METHOD FOR MANUFACTURING A METALLIZED PAPER MATERIAL

Abstract: A method for manufacturing a metallized paper material, comprising the steps of: providing a paper material having a wax or lubricant; coating one side of the piece of paper material with a metal; contacting one side of said piece of paper material with the other side of another piece of paper material of the same type, or with the other side of another part of the same piece of paper material; keeping said faces in contact with each other so as to form a slip layer by migration of the wax or lubricant onto the metal coating; separating the pieces or parts of paper material from each other.

Description: Method for manufacturing a metallized paper material The invention is related to the field of manufacturing metallized papers, in particular for packaging purposes. A typical application is in the packaging of cigarettes as an inner liner or internal wrapping, to ensure against loss of flavour and against the drying of the cigarettes. Both are critical parameters for the manufacturer and the end user, and provide confidence in the quality of the end product. Other applications of the metallized paper material include decorative papers or gift wrap. The metallized paper material in question can consist of a paper to which by vapour deposition is applied an aluminium layer, for instance with a substance of 20 grammes per square metre. However, this material appears to have several disadvantages. The metallic coating is applied by vaporisation and is subsequently coated with a lacquer or varnish. The purpose of this coating is to protect the metal from being abraded. For instance, by a process such as imprinting or embossing and folding the metallic coating, if exposed, would flake or peel off leading to metal particles being deposited on the machines used in the manufacturing process. As a result, the machines could become damaged and the production efficiency could be affected. The coating of lacquer or varnish has the further positive effect of reducing the friction between the surfaces of paper and machinery, and between superposed sheets of papers. This effect is to be attributed to the chemicals such as waxes and starches in the lacquer or varnish. The application of such lacquer or varnish coating however represents an additional manufacturing step, implying additional costs in raw materials and processing time. A method of this kind is known from DE-C-4412019. The object of the invention is to provide such method which does not have these disadvantages. This object is achieved through a method for manufacturing a metallized paper material, comprising the steps of: -providing a piece of paper material having a wax or lubricant, -coating one side of a piece of paper material with a metal, -contacting one of the sides of said piece of paper material with the other side of another piece of paper material of the same type, or with the other side of another part of the same piece of paper material, -keeping said faces in contact with each other so as to form a slip layer by migration of the wax or lubricant coating onto the metal coating, -separating the pieces or parts of paper material from each other. The wax or lubricant may be brought into the piece of paper material during the process of manufacturing said material. A preferred embodiment of the method according to the invention, wherein the piece of paper material is a paper web, comprises the step of reeling the web onto a reel after coating said web with a metal layer, such that the one side of each winding of the web is in contact with the other side of a next winding. This method ensures that in a simple and reliable way, a continuous, coherent slip layer may be formed on the aluminium coating. The wax or lubricant migrates from the piece of paper material towards and onto the adjoining metal coating of the next winding. Thus, in no part of the metal coating friction forces will develop which would be so high that thereby flaking of the metal coating is generated. Good results are obtained in case the contacting sides of the paper material are kept in contact for at least 2 hours. Preferably, the relative humidity is less than 552- The method according to the invention can be carried out with several waxes, including low molecular weight paraffins, polyethylene waxes, polypropylene waxes modified with maleic anhydride, ester and acid waxes, amide waxes, natural waxes, fatty acids, their esters and alcohols, and sulphonate waxes. The fatty acid esters may include short or long chain monovalent alcohols, glycol fatty acid esters, glycerine fatty acid esters and crystalline micro waxes of polyethylene. The step of coating the metal layer may include vacuum precipitation, cathodic spraying, vapour phase plating, current free plating, electro plating, vaporisation or absorption. The metal coating comprises gold, silver, copper, aluminium or mixtures thereof. Reference is made to the aluminium foil laminate as known from US-A-335 3^8, which comprises a paper substrate coated with wax blends. The aluminium layer is protected here by a shellac or a nitrocellulose wash coat. This coat should protect the aluminium against possible transfer of the wax blends from the paper onto the aluminium layer, once the sheet in question is stored in rolls. According to the invention, this transfer process however is usefully applied for the formation of a slip layer onto the metallic surface.

Claims: C l a i m s 1. Method for manufacturing a metallized paper material, comprising the steps of: -providing a piece of paper material having a wax or lubricant, -coating one side of the piece of paper material with a metal, -contacting one side of said piece of paper material with the other side of another piece of paper material of the same type, or with the other side of another part of the same piece of paper material, -keeping said faces in contact with each other so as to form a slip layer by migration of the wax or lubricant onto the metal coating, -separating the pieces or parts of paper material from each other. 2. Method according to claim 1, wherein the piece of paper material is a paper web, and comprising the step of reeling the web onto a reel after coating said web with a metal layer, such that the one side of each winding of the web is in contact with the other side of a next winding. 3. Method according to claim 1 , wherein the piece of paper material is a board. 4. Method according to one of the preceding claims, wherein the contacting sides of the paper material are kept in contact for at least 24 hours. 5« Method according to any of the preceding claims, wherein the relative humidity is less than 55#- 6. Method according to any of the preceding claims, wherein the wax includes low molecular weight paraffins, polyethylene waxes, polypropylene waxes modified with maleic anhydride, ester and acid waxes, amide waxes, natural waxes, fatty acids, there esters and alcohols, and sulphonate waxes. 7. Method according to claim 6, wherein the fatty acid esters include short or long chain monovalent alcohols, glycol fatty acid esters, glycerine fatty acid esters and crystalline micro waxes of polyethylene. 8. Method according to any of the preceding claims, wherein the metal coating step includes vacuum precipitation, cathodic spraying, vapour phase plating, current free plating, electro plating, vaporisation or absorption. 9. Method according to any of the preceding claims, wherein the metal coating comprises gold, silver, copper, aluminium or mixtures thereof. 10. Method according to any of the preceding claims, wherein before applying the metal coating, a pre-metallization coating or primer is applied to the paper material.

Inventors: AINSCOUGH ANTHONY NORBERT, AINSCOUGH, ANTHONY, NORBERT
Applicants: AINSCOUGH ANTHONY NORBERT, LEER KONINKLIJKE EMBALLAGE, AINSCOUGH, ANTHONY, NORBERT, KONINKLIJKE EMBALLAGE INDUSTRIE VAN LEER N.V.
Application year: 1997
Main classification: D21H23
IPC codes: D21H19, D21H23