A laminate is a material that is constructed by uniting two or more layers of material together. The process of creating a laminate is lamination, which generally refers to placing something between layers of plastic and bonding them with heat and/or pressure, usually with an adhesive. The materials used in laminates can be the same or different. An example of lamination using different materials would be the application of a layer of plastic film — the “laminate” — on either side of a sheet of glass — the laminated subject. Vehicle windshields are commonly made by laminating a tough plastic film between two layers of glass.
More appropriate to this industry, laminating printed paper and film, are frequently used to prevent creasing, sun damage, wrinkling, abrading etc. Laminates can be used to add properties to a surface, that would not have them otherwise. These may be simple effects such as surface gloss, surface matte; more complicated properties such as UV protection or grease resistance; or even specialty effects such as unique surfaced films which can be written on with dry-erase markers or chalk. Further, multiple translucent printed images may be laminated in layers to achieve certain visual effects or to hold holographic images. Many commercial printing businesses keep a variety of laminates on hand, as the process for bonding many types of substrates is generally similar when working with thin films. These laminate materials may be linered products which use a backing which does not adhere to the adhesive, but leaves the liner as waste; a self-wound product where the adhesive doesn’t adhere to the face of the material; or press applied where an adhesive is applied and laminated to a film on press. A large percentage of cold laminate for use in the print industry is BOPP, PET and PVC, although other materials are available.
Cold-roll laminators are frequently used to laminate plastic films coated with an adhesive. This method, apart from having the obvious benefit of not requiring expensive equipment, is also suitable for items which would be damaged by heat. Cold laminators range from simple two roller, hand crank machines up to large and complex motor driven machines with high precision rollers, adjustable roller pressure and other advanced features. Some key factors in getting a good quality lamination include:
Alignment between the laminate and the substrate, otherwise, wrinkles will result.
Appropriate tension on webs and nip-points will prevent curling of the finished product.
Even/appropriate lamination pressure. Typical lamination pressures are 25-35 psi
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Web and laminate must meet at the laminating nip, otherwise air will be entrained prior to lamination.