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1 HIGHLY CONFIDENTIAL UV Coating Quality Control Seminar

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Page 1: 0 HIGHLY CONFIDENTIAL UV Coating Quality Control Seminar

1HIGHLY CONFIDENTIAL

UV Coating Quality Control Seminar

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Overview

• 60º Gloss Meter Testing of UV Coatings

• UV Cure Level Testing

• Scratch Resistance Testing (Level of Cure)

• Potassium Permanganate Stain Testing for UV Coating Consistency

• UV Coating Adhesion Testing

• Press Set Up and QC Procedures for UV Integrated Label System.

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Testing

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60º Gloss Meter Testing

• Ensure that the area to be tested is representative of the total printed sample or is in accordance with the specifications, and that the print sample is large enough to cover the gloss meter aperture.

• Place the test sample, print side up, on a flat area.

• Following manufacturer’s operating instructions, measure the gloss of the printed sample in the "machine" direction. Record the values separately.

• Gloss readings above 70 are typically acceptable for direct mail applications.

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UV Cure Level Testing

• Saturate an industrial strength napkin with Methyl Ethyl Ketone (MEK).

• With “average effort,” rub back and forth with the napkin containing MEK.

• Count number of cycle rubs it takes for the coating to begin coming off.

• 11-15 cycles back and forth is average. Below this represents a poor cure situation.

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Scratch Resistance Testing

• With a nickel coin, rub back and forth on the surface of the UV coating.

• Coating should remain intact for six to eight cycles.

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Stain Testing for UV Coating Consistency

• Prepare a 1% solution of potassium permanganate (KMn04) in de-ionized or distilled water.

• Select a portion of the print for testing that is either over white paper or over solid opaque white ink.

• Apply a sufficient quantity of the KMn04 solution to both the standard and sample cured film to cover an area approximately 1/4 inch in diameter using a disposable pipette.

• Allow the solution to remain in contact with the coating for exactly five (5) minutes using a stopwatch. Blot off solution with a paper towel.

• In the area where the solution was in contact with the coating, a brown stain will be apparent. Measure the yellow density of the brown stain immediately after the potassium permanganate solution is removed.

• This is a comparative test.

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UV Coating Adhesion Testing

• Place print on flat surface.

• Apply a six inch strip of tape smoothly onto the print.

• Grasp one end of the tape with thumb and forefinger. Using the other hand, hold print firmly on the surface.

• Pull the tape off print at a 180° angle at a moderate speed.

• Examine the print and tape for evidence of ink removal. Ink/overprint removal of 10% or less are acceptable.

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Press Set Up and Quality

Control Procedures

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Press Set Up and QC Procedures for ILFS Integrated Label System (with UV Silicone)

For Flexo Applied Applications

• Utilize a photopolymeric plate

Handling and Substrate Requirements:

• L9091L UV free radical and PC-605 UV cationic silicone release coatings are one-component systems that are thixotropic in rheology, offering excellent hold out characteristics on uncoated paper stock. These products should be mixed for a few minutes prior to running. Also, it is best to keep constant agitation on these products while running.

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• Use Nitrile rubber gloves when handling UV during mixing process

• Do not leave pails or drums of UV open when not in use due to the inherent UV light sensitivity of this type of product.

• Shelf life for these products is three to six months.

UV Curing Requirements:

• 200 fpm per 300 watts/inch lamp

Press Set Up and QC Procedures for ILFS Integrated Label System (with UV Silicone)

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On Line Quality Control Procedure (before adhesive is applied):

• Use a micrometer to ensure that the volume of UV silicone release coating remains at no less than 0.15 mil.

• Check reverse side of web after UV application and make sure no UV silicone has penetrated. This should be done visually as well as with a permanent pressure sensitive label (shipping label) by sticking the label on the reverse side of the web and making sure fiber tear occurs.

• Using your fingernail, scratch the surface of the cured UV to make sure only an insignificant amount of UV silicone is coming off. This is a quick test to confirm that cross-linking has taken place.

Press Set Up and QC Procedures for ILFS Integrated Label System (with UV Silicone)

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Visually check the curing of the coating. If coating remains in liquid state after the UV lamps, take the following steps:

• Make sure the lamps are operating properly.

• Make sure the paper has not been exposed to a high degree of relative humidity. If high humidity is an issue, increase the UV application until cross-linking is observed.

• Check the effectiveness of the release coating with a permanent pressure sensitive “shipping label” before hot melt coater is engaged. If clean release is observed, turn on the hot melt coater.

Press Set Up and QC Procedures for ILFS Integrated Label System (with UV Silicone)

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As Final Quality Control Check After Hot Melt Coater is Engaged:

• Peel hot melt labels off integrated label piece and make sure no streaks are observed on the release coating surface.

• Directly off line, “pinch” long way on label; label should almost fall off.

• Make sure dies are not set too deep so as to “punch through” back of piece. This will result in fiber tear of the label.

Press Set Up and QC Procedures for ILFS Integrated Label System (with UV Silicone)

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Required Equipment for Tests

• 60º gloss meter is available from UV Process Supply www.uvprocess.com

• Potassium permanganate stain testing kit can be purchased on www.uvprocess.com but is expensive. Or you can purchase pure potassium permanganate and dilute down to a 1% solutions (99% water/1% potassium permanganate). This is available from JT Baker at www.mallbaker.com

• Micrometer is available from Mitutoyo (815-444-9538). Part # 293-761-30. Measurable down to 0.05 mil.

• 3M 610 Tape is available from ULine (800-958-5463) or www.uline.com