1、Designation: F1425 06 (Reapproved 2011)Standard Test Method forDetermining the Tribocharge of Two-Component DeveloperMaterials1This standard is issued under the fixed designation F1425; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the 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. Scope1.1 This test method describes a technique for measuringthe tribocharge or charge-to-mass ratio of a sample
3、 of devel-oper material.1.2 This test method determines the concentration of tonerin a sample of developer material.2. Referenced Documents2.1 ASTM Standards:2F335 Terminology Relating to Electrostatic Imaging3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 charge to mass ratio
4、the quantity of charge per unitof mass. In xerography, the tribocharge per unit of mass of thetoner.3.1.2 tribochargethe general term for the electric chargeof a material whose charge is created by the tribo electriceffect, or the rubbing of unlike surfaces together.3.2 Terms and definitions used in
5、 this test method may befound in Terminology F335.4. Summary of Test Method4.1 Two component developer materials used in the xero-graphic process are charged by the tribo electric effect.Xerographic developers are commonly made up of two mate-rials: toner and carrier. Toners are typically under 38 m
6、 in sizewhile carriers are several times larger. This size difference isused in the measurement of tribocharge.4.2 The sample cell contains a very fine screen (400 mesh),which allows toner to pass through and blocks carrier frompassing through. The sample cell is held in an insulated blockwith an el
7、ectrical connection between the sample cell and theelectrometer. The electrometer measures the charge on the cellas the toner is blown off the carrier by a highpressure airstream. From the difference in weight of the cell before andafter the blow-off, and the electrometer charge measurement,the char
8、ge to mass ratio and percent toner concentration of thedeveloper material can be calculated.5. Significance and Use5.1 This test method measures a fundamental property of atoner and developer mix used in copiers and printers. This testmethod is used for quality control purposes and to determinethe a
9、bility of the toner and developer materials to develop ontothe photoreceptor.5.2 This test method may be used to measure the chargeto-mass ratio of new developer mixes.5.3 This test method may be used to measure the chargeto-mass ratio of developer material samples taken from a ma-chine.5.4 This tes
10、t method may be used to measure the tonerconcentration of new developer mixes.5.5 This test method may be used to measure the tonerconcentration of developer material samples taken from amachine.6. Interferences6.1 Any differences in this test method used to charge thetoner that would effect the fre
11、quency of collisions of toner andcarrier, such as rolling the container of developer material in acontainer of different size or at a different rate, may causevariation in the results.6.2 Any differences in the material that the container used toroll the developer material is made from could cause v
12、ariationsin the results.6.3 The environmental conditions (temperature, humidity)can effect the results because some toners and carriers absorbwater onto their surfaces. The water content of the compressedair can effect the results for hydroscopic materials.1This test method is under the jurisdiction
13、 ofASTM Committee F05 on BusinessImaging Products and is the direct responsibility of Subcommittee F05.04 onElectrostatic Imaging Products.Current edition approved Oct. 1, 2011. Published September 2012. Originallyapproved in 1992. Last previous edition approved in 2006 as F142506. DOI:10.1520/F1425
14、-06R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, P
15、O Box C700, West Conshohocken, PA 19428-2959. United States16.4 The 400-mesh screen of the sample cell can becomeclogged with material. This is indicated by increasing cellweights. The clogged screen may be able to be cleaned byrunning a test with the cell empty or by blowing filtered airthrough the
16、 cell from a hand-operated nozzle. If the cellweights indicate that the cell is still clogged, the cell can becleaned in an ultrasonic cleaner. Be sure the cell is rinsed anddried before use.6.5 The 400-mesh screen can develop holes or gaps afterrepeated use. This is evidenced by high percent toner
17、valuesindicating that the carrier particles have passed through the finescreen, giving lower after blow-off cell weights.7. Apparatus7.1 Sample Cell The sample cell contains a very finescreen (400 mesh) supported by a coarse screen. The finescreen allows toner to pass through and blocks carrier from
18、passing through. See Fig. 1.7.2 Tribometer, any device which provides the functions ofholding the cell in the proper electrical connection, blowing theair through the cell under controlled conditions of air pressureand time, and collecting the waste toner. See Fig. 2.7.3 Vacuum Cleaner, of a type us
19、ed in copier servicesuitable for removal of toner (fine particle filter).NOTE 1The hose should be made of material which is resistant totoner, if possible. The vacuum cleaner is used to remove the waste toner.37.4 Electrometer, capable of measuring charge in the rangefrom 108to 106C.47.5 Air Supply
20、Line, capable of supplying air at a minimumflow rate of 1.6 to 2.0 ft3/min at 100 psi. The air supplied mustbe filtered to be free of particulate matter as well as oil (mostindustrial air systems supply air which includes a minuteamount of oil used as a lubricant in air-operated equipment).A5-m pre-
21、filter and oil coalescing filter will remove particlesand oil. Either the air supply line, or the tribometer unit mustinclude an air-pressure regulator.7.6 Analytical Balance, capable of weighing the cell (ap-proximately 85 g) to 0.0001 g.7.7 Roller Unit A two-roll device where one roll ispowered by
22、 a motor. The sample container is placed on the tworollers such that when the roller is powered, the samplecontainer rolls on top of the two rollers. The roller unit shouldbe capable of rolling several sizes of containers of developer,and have a variable speed motor with enough torque to rollsamples
23、, or developer mixed of weights appropriate to theapplication. See Fig. 3.8. Sample Preparation8.1 Roll commercially prepared developer mixes or previ-ously prepared large batches for at least 30 min at theappropriate speed for the size of the container.8.2 Roll freshly made large batches for at lea
24、st 4 h at theappropriate speed for the size of the container.8.3 Prepare small carrier/toner samples (approximately 100g) in a glass jar and roll for at least1hattheappropriate speedfor the size of the container.8.4 Run samples taken from a copy machine as soon aspossible. Take the sample after the
25、machine has been turningthe developer unit for at least 10 min, so that the toner has hadan opportunity to tribocharge.8.5 All speeds are relative to the container size. The actualsurface speed of the containers in all cases is approximately 90ft/min.3The sole source of supply of the apparatus (vacu
26、um cleaner 3M Model 496 AG) known to the committee at this time is 3M, 3M Center, St. Paul, MN551441000. If you are aware of alternative suppliers, please provide this informa-tion to ASTM International Headquarters. Your comments will receive carefulconsideration at a meeting of the responsible tec
27、hnical committee,1which you mayattend.4The sole source of supply of the apparatus (Keithley 610C electrometer) knownto the committee at this time is Keithley Instruments Inc., 28775 Aurora Road,Cleveland, OH 44139. If you are aware of alternative suppliers, please provide thisinformation to ASTM Int
28、ernational Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.FIG. 1 Sample CellFIG. 2 TribometerF1425 06 (2011)29. Calibration9.1 Initially, make a series of measurements of a developermaterial to determine the samp
29、le size, air pressure, and timerequired to completely remove the toner from the carrier for thetribometer device being used. Use these standard conditions forall similar samples. For typical negative toners, a 3-g developersample requires 60 psi of air pressure for 120 s yieldingcharge-to-mass ratio
30、s of 5 to 25 C/g for 3 to 4 % tonerconcentration.9.2 On a regular basis, such as every 20 samples, or after theinstrument has not been used for more than one month, checkthe instrument by measuring the charge-to-mass ratio and tonerconcentration of a known developer mix. Any differences inthe measur
31、ements of the known developer mix could indicatethe need for maintenance.9.3 Test the fit of the new screens by performing a test withonly carrier material in the cell. The before and after cellweights should be the same if the screens have been properlyinstalled. This procedure can also be used to
32、verify that screensneed to be replaced.10. Procedure10.1 Set the electrometer controls as follows:10.1.1 Polarity, + or as required. (Meter polarity dependson material.)10.1.2 Range, from 106to 108C.10.1.3 Refer to the electrometers instruction manual fordetailed operating instructions.10.2 Install
33、the vacuum cleaner hose where appropriate toremove the waste toner.10.3 Set the pressure reducer valve so that the air pressurethrough the cell is 60 psi.10.4 Set the tribometer instrument to deliver the air for a settime period. A typical negative toner requires 120 s to removethe toner from the ca
34、rrier. The time required can be determinedby repetitive measurements of the same sample. When noadditional weight loss is detected, the time to remove all thetoner from the sample has been determined.10.5 Weigh the clean cell on an analytical balance to thenearest 0.0001 g. Record the weight under I
35、tem A on the datasheet.10.6 Add enough developer material so that the amount oftoner expected to be in the sample is large enough to beweighed accurately. Typically, approximately3gofdeveloperis added to the cell and reweighed. Record this weight underItem B on the data sheet.10.7 Assemble the cell,
36、 taking care not to lose any material.10.8 Place the cell in the cell holder and close the unit.10.9 Ready the electrometer controls.10.10 Turn on the vacuum cleaner, and then turn on the airsupply. The electrometer should show an immediate response.Turn off the air and vacuum cleaner after the appr
37、opriate timeperiod if the tribometer does not automatically shut them off.10.11 When the test is complete, record the electrometerreading on the data sheet under Item D. Note that theelectrometer measures the residual charge on the cell after thecharged toner is removed. The electrometer reading wil
38、l beopposite in sign to the charge on the toner.10.12 Open the unit, remove the cell. Do not clean off theresidual toner on the surface of the cell. Weigh the cell. Recordthis weight under Item C on the data sheet.10.13 Open the cell, empty it out, and holding both halvesso that the open ends are fa
39、cing down, bang the halves togetherto remove the last traces of material. Alternatively, blow airthrough the cell halves. The cell is clean when it weighs thesame as the empty weight (A) on the data sheet.11. Calculation11.1 Calculate the charge-to-mass ratio (Q/M) as follows:FIG. 3 Roller UnitFIG.
40、4 Sample Data SheetF1425 06 (2011)3Q/M 52D/10F 5mC/gwhere F=BC.11.2 Calculate the apparent toner concentration as follows:F/E! 3100 5 % tonerwhere E=BA.12. Interpretation of Results12.1 For any two component developer samples, the tribo-charge (charge-to-mass ratio) is created by the frictionalrubbi
41、ng of the toner and carrier surfaces. The sample prepara-tion plays an important role in the measured tribocharge value.Samples must be allowed to fully charge before the measure-ment is performed or false low values will result.Additionally,when comparing two samples, their charging history must be
42、taken into account.12.1.1 For two component developers, tribocharge is afunction of the concentration of toner in the developer sample.At very high toner concentrations, there is more toner than thesurface of the carrier can interact with. This condition leads tolower tribocharge values.12.2 The qua
43、lity of a used developer can be inferred from acomparison of the tribocharge value of the test developer andthe tribocharge value of a fresh developer at the same concen-tration.12.2.1 If both samples are similarly prepared, a lowertribocharge value could indicate that the used developerscarrier is
44、partially impacted with toner, thereby reducing thecarrier surface area that can participate in charging. A highertribocharge value, accompanied by lower print density couldindicate that the used developer is contaminated with asubstance that can effectively compete with the toner atdevelopment.12.2
45、.2 If the used developer sample was charged in adeveloper unit, and the fresh developer sample was charged byrolling, a lower tribocharge value for the used sample couldalso indicate that the developer unit does not provide adequatemixing.13. Precision and Bias13.1 Repeated measurements of the same
46、developer sample,measured over many days in one laboratory gives a standarddeviation of 0.62 C/g for a charge-to-mass ratio of 12.60C/g, and 0.35 for a percent toner of 3.48 %.14. Keywords14.1 developer; tribo; tribocharge; two componentsASTM International takes no position respecting the validity o
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