HK1021161A - Laminated sheet and process for manufacture of a laminated sheet - Google Patents

Description

Laminate sheet and method of manufacturing laminate sheet

The present invention relates to a laminate sheet and a method of manufacturing the laminate sheet.

In particular, the present invention relates to a laminate comprising a metal foil and paper and a method of manufacturing the laminate.

Laminated sheets, such as those made from metal foil and paper sheets, can be used in a variety of applications, including wrapping or wrapping paper. Consumer products, such as candy, are often packaged individually or in packets, while cigarettes or cigars are often sold as tins or boxes lined with the laminate. The laminate is particularly suitable for use as a liner because the metal foil forms a barrier against light and moisture which are harmful to tobacco.

The laminate is often printed or embossed with a design, such as a trademark, logo or company name of the manufacturer or distributor, or other information to enhance the presentation of the goods packaged or wrapped with the laminate.

Typically, the pattern is printed or embossed on only one side of the laminate. Typically, one side of the paper is printed or one side of the metal foil is embossed, but occasionally one side of the metal foil is printed or embossed on the paper. Printing or embossing is carried out by methods well known in the art of printing, such as roll-to-roll embossing and gravure printing.

Although it is well known in the printing and paper industry to produce laminates comprising embossed metal foil and printed paper, no one has so far provided a laminate on which the printed and embossed patterns are in registration, i.e. on which the printed and embossed patterns are exactly in register.

It is an object of the present invention to provide a laminate comprising printed paper and embossed metal foil, wherein the printed and embossed patterns are in registration.

It is still another object of the present invention to provide a method of manufacturing the laminate sheet.

The method of manufacturing a laminate sheet of the present invention comprises the steps of:

(i) sticking the metal foil and the paper sheet together;

(ii) printing a pattern on the outer surface of the paper; and

(iii) a mirror image is embossed on the foil in registration with the pattern printed on the paper.

The method of manufacturing a laminate sheet of the present invention comprises the steps of:

(i) sticking the metal foil and the paper sheet together;

(ii) imprinting a pattern on the metal foil; and

(iii) a mirror image is printed on the outer surface of the paper in registration with the pattern imprinted on the foil.

As previously indicated, the order of the printing and embossing steps is not important. However, the embossing step is preferably done before the printing step.

The method particularly preferably includes inspecting the first formed print or imprint pattern and controlling the subsequent imprint/printing steps to ensure registration of the subsequently formed print and imprint pattern with the original pattern.

The step of adhering the paper sheet and the metal foil sheet together may be accomplished by any suitable method. In a preferred embodiment, the metal foil is passed through an applicator roll which applies adhesive to one side of the metal foil. The paper and foil are then passed between a nip of a pair of rollers and the adhesive coated surfaces of the paper and foil are pressed together to form a laminate.

The embossing step may be accomplished using any suitable method. In one method of imprinting, a workpiece (e.g., a roll) and an imprint mold are placed on both sides of a laminate and assembled together, with the mold contacting the metal foil and imprinting a pattern thereon. In another method of stamping, the workpiece is stationary and the stamping die is moved up and down against the metal foil of the laminate. In another method of stamping, the workpiece is moved against a sheet of paper in a laminate, and a metal foil is pressed onto the stamping die.

The embossing step preferably comprises feeding the laminate between a nip of two rolls, one roll serving as a workpiece and being made of a relatively soft material, such as paper, and the other roll serving as a stamp and being made of a metal, such as steel.

The printing step may be accomplished by any suitable method. For example, the printing step may include raised or flapper printing, lithographic printing or gravure printing, such as photographic gravure or roll-to-roll printing.

The laminate of the present invention may have physical properties suitable for the intended use. For example, for purposes of candy packaging, the flexibility of the laminate needs to be good. For the purpose of a liner for a cigarette pack, the laminate needs to be relatively stiff so that it can be folded and held in that folded condition.

By selecting the grade and type of adhesive and paper and/or metal foil, different physical properties of the laminate may be provided in part.

The metal foil preferably comprises a metal selected from the main group of the periodic table of the elements.

The metal foil particularly preferably comprises or consists of aluminum.

The method of the invention may comprise dyeing the metal foil. The dyeing step preferably comprises a roll gravure process. The metal foil is colored over its entire surface by passing it over a gravure roll which is coated with ink. The coloring ink that is roll-coated on the metal foil by the gravure is dried by passing the metal foil through a hot air chamber or the like.

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is a schematic diagram of a preferred embodiment of the process of the present invention by which preferred laminates of the present invention can be made;

FIG. 2(a) is a plan view of the metal foil surface of the laminate sheet manufactured according to the method shown in FIG. 1;

FIG. 2(b) is a plan view of the paper side of a laminate sheet made according to the method shown in FIG. 1;

fig. 3 is a cross-sectional view of the laminate sheet shown in fig. 2(a) and 2 (b).

In the method shown in fig. 1, the foil 3 and paper 4 are fed from respective cylinders 1 and 2 through a series of stations where the foil 3 and paper 4 are laminated together, the paper 4 is printed with a pattern and the foil 3 is printed with a mirror image.

Referring to fig. 1, a metal foil 3, typically a silver-aluminum alloy foil, passes from a roll 1 through an applicator roll 5 which applies adhesive to one surface of the metal foil 3, preferably forming a uniform adhesive film.

Then, the metal foil 3 is passed between two laminating rollers (6a, 6b) together with the paper 4 coming off the roll 2, and the adhesive-coated surface of the metal foil 3 and one surface of the paper 4 are uniformly pressed together to form a laminated sheet.

The laminate is then brought into contact with a gravure roller 7 and the roller 7 deposits a layer of colouring ink on the outer surface of the metal foil 3, thereby colouring the outer surface of the metal foil 3 of the laminate.

The laminate is passed through a drying chamber 8 in which hot air is circulated to dry the wet ink.

The laminate is then passed over a gravure cylinder 9 which prints a pattern on the outer surface of the paper 4.

The laminate is passed through a further drying chamber 10 to dry the wet ink on the paper.

The laminate then enters an embossing station comprising a work piece 12a and an embossing die 12b, which embossing die 12b embosses a mirror image of the pattern printed on the paper 4 on the metal foil 3. A controller including a sensor 11 is provided upstream of the stamping station for detecting the pattern printed on the paper 4 and controlling the stamping process in any suitable manner to ensure that the mirror image stamped on the foil 3 is in register with the pattern printed on the paper 14.

Finally, the embossed and printed laminate is wound onto a large roll 13 for storage, ready to be cut and rolled onto a smaller roll.

Fig. 2a shows the outer surface of a metal foil 3 of a laminate segment manufactured as described above, on which a pattern 15 is embossed, comprising an arrangement of the word "tobaco". Fig. 2b shows the outer surface of the paper 4 of the laminate segment shown in fig. 2 a. The outer surface of the paper is marked with a printed pattern 17 comprising an array of words "tobaco". The arrangement is such that the shape, size and position of the embossed and printed pattern correspond.

Fig. 3a is an enlarged cross-sectional view of the laminate fragment shown in fig. 2a and 2b, showing the foil 3 and the paper 4 adhered together by a thin layer of adhesive 18. The foil 3 is provided with an imprint 19 where an imprint die contacts and presses against the foil surface. Since the embossing and printing patterns are in register, the paper is deposited with ink 20 which corresponds to the imprint 19 on the foil 3.

Fig. 3b is an enlarged cross-sectional view of the laminate fragment shown in fig. 2a and 2b, showing the foil 3 and paper 4 adhered together by a thin layer of adhesive 18. The metal foil 3 is provided with an imprint 14 where the stamp does not contact and press against the metal foil surface. Since the embossing and printing patterns are in register, the paper is deposited with ink 16 which corresponds to the imprint 14 on the foil 3.

It should be noted that the particular pattern shown in fig. 2a and 2b is optional and that any suitable pattern may be embossed and printed on the laminate.

It should also be noted that laminates having embossed and printed registered mirror images are believed to be an important method for purchasers of e.g. tobacco based goods to distinguish between different merchant products. In the tobacco industry, major profits are based on being able to distinguish counterfeit cigarettes.

While the invention has been described in terms of its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification.

Claims (8)

1. A method of making a laminate sheet comprising the steps of:

(I) sticking the metal foil and the paper sheet together;

(ii) printing a pattern on the outer surface of the paper; and

(iii) a mirror image is embossed on the foil in registration with the pattern printed on the paper.

2. A method of making a laminate sheet comprising the steps of:

(I) sticking the metal foil and the paper sheet together;

(ii) stamping a pattern on the metal foil; and

(iii) a mirror image is printed on the outer surface of the paper in register with the pattern imprinted on the foil.

3. A method as claimed in claim 1 or 2, comprising detecting the first formed print and imprint pattern and controlling the subsequent imprint/printing steps to ensure that the subsequently formed print and imprint pattern is in register with the original pattern.

4. A method as claimed in any preceding claim, wherein step (i) comprises contacting the metal foil with an applicator roll which applies adhesive to one surface of the metal foil and passing the adhesive-coated metal foil together with the sheet through a gap between a pair of rolls to compress the sheet together with the adhesive-coated metal foil to form the laminate.

5. A method according to any preceding claim, wherein the metal foil comprises a metal selected from the main group of the periodic table.

6. The method of claim 5, wherein the metal foil comprises or consists of aluminum.

7. A method as claimed in any preceding claim, which includes dyeing the metal foil.

8. A laminate produced according to the method of any preceding claim.