1、T 821 om-12 PROVISIONAL METHOD 1981 OFFICIAL TEST METHOD 1987 REVISED 1996 REVISED 2006 REVISED 2012 2012 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and the Association assume no liability or responsibility in co
2、nnection with the use of such information or data, including but not limited to any liability under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published. Approved by the Standard Specific Interest Group for this Test
3、 Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of the method. The intent of these is to alert the user of the method to safety issues related to such use. The user is responsible for determining that the safety p
4、recautions are complete and are appropriate to their use of the method, and for ensuring that suitable safety practices have not changed since publication of the method. This method may require the use, disposal, or both, of chemicals which may present serious health hazards to humans. Procedures fo
5、r the handling of such substances are set forth on Material Safety Data Sheets which must be developed by all manufacturers and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemicals. Prior to the use of this method, the user must determine
6、 whether any of the chemicals to be used or disposed of are potentially hazardous and, if so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal of these chemicals. Pin adhesion of corrugated board by sel
7、ective separation 1. ScopeThis method is used to measure the force required to separate corrugated board between the flute tips of corrugated medium and its linerboard facings. 2. Significance 2.1 Good adhesion of the corrugated medium to its facings is important in obtaining high quality corrugated
8、 board and boxes. The pin-adhesion test provides a means of determining the nature and strength of the bond formed during the combining operation and may be used to detect some manufacturing defects, such as poor adhesive penetration, spotty adhesion, and containerboard with a low internal bond stre
9、ngth. 2.2 The test described in this procedure will measure the Z-direction force required to separate selectively either the inside or outside facing of corrugated board. NOTE 1: A defect exists in this test which can cause low readings, especially with lightweight liners. When a liner is very flex
10、ible, it tends to bend around the pressure pins and a shear type failure occurs rather than a straight Z-direction Z direction failure which results in lower readings. For further information on this phenomena, see sections 11.6.1 through 11.6.4. 3. Apparatus 3.1 Pin-adhesion attachment1, consisting
11、 of pins of the proper diameter and length. The requirement is seven support pins, 76.2 mm (3 in.) long 69.8 mm (2.75 in.) inside dimension when resting on supports and six pressure pins 63.5 mm (2.5 in.) 57.2 mm (2.25 in.) inside dimension when resting on supports. One end of the support and pressu
12、re pins may be attached to a separate frame which will keep the pins in each set properly spaced according to the number of 1Names of suppliers of testing equipment and materials for this method may be found on the Test Equipment Suppliers list, available as part of the CD or printed set of Standard
13、s, or on the TAPPI website general Standards page. T 821 om-12 Pin adhesion of corrugated board by selective separation / 2 flutes per unit length for the board to be tested. Means for supporting the open ends (or other end of the pins) must be provided. This other support may consist of a series of
14、 holes in a frame into which the open ends of the pins are inserted. As an alternate, notches in the end of this frame are acceptable. Base plates are required to hold the frames and pins in fixed and rigid positions. All pins, when firmly engaged in the holder, must be parallel throughout their ent
15、ire length within 0.05 mm ( 0.002 in.) to the base plate. 3.1.1 Illustrations of a commonly used instrument are shown in Figs. 1 and 2. 3.1.2 Because the radius of curvature is different for the various flute sizes, use the pin diameter as shown in Table 1. 3.1.2.1 There are no recognized flute pitc
16、h standards for corrugating rolls today. Those shown in Table 1 are still common for the designated flute profiles, but there are many others in use. There are many C flute profiles alone that require unique test fixtures. A change of as little as 3.3 flutes per meter (1 flute per foot) can cause fl
17、ank interference to the extent that tests can be affected. 3.1.2.2 When ordering test fixtures, collect several samples of combined board for the flute profile being ordered. On each sample, measure the flutes per half-meter or per foot (note the most common reading, and order the pin spacing accord
18、ingly. Samples of the board may also be sent to the test fixture manufacturer for measurement at their site. This procedure should be repeated each time corrugator rolls are changed 3.1.3 Pins should be made from cold roll steel No. 1018 and should be checked before each test for straightness. Do no
19、t use test fixtures that have crooked or bent pins. NOTE 2 1: The dimensions shown in Table 1 apply to distance between pins in a set of support or a set of pressure pins. Dimensions will vary for other flute counts per unit length. 3.2 Compression machine see TAPPI T 808 “Flat Crush Test of Corruga
20、ted Board,” Section 3.1, or TAPPI T 825 “Flat Crush Test of Corrugated Board (Rigid Support Method),” Section 3.1. 3.3 Knife cutter, single knife device with guides, or twin-blade device with guides to cut the test pieces according to the specifications in Section 5. The knives must be sharp and arr
21、anged in the device at 90 to the specimens surface. 4. Safety Take care using the knife cutter when preparing samples or changing blades. The blades are extremely sharp. Use cut-resistant gloves when operating the cutter and when replacing blades. 5. Sampling and test specimens 5.1 From each test un
22、it of a sample obtained in accordance with TAPPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard, or Related Product,” cut a minimum of ten test specimens as follows: “A” and “C” flute board 50 mm 150 mm (2 in. 6 in.) and “B” flute 31.8 mm 100 mm (1.25 in. 4 in.) from
23、 firm, uncrushed areas of corrugated board so that the 50-mm (2-in.) or 31.8-mm (1.25-in.) direction is in the flute direction of the corrugation. There are a few small compression machines where a 150-mm (6 in.) long sample creates too tight of a fit, due to their small platen size and the workable
24、 area around the platens. In cases like this a 127-mm (5 in.) long sample with the pins properly centered seems to work better, and causes no negative effects. This does not affect the area of glue line being tested, and therefore no change in the conversion factor is needed. 5.2 Ensure that all cut
25、s are parallel or perpendicular to the corrugation. 6. Conditioning 6.1 Condition the specimens in an atmosphere in accordance with TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Board, Pulp Handsheets, and Related Products.” 6.2 For special testing, such as measuring bond str
26、ength of a water-resistant adhesive, specimens may be conditioned in a high-humidity atmosphere or immersed in water, depending on the type of test desired. 3 / Pin adhesion of corrugated board by selective separation T 821 om-12 Fig. 1. Commonly used pin-adhesion test fixture components selective s
27、eparation. Table 1. Flutes per meter (foot), pin diameters and distance between pins for commonly used flutes*. No. of Distance between Flute flutes Pin diameter, pins, center to size per meter (foot) mm (in.) center, mm (in.) A 110 3.56 0.05 18.47 0.05 33 (0.140 0.002 in.) (0.727 0.002) B 155 2.03
28、0.05 12.98 0.05 47 (0.080 0.002) (0.511 0.002) C 126 3.10 0.05 16.08 0.05 38 (0.122 0.002) (0.633 0.002) *Flutes per meter (foot) may vary with corrugator manufacturer. Thus, to make appropriate apparatus use pin diameter and tolerance for each flute size, and adjust pin spacing as required to toler
29、ances noted. T 821 om-12 Pin adhesion of corrugated board by selective separation / 4 Fig. 2. Sample setup with pin adhesion test fixture. 7. Procedure 7.1 With the designated facing to be separated face down, insert the pressure pins midway between the facing and fluted medium so as to contact only
30、 the facing to be separated when the specimen is under load. Next, insert the support pins between each of the pressure pins. Finally, complete the assembly of the test instrument and center it on the platens of the compression machine, with the designated facing for separation facing down (Fig. 2).
31、 7.2 Apply a load at a constant rate of 111 22 N (25 5 lbf) per TAPPI T 808 or 12.5 2.5 mm (0.5 0.1 in.) per minute per TAPPI T 825 with the compression machine until separation of the facing from the flute tips takes place. Separation of all bond lines is not necessary. 8. Report 8.1 Report the fol
32、lowing: 8.1.1 Average force, in newtons per linear meter (pounds per linear foot) of glue line, to the nearest whole Newton (nearest whole pound) for separation. All normal A, C, and B-flute fixtures have seven support pins and six pressure pins. With these fixtures, divide the A or C-flute pin resu
33、lts by 2 and divide the B-flute by 1.25 to obtain pounds per linear foot of glue line. The sample sizes recommended in section 5.1 must be used in order for these conversion factors to be accurate. 8.1.2 The compression machine used as specified in TAPPI T 808 or TAPPI T 825. 8.1.3 The percent and n
34、ature of fiber failure. 8.1.4 The standard deviation. 8.1.5 The number of specimens tested and the side tested. 8.1.6 Any observations which may assist in interpreting the results. 8.1.7 Test conditions, if other than standard. 9. Precision 9.1 Repeatability (within a laboratory) = 5.1%, 10 specimen
35、s/average. 9.2 Reproducibility (between laboratories) = 11.8%, 10 specimens/average. 9.3 Comparability (between materials) = not known. 5 / Pin adhesion of corrugated board by selective separation T 821 om-12 9.4 These data were obtained in a round robin among 11 laboratories, testing the outside fa
36、cing of 200-pound test C-flute board. 9.5 Variability in these statements might be found for different grades of board, between inside and outside facings and different flute sizes. 10. Keywords Pin adhesion tests, Corrugated boards, Adhesion, Bond strength, Corrugating medium, Separation 11. Additi
37、onal Information 11.1 Effective date of issue: April 24, 2012. 11.2 Primary changes to the standard in the 2012 edition include additional information in Section 3 about the proliferation of flute profiles and flute spacing since this standard was written, along with recommendations on how to ensure
38、 correct manufacturing of new fixtures when ordering; inclusion of a description for a knife cutter for sample preparation in Section 3; inclusion of Section 4, Safety. 11.3 Low test results, when accompanied by a high percent of fiber separation, do not necessarily mean poor bond strength. This con
39、dition reflects the inner strength of the paper fibers under test. 11.4 A good pin adhesion test can be misleading if, for example, there is uncooked starch in the glue line. Under stress and/or abuse the glue can crack and fail, thus reducing box performance. 11.5 Related methods: APPITA P 430 “Lin
40、er Adhesion of Corrugated Board (Force Applied to Both Facings to Rupture the Weaker Bond),” Technical Association of the Australian and New Zealand Pulp and Paper Industry, Parkville, Australia; FEFCO No. 11, European Federation of Corrugated Board Manufacturers. 11.6 Light weight liners. 11.6.1 A
41、defect exists in the pin adhesion test which can result in lower values, especially with lightweight liners. Lightweight liners are more flexible and tend to bend around the pressure pins during testing. If the liner distorts too much, the adhesive bond undergoes more of a shear type separation inst
42、ead of the straight Z-direction pull which the test was designed to provide. When this happens, the results can be significantly lower. 11.6.2 Tests conducted by TAPPIs Corrugated Board Technical Service Committee show that shear separation lowers pin-adhesion results In these tests, half of the sam
43、ples from 33-26-33 C-flute trial were reinforced on both sides with 90-lb kraft liner using double coated pressure sensitive tape and the remaining half were left untouched. The pin-adhesion results showed a 29% loss in the unreinforced samples despite the fact that the liners laminated to the outsi
44、de area should have had no effect on the actual bond itself. 11.6.3 These first tests were performed using the weak-side pin-adhesion method (the non-selective method), which is more vulnerable to shearing action since both the SF and DB liners are being misshapen at the same time. Subsequent tests
45、using the selective-side test method confirm that this method is less sensitive to shearing failure on lightweight liners as the maximum loss using this method was found to be approximately 15%. It should be noted that these conclusions are based upon a very limited number of trials. 11.6.4 A number
46、 of experiments to redesign the pin-adhesion holder by either squaring the pins or coming up with some easy way to clamp a thin metal plate to the selective side being tested have not proven to be workable. To date, the only solution is to reinforce lightweight samples with heavier liner using doubl
47、e-coated adhesive tape. If the results are suspiciously low, also remember that the weak-side failure (non-selective) method appears to be almost twice as sensitive to this weakness than the selective-side method. It was also found that when by using the selective-side method the majority of combined board samples having liner weights of 42 lbs. and higher were not susceptible to a shearing loss. Your comments and suggestions on this procedure are earnestly requested and should be sent to the TAPPI Standards Department. g
