-SQA-SCOTTISH QUALIFICATIONS AUTHORITY. Hanover House 24 Douglas Street GLASGOW G2 7NG NATIONAL CERTIFICATE MODULE DESCRIPTOR

Transcription

1 -SQA-SCOTTISH QUALIFICATIONS AUTHORITY Hanover House 24 Douglas Street GLASGOW G2 7NG NATIONAL CERTIFICATE MODULE DESCRIPTOR -Module Number Session Superclass- -Title- WL PAPERMAKING: FIBRES, PAPER AND PROPERTIES -DESCRIPTION- Type and Purpose A general module which enables the student to acquire an understanding of the range of paper and paperboard types produced and their required properties, and to relate these properties to the available raw materials and the manner in which they have been produced. Preferred Entry Level Standard Grade 3 Science. Learning Outcomes The student should: 1. know the main types and uses of paper and paperboard produced in the UK and their relative importance to the UK industry; 2. know the general chemical and physical makeup of papermaking fibres from differing fibre sources; 3. know the methods in common use for producing papermaking pulp from raw materials; 4. know and apply the principles and apparatus used to evaluate the relevant physical properties of pulp and paper; 5. comply with regulations and procedures and use safe working practices specified for equipment and work areas.

2 Content/ Context Corresponding to the Learning Outcomes: 1. UK Paper and Board Types and Qualities Introduction to pulping paper and boardmaking. The main qualities of paper and board. Different uses. The make up of the UK paper and board industry. The main products in the UK. Relative tonnages of each. The position of the UK industry in the world context. Major pulp producing areas of the world. Major paper producing areas of the world. Annual tonnage of the UK industry. Common raw materials. Constituents of plant tissue. Sources of fibrous raw materials. Importance of recycled fibre. General pulp and paper manufacturing process. Outline of wood pulping processes, stock preparation and main additives. Outline of the basic features of a fourdrinier machine. Outline of the basic features of the board vat machine. Outline of the function of drying cylinders, MG and Yankee cylinders. Outline of the basic features of a finishing end as re-reeler supercalender, cutters and guillotines. 2. Cellulose and Structure of Fibres Main sources of natural fibres. Description of the structure of cellulose and its different forms. The organic formula for true cellulose. The significance of lignin, natural resins and organic acids found in fibres and their associated problems. Main constituents of wood and their proportions. Morphological characteristics of the main fibres. Colour reactions of fibres with a common stain e.g. Herzberg. Outline of standard method of slide preparation. Production of transverse section drawing and explanation of the structure of softwood tracheid. The microscopic structure of: (d) (e) (f) softwood; hardwood; cotton; linen; esparto; straw. -2 -

3 The significance of fibre treatment in papermaking. Classification of fibre, e.g. length etc. Theory of hydrogen bonding. External and internal fibrillation. Beating and associated terms. Function of the Schopper Riegler wetness or Canadian freeness tester and their uses and limitations. Fibre selection, stock preparation and paper properties. Beating curves for strength properties: (d) burst; tensile; tear; Fold; Principles of paper testing equipment: (d) (e) (f) burst tester; tensile tester; tear tester; fold tester; air-porosity tester; opacity measurement. Relationship of properties to stock preparation. Definition of bulk and density and their relation to paper properties. Fibre dimensions and structure to papermaking properties. Effects of recycling on the papermaking properties. 3. Pulping Treatment of fibrous raw materials for papermaking. The processes for the production of mechanical or ground wood, refiner mechanical and thermo mechanical pulps. The production of chemical pulp by the acid sulphite, neutral sulphite, bisulphite, soda and sulphate processes. 3. Chlorinating and Bleaching Definition of bleaching. Use of hypochlorite in bleaching. Precautions against hypochlorite degradation. Use of chlorine dioxide. Definition of 'antichlor' and examples. Chlorine number and permanganate number. Definition of chlorination stage as a continuation of digestion to remove lignin. Description of chlorination stage. Precautions for safety and avoidance of degradation. Description of caustic extraction stage. Functions of the stage. Different raw materials and their treatments. -3 -

4 Stages and modifications for sulphate pulp and for the multistage bleaching of sulphate pulp. Block diagrams to represent the stages on the multistage bleaching of pulp following continuous digestion. Oxygen bleaching. Essential stages, advantages. Bleaching in relation to mechanical wood pulp. Use of peroxide and reducing agents. Advantages of the addition of the peroxide stage. 4. Pulp Evaluation Reasons for manufacturer and customer evaluations. Requirements of standard testing methods. BPBIF standard pulp evaluation process. Purpose of pulp evaluations. Need for standardised design and dimensions. Main steps in sheetmaking from preparation to drying. Main variables in method. Limitations and precautions necessary for good reproducibility and accuracy. Labelled diagrams of standard sheetmaking apparatus. Common tests carried out on sheets. Visual inspection. Common tests for pulp evaluation with SI units for each. Typical graphs of strength values and beating time against SR. Reporting of test results. Principles of wetness and freeness tests. Definition of wetness and freeness. Description of Schopper Riegler wetness test. Canadian freeness test. Main aspects of drainage time test using standard sheetmaking apparatus. Correlation between the three tests. Use of wetness and freeness values in mill and laboratory. Limitations of the use of these values. Precautions in using the tests to maximise reproducibility and accuracy. Dirt count on pulp. Methods of determining shive content and dirt counting using TAPPI dirt estimation chart. 4. Paper and Board Testing Principles and reasons for testing. Use of standard conditions. Hysteresis curve of moisture content plotted against relative humidity. Outline of sampling for testing from store (BS 3430:1968) Description of sampling from reels for routine quality control testing, British Standard conditions for test laboratories. Requirements of standard methods. -4 -

5 British Standards for quantitative methods. Outline and description of grammage tests and thickness tests. Significance of apparent density. British Standards for strength and durability. Reasons for tests of strength and durability. Tensile strength and stretch. Dynamic tensile test. Burst strength test. Internal tearing strength test. Folding endurance test. Stiffness test (non BS). Wet strength test. Significance of all tests. Constructional details of tensile tester, burst tester, tear tester, fold tester, stiffness tester. Principles of tests of stability. Degree of curl of board test. Wet expansion test (Fenchel value). Press room tests with Pira PET, Pira stack thermometer, sword hygroscope. Significance of all tests. Methods used by mill and printer for improving paper stability. Basic tests of surface properties. Abrasion resistance. Dennison wax and IGT tests for pick resistance. Significance of pick resistance. Methods of fluffing test. Significance of fluffing. Bendsten smoothness and compressibility test. Other methods. Significance of smoothing. Constructional details of IGT tester, Pira fluff tester, Bendsten tester. Penetration by fluids test. Sizing degree test by Cobb. Tests by wet and dry indicators. Tests of sizing degree by using ink and contact angle. Bendsten porosity test. Surface oil resistance test. K and N ink absorbance test. Significance of tests. Test apparatus. Constructional details of Cobb apparatus, Bendsten porosity head, and surface oil resistance test apparatus. Test of optical properties. Definition of 'show through' and 'strike through' Tests for printing opacity, contrast ratio and significance of tests. Definition of blue reflectance (brightness). Formations test and significance of test. -5 -

6 Constructional details of 'EEL' opacimeter. User tests. Purpose of user tests. Correlation of user tests and practical examples. Determination of ash and moisture content. Ageing properties tests. Significance of tests. Assessment of paper quality by observation. Principles of tests of strength for packaging materials. Tests for ring crush of board and flat crush of corrugated medium and plybond in multiply boards. Constructional details of apparatus for testing ring crush, flat crush and plybond. 5. Safety, safe practices, care and use of equipment. Suggested Learning and Teaching Approaches This module encompasses the knowledge of the basic principles and tests used in paper and boardmaking and a didactic approach should be supplemented with practical activities using test equipment and the handling and recognition of paper samples. Industrial visits could be useful and appropriate for this module. Assessment Procedures All Learning Outcomes must be validly assessed. The students must be informed of the tasks which contribute to summative assessment. Any unsatisfactory aspects of performance should, if possible, be discussed with the student as and when they arise. Acceptable performance in the module will be satisfactory achievement of the performance criteria specified for each Learning Outcome. The following abbreviations are used below: LO IA Learning Outcome. Instrument of Assessment. Performance Criteria. LO1 IA Written short answer test. The student correctly: lists the main types of paper and paperboard produced in the UK; describes their uses; -6 -

7 describes their relative importance to the UK industry. LO2 IA Written short answer test. The student correctly describes the chemical and physical make-up of papermaking fibres. LO3 IA Written exercise. The student correctly describes the methods in common use for producing papermaking pulp from raw materials. LO4 IA Practical exercises and written reports. (I) (ii) (iii) (iv) The student: performs six tests/calculations in which: apparatus is correctly selected; apparatus is correctly used; accurate readings are taken; reports are accurate and valid; correctly describes other tests. LO5 IA Observation checklist based on practical work in Learning Outcomes (in which the following elements must be included). The student: wears all necessary safety clothing and equipment; behaves in a manner appropriate to the working environment; uses tools and equipment safely. -7 -