1、Designation: D4942 11Standard Test Methods forWater Pickup of Lithographic Printing Inks and Vehicles in aLaboratory Mixer1This standard is issued under the fixed designation D4942; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover two procedures for determin-ing the amount of water picked up by lithographic pri
3、nting inksin a laboratory mixer.1.2 Test Method A covers single-point water pickup; TestMethod B covers the rate of water pickup. Both test methodsare applicable to any printing ink and vehicle intended for thelithographic printing process.1.3 The values stated in SI units are to be regarded asstand
4、ard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the appli
5、ca-bility of regulatory limitations prior to use.2. Summary of Test Methods2.1 These test methods utilize a laboratory mixer for beatingwater or other agreed upon fluid into the test ink.2.2 For single-point water pickup (Test Method A), 50 mLof water is normally added to 50 g of ink and mixed in fo
6、r 5min. The water picked up is determined from volumetricmeasurements of free water.2.3 For rate of water pickup (Test Method B), water is addedto 50 g of ink in increments of 20 mL and mixed in for 1 minor more over a cumulative time period totaling 10 min. Thewater taken up by the ink after each m
7、ixing interval isdetermined gravimetrically.3. Significance and Use3.1 The lithographic printing process requires that somedampening solution be emulsified into the ink. These testmethods provide a rapid means for determining water pickupunder laboratory conditions. Test results may be useful forspe
8、cification acceptance between the supplier and the cus-tomer.3.2 In order that results be comparable, the tests must be runat the same temperature and with the same type and quantity ofliquid added prior to mixing.3.3 The emulsions obtained in these test methods are oflarger particle size than those
9、 typically produced in printingnips. Because of these and other variables in the printingprocess, water pickup results do not by themselves predictlithographic printing performance.4. Apparatus4.1 Laboratory Mixer, equipped with a stainless steel speci-men bowl 83 mm wide and 88 mm high, mixer blade
10、s thatrotate at 90 r/min, and a timing device.4.2 Balance, accurate to 0.1 g, 600-g capacity.4.3 Palette knives, two.4.4 Thermometer, quick response.4.5 pH Meter (optional).4.6 Conductivity Meter (optional).4.7 Graduated Cylinder, 50 or 100-mL.5. Reagents and Materials5.1 WaterDeionized or distilled
11、 water, preferably havinga pH of 5.0 to 7.0 (100 to 200 mL per sample); alternatively,fountain solution or other aqueous medium as agreed uponbetween the supplier and the customer may be used.5.2 Cleanup MaterialsNaptha and rags or tissues.6. Test Specimen6.1 A minimum of 100 g is sufficient for two
12、 determina-tions. Before removing ink from the can, stir or otherwiseensure that the ink specimen is representative. Close the canand replace sealing tape immediately after each ink removal.7. Conditioning7.1 Condition the instrument, water, and ink samples in aconstant temperature room or bath, pre
13、ferably at 23 6 1C.7.2 Prior to use, check the alignment of the mixer blades.With the power switch of the mixer in the off position, set theclean bowl into the turntable and engage the locking pin firmlyinto the slot in the side of the turntable. Tilt the mixer headback and insert the blades, marked
14、 left and right, into theirrespective holders. Lower the mixer head. If the blades hit the1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.56 on Printing Inks.Current ed
15、ition approved June 1, 2011. Published June 2011. Originallyapproved in 1989. Last previous edition approved in 2006 as D4942 - 89 (2006).DOI: 10.1520/D4942-11.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
16、nshohocken, PA 19428-2959, United States.side or bottom of the bowl, return the instrument to themanufacturer for realignment.8. Test Method ASingle Point Water Pickup (byVolumetry)8.1 Program the counter of the mixer for 5 min mixing time(450 revolutions).8.2 OptionalIf the first run of the day, po
17、ur test water intoa beaker. Measure pH, conductivity, and temperature at thebeginning of testing.8.3 Weigh or tare the clean dry mixing bowl. Add 50 6 0.1g of the ink to the center of the bowl.8.4 Pour 50 mL of water (from 8.2) into a graduatedcylinder. If the ink is expected to pick up more than 10
18、0 %water, use 100 mL of water. Adjust the volume to 60.5 mL.Add the entire contents to the bowl.8.5 With the mixer head tilted back insert the clean blades,marked left and right, into their respective holders. Lock thebowl on the turntable. Lower the mixer head. Press the counterreset button, making
19、 sure that 450 is displayed on the face ofthe counter.8.6 Turn the mixer on. Examine contents of the bowl asmixing progresses. If 50 mL of water had been added and allof it disappears into the ink, stop, discard the ink in the bowl,clean up, and start over from 8.3, adding 100 mL of water in8.4. The
20、 latter quantity must also be used for all other inks inthe series under study.NOTE 1With some inks, water pickup is affected by the amount ofwater added prior to mixing. When 50 mL is insufficient, do not simplyadd another 50 mL during the run, as test results may differ significantlyfrom those obt
21、ained by adding 100 mL at the outset.8.7 When the mixer stops, turn the power switch off. Tilt thehead out of the ink, detach the mixing blades, and add to thebowl.8.8 Remove the bowl from the turntable and, holding theblades at the side of the bowl, decant the free water into agraduated cylinder. R
22、un the blades very slowly through the inkin the bowl. Decant additional free water into the cylinder.NOTE 2Do not knock the bowl to force free water from the surface.Always handle the bowl gently to avoid breaking the emulsion.8.9 Record the returned water level to 0.5 mL.8.10 OptionalMeasure the te
23、mperature, pH, and conduc-tivity of the returned water. Note the appearance of the waterand the consistency of the ink and the appearance of thereturned water.8.11 Discard ink left in the bowl. Clean the bowl and themixer blades with tissue wetted with naphtha. Discard thereturned water and rinse th
24、e cylinder clean.8.12 Repeat 8.3 through 8.10 with a second specimen of thesame ink.9. Test Method BRate of Water Pickup (byGravimetry)9.1 Program the counter for the first interval of the mixingcycle.NOTE 3A commonly used cycle is 1-min intervals (90 revolutions)times ten determinations. Intervals
25、need not be uniform, for example, 1, 2,3, 5, and 10 min (90 times 3 plus 180 plus 450 revolutions).9.2 OptionalMeasure water properties in accordance with8.2.9.3 Weigh or tare the clean dry mixing bowl and blades onthe balance. Add 50 6 0.1 g of ink to the center of the bowl.9.4 Lock the bowl on the
26、 platform of the mixer. With themixer head raised, carefully insert the blades into their respec-tive holders. If ink on one blade touches the upper parts of theother blade or the side of the bowl, carefully remove the inkwith two palette knives and transfer to the bottom of the bowl.Lower the mixer
27、 head.9.5 Pour 100 mL of water (from 8.2) into a beaker. Meterout 20 mL and add to the bowl.9.6 Press the counter reset button, making sure that thedesired number of revolutions is displayed on the face of thecounter. Turn the mixer on. Examine the contents of the bowlas mixing progresses. If all li
28、quid disappears into the ink, addmore as needed to maintain a layer of excess water on thesurface of the ink.NOTE 4Few specimens will take up more than 20 mL of water withina 1-min mixing interval. If a high-water pickup specimen is being run andthe mixing interval is longer than 1 min, another 20 m
29、L should be addedprior to each subsequent minute of mixing time.9.7 When the mixer stops, turn the power switch off. Detachthe mixing blades and add to the bowl.9.8 Remove the bowl from the turntable and, holding theblades at the side of the bowl, decant the free water into thebeaker containing the
30、unused water. Run the blades very slowlythrough the ink in the bowl. Decant additional free water intothe beaker (see Note 2).9.9 Weigh the mixing bowl and contents, including theblades.9.10 Using a palette knife, transfer the ink from the walls tothe center of the bowl. Return the bowl to the mixer
31、. Replacethe blades as in 8.4.9.11 For the next mixing interval, swirl the beaker in orderto mix the returned and unused water. Meter out 20 mL and addto the bowl. Press the counter reset (or change the counter) andturn the power on. Add more water if needed to maintain anexcess layer (see Note 4).9
32、.12 When the mixer stops, repeat 9.7 through 9.11 until thecumulative mixing time totals at least 10 min.9.13 OptionalAt the end of the run, make measurementsin accordance with 8.10.9.14 Discard the ink left in the bowl. Clean the bowl and themixer blades with tissue wetted with naphtha. Discard ret
33、urnedwater and rinse the beaker clean.9.15 Repeat 9.3 through 9.14 with another specimen of thesame ink.10. Calculation10.1 Calculate water pickup, P, as follows:10.1.1 Test Method AVolumetric:P 5 V12 V2! 3 2 (1)where:D4942 112P = water pickup, % or mL water/100 g ink,V1= volume of water added, mL,
34、andV2= volume of returned water, mL.10.1.2 Test Method BGravimetric:P 5 W 2 S! 3 2 (2)where:P = water pickup, % or g water/100 g ink,W = weight of the specimen plus water picked up after eachmixing interval, g, andS = weight of initial specimen, g.NOTE 5The conversion from water pickup of the ink to
35、 water content,C, of the emulsion is C = P/(100 + P). Units are percent or grams of waterper 100 grams of emulsion.11. Report11.1 Report the following information:11.1.1 The percent water pickup to the nearest wholenumber as the mean of the two determinations, the cumulativemixing time, and a descri
36、ption of the water used for testing (forexample, tap water, deionized water, or type of fountainsolution).11.1.2 If rate of water pickup was determined, plot thepercent of water pickup versus the cumulative mixing time.11.1.3 OptionalThe mean temperature, changes in pH,conductivity, appearance of th
37、e water, and the change inconsistency of the ink.12. Precision and Bias12.1 Precision:12.1.1 Test Method AAn interlaboratory study of single-point water pickup by Test Method A was conducted in whichone operator in each of eleven laboratories tested in duplicateon each of two days three lithographic
38、 printing inks ranging in5-min water pickup from 50 to 65 %. One company was foundto be an outlier and was deleted from the analysis. The withinlaboratory pooled standard deviation was found to be 1.58 %absolute (millilitre of water per 100 grams of ink) at 9 degreesof freedom (df), and the between
39、laboratories pooled standarddeviation was 7.1 % absolute at 30 df. Based on these standarddeviations, the following criteria should be used for judging theacceptability of results at the 95 % confidence level:12.1.1.1 RepeatabilityTwo results, each the mean of tworuns obtained by one operator, shoul
40、d be considered suspect ifthey differ by more than 4.5 % absolute.12.1.1.2 ReproducibilityTwo results, each the mean oftwo runs obtained by operators in different laboratories, shouldbe considered suspect if they differ by more than 20 %absolute.12.1.2 Test Method BIn an interlaboratory study of rat
41、e ofwater pickup by Test Method B, water pickup values at 212 ,5,712 and 10 min were determined twice on one day by oneoperator in each of nine laboratories on six inks. The inksranged in water pickup from 40 to 52 % at 212 min and from65 to 100 % at 10 min. After rejecting 12 out of 156 replicatedt
42、est values as outliers, the within laboratory pooled standarddeviation was found to be 1.58 % absolute (grams of water per100 grams ink) with 97 df and the between laboratory standarddeviation 3.73 % absolute with 86 df. Based on these standarddeviations, the following criteria should be used for ju
43、dging theacceptability of results at the 95 % confidence level:12.1.2.1 RepeatabilityRepeatability cannot be determinedas both runs were conducted on the same day.12.1.2.2 ReproducibilityTwo water pickup curves, eachthe mean of two runs, obtained by operators in differentlaboratories should be consi
44、dered suspect if they differ by morethan 10.5 % absolute.12.2 BiasBias cannot be determined because there are nostandard materials. The poorer interlaboratory precision of TestMethod A compared to Test Method B is believed to be causedby the fact that the gross quantity of water added at one timeis
45、picked up as large globules which make it difficult fordifferent operators to release free water in the same manner.13. Keywords13.1 emulsification; fountain solution; inks; lithographicprinting inks; mixers; printing inks; vehicles; water content;water pickupSUMMARY OF CHANGESCommittee D01 has iden
46、tified the location of selected changes to this standard since the last issue(D4942 - 89 (2006) that may impact the use of this standard. (Approved June 1, 2011.)(1) Removal of references to a specific source of apparatussupply in 4.1.(2) Summary of Changes added.D4942 113ASTM International takes no
47、 position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own respons
48、ibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed t
49、o ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the a
