1、BRITISH STANDARD BS3424-25: 1993 Testing coated fabrics Part 25: Method 28. Method for determination of the coating thickness and thickness of any expanded layer IMPORTANT NOTE.It is recommended that this Part be read in conjunction with the information in Part0 “Foreword and general introduction”.B
2、S3424-25:1993 This British Standard, having been prepared under the direction of the Plastics andRubber Standards Policy Committee, was published underthe authority of the Standards Board and comesintoeffect on 15 May 1993 BSI06-1999 The following BSI references relate to the work on this standard:
3、Committee reference PRM/78 Draft for comment91/43365DC ISBN 0 580 21730 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Information Technology Systems Standards Policy Committee (PRM/-) to Technical Committee PRM/78, upon which the fol
4、lowing bodies were represented: British Nonwovens Manufacturers Association British Plastics Federation British Railways Board British Resin Manufacturers Association British Rubber Manufacturers Association Ltd. British Textile Confederation British Textile Technology Group Department of Health Dep
5、artment of the Environment (Building Research Establishment) Electricity Industry in United Kingdom Furniture Industry Research Association Home Office Industrial Safety (Protective Equipment) Manufacturers Association London Regional Transport Made-up Textiles Association Ministry of Defence Nation
6、al Union of Dyers, Bleachers and Textile Workers (NUDBTW) RAPRA Technology Ltd. SATRA Footwear Technology Centre Society of Motor Manufacturers and Traders Ltd. The following body was also represented in the drafting of the standard, through subcommittees and panels: Ministry of Defence Amendments i
7、ssued since publication Amd. No. Date CommentsBS3424-25:1993 BSI 06-1999 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1 Scope 1 2 References 1 3 Principle 1 4 Apparatus 1 5 Preparation of test specimens 1 6 Calculation and expression of results 2 7 Test report
8、 2 List of references Inside back coverBS3424-25:1993 ii BSI 06-1999 Foreword This Part of BS3424 has been prepared under the direction of the Plastics and Rubber Standards Policy Committee. The present method is intended for use as a check-test on coating thickness and is not intended for use as qu
9、ality test against which specifications could be attributed. Also, because of the small specimen size, the sampling procedure and some statistical analysis of results is advisable. In this regard attention is drawn to BS600 and BS2846. It is hoped that in the future a non-destructive method of deter
10、mining coating thickness, at least on single-faced coated fabrics, will be available. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of it
11、self confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1and2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indi
12、cated in the amendment table on theinside front cover.BS3424-25:1993 BSI 06-1999 1 Introduction The thickness of the polymer coating applied to a textile substrate is of critical importance, as it determines, all else being equal, how that coated fabric will perform in use. It is not however a facto
13、r that is commonly measured, as it is the actual performance characteristics of the coated fabric that are important. If the coating thickness is insufficient or too great, then the coated fabric will fail to perform in one or more of its physical attributes or during fabrication. However, for resea
14、rch, production planning or production cost control purposes, the coating thickness is a feature that may be required to be measured. It is included here for that purpose, but it is recommended that the method is not cited in any specification for coated fabrics. The difficulties encountered in meas
15、uring the coating thickness depend upon the composition and colour of the coating polymer, textile substrate, whether there is an expanded layer included, the method of applying the coating polymer and the thickness of the coating. Various methods of measuring the coating thickness are available. Th
16、ese include: a) sectioning techniques using a microtome or other sectioning device and direct measurement under a microscope with a calibrated eyepiece graticule; b) the use of a scanning electron microscope which may provide additional information for particular circumstances. Methods employing emb
17、edding techniques such as those specified in method 28B of BS3424:1973 introduce chemical elements that may cause damage or swelling of the coating polymer and are therefore unreliable for universal application. 1 Scope This Part of BS3424 describes a method for determining the thickness of the poly
18、mer coating and of an expanded layer, if present, of a coated fabric. 2 References 2.1 Normative reference This Part of BS3424 incorporates, by reference, provisions from a specific edition of another publication. This normative reference is cited at the appropriate point in the text and the publica
19、tion is given on the inside back cover. Subsequent amendments to, or revisions of, this publication apply to this Part of BS3424 only when incorporated in it by updating or revision. 2.2 Informative references This Part of BS3424 refers to other publications that provide information or guidance. Edi
20、tions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Principle Either, a cut perpendicular to the finished surface of the coated fabric is made through a specimen, or a microscopic sectio
21、n is cut using a simple hand microtome. The cut or section is then examined by means of a binocular microscope using a stage micrometer and the thickness of the coating is measured. 4 Apparatus 4.1 Binocular microscope, giving a magnification of at least X15, (the preferred magnification being X50),
22、 incorporating an eye-piece graticule graduated in divisions of0.01mm or line profilometer and top lit stage for surface illumination. 4.2 Stage micrometer, to calibrate the eye-piece graticule at the magnification used. 4.3 Hand microtome, or other means of sectioning or cutting through the coated
23、fabric without using an embedding technique whilst ensuring that the cut is normal to the surface of the coated fabric. 4.4 Stand, for supporting the section of the coated fabric under the microscope objective. 4.5 One black and one white contrast background, to provide opposing shade contrasts to t
24、he coatings. 5 Preparation of test specimens Prepare five test specimens, one from each of five subsamples, evenly spaced diagonally across the full width of the sample as follows: Cut a section perpendicular to the finished surface of the coated fabric using either the microtome(4.3) or a sharp sca
25、lpel or blade. After sectioning the coated fabric allow the test pieces to recover from any induced strain for24h in an atmosphere conforming to BS3424-2:1993. NOTEIn order to render the boundary between the coating and the substrate more distinguishable, it has been found helpful to apply a light d
26、usting of fine powder in a contrasting colour to the edge being viewed. Excess powder may be wiped off so that the smoother edge of the cut surface is left clean. Mount the cut test specimen so that the cut edge is uppermost and place it on the microscope stage so that its coated edge is adjacent to
27、 the contrasting surface(4.5) of its support.BS3424-25:1993 2 BSI 06-1999 Focus the microscope on the edge of the test specimen. Rotate either the section or the eyepiece until one of the major graduations is aligned with the bottom surface of the coating or expanded layer, as appropriate. Where the
28、 coating/substrate or skin coat/expanded layer interface undulates, the graduation should be positioned so that it lies midway between the peaks and troughs. Measure the thickness of the coating (or expanded layer) in terms of the graduations (i.e.to the nearest0.01mm) relative to the bottom surface
29、 of the coating. Repeat this procedure in at least three, evenly spaced positions, on each test specimen for both skin coat and expanded layer (if present). Where the coating is embossed, measure both the maximum and minimum thickness of coating over the upper surface of the textile. If the fibrous
30、or yarn layer of the textile substrate is hairy, report the thickness of the coating from the main body of the textile substrate as the maximum coating thickness and the thickness of coating over the highest fibre layer as the minimum coating thickness. Where the coating is embossed, measure both th
31、e maximum and minimum thickness of coating over the upper surface of the textile. If the fibrous or yarn layer of the textile substrate is hairy, report the thickness of the coating from the main body of the textile substrate as the maximum coating thickness and the thickness of coating over the hig
32、hest fibre layer as the minimum coating thickness. Calibrate the microscope eyepiece gradations by placing the stage micrometer under the microscope, and record the distance between the graticule marks of the eyepiece. 6 Calculation and expression of results Record all15 values and calculate the ari
33、thmetic mean to the nearest0.01mm of the three measurements made on each test specimen and the arithmetic mean from the five arithmetic means and the95% confidence interval of the mean (see BS2846-2). Express the results to the nearest0.01mm. 7 Test report The test report shall include the following
34、 particulars: a) the description of the coated fabric; b) the individual results of the observations of the coating thickness,(n =15), the arithmetic mean of all the results and the confidence interval of the mean; c) the individual results of the observations of thickness of the expanded layer, if
35、any, (n=15), and the arithmetic mean of the results; d) reference to this method of test, i.e.method28 of BS3424-25:1993; e) any observations relating to difficulties of measurement, e.g.extremely thin coating embedded in the textile substrate, difficulty of differentiating colours of skin coat from
36、 that of the expanded layer or textile substrate, etc; f) details of any deviations from the standard test procedure.BS3424-25:1993 BSI 06-1999 List of references (see clause2) Normative reference BSI standards publications BRITISH STANDARDS INSTITUTION, London BS3424, Testing coated fabrics. BS3424
37、-2:1982, Method 4. Conditioning and selection of test specimens. Informative references BSI standards publications BRITISH STANDARDS INSTITUTION, London BS600:1935, The application of statistical methods to industrial standardization and quality control 1) . BS2846, Guide to statistical interpretati
38、on of data. BS2846-2:1981, Estimation of the mean: confidence interval. 1) Referred to in the foreword only.BS3424-25: 1993 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view
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