Laminating Technique for Face Adhesive Verification Transfer Adhesive Product Information Bulletin Folder Lorem 9.1 ipsum Date 0000 June 2014 Replaces IF 9.1 dated November 2012 Lamination Process Basic requirements for proper laminations: 1. Clean sheeting. 2. Proper equipment and lamination conditions. Typical Lamination Machine Unwind Lamination Process Conditions These problems can Problems be solved by adjusting Wrinkles, misalignment, Roll Condition poor bond, cross web curl Internal laminate In and Out Feed stresses, down web curl, edge lifting Wrinkles, bubbles, Thread Up alignment Weak bond, adhesive Nip Adjustment ooze, steering trouble, wrinkles Trapped air bubbles, Contact Point wrinkles, adhesive picking A few basic requirements must be followed. There are several variables that can affect proper lamination conditions. Most of these variables are a result of laminator condition and adjustments. These problems can cause unsatisfactory laminations. Sheet Stock Infeed Shelf With a typical laminator, there can be many variations, but all should use this basic thread up. Roll Condition Adjustable Roll Laminating Adhesive Outfeed Shelf Smooth, clean, parallel nip rolls with properly adjusted pressure. Good lamination must start with nip rolls in excellent condition and adjustment. The upper and lower rolls should be smooth, clean, parallel, and have left and right side pressure adjustability.
Concave Thread Up - Roll Wrap Poor Bond, Adhesive Picking, Trapped Air Bubbles Convex Use good wrap Poor Bond, Edge Lift, Bubbles Canted Concave, convex, or canted rolls will cause problems such as poor adhesion, adhesive picking, lifting, wrinkling, trapped air bubbles and web steering difficulty. Feed - In & Out Steering, Wrinkles, Bubbles It is also very important that the roll of laminating adhesive be threaded into the machine so that there is a good smooth wrap around the rubber roll. This will smooth the adhesive and liner and prepare it to be laid down onto the sheeting. A lesser degree of roll wrap will not accomplish this and wrinkling and bubbling may result. Nip Pressure Use equal pressure left to right In & out = same plane Higher psi on right side of nip Problem: Wrinkles, steering, curl, bubbles Problem: Causes built in stresses, curl of laminate The in and out feed tables must be at the same level or plane and should be of adequate length to hold at least one printed sheet. There will normally be curl stresses if the out feed table is positioned as shown above. Nip roll pressures can be controlled either manually by screw downs or air cylinders. The best design would be single control for simultaneous and uniform adjustment by both actuators. The major problems of non-uniform pressure as shown (exaggerated) here, are wrinkling and steerage of the web. 2
L/A - Substrate Contact Point Contact at nip pressure point Contact point too early Problem: Trapped air bubbles A common application problem is caused if the technique allows the laminating adhesive to contact the sheeting prior to the nip pressure point. Air entrapment can only be minimized or eliminated by keeping the adhesive off the sheeting until it enters the nip contract point. The diagram on the bottom shows how air can be trapped by premature nonpressure contact of the laminate materials. The air will then remain trapped in the laminate as it passes through the nip. Trapped air results in adhesive picking during liner removal. This macro photo shows the liner being removed smoothly from a good lamination. This photo shows the adhesive picking or lifting problems due to an entrapped air bubble. This is a common cause for reject sheets. General Nip Roll Characteristics for PSA Laminating A. Top Roll = Rubber or elastomer Urethane Neoprene Silicone 35-40 Shore A durometer hardness for urethane or neoprene 60-80 Shore A for silicone Top roll applies pressure to laminating adhesive and rubber allows deflection to compensate for caliper variations. B. Bottom (back-up) Roll = Steel or hard rubber Nickel or chromium plated to resist corrosion and nicks and easy to clean. C. Correct roll diameter to roll width ratio is required to prevent roll deflection. Generally 6-8" roll diameter is required for 30" wide laminator. Nip Roll Pressure General = 1-3/4 to 20 pounds per lineal inch (PLI) adjustment range. Screw adjusters Air cylinder adjusters (preferable) Use low pressure for FACE adhesive and sheeting. Must be uniform across web 3
Roll pressure is best determined by trial, and depends on the type of rolls. Roll pressure must be uniform across the web to prevent wrinkles and to give the proper adhesive contact and bond strength. Hand Lamination for Small Sheets and Difficult Registration Plastic Squeegee or Hand Roller Problem: Wrinkles, bubbles L/A Sheet Substrate L/A Sheet Substrate Often small sheets, low volume or precise registry of complex die cut-out sheets preclude the use of a nip roll machine lamination. In simplified form, using either a hand plastic squeegee or small hand roller, the process would look like this. You are using the same principles of nip roll lamination - firm, uniform pressure, keeping the adhesive off the substrate until pressure contact is made to prevent entrapment of air. Summary To Laminate I. Clean sheeting surface. II. Always laminate to exclude air entrapment. III. Provide uniform low nip roll pressure. IV. Provide good roll wrap, (i.e., 180 ), web tension and steering for a wrinkle free laminate. V. Allow minimum adhesive dwell time of 15-30 minutes before liner removal. 24 hours is preferable. Laminator Manufacturers List The following is a partial listing of manufacturers or suppliers of lamination equipment. Converting Technologies, Inc. Goddard, KS 316-722-6907 Wesco Machine Co., Inc. Stow, OH 216-688-6973 Potdevin Machine Co., Inc. Tederboro, NJ 201-288-1941 Ledco, Inc. (Graphic & Clear Craft PSA Laminator) Cleveland, OH 216-881-2100 The Wallace Co. (Walco) Pasadena, CA 818-564-8777 Greig Laminator Madison, WI 608-222-8813 J. Böck ag. 011-41-7142 7042 Altenrhein, Switzerland A basic 30" wide, variable speed, PSA Laminator can be purchased with optional equipment such as heated rolls, extended tables, air brakes for unwinds, and silicone rolls. It is suggested you contact a laminator manufacturer to design equipment for your specific needs. FOR INFORMATION OR ASSISTANCE CALL: 1-877-777-3571 IN CANADA CALL: 1-800-265-1840 Internet: www.3m.com/mvss 4
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