ISO INTERNATIONAL STANDARD 498 Second edition 1992-03-15 Natural rubber latex concentrate -- Preparation of dry films Latex concentre de caoutchouc naturel -- Preparation de pellicules seches Reference number ISO498:1992(E) Copyright International Organization for Standardization No reproductin or netvorking perminted withou license fro IHs Not for Resale ISO 498:1992(E) Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing Internationai Standards is normally carried out through iso 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- work. IsO 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 voting. Publication as an Inter- bodies casting a vote. International Standard isO 498 was prepared by Technical Committee isO/Tc 45, Rubber and rubber products, Sub-Committee Sc 3, Raw ma- This second edition cancels and replaces the firstedition 498:1974), of which it constitutes a minor technical revision. ISO1992 or by any means, electronic or mechanical, including photocopying and microfilm, without permlssion in writing from the publisher. International Organization for Standardization Case Postale56·CH-1211Geneve20·Switzerland PrintedinSwitzerland Noreproductionornetworkingpermitedwithout licensefromIHS Not for Resale ISO 498:1992(E) INTERNATIONAL STANDARD Natural rubber latex concentrate -- Preparation of dry films Scope Adhesives suitable for affixing the strips to the gliass are epoxide resin adhesives, and poly(vinyl acetate) This International Standard specifies a method for dissoived in methyl ethyi ketone. Such a mould wil! homogeneous films. substantially give dry films about 1 mm thick when filled with la- preparing dry, free of air bubbles, from natural rubber latex con- tex of 62 % (m/m) total solids content. centrate. 3.2 Square-mesh gauze, of polyamide or stainless The procedure is not necessarily suitable for latices steel, with average aperture width of from natural sources other than Hevea brasiliensis 180 μm ± 10 μm, for straining the latex. or for compounded latex, vulcanized latex or arti- ficial dispersions of rubber or synthetic rubber 3.3 Straightedge, wooden, piastic or stainless steel, latices. with which to scrape the surface of the latex in the mould free of air bubbles. 2 Normative references 3.4 Cabinet or covered space, clean, dry and dust- free, with a levei surface on which to place the The following standards contain provisions which, mould. throughreferenceinthistext,constituteprovisions ofthisinternationalStandard.Atthetimeofpubli- 3.5 Oven, capable of maintaining a temperature of cation, the editions indicated were valid. All stan- 35 °℃ ± 2 °℃. dards are subject to revision, and parties to agreements based on this International Standard 3.6 Cellulosic-film sheets, thin, clear and trans- are encouraged to investigate the possibility of ap- parent, to cover and protect the dry film. plying the most recent editions of the standards in- dicated below. Members of IEC and ISO maintain registers of currently valid international Standards. 3.7 Desiccator or airtight container, for storing the dry film. ISO123:1985,Rubberlatex- Sampling. 3.8 Beaker, of suitable capacity, e.g. 50 cm3. Iso124:1992,Rubberlatices--Determinationoftotal solids content. 4 Sampling Carry out the sampling in accordance with one of 3 Apparatus the methods specified in Iso 123. 3.1 Suitable mould, in which the film can be cast, 5 Procedure prepared by cementing strips of glass or a rigid plastic material 6 mm wide and 1,5mm thick on a Determine the total solids content of the iatex in ac- fla