 a Paper and Board

Transcription

1 2 3 1 a Paper and Board Preparation From the tables on pp 32 33, scavenge as many examples as you can and bring them to the lesson! Read pages Resources Student preparation Examples of softwoods as well as types of paper and card Key Points: Wood Pulp Wood pulp Individual fibres separated by removal of lignin Softwood fibres Longer, stronger Hardwood fibres Shorter, smoother, opaque The table below compares the 3 types of pulp Mechanical pulp Chemical pulp Waste pulp Low investment cost Long, strong fibres Pulp ground down to 1-2 mm size Hardwood and softwood is debarked pulped Coniferous wood logs saturated with water and debarked Pounded into fragments and screened Recycled paper and card is Has to be mixed with virgin fibres to improve quality MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 1 of 11

2 Mechanical pulp Chemical pulp Waste pulp Bleached with peroxide or sodium hydroxide Pulp treated with acid or alkaline Lignin is completely dissolved and separated from the fibre Bonding agents and pigments are blended to produce various grades A sizing agent has to be added to improve water resistance and prevent ink from feathering on the surface Considerable processing and additives 90% yield (high) Low yield Fewer impurities Fewer impurities Greater impurities Low grade paper and packaging News print Packaging board High quality Chlorine free disposable products Waste lignin burnt to supply power to national grid or local steam Low grade paper News print Tissue Packaging boards MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 2 of 11

3 Mechanical pulp Chemical pulp Waste pulp Low strength Can yellow under bright lights due to high lignin content Not produced in the UK; it has to be imported Does not save energy MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 3 of 11

4 Key Points: Paper Manufacture Taken from During the drying process, sizing agents such as starch, resin and alum can be added Calendars (highly polished rollers) give a smooth, gloss finish See Start/Programs/Subject/Technology/(Focus) Plastics to see the principles of calendaring) The paper is placed onto a roll, cut to size or sent to the printing press Key Points: Paper Manufacture continued Wet end Press section Dryer section Calendar section MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 4 of 11

5 Key points: Paper, card, board and packaging Aesthetic Visual and tactile qualities Functional Required qualities to be fit for purpose Mechanical Reaction to forces Paper weight g/m 2 (not really density) Thicknesses and numbers of ply Know the descriptions, applications, properties and costs of paper, card and board Know the compositions, applications, properties and costs of commercial packaging Selection relates to Design requirements Printing process or surface decoration Economics and scale of production Carton boards High quality, high speed printing, cutting, creasing, gluing Total graphic coverage Excellent print quality Excellent structural protection in packaging nets Used extensively in the retail industry Continued MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 5 of 11

6 Key points: Paper, card, board and packaging Types of paper Types of card Types of packaging Wider study Table 2.1 Advantages and disadvantages of wood pulp Table 2.2 Common papers, card and board Table 2.3 Common carton boards Paper manufacture Why paper yellows Pulp and paper information centre Commercial D&T programme The Packagaging Industry Assignment Construct a display board of the different types of paper, card and packaging materials Homework As above Revision questions 1. Explain the production of ONE of the following pulps: Mechanical Pulp Chemical Pulp Recycled Pulp 2. Describe the Fourdrinier paper manufacturing process 3. Describe the production processes for a card breakfast cereal box 4. Describe corrugated board notes AND annotated sketches 5. Outline properties of corrugated board that make it a MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 6 of 11

7 commonly used packaging material 6. Describe corrugated board notes AND annotated sketches Specification and Learning Objectives Processes and advantages/disadvantages of producing wood pulp by the following methods: mechanical chemical waste pulp The process of manufacturing paper and card using the fourdrinier process Aesthetic, functional and mechanical properties, application and advantages/disadvantages of the following common paper, card and board for commercial and everyday use: drawing papers layout tracing copier cartridge commercial printing papers bond coated commercial card and board mounting board recycled Aesthetic, functional and mechanical properties, structural composition, application and advantages/disadvantages of the following carton boards in the the production of commercial packaging: folding boxboard corrugated board solid white board foil-lined board MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 7 of 11

8 Solutions to revision questions Next page MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 8 of 11

9 1. Explain the production of ONE of the following pulps: Mechanical Pulp Logs (coniferous wood) are saturated with water Logs are debarked Logs are ground (using a grindstone) down (to form a pulp) Pieces of 1-2mm produced (larger pieces are re-circulated) Pulp is bleached (peroxide or sodium hydroxide) High yield method Contains impurities Used in low-grade paper or packaging material Chemical Pulp Logs (hardwood & softwood) are debarked Logs are cut into 20mm chips (along the grain) Chips are pounded into fragments (and screened) Pulp is treated with acid or alkaline (bleach) This is done in tanks called digesters (involves heating) Lignin is dissolved away Fibres are filtered out then washed Lower fibre (pulp) yield than mechanical pulp Fibres are longer/stronger/fewer impurities (than mechanical pulp) Waste Pulp Recycled paper/card used Ground down into a pulp Used for lower grade paper Strength/durability/colour of lower quality (lower than MP/CP) Waste pulp can be mixed with virgin fibres (i.e. from MP/CP processes) this improves quality Processed with bonding agents/pigments/bleach A sizing agent may be added to improve water resistance/prevent ink from bleeding (feathering) 2. Describe the Fourdrinier paper manufacturing process Cellulose fibres/pulp, diluted with water (99% water approx) Cellulose fibres/pulp, fed onto woven mesh belt/wire frame The belt/frame is vibrated (to drain off water) The vibrating action causes the fibres to interweave The process is assisted via vacuum suction boxes (aids the removal of water) Rollers (some felt faced/some steel) press the fibres closer together (it forms a mat) Heat is used to speed-up the drying process 3. Describe the production processes for a card breakfast cereal box MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 9 of 11

10 Description of die-cutting process Process named (die-cutting process) Die cutting tools manufactured / set up Die cutting process cut and crease nets / developments Folding and gluing to form the box Explanation of why card is suitable for die-cutting Folding boxboard / white lined chipboard / virgin pulp most suitable materials because excellent materials for scoring, bending or creasing Can be recycled Card can be die-cut cheaply Card is cheap to buy in bulk Description of printing process Process named (flexography / lithography) Four colour rollers set up / CYMK Print onto card Explanation of why card is suitable for flexography / lithography Provides a good printing surface / appropriate surface to print on Varnishing / laminating / embossing may be mentioned can be used to enhance the format of the board Total graphic coverage Printing by flexography / lithography which is high speed Printing by flexography / lithography which is relatively cheaper than other printing methods for large runs Card is cheap to buy in bulk 4. Describe corrugated board notes AND annotated sketches N.B. 2 marks max. for ONLY notes OR annotated sketches (sketches only = 1 mark) Look for: 2 or more card layers Glued together Inner layer of lower grade pulp/card Inner layer folded in v form or fluted Top and bottom surfaces called liners Inner layer known as fluting / concertina effect Single wall board/double wall board/triple wall board Liners (kraftliners) are made from : kraft paper Kraft paper: smooth outer printing surface/ coarse inner gluing surface 5. Outline properties of corrugated board that make it a commonly used packaging material Any 2 of the following: Insulation / air pockets Excellent impact resistance / affords good protection Excellent strength for its weight / it is strong MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 10 of 11

11 Re-usable / recyclable Good stacking strength / rigid Resistant to tear and puncture Good life expectancy / durability / tough Good printing surface Inexpensive / cost effective Made from low grade pulp More durable than card Easy to cut and crease / fold into 3D package 6. Describe corrugated board notes AND annotated sketches 2 or more card layers Glued together Inner layer of lower grade pulp/card Inner layer folded in v form or fluted Top and bottom surfaces called liners Inner layer known as fluting / concertina effect Single wall board/double wall board/triple wall board Liners (kraftliners) are made from : kraft paper Kraft paper: smooth outer printing surface/ coarse inner gluing surface MIP/2 3 1 a Paper Board.doc Created on 06/11/ :55:00 Page 11 of 11