RU2762259C2 - Caseless roll of absorbing sheet and its manufacturing method - Google Patents

Abstract

FIELD: absorbing products.SUBSTANCE: invention can be used for the manufacture of absorbing products, such as sanitary napkins, toilet paper or towels. A caseless roll of an absorbing sheet product formed as a spirally wound continuous web has an axial hollow opening placed in the center of the roll. An absorbing material layer has density from 50 to 140 mg/cm3. At least the last turn of absorbing material spirally wound around the axial hollow opening includes a covering polymer composition. At least 20% of the total length of the continuous web of absorbing material includes the covering composition containing non-ionic polymer in the amount from 0.001 to 40 g/roll. A method for manufacturing a caseless roll of an absorbing sheet product and its use are also proposed.EFFECT: providing the resistance to flattening, as well as flexibility, elasticity and firmness of the caseless roll.26 cl, 9 dwg, 1 tbl

Description

Technology area

The present invention relates to a coreless absorbent sheet roll as an article such as sanitary napkins, toilet paper, towels, etc. In one aspect of the present invention, the coreless roll is formed in a compressed form. The present invention also relates to a method for making a coreless roll.

State of the art

Products made from absorbent sheets in roll form are widely used in modern society. Rolls of toilet paper, towels such as household (kitchen) towels or hand towels, etc. are in constant demand in the trade.

Homemade absorbent sheet rolls (eg, toilet paper) typically consist of a continuous web of absorbent sheet material that is spirally wound around a prefabricated core made of a rigid material such as cardboard or glued paper. The core forms an axial hollow opening that is positioned centrally relative to the roll and extends from one end of the roll to the other. The axial hollow opening allows the user to easily position the roll on the roll holder shaft. However, the liner is expensive, requires storage space and additional manual handling. In addition, the sleeve remains after use of the absorbent sheet product, thereby increasing the risk of clogging the sewer system.

To solve these problems, “tubeless” rolls and rolls with water soluble tubes have been developed. The most important properties of these products are their resistance to flattening and their flexibility / resilience.

"Flattening" as used herein refers to the phenomenon that occurs when the first inner turns of the roll (ie, turns forming an axial hollow opening when winding begins) of the absorbent sheet article cannot be stably held so that the axial hollow opening is well defined. Generally, tubeless rolls are associated with an increased risk of flattening. Flattening usually occurs during the production of coreless rolls, when the temporary core is removed after winding is complete, or during storage and transport of the finished product. Due to the flattening, it becomes difficult to place the roll on the roll holder shaft. Moreover, flattening tends to give consumers a feeling of reduced quality.

The "flexible" roll provides the advantage that it can be formed in a compressed form, which requires less space during storage and transport. As a result, storage and transportation costs can be significantly reduced. The roll can be compressed by applying and maintaining pressure perpendicular to the axial hollow opening to obtain a roll having an oval cross-section. The roll can be held in this compressed form during storage and transportation, for example by being tightly wrapped with packing material around the roll (s).

The roll must also exhibit a certain level of "elasticity" so that it can substantially spontaneously return from a compressed (oval) shape to an uncompressed (cylindrical) shape (for example, when the package is opened) while reopening the axial hollow opening to a well-defined states. That is, the axial hollow opening must open independently and be clearly defined when the roll returns to its cylindrical shape. This requires that the first inner turns again and stably maintain the axial hollow opening. As a result, there should be no significant visible difference in appearance between a roll that has returned from a compressed form to an uncompressed form and a roll that has not been compressed.

In addition, the roll can be subjected to deforming forces during storage and transport, for example, radial forces applied in the unwinding and / or cutting device, axial loads during packaging, and / or when the packaged roll products are stacked on pallets for storage. / shipment, etc. Due to deforming forces, the continuous web of absorbent material may deform irreversibly and the roll may lose its cylindrical shape, thereby giving consumers a perceived degraded quality. Therefore, the roll must combine a certain level of axial and radial stiffness (sometimes also called "rigidity") with superior resilience, which implies that the roll can regain its original size and shape when deforming forces are no longer applied. This requires that the continuous web of absorbent material constituting the roll exhibits adequate internal resistance to deformation. Therefore, the roll must maintain its size and shape regardless of whether it has been subjected to external deforming forces and / or compression.

The prior art describes methods of making roll absorbent sheet products that are indicated as flexible and can be formed in a compressed form.

Patent document WO 2009/027874 A1 discloses a roll comprising a web of nonwoven fabric that is spirally wound around a flexible core. The flexible sleeve includes a resin sheet of synthetic resin that is bonded to the inner layer of the nonwoven web by means of a bonding means such as adhesive, heat bonding, etc. The flexible core has a higher machine direction tensile strength than nonwoven fabric. As a result, the roll is flexible for packaging and storage purposes.

However, synthetic resin resin sheet is pre-fabricated, stored and handled by hand. In addition, in industrial production, a continuous web of absorbent material travels at a speed of about 10 m / s. This makes it technically difficult to insert and attach the resin sheet to the core nonwoven layer at travel speeds required for industrial production.

Moreover, the nonwoven web forming a roll does not exhibit elasticity. As a consequence, when the roll is returned from a compressed form to an uncompressed form, and / or is subjected to external mechanical constraints, the nonwoven web that is spirally wound around the flexible core does not return to its original position and the roll remains in an oval shape, that is, it exhibits low elasticity. This heightens the perception of poor quality among consumers.

Patent document WO 95/13183 A1 discloses a roll of elongated material having a core at the center of the roll. The sleeve essentially includes several turns of elongated material that are held together by a bonding material such as polyvinyl acetate, polyacrylate, latex, starch, polyvinyl alcohol, etc. Patent document WO 95/13183 A1 also discloses a method for producing such a compressed roll. More specifically, patent document WO 95/13183 A1 discloses that a binder solution is sprayed on or coated onto the first turns of a conventional winding. Upon completion of winding and removal from the winding shaft, the roll is immediately compressed to an elliptical or oval cross-section. The document describes that the roll can be released from the compressed form by applying pressure to the "shorter" sides of the ellipse.

However, a binder as described in WO 95/13183 A1 (eg latex, starch, polyvinyl alcohol, etc.) creates a rigid sleeve that includes several turns of glued elongated material. Therefore, the resulting sleeve has no flexibility and exhibits low elasticity. As a result, after the coil has been compressed, it is difficult to reopen its axial hollow opening in a way that results in a well-defined axial hollow opening. In addition, the first inner turns of the elongated material (ie, the turns of the elongated material forming the sleeve) are held adhered to each other by means of a bonding material. The peel force required to separate the first inner wraps is generally higher than the tensile strength of the elongated absorbent material. Therefore, it is difficult to separate the first inner turns without breaking the elongated material on which the bonding material is applied. As a result, it is not possible to use an elongated absorbent material along its entire length, that is, up to the last sheet.

Moreover, the elongated material does not have sufficient elasticity. As a consequence, when the roll returns from a compressed form to an uncompressed form and / or is subjected to external mechanical constraints, the roll-forming elongate material does not substantially return to its original position and the spirally wound elongate material does not substantially return to its original position, and the roll remains in an oval shape, that is, it exhibits low elasticity. This heightens the perception of poor quality among consumers.

Therefore, it is desirable to provide a coreless roll of absorbent sheet product that combines excellent resilience (and thus also proper flexibility and resilience), good stiffness, and good crushing resistance with proper peeling force.

It is also desirable to provide a roll of absorbent sheet product that can be used over substantially its entire length (i.e., substantially up to the last sheet) and prevents clogging of sewer systems (decomposition time).

It is also desirable to provide a coreless roll of absorbent sheet product that can be formed in a compressed form in which, after the roll has been compressed, it can substantially return to its original shape and size, and the axial hollow opening can be substantially reopened by a path leading to a well-defined axial hollow opening.

It is also desirable to provide a method for making such a coreless roll of absorbent sheet product.

The essence of the invention

The present invention relates to (according to "claim 1") a coreless roll of absorbent sheet product, such as sanitary napkins, toilet paper, towels, etc., formed from a continuous web of absorbent material having a first end and a second end, the continuous web of the absorbent material is spirally wound so as to create an axial hollow opening located in the center of the relatively coreless roll and extending from one end to the other end of the coreless roll, and such that the first end is located on the outside of the roll and the second end is located at the axial hollow opening:

moreover, the spirally wound continuous web of absorbent material has a density of from 50 to 140 mg / cm ³ , preferably from 60 to 130 mg / cm ³ , more preferably from 70 to 120 mg / cm ³ ;

wherein at least the last turn located at the second end of the continuous web of absorbent material comprises a cover composition comprising a (preferably non-ionic) polymer comprising oxygen and / or nitrogen atoms, the turn being one turn of the continuous web spirally wound around an axial hollow opening; and

wherein at least 20%, preferably at least 25%, more preferably at least 30%, more preferably at least 35%, more preferably at least 40%, more preferably at least 50% more preferably at least 70% of the total length of the continuous web of absorbent material in the machine direction includes a cover composition containing a non-ionic polymer comprising oxygen and / or nitrogen atoms.

The present invention also relates to such a coreless roll that is formed in a compressed form.

In one aspect of the present invention, the coating composition applied to the second end is the same as applied along the entire length of the continuous web of absorbent material.

In one further aspect of the present invention, the coating composition is applied to a continuous web of absorbent material such that the maximum inter-sheet adhesion between the coated portions of the continuous web and the portions of the continuous web in contact therewith is 0.3 to 1.7 N.

In one additional aspect of the present invention, the nonionic polymer is a nonionic cellulose ether such as an alkyl cellulose ether, a hydroxyalkyl cellulose ether, or combinations thereof, or a hydroxyl-terminated polyether such as polyethylene glycol, polypropylene glycol, or combinations thereof.

The present invention includes the following embodiments (“clauses”):

2. The linerless roll according to claim 1, wherein the coating composition is applied to only one side of the continuous web of absorbent material, preferably the side facing the axial hollow opening.

3. The sleeveless roll according to paragraph 1 or 2, wherein the polymer comprising oxygen and / or nitrogen atoms contained in the coating composition, which is applied to the last coil (s) located at the second end, is a non-ionic polymer, and preferably said coating composition is the same as a composition applied over at least 20% of the entire length of a continuous web of absorbent material.

4. A coreless roll according to any one of claims 1 to 3, wherein the maximum inter-sheet adhesion between the coated portions of the continuous web of absorbent material and the portions of the continuous web in contact therewith is 0.3 to 1.7 N.

5. The linerless roll according to any one of claims 1 to 4, wherein the coating composition that is applied to the continuous web of absorbent material has an ionic requirement of -1000 to +100 μeq / g, preferably from -500 to +50 μeq / g, more preferably -50 to 0 μeq / g.

6. The linerless roll according to any one of claims 1-5, wherein the non-ionic polymer comprises at least one repeating structural unit containing one or many oxygen atoms and / or one or many nitrogen atoms.

7. The linerless roll according to claim 6, wherein the non-ionic polymer comprises at least one repeating structural unit containing one or many oxygen atoms of an ether group and / or one or many hydroxyl groups.

8. A linerless roll according to claim 6 or 7, wherein on average at least 50%, preferably at least 80%, of all repeating units making up the nonionic polymer include one or many oxygen atoms and / or one or many nitrogen atoms preferably ether oxygen atoms and / or one or more hydroxyl groups.

9. The linerless roll according to any one of claims 1 to 8, wherein the non-ionic polymer is a non-ionic cellulose ether.

10. The coreless roll according to claim 9, wherein the nonionic cellulose ether has a number average molecular weight of 1,000 to 1,000,000, preferably 2,000 to 500,000, more preferably 3,000 to 200,000, more preferably 5,000 to 100,000.

11. The linerless roll according to claim 9 or 10, wherein the nonionic cellulose ether is an alkyl cellulose ether such as methyl cellulose or ethyl cellulose, a hydroxyalkyl cellulose ether such as hydroxyethyl cellulose or hydroxypropyl cellulose, or a combination thereof.

12. The linerless roll according to any one of claims 1 to 8, wherein the non-ionic polymer is a hydroxyl-terminated polyether, preferably a hydroxyl-terminated polyether selected from polyethylene glycol, polypropylene glycol and mixtures thereof, more preferably polyethylene glycol, and in which preferably at least 40%, more preferably at least 50%, more preferably at least 70%, of the total length of the continuous web of absorbent material in the machine direction includes a cover composition containing a hydroxyl-terminated polyether.

13. The coreless roll according to claim 12, wherein the nonionic polymer has a number average molecular weight of 800 to 250,000, preferably 1,000 to 50,000, more preferably 1,500 to 15,000, more preferably 1,500 to 10,000, more preferably 2,000 to 7,500, for example from 2500 to 4000.

14. A linerless roll according to any one of claims 1-13, wherein the coating composition comprises:

(a) at least 50 wt.%, preferably at least 65 wt.%, more preferably at least 80 wt.% non-ionic polymer;

(b) not more than 50 wt.%, preferably not more than 35 wt.%, more preferably not more than 20 wt.% additional additives such as plasticizers, hardening agents, fragrances and colorants;

in each case based on the total solids content of the coating composition.

15. The linerless roll according to any one of claims 1 to 14, wherein the coating composition is applied in molten form, or, after addition of water, in the form of an aqueous solution, the aqueous solution preferably containing a non-ionic polymer in an amount of at least 0.1 wt.% more preferably at least 0.5% by weight, based on the total weight of the coating composition.

16. The tubeless roll according to any one of claims 1-15, in which at least the last two, preferably at least the last three turns, preferably at least the last five turns, more preferably at least the last ten turns located at the second end of the continuous webs of absorbent material include a cover composition.

17. The linerless roll according to any one of claims 1-16, wherein the coating composition is applied such that, with respect to the length or lengths of the continuous web that includes the coating composition, the coating composition covers an area of at least at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90% of the total area of said length (s) of portion (s) ).

18. The linerless roll according to any one of claims 1-17, wherein, if the coating composition has been applied continuously in the machine direction, the formed coated portion begins at the second end and includes at least the last turn of the second end.

19. The linerless roll according to any one of claims 1-17, wherein if the coating composition has been applied intermittently in the machine direction, thereby creating two or more coated areas, (i) one coated area includes at least the last turn of the second end, and (ii) the amount of nonionic polymer applied to the continuous web half including the second end is preferably equal to or greater than the amount of nonionic polymer applied to the continuous web half including the first end.

20. A coreless roll according to any one of claims 1 to 16, wherein the total amount of nonionic polymer is 0.001 to 40 g / roll, preferably 0.005 to 10 g / roll, more preferably 0.005 to 5 g / roll, in particular from 0.01 to 2g / roll.

21. A coreless reel according to any one of claims 1 to 20, wherein the absorbent material web is constituted by 1 tissue paper layer, or 2 to 6, in particular 2 to 5 superimposed tissue layers.

22. A coreless roll of absorbent sheet product formed by a spirally wound continuous web of absorbent material having a first end and a second end, the web of absorbent material being wound to define an axial hollow opening centered on the coreless roll and extending from one edge to the other edge a sleeveless roll, and so that the first end is on the outside of the roll, and the second end is at the axial hollow opening;

moreover, the linerless roll has an elasticity in 30 seconds of at least 75%, preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, and the elasticity in 30 seconds is determined as described in the description ...

23. The coreless roll according to claim 22, wherein the roll has a diameter of 50 to 500 mm, preferably 80 to 200 mm, more preferably 100 to 155 mm.

24. A coreless roll according to clause 22 or 23, which is defined as in one or more of clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 , 17, 18, 19, 20 or 21.

25. A linerless roll according to any one of claims 1-24, in a compressed form.

26. A linerless roll according to any one of claims 1-25, which is an absorbent article selected from the group consisting of sanitary napkins, towels such as household towels, kitchen or hand towels, toilet papers, wiping papers, handkerchiefs , and facial tissues, the absorbent article preferably being toilet paper.

27. A manufacturing method for obtaining a coreless roll of an absorbent sheet product, comprising:

- moving a continuous web of absorbent material having a first end and a second end, which is preferably composed of 1 tissue paper layer, or 2 to 6, in particular 2 to 5, superposed tissue layers;

optionally cutting the continuous web of absorbent material substantially cross-machine direction to produce single but interlocked sheets;

- applying a coating composition, as defined in any one of items 1-20, onto a continuous web;

spiraling a continuous web of absorbent material so as to form a long roll (log) of a web of absorbent material, the web of absorbent material being wound so as to define an axial hollow opening positioned in the center of the log and extending from one edge of the log to the other edge of the log, and so that the first end is on the outside of the log, and the second end is at the axial hollow opening; and

- cutting the log into numerous caseless rolls.

28. The manufacturing method according to paragraph 27, further comprising

- subjecting a tubeless roll to compression in the direction perpendicular to the axial hollow opening to obtain a tubeless roll in a compressed form.

29. The manufacturing method according to claim 27 or 28, wherein the linerless roll obtained by this method is as defined in one or more of items 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24.

30. The use of the coreless roll according to any one of claims 1-26 as toilet paper, household towel, hand towel, kitchen towel, wiping paper, facial tissue, handkerchief, or sanitary napkin.

Where the present description refers to “preferred” embodiments / features, combinations of these “preferred” embodiments / features should also be considered disclosed insofar as this combination of “preferred” embodiments / features is technically significant.

Above and below, in the present description and in the claims, the use of the term “including” is to be understood as a disclosure, as a more limited embodiment, and also as the term “consisting of” insofar as it is technically significant.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing a perspective view of a coreless roll according to one embodiment of the present invention.

FIG. 2 is a schematic diagram showing a side view of a coreless roll according to one embodiment of the present invention. The second end, as shown in FIG. 2 has three turns.

FIG. 3 is a schematic diagram showing an unwound continuous web of absorbent material according to one embodiment of the present invention. The gray shading in FIG. 3 shows a cover composition that is applied to the last turn (s) located at the second end and which is continuously applied to a continuous web of absorbent material. The combined coated portions of the continuous web of absorbent material (i.e., the coated last turn (s) located at the second end and the continuously coated web) constitute about 50% of the total length of the web in the machine direction (MD).

FIG. 4 is a schematic diagram showing an unwound continuous web of absorbent material according to one embodiment of the present invention. The gray shading in FIG. 4 depicts a cover composition that is applied over about 3 turns at the second end and which is periodically applied to a continuous web of absorbent material. The combined coated portions of the continuous web of absorbent material (ie, the coated last turns at the second end and the intermittently coated web) constitute about 50% of the entire length of the web in MD.

FIG. 5 is a schematic diagram of the last turns at the second end of an unwound continuous web of absorbent material in accordance with one embodiment of the present invention. The gray shading in FIG. 5 shows a coating composition that has been applied continuously to the last turns.

FIG. 6 is a schematic diagram of a covered area (a length of an uncoiled continuous web of absorbent material according to one embodiment of the present invention). The gray shading in FIG. 6 shows a coating composition that is applied intermittently as dots.

FIG. 1-6 provide an overview of the terminology used in relation to the coreless roll of the present invention. In FIG. 1-6, the following reference numbers are shown:

(1) coreless roll

(2) spiral wound continuous web of absorbent material

(3) axial hollow opening

(4) edge

(5) first end

(6) second end

(7) coating composition

(8) perforation line.

FIG. 7 is a schematic view showing a sectional view of a paper machine (9) illustrating the manufacture of coreless rolls according to one embodiment of the invention. FIG. 7 shows the spray application of a coating composition to a continuous web of absorbent material.

FIG. 8 is a schematic view showing a sectional view of a paper machine (9) illustrating the manufacture of coreless rolls according to one embodiment of the invention. FIG. 8 shows the application of a coating composition to a continuous web of absorbent material using a coating roller.

FIG. 9a, 9b and 9c are schematic diagrams of an apparatus (dynamometer) (39) and a set of rollers (40) - (43) suitable for measuring inter-sheet adhesion (peel force) in a tissue roll (44) according to the present invention. The dimensions in FIG. 9a-9c are given in mm.

Detailed description of the present invention

1. Sleeveless roll

The coreless roll of absorbent sheet product according to the present invention is formed from a spirally wound continuous web of absorbent material having a first end and a second end.

The continuous web of absorbent material is preferably made from base tissue paper, which can be obtained by Conventional Wet Press or Through Air Drying (TAD) manufacturing processes, or other manufacturing processes. As used herein, "base (raw) tissue paper"("tissuepaper") means a single ply tissue base paper as obtained from a tissue machine. The base tissue paper has a low basis weight in the range of 8 to 60 g / m ² , preferably 10 to 30 g / m ² .

The term "layer" as used herein means one or more plies of tissue paper in the final tissue article (e.g. toilet paper) when it is / are obtained after processing ("processing") one or more webs of the base sanitary paper.

Given the fundamental compatibility of the production methods (wet forming), the production of "tissue paper" is considered to be papermaking technology. The manufacture of tissue paper differs from papermaking in its exceptionally low basis weight and much higher tensile energy absorption.

Tensile energy absorption is derived from tensile energy absorption, in which the tensile energy absorption is related to the volume of the test specimen before examination (length, width, thickness of the specimen between the clamps before applying the tensile load). Paper and tissue paper also differ, as a rule, with respect to the modulus of elasticity, which characterizes the deformation and strength properties of these planar products as parameters of the material.

The high tensile energy absorption of tissue paper is due to external or internal creping. The former is obtained by compressing a paper web adhered to a dry cylinder by a creping doctor or, in the latter example, by a difference in speed between two meshes ("fabrics"). This causes internal fracture of the plastically deformable, still wet paper web due to compressive and shear forces, thereby making it more tensile under load than uncreped paper. High tensile energy absorption can also be achieved by imparting a three-dimensional (3D) structure to tissue paper using the wire meshes themselves. Most of the functional properties typical of tissue paper and tissue products are due to their high tensile energy absorption (see DIN EN 12625-4 and DIN EN 12625-5).

Typical properties of tissue paper include the ability to easily absorb tensile energy, its drape, good textile-like flexibility, properties often referred to as bulk softness, high surface softness, high specific volume with sensible thickness, and high liquid absorption capacity. and, depending on the application, adequate wet and dry strength as well as an interesting visual appearance on the outer surface of the product. These properties allow the use of tissue paper such as wiping rags (such as household towels), tissue products (such as toilet paper, hand towels) and napkins (such as cosmetic wipes, handkerchiefs) ...

According to one embodiment of the present invention, the continuous web of absorbent material preferably consists of 1 tissue paper layer, or 2 to 5 superimposed tissue paper layers.

Sanitary paper can be made from fibers for papermaking according to "Standard Methods" such as for making "Dry Crepe Tissue" or "Wet Crepe Tissue" creping "), or" Processes for Structured Tissue ", such as the Through Air Drying (TAD) method, the production of non-creped tissue paper, through hot drying air (UCTAD), or alternative manufacturing methods such as Voith's Advanced Tissue Molding System (ATMOS), or Energy Efficient Technologically Advanced Drying eTAD (eTAD) Georgia Pacific, or Structured Tissue Technology SST hygienic paper ") by Metso Paper. Hybrid methods such as NTT (New textured Tissue), which are modifications of traditional methods, can also be used.

The traditional dry creping method includes:

- pressing and drying the wet paper fibers to form a sheet on a heated large diameter cylinder (also called Yankee cylinder); and

- then separating and creping the sheet of dried paper fibers using a metal scraper coupled to the specified cylinder across the direction of its rotation.

The creping operation creates undulating irregularities in the sheet across the direction of its movement. The creping operation increases the thickness of the sheet and gives elasticity and gives the sheet tactile properties (soft to the touch).

The TAD manufacturing method includes:

- forming a sheet of wet paper fibers on a cloth tape; and

- then drying the sheet, at least in part, by means of a stream of hot air passed through it.

The dried sheet can then be creped.

In addition, a method as described in patent document PCT / EP2015 / 059326 (filing date: 04/29/2015; title: Sanitary - sanitary paper, including cellulose fibers derived from miscanthus, and a method of making it ", incorporated by reference). More specifically, reference is made to the description according to paragraph 3 on pages 22-27 of this application, and the details of the TAD method disclosed therein (eg, three-dimensional (3D) web shape, permeable drying cylinder, etc.). The parameters described in this text passage are also suitable for use in ATMOS technology.

Once the tissue paper has been made, a separate process step called a recycling step is usually used to form the tissue paper product (i.e., paper towels, toilet paper rolls, bathroom tissue paper, tissue paper for wipes, kitchen tissue rolls, handkerchiefs, etc.).

In one further embodiment of the continuous web of absorbent material, the absorbent material is a "nonwoven material". The term "nonwoven fabric" is widespread in technology, and can be further defined as described in ISO 9092: 2011, also for the purpose of the present invention. Typical methods of making nonwovens include airlaid technology, spunbond technology, dry lay technology, and long fiber wet lay technology. The web of nonwoven fabric used in this embodiment can be a single layer or a multi-layer web.

According to one preferred aspect of this embodiment, the absorbent nonwoven web used in the coreless roll of the invention comprises cellulosic fibers. In this case, the content of cellulosic fibers, based on the total weight of all fibers present in the nonwoven web, is at least 20 wt%, more preferably at least 50 wt%, for example at least 80 wt%. The rest of the fibers in these cases are non-cellulosic fibers such as synthetic fibers.

The above paper pulp fibers (which may also be referred to as "cellulosic fibers") can be obtained from virgin and / or recycled pulp and paper raw materials. Cellulosic fibers that can be used in the invention usually contain, as the main structure-forming component, the proportion of long-chain fibrous cellulose that is present in natural cellulose-containing cells, in particular in tree cells. The fibers are preferably recovered from tree plants by treatment in cooking steps to remove or reduce lignin and other extractable components, and optionally in bleaching steps. Cellulosic fibers can also come from non-woody sources such as annuals.

Suitable cellulose fibers that can be used can be of the regenerated type (eg Lyocell), although other types of cellulose are preferred. The celluloses used can be primary fibrous material ("primary fibers") or recycled fibrous material (recycled celluloses). The cellulose may come from non-lignin or low lignin sources such as cotton wool, esparto (alpha) grass, pomace (such as cereal straw, rice straw, bamboo or hemp), hemp fibers, miscanthus grass fibers, or flax (also called "non-wood fibers" in the description and in the claims). Preferably, the cellulose is obtained from a lignocellulosic material such as softwood (which usually comes from softwood) or hardwood (usually from deciduous trees).

It is possible to use "chemically treated cellulose" or "mechanically processed cellulose", and therefore it is preferable to use chemically treated celluloses.

"Chemical processed celluloses" as used herein, according to DIN 6730, are fibrous materials obtained from vegetable raw materials, from which most of the non-cellulosic components have been removed by chemical cooking without significant mechanical additional processing. "Mechanically processed cellulose", as used herein, is a general term for a fibrous material made entirely or almost entirely from wood by mechanical means, optionally at elevated temperatures. Mechanically processed pulps can be categorized into purely mechanical pulps (wood pulp and refined mechanical pulps) as well as chemically pretreated mechanical pulps such as chemo-mechanical pulps (CMP) or chemo-thermomechanical pulps (CTMP).

In the present invention, with reference to FIG. 1 and 2, a continuous web (2) of absorbent material is spirally wound so as to form an axial hollow opening (3) centered on the roll (1) and which extends from one end (4) to the other end (4) of the roll ... As used herein, "axial hollow opening" means a tubular opening that extends through the roll along its central axis. The axial hollow opening allows the end user to mount the roll onto the roll holder shaft. When the roll is placed on the roll holder shaft, the absorbent material is dispensed from the first end (outside the roll) while the roll is free to rotate about its central axis. The axial hollow opening has a diameter of 10 mm to 70 mm, preferably 20 mm to 50 mm.

In the present invention, the axial hollow opening (3) is extended from one end (4) to the other end (4) of the linerless roll. The coreless roll of the present invention has a cylindrical circumferential surface and opposing flat ends (ie, edges) that are formed when the roll log is cut into multiple rolls at the end of the winding process. As used here, "edge" means a flat area that is on one side of the roll perpendicular to its central axis.

In the present invention, the continuous web (2) of absorbent material has a first end (5) and a second end (6). The first end (5) is on the outside of the roll and the second end (6) is at the axial hollow opening. Therefore, the continuous web of absorbent material consists, in the machine direction, of a first end and a second end, and a middle portion located between these ends. The combined lengths of the first end, second end, and midsection define the entire length of the continuous web of absorbent material that forms one roll. In the coreless roll of the present invention, the continuous web of absorbent material includes the cover composition provided herein.

The spirally wound continuous web of absorbent material has a (bulk density) density of 50 to 140 mg / cm ³ , preferably 55 to 135 mg / cm ³ , more preferably 60 to 130 mg / cm ³ , more preferably 65 to 125 mg / cm ³ , more preferably 70 to 120 mg / cm ³ , more preferably 80 to 110 mg / cm ³ , for example 80 to 100 mg / cm ³ . The desired density can be achieved, for example, by adjusting the volume (cm ³ / g) of the continuous web of absorbent material and / or the winding force (tension) of the continuous web during the winding process. The result of the increased winding force is that more sheets can be accommodated in a roll of the same diameter, which is also illustrated in the examples given. When the continuous web of absorbent material constituting the roll is wound tightly (for example, due to the higher tension applied during the winding process) and / or exhibits fairly low volume values, the resulting roll exhibits a high density, i.e., a high mass of absorbent material per unit volume. If the density of the resulting roll exceeds 140 mg / cm ³ , the elastic characteristics may not fully develop. In addition, at higher densities, the coreless roll can become relatively stiff and can no longer be compressed to the desired degree, for example, for storage purposes.

In contrast, when a continuous web of absorbent material constituting a roll is wound relatively loosely (for example, due to weaker tension created during the winding process) and / or exhibits fairly high volume values, the resulting roll exhibits a low density, i.e., a low mass of absorbent material per unit. volume. However, a density of less than 50 mg / cm ^{3 is} undesirable due to the increased risk of blocking the unwinder when the continuous web is moving at a speed appropriate for industrial production, for example 10 m / s.

According to the present invention, the coating composition is applied to a continuous web such that it contains at least the last turn located at the second end (6) of the web. By "turn" the authors of the present invention mean one revolution of the spirally wound web around the axial hollow opening (3). For example, FIG. 2 shows the last three turns at the second end (6) of the web. The coating composition is preferably applied to the web such that at least two last turns, more preferably at least three last turns, more preferably at least four last turns, at least five last turns, more preferably at least ten last turns, located at the second end include the coating composition.

According to the present invention, the coating composition is applied to a continuous web of absorbent material continuously or intermittently. In addition, the continuous web of absorbent material is coated such that at least 20% of the total MD length of the continuous web includes the cover composition.

The fraction of the length of the web in the machine direction ("at least 20% of the total length of the web"), as used herein, refers to the total length of the portions of the continuous web in the machine direction, coated with a non-ionic polymer, including atoms of oxygen and / or nitrogen ("first polymer") , relative to the entire (cumulative) length of the continuous web in the machine direction. It may include the last turn (s) located at the second end. With regard to the distribution of the coating composition comprising the first polymer, there is no particular limitation on the entire length of the continuous web, provided that at least 20% of the total length of the continuous web in the machine direction includes this coating composition. Optionally, the same coating composition is applied to the last turn (s) located at the second end of the continuous web.

In one embodiment, the coating composition (s) are applied to the continuous web so that preferably at least 25%, at least 30%, at least 35%, at least 40%, at least 50 %, more preferably at least 70%, more preferably at least 80%, for example at least 90% of the total machine direction length of the web includes the coating composition containing the first polymer. In one preferred embodiment of the present invention, the coating composition is applied along the entire length of the continuous web in the machine direction, that is, the coating composition is applied continuously in the machine direction from the first end (5), located on the outside of the roll, to the second end (6), located at the axial hollow opening (3).

For the avoidance of doubt, the inventors of the present invention would like to point out that these percentages apply to a coating composition comprising only a non-ionic polymer containing oxygen and / or nitrogen atoms (also called "first polymer"). In the case that at the second end of the continuous web at least the last turn comprises a different coating with an ionic polymer containing oxygen and / or nitrogen atoms (also called a "second polymer"), portions of the continuous web containing a coating with a second polymer are not considered for determination of the above values of the percentage.

With reference to the embodiment of FIG. 3, the continuous web of absorbent material has a first end (5) and a second end (6), the last turns at the second end (i.e., the end of the web positioned at the axial hollow opening) include a cover composition, and the continuous web includes a cover composition that is continuously applied in the machine direction. If the same coating composition comprising the “first polymer” is used, the continuously coated area that includes the last coil (s) located at the second end defines the area of coated length (in%), based on the entire length of the continuous web (that is, the combined lengths of the first end, second end, and middle portion that define the entire length of the continuous web of absorbent material forming one individual roll).

With reference to the embodiment of FIG. 4, the continuous web of absorbent material has a first end (5) and a second end (6), the last turns at the second end (i.e., the end of the web positioned at the axial hollow opening) include the cover composition, and the continuous web includes the cover composition that is periodically applied in the machine direction. If the same coating composition is used, including the "first polymer", the continuously coated portion, the combined lengths of the coated last turn (s) located at the second end, and the intermittently coated portions determine the length of the covered area (in%), based on the entire length of the continuous web.

In one preferred embodiment, a polymer comprising oxygen and / or nitrogen atoms ("second polymer") contained in a coating composition that is applied to said last turn (s) located ) at the second end is a non-ionic polymer, and preferably said coating composition is the same as applied to at least 20% of the entire length of the continuous web of absorbent material.

In one further embodiment of the present invention, the coating composition is applied to a continuous web of absorbent material such that the maximum inter-sheet adhesion (peel force) between the coated portions of the continuous web and the portions of the continuous web in contact therewith is 0.3 to 1. 7 N, preferably 0.4 to 1.5 N, for example 0.5 to 1.2 N. The inter-sheet adhesion can be determined as indicated in the experimental section.

In one embodiment, the present invention relates to a coreless roll of absorbent sheet product formed by spirally winding a continuous MD web having a first end and a second end, the absorbent web having a first end and a second end, the absorbent material web being wound to create an axial hollow opening located in the center of the coreless roll and extending from one end to the other end of the sleeveless roll, and so that the first end is on the outside of the roll, and the second end is at the axial hollow opening;

moreover, the linerless roll has an elasticity in 30 seconds of at least 75%, preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, and the elasticity in 30 seconds is determined as indicated in the experimental section.

As is well known to the present inventors, coreless rolls with such excellent resilience characteristics have not been obtained or previously described. The inventors have surprisingly found that such articles can be obtained by applying appropriately selected coating compositions / polymers to a certain percentage over the entire length of a web of absorbent material, and using the coated web to obtain rolls having an appropriately selected density, as described in further details. in the description and in the paragraphs of the appended claims. One advantage of such coreless rolls is the improved visual appearance of the roll after it has been compressed and / or subjected to deforming forces. The higher the elasticity value, the more the axial hollow opening will be additionally reopened after elimination of the deforming / compressive force. The linerless rolls with the stated resilience values will have substantially the same appearance to the consumer before and after compression, and will not give the impression of a low quality product.

In one embodiment, the coreless roll of the present invention is formed in a compressed form. As used herein, "compressed shape" means a shape in which the cross-section of the roll is oval. When the roll is compressed, the axial hollow opening takes on a narrow oval shape (when fully compressed, it forms a narrow oval slot) and the roll holder shaft can no longer be inserted. As a result, less space is required for the roll and storage and shipping costs can be reduced. Due to its excellent resilience values, the coreless roll of the present invention is capable of spontaneously returning from a compressed (oval) shape to a substantially uncompressed (cylindrical or only slightly oval) shape, even if no pressure is applied along the long side (diameter) of the oval shaped roll, i.e. perpendicular to the roll axis.

2. Covering composition (s) used for sleeveless roll

In the present invention, a coating composition comprising a (preferably non-ionic) polymer comprising oxygen and / or nitrogen atoms is applied to at least the last turn located at the second end of the continuous web, and a coating composition comprising a non-ionic polymer comprising oxygen and / or nitrogen is applied to at least 20% of the entire length of the continuous web in the machine direction.

Accordingly, the invention distinguishes between a non-ionic polymer comprising oxygen and / or nitrogen atoms deposited over at least 20% of the entire length of a continuous web (also called a "first polymer"), and a polymer comprising oxygen and / or nitrogen atoms, applied to at least the last turn located at the second end (also called "second polymer"), which can be ionic, but preferably non-ionic, and more preferably the same polymer as used as the first polymer.

The polymers useful in the present invention are described in more detail below in sections 2.1 and 2.2.

If the first and second polymers are identical, it is also preferred that at least the last turn at the second end includes the same coating composition as applied over at least 20% of the entire length of the continuous web. For this preferred embodiment of the invention, the following applies.

The coating composition useful in the present invention preferably comprises:

(a) at least 50 wt% of said nonionic polymer, preferably at least 65 wt%, more preferably at least 80 wt%, more preferably at least 85 wt%, more preferably at least 90 wt% .%, more preferably at least 95 wt.%;

(b) no more than 50 wt%, preferably no more than 35 wt%, preferably no more than 20 wt%, more preferably no more than 15 wt%, more preferably no more than 10 wt%, more preferably no more than 5 wt% .%, additional additives such as plasticizers, hardening agents, fragrances, dyes, etc .;

in each case based on the total solids content of the coating composition.

In one additional embodiment, the coating composition consists of these ingredients in the indicated amounts.

In one embodiment, the coating composition is composed of a non-ionic polymer that preferably has a melting point above 20 ° C, more preferably above 30 ° C, more preferably above 40 ° C, as determined by a dynamic mechanical analyzer (DMA, single-arm bending geometry material pocket ) based on the tan δ characteristic, the measurement being performed from -120 ° C to 75 ° C, with a gradient of 3 ° C per minute and a frequency of 1.0 Hz. One example of such a nonionic polymer is hydroxyl terminated polyethers, described in more detail below.

The coating composition can be applied to a continuous web of absorbent material (in particular its "second end") in a molten state after heating to or above a specified melting point, for example by spraying, controlled fiberization, roll-coating, slot-die application , or any other suitable method of application known in the art.

In one embodiment, the coating composition can be applied as an aqueous solution. This means that water is added to the coating composition and used as a solvent for the nonionic polymer and additional additives, if present. The aqueous solution of the coating composition preferably contains the non-ionic polymer in a total amount of at least 0.1 wt%, preferably at least 0.5 wt%, more preferably at least 1 wt%, based on the total weight of the aqueous solution. Additional additives such as plasticizers, hardening agents, flavors, colorants, etc. may also be present. In this case, too, the preferred levels can be used, explained above in connection with component (b), (but with reference to the total dry matter in aqueous solution).

Water is preferably present in an amount that is more than 50 wt%, and more preferably in an amount of more than 65 wt%, more preferably more than 80 wt%, based on the total weight of the aqueous solution.

This aqueous coating composition solution can be applied as it is, preferably at room temperature, onto a continuous web of absorbent material, for example by spraying, controlled fiberization, roll-coating, or any other suitable application method known in the art. After application of the aqueous solution, the continuous web of absorbent material can be dried, for example, by prolonged storage at ambient conditions, or by other methods known in the art. Depending on the water content, such a drying step may also be unnecessary since the web of absorbent material itself will remove water from the aqueous solution, thereby expelling it outside the coating composition on the web.

In one embodiment, the coating composition is applied to the last turn (s) located at the second end and / or to a continuous web, in the form of an aqueous solution, and has an ionic requirement of -1000 to +100 μeq / g, preferably -500 to +50 μeq / g, more preferably -50 to 0 μeq / g. The expression "ionic demand", as used here, means the total surface charges of all dissolved and undissolved substances present in an aqueous solution. Ionic demand can be measured by methods known in the art such as polyelectrolytic titration. A suitable device for measuring ionic demand is the PCD 03 particle charge detector manufactured by BTG Mütek GmbH, Germany.

In the present invention, the coating composition is applied to at least one of two sides of the continuous web, that is, the top and / or bottom side of the longitudinally continuous web. "Top" side as used herein means the side of the continuous web that faces outwardly relative to the roll when the web is spirally wound. In one preferred embodiment, the coating composition is applied to the "underside", that is, the side facing the axial hollow opening. However, if only a fairly small number of turns, for example, one or two (for example, up to three turns) located at the second end, include a (preferably non-ionic) polymer containing oxygen and / or nitrogen atoms, it may be beneficial to apply the coating composition to " top side ”to ensure that the top side of the individual turns sufficiently adheres to the bottom side of the next turn.

The coating composition is preferably applied to the continuous web before it is spirally wound to form a roll. As a result of winding, the coating composition is applied circumferentially relative to the axial hollow opening. In the present invention, the coating composition is preferably applied to the web such that at least 20%, preferably at least 25%, preferably at least 30%, is covered with respect to the total length of the web (i.e., the portion or portions of length containing the resulting coating) preferably at least 35%, preferably at least 40%, preferably at least 50%, more preferably at least 70%, and in particular at least 80%.

In the present invention, the coating composition is preferably applied such that, with respect to the portion (s) of the length of the continuous web that includes the coating composition, the area covered by the coating composition (whether continuous coating or partial coating) occupies at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90% of the total area of said length portion (s).

The coating composition can be applied to a continuous web to create a solid or partial coating.

"Continuous coating" as used herein means a coating that is applied continuously in the machine direction and axial (transverse) direction. This continuous coating may include the second end of the web (see, for example, Fig. 5).

In accordance with one embodiment of the present invention, it is preferred to apply the coating composition so as to create a continuous coating over the coated portion of the length of the web. This means that with respect to the length of the continuous web that includes the coating composition, the area covered by the coating composition is 100%.

Moreover, it is preferred that such a continuous coating includes the last turn (s) of the second end of the continuous web. In other words, if the same coating composition is used to coat the last turn (s) at the second end as well as the desired length (e.g. 20% or 40%) of the continuous web, the remainder ( 80% or 60%) remains uncovered. In addition, if the coating composition is applied continuously in the machine direction, it is preferred that the resulting coated length begins at the second end and includes at least the last turn of the second end.

Partial coverage is created, for example, if the coating is applied to the web intermittently in the machine and / or axial direction. The coating composition can be applied to the web to form predetermined coating patterns. The applied pattern of the cover composition is preferably symmetrical and centered about an axis of symmetry extending parallel to the machine direction (which divides the absorbent material web into two equal hypothetical halves). There is no particular limitation with respect to the predefined coating pattern. Partial coverage can form cohesive (such as stripes, lines, or waves) or discrete deposits (such as points, squares, circles, or any other geometric shape).

In one embodiment, the coating composition is applied continuously in the machine direction, but intermittently in the axial direction, that is, it does not completely cover the (axial) cross-section. For example, this can be achieved by applying a wide strip ("tape") of the coating composition over the desired length of the entire continuous web. This wide strip of the coating composition is preferably symmetrical and centered about an axis of symmetry extending parallel to the machine direction. As already mentioned, the area covered by this wide strip of coating composition preferably occupies at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90% of the total area of length covered section (s).

In one additional embodiment of the partial coating, the coating is applied continuously in the axial (transverse) direction, but intermittently in the machine direction , for example in the form of parallel stripes running in the axial direction, that is, from one end of the roll to the other edge, or in the form several covered areas alternating with uncovered areas, as shown, for example, in FIG. 4. In order to determine for this embodiment whether the requirement complies with the invention, it is necessary to calculate the proportion of the total length of the covered areas. For example, if the total length of the continuous web is 20 m, and there are a total of 4 sections, each of which is 2 m long (one of these sections includes the last turn (s) located at the other end), were covered with ( coating composition comprising a non-ionic polymer containing oxygen and / or nitrogen atoms, that is, the first polymer), then in total 40% of the entire length of the continuous web contains the coating composition.

If the coating composition has been applied intermittently in the machine direction, thereby forming two or more coated areas, it is preferred that (i) one coated area includes at least the last turn of the second end. In addition, with regard to the distribution of the coating composition along the length of the continuous web, it is preferable that (ii) the total amount of nonionic polymer applied to the half of the continuous web including the second end is equal to or greater than the total amount of nonionic polymer applied to the half of the continuous web including the first end. In the latter case ("greater than") the difference may be, for example, at least 10%, at least 20%, or at least 50%. According to one aspect of the invention, condition (ii) applies in particular to such embodiments, in which it is not essential whether the continuous web does not include the coating composition over its entire length, but only over a part of it, for example, from 20 to 80%,

In one additional embodiment of the partial coating, the coating is applied intermittently in the machine direction and axial (transverse) direction , for example, in the form of parallel stripes crossing each other. Alternatively, the coating is applied intermittently in the form of dots, as shown in FIG. 6. Dots can form a regular or irregular pattern as a result of, for example, spraying, fiberising or roller coating. In addition, for this embodiment, it is preferred that the area covered by the partial coating occupies at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at at least 90% of the total area of length covered section (s). For example, FIG. 6 shows a partial coating that covers substantially 100% of the length of the continuous web including the coating composition.

One function of the non-ionic polymer ("first polymer") applied to at least 20% of the entire length of the continuous web is to provide the same as resilience. At the same time, if applied to at least the last turn of the second end, the first polymer is also effective in adhering the web of absorbent material of one turn to the web of the adjacent turn (s). This ensures that the second end of the coreless roll is stabilized and that the last winding (s) peeling and flattening is prevented.

Since this function does not necessarily require the use of a non-ionic polymer, it is within the scope of the present invention that at least the last turn located at the second end of the continuous web includes a coating composition that contains an ionic (anionic or cationic) or non-ionic polymer comprising atoms oxygen and / or nitrogen ("second polymer").

2.1. Polymer containing oxygen and / or nitrogen atoms ("second polymer")

The "second polymer" can be selected from ionic (anionic or cationic) or non-ionic polymers.

A) In one embodiment, the coating composition applied to at least the last turn at the second end comprises an ionic polymer comprising oxygen and / or nitrogen atoms. The ionic polymer can be selected from known low tack adhesive polymers suitable for laminating paper webs. The adhesive polymer can be of synthetic or natural origin. Suitable embodiments provide ionic polymers based on polysaccharides, for example polysaccharide derivatives (eg cellulose derivatives) with carboxyl functional groups, such as carboxymethyl cellulose (CMC) or gum arabic. As the coating composition comprising the ionic polymer, commercially available water-based adhesives can be preferably used. They may also contain other additives.

For embodiment (A), it is preferred that the coating composition is applied in less than five turns, more preferably less than three turns, counting from and including the last turn at the second end. In addition, it is preferable that the total amount of coating composition (solids content) per roll is less than 0.05 g, preferably less than 0.03 g.

(B) If a non-ionic polymer is used to cover at least the last turn located at the second end, this non-ionic polymer is preferably the same as used to cover at least 20% of the entire length of the continuous web. In other words, in this preferred embodiment, the second polymer and the first polymer are identical, and preferably the coating composition applied to at least 20% of the total length of the continuous web is identical to the coating composition used to coat at least the last turn at the second end. ...

2.2. Non-ionic polymer containing oxygen and / or nitrogen atoms ("first polymer")

In the present invention, a coating composition comprising a (preferably non-ionic) polymer comprising oxygen and / or nitrogen atoms is applied to at least the last turn located at the second end of the continuous web of absorbent material, and a coating composition comprising a non-ionic polymer comprising oxygen atoms and / or nitrogen is applied to at least 20% of the entire length of the continuous web in the machine direction. When used in a coreless roll with the proper density, the application of a coating composition comprising a non-ionic polymer ("first polymer") to at least 20% of the total length of the absorbent web unexpectedly results in excellent resilience (and thus also adequate flexibility and resilience) but also of sufficient rigidity (and thus also resistance to flattening) and a suitable peeling force. These effects can be further enhanced if the first polymer is also used to coat at least the last turn at the second end of the continuous web. In accordance with the present invention, the preferred polymers used can be described as follows.

Polymers can be classified into two categories, namely ionic polymers and non-ionic polymers. Ionic-type polymers contain substituents that are electrically charged, while non-ionic-type polymers contain electrically neutral substituents. The polymers used in the present invention are preferably of the non-ionic type.

Nonionic polymers as used herein include oxygen and / or nitrogen atoms. Without intending to go into any theory, the non-ionic polymers used here appear to promote adequate electrostatic interactions, in particular the formation of intermolecular hydrogen bonds, for example, hydrogen bonds between a non-ionic polymer and an absorbent material (for example, cellulose fibers), as well as hydrogen bonds between individual molecules of a non-ionic polymer, and intramolecular hydrogen bonds, for example, electrostatic interactions between oxygen and / or nitrogen atoms and hydrogen atoms inside different parts of the same polymer molecule. Moreover, the aforementioned interactions appear to provide the proper stiffness and resilience characteristics while at the same time provide a suitable degree of intersheet adhesion (the degree of electrostatic interactions sufficient to induce reversible intersheet adhesion).

In one embodiment, the non-ionic polymer used herein comprises at least one repeating structural unit containing one or many oxygen atoms and / or one or many nitrogen atoms, for example, from 1 to 5 oxygen atoms and / or from 1 to 5 nitrogen atoms, in particular 1 to 3 oxygen atoms and / or 1 to 3 nitrogen atoms, for example 1 to 3 oxygen atoms. In accordance with the generally accepted understanding of this term, "repeating unit" (also sometimes called "repeating unit" or "monomer unit") refers in particular to one or many parts (blocks) of the polymer, the repeatability of which creates a complete polymer chain in as a result of the binding of repeating structural units to each other sequentially along the chain, with the exception of possible structural modifications in the final groups.

In one additional embodiment, the non-ionic polymer includes at least one repeating structural unit containing one or many oxygen atoms and / or one or many hydroxyl groups.

In one preferred embodiment, on average at least 50%, preferably at least 80% of all repeating units making up the nonionic polymer (and thus the complete polymer chain, excluding end groups) include one or many oxygen atoms, and / or one or many hydroxyl groups and / or one or many amino groups, more preferably one or many ether groups and / or one or many hydroxyl groups.

In one embodiment, the non-ionic polymer exhibits a water solubility at 25 ° C. of at least 40 g / l, preferably 200 g / l, in particular 500 g / l. The solubility of the nonionic polymer in water ensures that the absorbent sheet article of the present invention (in particular, toilet paper, etc.) has good toilet flushing ability. Due to the rather high solubility of the nonionic polymer, it dissolves on contact with water in the sewer system, or at least rapidly forms a dispersion. As a result, clogging of the sewer systems can be effectively prevented. For other versions of the sleeveless roll, which are usually not disposed of through sewer systems, such as sanitary napkins, towels, for example, household towels, tea towels or hand towels, toilet papers, wiping rags and handkerchiefs, this feature is not required, but is preferred.

Also preferred is the use of biodegradable non-ionic polymers.

In the present invention, the amount of nonionic polymer in the coating composition is controlled such that a total amount of 0.001 to 40 g / roll, preferably 0.005 to 10 g / roll, more preferably 0.005 to 5 g / roll, more preferably 0, is applied to the web. 01 to 2 g / roll, more preferably 0.1 to 1.5 g / roll. The amount of non-ionic polymer as used herein is to be understood as the total amount of non-ionic polymer ("first polymer") applied to the continuous web. When the amount of non-ionic polymer applied to the continuous web is less than 0.001 g / roll, the desired properties in terms of stiffness and crumpling resistance cannot be fully achieved. In contrast, when the amount of the nonionic polymer applied to the continuous web is more than 40 g / roll, the roll exhibits high rigidity and resistance to flattening, but manufacturing costs may become high.

In one further preferred embodiment, the non-ionic polymer used herein is a non-ionic cellulose ether, which can be described as follows.

Cellulose ethers are polymers derived from cellulose that are obtained by replacing (in whole or in part) the hydroxyl groups of cellulose. The use of a single esterifying agent (alkylating agent) in the displacement process results in a single cellulose ether, while the use of different types of reactants results in mixed cellulose ethers (mixed ethers). The level of substitution is described as the degree of substitution (DS), defined as the average number of hydroxyl groups substituted per anhydroglucose unit. The DS value can vary between> 0 and 3. If an esterifying (alkylating) reagent such as an alkylene oxide esterifying reagent is used, a new hydroxyl group can be formed and can further react to form oligomeric chains. In this case, the degree of substitution is described as molar substitution (MS), defined as the average number of moles of the esterifying reagent per mole of anhydroglucose unit.

The degree of substitution (DS) and molar substitution (MS) (ionic or non-ionic) cellulose ethers can be determined by methods known in the art, for example, ¹³ C-NMR spectroscopy or Zeisel-GC, as described by the authors. Hodges et al. In Anal. Chem., 1979, Volume 51 (No. 13), pp. 2172-2176.

Cellulose ethers fall into two categories, namely ionic cellulose ethers and nonionic cellulose ethers. Ionic cellulose ethers such as sodium carboxymethyl cellulose (CMC) contain substituents that are electrically charged, while non-ionic cellulose ethers such as methyl cellulose, hydroxypropyl cellulose, etc. contain electrically neutral substituents. The cellulose ethers used in the present invention are of the non-ionic type.

Without wishing to be bound by theory, it is believed that nonionic cellulose ethers provide a finely tunable degree of adhesion between the coating composition and the elongated absorbent material (continuous web). As a result, excellent rigidity and flattening resistance can be achieved, as well as sufficient flexibility and elasticity. In addition, the peel force can be kept within an acceptable range, and thus the elongated absorbent material can be used along its entire length, that is, up to the last sheet.

In accordance with the present invention, the term "nonionic cellulose ether" is to be understood in a broad sense, and includes all types of cellulose ethers - for example, alkyl cellulose ethers, hydroxyalkyl cellulose ethers, alkyl hydroxyalkyl cellulose ethers, and mixed ethers thereof - provided that they are non-ionic.

In one embodiment, the nonionic cellulose ether has a number average molecular weight of 1,000 to 2,000,000, such as 1,000 to 1,000,000, preferably 2,000 to 800,000, such as 2,000 to 500,000, more preferably 3,000 to 200,000, more preferably 5,000 to 100,000 The number average molecular weight of the nonionic cellulose ether used in the present invention can be determined by methods known in the art such as gel permeation chromatography (GPC).

In one further embodiment, the nonionic cellulose ether has a viscosity average molecular weight of 5,000 to 2,000,000, preferably 10,000 to 1,500,000, more preferably 30,000 to 1,000,000. The viscosity average molecular weight of the nonionic cellulose ether used in the present invention can be determined as known in the art. methods such as viscometry.

In one additional embodiment, the nonionic cellulose ether is an alkyl cellulose ether such as methyl cellulose or ethyl cellulose. By "alkyl cellulose ether" we mean a (non-ionic) cellulose ether in which some of the hydroxyl groups of the cellulose (at least one hydroxyl group in one individual anhydroglucose unit) are substituted with an alkyl group, i.e. a linear or branched alkyl group having from 1 to 20 carbon atoms, preferably from 1 to 12 carbon atoms, more preferably from 1 to 6 carbon atoms, in particular a methyl group, an ethyl group or a propyl group. In addition, the expression "alkyl cellulose ether" in accordance with the present invention is intended to include cellulose ethers such as methyl cellulose or ethyl cellulose, as well as mixed ethers thereof such as hydroxyalkyl methyl celluloses, for example hydroxyethyl methyl cellulose.

In one further embodiment, the nonionic cellulose ether is an alkyl cellulose ether selected from methyl cellulose (MC), mixed MC ethers such as hydroxyethyl methyl cellulose (HEMC), hydroxypropyl methyl cellulose (HPMC) and hydroxybutyl methyl cellulose (HBMC), ethyl cellulose (EC), mixed ethers EC such as hydroxyethylethylcellulose (HEEC), hydroxypropylethylcellulose (HPEC) and hydroxybutylethylcellulose (HBEC). The cellulose ether is preferably MC, EC, or HPMC, more preferably MC or EC.

MC, as preferably used herein, may have a DS of 1.4 to 2.4, preferably 1.6 to 2.0. HEMC, as preferably used herein, may have (methyl) DS from 1.3 to 2.2, and (hydroxyalkyl) MS from 0.06 to 0.5. HPMC, as preferably used herein, may have a DS of 1.1 to 2.0 and an MS of 0.1 to 1.0. HBMC, as preferably used herein, typically has a DS of greater than 1.9 and at most 2.4 and an MS of greater than 0.04 and at most 0.6. EC, as preferably used herein, may have (ethyl) DS from 1.0 to 2.5, preferably DS from 1.1 to 1.5.

In another preferred embodiment, the nonionic cellulose ether is a hydroxyalkyl cellulose ether such as hydroxyethyl cellulose or hydroxypropyl cellulose. As used herein, "hydroxyalkyl cellulose ether" means a (non-ionic) cellulose ether in which some of the hydroxyl groups of the cellulose are replaced by a hydroxyalkyl group, for example, a linear or branched hydroxyalkyl group having from 1 to 20 carbon atoms, preferably from 1 to 12 atoms carbon, more preferably 1 to 6 carbon atoms such as (2-hydroxy) propyl group or hydroxyethyl group.

In one preferred embodiment, the nonionic cellulose ether is an ether of hydroxyalkyl cellulose selected from hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and hydroxybutyl cellulose (HBC). The hydroxyalkyl cellulose ether is preferably HEC or HPC, more preferably HPC. HEC as used herein can have an MS of 0.1 to 3.6, preferably 1.5 to 3.5. HPC as used herein can have an MS of 1.0 to 3.8, preferably 2.0 to 3.6.

The definition of "nonionic cellulose ether" in accordance with the present invention also includes a mixture (combination) of at least two, for example 2, 3 or 4, different nonionic cellulose ethers, in particular a mixture of an alkyl cellulose ether and a hydroxyalkyl cellulose ether such as a mixture of MC and HPC.

In one further embodiment, the coating composition comprises one or more “nonionic cellulose ethers” as the sole nonionic polymer (s), and in particular does not contain hydroxyl-terminated polyether, and / or does not contain other saccharides than nonionic cellulose ether.

In one other preferred embodiment, the non-ionic polymer used herein is a hydroxyl-terminated polyether selected from polyethylene glycol, polypropylene glycol, and mixtures thereof, more preferably polyethylene glycol.

In one embodiment, the polymer has a number average molecular weight of 800 to 250,000, preferably 1,000 to 50,000, more preferably 1,500 to 15,000, more preferably 1,500 to 10,000, more preferably 2,000 to 7,500, such as 2,500 to 4,000.

In one preferred embodiment, the polymer is a polyethylene glycol having a number average molecular weight of 800 to 250,000, preferably 1,000 to 20,000, more preferably 1,500 to 10,000, more preferably 2,000 to 7,500, more preferably 2,500 to 6,500, even more preferably from 2500 to 4000.

The number average molecular weight of the polymer used in the present invention can be determined by methods known in the art such as gel permeation chromatography (GPC).

In another embodiment, the polymer used in the present invention is described by the following formula (I):

wherein, in the above formula, n is an integer having an average value of 10 to 5000, preferably 10 to 2500, more preferably 20 to 1000, more preferably 30 to 200, more preferably 50 to 150, or 50 to 100. Preferably n is an integer having an absolute value of 10 to 5000, preferably 10 to 2500, more preferably 20 to 1000, more preferably 30 to 200, more preferably 50 to 150, or 50 to 100.

2.3. Additives

Plasticizer

The coating composition according to the present invention may include a plasticizer, for example, a known ester-type plasticizer. The plasticizer can improve the film-forming properties of the coating composition. It is selected to be compatible with the above-described polymer. In one embodiment, the coating composition of the present invention does not contain a plasticizer.

One type of plasticizer by itself can be used, or two or more types can be used in combination.

For reasons of stability over time, the content of the plasticizer in the coating composition according to the present invention is preferably not more than 20% by weight of the total solids concentration, more preferably not more than 10% by weight, even more preferably not more than 5% by weight.

Hardening agent

The coating composition according to the present invention may include a toughening agent.

In one embodiment, the coating composition according to the present invention does not contain hardening chemical additives such as stable resins, for example free of the water-soluble cationic or anionic polymers described below. When the coating composition includes a hardening agent, a water-soluble cationic polymer and / or a water-soluble anionic polymer as known in the art can be used.

Other additives

The composition according to the present invention may contain known additives of suitable various types, as long as this does not interfere with the manifestation of the effects of the present invention. Examples include perfume, coloring agent, surfactant, decalcifier, and antibacterial agent, as well as inorganic or organic fillers.

One type can be used alone, or two or more types can be used in combination.

3. Absorbent product used for coreless roll

The coreless roll of the present invention has many applications in the area of sanitary and hygienic or household absorbent articles. In particular, the roll of the present invention can be an absorbent sheet product selected from the group consisting of sanitary napkins, towels such as tea or hand towels, toilet paper, wiping papers, and facial tissues.

In the present invention, the absorbent sheet product is in the form of a continuous web of absorbent material having a first end and a second end, which consists of at least one layer of tissue paper base with a typical basis weight of 8 to 60 g / m ² , preferably 10 up to 30 g / m ² .

In one embodiment, the continuous web of absorbent material is a single layer tissue made from tissue paper or a multi-layer sheet formed from, for example, 2-5 layers of tissue paper overlaid on top of each other. To obtain a multilayer absorbent sheet product, single-layer base tissue papers are combined in a processing step to a final number of layers, which may be, for example, from 2 to 5, depending on the desired properties of the final product. The total basis weight of the resulting multi-layer web is preferably not more than 120 g / m ² , and more preferably below 65 g / m ² , for example below 55 g / m ² .

In the present invention, the second end of the continuous web is coated with a coating composition of the present invention (i.e., a composition comprising a polymer as described above) and is spirally wound to form a roll of absorbent sheet product such as a roll of toilet paper. The coating composition can be applied to the second end using methods known in the art. These common methods include "spraying" and "roller coating".

In the present invention, the coating composition is applied to at least one of two sides of the continuous web, that is, the top and / or bottom side of the longitudinally continuous web, or between the web-forming layers of tissue base paper.

When the web is a multi-layer web, for example a web having 2 to 5 layers of tissue paper superimposed on one another, the coating composition can be applied to one or both sides of one or more layers, for example all layers. In one embodiment, the coating composition is applied to one of the outer layers of the web, preferably the outer layer that faces the axial hollow opening (ie, the outer layer, which is the layer closest to the axial hollow opening). The outer layer can be coated on one or both sides, preferably on its lower side, that is, on the side facing the axial hollow opening.

The absorbent sheet product according to the present invention is preferably selected from sanitary napkins, towels such as tea or hand towels, toilet paper, wiping papers, and facial tissues. By "toilet paper" we mean a soft and strong tissue base paper that is used to clean the buttocks after using the toilet (sometimes also called "paper towel").

The present invention also relates to the use of the coreless roll as toilet paper, household towel, tea towel, wiping paper, napkin or handkerchief.

According to one preferred embodiment, the absorbent sheet product is a toilet paper composed of 2-5 layers of tissue paper overlapping each other, for example 2 to 4 layers of tissue paper, in which the coating composition is applied to at least one outer layer of continuous web, preferably on the underside of the outer layer closest to the axial hollow opening.

The dimensions of the coreless roll according to the present invention are not limited, and are highly dependent on the target absorbent sheet product. For example, an individual roll can have a diameter (edge diameter) of 5 cm to 50 cm, preferably 8 cm to 20 cm (eg, 100 mm to 155 mm). The axial hollow opening may have a diameter of 10 mm to 70 mm, preferably 20 to 50 mm. The width of the roll (i.e., the distance between one edge and another edge) can be in the range of 60 mm to 800 mm, preferably 70 mm to 400 mm, for example 80 mm to 150 mm.

The continuous web of absorbent material forming the absorbent sheet product preferably has an overall MD length of 1 m to 60 m, preferably 1.5 m to 50 m, such as 2 m to 40 m. Optionally, the web may be partially cut in the machine direction so that it consists of successive single, but linked sheets. A single sheet may have a length (machine direction) of 80 mm to 300 mm, for example 100 mm to 250 mm, in particular 100 mm to 200 mm.

One additional and preferred embodiment (of the present invention) can be described as follows:

a coreless roll of absorbent sheet product made of a spirally wound continuous web of absorbent material having a first end and a second end, the absorbent material web being wound so as to create an axial hollow opening positioned centrally relative to the coreless roll and extending from one edge to the other edge of the coreless the roll, and so that the first end is on the outside of the roll, and the second end is at the axial hollow opening;

moreover, the spirally wound continuous web of absorbent material has a density of from 60 to 130 mg / cm ³ , preferably from 70 to 120 mg / cm ³ ;

wherein at least the last two turns located at the second end of the continuous web of absorbent material, preferably at least the last three turns, more preferably at least the last five turns, comprise a coating composition comprising a non-ionic cellulose ether (as a non-ionic polymer), preferably an alkyl cellulose ether such as methyl cellulose or ethyl cellulose, a hydroxyalkyl cellulose ether such as hydroxyethyl cellulose or hydroxypropyl cellulose, or a combination thereof; and

wherein at least 40%, for example 40 to 90%, or 50 to 80%, of the total length of the continuous web of absorbent material in the machine direction comprises said cover composition comprising said non-ionic polymer, in which:

a. the maximum intersheet adhesion between the coated portions of the continuous web of absorbent material and the portions of the continuous web in contact with them is preferably 0.4 to 1.5 N, for example 0.5 to 1.2 N, and / or

b. wherein the coating composition is preferably applied such that, with respect to the length or lengths of the continuous web comprising the coating composition, the area covered by the coating composition preferably occupies at least 50%, more preferably at least 60%, more preferably at least 70 %, more preferably at least 80%, more preferably at least 90%, of the total area of said section (s) of length, and / or

With. if the coating composition has been applied continuously in the machine direction, the formed coated area preferably begins at the second end and includes at least the last turn of the second end, and if the coating composition has been applied intermittently in the machine direction, thereby creating two or more coated areas, (i ) one coated area includes at least the last turn of the second end, and (ii) the amount of nonionic polymer applied to the half of the continuous web, including the second end, is preferably equal to or greater than the amount of nonionic polymer applied to the half of the continuous web, including the first the end; and / or,

d. the amount of nonionic polymer is 0.01 to 2 g / roll, preferably 0.1 to 1.5 g / roll; and / or,

e. preferably has a diameter (edge diameter) of 8 cm to 20 cm (eg, 100 mm to 155 mm); and / or,

f. the coating composition is free of hydroxyl-terminated polyether and / or contains no saccharides other than nonionic cellulose ether.

In one additional embodiment, the linerless roll includes all of features (a.) To (f.). It should be noted that where the present disclosure mentions that the features in the above feature combination may be replaced by wider or narrower ranges or wider or narrower terms / definitions, this results in additional embodiments of the present invention.

4. A method of manufacturing sleeveless rolls and absorbent products

The present invention also relates to a method for making a coreless roll as described above and below, the method comprising:

(A) moving a continuous web of absorbent material having a first end and a second end, which is preferably constituted by one layer of tissue paper, or 2 to 5 superimposed layers of tissue paper;

(B) applying a coating composition comprising a (preferably non-ionic) polymer containing oxygen and / or nitrogen atoms to at least the last turn located at the second end of the continuous web, and applying a coating composition comprising a non-ionic polymer containing oxygen atoms and / or nitrogen for at least 20% of the entire length of the continuous web in the machine direction; moreover, the coating composition applied to the last turn (s) is preferably the same as applied to at least 20% of the entire length of the web;

(C) spirally winding a continuous web of absorbent material so as to form a log of the absorbent material web, the absorbent material web being wound so as to define an axial hollow opening positioned in the center of the log and extending from one edge of the log to the other edge of the log, and so, that the first end is on the outside of the log and the second end is at the axial hollow opening;

(D) optionally cutting the continuous web of absorbent material substantially cross-machine direction to provide single but interlocked sheets;

(E) cutting the log into multiple caseless rolls.

According to one embodiment of the present invention, the above method for making a coreless roll further comprises:

(F) subjecting the linerless roll to compression in a direction perpendicular to the axial hollow opening to obtain a linerless roll in a compressed form.

The coreless roll of the present invention can be made using a commercially available paper converting machine. A suitable paper converting machine can be purchased, for example, from Paper Converting Machine Company (PCMC), Europe.

The description of the method below with reference to the modules / sections of the machine is to be understood as illustrating a machine suitable for making a roll according to the present invention. It is also possible to use machines / sections of other types known in the art.

In the present invention, with reference to FIG. 5 and 6, a method for manufacturing a tubeless roll includes the steps:

(A) moving a continuous web (19) of absorbent material having a first end and a second end.

The continuous web (19) of absorbent material used in the present invention is composed of one or more layers of tissue base paper having a basis weight of 8 to 60 g / m ² , preferably 10 to 30 g / m ² . Base tissue paper is typically produced in large original rolls (15) and (16) machine winding for subsequent rewinding and cutting, having a width of 1.80 m to 7 m, as obtained from a tissue machine. The original rolls (15) and (16) of the machine winding are installed on the unwinding stacks (10) and (11) of the paper processing machine (9). The number of machine wound initial rolls used corresponds to the number of layers in the target absorbent sheet product. In FIG. 5 and 6, two original machine-wound rolls (15) and (16), each of which feeds one layer of paper towel (18A) and (18B) are used to obtain a roll (1) of two-layer toilet paper.

Layers (18A) and (18B) are fed from unwinding jigs (10) and (11) to an embossing section (12), in which the layers are superimposed and combined (bonded) to form a continuous web (19) of absorbent material.

The embossing section includes an engraved cylinder (20) and a mating rubber cylinder (21), both rotating in opposite directions, and optionally an adhesive dispenser (not shown). The engraved cylinder can be engraved with a micro-structural pattern that combines a variety of embossed points. The engraved cylinder can emboss one or two levels in overlapping layers.

The glue dispenser, if present, typically includes a bath (glue reservoir), an applicator barrel, and an immersion cylinder. The applicator cylinder presses the stacked tissue paper layers against the engraved cylinder. A dip cylinder (not shown) picks up the adhesive in the bath and transfers the adhesive to an applicator barrel (not shown). The applicator cylinder is designed to apply a specific pressure to the engraved cylinder on the peripheral region of the embossing projections. At this specified pressure, the adhesive passes through the web and bonds the layers. The amount of adhesive used for bonding the layers is preferably 0.1 g / m ² to 5.0 g / m ² , preferably 0.2 g / m ² to 1.0 g / m ² . An example of a suitable adhesive for bonding layers is Swift®tak 1004 from HB Fuller, Europe.

The above-described embossing step is used to combine layers of tissue base paper, and also to emboss or micro-emboss at least one of the layers to create aesthetic effects or modify the thickness, softness, or pliability of the resulting continuous web (19).

(B) Applying a coating composition to at least the last turn located at the second end of the continuous web and applying a coating composition to at least 20% of the total length of the continuous web, the coating composition that is applied to the last turn (- ki) is preferably the same as applied over at least 20% of the entire length of the web to form a solid or partial coating. The coating composition (s) are (are) applied to a continuous web (including the last turn (s)) by methods known in the art. In the present invention, among other methods, it is possible to use spraying, controlled fiberization or roller coating.

"Spraying" as used herein means that the coating composition (s) are applied to a continuous web in the form of a dispersion of fine liquid droplets in a gas (ie, a spray). Sprays are usually formed using a spray nozzle (spray gun) that has a fluid channel that is operated by mechanical forces that spray the fluid. Liquid droplets can have a size of 1 micron to 1000 microns, for example, from 10 microns to 400 microns.

The paper converting machine (9) can be equipped with one or many spray guns (23A), for example, from 1 to 8 spray guns, which can be placed in any position of the processing line, as far as is rational from the standpoint of the desired results (coating on the second end). The spray (s) (23A) may (s) be placed (s) in front of the embossing section (12) so that the coating composition (22) is applied, for example, to the outer layer or between the layers. The atomizer (s) (23A) is preferably positioned between the cutting unit (27) and the winding unit (28) such that the coating composition (s) are applied to the underside of the outer layer (as shown in FIG. . 7).

The spray system includes one or more spray guns (23A), a bath (24), and conduits (25) feeding the coating composition (22) from the bath to the spray gun (s) (23A). The spray system is optionally equipped with a heating system (e.g., a heating jacket, heat gun, etc., not shown) that heats the coating composition in a bath (24), conduits (25) and / or atomizer (s) (23A) so as to maintain the composition in a liquid state during spraying. In particular, the heating system can heat the coating composition at a temperature above the melting point of the polymer used in the composition.

Sprayers suitable for spraying the coating composition (s) according to the present invention can be obtained, for example, from Walther Spritz- und Lackiersysteme GmbH, Germany.

"Controlled fiberization" as used herein means that the coating composition (s) are applied to a continuous web in the form of strands (fine filaments) forming a controlled or random pattern, for example by means of swirling effects. Adjustable or randomly patterned strands are typically formed using a spray applicator in which multiple jets of air work together to fiberize the stream of coating composition exiting the spray nozzles. Spray applicator (s) suitable for applying the coating composition of the present invention can be purchased, for example, from ITW Dynatec® GmbH, Germany.

"Roller coating" as used herein means that the coating composition (s) are applied directly to a continuous web using a roll roller. "Roll-to-roll coating" and "reverse roller coating" refer to well-known methods that can be used in the present invention. With reference to FIG. 8, the roller coating system includes a dip cylinder and applicator cylinders (23B), a bath (24), and conduits (25) feeding the coating composition (22) from the bath to the dip cylinder and applicator cylinders (23B). The roller coating system optionally includes a heating system as described above (not shown). The roller coater can be positioned, for example, on the embossing section such that the applicator cylinder (23B) is pressed against the engraved cylinder (20) or another cylinder (as shown in FIG. 8).

The spray gun (s) (23A) or roller coater (23B) can be adjusted for continuous coating in the machine and axial directions, or intermittent coating (e.g. strips, dots, etc.) in the machine and / or axial direction.

In some aspects of the present invention, the coating composition applied to at least the last turn located at the second end of the continuous web, and the coating composition applied to at least 20% of the total length of the web, can be applied using different methods (if different cover compositions). For example, a coating composition applied to at least the last turn (s) can be applied using a coater, while a coating composition applied to at least 20% of the total length of the web can be applied spraying.

(C) Spiral winding of the continuous web (19) to form a log (34) of the web of absorbent material.

The continuous web (19) is fed from the embossing section (12) to the rewinding section (13), in which the web (19) is spirally wound to form a log (34) of the web of absorbent material. The rewinding section (13) includes a perforating module (26), a cutting module (27), a winding module (28) and an extraction module (33). The rewinding section (13) winds a continuous web (19) with the formation of multiple logs (34).

The winding module (28) is intended for winding a continuous web with the formation of web logs (34). The winding module (28) can be of peripheral type (axially wound) or surface type (surface wound). The winding module includes a roller table (29), a first winding roller (30), a second winding roller (31), a third winding roller (32), and a temporary sleeve feeding device (not shown). The log is formed by winding a continuous web onto a temporary sleeve (36) that supports a well-defined axial hollow opening. Temporary sleeves (36) are sequentially fed by the temporary sleeve feeding device through the roller table (29) before the start of a new cycle of log formation. The temporary sleeve (36) can be made, for example, of plastic or cardboard. To grip the second end of the web (19) onto the temporary sleeve (36) at the start of a new production cycle, a “flying glue” (sticking glue) can be used.

The log (34) is held in position during winding by the first, second and third winding rollers (30), (31) and (32) rotating in surface contact with the log (34). One of the winding rollers (30), (31) and (32) can set the rotary motion of the log (surface winding).

Once the desired log diameter is reached (corresponding mainly to a certain web length or number of individual sheets), the continuous web (19) is cut. The received log (34) is separated from the canvas (19), and then the production of a new log begins.

Section (27) cutting is designed to cut the web according to regularly spaced from each other cutting lines, essentially transverse to the machine direction. The cutting of the web is carried out in a transitional phase, namely, when the formation of the first log ends at the end of the log production cycle, and before the start of winding the second subsequent log at the beginning of a new log formation cycle.

Cut lines (not shown) are axial lines drawn across the thickness of the blade (19). Two successive cutting lines define the total length of the blade forming one roll. The distance between two successive cutting lines, that is, the length of the roll, is determined depending on the target product. Typically, the length of the roll and the diameter of the roll are selected depending, for example, on the number of layers forming the web, the basis weight of the individual layers, etc. A single roll of absorbent sheet product may have an overall MD web length of 1 m to 60 m, preferably 1.5 m to 50 m, for example 2 m to 40 m.

The resulting log (34) is then fed to the extraction module (33), which is designed to pull the temporary sleeves (36) out of the log (34) after the log winding is complete. The temporary sleeves (36), after removal, can be reused using the sleeve feeder.

When the coating composition used in the method of the present invention is an aqueous solution as described herein above, the resulting log can be dried. The resulting log is then separated from the web of absorbent material to remove the temporary sleeve. The resulting log can also be dried after removing the temporary sleeve.

The resulting log is preferably dried until the sanitary paper forming the log contains an amount of water that does not exceed 10% of the total weight of the log, preferably 5% of the total weight of the log. For example, the resulting log can be dried by keeping the log at room temperature (20 ° C to 25 ° C) and an RH (relative humidity) of 10 to 60% for a period of 12 hours.

(D) Optionally cutting the continuous web (19) of absorbent material substantially cross-machine direction to produce single but interlocked sheets.

Before the continuous web (19) is spirally wound in the winding module (29), as described above, the web (19) enters the perforating module (26), if any, which is designed to create a web (19) with regularly spaced spacing from each other by perforation lines (8), substantially transverse to the machine direction, that is, in the axial direction, to form single but interlocking sheets (as shown in Figures 3, 4a and 4b).

The perforation line (8) is a line in the axial direction formed through the thickness of the web (19) and includes alternating perforated segments and non-perforated segments (i.e., two perforated segments are separated by one non-perforated segment, and vice versa). Each non-perforated segment forms a connection zone between two successive sections of a continuous web. Each perforated segment forms a separation zone between two successive sections of a continuous web. When considering the width of the individual roll, for example, between 10 cm and 30 cm, the length of said non-perforated / perforated segments can be from 1 mm to 15 mm, preferably from 4 mm to 10 mm. Other types of perforation lines are also possible, as far as is essential.

Two successive perforation lines (8) define the length of the individual sheet in the finished absorbent sheet product. The distance between two successive perforation lines, that is, the length of the sheet, is determined depending on the target product. A single sheet can have a machine direction length of 80 mm to 300 mm, for example, 100 mm to 250 mm. For example, a paper towel sheet can be 80 mm to 200 mm long, and a towel such as a household (kitchen) towel or hand towel can be 80 mm to 300 mm long.

(E) Cutting the resulting log (34) into multiple caseless rolls (1).

After winding, the log (34) is fed to a log cutting section (14), in which the log (34) is cut parallel to the machine direction using multiple chopping saws (35) into multiple individual rolls (1). Numerous chopping saws (35) are spaced at regular axial distances from each other so that the log (34) is cut into multiple individual rolls (1) having a defined axial width (i.e., the distance from one edge to the other edge) ... The width of the individual roll (1) is 60 mm to 800 mm, preferably 70 mm to 400 mm, for example 80 mm to 150 mm.

The control module (37) is connected to the winding module (28), to the perforating module (26), to the cutting module (27) and to the spraying, fiberizing or roller coating system via the interface (38). The control module (37) controls the operation of the winding module (28), the perforating module (26) and the cutting module (27). In particular, the control module (37) controls the forces applied to the continuous web during the winding process (thereby making it possible to achieve the desired roll density), activates the cutting module (27) to cut the web (19) in a transition phase between two successive logs, and controls the operation of the perforating module (26) outside the transition phases.

In addition, the control module (37) controls the operation of the spraying, fiberizing or roll-coating system, namely, the proper application (spraying, fiberizing or roll-coating) of the coating composition to the second end of the continuous web (19).

The proper application of the coating composition to the second end can be controlled by transmitting, for example, start / stop signals to the application system, which are determined based on the length of the target article and machine parameters such as operating speed.

The various rollers (17) are properly positioned to control the path of the continuous web (19) along the paper processing machine (9), within and between the various sections.

(F) Optional subjecting the roll to compression in a direction perpendicular to the axial hollow opening to obtain a linerless roll in a compressed (oval) shape (not shown).

As used herein, "squeezing" means that pressure is applied to the roll in a direction perpendicular to the axial hollow opening to produce a roll having an oval cross-section that requires less storage space. Compression of the roll is preferably performed immediately after winding is completed. A suitable device known in the art can be used to perform the compression. In the present invention, it is possible to use, for example, two converging synchronously moving conveyor belts described in patent document WO 95/13183, a pneumatically or hydraulically driven pressure plate or other devices.

Thereafter, the individual tubeless rolls (1) are packed and prepared for shipment (not shown).

5. Examples

The following test methods were used to evaluate the absorbent materials, polymers and the resulting coreless rolls.

5.1. Base weight

The basis weight was determined according to EN ISO 12625-6: 2005, Tissue Paper and Tissue Products, Part 6: Determination of grammage.

5.2. Thickness

The measurement is carried out with a precision micrometer (accuracy 0.001 mm) according to a modified method based on EN ISO 12625-3: 2014, Part 3. For this purpose, measure the distance created between the fixed reference plate and the parallel pressure arm. The diameter of the pressure arm is 35.7 ± 0.1 mm (10.0 cm ² nominal area). The applied pressure is 2.0 kPa ± 0.1 kPa. The pressure lever can be moved at a speed of 2.0 ± 0.2 mm / s.

A suitable device is a thickness gauge type L&W SE050 (manufactured by Lorentzen & Wettre, Europe).

The tissue article to be measured is cut into 20 x 25 cm pieces and conditioned in an atmosphere of 23 ° C, 50% RH (relative humidity) for at least 12 hours.

For measurement, one sheet is placed under a pressure plate, which is then lowered. The sheet thickness is then read 5 seconds after the pressure has been stabilized. The thickness measurement is then repeated nine times with additional samples processed in the same way.

The average of the 10 values obtained is taken as the thickness of one sheet ("thickness of one sheet") of the measured tissue paper (for example, three-layer toilet paper).

5.3. Number average molecular weight

Measurement is performed by gel permeation chromatography (GPC) using a PL-GPC 50 combined GPC / SEC system equipped with a PL aquagel-OH MIXED column, 8 μm particles, 7.5 x 300 mm (both from Agilent Technologies, Europe). The GPC system was calibrated using a pullulan polysaccharide calibration kit from Agilent Technologies (for methyl cellulose), or, depending on the polymer being measured, a suitable calibration kit such as a hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose calibration kit, all from American Polymer Standards Corporation , or the PEG-10 EasiVial calibration kit from Agilent Technologies.

A sample of the polymer to be measured was dissolved in water at a concentration of 2 mg / ml. The sample was injected (injection volume: 100 μl), and measurement was performed at a flow rate of 1.0 ml / min and a temperature of 50 ° C using an aqueous buffer solution of 0.05 M NaH ₂ PO ₄ , 0.25 M NaCl, pH 7 (for cellulose ethers) or water (for hydroxyl-terminated polyethers) as eluent. The retention time (minutes) of the polymer was recorded as a peak. The number average molecular weight of the polymer was determined by comparing the recorded retention time with the value for standard (calibration) polymers.

5.4. Viscosity average molecular weight

The measurement can be carried out as follows by viscometry using an Ubbelodhe capillary viscometer equipped with a capillary having an inner diameter of 0.63 mm (both from SI Analytics, Europe).

A solution of a sample (concentration C ₁ = 10.0 g / l) of polymer in water is obtained and transferred to an Ubbelodhe capillary viscometer. The viscometer is suspended in a thermostated bath for 30 minutes at a temperature of (25 ± 0.1) ° C. The flow time (the time taken for the sample solution to flow between the two calibration marks) is measured. The measurement is repeated five times, and the average of the five values obtained is taken as the flow time of the sample solution. The same measurement is reproduced with a water sample (no cellulose ether). The Hagenbach correction factor was subtracted from the measured flow times (as indicated by SI Analytics).

The relative viscosity z ₁ of a cellulose ether sample can be calculated as follows:

z ₁ = (flow time of sample solution) / (flow time of water)

The measurement is repeated using additional sample solutions with concentrations of C ₂ = 5.0 g / L, C ₃ = 3.33 g / L and C ₄ = 2.5 g / L. Get the relative viscosities z ₂ , z ₃ and z ₄ .

The intrinsic viscosity η can be determined graphically by plotting the relative viscosity (y-axis) versus sample concentration (x-axis), and extrapolating the theoretical straight line back to zero concentration (the line intersects the y-axis at the height of the intrinsic viscosity).

The viscosity average molecular weight M̅v of cellulose ether can be calculated using the Mark-Houwink-Sakurada equation (1) and the cellulose ether K and α constants as shown by Brandrup, J., Immergut, EH, Grulke, EA, Polymer Handbook , 4th edition, John Wiley & Sons, New York, 1999 (hydroxyethyl cellulose: K = 9.53⋅10 ^-3 ml / g, α = 0.87).

(1)

(one)

5.5. Density

The measurement of the density of the rolls was carried out as follows: the dimensions of the measured roll were obtained, including the outer diameter D, the diameter d of the axial hollow opening and the width h. Determined the weight M of the roll. The density δ of the roll was calculated using the following equation:

5.6. Axial stiffness

The measurement was carried out using a vertical dynamometer equipped with a 2.5 kN cell. A suitable instrument is a dynamometer of the type ZwickiLine Z1.0 (from Zwick Roell, Europe).

The roll was placed vertically between pressure plates (one of the two flat edges), and pressure was applied in a direction parallel to the axis of the hollow opening. The roll was compressed between the plates at a constant speed of 60 mm / min. The compressive force was measured and plotted against the cell displacement (y-axis: compressive force; x-axis: cell displacement). The correlation between the compressive force and the displacement of the cell was determined by linear regression in the area of elastic deformations on the graph. The slope of the linear regression was taken as the axial stiffness of the roll.

The measurement was repeated four times with additional samples (rolls of toilet paper from the same production batch), and the average of the five values obtained was taken as the axial stiffness K _{ax of the} roll.

5.7. Radial stiffness

The measurement is carried out using a vertical dynamometer (ZwickiLine Z1.0) equipped with a 200 N cell.

The roll was placed horizontally between the pressure plates (on the round edge), and pressure was applied perpendicular to the axis of the hollow opening. The roll was compressed between the plates at a constant speed of 60 mm / min. The compressive force was measured and plotted against the cell displacement (y-axis: compressive force; x-axis: cell displacement). The correlation between the compressive force and the displacement of the cell was determined by linear regression in the area of elastic deformations on the graph. The slope of the linear regression was taken as the radial stiffness of the roll.

The measurement was repeated four times with additional samples (rolls of toilet paper from the same production batch), and the average of the five values obtained was taken as the axial stiffness K _{rad of the} roll.

5.8. Elasticity

The measurement is carried out using a vertical dynamometer (ZwickiLine Z1.0) equipped with a 2.5 kN cell.

The roll was placed horizontally between pressure plates (dimensions: 190 × 190 × 15 mm) and the top plate was lowered until the detected force reached (0 ± 0.1) N. The distance between the two pressure plates (corresponding to the outer diameter of the roll) was measured, and taken as the original height H (i) of the roll.

Applied pressure and, at the same time, turned on the timer (t = 0 sec.). The roll was compressed between pressure plates at a constant speed of 400 mm / min until a maximum force of 10 N was reached. The distance (i.e., roll height) between the two pressure plates after reaching a maximum force of 10 N was measured and taken as H (10N). The pressure was released so that the pressure plates could return to their original position at a speed of 800 mm / min.

At a time point of 30 seconds, the roll height H (30s) was measured.

The roll elasticity R was calculated using the following equation:

The elasticity measurement was repeated four times with additional samples, and the average of the five values obtained was taken as the measured roll elasticity.

5.9. Inter-sheet adhesion (peeling force)

The measurement is carried out using a vertical dynamometer (39) (ZwickiLine Z1.0) equipped with a set of shafts (40) - (43), a clamp (45) and a 50 N cell (not shown) as shown in FIG. 9a, 9b and 9c.

For the measurement, the first inner turns of the coreless roll (44) to be measured were slid onto the upper roll (41) of the roll set, the outermost paper sheet was unwound and placed on the roll set as shown in FIG. 9a and the outermost paper sheet was inserted into the clamp (45). The coils were unwound at a constant speed of 300 mm / min. The peel force required to separate the roll-forming paper sheets was measured and plotted as a function of cell displacement. The maximum force and the average force required to delaminate the sample were recorded within the displacement interval. The peel force measurement was then repeated four times on additional samples.

The average of the 5 values of the maximum force obtained is taken as the peeling force of the coated continuous web.

5.10. Charge requirement

The measurement can be carried out as follows by polyelectrolytic titration using a PCD 03 pH particle charge detector manufactured by BTG Mütek GmbH, Germany.

A solution of the polymer sample in water (eg 0.1 wt%) is prepared and transferred to a particle charge detector. Monitor the current flowing through the sample solution and add a titrant (polyDADMAC, 0.001N) until the zero charge point is reached (i.e., measured current flow = 0 mV). The specific amount q of electricity (ionic demand in [eq / g]) can be calculated using the following equation:

in which V [L] represents the consumed volume of titrant (polyDADMAC), c [eq / L] represents the concentration of the titrant, and m [g] represents the amount of polymer in the sample solution.

5.11. Disintegrability

Disintegrability (degradability) can be determined according to NF Q34-20: 1998, Sanitary and Domestic Articles - Bathroom Tissue - Determination of Disintegration.

5.12. Flattening

The test can be carried out using a vertical dynamometer (ZwickiLine Z1.0) equipped with a 1 kN cell.

The roll is placed horizontally (on the round edge) between the pressure plates. The roll is compressed between pressure plates at a constant speed of 400 mm / min until an oval cross-sectional shape is achieved, that is, the axial hollow opening becomes invisible. The roll is held in a compressed form for about 10 seconds and the pressure is released so that the pressure plates can return to their original position at a speed of 800 mm / min. The compression cycle is repeated 4 times.

The test is repeated four times with additional samples (rolls of toilet paper from the same production batch). The flattening of the sample roll is assessed by visual inspection of the first inner turns forming the newly opened axial hollow opening.

Hereinafter, flattening = "yes" means that delamination of the first inner windings in the newly opened axial hollow opening can be detected in at least one of the 5 roll samples tested. Flattening = no means that peeling of the first inner windings cannot be detected in all 5 roll samples tested, that is, the newly opened axial hollow opening is well defined and the roll can be easily placed on the roll holder shaft.

5.13. Raw materials, chemicals and paper converting machine

Absorbent material

A three-layer tissue paper (standard) having a basis weight of 55.6 g / m ² and a thickness of 0.62 mm (manufactured by SCA) was used as a continuous web of absorbent material in Control Examples 1-3, Examples 1-7 and Comparative Examples 1-4.

A three-ply tissue paper (continuous web) was prepared using a standard converting machine by combining a single-ply tissue paper to form a finite number (3) of layers as follows.

The first unwinding section feeds the first layer of tissue paper from a first machine-wound initial roll having a width of 0.6 m. The second unwinding section feeds a second layer of tissue paper from a second machine-wound initial roll having a width of 0.6 m. the section feeds the third layer of tissue paper from a third machine wound original roll having a width of 0.6 m. The layers of tissue paper are fed into the embossing section. Sanitary papers are layered on top of each other and combined (bonded) using glue in the embossing section to form a continuous web of absorbent material. The engraved cylinder performs a two-level embossing in the log from superimposed absorbent base webs. The adhesive used to bond the layers was Swift®tak 1004 at 0.5 g / m ² .

The resulting three-layer continuous web of absorbent material was fed into a rewinding section.

Chemicals

The following are the chemicals used in the following examples:

- for the cover composition:

> hydroxypropyl methylcellulose from Sigma-Aldrich with a hydroxypropyl group content of about 9% and a viscosity of about 15 cP (2% solution in water at 25 ° C).

- adhesive materials:

> Swift®tak 1004 from H.B. Fuller (used to bond layers);

> Tissue Tak 604 from Henkel (fly glue used for winding).

Paper converting machine

A standard tissue paper machine has been adapted to make toilet paper having three layers. The machine included two unwinding sections, an embossing section, a rewinding section and a log cutting section.

The embossing section included an engraved cylinder, an associated rubber cylinder, and an adhesive dispenser. The engraved cylinder was engraved with a microstructural pattern uniting a variety of embossed points. The glue dispenser contained a bath, an applicator, and an immersion cylinder.

The rewinding section included a perforating unit, a cutting unit, a winding unit, and an extraction unit. The perforating module included a perforating roller and a stationary support shaft. The cutting module included a cutting roller and a stationary support shaft.

In addition, the rewinding section was equipped with a spraying system consisting of four spray guns of the WA520 type (from Walther Pilot) with a nozzle diameter of 1.5 mm and operating at a pressure of 1.5, 2.0 or 2.5 bar (0.15 , 0.2 or 0.25 MPa), baths and pipelines supplying the coating composition from the bath to the atomizers.

Sprayers were positioned between the cutter and winder so that the cover composition was sprayed onto the underside of the continuous web of absorbent material upstream of the cut line at the start of the log, thereby defining the first end of the web (i.e., near-axial turns of the log / roll. hollow opening).

The log cutting section included numerous log cutting saws.

The various rollers are properly positioned to control the trajectory of the base absorbent log sheet along the paper machine, within and between the different sections. The base absorbent log webs are moved in the paper converting machine according to the machine direction (MD) from the unwinding units, towards the embossing unit, to the rewinding unit and to the log cutting unit.

The control module was connected to the winding module, to the perforating module, to the cutting module and to the spray guns via an interface. The control module controlled the operation of the perforation module, the cutter module and the proper deposition of the coating composition on the second end, and also controlled the winding force applied to the continuous web of absorbent material in the rewinding section.

The machine speed was maintained at 100 m / min throughout the tests.

Control Example 1 (control toilet paper with a density of 93 mg / cm ³ )

To obtain the desired tubeless toilet paper roll, a three-layer continuous web of absorbent material (basis weight: 55.6 g / m ² , thickness: 0.62 mm) as described above was pulled from the embossing section and fed to the rewinding section.

In the rewinding section, the continuous web first entered a perforating module, which pinched the web to form perforation lines oriented across the MD and regularly spaced apart from each other in the transverse direction (CD). The size of the perforated segment was 4 mm and the size of the non-perforated segment was 1 mm. The distance between the two perforation lines was 125 mm.

After pinching, the web of absorbent material entered a winding unit, in which the web was picked up by a temporary sleeve (outer diameter: 38 mm) using Tissue Tak 604 as the "fly glue". A continuous web (approximate total continuous web length: 17,500 mm; corresponding to 140 perforated sheets) was then wound onto a core to form a log having a diameter of 120 mm.

The resulting log was separated from the web of absorbent material in a cutting module, which cut the web across the MD. The resulting log was kept at a temperature of 20-22 ° C, 50% relative humidity for a period of 12 hours.

After incubation, the temporary sleeve was removed from the log in the extraction module. The resulting log was cut parallel to the MD with multiple saws to cut the log into multiple individual rolls having a width of 99 mm.

The density of the roll was 93 mg / cm ³ .

Control Example 2 (control toilet paper with a density of 119 mg / cm ³ )

A coreless roll was obtained in the same manner as described above in Test Example 1, except that a three-layer continuous web of absorbent material having an approximate total length of 22500 mm (corresponding to 180 perforated sheets) was wound onto a core to form a log having a diameter of 120 mm. ...

After aging, the temporary sleeve was removed from the log in an extraction module and the log was cut parallel to the MD with multiple saws to cut the log into multiple individual rolls having a width of 99 mm.

The density of the roll was 119 mg / cm ³ .

Control Example 3 (control toilet paper with a density of 149 mg / cm ³ )

A coreless roll was prepared in the same manner as described in Test Example 1 above, except that a three-layer continuous web of absorbent material having an approximate total length of 28125 mm (corresponding to 225 perforated sheets) was wound onto a core to form a log having a diameter of 120 mm. ...

After aging, the temporary sleeve was removed from the log in an extraction module and the log was cut parallel to the MD with multiple saws to cut the log into multiple individual rolls having a width of 99 mm.

The density of the roll was 149 mg / cm ³ .

Example 1 (toilet paper with HPMC and a density of 93 mg / cm ³ )

A coating composition was prepared by dissolving hydroxypropyl methylcellulose (HPMC) in water at a concentration of 3.7% by weight. The resulting coating composition was fed into spray guns and applied at room temperature (22 ° C).

To obtain the desired roll of toilet paper, a coreless roll was obtained in the same manner as described above in Test Example 1, except that after pinching / cutting and before winding the web, the coating composition was applied (sprayed) using spray guns (pressure: 2.5 bar (0.25 MPa)) to a length of about 3500 mm (that is, about 20% of the total length of the blade) upstream of the cut line.

The amount of HPMC applied to the continuous web was 0.148 g / roll (solids content of the HPMC applied to one individual roll, that is, after cutting the log).

The density of the roll was 93 mg / cm ³ .

Examples 2, 3, 4 and 5 (toilet papers with HPMC and density 93 mg / cm ³ )

Additional coreless toilet paper rolls were prepared in the same manner as described above in Example 1, except that the length of application, the pressure upon application and the amount of dry polymer applied to the continuous web in Examples 2, 3, 4 and 5 were as follows: as shown in Table 1 below.

The density of the rolls obtained in Examples 2, 3, 4 and 5 was 93 mg / cm ³ .

Examples 6 and 7 (toilet papers with HPMC and a density of 119 mg / cm ³ )

Sleeveless rolls of toilet paper were produced in the same manner as described above in Test Example 2, except that after pinching / cutting and before winding the web onto the continuous web using spray guns, a coating composition was applied (sprayed) as used in Example 1 above. (3.7 wt% HPMC in water).

The length of application, the pressure upon application, and the amount of dry polymer applied to the continuous web in Examples 6 and 7 were as shown in Table 1 below. The density of the rolls obtained was 119 mg / cm ³ .

Comparative Examples 1 and 2 (toilet papers with HPMC and weights of 93 mg / cm ³ and 119 mg / cm ³ )

Sleeveless rolls of toilet paper were prepared in the same manner as described above in Test Examples 1 or 2, except that after pinching / cutting and before winding the web onto continuous webs using spray guns, a coating composition was applied (sprayed) as used in Example 1 above (3.7 wt% HPMC in water).

Application length (Comparative Example 1: 1750 mm / 10% of the web length; Comparative Example 2: 3500 mm / 16% of the web length), the application pressure and the amount of dry polymer applied to the continuous web in Comparative Examples 1 and 2 were as follows: as shown in Table 1 below.

The density of the obtained rolls was 93 mg / cm ³ and 119 mg / cm ³ , respectively.

Comparative Examples 3 and 4 (toilet papers with HPMC and a density of 149 mg / cm ³ )

Sleeveless rolls of toilet paper were made in the same manner as described above in Test Example 3, except that after pinching / cutting and before winding the web onto the continuous web using spray guns, a coating composition was applied (sprayed) as used in Example 1 above. (3.7 wt% HPMC in water).

The application length, application pressure and the amount of dry polymer applied to the continuous web in Comparative Examples 1 and 2 were as shown in Table 1 below. The density of the rolls obtained was 149 mg / cm ³ .

The properties of the resulting rolls of toilet paper were evaluated according to the procedures described above. The results are shown in Table 1 below.

Table 1

Roll density (mg / cm ³ ) 93 (total length: 17500 mm) 119 (total length: 22500 mm) 149 (total length: 28125mm) Test Case 1 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Test Case 2 Example 6 Example 7 Comparative Example 2 Test Case 3 Comparative Example 3 Comparative Example 4 Application length (mm) - 3500 7000 8750 13125 16800 1750 - 9000 16875 3500 - 11250 14063 (%) - twenty 40 50 75 96 10 - 40 75 sixteen - 40 50 Application pressure (bar) - 2.5 2.0 2.0 2.5 2.5 2.0 - 2.0 2.0 1.5 - 2.0 2.0 Cover composition amount (g / roll) 0 0.148 0.178 0.189 0.400 0.381 0.041 0 0.167 0.366 0.070 0 0.122 0.215 Stiffness (N / mm) Axial K _ax 190 240 267 365 357 300 232 249 333 321 - 478 504 444 Radial K _rad 0.41 0.54 0.62 - 0.78 0.79 - 0.72 1.16 1.33 0.89 1.30 1.46 1.58 Elasticity (%) 66 82 86 91 92 95 72 70 93 91 72 79 77 78 Interleaf adhesion (N) 0.23 - 0.54 0.77 0.43 0.39 0.37 0.24 0.60 0.76 0.50 0.28 0.80 0.47 Perforation breaks and / or damage to sheets No - No No No No No No No No No No No No Flattening Yes No No No No No No Yes No No No Yes No No

These test data show that, according to the present invention, applying a particular coating composition to the second end of the continuous web and at least 20% of the total length of the continuous web, when combined with the proper coreless roll density, results in excellent resilience and several other benefits. The inner windings of the resulting coreless rolls exhibit very good flattening resistance. At the same time, the inter-sheet adhesion (peel force) in the roll is maintained within an acceptable range. In addition, the coreless rolls can be easily squeezed, which is difficult if the roll density is much more than 140 mg / cm ³ . This compressibility, combined with the resilience of the roll, results in an excellent product that can be stored in a compressed state, but again takes on, to a very high degree, its original shape and appearance if the compressive forces are removed.

In addition, the corresponding coated continuous web materials obtained in the examples of the invention were found to be degradable in the above test.

In addition, the rolls of the present invention can be unwound to the last sheet without tearing and / or damaging the sheets (i.e., without causing perforation to break and / or damage to the sheets when measuring the peel force).

Claims (39)

1. A coreless roll of absorbent sheet product formed by a spirally wound continuous web of absorbent material having a first end and a second end, the web of absorbent material being wound so as to create an axial hollow opening located in the center of the coreless roll and extending from one edge to the other the edges of the sleeveless roll, and in such a way that the first end is located on the outside of the roll, and the second end is located at the axial hollow opening: wherein the spirally wound continuous web of absorbent material has a density of 50 to 140 mg / cm ³ ; moreover, at least the last turn at the second end of the continuous web of absorbent material includes a cover composition containing a polymer comprising oxygen and / or nitrogen atoms, the turn being one turn of a continuous web spirally wound around an axial hollow opening; wherein at least 20% of the total length of the continuous web of absorbent material in the machine direction comprises a cover composition comprising a non-ionic polymer comprising oxygen and / or nitrogen atoms, and the total amount of non-ionic polymer is 0.001 to 40 g / roll. 2. The linerless roll of claim 1, wherein the coating composition is applied to only one side of the continuous web of absorbent material, preferably the side facing the axial hollow opening. 3. A sleeveless roll according to claim 1 or 2, wherein the polymer comprising oxygen and / or nitrogen atoms contained in the coating composition that is applied to the last coil (s) located at the second end is a non-ionic polymer, and preferably said coating composition is the same as a composition applied over at least 20% of the entire length of a continuous web of absorbent material. 4. Sleeveless roll according to any one of paragraphs. 1-3, in which the maximum inter-sheet adhesion between the coated portions of the continuous web of absorbent material and the portions of the continuous web in contact with them is 0.3 to 1.7 N. 5. Sleeveless roll according to any one of paragraphs. 1-4, wherein the coating composition that is applied to the continuous web of absorbent material has an ionic requirement of -1000 to +100 μeq / g, preferably -500 to +50 μeq / g, more preferably -50 to 0 μeq / G. 6. Sleeveless roll according to any one of paragraphs. 1-5, in which the non-ionic polymer includes at least one repeating structural unit containing one or more oxygen atoms and / or one or more nitrogen atoms. 7. The linerless roll of claim 6, wherein the nonionic polymer comprises at least one repeating structural unit containing one or more ether oxygen atoms and / or one or more hydroxyl groups. 8. The linerless roll according to claim 6 or 7, in which on average at least 50%, preferably at least 80%, of all repeating structural units constituting the non-ionic polymer include one or many oxygen atoms and / or one or more nitrogen atoms, preferably ether oxygen atoms and / or one or more hydroxyl groups. 9. Sleeveless roll according to any one of paragraphs. 1-8, in which the non-ionic polymer is a non-ionic cellulose ether. 10. The linerless roll of claim 9, wherein the nonionic cellulose ether has a number average molecular weight of 1,000 to 1,000,000, preferably 2,000 to 500,000, more preferably 3,000 to 200,000, more preferably 5,000 to 100,000. 11. The linerless roll of claim 9 or 10, wherein the nonionic cellulose ether is an alkyl cellulose ether such as methyl cellulose or ethyl cellulose, a hydroxyalkyl cellulose ether such as hydroxyethyl cellulose or hydroxypropyl cellulose, or a combination thereof. 12. Sleeveless roll according to any one of paragraphs. 1-8, in which the non-ionic polymer is a hydroxyl-terminated polyether, preferably a hydroxyl-terminated polyether selected from polyethylene glycol, polypropylene glycol, and mixtures thereof, more preferably polyethylene glycol, preferably at least 40% more preferably at least 50%, more preferably at least 70%, of the total length of the continuous web of absorbent material in the machine direction include a coating composition containing a coating composition containing a polyester polyol. 13. The coreless roll of claim 12, wherein the nonionic polymer has a number average molecular weight of 800 to 250,000, preferably 1,000 to 50,000, more preferably 1,500 to 15,000, more preferably 1,500 to 10,000, more preferably 2,000 to 7,500, for example , from 2500 to 4000. 14. Sleeveless roll according to any one of paragraphs. 1-13, wherein the coating composition comprises: (a) at least 50 wt.%, preferably at least 65 wt.%, more preferably at least 80 wt.% non-ionic polymer; (b) not more than 50 wt.%, preferably not more than 35 wt.%, more preferably not more than 20 wt.% additional additives such as plasticizers, strengthening agents, flavors and colorants; in each case based on the total solids content of the coating composition. 15. Sleeveless roll according to any one of paragraphs. 1-14, in which the coating composition is applied in molten form, or, after adding water, in the form of an aqueous solution, the aqueous solution preferably containing the non-ionic polymer in an amount of at least 0.1 wt.%, More preferably at least at least 0.5 wt.%, based on the total weight of the coating composition. 16. Sleeveless roll according to any one of paragraphs. 1-15, in which at least the last two, preferably at least the last three turns, preferably at least the last five turns, more preferably at least the last ten turns at the second end of the continuous absorbent web material include a coating composition. 17. Sleeveless roll according to any one of paragraphs. 1-16, wherein the coating composition is applied such that with respect to the length or lengths of the continuous web that includes the coating composition, the area covered by the coating composition is at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90% of the total area of the specified length (s) of the segment (- kov). 18. Sleeveless roll according to any one of paragraphs. 1-17, in which, if the coating composition has been applied continuously in the machine direction, the formed coated area begins at the second end and includes at least the last turn of the second end. 19. Sleeveless roll according to any one of paragraphs. 1-17, in which, if the coating composition has been applied intermittently in the machine direction, thereby creating two or more coated areas, (i) one coated area includes at least the last turn of the second end, and (ii) the amount of non-ionic polymer , applied to the half of the continuous web, including the second end, is preferably equal to or greater than the amount of non-ionic polymer applied to the half of the continuous web, including the first end. 20. Sleeveless roll according to any one of paragraphs. 1-19, in which the web of absorbent material is constituted by 1 tissue paper layer or 2 to 6, in particular 2 to 5, superposed tissue layers. 21. Sleeveless roll according to any one of paragraphs. 1-20 in compressed form. 22. Sleeveless roll according to any one of paragraphs. 1-21, which is an absorbent article selected from the group consisting of sanitary napkins, towels such as household towels, kitchen or hand towels, toilet papers, wiping papers, handkerchiefs, and facial wipes, wherein this absorbent article is preferably toilet paper. 23. A method for manufacturing a coreless roll of an absorbent sheet product, comprising: - moving a continuous web of absorbent material having a first end and a second end, which is preferably composed of 1 layer of tissue paper or from 2 to 6 superimposed layers of tissue paper; - optionally cutting the continuous web of absorbent material substantially cross-machine direction to obtain single but interlocked sheets; - application of a coating composition containing a non-ionic polymer as defined in any one of paragraphs. 1-19, on a continuous web; - spiral winding of a continuous web of absorbent material in such a way as to form a log of the web of absorbent material, while the web of absorbent material is wound in such a way as to form an axial hollow opening, positioned in the center with respect to the log and extending from one edge of the log to the other edge of the log, and so in such a way that the first end is on the outside of the log, and the second end is at the axial hollow opening; and - cutting the log into many caseless rolls. 24. A method of manufacturing according to claim 23, further comprising - subjecting a tubeless roll to compression in a direction perpendicular to the axial hollow opening to obtain a tubeless roll in a compressed form. 25. The method of manufacture according to claim 23 or 24, in which the linerless roll obtained by this method is as defined in any one of claims. 1-21. 26. The use of a sleeveless roll according to any one of paragraphs. 1-22 as toilet paper, household towel, hand towel, kitchen towel, wiping paper, facial tissue, handkerchief, or sanitary napkin.

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