WO2013068868A1

WO2013068868A1 - Apparatus and process for applying absorbent cores on a moving web

Info

Publication number: WO2013068868A1
Application number: PCT/IB2012/055882
Authority: WO
Inventors: Gabriele Sablone
Original assignee: Fameccanica.Data S.P.A.
Priority date: 2011-11-08
Filing date: 2012-10-25
Publication date: 2013-05-16
Also published as: ITTO20111027A1

Abstract

An apparatus for applying absorbent cores (96) on a moving supporting web (14), comprising: - first conveyors (16) configured for feeding a continuous supporting web (14) in a first direction (A) at a first speed (V1); - a forming section (54) configured for forming a continuous chain (82) comprising a first web (74) and a second web (76), and a continuous succession of absorbent pads (84) set at a first distance (D1) apart from one another, wherein the first and second webs (74, 76) are joined together along the perimeter of said absorbent pads (84); - second conveyors (86) configured for feeding said continuous chain (82) in a second direction (C) at a second speed (V2) lower than said first speed (V1); and - an application unit (56) configured for cutting said continuous chain (82) crosswise in spaces (94) between said adjacent and separate absorbent pads (84) and separating individual absorbent cores (96) from said continuous chain (82), said application unit (56) being moreover configured for accelerating said absorbent cores (96) from said second speed (V2) to said first speed (V1) and for applying the absorbent cores (96) on said continuous supporting web (14) moving at said first speed (VI) in positions set apart from one another by a second distance (D2) greater than said first distance (D1).

Description

"Apparatus and process for applying absorbent cores on a moving web"

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TEXT OF THE DESCRIPTION

Field of the invention

The present invention relates to the production of absorbent sanitary products and regards an apparatus and a process for applying absorbent cores that include cellulose fluff and superabsorbent polymers on a moving web.

Description of the relevant art

The document No. WO-A-2010049832 filed in the name of the present applicant describes a process for applying, in positions spaced apart, on an advancing web of material, lengths of a first material and a second material set on top of one another. The process described in this document envisages starting from two continuous webs of a first material and a second material. The two continuous webs are subjected to cutting separately so as to form lengths of the first material and of the second material. The cut lengths of the first material and of the second material are set on top of one another and then transferred onto an advancing supporting web material in positions spaced apart from one another.

Recently, there have been developed machines for the production of absorbent sanitary products operating at a very high speed, which are able to produce absorbent sanitary products with a rate of 1000 pieces/min and wherein the web on which the absorbent cores are applied advances at a speed of the order of 500 m/min.

With the solutions currently known there are problems in applying the absorbent cores on the moving web with a high precision of positioning and preventing any creases. Said difficulties become progressively more serious as the rate of advance of the web increases. Further difficulties are encountered in the case where the absorbent cores contain a large amount of superabsorbent polymers.

Object and summary of the invention

The object of the present invention is to provide an apparatus and a process for applying absorbent cores on a moving web that will enable the problems of the known art to be overcome. In particular, the object of the invention is to provide an apparatus and a process that will enable application of the absorbent cores on the supporting web with high precision and without the formation of creases, even with webs that advance at a high rate and with absorbent cores with a high amount of superabsorbent polymers. A further object of the invention is to provide an apparatus that will not require major interventions in the case of changes of format .

According to the present invention, the above objects are achieved by an apparatus and by a process having the characteristics that form the subject of Claims 1 and 8.

Brief description of the drawings

The present invention will now be described in detail with reference to the attached drawings, which are provided purely by way of non-limiting example and in which:

- Figure 1 is a schematic view of a line for the production of absorbent sanitary products;

- Figure 2 is a view at a larger scale of an apparatus for formation and application of absorbent cores indicated by the arrow II in Figure 1; and

- Figure 3 is a further enlarged view of the part indicated by the arrow III in Figure 2. Description of preferred embodiments

With reference to Figure 1, designated as a whole by 10 is a line for the production of absorbent sanitary products. The line 10 comprises an initial station 12 configured for feeding a continuous web 14 in a direction of advance A at a first speed VI .

For the purposes of the present invention, the web 14 could be made up in any way. It could be a single web or a composite web. The materials that form the web 14 may be of any type used in the sector of production of absorbent sanitary articles. In the example illustrated, the initial station 12 comprises one or more belt conveyors 16 that feed the web 14 in the rectilinear direction A at the speed VI and a series of unwinding assemblies 18, 20, 22, 24 that feed respective continuous webs, which, once joined to one another, form the continuous composite web 14. In the example illustrated, the first unwinding assembly 18 feeds a topsheet 26 formed, for example, by a continuous web of non-woven fabric, the second unwinding assembly 20 feeds an acquisition and diffusion layer (ADL) , which is applied on the top surface of the topsheet 26, the unwinding assembly 22 feeds webs 30 for the barriers around the user's legs, and the unwinding assembly 24 feeds elastic bands 32 for said leg barriers. In this example, the web 14 is hence formed by a topsheet 26, an acquisition and diffusion layer 28, and two leg barriers 30 with the corresponding elastic bands 32. The leg barriers 30 with the corresponding elastic bands are applied on the side of the topsheet 26 opposite to the side on which the acquisition and diffusion layer 28 is applied.

Set downstream of the initial station 12 is an apparatus 34 for formation and application of absorbent cores. The apparatus 34 will be described in greater detail hereinafter with reference to Figure 2. The apparatus 34 is configured for applying absorbent cores on the moving web 14 in positions set apart from one another in the direction of movement A.

Set downstream of the apparatus 14 is a station 36 that applies a backsheet 38 on the web 14 carrying the absorbent cores. The station 36 comprises an unwinding assembly 40 that feeds the backsheet 38 and possibly an unwinding assembly 42 that feeds a front web 44.

Set downstream of the station 36 are a unit 46 for application of closing tapes and a unit 48 that makes the cut of the openings for the user's legs. Moreover provided are a station 50 for longitudinal folding of the continuous composite web and a unit 52 for final transverse cutting, following upon which individual absorbent sanitary products separate from one another are obtained.

With reference to Figure 2 there now follows a description of the apparatus 34 that carries out formation and application of the absorbent cores on the web 14. The apparatus 34 comprises a section for formation of the cores 54 configured for forming a continuous chain of absorbent cores. The apparatus 34 further comprises an application unit 56 designed to separate individual absorbent cores from the continuous chain of absorbent cores and to apply the individual absorbent cores on the moving web 14 in positions set apart from one another in the direction of movement 14.

The forming section 54 comprises a forming wheel 58 that is able to turn in the direction indicated by the arrow B and a forming chamber 60 facing a part of the peripheral surface of the forming wheel 58. Contained in the forming chamber 50 is a mixture of cellulose fluff and superabsorbent polymers. The mixture of cellulose fluff and superabsorbent polymers is supplied to the chamber 60 via a channel 62. The cellulose fluff is supplied to the channel 62 by a mill 64, which produces the cellulose fluff starting from a continuous sheet of cellulose 66. The superabsorbent polymers are supplied to the channel 62 in the form of powders via an ejector 48.

The forming station 54 comprises two feed assemblies 70, 72 that feed a first continuous web 74 and a second continuous web 76, respectively, to the forming wheel 58 starting from respective reels. The permeable tissues 74, 76 can be constituted by non- woven fabric or by tissue paper. The first web 74 is supplied at the periphery of the forming wheel 58 upstream of the forming chamber 60. The second web 76 is supplied at the periphery of the forming wheel 58 downstream of the forming chamber 60. A first dispenser 78 applies a layer of glue on the first web 74, and a second dispenser 80 applies a layer of glue on the second web 76.

The forming wheel 58 is provided on its outer surface with holes connected to a source of negative pressure (not illustrated) .

The mixture of cellulose fluff and superabsorbent powder contained inside the forming chamber 60 is in contact with the first web 74 adherent to the peripheral surface of the forming wheel 58. The negative pressure, through the forming wheel 58, attracts a layer of cellulose fluff and superabsorbent powder towards the forming wheel 58. The surface facing the outside of the first web 74 is coated by a layer of glue. The suction through the forming wheel 58 forms a layer of cellulose fluff and superabsorbent powder on the outer surface of the first web 74. The layer of cellulose fluff and superabsorbent powder is withheld on the surface of the first web 74 by gluing. At the outlet of the forming chamber 60 the second web 76 is applied on the layer of cellulose fluff and superabsorbent powder applied on the first web 74. The glue applied on the top surface of the second web 76 connects the second web 76 to the layer of cellulose fluff and superabsorbent polymers carried by the first web 74.

On the outer surface of the forming wheel 58 there can be provided areas without suction holes so as to form at regular intervals areas of separation without the layer of cellulose fluff and superabsorbent powder.

Obtained downstream of the forming wheel 58 is a continuous chain 82 of absorbent cores, illustrated in greater detail in Figure 3. The continuous chain 82 is formed by a continuous succession of absorbent pads 84 of cellulose fluff and superabsorbent polymers sandwiched between the two webs 74, 76.

With reference to Figure 2, the continuous chain 82 is made to pass through a compression assembly 85 in which the two webs 74, 76 are compressed together. Following upon compression, the webs 74, 76 stick together in the areas in which the layer of cellulose fluff and superabsorbent powder is not present thanks to the layers of glue present on their mutually facing surfaces. With reference to Figure 3, the chain 82 is formed by a succession of absorbent pads 84 sandwiched between two continuous webs 74, 76. The webs 74, 76 have a width greater than the width of the absorbent pads 84 and are joined together around the absorbent pads 84. The absorbent pads 84 are set at a distance Dl apart from one another by areas 94 in which the two webs 74, 76 are joined together by gluing. Joining between the webs 74, 76 around the pads 84 could also be obtained in a way different from gluing, for example by heat-sealing. With reference to Figures 2 and 3, the continuous chain 82 is fed in a direction C at a speed V2 lower than the speed VI at which the web 14 advances in the direction A. In the example illustrated, the direction C is parallel and opposite to the direction A. The continuous chain 82 advances in the direction C on conveyors 86. A dispenser 88 applies a layer of glue on the continuous chain 82 whilst this advances in the direction C.

With reference to Figure 3, the application unit

56 comprises a transfer wheel 90 that is able to turn in the direction indicated by the arrow F. The application unit 56 comprises a cutting wheel 92 co^¬ operating with the transfer wheel 90 for cutting the continuous chain 82 at regular intervals. The cutting wheel 92 is synchronized with the movement of advance of the chain 82 in the direction C so as to cut in the transverse direction the continuous chain 82 in the spaces 94 between the absorbent pads 84. After cutting of the continuous chain 82 a plurality of individual absorbent cores 96 is formed made up of respective absorbent pads 84 of cellulose fluff and superabsorbent powder enclosed between two webs 74, 76 joined together around the pads 84.

The individual absorbent cores 96 are transferred by the transfer wheel 90 onto the web 14 moving in the direction A. The individual absorbent cores 96, after cutting, are withheld on the outer surface of the transfer wheel 90 by suction. The outer surface of the transfer wheel 90 is perforated, and situated within the transfer wheel 90 is a suction box 98 connected to a source of negative pressure. The suction box 98 is stationary and has a surface facing a sector of surface of the transfer wheel 90. In the stretch of the outer surface of the transfer wheel 90 facing the suction box 98, the individual absorbent cores 96 are withheld on the outer surface of the transfer wheel 90 by the negative pressure produced by the suction box 98.

The transfer wheel 90 turns in the direction indicated by the arrow F at a speed such that the peripheral speed of the transfer wheel 90 is equal to the speed VI of the web 14 in the direction A. The continuous chain 82 moves in the direction C at a speed V2 lower than the speed VI. Consequently, the transfer wheel 90 slides with respect to the chain 82. Immediately after the cut performed by the cutting wheel 92, the individual absorbent cores 96 accelerate from the speed V2 to the speed VI . As a result of the acceleration from the speed V2 to the speed VI, the individual absorbent cores 96 are set at a distance D2 apart from one another greater than the distance Dl between the pads 84 in the continuous chain 82. The individual absorbent cores 96 are applied to the web 14 set at the distance D2 from one another in the direction A. The cores 96 adhere to the web 14 since present on the surface of the absorbent cores 96 facing the web 14 is a layer of glue applied by the dispenser 88 on the continuous chain 82.

The fact that the absorbent pad 84 of cellulose fluff and superabsorbent polymers is enclosed between two webs 74, 76 enables handling of the individual absorbent cores 96 at a high rate and positioning of the absorbent cores 96 on the web 14 with high precision and without the formation of creases.

A particularly significant advantage of the solution according to the present invention is that the changes of format can be set via the program and without the need for replacement of parts.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what has been described and illustrated herein, without thereby departing from the scope of the invention as defined in the ensuing claims.

Claims

1. An apparatus for applying absorbent cores (96) on a moving supporting web (14), comprising:

- first conveyors (16) configured for feeding a continuous supporting web (14) in a first direction (A) at a first speed (VI);

- a forming section (54) configured for forming a continuous chain (82) comprising a first web (74) and a second web (76) and a continuous succession of absorbent pads (84) set at a first distance (Dl) apart from one another, wherein the first and second webs (74, 76) are joined together along the perimeter of said absorbent pads (84);

- second conveyors (86) configured for feeding said continuous chain (82) in a second direction (C) at a second speed (V2) lower than said first speed (VI); and

- an application unit (56) configured for cutting said continuous chain (82) crosswise in spaces (94) between said adjacent and separate absorbent pads (84) and separating individual absorbent cores (96) from said continuous chain (82), said application unit (56) being moreover configured for accelerating said absorbent cores (96) from said second speed (V2) to said first speed (VI) and for applying the absorbent cores (96) on said continuous supporting web (14) moving at said first speed (VI) in positions set apart from one another by a second distance (D2) greater than said first distance (Dl) .

2. The apparatus according to Claim 1, wherein said forming section (54) comprises a forming wheel (58) and a forming chamber (60) facing a sector of the outer surface of the forming wheel (58), the forming chamber (60) being configured for containing a mixture of cellulose fluff and superabsorbent polymers.

3. The apparatus according to Claim 2, wherein said forming section (54) comprises a first unwinding device (70) and a second unwinding device (72), which are configured for supplying the first and second continuous webs (74, 76) on the periphery of the forming wheel (58) upstream and downstream of the forming chamber (60), respectively.

4. The apparatus according to Claim 3, comprising a first dispenser (78) and a second dispenser (80) configured for applying respective layers of glue on the first web (74) and on the second web (76) .

5. The apparatus according to any one of the preceding claims, comprising a compression unit (84) configured for compressing said continuous chain (82) and joining together said first and second webs (74, 76) .

6. The apparatus according to Claim 1, wherein said application unit (56) comprises a transfer wheel (90) configured for rotating at a peripheral speed equal to said first speed (VI) .

7. The apparatus according to Claim 6, wherein said application unit (56) comprises a cutting device (92) co-operating with said transfer wheel (90) .

8. A process for applying absorbent cores (96) on a moving supporting web (14), comprising the steps of:

- feeding said supporting web (14) in a first direction (A) at a first speed (VI);

forming a continuous chain (82) comprising a first web (74) and a second web (76) and a continuous succession of absorbent pads (84) set at a first distance (Dl) apart from one another, wherein the first and second webs (74, 76) are joined together along the perimeter of said absorbent pads (84);

- feeding said continuous chain (82) in a second direction (C) at a second speed (V2) lower than said first speed (VI);

- cutting said continuous chain (82) crosswise in a space (94) between said adjacent absorbent pads (84) so as to separate individual absorbent cores (96);

- accelerating said absorbent cores (96) from said second speed (V2) to said first speed (VI); and

- applying said absorbent cores (96) on said supporting web (14) moving at said first speed (VI) in positions set at a second distance (D2) apart from one another greater than said distance (Dl) .

9. The process according to Claim 8, wherein said step of forming said continuous chain (82) comprises the steps of feeding said first and said second webs (74, 76) on the periphery of a forming wheel (58), respectively, upstream and downstream of a forming chamber (60) containing a mixture of cellulose fluff and superabsorbent polymers.