IT201600073544A1 - METHOD TO MAINTAIN THE CIRCULAR FORM OF THE CENTRAL HOLE OF CORELESS TISSUE PAPER ROLLS AND ITS ROLL - Google Patents

Description

"METHOD TO MAINTAIN THE CIRCULAR SHAPE OF THE CENTRAL HOLE OF CORELESS ROLLS OF TISSUE PAPER AND RELATIVE ROLL"

DESCRIPTION

The present invention refers to a method for maintaining the circular shape of the central hole of "coreless" rolls of "tissue" paper such as toilet paper, kitchen towels or the like, mainly intended for daily mass consumption (the so-called "Consumer "), And the relative roll.

In particular, the present invention refers to such a method which provides for the application of a particular liquid on the first part of the roll of tissue paper, embossed and / or laminated, which is wound on the spindle of the rewinder so as to form a loop of coils. stiffer than the normal turns of a tissue paper roll, said turns stiffer than said ring being able to detach from each other when the roll is in use.

Said stiffer ring of coils has the function of preserving the quality and size of the hole in the roll itself during the cutting, packing, palletizing and transport phases of the rolls, thus making the rolls obtained also suitable for non-centerpull dispensers. ".

It is known in the art to manufacture coreless rolls of "tissue" paper, the so-called "coreless", which can be obtained on central winding rewinders or peripheral winding rewinders, using various technologies.

These "coreless" rolls of "tissue" paper have in common the fact that they do not have a central core in cardboard or other materials, and have a central hole formed by the same "tissue" paper that constitutes the product.

Due to some technological limitations, these rolls are generally dedicated to the so-called institutional or industrial and / or community market and not to the so-called “consumer” market.

Particularly soft "coreless" rolls suitable for the "consumer" market are obtained with the technology described in the patent US 20 14/00841 02A1 in the name of the Applicant: this technology, based on the use of a special elastic mandrel for winding the material in the rewinder, it allows to obtain rolls with a particularly regular and round hole.

However, in the cutting phase of the log in a miter saw to generate rolls, and even more so, in the subsequent phases of packing and palletizing the rolls obtained from the log, the hole obtained using the aforementioned technology may lose part of the desired characteristics, depending on the type. paper, the number of plies and the process used to obtain them: in particular the hole in the roll may lose its roundness or the paper coils that delimit the hole may separate from the other coils, to the detriment of the aesthetic result and / or of the desired functionalities, as illustrated in Figure 1 (a, b, c) attached to the present application which illustrates respectively a coreless roll with an optimal hole, one with a slightly deformed hole and one with a strongly deformed hole.

Methods are known in the art for maintaining the circular shape of the central hole of rolls of various materials including paper, plastic and fabric, which involve the use of various fixing liquids, for example water, adhesives, starch or carboxymethylcellulose solutions up to 2%, on the first meters of product of the roll being wound in order to stiffen the hole itself for the subsequent cutting phases, creating a virtual core formed by the same material being wound which gives stiffness and stability to the shape of the roll and the hole without use traditional cardboard cores.

In the case of "industrial" type rolls, these methods produce an appreciable result, but not ideal for "consumer" products due to some limitations:

• the glues and starches tend to “glue” the plies together, resulting in a roll of product that cannot be used totally with consequent waste of material;

• the geometric characteristics of the hole are of low quality for use in non "centerpull" dispenser systems;

• the aesthetic result is of low quality and in any case not acceptable for so-called “consumer” products.

The purpose of the present invention is to overcome, at least in part, the disadvantages of the known art by providing a method for maintaining the circular shape of the central hole of "coreless" rolls of "tissue" paper intended for daily mass consumption (the so-called products "Consumer"), which allows to preserve the quality and size of the hole in the roll itself during the cutting, packaging, palletizing, and transport phases of the rolls, and which at the same time reduces, or even eliminates, the waste of paper, such to make these rolls also suitable for non-centerpull dispensers.

A further object is to provide such a method which is simple to carry out and also economical and which uses low cost liquids / substances.

These purposes are achieved by the method according to the invention having the characteristics listed in the attached independent claim 1.

Advantageous embodiments of the invention appear from the dependent claims.

An object of the present invention relates to a method which provides for: the application of a particular stiffening liquid, preferably water-based, on the first part being wound of a roll without a tissue paper core, so as to form, after evaporation and winding around a a mandrel, a more rigid coils ring than the normal coils of the tissue paper roll, where said stiffer coils of said ring are able to detach from each other thanks to the nature of the liquid which causes said coils to be more rigid

- do not remain "glued" to each other;

- maintain the appearance of the original product;

- keep the color of the original product;

- keep the softness of the original product to the maximum;

- have no smell;

- are compatible with the tissue paper standard in force.

The aforesaid characteristics mean that the coreless roll obtained with the above method can be destined for the "consumer" market since it can be used advantageously at 100% or at least, with a very low waste of paper.

In this method, the application of the particular stiffening liquid takes place, preferably, through a system of calibrated and PLC-controlled nozzles.

Said system of nozzles is mounted in correspondence with the winding area of a tissue paper rewinder, preferably of a rewinder described in US 2014 / 0084102A1 in the name of the Applicant, incorporated herein by reference, in which a low inertia mandrel and weight, axially elastic, which behaves like a cardboard core during winding.

As already mentioned, the more rigid coils ring has the function of preserving the quality and the dimensions of the hole in the roll itself during the cutting, packaging, palletizing, and transport of the coreless roll of tissue paper, so as to make these rolls also suitable for non-centerpull dispensers, the aforementioned stiffening liquid therefore allows the coils involved in the application to form a core inside the roll that has sufficient compressive strength so as to allow the dimensional characteristics of the hole to be maintained.

The applied quantity of stiffening liquid is limited to prevent the aqueous component of said liquid from being absorbed by the other turns of the roll, given the absorbent nature of the tissue paper, and to reduce drying times, which are calibrated according to the speed of the rewinder. and the type of log accumulator installed in the production line.

However, it should be noted that in the present method, after the phase of applying the liquid, an evaporation phase of the aqueous part can be provided by means of heat-supplying means, known in the art, which are able to cause the loss of the liquid rather quickly. aqueous component, such as, for example, puffs of hot and dry air installed in the log accumulator area which allow to accelerate the drying process of the sprayed liquid; other methods may include infrared systems or radio frequency heating.

It is understood that the above evaporation / drying methods can be used in combination with each other.

In this way, the “coreless” roll of “tissue” paper obtained with this method has the first turns wound on the mandrel already sufficiently stiffened for cutting with a miter saw, even after only 10 minutes from the production of the roll itself.

The water-based stiffening liquid used in the method according to the present invention is an aqueous solution / dispersion selected from

(a) aqueous solutions of (neutral) glues where the glue is chosen from among the glues for gluing the end flap and pick-up glues, more preferably with the end flap;

(b) aqueous solutions of polyanions, preferably selected from the solutions of sodium carboxymethylcellulose;

(c) polycation solutions, such as for example Poly (diallyl dimethyl ammonium chloride);

(d) aqueous solutions of cationic or anionic starches, preferably cationic such as for example the “vector” produced by Roquette Naturai Polymers;

(e) aqueous solutions / dispersions of cationic inorganic fillers, or nanofillers, preferably sodium and calcium bentonite, more preferably calcium bentonite;

(f) combinations of two or more components selected from (a), (b), (c), (d), (e).

With regard to the aqueous solutions (a), the quantity of glue for fine edge glue is preferably such as to obtain water-glue dilutions comprised between 1: 1 and 1: 8, preferably comprised between 1: 1 and 1: 3.

With regard to aqueous solutions (b) of polyanions, if sodium carboxymethylcellulose is used, it is preferable to use a content of the same up to 3% by weight with respect to the weight of the solution.

Furthermore, it is preferable to use a sodium carboxymethylcellulose having a molecular weight from 90 kDa to 300 kDa, preferably 250 kDa.

With regard to the aqueous solutions (c) of polycations, a concentration of up to about 20% by weight of substance is preferable.

With regard to the aqueous solutions (d) of cationic or anionic starches, the amount of starches, preferably cationic, is preferably up to 3% by weight with respect to the weight of the solution, more preferably around <5> 1%.

With regard to the aqueous solutions / dispersions (e) of nanofillers, it is preferable that they contain nanofillers in concentrations up to 20% by weight, more preferably in concentrations ranging from 10% to 20% by weight, even more preferably around 10%.

When used in combination with each other, the aforementioned components (a), (b), (c), (d), (e) can first be mixed together and the resulting mixture sprayed on the roll, or they can be sprayed separately in a way sequential, without departing from the scope of the present invention.

Preferred embodiments of the stiffening liquid are formulations which contain at least one solution / dispersion (e) of nanofillers and at least one other component selected from components (a), (b) and (d).

The Applicant has in fact found that, in many cases, the stiffness of the coil ring of the first winding part is high and the drying time is further reduced if formulations containing component (e) are used, in particular calcium bentonite, in addition to one or more of the components (a), (b), (d).

An example of such a particularly preferred combination formulation is that formulated by

- 2/3 of a solution of glues (a), or polyanions (b) or cationic / anionic starch (d) as defined above, having a product concentration in case (a) equal to about 1 part of glue and 2 parts of water, in case (b) or (d) equal to about 3% by weight; And

- 1/3 of a solution / dispersion (e) containing from 10% to 20% by weight, preferably 10% by weight, of calcium bentonite.

A further particularly preferred embodiment is a formulation comprising

(b) a solution containing from 5% to 3% by weight, preferably 1-1.2%, of sodium carboxymethylcellulose (molecular weight 250 kDA); And

(e) a dispersion of calcium bentonite at 10% by weight,

where solution (b) and dispersion (e) can be mixed together, preferably with 2/3 of (b) and 1/3 of (e), and the resulting mixture sprayed on the roll, or (b) and ( e) can be sprayed separately in a sequential manner, first the solution (b) and then the dispersion (e) or vice versa.

As mentioned above, the overall quantity of stiffening liquid applied to the first portion of the roll being wound is limited, generally 1 ml per 1 m of paper, so as to prevent the aqueous component of said liquid from being absorbed by the other turns of the roll given the nature of the Tissue paper.

The term "first portion of the roll being wound" here is intended to identify, depending on the diameter of the hole chosen for the coreless roll, a portion of paper that is suitable for forming at least two coils wound around the mandrel or even more.

An example of a first section of roll being wound to be treated can be, for example, a section of about 500-1500 mm of tissue paper.

Further features of the invention will become clearer from the detailed description that follows, referring to a purely exemplary, and therefore non-limiting, embodiment illustrated in the attached drawings, in which:

Figure 1 (a, b, c) shows respectively a coreless roll with an optimal hole, a coreless roll with a slightly deformed hole and a coreless roll with a strongly deformed hole.

Figure 2 is a schematic view of a rewinder for rolls of Tissue paper or the like, including a system for applying the stiffening liquid according to the present invention;

Figure 3 is a graph showing the stiffness data (expressed in N / mm) of the loop ring of the first winding section as a function of some stiffening liquids in accordance with the invention.

A rewinder for "tissue" paper rolls or similar, indicated in Figure 1 with the numerical reference 100, has a series of rolls 1, 2, 3, 4, 5 normally provided in any paper rewinder and a mandrel 10 around the first section of paper treated in accordance with the invention will be wound.

Said mandrel 10 is preferably an elastic mandrel with low inertia and weight, axially elastic, as described in US 2014 / 0084102A1 in the name of the Applicant and incorporated herein by reference.

The present rewinder 100 is associated with a liquid application system which provides one or more nozzles 6 arranged so as to cover the entire width of the sheet of paper passing through a first pair of rollers 1 and 2 placed upstream of the mandrel 10.

Said nozzles 6 are fed by the stiffening liquid as defined above, contained in a relative tank 7, generally under pressure.

The stiffening liquid application system also provides a PLC 8 and an operator panel 9 to control and program the application of the liquid based on the transit speed of the paper in the rewinder.

The nozzles 6 are controlled by a series of solenoid valves and proportional valves (not shown in the figure), controlled by the PLC 8, in a manner known per se in the art of nozzles.

In particular, PLC 8 controls the following parameters:

- Liquid pressure in tank 7;

- Spray start position with respect to the roll winding start;

- Fine spray position with respect to the roll winding start;

- Spray pressure nozzles;

- Nozzle system position.

By appropriately setting the above parameters it is possible not only to apply the stiffening liquid in the desired area (generally the first 500-1500 mm of winding) but also to distribute it in the desired quantity based on the speed of the production line.

The aforesaid liquid spray / nebulization system further comprises, as already said, means for supplying heat to the section of paper treated with the stiffening liquid, which are arranged downstream of the spray / nebulization nozzles.

In practice, the present method provides for the application of a certain quantity of a stiffening liquid on the initial section (i.e. first part) of the roll of tissue paper, embossed and / or laminated, before being wound on a mandrel of a rewinder in a way to form, in correspondence with said mandrel, a ring of turns more rigid than the subsequent turns.

Some illustrative but not limitative examples of the present invention follow.

EXAMPLES

Example 1

In the laboratory, foamed specimens of about 500-1000 mm of embossed / laminated tissue paper were made, each of which was intended to be sprayed with a specific test liquid according to the invention, by means of an airbrush, and then said specimens were wound on a spindle of suitable diameter in order to simulate the desired virtual core.

The stiffening fluids tested were the following:

- Water-glue solution at the end of the flap in concentration 1 part of glue, 2 parts of water;

- 20% solution of polycations;

- Sodium water-carboxymethylcellulose solution with molecular weight 250 Kda concentration equal to 1%;

- Water-cationic starch solution in a concentration equal to 1%;

- Pick up glue solution with a concentration equal to 1 part of glue per 8 parts of water.

Each of said liquids was applied as such on the specimens in quantities respectively equal to 1mL, 2mL, 3mL.

In addition, each of said liquids was added with a 10% dispersion of calcium bentonite (CalO) and with a 20% dispersion of calcium bentonite (Ca20), in a quantity such as to have a ratio between liquid and solution equal to 2/3 of liquid and 1/3 of dispersion.

After drying, the specimens obtained were tested with a precision dynamometer to measure the force generated by the vertical compression of the same, to obtain a measurement of the stiffness of the virtual cores.

A graph (Fig. 2) shows the stiffness data (expressed in N / mm) obtained for the specimens treated with the following solutions / dispersions, depending on the quantities sprayed:

- Solution of polycations (PDDA in the graph) at 20%;

- Sodium water-carboxymethylcellulose solution with molecular weight 250 Kda (250CMC in the graph) in a concentration equal to 1%;

- Pick up glue solution (CORE in the graph) with a concentration equal to 1 part for 8 parts of water.

The present invention is not limited to the particular embodiments previously described and illustrated in the annexed drawings, but numerous detailed modifications can be made to it, within the reach of the person skilled in the art, without thereby departing from the scope of the invention itself, such as defined in the appended claims.

Claims (10)

CLAIMS 1. Coreless roll of tissue paper, for example of the hygienic or kitchen towel type, comprising a plurality of paper turns and a virtual core formed by a loop of turns, arranged in correspondence with the central hole, which is rigid with respect to the remaining turns , said ring of stiffer coils being formed by wrapping the initial section of paper pretreated with a stiffening liquid, preferably water-based, said stiffening liquid being selected from (a) aqueous solutions of glues for gluing the end flap and pick-up glues; (b) aqueous solutions of polyanions; (c) solutions of polycations; (d) aqueous solutions of cationic starches or anionic starches; (e) aqueous solutions / dispersions of cationic inorganic fillers or nanofillers; (!) combinations of two or more components selected from (a), (b), (c), (d) and (e), mixed together or applied separately in sequence. Roll according to claim 1, wherein the polyanion solution (b) used is a sodium carboxymethylcellulose solution having a molecular weight between 90 kDa and 250 kDa. Roll according to claim 1 or 2, wherein the inorganic filler used in the solution / dispersion (e) is calcium Bentonite. 4. Roll according to claim 1, wherein the stiffening liquid is a mixture of aqueous solution of glues (a), preferably glues for gluing the end flap, and of an aqueous solution / dispersion of inorganic fillers (e), preferably Bentonite calcium. Roll according to claim 1, wherein the stiffening liquid is a mixture of cationic or anionic starch solution (d), preferably cationic starch, and an aqueous dispersion of inorganic fillers (e), preferably calcium Bentonite. 6. A roll according to claim 1, wherein the stiffening liquid is formed from 2/3 of a solution of glues (a), or polyanions (b) or cationic / anionic starch (d) as defined above, having a product concentration in case (a) equal to about 1 part of glue and 2 parts of water, in case (b) or (c) equal to about 3% by weight; And 1/3 of a solution / dispersion (e) containing from 10% to 20% by weight, preferably 10% by weight, of calcium bentonite. 7. A roll according to claim 1, wherein the stiffening liquid comprises (b) a 1% to 3% by weight solution of sodium carboxymethylcellulose with a molecular weight of about 250 kDA; And (e) a dispersion of calcium bentonite at 10% by weight, where (b) and (e) can be mixed together or applied separately in sequence. 8. Roll according to any one of the preceding claims, in which the initial section of paper pre-treated with a stiffening liquid as defined in any of the preceding claims, is subjected to a flow of heat before winding on the mandrel. 9. A method for obtaining the coreless roll of tissue paper as defined in any one of the preceding claims comprising the steps of applying an aqueous-based stiffening liquid to the first portion of the roll of paper being wound to form, after evaporation and wrapping around to a mandrel, a ring of turns stiffer than the remaining turns of the tissue paper roll. 10. Apparatus for implementing the method according to claim 9 for the production of "coreless" rolls with a central hole of circular shape, comprising - a rewinder (100) for rolls of "tissue" paper or similar, suitable for wrapping said tissue paper around a mandrel (10); - a liquid spray / nebulization system arranged in proximity to said mandrel (10) of said rewinder (100) and optionally means for supplying heat arranged downstream of said spray / nebulization system.