Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B44—DECORATIVE ARTS
  • B44C—PRODUCING DECORATIVE EFFECTS; MOSAICS; TARSIA WORK; PAPERHANGING
  • B44C1/00—Processes, not specifically provided for elsewhere, for producing decorative surface effects
  • B44C1/16—Processes, not specifically provided for elsewhere, for producing decorative surface effects for applying transfer pictures or the like
  • B44C1/165—Processes, not specifically provided for elsewhere, for producing decorative surface effects for applying transfer pictures or the like for decalcomanias; sheet material therefor
  • B44C1/17—Dry transfer
  • B44C1/1712—Decalcomanias applied under heat and pressure, e.g. provided with a heat activable adhesive
  • B44C1/1716—Decalcomanias provided with a particular decorative layer, e.g. specially adapted to allow the formation of a metallic or dyestuff layer on a substrate unsuitable for direct deposition
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B44—DECORATIVE ARTS
  • B44C—PRODUCING DECORATIVE EFFECTS; MOSAICS; TARSIA WORK; PAPERHANGING
  • B44C1/00—Processes, not specifically provided for elsewhere, for producing decorative surface effects
  • B44C1/10—Applying flat materials, e.g. leaflets, pieces of fabrics
  • B44C1/14—Metallic leaves or foils, e.g. gold leaf
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/0427—Coating with only one layer of a composition containing a polymer binder
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2439/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Derivatives of such polymers

Definitions

• the metallisation process can be carried out after having applied on specific areas a detaching resin which, at the end of the process, is removed thus obtaining the partially metallised film (JP 59109529; AN 1984-
• Another common method consists in the use of shaped templates which, by blocking the passage of the metal during the process of metallisation under vacuum, limit the deposition of the metal onto the areas of interest.
• a system used to date for this aim consists in the zonal printing of a metallised film with materials resistant to chemical attack, and in the successive removal of the metal from the non protected areas by treatment with aqueous solutions containing acids or alkalis.
• the process when carried out at high speed, does not guarantee the homogeneity of the product; in addition the process requires the heating of the washing solution to a temperature of 60-100°C in order to allow to reduce the concentration of chemical agents (for example NaOH) and, at the same time, to maintain the same solubilising capacity.
• chemical agents for example NaOH
• the process provides the use of inks resistant to the aggressive chemicals, in particular inks containing pigments with such characteristics; the use of these inks consequently limits graphic possibilities and the achievable tonalities.
• the process requires particular attention during the washing step to protect both the various parts of the machine from the chemical agents and the individuals carrying out the process; in addition careful disposal of the chemical agents is required after neutralisation .
• the invention relates to a process for the preparation of partially metallised and printed plastic film and to the monofilm and coupled wrappers obtained from it.
• plastic films usable in the present invention comprise polypropylene, bioriented, co-extruded or lacquered polypropylene, polyesters and polyamides, preferably polypropylene and more preferably lacquered polypropylene.
• the process comprises the following steps:
• A) a hydrosoluble varnish is applied over the whole surface of a plastic film using a rotogravure printing machine;
• the film is metallised under vacuum, depositing a thin layer of aluminium over the whole surface of the varnished side of the film;
• the metallised film is printed with water-resistant inks using the rotogravure machine;
• the process of the present invention allows to obtain printed wrappers having the characteristic of bearing a metallic layer under the inks and, at the same time, transparent areas which allow the viewing of the contents of the package.
• the printed areas have particularly brilliant colours and exceptional metallic appearance, producing therefore graphics of a qualitative level never achieved with similar techniques known to date.
• the hydrosoluble varnish used in step A) is preferably a varnish containing polyvinylpyrrolidone in an alcoholic solvent, having a dry residue comprised between 32 and 36 % and a viscosity comprised between 52" and 58" (#4 Ford cup).
• the alcoholic solvent can be methanol, ethanol or isopropanol, preferably ethanol.
• the varnish is adjusted to the viscosity necessary for the printing process by dilution with a low molecular weight alcohol such as methanol, ethanol or isopropanol, preferably ethanol.
• the viscosity of the diluted product can vary between 14" and 22" (#4 Ford cup), preferably between 16" and 20", in particular between 17" and 19".
• the varnish is applied at a machine speed comprised between 100 and 150 metres/minute and with a drying temperature comprised between 80 and 110°C;
• the application takes place, preferably, at a speed comprised between 120 and
• the amount of varnish deposited onto the film can vary between 0.5 and 2.0 g/m 2 , preferably between 0.5 and 1.4 g/m 2 , more preferably between 0.5 and 1.1 g/m 2 .
• a particularly preferred subject of the present invention is hence the process according to steps A), B),C) and D) applied onto lacquered polypropylene film as well as the simple or coupled film thus obtained.
• the metallising process of step B) can be carried out according to the known plastic film metallising processes so as to obtain a metallic layer having optical density comprised between 1.2 and 2.0, preferably between 1.4 and 1.8 (Theimer Type DDM 4).
• the inks used in step C) are nitrocellulosic type, inks for rotoflexographic use suited to the printing of metallised films without the use of primers and having high resistance to water; the inks can be added to by antiscouring or antiscratch additives to improve their resistance during the washing process.
• the inks have a dry residue varying between 30 and 60 % according to the pigment bases used and are dilutable with ethyl acetate or mixtures of ethyl acetate and ethyl alcohol.
• the amount of ink applied onto the metallised film can vary from 1.5 to 4.5 g/m 2 depending on the graphic to be realised.
• the washing with water of step D) is carried out in a special machine which allows the removal of the hydrosoluble varnish and the metal deposited on it from the areas not protected by the inks; the washing process can be carried out at a speed comprised between 80 and 150 metres/minute and the drying of the washed film at a temperature comprised between 80 and 120 °C.
• the washing is preferably carried out at a speed comprised between 100 and 130 metres/minute and with a drying temperature comprised between 90 and 110 °C.
• the film thus obtained can be used as it is as wrapper for containers, for example such as external wrapper for food containers, or as it is as wrapper in direct contact with food; or can be used following coupling with one or more plastic films.
• the coupling can be carried out both through the known technologies using solvent based adhesives and through the known technologies based on solvent free adhesives.
• the single film or the coupled wrapper can then be subjected to further treatments used in the packaging sector, such as, for example, the application of welding lacquers or "release” varnishes.
• plastic films which can be used for coupling with partially metallised and printed films are polypropylene, bioriented, co-extruded or lacquered polypropylene, polyester and polyethylene, preferably co-extruded or lacquered polypropylene and polyethylene.
• the varnish is applied after dilution with ethyl alcohol so as to obtain a viscosity of 18" (#4 Ford cup).
• the varnish is applied with a drying temperature varying between 95 and 105 °C so as to deposit onto the film a quantity of 1.0 gram per square meter of surface area.
• the film is then dried at a temperature varying between 90 and 110 °C.
• the plastic film thus obtained has an area printed with a design covering approx. 30% of the surface of the film.
• the inks are particularly brilliant and have a pronounced metallic appearance due to the presence of the underlying thin layer of aluminium.
• the remaining non-printed area of the film is perfectly transparent without any trace of the metal previously deposited.
• the light transmission of the film (Haze 1.2% - ASTM D 1003) is substantially equivalent to the light transmission of the film prior to the process (Haze 1.0 % - ASTM D1003). This indicates that the process, despite the use of ethyl alcohol, is carried out in such a manner so as not to damage the lacquered surface of the original film.
• a coextruded polypropylene film with a thickness of 30 microns is subjected to the process as described in Example 1.

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• 2002
  • 2002-05-28 IT IT2002MI001150A patent/ITMI20021150A1/it unknown
• 2003
  • 2003-05-27 EP EP03755141A patent/EP1509406A1/de not_active Withdrawn
  • 2003-05-27 WO PCT/EP2003/005553 patent/WO2003099586A1/en not_active Application Discontinuation
  • 2003-05-27 AU AU2003242582A patent/AU2003242582A1/en not_active Abandoned

Non-Patent Citations (1)

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