Patent Description:
The present invention also relates to a method for producing absorbent sanitary articles.

An absorbent sanitary article typically has a structure that comprises a rectangular-shaped central body or chassis having a front section and a rear section. The chassis is normally formed by a permeable topsheet intended to come into contact with the user's skin when the article is worn, an impermeable backsheet and an absorbent core sandwiched between the topsheet and the backsheet. The front and rear section of the chassis are normally closed around the user's waist by means of hook-and-loop fasteners, better known as Velcro© fastening devices.

In many cases the absorbent sanitary article has a front panel of micro-loop material attached to the front section of the chassis and one pair of elastic back side panels which extend laterally from opposite sides of the rear section of the chassis. The elastic back side panels are provided with fastening tabs, typically comprising micro-hooks pads, which can be releasably attached to the front panel of micro-loop material for closing the absorbent sanitary article around the waist of the user.

The front panel of a hook-and-loop fastener is formed of a fibrous material, for example polypropylene, provided on an upper surface with micro-loops suitable for engaging with the micro-hooks of the side panels. The loop-material is normally fixed to a support typically consisting of a film of plastic material or of a non-woven polypropylene or the like.

<CIT> describes a multi-layer material for diaper front panels, comprising a support formed of a polyolefinic film and a layer of loop-material formed by a non-woven polyolefinic material. The support and the layer of loop-material are normally secured together by glue.

In conventional solutions, loop material attached to the support is supplied in reels, which are cut transversely to form the front panels which are applied to the outer surface of respective backsheet in the respective front sections. The front panels are normally connected to the backsheet by glue or by ultrasonic welding. Welding is generally not suitable because it can compromise the impermeability of the backsheet.

The backsheet of a diaper is normally a multi-layer composite structure including an inner impermeable film and an outer layer made of a non-woven web connected to the impermeable film by a layer of glue. The front panel is applied on the outer surface of the non-woven web of the backsheet, usually by a layer of glue.

The production of prior art elastic back side panels requires micro-hook pads produced starting from continuous tapes, usually made of relatively rigid thermoplastic material, having continuous or intermittent micro-hook formations integrally formed thereon. The continuous tape with integrally formed micro-hook formations is cut to form a plurality of discrete micro-hook pads. Such discrete micro-hook pads are spaced by a desired pitch and are fixed in spaced positions on a surface of a continuous non-woven support web. The continuous non-woven support web with the micro-hook pads fixed thereon is then cut to form fastening tabs each including a non-woven support web of soft material and a micro-hook pad of relatively rigid thermoplastic material fixed on a surface of the non-woven support web by glue or by welding.

The continuous tapes of micro-hook and micro-loop material are manufactured by suppliers specialized in manufacturing hook-and-loop fasteners. The micro-hook ad micro-loop tapes are packaged in reels which are delivered to the manufacturing plants of absorbent sanitary articles. In the machines for manufacturing absorbent sanitary articles the reels of continuous tapes with integrally formed micro-hook and micro loop formations are unwound, cut, spaced, and fixed to the continuous non-woven support web. All these operations require complex and expensive dedicated equipment which increase the complexity of the machines for manufacturing absorbent sanitary articles. Since the cost of the micro-hook tapes is high, the dimension of the micro-hook pads is kept to the minimum possible, which requires complex equipment for cutting the continuous micro-hook tapes in very small pieces and for feeding such small pieces with high precision to the continuous non-woven support web.

A further drawback of the prior art is that the micro-hook fastening pads of relatively rigid plastic material are positioned on the inner surfaces of the back side panels, which face the skin of the user when the diaper is applied to the user. This may give rise to an unpleasant stiffness and sharpness perception during the application of the sanitary article to the wearer. Also, the user may get scratches or abrasions due to the contact with sharp and rigid micro-hook pads.

<CIT> discloses an apparatus and process for forming micro-hooks on a substrate for use as hook-type fasteners in touch fastening systems, wherein vibration energy is used to soften a substrate which is positioned between a mold and a source of vibration. The mold includes a plurality of cavities into which the softened substrate is forced to form the projections. The substrate may comprise a film, sheet, web, composite, laminate, etc. The source of vibration may be an ultrasonic horn. The process to form such micro-hooks may be operated in a continuous, semi-continuous or intermittent manner.

<CIT>, <CIT> and <CIT> disclose absorbent articles with hook-and-loop fastening means.

The object of the present invention is to provide an absorbent sanitary article which overcomes the problems of the prior art.

According to the invention, this object is achieved by an absorbent sanitary article having the features of claim <NUM>.

According to another aspect, the invention relates to a method for manufacturing absorbent sanitary articles having the features of claim <NUM>.

The claims form an integral part of the technical disclosure provided here in relation to the invention.

The present invention will now be described with reference to the attached drawings, provided purely by way of non-limiting example, wherein:.

It should be appreciated that the attached drawings are schematic and not to scale with respect to real products. Various figures may not be represented in the same scale. Also, in various figures some elements may not be shown to better show other elements.

With reference to <FIG>, numeral <NUM> indicates an absorbent sanitary article according to the present invention. <FIG> shows the absorbent sanitary article <NUM> in the configuration in which it is worn. <FIG> show various embodiments of absorbent sanitary articles <NUM> according to the present invention in a flat configuration.

The absorbent sanitary article <NUM> comprises a chassis <NUM> elongated along a longitudinal axis X. The chassis <NUM> has two side edges <NUM> parallel to the longitudinal axis X, a front section <NUM> and a rear section <NUM>. The front section <NUM> and the rear section <NUM> in use are closed around the user's waist. Between the front section <NUM> and the rear section <NUM> a groin section <NUM> extends which, in use, is arranged between the legs of the user.

The chassis <NUM> comprises a topsheet <NUM> made of a permeable material which, in use, is in contact with the user's skin, an impermeable backsheet <NUM> and an absorbent core <NUM> sandwiched between the topsheet <NUM> and the backsheet <NUM>. The chassis <NUM> may comprise additional components as usual in the field of absorbent sanitary articles, such as elastic leg cuffs, acquisition and diffusion layers, etc..

The absorbent sanitary article <NUM> comprises a hook-and-loop fastening device <NUM> configured for fastening the front section <NUM> and the rear section <NUM> to each other.

The hook-and-loop fastening device <NUM> comprise a micro-hook front panel <NUM> located in the front section <NUM> of the chassis <NUM>. The micro-hook front panel <NUM> includes a plurality of micro-hooks <NUM> integrally formed on a portion of the outer surface of the backsheet <NUM>, which are formed as it will be disclosed in the following.

The hook-and-loop fastening device <NUM> comprise two back side panels <NUM> attached to the rear section <NUM> of the chassis <NUM> and extending laterally beyond respective side edges <NUM> in a transverse direction Y orthogonal to the longitudinal axis X. The side panels <NUM> have respective micro-loop areas <NUM> configured for forming a releasable surface connection with the micro-hook front panel <NUM>. The micro-loop areas <NUM> may be formed by a portion of a non-woven web. The side panels <NUM> may be elastically stretchable the transverse direction Y.

The absorbent sanitary article <NUM> may comprises a pair of front side panels <NUM> projecting laterally from opposite sides of the front section <NUM>, having the function of facilitating attachment of the back side panels <NUM> to the micro-hook front panel <NUM> when the absorbent sanitary article <NUM> is closed around the user's waist.

The backsheet <NUM> with the integral micro-hook front panel <NUM> may be produced by a method disclosed in <CIT> and schematically shown in <FIG>.

With reference to <FIG>, a continuous non-woven web <NUM> moving in its longitudinal direction A passes through a micro-hook forming unit <NUM>. The micro-hook forming unit <NUM> comprises a moulding roller <NUM> rotating about an axis B transversal to the longitudinal direction A of the continuous non-woven web <NUM>. The moulding roller <NUM> has a plurality of micro-cavities open on its outer cylindrical surface <NUM>. The micro-hook forming unit <NUM> comprises an ultrasonic horn <NUM> which compresses the continuous non-woven web <NUM> against the outer cylindrical surface <NUM> of the moulding roller <NUM> as the continuous non-woven web <NUM> moves in the direction A.

The vibrating energy produced by the ultrasonic horn <NUM> liquifies or fluidifies locally the non-woven material of the continuous non-woven web <NUM>, which penetrates in a fluid or liquid state in the micro-cavities of the moulding roller <NUM>. The material of the non-woven web <NUM> which penetrates in the cavities of the molding roller <NUM> cools in contact with the walls of the micro-cavities and forms micro-hook front panels <NUM> integral with the continuous non-woven web <NUM>.

As shown in <FIG>, at the exit of the micro-hook forming unit <NUM> the continuous non-woven web <NUM> has an array of micro-hook front panels <NUM> spaced apart from each other in the longitudinal direction A.

The array of spaced apart micro-hook front panels <NUM> may be obtained by providing on the outer surface <NUM> of the moulding roller <NUM> an intermittent pattern of micro-cavities. Alternatively, the moulding roller <NUM> may have a continuous pattern of micro-cavities and the array of spaced apart micro-hook front panels <NUM> may be formed by intermittently turning off the ultrasonic horn <NUM>. As a further alternative, the moulding roller <NUM> may have a continuous pattern of micro-cavities and the array of spaced apart micro-hook front panels <NUM> may be formed by intermittently detaching the ultrasonic horn <NUM> from the outer cylindrical surface <NUM> of the moulding roller <NUM>.

At the exit of the micro-hook forming unit <NUM> the continuous non-woven web <NUM> with the array of spaced apart integrally formed micro-hook front panels <NUM> is overlapped and fixed to a continuous impermeable film <NUM> moving in the same direction A as the continuous non-woven web <NUM>. With reference to <FIG> and <FIG>, the continuous non-woven web <NUM> and the continuous impermeable film <NUM> may be fixed to each other by a layer of glue <NUM> which may be applied on a surface of the continuous impermeable film <NUM> by a glue dispenser <NUM>.

The continuous non-woven web <NUM> and the continuous impermeable film <NUM> form a continuous backsheet comprising an inner impermeable film <NUM> and an outer non-woven layer <NUM> fixed to the inner impermeable film <NUM> e.g. by a layer of glue <NUM>, wherein an array of micro-hook front panels <NUM> is integrally formed on an outer surface of the outer non-woven layer <NUM>.

In order to form micro-hooks with dimensions sufficient for an effective hook-and-loop connection, the continuous non-woven layer <NUM> should have a weight of <NUM>-<NUM>/m<NUM>.

With reference to <FIG>, in a possible embodiment, an additional continuous web <NUM> may be applied on the continuous non-woven web <NUM> before passing the two webs <NUM>, <NUM> through the micro-hook forming unit <NUM>. The additional continuous web <NUM> may be a thermoplastic film or a non-woven web of a material different or identical to the material of the continuous non-woven web <NUM>. After passing through the micro-hook forming unit <NUM>, the additional continuous web <NUM> and the continuous non-woven web <NUM> form a unitary layer with integrally formed micro-hook front panels <NUM>. The use of an additional web <NUM> may allow a reduction of the weight of the continuous non-woven web <NUM>. For instance, in a possible embodiment two continuous non-woven webs <NUM>, <NUM> may be used, each having a weight of <NUM>/m2, which is a standard weight of non-woven webs in the field of absorbent sanitary articles.

In a possible embodiment, the micro-hook forming unit <NUM> may be a thermomechanical forming unit, in which the material of the non-woven web <NUM>, or webs <NUM>, <NUM>, is locally liquified or fluidified by heating and compression.

With reference to <FIG>, in a possible embodiment the micro-hooks <NUM> of the micro-hook front panel <NUM> may be arranged in a plurality of discrete pads <NUM>.

With reference to <FIG>, in a possible embodiment the micro-hooks <NUM> of the micro-hook front panel <NUM> may be arranged in a pattern <NUM> forming images, writings or numbers. The numbers may provide a visual indication of the position for attaching the back side panels <NUM>. Images and writings may indicate the trademark of the producer or the trade-name of the article.

With reference to <FIG>, the back side panel <NUM> comprises a first non-woven web <NUM>, a second non-woven web <NUM> and an elastic film <NUM> sandwiched between the first and second non-woven web <NUM>, <NUM>. The elastic film <NUM> is elastically stretchable in a transversal direction Y.

The first and second non-woven web <NUM>, <NUM> have respective pleated central portions <NUM>, <NUM>, respective non-pleated proximal portions <NUM>, <NUM> and respective non-pleated distal portions <NUM>, <NUM>. The first and second non-woven web <NUM>, <NUM> and the elastic film <NUM> are fixed to each other, e.g. by a pattern of spot welds <NUM>. The non-pleated proximal portions <NUM>, <NUM> are fixed to the chassis <NUM>. The surface of the non-pleated distal portion <NUM> forms a micro-loop area <NUM> which forms the loop portion of a hook-and-loop fastening connection.

The back side panels <NUM> have a soft feeling to the touch because they do not have micro-hooks. The back side panels <NUM> do not require the application of discrete micro-hook pads and this involves considerable advantages in that there is no need for complex and expensive devices for applying discrete elements at the distal portions of the side panels <NUM>.

The micro-hook front panel <NUM> is relatively soft as compared to the prior art micro-hook pads, because the micro-hooks <NUM> are obtained starting from non-woven material, which is softer than the thermoplastic material forming the traditional micro-hooks of hook-and-loop fastening devices. The micro-hook front panel <NUM> is located on an outer surface of the absorbent sanitary article, which does not contact the skin of the user when the absorbent sanitary article is applied to the user.

The hook-and-loop fastening device of the absorbent sanitary article according to the present invention is integrally formed on materials which are already present in the structure of the absorbent sanitary article. The hook-and-loop fastening device <NUM> of the absorbent sanitary article according to the present invention does not require reels of micro-hook ad micro-loop tapes to be transported and delivered to the manufacturing plants of absorbent sanitary articles. The invention has therefore considerable advantages regarding lower costs of materials, simpler manufacturing machines and an improved sustainability.

The absorbent sanitary articles <NUM> according to the present invention may be manufactured by a method comprising:.

The outer surface of the distal portion <NUM> of said first non-woven web <NUM> forms said micro-loop area <NUM>.

The chain of chassis <NUM> is then cut transversely to form individual absorbent sanitary articles <NUM>.

The formation of the micro-hook front panels <NUM> on the outer surface of the continuous backsheet <NUM> may comprise:.

Claim 1:
An absorbent sanitary article comprising:
- a chassis (<NUM>) having a longitudinal axis (X), two side edges (<NUM>), a front section (<NUM>) and a rear section (<NUM>), the chassis including a topsheet (<NUM>), a backsheet (<NUM>) having an outer surface, and an absorbent core (<NUM>) sandwiched between the topsheet (<NUM>) and the backsheet (<NUM>),
- a micro-hook front panel (<NUM>) including a plurality of micro-hooks (<NUM>) integrally formed on a portion of the outer surface of said backsheet (<NUM>) in said front section (<NUM>) of the chassis (<NUM>), and
- two back side panels (<NUM>) attached to said rear section (<NUM>) of the chassis (<NUM>) and extending laterally beyond respective side edges (<NUM>) in a transverse direction (Y) orthogonal to said longitudinal axis (X), the back side panels (<NUM>) having respective micro-loop areas (<NUM>) configured for forming a hook-and-loop connection with said micro-hook front panel (<NUM>), wherein said back side panels (<NUM>) are elastically stretchable in said transverse direction (Y), and wherein each of said back side panels comprises:
- a first and a second non-woven web (<NUM>, <NUM>), having respective pleated central portions (<NUM>, <NUM>) and respective non-pleated proximal and distal portions (<NUM>, <NUM>, <NUM>, <NUM>) on opposite sides of said pleated central portions (<NUM>, <NUM>), and
- an elastic film (<NUM>) sandwiched between said pleated central portions (<NUM>, <NUM>) of said first and a second non-woven web (<NUM>, <NUM>),
wherein the outer surface of the distal portion (<NUM>) of said first non-woven web (<NUM>) forms said micro-loop area (<NUM>).