1、BRITISH STANDARD BS 2571:1990 Specification for General-purpose flexible PVC compounds for moulding and extrusionBS 2571:1990 This British Standard, having been prepared under the directionof the Plastics StandardsPolicy Committee, waspublished under the authorityof the Board of BSI andcomes into ef
2、fect on 30 April1990 BSI 03-1999 First published March 1955 Second edition October 1963 Third edition April 1990 The following BSI references relate to the work on this standard: Committee reference PLM/42 Draft for comment 87/42851 DC ISBN 0 580 18087 5 Committees responsible for this British Stand
3、ard The preparation of this British Standard was entrusted by the Plastics Standards Policy Committee (PLM/-) to Technical Committee PLM/42, upon which the following bodies were represented: British Plastics Federation British Rubber Manufacturers Association Packaging and Industrial Films Associati
4、on SATRA Footwear Technology Centre Amendments issued since publication Amd. No. Date of issue CommentsBS 2571:1990 BSI 03-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Composition 1 3 Classification 1 4 Colour fastness 1 5 Colour bleeding 1 6 Appearance 1 7
5、Physical property requirements 1 8 Marking 1 Appendix A Preparation of milled and moulded sheets and test specimen conditioning 3 Appendix B Relationship between weathering and the different grades of colour fastness 4 Table 1 Physical properties of injection moulding compounds 2 Table 2 Physical pr
6、operties of extrusion compounds 2 Table 3 Relationship between softness number and the surface temperatures of mill rolls and moulds 3 Publications referred to Inside back coverBS 2571:1990 ii BSI 03-1999 Foreword This British Standard has been prepared under the direction of the Plastics Standards
7、Policy Committee. It is a revision of BS2571:1963 which is superseded and withdrawn. Classes1 and2 materials for which electrical properties were specified have been deleted from this revision and have now been included in BS6746. Since there is now only one class of materials these are no longer re
8、ferred to as “Class3 materials”. The classification in the standard therefore now only contains12 types, i.e. M1 to M6, with increasing softness for moulding and a similar but not identical range, E1 to E6, for extrusion applications. In this revision, M1 and E1 types correspond to type G1 Class3 co
9、mpounds of the previous edition of the standard. Similarly, M2, E2 correspond to G2 and so on. New types of E6 and M6 have been added. In addition, grading according to colour fastness has been introduced together with an additional Appendix B to explain the relationship between weathering and the d
10、ifferent grades of colour fastness. The test methods have been updated and aligned where possible with ISO test methods. 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 wit
11、h a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amend
12、ments incorporated. This will be indicated in the amendment table on theinside front cover.BS2571:1990 BSI 03-1999 1 1 Scope This British Standard specifies the composition and property requirements for12 types of general-purpose flexible PVC compounds M1 to M6 used for injection moulding, and E1 to
13、 E6 used for moulding and extrusion applications. NOTE 1Chlorinated PVC compounds are not included in this standard. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Composition Compounds shall be manufactured from homopolymers of vinyl chlorid
14、e and shall be compounded with plasticizers and other ingredients. 3 Classification Compounds shall be classified into12 types, M1 to M6 and E1 to E6, for moulding and extrusion applications respectively (seeTable 1 and Table 2). Additionally each type shall be subdivided into three grades A, B or C
15、 to indicate colour fastness to daylight (see4.1), to artificial light (see4.2), or no colour fastness (see4.3) respectively. 4 Colour fastness 4.1 Colour fastness to daylight: grade A Compounds graded as A shall have a colour fastness to daylight of not less than blue-dyed wool standard No.4, when
16、sheet prepared as described in Appendix A is tested in accordance with BS2782-5:Method 540A. NOTEExperience has shown that this requirement is sufficient to ensure no serious colour change after18 months of typical outdoor exposure in the UK. Plasticized PVC compounds with better colour fastness to
17、daylight can be obtained by careful selection of the pigments and other ingredients. These “special” compounds and their properties should be the subject of direct discussion with the supplier. 4.2 Colour fastness to artificial light: grade B Compounds graded as B shall have a colour fastness to art
18、ificial light of not less than blue-dyed wool standard No.4, when sheet prepared as described in Appendix A is tested in accordance with BS2782-5:Method 540B, provided that: a) a xenon arc lamp filtered so as to simulate solar radiation is used; b) lamps and filter are changed at the intervals recom
19、mended by the manufacturers; c) specimen holders rotate on their axes as well as rotating about the lamp; d) a black panel temperature of55 3C is used; e) the relative humidity is50 5%; f) specimens are not sprayed directly with distilled water or deionized water used to maintain50 5%r.h. 4.3 No col
20、our fastness: grade C Compounds graded as C shall be all materials not able to comply with the colour fastness requirements of either 4.1 or 4.2. 5 Colour bleeding There shall be no colour bleeding when sheet prepared as described in Appendix A is tested in accordance with BS2782-5:Method 542A. 6 Ap
21、pearance The compounds shall be free from foreign matter and uniform in colour. The colour of the sheet moulded as described in Appendix A shall be accepted as the colour of the compound. 7 Physical property requirements The physical properties shall comply with Table 1 and Table 2 when specimens fr
22、om sheet prepared as described in Appendix A are tested using the methods listed therein. 8 Marking The label or delivery document shall contain at least the following information: a) the manufacturers name or trade mark; b) the classification of the material (see clause 3), e.g. E4A; c) the number
23、and date of this British Standard, i.e. BS2571:1990 1) . 1) Marking BS2571:1990 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim for or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is
24、 therefore solely the responsibility of the person making the claim. Such a declaration is not to be confused with third party certification of conformity which may also be desirable.BS2571:1990 2 BSI 03-1999 Table 1 Physical properties of injection moulding compounds Table 2 Physical properties of
25、extrusion compounds Property Unit Method from BS 2782 Type of compound M1 M2 M3 M4 M5 M6 Softness Softness number 365A 80 Tensile strength MPa min. 320A a 15 14 12.5 10.5 8 7 Elongation at break % min. 320A a 150 200 250 275 300 325 Cold bend temperature C max. 151A 10 15 25 30 40 45 Cold flex tempe
26、rature C max. 150B +15 +5 5 10 20 30 Plasticizer loss on heating % max. 465B 1.5 1.5 2.0 2.5 3.0 4.0 a Test carried out with a rate of grip separation of 500 mm/min. Property Unit Method from BS 2782 Type of compound E1 E2 E3 E4 E5 E6 Softness Softness number 365A 80 Tensile strength MPa min. 320A a
27、 19 17 14 11 9 7.5 Elongation at break % min. 320A a 150 200 250 300 325 350 Cold bend temperature C max. 151A 10 15 25 30 40 45 Cold flex temperature C max. 150B +15 +5 5 10 20 30 Plasticizer loss on heating % max. 465B 1.5 1.5 2.0 2.5 3.0 4.0 a Test carried out with a rate of grip separation of 50
28、0 mm/min.BS2571:1990 BSI 03-1999 3 Appendix A Preparation of milled and moulded sheets and test specimen conditioning A.1 Principle Initially milled sheets are prepared which are subsequently bonded under pressure to provide moulded sheets from which test specimens are die-cut. A.2 Apparatus A.2.1 T
29、wo-roll mixing mill, with cylindrical rolls and capable of operating at temperatures up to and including180C. A.2.2 Hydraulic moulding press, capable of developing a moulding pressure of at least10MPa. Press platens shall be equipped with means of heating and cooling such that the platen surfaces ca
30、n be heated to a temperature of180 with the maximum deviation of temperature at any point within the moulding area not exceeding 3 C from the temperature at the centre of the platen. A.2.3 Moulds, male, female and “window-frame” equipped with several parting foils, e.g. highly polished photographic
31、steel plates. A.2.4 Cutting die, with sharp edges free from defects such as notches and burrs. A.3 Procedure A.3.1 Preparation of milled sheet materials Prepare sheets of material using the two-roll mill as follows. Set the speed of the slower mill roll at10 2m/min. Set the surface temperatures of t
32、he rolls in the range shown inTable 3according to the softness number of the materials determined using BS2782-3:Method 365A, such that after1 to2min of milling, the material will band on the rolls. NOTEIt is normal for there to be a differential speed between the two mill rolls. The preferred ratio
33、 is1:1.2, the working roll being the slower. Table 3 Relationship between softness number of the materials and the surface temperatures of mill rolls and moulds Set the nip setting so as to produce the desired thickness of the milled sheet. The sum of the thickness of all the sheets to be used for m
34、oulding shall be slightly greater than the thickness of the moulded sheet, or test specimen, required. Add the material to the mill rolls. Ensure that the material forms a rolling bank to obtain effective mixing. Any material falling through the nip shall be carefully and quickly collected from the
35、tray and returned to the moving mill rolls. Once a sheet is formed, continue milling for approximately5min in such a way that optimum dispersion of all material components is obtained. This normally includes cutting the sheet, allowing it to form a roll or flap and refeeding this to the rolling bank
36、 in the nip. Remove the milled sheet from the rolls without stretching. NOTESignificant deviations from these milling procedures can affect the physical property levels obtained. A.3.2 Preparation of moulded sheet materials Determine the required mass of material required to fill the mould either by
37、 calculation from the sheet material density or by making a trial moulding. Place the required number of milled sheets, preferably cross layered, in the mould preheated to a temperature appropriate to the softness number of the materials (Table 3). Close the preheated platens of the press and mainta
38、in a pressure of approximately0.3MPa for5min to faciliate preheating of the material. Then increase the mould pressure to between2MPa and10MPa and maintain this pressure for2min to5min. During this time there shall be sufficient flow of material between the mould and the metal surfaces to result in
39、the formation of a small amount of moulding flash. Cool the mould to approximately40C or, in the case of very soft materials, to a lower temperature, while maintaining constant the applied pressure. Open the mould and remove the sheet. A.3.3 Preparation of test specimens Prepare the required test sp
40、ecimens from the moulded sheet not less than48h after manufacture by machining or stamping, using a sharp die (A.2.4) of the required shape. Where specimens are required for measuring softness the minimum time after manufacturing shall be7 days. A.3.4 Conditioning and testing conditions Carry out co
41、nditioning and all testing at23 2 C and50 5%r.h. unless the relevant test method specifies otherwise. Condition for48h prior to testing except for the determination of softness number, where the conditioning period shall be7days. Softness no. of the materials Surface temperature Mill rolls Moulds C
42、C30 130 to 160 135 to 165BS2571:1990 4 BSI 03-1999 Appendix B Relationship between weathering and the different grades of colour fastness It is emphasized that colour fastness is not the same as weathering, where the effects of direct sunlight and rain are present. Colour fastness tested in accordan
43、ce with BS2782-5:Method 540A uses specimens exposed in an outdoor rack, facing south in the northern hemisphere, inclined at45, under3mm thick glass. The glass filters out some of the sunlight, especially at the lower wavelengths of the spectrum, i.e. the ultraviolet components. Ultraviolet light is
44、 damaging to polymers such as PVC and can cause changes in colour, depending upon the pigmentation systems used. The small amount of ultraviolet light in sunlight can vary quite markedly with geographic location, with height above sea level, cloud cover, the degree of pollution and the season of the
45、 year. For these reasons, determinations of colour fastness to natural light, even when blue-dyed wool standards are used, can produce variable results. Controlled determination of colour fastness to artificial light, i.e. when tested in accordance with BS2782-5:Method 540B, can be less variable but
46、 the various laboratory light sources available produce different results from each other. The xenon arc illuminant has been recommended in this standard because, in its commonly used forms, its spectral output is similar to daylight and it has been widely used for more than30 years. Results are usu
47、ally obtained in a third or a quarter of the time taken to determine colour fastness to natural light. Results of colour fastness tested with artificial and natural light should not be expected to be exactly the same. The ultraviolet levels in laboratory light sources can be higher than in natural l
48、ight thereby providing a more stringent test, bearing in mind the greater inherent variability of natural light.BS 2571:1990 BSI 03-1999 Publications referred to BS 2782, Methods of testing plastics. BS 2782-1, Thermal properties. BS 2782:Method 150B, Determination of cold flex temperature of flexib
49、le polyvinyl compound. BS 2782:Method 151A, Determination of cold bend temperature of flexible polyvinyl chloride extrusion compound. BS 2782-3, Mechanical properties. BS 2782:Method 320A to Method 320F, Tensile strength, elongation and elastic modulus. BS 2782:Method 365A, Determination of softness number of flexible plastics materials. BS 2782-4, Chemical properties. BS 2782:Method 465A and Method 465B, Determination of loss of plasticizers (activated carbon method). BS 2782-5, Optical and colour properties, weather
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