1、 TAPPI/ANSI T 835 om-14 OFFICIAL TEST METHOD 1994 REVISED 2003 REVISED 2008 REVISED 2014 2014 TAPPI Approved by the Standard Specific Interest Group for this Test Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of
2、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 method, and for ensuring that suitable safety practices have not changed s
3、ince 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 Safety Data Sheets which must be developed by all manufacturers and importers
4、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 potentially hazardous and, if so, must follow strictly the procedures specifie
5、d by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal of these chemicals. Water absorption of corrugating medium: water drop absorption test 1. Scope and summary 1.1 The water absorptivity of corrugating medium is measured by dropping a drop of water
6、on the surface of a specimen and determining the time in seconds for the drop to be completely absorbed as evidenced by the loss of sheen. 1.2 This method is applicable to corrugating medium as it is commercially produced by all processes. It is generally applicable to relatively unsized (water leaf
7、) containerboards. It may not be applicable to more highly sized boards or to grades produced in different grammage (basis weight) than those normally used in corrugating medium. 1.3 The precision and repeatability of test results are dependant on the grade and manufacturing process. Use caution whe
8、n making comparisons between samples that differ significantly in basis weights or manufacturing process. 1.4 Aging effects on the absorptivity of corrugating medium made of recycled fibers have been shown to be negligible. However, this is not true for medium with virgin fibers. See Appendix A. 1.5
9、 Due in part to the uniqueness of medium, various alternate methods are available for evaluating water absorption. These alternate methods are cited in Section 9 Additional Information. 2. Significance Some producers test absorptivity of corrugating medium to know that it has the proper receptivity
10、to the corrugating adhesive, which is an aqueous suspension of starch, for proper adhesion in the corrugating process. The absorptivity may also relate to the way the medium can be steamed by the showers on the singlefacer and by the preconditioner. 3. Apparatus and materials 3.1 Burette, syringe or
11、 dropper, which will deliver 20 1 drops/cm3of distilled or deionized water. 3.2 Rack or ring stand, to support test specimen. 3.3 Distilled water or deionized water, pH 6.5 to 7.5, 23.0 1.0C (73.4 1.8F). 3.4 Stopwatch or timer. T 835 om-14 Water absorption of corrugating medium: / 2 water drop absor
12、ption test 4. Sampling and test specimens 4.1 Select sample according to TAPPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard, or Related Product.” 4.2 Precondition and condition according to TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Board
13、, Pulp Handsheets, and Related Products.” Conduct test in atmosphere corresponding to TAPPI T 402. 4.3 From each test unit of the sample, select at least four specimens. Cut test specimens into a square large enough to perform 5 replicates per specimen without absorbed drops touching when they are a
14、pplied on each corner and in the center of the specimen. This may require some trial drops to determine the size of the absorbed drop. 4.4 Determine the felt and wire side of each specimen. If desirable, make a small mark identifying the wire side. 5. Procedure 5.1 Place the flat specimen on a rack
15、or ring, wire side down, so that its testing area is not in contact with a solid surface. 5.2 Position the burette or dropper 25 mm (approximately 1 inch.) above the top surface of the specimen. 5.3 Check the pH of the water to be used, especially if it has been in an unsealed container or not prope
16、rly nitrogen-capped. If the pH does not fall in the appropriate range; add a buffer to correct it. 5.4 Fill the burette, syringe or dropper with distilled or deionized water. 5.5 Drop a drop of water on the upper surface in the center of the specimen and immediately start the stopwatch or timer. 5.6
17、 Record the time in seconds for the drop to be absorbed into the specimen as noted by the visual observation of the gloss disappearing from the surface. Repeat on another specimen with felt side up. Repeat on the remaining two specimens with the wire side up. 5.7 Repeat the test on each corner of th
18、e specimen. Repeat with the felt side up on the second specimen. Repeat on the two remaining specimens with the wire sides up. 5.8 When making multiple tests, check the pH of the water periodically to assure it does not drift outside the acceptable range. 6. Report For each test unit, report as the
19、test result the average time for complete absorption of the drop into the surface for the ten felt-side tests and for the ten wire-side tests. 7. Precision 7.1 The precision of this method was determined in 1991 by a round-robin evaluation of this and several other methods by eight laboratories on s
20、amples of corrugating medium from eight different mills made by a variety of processes with a wide range of absorptivity levels. Tests were made both before and after aging. 7.2 The following estimates of precision are based on these results. 7.2.1 Repeatability = 13% of average according to definit
21、ions of TAPPI T 1200 “Interlaboratory Evaluation of Test Methods to Determine TAPPI Repeatability and Reproducibility.” 7.2.2 Reproducibility = 75% of average, computed from the Coefficient of Variation, as described in TAPPI T 1200 “Interlaboratory Evaluation of Test Methods to Determine TAPPI Repe
22、atability and Reproducibility.” 8. Keywords Corrugating medium, Absorptivity, Water absorption, Water drop tests 3 / Water absorption of corrugating medium: T 835 om-14 water drop absorption test 9. Additional information 9.1 Effective date of issue: November 4, 2014. 9.2 The 2014 revision includes
23、procedures to ensure the proper pH of the water used and to specify the number of tests made, and some editorial changes. 9.3 Three alternate methods which can be performed in the same general time period with equal repeatability are described below. They do not give the same numerical results, but,
24、 in general, will rank the materials in the same order as this method. 9.3.1 TAPPI T 831 “Water Absorption of Corrugating Medium: Water Drop Penetration Test.” 9.3.2 TAPPI T 819 “Water Absorption of Corrugating Medium: Boat Method,” which is now a Classical Method. 9.3.3 TAPPI T 832 “Water Absorptio
25、n of Corrugating Medium: Float Curl Method.” A. Appendix Artificial aging A.1 The absorptivity of corrugating medium made of virgin fibers has been known to change markedly, usually decreasing (an increase in absorption time) with aging. Often this change will be greatest during the first day or day
26、s after manufacture. Therefore, to compensate for those expected changes, many mills induce artificial aging as part of their off-machine control testing of absorptivity. Usually exposure to some form of elevated temperature constitutes the artificial aging process. A.2 Some possible conditions are:
27、 1/2, 2, or 7 h at 105C (221F); 15 min at 190C (374F) (this is designed strictly for an off-machine test at the time of manufacture). A.3 One laboratory found that 2-8 h at 105C (221F) gave aging equivalent to one month under natural conditions. A.4 There is good indication that the aging effect is
28、due to oxidation. One laboratory reported that samples from the outside layers of a roll had increased in absorption time 25-fold, while the inner layers were unchanged in a 10-month storage. A.5 One laboratory found a close relationship of aging with the amount of alcohol benzene extractives in the
29、 medium. If these materials are as described in TAPPI T 204 “Solvent Extractives of Wood and Pulp,” aging could indeed be an oxidation, a chemical reaction. Using the general rule of thumb for acceleration of a chemical reaction, the aging time could be halved by increasing the temperature by 10C (5
30、0F). A.6 A 1991 study by the Institute of Paper Science and Technology on complete absorption water drop aging, found an average aging increase of 600% (from 15 to 90 seconds) when 7 different mediums were retested after 2 months of aging, in roll form. The retests were made from samples taken 2 in.
31、 down inside the roll. The same study showed an average increase of 1200% (180 seconds) when after 4 months, the rolls were cut down another 2 in., and retested. The seven different mediums were selected to represent the wide variety of mediums commercially available, including recycled. A.7 Other w
32、ater absorptivity tests also showed increases in water resistance with aging; however, they were not as sensitive to aging as the complete absorption water drop test. For example, using the same seven mediums, the study showed that the percentage increases for the boat float method were 475% after 2
33、 months and 1025% after 4 months. The float curl was even less sensitive, with increases of 333% and 933% after 2 and 4 months of aging. The water strike through test was the least sensitive of all, with increases of 400% and 600% after 2 and 4 months of aging, Your comments and suggestions on this procedure are earnestly requested and should be sent to the TAPPI Standards Department.
