1、 TAPPI/ANSI T 845 om-14 ISSUED 2014 2014 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 connection with the use of such information or data, including but
2、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 Method TAPPI CAUTION: This Test Method may include safety precau
3、tions 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 precautions are complete and are appropriate to their use of the m
4、ethod, 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 for the handling of such substances are set forth on Material Safet
5、y 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 whether any of the chemicals to be used or disposed of are poten
6、tially 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. Wet pin adhesion of corrugated board by selective separation 1. Scope 1.1 This method measures the force
7、 required to separate the linerboard facings from the medium in corrugated board after the board has been immersed in water for a period of time. It may be used to evaluate the water resistance properties or levels in water resistant adhesive. 1.2 This procedure mirrors the process in T 821 “Pin Adh
8、esion of corrugated board by selective separation” with differences in how samples are prepared for testing and how results are interpreted. 2. Significance 2.1 The test described in this procedure measures the Z-direction force required to separate selectively either the inside or outside facing of
9、 corrugated board. 2.2 Good adhesion of the corrugated medium to its facings is important in obtaining high-quality corrugated 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 so
10、me manufacturing defects. 2.2.1 Good adhesion under wet/saturated conditions, examined in this method, may be important for boxes used under refrigerated conditions or other environments with high humidity, as well as for boxes that come in direct contact with water. 2.2.2 Some producers of corrugat
11、ed board, manufacturers of combining adhesive, and manufacturers of resin for adding water resistance to the adhesive, have definitions of the level of water resistance provided to the board that are based on the absolute wet-pin test values obtained following a given immersion time. T 845 om-14 Wet
12、 pin adhesion of corrugated board by selective separation / 2 3. Apparatus 3.1 Pin-adhesion attachment1identical to that used in T 821, consisting 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 o
13、n 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 pressure pins may be attached to a separate frame which keeps the pins in each set properly spaced according to the number of flutes per unit length for the boa
14、rd 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 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 require
15、d to hold the frames and pins in fixed and rigid positions. All pins, when firmly engaged in the holder, must be parallel throughout their entire 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 radi
16、us 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 pitch 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 ar
17、e many C flute profiles alone that require unique test fixtures. A difference between the actual flute structure and the jig of as little as 1.3 flutes per meter (0.4 flute per foot) may cause flank interference with the inserted pins to the extent that dry pin test results can be affected. This pro
18、blem is exacerbated when performing the wet pin test as the weaker bond following soaking facilitates sample failure with the slightest misalignment while inserting the pin fixture pins in the sample. Fig. 1. Commonly used pin-adhesion test fixture components selective separation. 1Names of supplier
19、s 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 Standards, or on the TAPPI website general Standards page. 3 / Wet pin adhesion of corrugated board by selective separation T 845 om-14 Fig. 2. Sample
20、 setup with pin adhesion test fixture. Table 1. Examples of 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 (0.1
21、40 0.002 in.) (0.727 0.002) B 155 2.03 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 corrugating roll, and only one representative flute count is presented here as an example for each flute size. To mak
22、e an appropriate fixture, use the pin diameter and adjust the pin spacing as required to tolerances noted. 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
23、common or average reading, and order the pin spacing accordingly. 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
24、 should be checked before each test for straightness. Do not use test fixtures that have crooked or bent pins. NOTE 1: Some laboratories are experimenting with using aluminum jigs, and are reporting some success. In some cases the pins are hardened steel but the frames are aluminum. These fixtures c
25、an be lighter weight, and may be less likely to damage the bond or the flute structure when inserted prior to testing. No comparison study between these jigs and more traditional jigs has yet been published. T 845 om-14 Wet pin adhesion of corrugated board by selective separation / 4 3.2 Compression
26、 machine see TAPPI T 822 “Ring crush of paperboard (rigid support method),” Section 4.1, 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 t
27、he specifications in Section 5. The knives must be sharp and arranged in the device at 90 to the specimens surface. 3.4 A pan, sink, or other container at least 3 in. deep that shall be filled with water and in which samples shall be completely submerged when oriented with their flute openings upwar
28、ds. 4. Safety 4.1 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 unit of a sample obtained in accordance with T
29、APPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard, or Related Product,” cut a minimum of ten test specimens for each set of glue bonds (doubleback side or singleface side) as follows: “A” and “C” flute board 50 mm 150 mm (2 in. 6 in.) and “B” flute 31.8 mm 100 mm (
30、1.25 in. 4 in.), so that the 50-mm (2-in.) or 31.8-mm (1.25-in.) direction is in the flute direction of the corrugation. 5.1.1 For doublewall board, samples should be cut to the sizes above appropriate to stress the bonds of each flute structure. For example, to test all four bonds in a CB doublewal
31、l board, one would cut two sets of samples 50 mm 150 mm (2 in. 6 in.) to use for testing of the C flute bonds and two sets of samples 31.8 mm 100 mm (1.25 in. 4 in.) to use for testing of the B flute bonds. NOTE 2: Testing doublewall samples as received increases sample rigidity and can impact pin a
32、dhesion results, usually making them higher. Another approach involves removing the liner and medium of the flute structure not under examination, either before soaking or after soaking, before testing. For example, if interested in the singleface bond of the B flute medium in CB doublewall one woul
33、d remove (typically by cutting it off) the C flute medium and associated liner, leaving a structure that appears similar to a singlewall B flute board. 5.1.2 There are a few small compression machines where a 150-mm (6 in.) long sample creates a too-tight fit, due to their small platen size and the
34、workable 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
35、 all cuts are parallel or perpendicular to the corrugation direction. 6. Conditioning 6.1 As samples are immersed in water prior to testing, typical preconditioning and conditioning in accordance with TAPPI T 402 is not required. However, if the percent strength retained is desired, precondition, co
36、ndition, and prepare a parallel set of test specimens and evaluate them following TAPPI T 821. 7. Procedure 7.1 Prepare at least 10 specimens following the process above for each set of glue lines to be evaluated. 7.2 Completely immerse the specimens in water with flute openings facing up, separated
37、 from each other so they do not stick together. Remove all air bubbles from the flutes by gently shaking the specimens when initially submerging. Soak under standard TAPPI conditions (see TAPPI T 402) to insure consistent water temperature. NOTE 3: Most labs use tap water for soaking samples. It is
38、not known if there would be any meaningful impact to test values, or reduction in between lab variability in test results, if distilled or deionized water were used. 5 / Wet pin adhesion of corrugated board by selective separation T 845 om-14 7.2.1 The time specimens remain submerged varies across t
39、he industry; the most typical soak times are 1-, 2-, and 24-hours. Different soak times saturate or stress the adhesive bond to different extents. Report the soak time with the results. 7.2.2 For some adhesive bonds, boards soaked for a short time may have higher wet-pin values than boards soaked fo
40、r 24 hours. However the level of water saturation in the boards, specifically heavier weight papers, can vary specimen to specimen with short soak times. The repeatability and reproducibility study performed in 2014 in support of this method confirmed that for some board samples one obtains statisti
41、cally different wet pin values when using different soak times, while for other board samples values can be similar. 7.3 After soaking, test the specimens immediately without letting them dry out. Analyze only the number of specimens that can be tested in a batch, staggering soak times so that their
42、 times are consistent. 7.3.1 If the plies separate during soaking, the pin value is zero; report as a complete failure of the board and lack of water resistant adhesive. 7.3.2 Take extra care when inserting pin fixtures into wet specimens so as to not separate plies or tear the medium. With the desi
43、gnated facing to be separated face down, insert the pressure pins midway between the facing and fluted medium so as to contact only 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
44、instrument and center it on the platens of the compression machine, with the designated facing for separation facing down (Fig. 2). 7.3.3 Follow the same testing procedure as used for dry pin adhesion. However, if the specimen separates while inserting pins into the fixture, make a comment indicatin
45、g failure. 7.3.4 Apply a load at a constant rate of 12.5 0.25 mm (0.50 0.01 in.) per minute until separation of the facing from the flute tips takes place. Separation of all bond lines is not necessary. Report the maximum load during this process as the wet pin adhesion strength. 7.4 Following pin t
46、esting and the removal of the pin jig, separate the facings by hand and examine the area of bond failure. Note whether there is fiber tear of the liner, medium, or both at the glue lines, and estimate how much fiber tear has occurred. The amount and location of the failure of the bond can provide ad
47、ditional useful information regarding the weakest link in the corrugated bond: if significant fiber tear is present it indicates that the wet glue lines were stronger than the paper, while little observed fiber tear implies the paper bonding was stronger than the wet adhesive. 8. Report 8.1 Report w
48、et pin values on an absolute scale and/or on a relative basis in comparison with the dry pin values: 8.1.1 Average and standard deviation of the force required for separation, in newtons per linear meter (pounds per linear foot- plf) of glue line, to the nearest tenth of a newton (nearest tenth of a
49、 pound). 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 results by 2 and divide the B-flute by 1.25 to obtain pounds per linear foot of glue line. Use the specimen sizes recommended in section 5.1 in order for these conversion factors to be accurate. 8.1.2 If dry pin values are available from T821 testing done in parallel, wet strength may be further illustrated as the percent strength retained after soaking by determining the ratio of wet pin
