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What means "profile-wrapping"?

​Profile wrapping is a process by which a decorative surface is laminated onto a substrate in lineal form. This is done by means of a profile-wrapping machine.

 

  • Why was the process invented?

    Several decades before a decorative surface was manually laminated, mainly wood veneer, onto a substrate. The increasing demand for furniture at the beginning of the sixties was the release to invent a profile-wrapping machine.
    Beyond that the pressure at costs and prices as well as the requirements of the customers regarding the surface design played a substantial role.
    One of the first was build by Mr. Reinhard Düspohl.
     

  • Which industry use the technology?
    • Derived timber product-working industry
    • Wood-working industry
    • Wood composite materials-working industry
    • Plastics industry
    • Metal-working industry
       
  • Which substrate can be laminated?

    HOLZWERKSTOFFE

    • Particle board
    • Medium density fibre- board (MDF)
    • High density fibreboard (HDF)
    • Plywood
       

    SOLID WOOD

    WOOD COMPOSITE MATERIALS

    • "Extruded wood" (plastics+sawdust)


    PLASTICS

    • PVC (polyvinyl chloride)
    • PP (polypropylene)
    • ABS (acrylonitrile-butadiene-styrene)
    • Expanded polystyrene
    • and others
       

    METAL

    • Aluminum
    • Steel
    • Others
       
  • What are typical wrapping or overlay materials?

    Wood veneer
    The wood veneers are devided into two major groups: Rotary cut veneer and sliced veneer. Sliced veneer is the most common used veneer in profile wrapping. The complexity of the core material dictates the quality of veneer to be used.
    Fleece backed veneer one manufactures, as a fleece is glued on the back of the veneer. The veneer becomes more flexible by the glued on fleece.

    The quality of symmetric and asymmetric finger jointed veneer is visible after the lacquering process. In case of a low quality two different pigmentations are visible. It is possible to avoid different pigmentations by using veneer with an aluminium indicator.
    Veneer with an aluminium indicator is always in roll form. At the joint between the veneer sheets an aluminium strip is applied. This type of veneer needs to be ordered with a specified sheet lenght within the roll of veneer. The sheet lenght needs to be 1“ longer then the profile it will be applied to allowing some lenght variations in the substrate. The advantage of the aluminium indicator is, that there is no finger joint on the substrate. This is accomplished by using sensors on the machine to pick up the position of the aluminium indicator at the joint. The signal is used to for positioning the substrate to the aluminium indicator in the veneer roll. In the aforementioned way it is guaranteed that the beginning of the veneer sheet is synchronous with the beginning of the substrate.

    Paper
    Different paper types are available for profile wrapping. Paper for profile wrapping is usually constructed like a sandwich. It starts out with the base paper that is also referred to as the backer. The backer is available in different colours and different weights. The second item is a décor paper. The décor paper can be solid colour or with a printed pattern. The décor paper is usually a 30 gram paper. This décor paper is laminated to the base paper. The colour of the finished paper is dependent on the colour of the base paper. These papers can range from 30 grams to 300 grams and more. Most commonly used papers are 60 or 80 gram papers. They can be wrapped around very complex profiles and at the same time they are not as fragile as a 30 gram paper. Paper can be wrapped around sharp edges (with exception of very heavy papers).

    Laminates
    Laminates consists of decorative surface papers, which are impregnated with melamine resins and then pressed over Kraft paper core sheets impregnated with phenolic resin. These sheets are then bonded at pressures greater than 200 Kg per square cm at temperatures approaching 150 degrees celsius. Finished sheets are trimmed, and the backs sanded to facilitate bonding. Laminates are more difficult to wrap in comparison with wrapping paper, because papers are more flexible. The variety of laminates ranges from high-pressure to low-pressure to continuous laminates. There is a difference in the way theses laminates are manufactured as well as in the flexibility of the material. Sharp edges are not recommended. For the flooring industry the laminates are coated with aluminium oxide.
    In case of profile-wrapping with laminates an extrem long wrapping zone is necessary. The temperature of the laminate must amount to, if corners are to be wrapped, in the appropriate places 300 ° C.

    Vinyl (Films)
    There are many different types of vinyl available. The most commonly used materials are hard / soft PVC and PP. Vinyl can be a solid colour or have a printed pattern. Different topcoats are available for interior or exterior products.
    Interior
    No special requirements.
    Exterior
    The vinyl has to be durable against ultraviolet jets . A special vinyl with a wood-similar surface (veneer characteristics) and aluminium similar surface (aluminium characteristics) is available for exterior application, which is mainly used by the plastic window industry.
    The newest development is a thermoplastic film for the decorative finishing of windows, doors and other building elements. The film is suitable for climatically difficult regions too, because of a higher weather and temperature stability. Also under difficult conditions the foil is characterised by an outstanding colour and gloss stability. Before the glue application the processing temperature of “Renolit-Fast“ has to be 80 ° C with less tolerance.
     

  • What are the usually-used adhesive types for wrapping?

    Hot melt glue
    Today hot melt glue is the most common glue used in the profile wrapping industry. Main advantages in comparison with other glue types are: High combination potentialities in the materials, higher transportspeed of the profile wrapping machine possible.
    The difference between filled and unfilled hot melt glue is not visible. Only the weight is differencing. Filled glue is heavier than water. We don't recommend filled glue for a slot coater.
    The difference between “not humidity-reactivily“ and “humidity-reactivily“ adhesive is, that humidity-reactivily hot melt glue is received during the interlacing a chemical compound (isocyanates) with the humidity from the air. After the interlacing is finished (circa 3-5 days) it is impossible to re-activate and/or to liquefy the glue. The developed adhesive compounds are characterised by extreme temperature and water resistance.

    Not humidity-reactivily glue:

    • EVA (Ethylen-Vinyl-Acetat)
      By the abbreviation EVA you understand a copolymer, which is made of ethyls and vinyl acetat; Since over 30 years the basis polymer for hot melt glues. The cost/performance ratio of EVA is good. Disadvantages of this product group are: The limited resistance to heat (Re-activate temperature: 80 ° C – 100 ° C) and humidity (no exterior use).

     

    • APAO (Amorphes-Poly-Alpha-Olefin), abbreviation PO (Polyolefine)
      Under this name several terms hide themselves: polyethylene(PE), polypropylene (PP), polybutylene (PB) et al., For the adhesive production these pure polyolefines are only little suitable. From larger interest are the amorphous polyolefines manufactured in a special procedure as well as their co- and terpolymere, which is then brought into the market under the comprehensive term amorphes-poly-alpha-olefin (APAO) or short polyolefine (PO). The main advantage in comparison with EVA is the higher heat resistance (re-activate temperature 110 ° C – 130 ° C). PO is not suitable for exterior applications. Due to a high temperature resistance and with it connected a high melting energy demand reduce the capacities of all available melting aggregates over up to 50 %.


    Humidity-reactivily glue:

    • PUR (Poly-Urethan-Reaktiv)
      The abbreviation PUR stands for single component, humidit- reactive polyurethan hotmelts. The glue type PUR fulfills highest requirements regarding temperature-, water-, steam -, detergent- and solvent-resistance. The main advantages compared with EVA and PO are: High heat and water resistance. PUR adhesives are suitable for interior and exterior use without exception (all materials). PUR glue is offered in block (blocks with 2 Kg - 18 Kg weight) and barrel form with 200 Kg/barrel. One producer offers PUR-granulate too. The glue in block form has a smaller surface compared with granulate, which reduce the danger of humidity interlacing. Due to the comparatively low working temperature PUR is most suitable for thin themoplastic films.
       
    • APAO-R (Amorphes-Poly-Alpha-Olefin-Reaktiv)
      More details regarding the abbreviation-part APAO see APAO. The addition R means reactiv. The APAO-R glue is on polyolefine basis with reactive characteristics (see PUR). The adhesive is suitable for interior and exterior use and is offered in block form. The APAO-R glue is used more rarely.
       
    • Water based glue
      PVA, PVAc, ...,
      The water based glue, the portion water can amount to up to 50 %, has some disadvantages compared with hotmelt glue. In production the energy consumption is very high and the production speed very low, because the water portion must be evaporated. You have reduced possibilities in wrapping (only suitable for substrates with less profile).
       
    • Solvent based glue
      Polyurethane, ...,
      Due to new emission-protection-acts it is not recommended to invest in a machine/line, which runs with solvent based glue.

  • How can the quantity of adhesive, which is needed in production, be calculated?

    Formula:
    Width of overlay material in m X Transport speed in m/min X 60 Minuten X Grammage per qm in Kg/qm = Mass of glue in Kg/h.

    Example:
    Overlay material 250 mm = 0,25 m X 40 m/min X 60 minutes X 50g/qm = 0,05 Kg/qm = 30 Kg/h.

    If one want to use more than ⅔ of the capacity of our melting units, we recommend to make tests in our operation. The melting capacity varies dependent on glue type and manufacturer.
     

  • Some profile wrapped endproducts.

    The following endproducts may be made of the listed materials combinations. Please keep in mind, that the table below reflects only a fraction of material combinations. Other combinations are possible.

    The decision, which adhesive should be used, depends also on the temperature influences on the route of transportation of the wrapped endproduct. Therefore the material combination specified before can change.
    Substrates that are not made from derived timber products, plywood, wood or extruded wood (non-wood substrates) may require some treatment prior to wrapping. In any case the selected glue manufacturer should be consulted for a recommended treatment.

Plastic substrates

For example extruded PVC, contain a substance, that will migrate to the surface of the substrate over time. Extruded PVC substrates also pick up some lubricants that are used in the extruder. Because of the before mentioned reasons, the substrates should be primered ere it gets wrapped. The primer can be applicated with felt pads (non flammable primer !) or by using the new primer application system (aqueous primer). PrimeStar 2010 to apply primer is an innovation by düspohl. For more than 25 years there was no genuine innovation in the area of primer application on plastics and metals. In order to ensure a optimal adhesion the tension of the surface, which should to be wrapped is changed and the surface is cleaned by the primer.

Metal

Substrates can arrode after the wrapping process. The corrosion can destroy the glue line, which leads to the fact, that the gluing and/or the overlay material becomes detached. To avoid corrosion, you can use a treated metal for wrapping (painted, powder coated, chromed, … ). An other solution, in case you work with raw and degreased metals, is the application of primer or the combination of a treatment in the plasma or corona method and primer.