EN 21974:1994
(Main)Paper - Determination of tearing resistance (Elmendorf method) (ISO 1974:1990)
Paper - Determination of tearing resistance (Elmendorf method) (ISO 1974:1990)
It can also be used for light boards if the tearing resistance is within the range of the instrument, does not apply to corrugated fibreboard and is not suitable for determining the cross-direction tearing resistance of highly directional paper or board.
Papier - Durchreißversuch (Elmendorf Methode) (ISO 1974:1990)
Diese Internationale Norm beschreibt ein Verfahren für den Durchreissversuch von Papier. Sie kann auch für leichte Pappe angewandt werden, sofern die Durchreisssfestigkeit innerhalb des Messbereiches des Gerätes liegt. Diese Internationale Norm ist nicht anwendbar bei Wellpappe, aber sie kann bei den Komponenten dieser Pappe angewandt werden. Sie kann nicht zur Bestimmung der Durchreissfestigkeit in Querrichtung von hochrichtungsabhängigem Papier oder Pappe angewandt werden.
Papier - Détermination de la résistance au déchirement (Méthode Elmendorf) (ISO 1974:1990)
La présente Norme internationale prescrit une méthode pour la détermination de la résistance au déchirement du papier (résistance au déchirement amorcé). Elle peut aussi être utilisée pour le carton de faible grammage, si la résistance au déchirement se trouve dans le domaine d'utilisation de l'appareil. La présente Norme internationale n'est pas applicable aux cartons ondulés mais elle peut s'appliquer aux papiers pour ondulés. Elle ne convient pas pour déterminer la résistance au déchirement dans le sens travers des papiers (ou des cartons) à structure fortement orientée.
Papir - Določevanje raztržne odpornosti (Elmendorfova metoda) (ISO 1974:1990)
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Papier - Durchreißversuch (Elmendorf Methode) (ISO 1974:1990)Papier - Détermination de la résistance au déchirement (Méthode Elmendorf) (ISO 1974:1990)Paper - Determination of tearing resistance (Elmendorf method) (ISO 1974:1990)85.060Papir, karton in lepenkaPaper and boardICS:Ta slovenski standard je istoveten z:EN 21974:1994SIST EN 21974:2000en01-april-2000SIST EN 21974:2000SLOVENSKI
STANDARD
INTERNATIONAL STANDARD IS0 1974 Third edition 1990-02-O 1 ~- p-.-------- Paper - Determination of tearing resistance (Elmendorf method) Papier - D6termination de la rbsistance au dbchirement (MHhode Elmendorf) Reference number --- IS0 1974: 1990(E) SIST EN 21974:2000
IS0 1974:1990(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. 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, govern- mental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 1974 was prepared by Technical Committee ISO/TC 6, Paper, board and pulps. This third edition cancels and replaces the second edition (IS0 1974:1985), of which this constitutes a complete revision. In particular, this edition deals only with single tear testers, all references to double tear instruments having been deleted, and allows for the use of digital read-out variants. An alternative calibration procedure has been in- cluded. Annexes A and B provide details of the apparatus and calibration pro- cedures respectively. Annex C refers to units used with older apparatus. Annexes A and B Annex C is for info form an in rmation onl tegral part of this Y- International Standard. 0 IS0 1990 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii SIST EN 21974:2000
INTERNATIONAL STANDARD IS0 1974:1990(E) Paper - Determination of tearing resistance (Elmendorf met hod) 1 Scope This International Standard specifies a method for determining the tearing resistance of paper. It can also be used for light boards if the tearing resistance is within the range of the instrument. This International Standard does not apply to corru- gated fibreboard, but it may be applied to the com- ponents of such boards. It is not suitable for determining the cross-direction tearing resistance of highly directional paper (or board). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All stand- at-ds are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of ap- plying the most recent editions of the standards in- dicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 186:1985, Paper and board - Sampling to deter- mine average quality. IS0 187:1977, Paper and board - Conditioning of samples. IS0 536:1976, Paper and board - Determination of grammage. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 tearing resistance: The mean force required to continue the tearing started by an initial cut in a single sheet of paper (or board). If the initial cut is in the machine direction, the result is given as machine-direction tearing resistance; similarly, if the initial cut is in the cross direction, the result is given as cross-direction tearing resistance. The result is expressed in millinewtons (mN). 3.2 tear index: The tearing resistance of the paper (or board) divided by its grammage. The result is expressed in millinewton square metres per gram (mN.mVg). 4 Principle A test piece of superimposed sheets (normally four), with a specified precut slit, is torn through a fixed distance using a pendulum which applies the tearing force by moving in a plane perpendicular to the ini- tial plane of the test piece. The work done in tearing the test piece is measured by the loss in potential energy of the pendulum. The average tearing force (work done divided by the total distance torn) is indicated by a scale on the pendulum or a digital display. The tearing resistance of the paper is determined from the average tearing force and the number of sheets comprising the test piece. 5 Apparatus 5.1 Elmendorf-type tear tester, of suitable capacity complying with the requirements specified in annex A. NOTES 1 Some apparatus may be equipped with digital indi- cation of tearing resistance. Such apparatus normally re- places the friction pointer system with a transducer for sensing the angular movement of the pendulum. Transducer outputs are electrically processed to give a direct digital read-out of average tearing resistance. In other respects this type of apparatus conforms to the re- quirements of annex A. 1 SIST EN 21974:2000
IS0 1974:1990(E) 2 Under the conditions of this test, the total work done by the pendulum includes the work done in tearing the paper and also the work done in lifting and bending the test piece and overcoming friction between the torn edges of the test piece. With some instruments the total work done also includes overcoming frictional forces due to the test piece rubbing on the pendulum during the test. This is a major source of error on such apparatus, and appa- ratus on which this occurs are not considered suitable for testing in accordance with this International Standard. In- struments, modified by a suitable cut out to avoid this problem are available. 5.2 Augmenting masses or interchangeable pendu- lums to increase the tearing force capacity of the apparatus. 5.3 Means for prise a suitable preparing the die, guillotine test piece: or template may and com- knife. 6 Sampling Sample in accordance with IS0 186. 7 Conditioning Condition the sample in accordance with IS0 187. 8 Preparation of test pieces Prepare the test pieces in the same conditioning at- mosphere used to condition the samples. There shall be no folds, creases or other visible defects in the area from which the test piece is cut and the test piece shall not include any part of the sample that is less than 15 mm from the edge of the sheet or reel. If watermarks are present, this should be stated in the test report. Identify the two sides of the paper in a convenient way, for example, side one and side two and, with the same side up, from each specimen cut four rec- tangular sheets of the same size between 50 mm + 2 mm and 76 mm + 2 mm wide with edges parallel to the desired t&t direction and of such a length that after the initial cut has been made either as part of the test piece preparation or by means of the integral knife (see clause A.l), the untorn length is 43,0 mm & 0,5 mm long. Assem- ble the cut sheets into sets of four to make up the test pieces. Alternatively, arrange four specimens with their machine directions parallel and the same sides facing the same way and cut the test piece si- multaneously as described above. The untorn length shall be as specified above. The edges of the sheets comprising the test piece shall be free and not stuck together. NOTE 3 The exact test piece dimensions depend on the design of the apparatus clamps used. For certain appara- tus the appropriate dimensions are 50 mm wide x 63 mm long; for others 50 mm wide x 65 mm long or 63 mm wide x 76 mm long. A guillotine giving the appropriate test piece dimensions is normally supplied with the apparatus. Cut sufficient test pieces to give a minimum of IO valid tests in each required principal direction of the paper (i.e. a total of at least 40 sheets in each direction). 9 Procedure Carry out the tests in the same conditioning atmos- phere used to condition the samples. Set up and check the instrument as described in annex A. If necessary, calibrate the apparatus as described in annex B. Carry out a few tests by the procedure described below in order to select the appropriate pendulum or pendulum/augmenting mass combination. It is desirable to arrange for the mean readings to fall within the range 20 % to 80 % of the full scale reading, although values based on readings taken outside these limits may be noted in the report. Raise the pendulum to its initial position and secure it by the pendulum release mechanism. Carefully position the test piece in the clamps so that the slit, if pre-made, is centrally situated be- tween the clamp on the frame and the clamp on the pendulum, and tighten the clamps. Where applica- ble, operate the knife to produce the required slit. Set the pointer if fitted, against its stop. Sharply depress the pendulum release mechanism and holding it down, gently catch the pendulum by hand on its return swing without disturbing the po- sition of the pointer, if fitted. Record the scale read- ing to the nearest scale division for the capacity used. NOTE 4 Digital read-out instruments may have slightly different arrangements for releasing and arresting the pendulum. In such cases follow the manufacturer’s in- structions. Return the pendulum and, if fitted, the pointer to the initial position and remove the torn paper. Repeat this procedure for the other test pieces, orientating them so that side one faces towards and away from the pendulum alternately. The path of the tear may deviate from the direction of the slit. If the mean deviation exceeds IO mm in one or two out of IO tests, reject these results and carry out further tests to bring the number of satis- factory tests up to 10. If in more than two of the test pieces the deviation exceeds IO mm, include the results and state the fact in the test report. If, instead of tearing in the normal way, the paper of any test piece peels apart so as to expose a wide 2 SIST EN 21974:2000
IS0 1974:1990(E) band of torn surface (the effect known as “skinning”), apply the criteria in the preceding par- agraph to the mean centre line of the torn band through the test pieces. If the tearing resistance of the paper or board or the available pendulum or pendulum/augmenting mass combination is such that satisfactory results cannot be obtained using a test piece made up of four sheets, tests may be carried out using more or fewer sheets. State this fact clearly in the test report. NOTES 5 The apparent tearing resistance is dependent on the number of sheets torn simultaneously. With some papers, the difference in apparent tearing resistance when one and four plies are torn simultaneously may exceed 20 O/o. Comparison between four plies and two or more plies (up to 16) shows smaller differences than between one and four plies, but these differences may still be significant. 6 If the sheets curl, ensure that they lean towards and not away from the pendulum, by bending them gently at the clamp. In doing so, avoid affecting the moisture con- tent of the test areas. 10 Calculation and expression of results For each direction tested, calculate the mean scale reading and, from the following equations, the tear- ing resistance and the tear index: r r;/, 4=- ?I X r --- - i where F - I 7 P ?I X g is the tearing resistance, expressed in millinewtons; is the mean scale reading, expressed in millinewtons; is the number of sheets torn simultane- ously for which the pendulum scale has been calibrated to give a direct tearing resistance reading, in millinewtons (commonly the va.lue of this factor is 4, 8, 16 or 32); is the number of sheets torn simultane- ously (normally four); is the tear index, expressed in millinewton square metres per gram (mN.m*/g); is the grammage, expressed in grams per square metre, and determined in ac- cordance with IS0 536. Calculate the coefficient of variation of the results from the individual scale readings. 11 Precision Regular comparative testing in the USA, involving 120 laboratories testing 12 papers, indicated the re- peatability of the method to be about 3,5 %. The same comparison indicated the reproducibility to be about 18 %. 12 Test report The test ulars: shall include the following partic- a) reference to this International Standard; b) date and place of testing; c) description and identification of material tested; d) th e direct di rection) ion of the test (machine direction, cross e) the number of replicate tests carried out, if other than 10; f) the tearing resistance, in millinewtons, and the tear index, in millinewton square metres per gram, to three significant figures, in the direction tested; g) the coefficient of variation of results; h) the manufacturer, model number and pendulum factor @) of the apparatus; 0 the number of sheets torn simultaneously; j) any deviation in tear from the correct path, or whether extensive “skinning” occured; NOTE 7 Tests in which these effects have occurred may give spuriously high or low results, which should be in- terpreted with great caution. k) any other departures from this International Standard or other circumstances which may have had an influence on the results; I) the grammage of the paper or any other factor which may assist in interpretation of the results. SIST EN 21974:2000
IS0 1974:1990(E) Annex A (normative) Description, adjustment and maintenance of single tear testers A.1 Description The apparatus consists of a frame, mounted on a rigid base, carrying a pendulum and pointer assem- bly (see figureA.l). Two clamps, one on the frame and one on the pendulum are provided to hold the test piece. The clamping surfaces shall be at least 25 mm wide and 15 mm deep. The pendulum is free to swing on an essentially frictionless bearing about a horizontal axis. NOTE 8 On some apparatus the pointer assembly has been replaced by a transducer/digital read-out system but in other respects conforms to the requirements of this annex. When the pendulum is in its initial position, ready for test, the
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