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AATCC Test Method 115-2000 Electrostatic Clinging of Fabrics

來源：印染在線　發布時間：2009年09月02日

Developed in 1965 by AATCC Committee RA32; revised 1969, 1973, 2000; editorially revised 1974, 1976, 1977, 1978, 1991, 1999; reaffirmed 1977, 1980, 1989; editorially revised and reaffirmed 1986, 1995.

1. Purpose and Scope This test method evaluates the relative clinging tendency of certain fabrics due to electrostatic charge generation. The test integrates the effect of fabric weight, stiffness, construction, surface character, finish application and other fabric parameters which affect the tendency of fabrics. To cling.

2. Principle Clinging of positively or negatively charged fabrics to the human body occurs due to instantaneous induction of an equal and opposite charge on the surface of the body when the charged fabric is brought close to it. A basic law of physics states that oppositely

charged materials attract each other. A metal plate exhibits a similar phenomenon of instantaneous charge induction as would the human body when placed in the field of a charged material. Therefore, a metal plate can be used to simulate the problems of clinging observed between charged garments and the human body. Some individuals are more prone to electrostatic clinging than others, and a given individual may be more prone at one time than at another time. Therefore, fabric-to-body clinging for different individuals. In this test method, the time (td) is measured for the charge on a fabric specimen to decay to a level where the electrical attractive forces between the specimen and the metal plate are overbalanced by the gravitational forces of the specimen acting to pull the specimen away

from the plate (see 12.6).

3. Terminology electrostatic clinging, n.: adherence of one substance to another caused by an electrical charge on one or both surfaces.

4. Safety PrecautionsNOTE: These safety precautions are for information purpose only. The precautions are ancillary to the testing procedures and are not intended to be all inclusive. It is the user’s responsibility to use safe and proper techniques in handling materials in this test method. Manufacturers MUST be consulted for specific details such as material safety data sheets and other manufacturer’s recommendations. All OSHA standards and rules must also be consulted and followed. Good laboratory practices should be followed. Wear safety glasses in all laboratory areas. The radioactive bar emits alpha radiation wh

ich is externally harmless to the human body. The radioactive isotope polonium 210 is toxic and precaution should be exercised to prevent ingestion or inhalation of the solid material. Do not take the radioactive bar apart or touch the radioactive strip under the grid. If the strip is touched or handled, wash hands thoroughly at once. Return the device to the manufacturer when it loses its effectiveness as a static eliminator for reactivation when tested in accordance with 12.3.1 or for disposal if use is to be discontinued. Do not discard as scrap.

5. Uses and Limitations This test method is not intended for use in determining the suitability of fabric for use in hazardous areas where the electrostatic generation of sparks might result in fires or explosions. Certain fabrics, particularly

those of heavy construction, which do not exhibit a clinging propensity by this method might cling under some conditions of use. This test method is primarily useful for determining clinging properties of lightweight apparel fabrics, such as those intended for use in lingerie.

6. Apparatus and Materials Test PLATES. Standard Test Plate__ A test plate (see 12.2) is made by bending 100×450 mm strips of 18 gauge Type 304 stainless steel across the width 150 mm from one end so that an included angle of 1.22±0.04 RAD is formed between the 100×150 mm base and the 100×300 upright plate. The grain of the finish should be such that the 450 direction of the test plate corresponds to the length or grain direction of the stainless steel sheets from which they are made. The face

of the 100×300 plate must have a No.4 finish(see 12.2.1) on the included angle side, and should be kept clean and smooth at all times. A fine line is indented across the test plate surface 230 mm from the top of the plate and this is used to position the lower edge of the specimen(see 12.2). Variable Angle Experimental Test Plate __ The sensitivity of this test depends on the included angle of the metal plate and can be diminished by decreasing the included angle or vice versa. A more versatile version of the test plate, suitable for research work, which allows facile change of the sensitivity, uses a 25×100×100 mm aluminum base with several slots machined into the base at different angles (e.g., 0.017, 0.087, 0.175, 0.35, 0.52, 0.70, 0.87, 1.05 RAD) from the vertical ax

is into which a 100×360 mm stainless steel plate fits(see 12.4). Grounding Plate__ This is a 200×360 mm, flat, 18 gauge Type 304 stainless steel plate, attached to a ground, such as a water pipe, with wire (e.g., No. 18 stranded, plastic-covered electronic wire). One such grounding plate is required for each test plate. Radioactive bar (see 12.3). Rubbing blocks, white pine, approx. 20×50×150 mm adjusted to weigh 65 g and with strips of 20 mm wide, double-faced tape on the ends of each block to attach ends of the rubbing fabric. Polyurethane foam, 25×100×300 mm non-rigid, having a density of 21 kg/m3 and an ILD (Identification Load Deflection) firmness of 6.8 kg when tested (see 12.2 and 12.10) as directed in ASTM Method D3574. Clamps, metal (e.g., No.3

Bulldog Clamp or Di-acro Toggle Clamp, see 12.4), with 70 mm edges covered with 20 mm electrical tape to prevent scratching of the surface of the test plates. Stopwatch, with 0.01 min or one of equivalent precision marked in other units. Forceps or tweezers, non-conducting, ivory-tipped, forceps used with analytical balances. Oven, forced-draft type, capable of maintaining a temperature of 105±2℃. Conditioning chamber, capable of providing relative humidity control of 40±2% and temperature at 24±1℃, the conditioning test chamber should be capable of providing the necessary range of test conditions (such as 20-65±2% RH and from 10-30±1℃). Rubbing fabrics. Nylon rubbing fabric__ 100% spun nylon 6, 6(Style No.361)(see 12.5). Polyester rubbing fabric__ 100% s

pun polyester (Style No.777)(see 12.5). Fabric iron, domestic hand type, with appropriate settings (see Table I). Cleaning solvent: halogenated hydrocarbon metal-cleaning solvent, such as DuPont’s Vertrel MCA or Vertrel X-P10, hereinafter called HH Solvent (see 12.1).

7. Test and Rubbing Specimens Test fabrics__ Twelve 75×230 mm test specimens are required. Using die or scissors, cut six specimens with the longer dimension parallel to the warp, or wale, direction and six with the longer dimension parallel to the fill, or course, direction. (Do not cut fabric specimens with a hot soldering iron or heated wire since the edges can cause localized static problems due to heat degradation of the fibers and antistatic agents.) Rubbing fabrics__ Both nylon and polyester rubbing fabrics

are required. Using die or scissors, cut six nylon and six polyester rubbing fabrics, each 75×230 mm, with the longer dimension parallel to the warp, or wale, direction of the fabric. Do not contaminate the test specimens or the rubbing fabric by unnecessary handling or by allowing them to come in contact with transferable materials. If either the test or rubbing fabric specimens do not lay completely flat, press them free of creases or wrinkles with a dry, clean iron at the appropriate setting as directed in Table I. Do not use test specimens with curled edges.

8. Conditioning Since equilibration of a test specimen from the dry versus the wet condition relative to the humidity of the test chamber may show hysteresis, precondition the specimens from the dry side relative to the humidi

ty in the test chamber. To accomplish this, place the test and rubbing specimens in the forced-draft oven at 105±2℃ for 30 min. Transfer them immediately to the controlled humidity chamber allowing no more than 15 s for the transfer. Condition and test the test and rubbing specimens at 40±2%RH and 24±1℃ in the controlled humidity chamber for at least 16 h. if the test is conducted at lower humidities (such as 30±2% or at 20±2%), or at higher humidities (such as 65±2%), keep the temperature at 24±1℃ for standard testing. If other temperature conditions are used for nonstandard testing, state the temperatures used in the report. For any humidity or temperature test conditions that are to be used, the test and rubbing specimens should be condit

ioned for at least 16 h(see 12.11).

9. Procedure Clean the metal test plate before testing every different lot of fabric. To clean, swab with a facial tissue saturated with HH Solvent (wear protective gloves). Allow the plate to dry at least 5 min in the conditioning test chamber as a result of cleaning the metal test plate. If the No.4 finish on the surface of the test plate is changed noticeably due to use, replace the test plate with a new one. Handle the fabric test specimens and rubbing fabrics at only one marked corner to minimize transfer of impurities to the remainder of the fabric. Adhere double-faced adhesive tape around all four 20 mm thick sides of the rubbing block. Completely discharge the rubbing fabric on both sides with the radioactive bar (Caution, see 4.2). Place a 50&tim

es;150 mm side of wood block on the rubbing fabric in such a way that the 150 mm dimension of the block parallels the 230 mm dimension of the rubbing fabric and the block is centered on the fabric. Bring up the protruding edges of the fabric so that they adhere tightly to the double-faced tape on all four sides of the rubbing block. Take care that the double-faced tape does not extend to the area between the rubbing surface of fabric and the block. Grasp a test specimen at one corner and allow it to hang free. Discharge both sides of the test specimen using the radioactive bar, holding the bar not over 25 mm away from the fabric as it moves up or down (Caution, see Section 4 and Fig.1, Step A). Fasten the test specimen at the top of the long arm of the metal plate on the 1.22 RAD included

angle side with a metal bulldog or toggle clamp with the face of the test specimen out. Position the lower edge of the test specimen even with the indented line on the metal plate. Attach the metal grounding plate with the wire to a suitable ground and place it horizontally in the controlled humidity chamber and lay the polyurethane foam on top. Place the metal test plate with attached test specimen in a horizontal position on the polyurethane foam in such a way that the long arm of the plate completely rests on the polyurethane foam with the short arm of the test plate closest to the operator and pointing upward. The clamp should extend over the edge of the supporting foam so that the back of the plate is completely supported. Place the rubbing block with attached rubbing fabric at the to

p of the plate so that the long axis of the test specimen are at right angles (see Fig.1, Step B). The side of the rubbing block that does not expose the cut edge of the rubbing fabric should be down. Keep the test plate and rubbing block perfectly flat on their facing surfaces to ensure complete contact between test and rubbing fabrics during charge generation. Place the middle fingers on the back edge of the rubbing block and pull the rubbing assembly the full length of the test specimen (see Fig.1, Step C).Grasp the lock between the thumbs and middle fingers at the ends of the block, lift the assembly from the test specimen and return the rubbing assembly to its original position at the top of the test specimen. Repeat this rubbing sequence 12 times at a cycle of approx. 1 rubbing cycle

per second. The total 12 rubbing cycles should be completed in no more than 15 s. for constant rubbing pressure, take care that the only downward pressure on the test specimen comes from theweight of the rubbing block and fabric. Quickly place the assembly in an upright position on a grounded plate Grasp the lower right corner of the test specimen with the nonconducting tweezers(see Fig.1, Step D), pull the unclamped part of the test specimen completely away from the metal plate to a point where the test specimen is positioned vertically for ±0.5 s (see Fig.1, Step E), and then release the test specimen from the tweezers. Start the stopwatch immediately(see Fig.1 Step F). After every 30±2s, grasp the lower corner of the test specimen with nonconducting tweezers, pull the tes

t specimen completely away from the metal plate to a point where the test specimen is positioned vertically for 1±0.5s, and then release the test specimen from the tweezers. Record the time, to the nearest 0.1 min, for the fabric to decling of its own accord (see Fig.1, Step G). Disregard any tendency for the test specimen to continue clinging within 25 mm of the bottom of the holding clamp. If the time is greater than 10 min, discontinue the test and report td as > 10 min(greater than 10 min). In some cases, a different “maximum cling time” period may be chosen. In this case, report the actual maximum cling time used for the testing. If the test specimen declings almost completely but persists in clinging in a small localized area in addition to the area within 25mm

of the bottom of the holding clamp, discard and test an additional specimen. If this condition is observed in all test specimens, note and report the condition without assigning cling time. Test three specimens in both warp(or wale) and filling (or course) directions against both nylon and polyester rubbing fabrics, using fresh test specimens and fresh rubbing fabric surfaces for each determination (see 12.3).

10. Report Report the time(td) to the nearest 0.1 min required for a test specimen to decling from the metal plate as specified in 9.9 and 9.11.2. Report the three individual values of tests in both warp (or wale) and filling (or course) directions as well as an average of each of the three determinations, reporting separately the times (td) obtained with both nylon and polyester rubb

ing fabrics. If the td value of two of a set of three test specimens is less than the selected maximum cling time selected from 9.11.1 but the td value of the third test specimen is greater than the selected maximum cling time, report the average of the two determinations which are less than the selected maximum cling time and disregard the td value of the third test specimen. Report that the third specimen exceeded the maximum cling time. If the td value of two of a set of three test specimens is greater than the selected maximum cling time, report the td value as greater than the selected maximum cling time and disregard the td value of the third test specimen. Report the percent relative humidity and the temperature at which the specimens were tested.

11. Precision and Bias Precision. Ex

tensive interlaboratory evaluations run in 1995 on woven fabrics indicated that, for the fabrics tested, the 95% confidence limits of this test are ±0.5 min (see 12.6). An interlaboratory test on tricot fabrics was run in 1975 which involved the following variables:5 laboratories4 fabrics2 levels of laundering2 fabric directions2 relative humidities2 types of nylon and 2 types of polyester rubbing fabricsBased on the results of the study, the 95% confidence limits for the average decling time of a set of three observations, none of which exceeds the maximum cling time of 10 min, is ±2.0 min for tests at 20% RH and ±1.7 min for tests at 40% RH.Some of the fabrics tested did not cling at all (0 min) while others clung more than the maximum 10 min, at which point testing

is discontinues. In this interlaboratory test, 576 different test conditions were listed which involved 1728 individual decling measurements. Of the 576 test conditions, 469 contain at least one 0 or 10 cannot give a valid estimate of the experimental error( see 12.9). Bias. Electrostatic clinging can be defined only in terms of a test method. There is no independent method for determining the true value. As a means of estimating this property, the method has no known bias.

12. Notes and References HH Solvents: Vertrel® is a trademark of the DuPont Company, Wilmington, DE, and is available through their Fluoroproducts Division. Other suitable non-ozone-depleting halogenated hydrocarbon solvents and mixtures may be available from other suppliers (Freon® 113, Genetron® 113, and si

milar products previously referenced by this test method are no longer available.) Available from AATCC, P.O. Box 12215, Research Triangle Park, NC 27709; tel 919/549-8141; fax: 919/549-8933; email: orders@aatcc.org The specified No.4 finish on the standard test plate shall be as specified in the ASTM Metals Handbook, Vol.2, 8th Edition; p 599(1964) which states: Following initial grinding with coarser abrasives, sheets are finally finished with lubricated 120-150 mesh abrasive belts.” The resultant No.4finish surface roughness expressed in micro-inches is 45 maximum. The staticmaster Ionizing Unit is available from NRD, Inc., 2937 Alt Blvd. North, Grand Island NY 14072; tel: 716/773-7634. Since the polonium in this radioactive element has a limited half life (approx.6 months), the r

adioactive bar must be checked periodically to be sure that it is sufficiently active for complete removal of charge. The radioactive bar may be checked by testing a specimen known to exhibit a cling time of at least 10 min when tested as directed in Section 6. A jersey stitch nonantistatic heatset 40 denier nylon tricot fabric free of finish or scoured and in the range of 50-100 g/m2 is satisfactory for this purpose. The fabric should be charged as directed and then deionized with the radioactive bar. If the test specimen shows zero cling time, the radioactive bar is sufficiently active for complete removal of charge. Available from Carr Land Mfg. Co., 4200 Krause Ct., St. Louis MO 63119. Available from Testfabrics inc., P.O.Box26, 415 Delaware St., W.Pittston PA 18643; tel: 570/603-0432;

fax: 570/603-0433; email: testfabric@aol.com.( construction details available from AATCC, see 12.2). For details, see American Dyestuff Reporter 56, pp 345-350(1967). The clinging behavior by this method of test of clean, finish-free 100% cotton fabrics can be used as a reference point for antistatic behavior of test fabrics of similar construction and weights. Garments made from such clean, finish-free 100% cotton fabrics are generally considered to be free of clinging problems under use conditions. Some typical declinging times for 100% cotton fabrics at 17% RH and 21℃ are given in the reference cited in 12.6. S/400W, a standard bleached 80×80 cotton print cloth(available from Testfabrics Inc., see 12.5; or textile innovators Corp., see 12.10) can be used as a reference fabric in

most instances. Gayler, J., R.E. Wiggins, and J. B. Arthur, Department of Textile Technology, School of Textiles, North Carolina State University, “Static Electricity Generation, Measurement, and Its Effect on Textiles,” pp 11-12(may 1965). The statistical analyses and related data are on file at AATCC, P.O. Box 12215, Research Triangle Park, NC 27709; tel 919/549-8141; fax: 919/549-8933; email: orders@aatcc.org. Available from Textile Innovators Corp., P.O.Box 8, Windsor NC 27983; tel: 252/794-9703; fax: 252/794-9704. At a given temperature, accumulation of static electricity generally is greater the lower the relative humidity (and vice versa). For example, fabrics which show a low degree of static accumulation at 40% RH and 24℃ may exhibit severe static accumulation at 25% R

H and 24℃ while fabrics which exhibit static problems at 40% RH and 24℃ may exhibit a low degree of static accumulation at 65% RH and 24℃. The relationship between the tendency for static accumulation and relative humidity varies with the specific antistatic agent, fiber, fabric construction, surface charger, etc. Therefore, alt hough 40% RH and 24℃ are the standard conditions for the test, significant information as to the probable antistatic performance properties of a fabric may require that tests be run also at a lower relative humidity, such as 20%, and 24℃, an atmospheric condition not unusual in modern heated and air conditioned buildings. Complete evaluation may also require tests at the upper level of 65% RH and 24℃. Clinging in a small localized area can be indicative of the pres

ence of foreign material or some irregularity and may not be characteristic of the clinging properties of the fabric lot from which the test specimens were taken. Since several determinations sometimes can be run concurrently, time can be saved by having several test plates and grounding plates available.