In-mold decoration

Table 5.27 Typical physical properties of a decorative in-mold topcoat...

Moldflex, Decorative in-mold coatings, Waterlac Coatings, Inc. 

Injection-molded articles can be decorated by in-mold labeling or by post-mold decoration. In the former method, printed film is inserted into the mold cavity before injection. The plastic forms an intimate contact with the graphic material. Post-mold decoration includes hot stamping, dry offset printing, and decal printing. 

The basics observed in molded products are always the same only the extent of the features varies depending on the process variables, material properties, and cavity contour. That is the inherent hydrodynamic skin-core structure characteristic of all IM products. However, the ratio of skin thickness to core thickness will vary basically with process conditions and material characteristics, flow rate, and melt-mold temperature difference. These inherent features have given rise to an increase in novel commercial products and applications via coinjection, gas-assisted, low pressure, fusible-core, in-mold decorating, etc. 

Decorating is transferred to molten plastics as it enters the mold. Decoration becomes integral part of product. system foT the transfers. Static charge may be required to hold foil in mold. 

Another consideration is the ability of a material to provide a surface that is compatible with the requirements of the application a smooth finish for extruded profiles, molded-in colors, textured surfaces, etc. The compatibility of the major processes with in-mold coating and other insert-surfacing materials, and their compatibility with surface decoration secondary processes, could also be important. 

Used in molding applications, appliances, TVs, automotive parts, filler, impregnating paper, varnishes, decorative laminates, electrical parts, countertops, toilet seats, adhesive for plywood, sandpaper, brake linings, abrasive wheels No large industrial applications... 

Melt compression molding identifies in-mold laminating and in-line molding of carriers, decorations, etc. The basic technique has been used for over a century. There has been an increased application of textile cover stock and leather substitutes both preferably with a soft touch. This type development was primarily initiated by the automotive industry with the objective to be prepared for future trends. Other industries such as furniture and packaging manufacturers use this process. 

The increasing use of plastics as construction materials has led to a renewed interest in decorative finishes for plastic products. There are a wide variety of secondary operations that can be used for adding decoration to molded parts. Progress is also being made in providing decorative surfaces in the mold itself. The first use of this is in woodlike panels for wall decoration and furniture parts such as cabinet doors. 

Insert molding, or in-mold decoration, helps overcome the flow lines common to metallic colored intricate injection-molded parts. By this process a film with a uniform orientation is thermoformed and fused with the surface of the injection-molded part. 

The process is suitable for a variety of applications, ranging from simple label film to decoration on molded parts such as plaques, medallions or wall tile. However, the flexible printing plates used in flexography do not permit the very fine detail that can be achieved on metal surfaces such as used in gravure printing. There are also limitations to the size and shape of articles that can be printed. 

In-mold decoration can be done with either injection molding of thermoplastics or compression molding of thermosets. Thermosetting plastics are decorated with a two-stage process. For melamine products, for example, the mold is loaded with the molding powder in the usual manner and closed. It is opened after a partial cure, and the decorative "foil or overlay is placed in position. 

The overlay, in all cases, is a printed or decorated film (0.003-0.005 in. thick) of the same polymer. Thus, polystyrene film is used for a polystyrene product, and polypropylene film for a polypropylene product. A similar procedure may also be used for decorating blow-molded products. 

In-the-mold decorating Film or foil inserted in mold is transferred to molten plastics as it enters the mold. Decoration becomes integral part of product. Automatic or manual feed system for the transfers. Static charge may be required to hold foil in mold. Most plastics, especially polyolefins and melamines. For parts where decoration must withstand extremely high wear. Single- or multicolor decoration. 

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