1、BRITISH STANDARD BS 5350-H4: 1984 Methods of test for Adhesives Part H4: Determination of maximum open time of hot-melt adhesives (ovenmethod) UDC 665.93:620.193.91BS5350-H4:1984 This British Standard, having been prepared under the directionof the Adhesives Standards Committee, was published under
2、the authority ofthe Board of BSI and comes intoeffect on 29 February 1984 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference ADC/9 Draft for comment 81/54127 DC ISBN 0 580 13648 5 Amendments issued since publication Amd. No. Date of issue CommentsBS5350
3、-H4:1984 BSI 08-1999 i Contents Page Foreword ii 0 Introduction 1 1 Scope and field of application 1 2 Definition 1 3 Principle 1 4 Supplementary information 1 5 Apparatus 1 6 Test materials 1 7 Procedure 2 8 Expression of results 2 9 Test report 2 Figure 1 Steel block 3 Figure 2 Folded upper test p
4、iece 3 Figure 3 Plan view of lower test piece with adhesive (shaded) in position 3 Figure 4 Test assembly showing location of upper test pieces prior to rupture test 4 Publications referred to Inside back coverBS5350-H4:1984 ii BSI 08-1999 Foreword This Part of this British Standard has been prepare
5、d under the direction of the Adhesives Standards Committee. It is one of a series of methods for the assessment of physical properties of hot-melt adhesives published as separate Parts of group H of this standard. This method offers a simple procedure by which open times of different hot-melt adhesi
6、ves may be compared. An alternative procedure using a wheel applicator device is described in Part H5 1)of this standard. WARNING NOTE. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to tec
7、hnical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. 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 B
8、ritish 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, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendment
9、s incorporated. This will be indicated in the amendment table on the inside front cover. 1) In course of preparation.BS5350-H4:1984 BSI 08-1999 1 0 Introduction The performance of hot-melt adhesives in practical situations can be influenced by variations in their open times (seeclause2). The maximum
10、 open time of a given hot-melt adhesive is dependent on the temperature of application, the amount and configuration of the adhesive applied, the type of substrate, its temperature and the ambient conditions. Carton board is used as the adherend in this method because it provides a convenient substr
11、ate in which bond failure can be observed. Valid comparative tests of adhesives in other applications can then be made using this substrate for ranking purposes. 1 Scope and field of application This Part of this British Standard describes a subjective test method designed to give a rapid estimate o
12、f the maximum open time of a hot-melt adhesive under specified test conditions. The method is suitable for hot-melt adhesives which are sufficiently stable to enable a film to be prepared and is independent of the viscosity of the adhesive. The results by this method may not necessarily indicate the
13、 performance of the adhesive in any particular service condition. NOTEThe publications referred to in this British Standard are listed on the inside back cover. 2 Definition For the purposes of this Part of this British Standard the following definition applies. maximum open time the time interval a
14、fter application of the adhesive to one adherend surface during which a second surface can be satisfactorily bonded to the first 3 Principle A previously prepared film of adhesive is melted in an oven on a carton board substrate at a specified temperature. The coated substrate is removed from the ov
15、en and whilst the adhesive is cooling a series of joints are made using further pieces of carton board at increasing time intervals. When cool, the joints are peeled apart by hand and the mode of failure observed. The greatest time interval for which the bond formed will still give100% tearing of th
16、e fibre surface of the board during separation is taken as the maximum open time of the adhesive. 4 Supplementary information This method of test requires the following supplementary information which shall be specified when this method is called up. a) Details of the carton board to be used includi
17、ng any specified properties. b) The temperature of the test oven. c) The period after removal from the oven at which joints are to be made and the testing interval. 5 Apparatus 5.1 Normal laboratory apparatus 5.2 Oven, fitted with a circulation fan and capable of maintaining a temperature to within
18、2 C over a range of temperature appropriate to the melting point of the test adhesive. 5.3 Steel blocks, of 20mm square cross section and mass200g (seeFigure 1). 5.4 Rubber pad, not less than200mm 50mm and at least10mm thick of hardness approximately IRHD70(seeBS903-A26). 5.5 Roller, adjustable roll
19、ers, or other suitable equipment for preparation of adhesive film. 5.6 Stopwatch or timer, accurate to0.1s. 6 Test materials 6.1 Adherend. The adherend shall be carton board of suitable surface strength 2)(see note). The material to be used shall be specified when this method is called up. Unless ot
20、herwise specified the carton board shall be white lined chipboard of thickness about5004m. NOTEThe test is comparative and the result will depend on the cohesive strength of the board surfaces and their ability to be wetted by molten adhesive. The surface strength may be characterized by specifying
21、the wax pick number determined according to the method described in ASTM Method D2482-76. Separate test results will be required for the lined and unlined surfaces of the board. It is not however possible to specify a particular wax pick number. A suitable value is one which provides a joint that sh
22、ows a sharp transition from complete fibre tear to no tear in the test. 6.2 Preparation of test pieces. Condition the adherend before testing for24h at a temperature of23 2 C and505%r.h. Determine the machine direction of the board sample. This may be done by cutting a square from the edge of the bo
23、ard as supplied and flexing it in each direction in turn. The direction of the curve showing the greater rigidity is the machine direction. 2) Information on the availability of a suitable material is available on application to the Enquiry Section (London), British Standards Institution.BS5350-H4:1
24、984 2 BSI 08-1999 For each series of tests cut a test piece200mm 50mm with the longer dimension parallel to the machine direction. Cut at least five smaller test pieces70mm 20mm with the shorter dimension parallel to the machine direction. 6.3 Preparation of adhesive film. Gently heat a quantity of
25、adhesive until molten and maintain it in this state until any entrained air has been removed. Prepare a uniform film from the molten adhesive0.5 0.1mm thick and of sufficient length and width to allow several strips190mm 25mm to be cut from it. A recommended method for preparing the film is to sandw
26、ich a quantity of the molten adhesive between two layers of a suitable release paper which has been previously dried at a temperature of60 C to80 C for30min. Pass the composite through a pair of adjustable rollers, allow the film to cool and remove the release papers. 7 Procedure The oven temperatur
27、e and the testing interval will normally be given as supplementary information (seeclause4) and the procedure is described in terms of a value to be specifed for these parameters. In the absence of specified values a temperature of160 2 C and a time interval of5s shall be used for initial testing. T
28、ake a suitable number of the smaller test pieces (see6.2) and fold each around a steel block (5.3) as shown inFigure 2 with the unlined surface outward. Cut from the adhesive film (see6.3) a strip190mm 25mm and place it on the lined surface of the200mm 50mm test piece (see6.2) as shown in Figure 3.
29、Transfer the assembly to the preheated oven and maintain it at the specified test temperature for5min. To prevent curling of the assembly during heating restrain the ends of the board with clips or preheated weights. At the end of the5min period remove the assembly from the oven and place it board s
30、ide down on the rubber pad (5.4). Locate the pad so that it is under draught-free conditions. Start the timer. After the specified time interval, place one of the folded test pieces with the unlined surface in contact with the adhesive and hold it down with one of the steel blocks (seeFigure 4). Rep
31、eat this operation after successive further time intervals, placing the successive test pieces along the adhesive strip as shown inFigure 4. Leave the assembly for15min after the last test piece has been applied. Then remove the steel blocks and peel off each bonded upper test piece by pulling slowl
32、y on one end whilst restraining the lower board test piece, taking2sto3s for each peeling operation. Maintain the pull at right angles to the lower board test piece as the bond parts. Examine the surface of the test pieces and estimate the percentage of fibre tear over each contact area. NOTEFibre t
33、ear implies destruction of part or the whole of the board surface and should not be confused with plucking or pulling away of separate fibres. For the test to be valid there has to be a transition from complete fibre tear to no fibre tear in a sequence of peel trials. If the test is invalid repeat t
34、he series using suitable variation of the time interval or if appropriate, the test temperature until a time can be identified which corresponds to100% fibre tear. Once a valid test result has been obtained repeat the tests under the same conditions to obtain at least three valid tests. 8 Expression
35、 of results Take the maximum open time of the adhesive under the specified conditions of test as the total time interval between removal of the assembly from the oven and the application of the upper test piece for which complete tearing of the board surface is obtained. Report the values of all val
36、id test results and not their arithmetic mean. 9 Test report The report shall state the following: a) a designation of the adhesive giving all information necessary for complete identification of the sample; b) the items of supplementary information given inclause4; c) the test result; d) that the m
37、ethod of test complied with the requirements of this standard, i.e. BS5350-H4, or, if it did not, the respects in which it did not comply.BS5350-H4:1984 BSI 08-1999 3 NOTEDimension “x” to be adjusted to give mass of 200 1 g. All dimensions are in millimetres. Figure 1 Steel block NOTEPosition of ste
38、el block indicated by broken lines. All dimensions are in millimetres. Figure 2 Folded upper test piece m is the machine direction All dimensions are in millimetres. Figure 3 Plan view of lower test piece with adhesive (shaded) in positionBS5350-H4:1984 4 BSI 08-1999 Figure 4 Test assembly showing l
39、ocation of upper test pieces prior to rupture testBS5350-H4:1984 BSI 08-1999 Publications referred to BS 903, Methods of testing vulcanized rubber. BS 903-A26, Determination of hardness. BS 5350, Methods of test for adhesives. BS 903-H5, Determination of maximum open time of hot-melt adhesives (Whee
40、l applicator method) 3) . ASTM Method D 2482-76 Wax pick test for surface strength of paper, Annual Book of ASTM Standards1982-20. 3) In course of preparation.BS 5350-H4: 1984 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for
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