1、BRITISH STANDARD BS ISO 11556:2005 Paper and board Determination of curl using a single vertically suspended test piece ICS 85.060 BS ISO 11556:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2005 BSI 31 October 2005 ISBN 0 58
2、0 46443 1 National foreword This British Standard reproduces verbatim ISO 11556:2005 and implements it as the UK national standard. It supersedes BS ISO 11556:1998 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PAI/11, Method of test for paper, board
3、 and pulp, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and prom
4、ulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “Inter
5、national Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a Br
6、itish Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 12, an inside back cover and a back cover. The BSI copyright notice displayed in this d
7、ocument indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 11556:2005(E)INTERNATIONAL STANDARD ISO 11556 Second edition 2005-06-15 Paper and board Determination of curl using a single vertically suspended test piece Papier et
8、carton Dtermination du tuilage au moyen dune prouvette unique suspendue verticalement BS ISO 11556:2005ii BS ISO 11556:2005 iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 2 5 Apparatus 3 6 Sampling 3 7 Preparation of test p
9、ieces 3 8 Procedure 3 8.1 General information 3 8.2 Method . 4 8.2.1 Exposing the test pieces to the test environment. 4 8.2.2 Measurement of chord length and chord-to-arc distance 4 8.2.3 Identification of the side towards which the paper or board curls 4 8.2.4 Measurement of the angle of axis of c
10、url . 4 9 Calculations. 5 9.1 Magnitude of curl 5 9.2 Angle of curl axis 5 9.3 Variation in side towards which paper or board curls 5 10 Repeatability and reproducibility 5 10.1 Repeatability . 5 10.2 Reproducibility . 6 11 Test report . 6 Annex A (informative) Illustrations of magnitude and types o
11、f curl . 7 Annex B (normative) Method of test piece support during curl measurement (illustrated for circular test pieces) 9 Annex C (normative) Modified engineers vernier calliper for determining chord length (C) and chord-to-arc distance (h) 10 Annex D (informative) Examples of alternative curl ca
12、lculations . 11 Bibliography . 12 BS ISO 11556:2005 iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees.
13、 Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Interna
14、tional Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Stan
15、dards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subje
16、ct of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 11556 was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee SC 2, Test methods and quality specifications for paper and board. This second edition cancels and replac
17、es the first edition (ISO 11556:1998), of which it constitutes a minor revision, and Technical Corrigendum 1, published 2003-04-01, which has been incorporated into this edition. v Introduction The presence of curl in paper and board may be detrimental to its processing, and therefore there is a nee
18、d for its measurement. Curl can be inherent in the paper when manufactured, or can be developed in the sheet during its use. This International Standard describes the procedure to be used for determination of curl in a pack of sheets. BS ISO 11556:2005blank1 Paper and board Determination of curl usi
19、ng a single vertically suspended test piece 1 Scope This International Standard gives a procedure for determining the curl of paper and board using a vertically suspended test piece, and defines the terms used in curl measurement. This International Standard may be used to measure any curl when the
20、curl formed approximates the arc of a circle; the curl is stable enough to remain constant during the time required to cut the test pieces and make the measurement. This primarily includes curl in paper or board as received or after exposure to a constant climatic condition, such as a test room or p
21、rint shop. NOTE 1 The choice of conditioning climate and conditioning time depends on the purpose of the testing. NOTE 2 For papers coated on one side or gummed-label papers, a period of at least 24 h, after production, should be allowed to permit the paper to stabilize before any curl tests are don
22、e. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 186, Paper and boar
23、d Sampling to determine average quality ISO 187, Paper, board and pulps Standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 c
24、url deviation from a flat surface NOTE Its measurement has three major components: its magnitude; the angle of the curl axis in relation to the paper or boards machine direction; the side towards which the sheet curls. BS ISO 11556:20052 3.1.1 magnitude measured deviation of a test piece from a flat
25、 surface NOTE 1 Magnitude is expressed as the reciprocal of the curvature of the curled test piece with units of m 1 . NOTE 2 The radius of curvature for the curled test piece is the distance from the arc to the centre of the circle of which the arc is a part. The reciprocal radius (1/R) has a value
26、 of zero for a flat sheet. NOTE 3 Curl characteristics of paper and board are time dependent and the magnitude of any curl displayed may be transient. 3.1.2 angle of curl axis (see Annex A) angle between the axis of the curl and the machine direction of the paper or board, viewed from the concave si
27、de NOTE 1 For a curl that has its axis perpendicular to the machine direction, = 90; for a curl that has its axis parallel to the machine direction, = 0. When the axis of the curl is neither perpendicular nor parallel to the machine direction, it is sometimes referred to as “diagonal curl” (occasion
28、ally as “asymmetric curl”, “twist curl” or “wrap curl”). For diagonal curl, if the machine direction is positioned in a clockwise direction from the axis of the curl, this is deemed as a positive (+) rotation, but if it is in a counter-clockwise direction, then this is deemed as a negative () rotati
29、on. The angle of curl axis can be positive or negative between 0 and 90. NOTE 2 Note that the rotational direction in a diagonal curl is reported as being clockwise (+) or counter-clockwise () from the axis of the curl to the machine direction, and not from the machine direction to the axis of the c
30、url. 3.1.3 concave side side towards which the paper or board curls NOTE See Annex A. 3.2 induced curl change in curl (3.1), caused by some treatment to one or both sides of the paper or board NOTE A curl is often induced in a test piece to indicate the processability of a paper or board in an end-u
31、se situation. 3.3 double curl flipper curl a form of curl which tends to alternate between the two sides with light manipulation of the sheet NOTE This tendency is a phenomenon which may be described as two curl patterns that are finely balanced within the same sheet of paper or board. 4 Principle T
32、est pieces of paper or board are exposed to the desired test environment. The curl is measured with the test pieces suspended such that the axis of the curl is vertical. BS ISO 11556:20053 5 Apparatus 5.1 A device to cleanly cut out test pieces to a set diameter or size. For circles, the preferred d
33、iameter is 112,8 mm 0,1 mm (100 cm 2 ). For square test pieces, the preferred size is (100 mm 100 mm) 0,1 mm. NOTE Circular and square laboratory cutters to produce 100 cm 2test pieces are commercially available for sheet grammage determinations. 5.2 A device for supporting the test piece during mea
34、surement, see Annex B. 5.3 A device for measuring the chord and chord-to-arc distance to within 0,5 mm (for example, a modified engineers vernier calliper, see Annex C). 5.4 A device for measuring the angle of curl accurately to within 1. NOTE Automated methods of determining the curl magnitude and
35、the angle of the curl axis may be used provided they are at least as accurate as the method described in this International Standard. 6 Sampling If a consignment of paper or board is being evaluated for curl, select the sample in accordance with ISO 186. Protect the sample from moisture change if th
36、e curl is to be measured as received. If the test is being made on another type of sample, report the source of the sample and, if possible, the sampling procedure used. Make sure that the test pieces are representative of the paper or board sample. After sampling, care should be taken to ensure tha
37、t all samples are kept in the same relative orientation. 7 Preparation of test pieces Select undamaged specimens free from folds or wrinkles, and preferably free from watermarks. In the areas from which the test pieces will be cut, lightly mark the machine direction, if possible on the same side of
38、each test piece. When marking the test piece, take care not to make indentations which may affect the curl. This side of the test piece will then be referred to as the “marked side”. Cut ten test pieces, one at a time, with the machine direction marks lying along the centre-line of the test piece. C
39、ircular test pieces are preferred. However, square test pieces conforming to the dimensions given in 5.1 are also acceptable. It is very important that one side is marked. If possible, the marked side should be identified by a distinguishing feature, such as wire marking, coating, watermark, glazing
40、, etc. If the side cannot be identified, then the side facing the wrapper of a sealed ream, or the upper face of the top sheet on an open skid of paper, should be the marked side. 8 Procedure 8.1 General information The procedure specified in 8.2 assumes that an instrument such as a modified enginee
41、rs vernier calliper (see Annex C) is employed. This instrument can be used to measure the chord length and chord-to-arc distance, from which parameters the curl magnitude (as reciprocal radius of curvature) is calculated. In principle the instrument can be used, with the formula in 9.1, to determine
42、 the curl of any sample. There will, however, be practical limitations imposed by the geometry of the measuring apparatus. Examples of curl shapes which may be obtained are shown in Annex A, which also shows the chord length (C) and chord-to-arc distance (h). NOTE The chord-to-arc distance is the ma
43、ximum distance from the chord to the arc, measured upon a line perpendicular to the chord. BS ISO 11556:20054 8.2 Method 8.2.1 Exposing the test pieces to the test environment Suspend the test piece in the test environment by means of a small hook or clip placed near the edge of the test piece along
44、 the line marking the machine direction. Within the required time limits, observe the approximate curl axis and concave side. Keeping the test piece in the same environment, carefully remove the test piece and, using a small-headed pin, fix it at its centre against the vertical support (see 5.2) so
45、that the concave side is facing the operator. Rotate the test piece so that the axis of curl is vertical. At the top of the test piece, mark the centre-line of the curl axis and then, at this point, fix the top of the test piece to the support by another pin. If determining the curl of paper or boar
46、d without conditioning (i.e. as received), the exposure and measurement procedure should be carried out as rapidly as possible to minimize any significant change in curl. NOTE 1 Care is needed when attaching the test piece to any suspending or supporting devices so as not to bend the test piece in s
47、uch a way that the curl would be affected. NOTE 2 Test pieces may be exposed and measured horizontally by placing the test pieces on a flat surface with the concave side up, if it can be shown within experimental error that gravity does not have a significant influence on the test result. (Board tes
48、t pieces are generally too stiff to be significantly influenced by gravity.) In cases where square test pieces exhibit a significant diagonal curl, difficulties in measurement are such that the results should be treated with caution. 8.2.2 Measurement of chord length and chord-to-arc distance Use ci
49、rcular or square test pieces. Protect test pieces from drafts during the measurements. Using the modified vernier calliper, measure the length of the chord (C) across the centre of the test piece to the nearest 0,5 mm and measure the chord-to-arc distance (h) to the nearest 0,5 mm. Repeat the procedure with the remaining nine test pieces. NOTE 1 In order to obtain accurate measurements when using the modified vernier calliper,
