EP0670386B1 - Sheet, especially for wrapping greasy products, and processes for making the same - Google Patents

Abstract

The greaseproof paper, especially for wrapping (1) fatty foodstuffs, is damp resistant paper (2) as a barrier fr ft permeation. One layered surface of the paper is cladded with a layer (4) containing metal, at least in one zone. Also claimed is a mfg, process where the greaseproof paper is coated, followed by a metal layer applied to the coating.

Description

The present invention relates to a sheet intended in particular for the packaging of fatty products, in particular to the packaging of fatty food products, of the type comprising a sheet of paper resistant to humidity and forming a barrier to grease.

We currently know packaging sheets of this type which can be used to package fatty food products like butter and presenting necessary mechanical and aesthetic characteristics the packaging of such products. A leaf commonly used consists of a sheet of parchment paper with, glued on to a solid surface thanks to a thin layer of wax, aluminum foil.

Document AU-D-24168/67 describes a paper packaging formed by a strip of "crystal paper" on one side of which a first layer is applied white base ink covered with a second metallic colored ink layer.

GB-A-2.053.283 describes a paper packaging made of a "paper substrate" made natural or synthetic particles. One of the faces paper is covered with organic resin made up of polymers and a metallic layer.

Such packaging sheets have a relatively high cost of production.

The object of the present invention is therefore to provide a sheet intended in particular for packaging products fat, whose production cost is much lower Student.

To this end, the invention as described in claim 1 relates to a sheet intended in particular for packaging, of the aforementioned type, characterized in that one side of the paper sheet is, in at least one region, coated using a conventional papermaking technique with a coating coating based on fine mineral pigments and then covered a layer of a material containing metal.

According to certain embodiments, the invention may have any of the following:

• La couche de matériau contenant du métal est une couche métallique et une couche de vernis de prélaquage est interposée entre le couchage et cette couche métallique.
• La densité surfacique de l'enduit de couchage est comprise entre 10 et 12 g/m² environ, et/ou la densité optique du métal, constituant la couche métallique, est comprise entre 2,8 et 3 environ et/ou la résistance spécifique de la couche métallique est de 1 Ω/cm² environ.
• La feuille comporte sur sa couche métallique une impression comprenant une couche de vernis d'accrochage en contact avec la couche métallique, portant l'encre d'impression et éventuellement recouverte d'une couche de laque de protection.

According to a first embodiment:

• The layer of material containing metal is a metallic layer and a layer of prepainting varnish is interposed between the coating and this metallic layer.
• The surface density of the coating is between 10 and 12 g / m ² approximately, and / or the optical density of the metal, constituting the metal layer, is between 2.8 and 3 approximately and / or the specific resistance of the metal layer is about 1 Ω / cm ² .
• The sheet has on its metallic layer an imprint comprising a layer of bonding varnish in contact with the metallic layer, carrying the printing ink and optionally covered with a layer of protective lacquer.

• La couche de matériau contenant du métal est une couche d'encres métallisées.
• La densité surfacique de l'enduit de couchage est comprise entre 10 et 12 g/m² environ et/ou l'encre métallisée contient 12 % environ de pâte d'aluminium en poids .

According to a second embodiment:

• The layer of metal-containing material is a layer of metallized inks.
• The surface density of the coating coating is between 10 and 12 g / m ² approximately and / or the metallized ink contains approximately 12% of aluminum paste by weight.

According to one or other of the embodiments, moisture resistant and barrier paper grease is parchment paper or greaseproof paper.

The invention also relates to two methods for manufacturing a sheet as defined above.

a) on prend comme papier de base un papier ayant des propriétés de résistance à l'humidité et de barrière aux graisses ;

b) on réalise sur une première face de ce papier un couchage par enduction avec un enduit de couchage ; et

c) on applique une couche d'un matériau contenant du métal sur la face couchée du papier.

According to the invention, the first method comprises the following steps:

a) a paper having moisture resistance and grease barrier properties is taken as the base paper;

b) coating on a first side of this paper by coating with a coating coating; and

c) applying a layer of a material containing metal on the coated side of the paper.

a) on prend comme papier de base un papier couché sur l'une de ses faces ;

b) on applique une couche d'un matériau contenant du métal sur la face couchée du papier ; et

c) on réalise un traitement du papier ainsi obtenu conférant au papier de base des propriétés de résistance à l'humidité et de barrière aux graisses.

Still according to the invention, the second method comprises the following steps:

a) one takes as base paper a paper coated on one of its faces;

b) applying a layer of a material containing metal on the coated side of the paper; and

c) a treatment of the paper thus obtained is carried out, conferring on the base paper properties of resistance to humidity and barrier to grease.

In the second method, said processing can consist of coating the second side of the paper, or by soaking the sheet in a bath.

• suivant l'un ou l'autre des procédés, la métallisation de la face couchée peut être réalisée par un procédé de prélaquage suivi d'une métallisation sous vide,
• l'un ou l'autre des procédés peut comprendre des étapes supplémentaires d'enduction de la face métallisée avec un vernis d'accrochage, d'impression et éventuellement d'enduction avec une laque de protection.
• Dans le cas du deuxième procédé, ces étapes supplémentaires peuvent être réalisées en ligne avec l'étape c) de traitement du papier couché et métallisé.

In the case of metallization of the coated face:

• according to either of the methods, the metallization of the coated face can be carried out by a pre-lacquering process followed by metallization under vacuum,
• either method may include additional steps of coating the metallized face with a bonding varnish, printing and optionally coating with a protective lacquer.
• In the case of the second method, these additional steps can be carried out in line with step c) of processing coated and metallized paper.

When using metallic inks, the application of the layer of metallic inks is produced by a printing technique.

La figure 1 est une vue schématique éclatée, en coupe, d'un premier mode de réalisation d'une feuille d'emballage suivant l'invention portant des impressions;

Les figures 2 à 4 sont des vues éclatées en coupe schématisant le résultat d'étapes successives d'un premier procédé de fabrication de la feuille d'emballage de la figure 1; et

Les figures 5 à 7 sont des vues éclatées en coupe schématisant le résultat d'étapes successives d'un second procédé de fabrication de la feuille d'emballage de la figure 1.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

Figure 1 is an exploded schematic view, in section, of a first embodiment of a packaging sheet according to the invention bearing impressions;

Figures 2 to 4 are exploded sectional views schematically showing the result of successive steps of a first method of manufacturing the packaging sheet of Figure 1; and

FIGS. 5 to 7 are exploded sectional views schematically showing the result of successive steps of a second method of manufacturing the packaging sheet of FIG. 1.

In FIG. 1, the relative thicknesses of the different layers were not respected, to allow a better understanding of the constitution of a packaging sheet according to the invention.

We can see in Figure 1 that the sheet 1 has a strong sheet of paper 2 moisture and forming a barrier to grease. This sheet can, for example, consist of a sheet parchment paper or a sheet of paper said grease-resistant, such as SERLALIT WS 40g paper from the Finnish company FINAPAR.

The sheet of paper 2 has on one of its faces a coating 3 produced according to conventional papermaking techniques. The coating coating applied will advantageously have a surface density of between 10 and 12 g / m ² approximately. As is well known, it is customary to call "coating" the deposition on a raw paper of a layer based on fine mineral pigments. Usually, the coating of the paper is used to give it the gloss, the color and the luster which then make it possible to obtain an excellent printing result. By their compositions and their viscosities, coating plasters differ fundamentally from printing products based on inks.

A layer 3a of prepainting varnish, then a thin layer of aluminum 4 are deposited flat on the coating 3. Layer 4, deposited by a technique of metallization, keeps the sheet thus formed mechanical inertia characteristics during folding and gives it an advantageous visual aspect for sale in department by improving the appearance of the print. Layer 4 also gives the sheet barrier properties with ultraviolet rays favorable to the conservation of packaged materials.

The aluminum or metallic layer 4, having a thickness of approximately 300 to 500 Angstroms (10 ^-10 m), is represented by a single line in FIG. 3. It results from a metallization of the coated and prepainted surface of the sheet of paper 2, and is not thick enough to be assimilated to a thin sheet of metal. Indeed, the thickness is not sufficient to allow the metal to form a sheet having a compact and aggregated structure.

The thickness of the metal layer is such that its optical density is between 2.8 and 3 and its specific resistance is approximately 1Ω / cm ² .

The packaging sheet 1 shown on the Figure 1 has on its metallic layer 3 an impression comprising a layer of bonding varnish 5, flat on the metallic layer 4. On the bonding layer, inks 6a, 6b, 6c, 6d are deposited by zones identified to show the patterns we want to see appear. Each ink layer consists of a different color ink, allowing printing in polychromy.

The different layers of ink are good heard applied successively, according to a process classic print. The representation made of it is schematic to show the successive layers ink, but we understand that in reality, inks of different colors are arranged in contact with each other others, with certain overlaps.

A layer of transparent lacquer 7 in solid color on the inks 6a to 6d protect the printing from possible deterioration by mechanical contact and improves the appearance visual of the packaging sheet thus obtained.

In some cases, of course, according to the invention, be limited to a packaging sheet including only sheet of paper 2, the layer from the coating 3 and the metal layer 4 but does not with no print.

In addition, when printing is performed, the layer 7 is optional.

Figures 2 to 4 illustrate the results partial obtained at the different stages of a first method of manufacturing a packaging sheet according to the invention such as sheet 1 described above.

In Figure 2 is shown a sheet of base paper 12 which is used for processing of this first process. It is a paper with moisture resistance and barrier properties fats.

As indicated above, one can use by example of parchment paper or greaseproof paper like SERLALIT WS 40g paper from the Finnish company FINAPAR.

According to this first method, a coating of the paper on one side of said paper by coating with a coating, for example by a roller coating technique. A layer 13 from of the solid coating on the sheet of paper 12 is the result presented in Figure 2 of this stage of the process.

The sheet of paper 12 with a flat layer sleeping issue 13 then has a surface condition very smooth essential for subsequent metallization of quality.

The next step in the process is to cover this layer 13 resulting from the coating with a layer 13a of pre-lacquer varnish then with a layer of aluminum 14, shown in Figure 4 and from a step of metallization. This metallization could, for example, be carried out under vacuum.

The process can then be completed by the printing steps of depositing the layers 5, 6a to 6d and possibly 7 in FIG. 1.

Figures 5 to 7 illustrate the results partial obtained at the different stages of a second method of manufacturing a packaging sheet according to the invention such as sheet 1 of Figure 1.

In Figure 5 is shown a sheet of conventional coated paper 20 which is used as paper basic for the implementation of this second method. The sheet of coated paper 20 consists of a sheet of paper 22 and a layer 23 of coating plaster.

Coated paper 20, having a surface finish very smooth, is able to receive directly on its lying down a layer 23a of prepainting varnish then a metal layer 24 deposited by metallization, by vacuum example. These operations constitute the stages following of the second manufacturing process, and their result is shown in Figure 6.

The coated sheet of paper thus pre-coated and metallized then undergoes a treatment step conferring to paper 22 moisture resistance properties and barrier to fat.

This processing step, the result of which is shown in Figure 7, may for example consist of soaking the packaging sheet in a container bath agents 25 capable of impregnating the base paper 22 by giving it the desired properties of resistance to moisture and grease barrier.

This processing step can also consist of in a coating of the non-metallized side of the paper with a coating giving the paper the desired properties greasability and resistance to humidity, such as represented in 25a in broken lines in FIG. 7.

The process of FIGS. 5 to 7 can also be completed by the printing steps. In this case, these steps can be performed online with the step of paper processing described above with regard to the figure 7.

As a variant, the metal layer 4 obtained by a metallization technique can be replaced by a layer of metallic inks applied by techniques classic printing. In this case, we can for example use a mixture of inks and aluminum paste; the aluminum paste can then represent around 12% in weight of the mixture. In this case also, we can consider to remove the prepaint layer 3a.

Claims (14)

1. Sheet intended notably for the wrapping (1) of fatty products, in particular for the wrapping of fatty foodstuffs, of the type consisting of a sheet of paper (2) resistant to humidity and forming a barrier from fats. Characterised in that one side of the sheet of paper is, at least in one area, coated according to a standard paper making technique with a film of coating with a base of fine mineral pigments. Then covered with a layer (4) of a material containing metal.
2. Sheet according to claim 1, characterised in that the layer of material containing metal is a metallic layer, and in that a pre-lacquered varnish (3a) is interposed between the coating and this metallic layer.
3. Sheet according to claim 2, characterised in that the density per unit area of the film of coating (3) is between about 10 and 12 g/m², and/or the optical density of the metal forming the metallic layer (4), is between about 2,8 and 3, and/or the specific resistance of the metallic coating is of about 1Ω/cm².
4. Sheet according to claim 2 or 3, characterised in that it has on its metallic coating (4), printing consisting of a layer (5) of bonding varnish in contact with the metallic coating, carrying the printing ink (6a,6b,6c,6d) and possibly covered with a coating of protection lacquer (7).
5. Sheet according to claim 1, characterised in that the layer of material containing metal is a coating of metallic inks.
6. Sheet according to claim 5, characterised in that the density per unit area of the coating film (3) is between about 10 and 12 g/m², and/or the metallic ink contains about 12% aluminium mixture in weight.
7. Sheet according to any of the previous claims, characterised in that the paper (1) resistant to humidity and forming a barrier against fats is of greaseproof paper or of paper said to be greaseproof.
8. Manufacturing process of a sheet according to any of the claims 1 to 7, characterised in that it consists of the following stages:

   a) One takes as base paper a paper (12) having the properties of resistance to humidity and barrier to fats;

   b) One achieves a coating (13) on a first side of this paper by surface application according to a standard paper making technique with a coating film with a base of fine mineral pigments and

   c) One applies a layer of a material containing metal (14) on the coated side of the paper.
9. Manufacturing process of a sheet according to any of the claims 1 to 7, characterised in that it consists of the following stages:

   a) One takes as a base paper a paper (20) coated on the first of its sides;

   b) One applies a layer of a material containing metal on the coated side of this paper; and

   c) One achieves a treatment (25,25a) of the paper thus obtained imparting to the base paper the properties of resistance to humidity and barrier to fats.
10. Process according to the claim 9, characterised in that the said treatment consists of a surface application of the second side of the paper or of soaking the sheet in a bath.
11. Process according to any of the claims 8 to 10 for the manufacture of a sheet according to any of the claims 2 to 4, characterised in that the metallization of the coated side is achieved by a process of pre-lacquering followed by metallization under vacuum.
12. Process according to claim 11, consisting of supplementary stages of surface application of the metallized side with a bonding varnish, printing, and possibly surface application with a protection lacquer.
13. Process according to claims 9 and 12 taken together, characterised in that the said supplementary stages are achieved in-line with the stage (c) of the treatment of coated and metallized paper.
14. Process according to any of the claims 8 to 10, for the manufacture of a sheet according to claim 5 or 6, characterised in that the application of the coating of metallic inks is achieved by a printing technique.

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