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A glossary of terms for materials used in decorative laminating.

Laminating equipment and two new classes of decorative overlays are the most recent additions to the LMA's "Glossary of Terms."

The Laminating Materials Association in its continuing efforts to assist the industry to achieve a communality of terms has published a new section on laminating equipment in its "Glossary of Terms," as well as adding definitions for thermofused overlay films and wrapping films in the decorative overlays/vinyl films category.

These new sections are published below. The Association solicits comments from readers, which can be made to LMA President George Carter, 767 Park Avenue, Oradell, NJ 07649, phone 201/265-7766.

A copy of the entire glossary can be obtained free of charge by circling #249 on the Reader's Service Card.

LAMINATING EQUIPMENT

SURFACE PREPARATION EQUIPMENT

The function of this equipment is to prepare particleboard, medium density fiberboard (MDF) and other substrates for successful lamination. When used properly, this equipment produces a product surface that will be smooth and dust free. Sometimes the board is warmed before lamination. This will result in laminations that show no telegraphing off dust or fibers.

Sanding Equipment

Sanding equipment is used to prepare a substrate's surface for laminating. It is particularly important when particleboard and MDF are used in conjunction with some of the thinner overlays. The two primary types of sanding equipment used in flat panel laminating sanders

* Contact drum sanders

* Platen head wide belt sanders

Drum and stroke sanders, although available, are generally not used in flat panel lamination. Sanding the substrate is generally done at the start of the preparation process. However, if it is necessary to fill the board, a second sanding operation may take place to insure that the board is totally smooth before laminating.

Cleaning Equipment

The purpose of the panel cleaner is to remove dust and chips from the board surface after sanding. This is typically a sweeper vacuum-type piece of equipment. This process can also occur after filling, if that step is necessary.

The cleaning operation may also involve the use of brushing equipment, whose purpose is to separate small particles from the face of the board so they will be picked up by the vacuum.

Filling Equipment

This equipment is used to fill void areas on the board surface. This procedure is not as necessary with modern boards that are manufactured with "fines" on the board surface. Filling requires oven curing and sanding of the filled surface to insure a successful bond between the board and the overlay. The three most common types of filling materials are ultra violet (U.V.) curable, water base, and solvent base.

Board Drying Equipment

Drying equipment is used to dry and cure any filling agent used to make the substrate smooth. The most frequently used systems are:

* High intensity infrared

* High velocity hot air

* U.V. curing oven

Board Preheating Equipment

This is required in cold climates especially, but is useful in all climates. The purpose is to stabilize the entire board surface for successful, consistent laminating conditions year-round.

Board Resinating

Resinating occurs when a panel (PB, MDF, etc.) is passed under high pressure between two polished steel rollers that are heated to relatively high temperatures. The process causes the two resins present (specie and added resins) to become liquid for the instant of pressure, and the resin is calendared under the influence of the polished steel roll and pressure. Simultaneously,there is an actual crushing of the top wood fiber cells of the board.

Resinating improves sanding grit effectiveness or eliminates sanding altogether. This process can be used prior to laminating on either a wet or dry system.

COATING EQUIPMENT

The purpose of coating equipment is to provide a thin layer of adhesive that will bond an overlay to a substrate. There are a variety of adhesives and overlays, thus there are several different types of coating systems. When using a water based and adhesive, part of the moisture is generally flashed off before laminating takes place. This aids in minimizing or eliminating fiberpop for telegraphing after lamination.

Definitions of the adhesives used in laminating are found in an earlier section of this Glossary.

Epoxy Adhesive For Vinyl Overlays

* Single pass board coating

* Single pass web coating

PVA, PVAC, Urea Formaldehyde adhesives

* Single pass board coating

* Single pass web coating

* Single pass board/single pass web coating

* Two-pass (two coaters) board coating

Adhesive is applied to the board, to the web, or both. In an epoxy application, between 1 1/2 to 2 wet mils are applied to the web. With water based adhesives, the application is 3/4 to 2 1/2 mils of wet adhesive.

FLAT PANEL LAMINATING EQUIPMENT

Liquid Adhesive Roll Laminating Equipment

The roll laminating equipment consists of one (sometimes two or three) heated roll combining stations, where continuous rolls of paper or vinyl film are laminated to the substrates. The liquid adhesive is applied to the board, to the web, or both, prior to the combining of the film and substrate.

The lamination and bond are created as paper or vinyl film is pulled from an unwind stand, and married with the substrate as they meet and pass through the rotary roll combining station. After lamination is complete, the panels are

separated and stacked.

The equipment arrangement can be for a single top lamination or top and bottom lamination.

Heat Reactive Adhesive Roll Laminating Equipment

Heat reactive equipment uses decorative overlays that have a dry adhesive already applied to the back of the overlay. The laminating machine contains heated rollers which active the adhesive, roll the overlay onto the substrate, and apply pressure while the bond is created. Bond and cure are rapid. No ovens are required for curing.

Continuous Belt Roll Laminating Systems

The continuous belt laminating system is a more involved and sophisticated equipment arrangement, where panels of particleboard, MDF, hardboard, etc., are fed into the line continuously end to end. The overlays are applied from rolls, either for single or double sided lamination, onto the adhesive coated substrate prior to bonding. Depending on the adhesive system used, the process may be completed (bonding) by using either hot or cold calendar rolls. For the latest state of the art methods, a hot press is desired.

After the bonding takes place, the boards are separated, trimmed, and stacked.

Hot Platen Press

Hot platen presses are equipped with internally heated single-opening or multi-opening, with either flat or molded press platens. The pressing time and temperature are determined by the adhesive and the chemical or heat reactions, as well as by the thickness of the laminating materials. Depending on the grade of automation, the process can be charged and discharged either manually or automatically.

A glue spreader is usually used to apply common adhesives to the board prior to lamination. The adhesives used are, urea formaldehyde, PVA, PVAC, and phenolic resins.

Low Pressure Press

This system earned its name from the distinction between high pressure laminates, pressed separately with pressures between 700-1400 psi, and los pressure lamination at 430 psi. Low pressure lamination is a process whereby the resin saturated films are pressed straight onto the substrate (particleboard of MDF) with 430 psi and a lower temperature, generally around 390F. In this fashion, the overlay is "thermofused" directly to the core.

The resin is the bonding material, and liquefies under pressure and heat. The surface structure of the final product is set by the caul plates, which are fixed to the hot press platens. The most common resins are melamine and polyester. Phenolic resin surface films are mainly used for concrete forming boards in the construction industry.

Membrane Press

Membrane press technology, formerly known as the vacuum press system, is used for the lamination of molded (three-dimensionally shaped) substrates with veneers, vinyls, and other materials. The adhesives are applied either to the core or to the laminating materials. The pressing process is performed with a hot rubber or silicone membrane which forms the laminating material under pressure and heat over the molded substrate.

The adhesives used for veneers are primarily PVA and urea formaldehyde. Vinyls are usually bonded with water based polyurethane, which is dried after application and reactivated with heat during the pressing process.

Cold Press

The cold press system has the advantages of being a smaller investment and using less complicated technology, but has a longer pressing time. The operators apply adhesive (PVA) with a glue spreader onto the core and build a stack of laminated, unbonded boards. The stacks are placed in the press and pressed cold for approximately 20-30 minutes. During that time, the next stack is prepared and can be placed in a second press or wait for the one in use.

Surface Foiling Equipment

The equipment takes a heat transfer foil (hot stamping foil) and transfers it to the surface of a smooth substrate. The foil is transferred from the carrier film through heat and pressure. Because the foil is so thin, it is very important that the surface be extremely clean of all dust particles.

There are three additional types of foiling machines that can cover board surfaces as well as their edges.

* Bluff cut (overhead) machines: specialized machines to shape, sand, and foil crosscuts used in drawer fronts, doors, and panels.

* Random foilers: foils serpentine, oval, and round tops either by use of a pattern (template) or by means of computer control.

* Molding foilers: transfers a heat transfer foil to moldings, such as picture frame stock. Shaped silicone wheels in various numbers apply the foil to the molding.

EDGE LAMINATING EQUIPMENT

The function of this equipment is to provide a finished edge to a panel or part of a panel that has been surface laminated. A product with a fair degree of inner porosity, such as particleboard, may need to be edgebanded, with a band thick enough to conceal the voids between particles. Products such as MDF and hardboard can be treated either with standard edging materials or with heat transfer foils, since they have tight cores and are completely homogeneous.

The definitions of heat transfer foil, edgebanding, and films for wrapping are found in the front of the Glossary. Heat transfers foils are also known as hot stamping foils.

Edge Foilers

These are single or double sided machines that typically shape, sand, and foil to a straight or profiled edge. The foil is transferred by heated silicone wheels using pressure to match the desired edge profile. Medium density fiberboard is the most common substrate used in edge foiling. The number of foiling stations, or heated silicone wheels, is determined by the complexity of the profile and production requirements.

Edgebanders

Edgebanders apply a variety of types of edging materials to the edges of panels. Types of edgebanding materials include HPL, PVC, Melamine, Polyester, and solid wood and wood veneers.

Types of edgebanders include single and double sided machines, hot air, PVC, contour, straight line and softforming variations. Edgebanders can be manual or automatic. They can apply edgings with or without coated adhesives. Many larger edgebanders have front end tenoning capabilities for sizing and shaping.

Softforming Edgebanders

Single and double sided softforming edgebanders are capable of applying either a flat or shaped edge, such as an Ogee. Most softformers have sizing and shaping stations which mill the edge prior to the application of the edgeband. Softform edgebanders can be either PVA or Hot Melt systems.

Profile Wrappers

Profile wrap machines apply an overlay to a preformed substrate, typically in lineal molding ("stick') form. A preshaped molding, in a variety of substrates, including but not limited to, solid wood, MDF, particleboard, extruded plastics, and various metals, is fed into the machine in stick form. A flexible overlay of paper, vinyl, wood, veneer, or metallic is concurrently fed into the machine and applied through pressure rollers to the surface of the molding.

Profile wrappers are generally Hot Melt or PVA adhesive systems. Profile wrapped parts can be cut to size with finished ends or left in fixed length sticks form.

POSTFORMING EQUIPMENT

Conventional postforming

This is the process where a laminated surface is formed to a shaped substrate material. It is one of three ways of putting a soft, round edge on a panel. The other two ways are softforming or profiling. There are two types of machines used for conventional postforming, both of which require that the substrate material be preshaped and have the laminate already applied, with the necessary overhang.

The first is a stationary machine where a heated bar follows the preshaped core and is used with either contact adhesives or PVAC. PVAC is generally preferred since thermal reactivation is not a problem. Stationary machines can use a variety of surface materials and are easy to set up and operate.

Throughfeed postforming is used where higher production rates are required and includes the following stations: sizing of laminate, glue application by either roller or spray nozzle, activation zone utilizing quartz lamps and hot air blowers, forming zone, and trimming.

Direct Postforming

Direct postforming is a new concept which involves the same processes of conventional postforming, with the primary difference being that the substrate is preshaped on the same machine, leaving only the laminate to be wrapped. The machine can also include a gluing area for the insertion of an MDF strip or, depending on the quality of the core, can go directly to the glue application where the processes would be the same as conventional postforming. This equipment requires fewer processing stations than conventional postforming machines.

DECORATIVE OVERLAYS

VINYL FILMS

Vinyl film made of polyvinyl chloride (PVC) is used for decorative surfacing and may be either clear or solid color. If it is clear, it is printed on the reverse side to protect the print. If it is a solid color, the printing is on the top.

Vinyls films are divided into six categories:

2 mil Reverse Printed Rigid Film

Unembossed, extruded, or calendared rigid PVC. The print design and ground coat are printed on the back of the film in reverse order. This film is used for wall paneling (mostly in recreational vehicles), kitchen cabinets, furniture, and mobile homes.

Semirigid Clear Film

Calendared semirigid PVC. The film is reverse printed; that is, the ground coat and design are printed on the back of the film in reverse order. The film is frequently embossed and can be coated with scuff resistant coatings. These films range from 4 to 8 mils in thickness. Some can be mitre folded.

Sandwich Film

Calendared semirigid two-ply laminate. The opaque base film is top printed and a clear overlay is laminated on top. This film is designed for mitre folding and flat sheet lamination. These films range from 5.5 to 8 mils in thickness. Some are available with scuff resistant top coating.

Solid Color Film

Calendared semirigid film that is custom color matched in a variety of hues. The film is integrally colored and can be top printed and/or embossed. Top printed film is used extensively in mobile homes, recreational vehicles, commercial paneling, and movable walls. Plain solids are used in furniture, kitchen cabinets, fixtures and displays, and office furniture applications. Thicknesses range from 3.5 to 8.0 mils. Some films are available with scuff resistant top coatings.

Thermoformed Overlay Films

Calendared or extruded solid color rigid vinyl films in single-ply or two-ply construction. Gauges range from 0.010-in. to 0.030-in. and film may be printed in wood grain or decorative patterns. Films may be embossed and may be coated with scuff and stain resistant coatings. Primers to promote adhesion are available. Films are designed for thermoforming with heat and pressure in the bladder press or vacuum forming process. Decorative effects can be achieved with two-ply films when a router is used to expose a different color in the bottom ply film. Films may also be flat laminated or mitrefolded.

Wrapping Films

Calendared or extruded rigid vinyl films in gauges from 0.005-in. to 0.010-in. Film may be printed in wood grain or decorative patterns. Films may be embossed and may be coated with scratch and stain resistant coatings and primed to promote adhesion. Films are designed for wrapping profiles and can also be flat laminated and mitre-folded.
COPYRIGHT 1992 Vance Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:Laminating User's Guide
Publication:Wood & Wood Products
Date:Jun 1, 1992
Words:2691
Previous Article:LMA expands services to the decorative laminating industry.
Next Article:Voluntary standard for decorative foil overlay.
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