006.Silicone Release Test Methods


Published on

Dear Friends here is a Presentation on the Methods employed for Testing Silicone Release Coated Liners.

Published in: Technology

006.Silicone Release Test Methods

  1. 1. ByShrikant Athavalepsatechno@gmail.com05/07/201107-05-2013 1
  2. 2. Off Machine TestsOff Machine TestsOff Machine Test• Curing rate - Smear test with finger- Loop test with Tesa 4154- Subsequent adhesion (SA),- Quick subsequent adhesion(QSA) FTM11• Anchorage - Rub-off test with finger• Coverage - Methylene blue(on paper substrates) - Malachite dye test- Shirlastain test07-05-2013 2
  3. 3. • Release - Release force at low stripping speedsproperties (FTM3, FTM10; 300 mm/min.)- High speed release(FTM4, stripping at 5 - 300 m/min.)test tapes from Beiersdorf• Coat weights - X-Ray method- Determination by consumption- By washing-off on some plastic films07-05-2013 3
  4. 4. Scope:This method gives a qualitative evaluation of the degree ofcure of a release coatingMaterial & Equipment: Scotch brand cellophane tape610, ¾” or 1” wideDEGREE OF CURE – QUALITATIVETAPE TEST07-05-2013 4
  5. 5. Remove first 2-3 layers of tape from the roll and discard.Remove 8-10 inches length of tape by pulling it smoothly from the roll. Do nottouch the adhesive side to itself, fingers, or other foreign objects. Place thetape, adhesive side down, onto the coated silicone liner, retaining hold of oneend of the tape.Stroke the tape with moderate finger pressure 5 times to assure uniformsurface contact.Remove the tape, turn it over, and double it back on itself, so the sticky sidesjust touch (no additional pressure to be applied).Pull the tape smoothly apart. Note the force required to pull it apart andnoise that occurs. Re-touch the sticky sides and pull apart several times toconfirm the results.Compare this result with a fresh, untouched strip of tape from the same roll.Record and report the degree of adhesive detackification: none, very slight,slight, some, or gross as defined below.PROCEDURE07-05-2013 5
  6. 6. None :Tape has essentially the same adhesive force as fresh tape.No crackling noise is heard when the tape is pulled apart.Very Slight :Tape has slightly less adhesive force than fresh tape. A slight crackling noisemay or may not be heard.Slight :Tape has less adhesive force than fresh tape. A crackling noise is usually heard.Some :Tape has significantly less adhesive force than fresh tape. A crackling(“zippery”) noise is heard.Gross :Tape will not adhere to itself. Very little to no force isrequired to pull it apart compared to fresh tape.07-05-2013 6
  7. 7. 07-05-2013 7
  8. 8. RUB OFF TESTSCOPE:This test determines the anchorage of a silicone releasecoating to the substrate on which it has been coated.At a certain stage in cure, some coatings do not smear,but have not yet developed good adhesion to the substrate.For other instance, a fully cured coating may not adhere to aspecific substrate.ANCHORAGE OF SILICONE RELEASECOATINGTO THE SUBSTRATE07-05-2013 8
  9. 9. PROCEDURE:Rub the coating with one finger several timeson the same spot of the coated substrate.If the coating balls up under the finger, adhesion isinsufficient.Report the degree of rub off as none, some, gross.07-05-2013 9
  10. 10. DYE TEST FOR COATING UNIFORMITYAND COVERAGE –MALACHITE GREEN SOLUTION(for inspecting large areas of coated substrate)SCOPE:This test determines silicone coverage, coating defectssuch as skips, streaks, scratches, etc., and coating uniformity.Silicone coated surface is smeared with a specified dye solutionand wiped dry with an absorbent paper. The effectiveness of thecoating is then judged by the amount of color retained by thesubstrate and the amount of color striking through the substrate.MATERIALS & EQUIPMENT:Solution of malachite green oxalate* (concentration and solvent to beadjusted to meet requirements of a particular application)Specialty Coatings Test Methods07-05-2013 10
  11. 11. PROCEDURE:Apply the stain to the coated surface with a soft applicator withoutrubbing. Let it sit for approximately 15 seconds.Wipe excess off.Observe general background color and any dark pattern on both sidesof coated substrate.Compare to standard.INTERPRETATION OF RESULTS: Properly coated substrate willabsorbvery little or none of the dye solution.Improperly coated substrate will retain the dye and show defectssuch as pin holes or skips where no coating has been applied.07-05-2013 11
  12. 12. Malachite Green Oxalate : 2.0 parts by weightTritonX-100 or similar wetting agent : 0.1 parts by weightWater or/and isopropyl alcohol : 97.9 parts by weight**Sponge, cloth or other absorbent materialCobb sizing tester (Gurley Precision Instruments 1-800-759-1844 orother supplier) or Hercules sample holder, part #40 (Hercules Inc.Paper and Equipment Group 770-447-6135) may be used to hold the dyesolution on the substrate for a specified period of time.Typical formulation:07-05-2013 12
  13. 13. 07-05-2013 13
  14. 14. Dye Stain Test for Silicone Coverageof Paper Substrates• Test ink e. g. 0.1 % Methylene blue in water• One minute contact time with silicone coatedsurface• Cobb tester to hold ink on substrate• Only for paper substrates, not with films orpolycoated papersA certain level of stainingmay be acceptable.A standard should bedefined for each product.07-05-2013 14
  15. 15. Type of Microscope• Coaxial illumination(transmitted light)• ~ 140 times magnificationPortable microscope• Model CV-ST-miniObjective 2 x and 4 xTube CV-K-120, Color-CCD-Camera 1/3“Calibrationscale 0.01mm – 2mm lengthSoftware Metric, Industryframegrabber~ 2800,- EUR plus VATMicroscope for Silicone Coverageon Filmic Substrates07-05-2013 15
  16. 16. Type of Microscope• Coaxial illumination(transmitted light)• ~ 50 times magnificationFurther advantages with• Polarised light• Stereo microscopePortable microscope• Model 2054-40-CIL, ~ 850 € plus VAT, optional• Nikon Coolpix 880 digital camera, adapter ringOn Film Substrate07-05-2013 16
  17. 17. Test Equipment for water-basedAdhesive Coating• Coatmaster 509 MC controlled filmapplicator• 15 application speeds from2.5 to 80 mm/s• Substrate fixed by vacuum table• Holds various rakel systems• Price Coatmaster 509 MC ~ 5 000 €vacuum sucking plate ~ 1 000 €07-05-2013 17
  18. 18. (for inspecting small areas of coated substrate)SCOPE: This test determines silicone coating coverage, coatingdefects such as skips, streaks, scratches, etc., and coatinguniformity.The dye solution is applied to the coating for a specified amountof time, wiped dry and the coating surface is then evaluated for anyimperfections.DYE TEST FOR COATING UNIFORMITY ANDCOVERAGE07-05-2013 18
  19. 19. Procedure:Cut three samples from the roll, one from each side of the web and one from thecenter.Place one sample in the clamp, silicone coated side up.Pour the solution into the clamp. Start the timer.After the specified time, pour the dye back into the container, remove the paperfrom the clamp, and wipe it dry with a soft absorbent paper.Inspect both sides of the sample.Compare the results to standards and report as excellent, good, fair, poor,unacceptable.Interpretation of Results:Properly applied and cured silicone release coating will be stained yellow.Improperly coated substrate will retain the dye and show defects suchas pin holes or skips where no or less coating has been applied.These areas will be stained brown.07-05-2013 19
  20. 20. 07-05-2013 20
  21. 21. RELEASE TEST – TAPE TESTSCOPE:The release test determines the force required to separate a pressure sensitive adhesivemass from a silicone release coated substrate. A standard pressure sensitive tape* is usedfor testing.MATERIALS & EQUIPMENT:Standard pressure sensitive tape, 1”width Release liner to be tested Laminator or rubberroller (roller HR-100, Chemsultants 440-352-8572, or other supplier)Two weights to apply ¼ psi pressure (24oz. rectangular weight for 1”x6” sample)Two glass panel 2”x10”Circulating hot air oven capable of maintaining a temperature of 70oC (158oF) ifaccelerated aging is required Release tester capable of measuring release at a specifiedspeed and angle (Release and Adhesion Tester, TMI, 1-800-678-3221; ZPE-1000 HighRate Peel Tester, Instrumentals, Inc. or othersuitable instrument)07-05-2013 21
  22. 22. PROCEDURE:Strip the first layer of adhesive tape from the roll and discard.Cut two 10” strips of tape and apply them to the release coated paper with the adhesiveside in contact with the paper.Cut the paper with the tape over it into strips slightly wider than the tape.Pass the samples through the laminator or use the rubber roller to laminate them-maketwo passes over the tapes without exerting any pressure other than that exerted by theroller itself.Place the samples on glass plates under the weight (1/4 psi) for a required period of time,usually 20 hrs.Test release at specified conditions (speed, angle, peeling the liner from the adhesive orface stock from liner). Calculate average, record result.Note: If accelerated aging is required, place laminates under theweight (1/4 psi) in the 70oC oven for a specified time period,usually 20 hrs, take them out and let them cool down for atleast 1 hr before testing the release.Typically used standard tapes: Tesa7475 (acrylic adhesive),Tesa4651 (rubber based adhesive), J&J tapes, or any othersuitable pressure sensitive tape.07-05-2013 22
  23. 23. 07-05-2013 23
  24. 24. SCOPE: The release test determines the force required to separate apressure sensitive adhesive mass from a silicone release coatedsubstrate.MATERIALS & EQUIPMENT:Wet adhesiveDraw down applicator or Meyer rod capable of applying a specifiedthickness of adhesiveFace stockCirculating hot air oven capable of maintaining a temperaturerequired for adhesive dryingTimerLaminator or rubber roller* (4.5 lbs.)Release tester capable of measuring release at a specified speedand angle**RELEASE TEST – WET ADHESIVE07-05-2013 24
  25. 25. PROCEDURE:Draw down adhesive in machine direction (MD) on the surface of therelease coated substrate assuring the required wet/dry thicknessImmediately place the coated sample in 90o C oven to avoid “fish eyes”,start the timerDry the adhesive in the oven at the temperature/time specified for theadhesive usedRemove the sample from the oven and laminate the face stock to theadhesive surface, pass it through the laminator to exert uniformlamination pressure or use a rubber rollerCut 1”x10” samples in (MD), minimum two samplesTest release at specified conditions (speed, angle, peeling theliner from the adhesive or face stock from liner)Calculate average, record result* Rubber roller HR-100, Chemsultants 440-352-8572, or other supplier** Release and Adhesion Tester, TMI 1-800-678-3221, ZPE-1000 HighRate Peel Tester, Instrumentors, Inc., or other suitable instrument07-05-2013 25
  26. 26. DEGREE OF CURE - SMEAR (SMUDGE) TESTSCOPE:This test determines the extend of cure of a silicone release coatingPROCEDURE:Make a single, firm stroke across the coated paper with one finger.Inspect the smudge area with low angle light.Report results as none, slight, or gross.Fully cured coating will show no finger mark.Inadequately cured coating will show greasy streak.07-05-2013 26
  27. 27. SUBSEQUENT ADHESIONSCOPE: Subsequent adhesion is a measure of the adhesion of a pressuresensitive adhesive after it has been in contact with a release coating.The test is used to check for any migration of silicone onto theadhesive.MATERIALS & EQUIPMENT:Standard pressure sensitive tape or previously prepared with a specifiedadhesive a 1” wide strip of release liner/polyester film laminateStandard stainless steel panels 2”x6” (TP-26 Adhesion Panels available fromChemsultants 440-352-8572) 4.5 pound rubber roller (HR-100 available fromChemsultants 440-352-8572)Peel/release tester capable of strip rate of 12 inches per minute at 180 degreeangle07-05-2013 27
  28. 28. PROCEDURE:Place the tape/ polyester film stripped from the coated release liner onto aclean stainless steel panel right after measuring the release Pass the rollerover the tape without added pressure (free weight of the roller only), once ineach directionAllow the tape to age on the panel for 20 minutesMeasure the force required to pull the tape/polyester film strip (test tape)from the panel, record result in grams per inchRepeat the procedure for a tape/polyester film coated with a specifiedadhesive which has never been in contact with the release liner (control),record resultCalculate subsequent adhesion: %SA=100 x force required to pull test tape /force required to pull control tapeNOTE: Always test at least duplicate samples and calculate theaverage value.07-05-2013 28
  29. 29. INTERPRETATION OF RESULTS:1. Low release values coupled with high subsequent adhesion valuesindicate that:Silicone release coating has been adequately cured and is nottransferring to the adhesiveSilicone coverage is satisfactory2. High release values can be attributed to several factors:Inadequate or unevencoatingExhausted bath life Ineffective silicone coating or catalyst3. Low subsequent adhesion values may indicate:Incomplete cure resulting in migration of the silicone coating into the adhesiveRough substrate which has molded an irregular surface on the adhesivereducing the area of contact with the steel panelDeterioration of the adhesive - if the samples were aged in anelevated temperature07-05-2013 29
  30. 30. Note: If accelerated aging is required, place laminates under theweight (1/4 psi) in the 70oC oven for a specified time period,Typically used standard tapes: Tesa7475 (acrylic adhesive),Tesa4651 (rubber based adhesive), J&J tapes, or any other suitablepressure sensitive tape.07-05-2013 30
  31. 31. 07-05-2013 31
  32. 32. Test Equipment for Releaseand Subsequent Adhesion• Horizontal tensile tester for release forceand subsequent adhesion accordingto FINAT• Load cell maximum 5 N or 50 N• Speed of table is electronically set to300 mm/min., may be switched to 50,150 mm/min. or variable from 50 to1 000 mm/min. (optional).• Specimen of min. 10 cm length07-05-2013 32
  33. 33. Procedure• Take a representative sample of the silicone coated substrate• Apply at least two test strips of the PSA tape (repeated test)• Avoid air bubbles under the test tape• Cut sample and age under pressure in an oven• After 16 h ageing the samples are reconditioned at room temperature for 2 h• Fix the specimen with a double sided tape on the tensile tester• Peel at 180° angle04080120160200RC 902/ RC 711TESA 7476TESA 7475TESA 4154[cN/in] Finat 10/ 1d 40 °C80/ 20 60/ 40 40/ 60 20/ 80Test Equipment• Tensile tester to peel a laminate at an angle of 180°• Separation rate of 300 mm/min.• PSA tape, 25 mm wide (e. g. Tesa 7475, 4154 or7476)• Double side tape for fixing the substrate (e. g. Tesa4960 or Tesa 4970)• Oven to maintain aging temperature of 40 °C• Metal pressure plates loaded to give a pressure of 70g/cm²Release Value Testing Accordingto FINAT #1007-05-2013 33
  34. 34. Quick Subsequent Adhesion TestQSA) similar FINAT #11Cure Speed with 120 W/cm(RC Siliocnes with 30 % RC 711)40506070809010075 100 125 150 175 200Line Speed [m/min.]QSA[%]RC 715RC 902RC 726RC 706Procedure• Take a representative sample of the liner• Apply 10 cm Tesa 7475 by means of FINAT roller(roll 5 times in each direction)• After a contact time of 60 s the test tape is released• A piece of acetate film (5 cm * 13 cm) is fixed by a double side tape on the release tester• The test tape is laid on the acetate film and laminated with the FINAT roller (roll 5 times in each direction)• Release test after 30 s contact• QSA is the release force divided by the average five blank (no contact to silicone)Test Equipment• Test Equipment• Tensile tester to peel a laminate at an angle of 180°• Separation rate of 300 mm/min.• OPP Film ≥ 50 µm (CR 50 O; UCB Films/ 50170Kerpen)• 2 kg FINAT test roller• Suitable tape e. g. Tesa 7475• Double side tape (e.g. Tesa 4960)• Stopwatch07-05-2013 34
  35. 35. Test Equipment for High Speed Release• High Speed Release Test System• Peel speeds from 0.04 to 5.0 m/sec. (2.4 to 300m/min.) ramped and constant velocity• Standard constant speed settings2.4/10/100/300 m/min.• Liner peeled off adhesive face• Specimen of about 30 cm length• Price ~ 30 000 €0204060801000 50 100 150 200 250 300Stripping Speed [m/min]RC 902/ RC 709/ RC 711 10/60/30RC 902/ RC 709/ RC 711 20/50/30RC 902/ RC 709/ RC 711 40/30/30RC 902/ RC 711 70:30[cN/in] TESA 7475/ 1d 40°C07-05-2013 35
  36. 36. For more Information : www.psadhesive.comContact DetailsEmail : shrikantathavale@psadhesive.comPersonal Email : psatechno@gmail.comCell : 00 91 75882882043607-05-2013
  37. 37. 3707-05-2013Tell me moreThe heart of a meaningful conversationDesigned to share knowledge andUnderstanding for mutual benefit