PAPER MATERIAL FOR FLUID CONTAINERS HAVING CHARACTERISTICS OF CALIBRATED FRAGILITY AND RIGIDITY AND A BARRIER PROPERTY

Abstract

A paper material, including a base substrate having the following formulation: —a mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight—at least one polymeric substance, between 1% and 10% by weight—at least one inorganic filler, between 10% and 50% by weight—at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight—aluminium salts, between 1% and 30% by weight; where the aluminium salts, the at least one polyol and/or acrylic polymer and/or starch being present in at least one surface of the paper material.

Description

The present invention relates to a paper material, a paper or paperboard produced with said paper material, a method of producing said paper material, and a container for fluid material produced with said paper material.

In the paper industry, there is a constant quest for new types of paper and paperboards for technical use having particular capacities and/or finishes, and above all intended as a barrier against gases and liquids, etc.

Paper-based products obtained with cellulose fibres and/or cotton and/or synthetic fibres, and with synthetic polymer-based and/or petroleum-derived additives, coupled or extruded with petroleum-derived polymers in order to contain and/or protect liquids and/or gels of varying nature, such as cosmetic or food products, have been present on the market for some time.

Such products cannot, however, be coupled with heat-sealable or gluable materials while maintaining the particular characteristics of rigidity and at the same time fragility necessary for a calibrated breakage of the container containing the gel and/or liquid of varying nature.

There is thus a perceived need to produce a paper material that may overcome the limits of the prior art.

The technical task of the present invention, therefore, is to provide a paper material of different grammages which enables the aforementioned technical drawbacks of the prior art to be eliminated.

Within the scope of this technical task, one object of the invention is to provide a paper material of different grammages with intrinsic properties of extreme rigidity, fragility and a capability of being cut with a neat, clean cut.

Another object of the invention is to provide a paper material of different grammages with a capability of being heat-sealable and couplable while maintaining the aforesaid properties of extreme rigidity, fragility and a capability of being cut with a neat, clean cut.

Yet a further object of the invention is to provide a paper material having properties of a barrier to water, fats, oils and gases without prejudicing adequate printability.

Another object of the invention is to provide a paper or paperboard produced with said paper material, a method of producing said paper material, and a container for fluid material produced with said paper material.

The technical task, as well as these and other objects, are achieved according to the present invention by providing a paper material, characterised in that it comprises a base substrate having the following formulation:

• • a mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight
  • at least one polymeric substance, between 1% and 10% by weight
  • at least one inorganic filler, between 10% and 50% by weight
  • at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight
  • aluminium salts, between 1% and 30% by weightsaid aluminium salts and said at least one polyol and/or acrylic polymer and/or starch being present in at least one surface of said paper material.

In the paper material said at least one polymeric substance is adapted to impart to the mixture of fibres mechanical strength and water resistance, said at least one inorganic filler is adapted to impart fragility, whilst the surface treated with at least one polyol and/or acrylic polymer and/or starch in addition to aluminium salts is adapted to impart properties of a barrier and resistance to fats, oils and gases.

Overall, the paper material has mechanical properties of rigidity, fragility and a capability of being cut and processed without losing fibrils of cellulose origin.

The present invention also relates to a container for fluid material characterised in that it has an outer shell made of paper material comprising a base substrate having the following formulation:

• • a mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight
  • at least one polymeric substance, between 1% and 10% by weight
  • at least one inorganic filler, between 10% and 50% by weight
  • at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight
  • aluminium salts, between 1% and 30% by weight said aluminium salts and said at least one polyol and/or acrylic polymer and/or starch being present in at least one outer surface of said outer shell.

The present invention also relates to a method of producing said paper material, characterised in that it comprises the steps of:

• • preparing an aqueous mixture of said cellulose fibres, cotton fibres and synthetic fibres, said at least one polymeric substance, and said at least one inorganic filler;
  • removing water from the mixture to form said base substrate of the paper material;
  • carrying out a treatment of said at least one surface of said base substrate with at least one solution based on said aluminium salts and said at least one polyol and/or acrylic polymer.

Other features of the present invention are defined, moreover, in the subsequent dependent claims, and in the claims related to the manufacturing method and to the device for use.

Additional features and advantages of the invention will become more apparent from the description of a preferred but not exclusive embodiment of the paper material according to the invention, illustrated hereinbelow by way of non-limiting example.

The present invention relates to a velvety paper material (paper/paperboard) which, by virtue of a specially conceived mixture, a specific surface treatment and a production method has an extremely rigid, fragile structure and a capability of being neatly cut, without the typical releases of fibre.

Furthermore, the paper material of the invention is perfectly printable with an adequate print quality and makes it possible to obtain particular graphic effects that are difficult to obtain with traditional filtering paper materials.

In detail, the paper material of the invention comprises a base substrate comprising a mixture of cellulose fibres, cotton fibres and synthetic fibres, at least one polymeric substance, adapted to impart to the mixture of fibres mechanical strength (dry and wet) and water resistance, and at least one inorganic filler, adapted to impart to the material good characteristics of machinability, chemical stability and fragility, and aluminium salts in addition to at least one polyol and/or acrylic polymer and/or starch, adapted to impart a barrier property.

The base substrate has the following formulation:

• • the mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight
  • the at least one polymeric substance, between 1% and 10% by weight
  • the at least one inorganic filler, between 10% and 50% by weight
  • the at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight
  • the aluminium salts, between 1% and 30% by weight said aluminium salts and said at least one polyol and/or acrylic polymer and/or starch being present in at least one outer surface of said outer shell.

The mixture of fibres comprises cellulose fibres and cotton fibres and synthetic fibres in a variable percentage proportion by weight: the length of the cellulose fibres is comprised between 0.2 mm and 5.0 mm; the content of cotton fibres and synthetic fibres in the mixture is in variable proportions of between 1% and 10% by weight.

The cellulose fibres comprise short and long bleached cellulose fibres, raw cellulose fibres and chemi-thermomechanical cellulose fibres in a mixture.

The synthetic fibres can preferably comprise an aliphatic polyolefin.

Preferably, the polymeric substance included in the base substrate comprises one or more resins based on colophony and/or alkyl ketene dimer and/or acetylsuccinic acid and/or epichlorohydrin and/or carboxymethylcellulose.

Preferably, the inorganic filler is a mineral filler comprising one or more substances selected in the group consisting of carbonates, kaolins, talc and mixtures thereof.

Advantageously, the base substrate has at least one surface treated with at least one formula comprising a polyol and/or acrylic polymer and/or starch, in order to impart proprieties of a barrier to water, oils, greases and gases.

The surface treatment is for example an adhesive based on acrylic polymers, complex polyols, or products based on synthetic or natural waxes in order to impart proprieties of a barrier to water, oils, greases and gases.

More in detail, the following formulation was found to be suitable for the base substrate of the paper material:

• • mixture of fibres between 60% and 70% by weight,
  • the at least one polymeric substance, between 2% and 5% by weight
  • the at least one inorganic filler, between 20% and 30% by weight
  • the at least one polyol and/or acrylic polymer and/or starch, between 2% and 5% by weight
  • the aluminium salts, between 1% and 5% by weight

In particular, the following formulation was found to be suitable for the base substrate of the paper material:

• • cellulose fibres 60% by weight
  • cotton fibres 0.2% by weight
  • synthetic fibres 0.5% by weight
  • epichlorohydrin-based resin 2% by weight
  • carboxymethylcellulose-based resin 2% by weight
  • calcium carbonate between 30% by weight
  • aluminium salts 1% by weight
  • styrene-acrylic latex 4% by weight.

The grammage of the paper material according to the present invention is comprised between about 50 g/sqm and 900 sqm.

The above-described paper material is produced in accordance with a further aspect of the present invention, with the following method.

The paper material is produced with a substantially known paper forming technique, for example on a continuous paper-making machine.

An aqueous mixture of cellulose fibres and first- or second-cut cotton fibres and synthetic fibres, containing the polymeric substance (resins based on colophony and/or alkyl ketene dimer and/or acetylsuccinic acid and/or epichlorohydrin and/or carboxymethylcellulose), and the inorganic mineral filler (carbonates, kaolins, talc and mixtures thereof), is prepared.

Subsequently, the water is removed from the mixture in order to form the base substrate of the paper material.

Then follows a step of treating the surface of one or both faces of the base substrate with an aqueous solution, for example composed of an aqueous solution of aluminium salts, polyol, and/or an acrylic adhesive or similar adhesives, in order to lend the necessary barrier property.

The method can subsequently comprise, after the surface treatment with the aqueous solution, a step of smoothing the paper wherein the base paper is smoothed to ISO 2494 Bendtsen smoothness values of less than about 800 ml/min.

The method also comprises a step of mechanically treating the base substrate to obtain a porosity of 1 sec to 50 sec according to the Gurley method.

Finally, the method can comprise a further step of mechanically treating the surface, in particular an embossing step.

Advantageously, a paper material produced in accordance with the present invention can be used to produce a container for fluid material.

In particular, the aforesaid paper material can be used as a replacement for a known plastic material as a substrate externally coupled to a shell for containing the fluid material.

The container for fluid material, be it a liquid or gel, advantageously has a substrate acting as an outer shell produced from the paper material described above.

Advantageously, the formulation that comprises the aluminium salts in addition to the adhesives is present at least in the outer surface of the outer shell.

The outer shell produced from this paper material is configured as a high-rigidity, high-fragility substrate and a barrier to water, oils, fats and gases.

The container thus comprises an inner plastic shell for containing the fluid material, wherein the inner shell is coupled, for example chemically applied, in particular glued or heat-sealed, to the outer shell.

Modifications and variants can be introduced to the paper material and the method for the manufacture thereof according to the present invention and described and illustrated herein without going outside the inventive concept as defined in the appended claims.

Claims

1. A container for fluid material, including an outer shell made of paper material comprising a base substrate having the following formulation: a mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight;at least one polymeric substance, between 1% and 10% by weight;at least one inorganic filler, between 10% and 50% by weight;at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight;aluminum salts, between 1% and 30% by weight;

2. The container for fluid material according to claim 1, wherein a length of the cellulose fibres is comprised between 0.2 mm and 5.0 mm.

3. The container for fluid material according to claim 1, wherein, in the mixture of fibres, a content of cotton fibres and synthetic fibres is in proportion, varying between 1% and 10% by weight.

4. The container for fluid material according to claim 1, wherein said at least one polymeric substance comprises one or more resins based on colophony, alkyl ketene dimer, acetylsuccinic acid, or epichlorohydrin carboxymethylcellulose.

5. The container for fluid material according to claim 1, wherein said at least one inorganic filler is a mineral filler and comprises one or more substances selected from the group consisting of carbonates, kaolins, talc and mixtures thereof.

6. The container for fluid material according to claim 1, wherein a grammage of the paper material is comprised between 50 g/sqm and 900 sqm.

7. The container for fluid material according to claim 1, further including an inner plastic shell for containing the fluid material, wherein the inner plastic shell is coupled to the outer shell, which in turn acts as a substrate for the inner plastic shell.

8. A paper material, including a base substrate having the following formulation: a mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight;at least one polymeric substance, between 1% and 10% by weight;at least one inorganic filler, between 10% and 50% by weight;at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight;aluminum salts, between 1% and 30% by weight;

9. A paper material, including a base substrate having the following formulation: a mixture of cellulose fibres, cotton fibres and synthetic fibres, between 50% and 80% by weight, wherein the synthetic fibres comprise an aliphatic polyolefin and wherein in the mixture of fibres a content of cotton fibres and synthetic fibres is in proportion, varying between 1% and 10% by weight;at least one polymeric substance comprising one or more resins based on colophony, alkyl ketene dimer, acetylsuccinic acid, or epichlorohydrin carboxymethylcellulose, between 1% and 10% by weight;at least one inorganic filler, between 10% and 50% by weight;at least one polyol and/or acrylic polymer and/or starch, between 1% and 10% by weight;aluminum salts, between 1% and 30% by weight;

10. Paper or paperboard comprising the paper material according to claim 8 and any configured as a high rigidity, high fragility substrate and a barrier to water, oils, greases and gas.

11. A method of producing the paper material according to claim 8, the method comprising the steps of: preparing an aqueous mixture of said cellulose fibres, cotton fibres and synthetic fibres, said at least one polymeric substance, and said at least one inorganic filler,removing water from the mixture to form said base substrate of the paper material;carrying out a treatment of said at least one surface of said base substrate with at least one solution based on said aluminum salts and said at least one polyol and/or acylic polymer.

12. The method according to claim 11, wherein said at least one polymeric substance included in said base substrate comprises one or more resins based on colophony and/or alkyl ketene dimer and/or acetylsuccinic acid and/or epichlorohydrin and/or carboxymethylcellulose, and said at least one inorganic filler is a mineral filler and comprises one or more substances selected from in the group consisting of carbonates, kaolins, talc and mixtures thereof.

13. The method according to one claim 11, wherein, after said surface treatment, a step of smoothing said base substrate is carried out, wherein said base substrate is smoothed to ISO 2494 Bendtsen smoothness values of less than about 800 ml/min.

14. The method according to claim 11, further comprising a step of mechanically treating said base substrate to obtain a porosity of 1 sec to 50 sec according to the Gurley method.

15. Paper or paperboard comprising the paper material according to claim 9 and configured as a high rigidity, high fragility substrate and a barrier to water, oils, greases and gas.

16. A method of producing the paper material according to claim 9, the method comprising the steps of: preparing an aqueous mixture of said cellulose fibres, cotton fibres and synthetic fibres, said at least one polymeric substance, and said at least one inorganic filler,removing water from the mixture to form said base substrate of the paper material;carrying out a treatment of said at least one surface of said base substrate with at least one solution based on said aluminum salts and said at least one polyol and/or acylic polymer.

17. The method according to claim 16, wherein said at least one polymeric substance included in said base substrate comprises one or more resins based on colophony and/or alkyl ketene dimer and/or acetylsuccinic acid and/or epichlorohydrin and/or carboxymethylcellulose, and said at least one inorganic filler is a mineral filler and comprises one or more substances selected from the group consisting of carbonates, kaolins, talc and mixtures thereof.

18. The method according to one claim 16, wherein, after said surface treatment, a step of smoothing said base substrate is carried out, wherein said base substrate is smoothed to ISO 2494 Bendtsen smoothness values of less than about 800 ml/min.

19. The method according to claim 16, further comprising a step of mechanically treating said base substrate to obtain a porosity of 1 sec to 50 sec according to the Gurley method.