WO2010032951A2

WO2010032951A2 - Method of manufacturing nonwoven web perforated without physical or thermal deformation and absorbent article having such nonwoven web

Info

Publication number: WO2010032951A2
Application number: PCT/KR2009/005255
Authority: WO
Inventors: Seong Seob Kim; Won Young Lee; Eo Yeon Hwang; Jea Seung Chin
Original assignee: Yuhan-Kimberly, Limited
Priority date: 2008-09-19
Filing date: 2009-09-16
Publication date: 2010-03-25
Also published as: JP5744156B2; BRPI0913723A2; CN102159757B; JP2014051771A; CN102159757A; BRPI0913723B8; JP2012503107A; BRPI0913723B1; KR20100033209A; RU2011115104A; JP2014062352A; ZA201102314B; AR073614A1; WO2010032951A3; MX2011002725A; RU2509182C2; JP5520304B2

Abstract

The present invention provides a method of manufacturing a nonwoven web perforated without physical or thermal deformation and an absorbent article including such a nonwoven web. The absorbent article of the present invention comprises the following: a liquid-permeable top sheet; a liquid-impermeable back sheet; an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body. The surge layer includes a nonwoven web perforated without physical or thermal deformation.

Description

METHOD OF MANUFACTURING NONWOVEN WEB PERFORATED WITHOUT PHYSICAL OR THERMAL DEFORMATION AND ABSORBENT ARTICLE HAVING SUCH NONWOVEN WEB

The present invention relates to a method of manufacturing a nonwoven web perforated without physical or thermal deformation and an absorbent article having such a nonwoven web. More particularly, the present invention relates to an absorbent article such as a diaper, a sanitary napkin for women, a liner, etc., which has a nonwoven web perforated without physical or thermal deformation while allowing a great amount of liquid discharged from a user's body to be rapidly captured and be easily delivered to an absorbent body.

One example of a conventional absorbent article is illustrated in FIG. 1. Referring to FIG. 1, a conventional absorbent article 10 includes: a liquid-permeable top sheet 2 of a body side; a liquid-impermeable back sheet 4 of an external side; an absorbent body 6 disposed between the top sheet 2 and the back sheet 4; and a surge layer 8 disposed between the top sheet 2 and the absorbent body 6.

The top sheet 2 may contact a user's skin. The top sheet 2 serves to provide softness such that the user feels comfortable while wearing the article. The absorbent body 6 serves to rapidly absorb the liquid discharged from the user's body through the top sheet 2 to contain the liquid therewithin. The absorbent body 6 may be fabricated from pulp fibers or pulp fibers mixed with ultra-absorptive particles. The back sheet 4 is disposed underneath the absorbent body 6. The back sheet 4 may be made from a liquid-impermeable film material such that the liquid retained within the absorbent body 6 is not discharged externally.

The surge layer 8 serves to rapidly absorb the liquid and deliver the absorbed liquid to the absorbent body to thereby prevent the user's skin from becoming wet. To this end, the surge layer 8 may be comprised of a nonwoven web having a low fiber density and a high bulkiness. However, fabricating such a surge layer needs materials of a high basis weight, which leads to high manufacturing costs. The surge layer 8 may be comprised of a perforated nonwoven web in order to sustain or enhance its performance while reducing its manufacturing costs.

According to the prior art, the surge layer is comprised of a perforated nonwoven web. Such a nonwoven web may be manufactured by physically cutting off a portion of a sheet of bonded fibers through means of a cutting device (e.g., punch) or perforating a sheet of bonded fibers by means of a heated pin. By way of another example, such a nonwoven web may have perforations as passing between one roll with protrusions thereon and the other roll configured to correspond thereto. Thus, a perforated nonwoven web may be deformed due to a physical or thermal pressure applied during a perforating process. Accordingly, there is a problem in that a density of the nonwoven web as well as a fiber density around the perforation increases (however, bulkiness decreases). Also, there is a further problem in that the physical or thermal pressure applied during a perforating process causes damage of fibers and stiffness of a surge layer.

The present invention is directed to solving the foregoing problems. The present invention provides a method of manufacturing a nonwoven web, which perforates the nonwoven web without applying a physical or thermal pressure to the nonwoven web, thereby preventing an increase of a fiber density of the nonwoven web and reducing damage of fibers while enhancing softness of a surge layer. The present invention also seeks to provide an absorbent article having such a nonwoven web.

A nonwoven web perforated without physical or thermal deformation according to one embodiment of the present invention may be manufactured by the following steps: blending fibers; opening the blended fibers; carding the opened fibers; perforating the carded fibers without physical or thermal deformation; bonding the perforated fibers; and finishing the bonded fibers.

Preferably, perforating may comprise intermittently ejecting air toward the carded fibers with a predetermined pressure to form a perforation and to push out the carded fibers around the perforation.

Preferably, perforating may be performed simultaneously along with carding. In such a case, the opened fibers may be carded on a conveyor with protrusions thereon to form a perforated web. Also, bonding may comprise applying a predetermined air pressure or a pressure caused by variable contact to a top side and/or a bottom side of the web.

In another aspect of the present invention, an absorbent article according to one embodiment may comprise the following: a liquid-permeable top sheet; a liquid-impermeable back sheet; an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body. The surge layer may include a nonwoven web perforated without physical or thermal deformation.

An absorbent article according to another embodiment of the present invention may comprise the following: a liquid-permeable top sheet; a liquid-impermeable back sheet; an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body. The top sheet may include the nonwoven web perforated without physical or thermal deformation.

An absorbent article according to yet another embodiment of the present invention may comprise the following: a liquid-permeable top sheet; a liquid-impermeable back sheet; an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body. The surge layer may include a laminate that includes a nonwoven web perforated without physical or thermal deformation and an imperforate nonwoven web laminated on a top and/or bottom side thereof.

In one embodiment, preferably, a total area of perforations may be in a range of 5~80% of an entire area of the nonwoven web. Preferably, a diameter of the perforation may be in a range of 2~30mm. More preferably, the diameter of the perforation may be in a range of 5~10mm. Preferably, a basis weight of the perforated nonwoven web may be in a range of 20~400gsm.

According to the method of manufacturing a nonwoven web of the present invention, perforations can be formed in the nonwoven web without physical or thermal deformation, thereby preventing increase of a fiber density around the perforation and reducing stiffness caused by the increase. Accordingly, a user can feel softness when such a nonwoven web is applied to the user's skin.

Further, since the nonwoven web can be fabricated with a low density and an increased void volume, the nonwoven web can rapidly deliver the liquid discharged from the user's body to the absorbent body.

Also, the nonwoven web may be fabricated to have the same thickness as an imperforate nonwoven web even when using a small amount of fibers. That is, the nonwoven web may be fabricated to have the same thickness as an imperforate nonwoven web despite using a material of low basis weight, which leads to the reduction of manufacturing costs.

When the perforation is sufficiently large sized, the top sheet can dent in part into the perforations, thereby reducing a contact area between the top sheet and the user's skin. Also, a distance between the top sheet and the absorbent body shortens via the perforation. As such, the absorbent body can absorb moisture contained within the top sheet by a capillary phenomenon. Thus, reduction of the contact area between the top sheet and the user's skin, as well as decrease of the moisture contained within the top sheet, allow the top sheet of the absorbent article to be maintained free of moisture.

If a ratio of the perforations to the nonwoven web is high, then the perforated nonwoven web may be weakened in intensity and is prone to deformation during the perforating process. In this respect, the perforated nonwoven web, which may be provided together with an imperforate nonwoven web, may be laminated on a top or bottom side of the perforated nonwoven web, thereby maintaining the high ratio of the perforations to the nonwoven web without decreasing the intensity of the nonwoven web.

FIG. 1 is a sectional view illustrating one example of a conventional absorbent article.

FIG. 2 is a perspective view illustrating one example of an absorbent article according to one embodiment of present invention.

FIG. 3 is a sectional view taken along the line Ⅲ-Ⅲ of FIG. 2.

FIG. 4 is a perspective view illustrating a nonwoven web for use in an absorbent article according to one embodiment of the present invention.

FIG. 5 schematically illustrates a perforating process after a carding process.

FIG. 6 is an enlarged view of a portion denoted by "A" of FIG. 5.

FIG. 7 schematically illustrates that opened fibers are carded as perforations are made therethrough.

FIG. 8 is a sectional view taken along the line Ⅷ-Ⅷ of FIG. 7.

Descriptions will be made in detail regarding a method of manufacturing a nonwoven web perforated without physical or thermal deformation and an absorbent article having such a nonwoven web according to embodiments of the present invention.

FIG. 2 is a perspective view illustrating one example of an absorbent article according to one embodiment of present invention. FIG. 3 is a sectional view taken along the line Ⅲ-Ⅲ of FIG. 2. FIG. 4 is a perspective view of a nonwoven web for use in an absorbent article according to one embodiment of the present invention

Referring to FIGS. 2 and 3, an absorbent article 100, which is constructed in accordance with one embodiment of the present invention, includes the following: a top sheet 110 to pass liquid or excrement discharged from a user's body therethrough; an absorbent body 130 containing the liquid from the top sheet 110 therewithin; a back sheet 120 disposed underneath the absorbent body 130 for preventing the liquid contained within the absorbent body 130 from leaking externally; and a surge layer 115 disposed between the top sheet 110 and the absorbent body 130 for rapidly delivering the liquid permeating through the top sheet 110 to the absorbent body 130. As shown in FIG. 2, when the absorbent article 100 is used for a diaper, the absorbent article 100 may further include an elastic member 150 for wrapping around a baby's legs and a waist band 160 for engaging a baby's waist.

The top sheet 110 (which may be referred to as "a liner" in the art) directly contacts the user's skin. The top sheet 110 allows the liquid discharged from the user's body to pass therethrough and then rapidly move to the absorbent body 130. Thus, it is advantageous for the top sheet 110 to have wettability, hydrophilicity and porosity. Preferably, the top sheet 110 may be made from a nonwoven web material, which has a relatively low density and is bulky in size. The nonwoven web materials may comprise one type of fiber such as polyester or polypropylene, a bicomponent or conjugate fiber having a component of low melting point and a component of high melting point. For example, the fibers may include nylon, polyester, cotton, acrylic fiber, etc. or combinations thereof. The bicomponent fiber may consist of a polyester core and a polyethylene sheath.

The absorbent body 130 is disposed between the top sheet 110 and the back sheet 140 for rapidly absorbing and retaining the liquid therewithin. In general, the absorbent body 130 must be compressive, compliable and non-stimulating to the user's skin. For example, the absorbent body 130 may be made from pulp fibers or pulp fibers mixed with ultra-absorptive particles.

The back sheet 140 is disposed beneath the absorbent body 130. The back sheet 140 may be made from a liquid-impermeable polyethylene film such that the liquid captured within the absorbent body 130 is discharged externally to spot or stain the user's undergarments.

The surge layer 115 is disposed between the top sheet 110 and the absorbent body 130. The surge layer 115 serves to rapidly absorb the liquid permeating through the top sheet 110 and deliver the absorbed liquid to the absorbent body 130 to prevent the absorbed liquid from permeating toward the user' skin. The surge layer 115 may be a bonded carded web or an air laid web made from natural and/or synthetic fibers. The bonded carded web may be, for example, a powder bonded carded web, an infrared bonded carded web or a through air bonded carded web (TABCW).

To increase an absorption rate of the surge layer 115 and enhance its softness, a nonwoven web 120 perforated without physical or thermal deformation according to one embodiment of the present invention may be used as the surge layer 115.

In another embodiment, the nonwoven web 120 perforated without physical or thermal deformation according to one embodiment of the present invention may also be used as the top sheet 110.

In another embodiment, the nonwoven web 120 perforated without physical or thermal deformation according to one embodiment of the present invention may be used as the surge layer 115 in the form of a laminate wherein an imperforate nonwoven web is laminated on the nonwoven web 120. In such a case, the imperforate nonwoven web may be disposed between the top sheet 110 and the perforated nonwoven web 120 or between the perforated nonwoven web 120 and the absorbent body 130. The imperforate nonwoven web may include, but is not limited to, a spun-bond web, a bonded carded web, an airlaid web, a through air bonded carded web, etc. Preferably, a basis weight of the imperforate nonwoven web may be in a range of 10~30gsm.

The top sheet 110, the nonwoven web 120, the absorbent body 130 and the back sheet 140 may be assembled into various well-known forms of absorbent articles using conventional techniques known in the art. For example, the above-described components can be joined to one another by using a thermal or ultrasonic bonding, hot melted adhesives and combinations thereof or any other suitable attaching means.

FIG. 4 is a perspective view illustrating the nonwoven web perforated without physical or thermal deformation according to one embodiment of the present invention. As shown in FIG. 4, a plurality of perforations is formed or defined in a sheet 121 of the nonwoven web 120. In one embodiment, the nonwoven web 120 may be manufactured by the following steps: blending fibers; opening the blended fibers; carding the opened fibers; perforating the carded fibers without physical or thermal deformation; bonding the perforated fibers; and finishing the bonded fibers.

The steps such as bending, opening, carding, bonding and finishing may be performed according to conventional techniques known in the art.

Preferably, a total area of perforations may be in a range of 5~80% of an entire area of the nonwoven web. Preferably, a diameter of a perforation may be in a range of 2~30mm. More preferably, particularly in terms of an absorption time, the diameter of a perforation may be in a range of 5~10mm. Preferably, a basis weight of the perforated nonwoven web may be in a range of 20~400gsm.

FIG. 5 schematically illustrates the perforating process after the carding process. FIG. 6 is an enlarged view of a portion denoted by "A" of FIG. 5.

Referring to FIGS. 5 and 6, in one embodiment, the nonwoven web 120 may be perforated by blowing or ejecting air toward the carded fibers under a predetermined pressure after the carding process. Blowing or ejecting air may be performed in an intermittent manner or continuously for a predetermined time period. In one embodiment for perforating the carded fibers 121a, air tubes 170 may be positioned or arranged perpendicularly to a plane of a sheet 121 of the carded fibers 121a. If air is ejected or blown from the air tube toward the sheet 121 of the carded fibers, then a section thereof, against which the ejected air impinges, is pushed out or blown out to form or define a perforation or aperture 122a. By doing so, before the bonding process, the perforation or aperture 122a is formed in the sheet 121 of the carded fibers 121a. Thereafter, if the bonding process is performed, then the perforation 122 is formed or defined in the nonwoven web as shown in FIG. 4.

In another embodiment, the perforating process and the carding process may be simultaneously performed so as to form the perforated nonwoven web, as illustrated in FIGS. 7 and 8. FIG. 7 schematically illustrates that opened fibers are carded as perforations or apertures are formed therethrough. FIG. 8 is a sectional view taken along the line Ⅷ-Ⅷ of FIG. 7. As shown in FIGS. 7 and 8, the perforated nonwoven web may be fabricated in such a manner that the opened fibers are carded on a carding conveyor 180 with protrusions or pins 181 thereon. The protrusions or pins may have a round or polygonal cross-section or a tapered shape. As can be clearly seen from FIG. 8, as the opened fibers are carded on the carding conveyor 180, perforations such as the perforation 122a shown in FIG. 6 are formed in the sheet of the carded fibers 121b by the protrusions 181 perforating therethrough. After such carding process is completed, a bonding process may be performed in such a manner that a predetermined air pressure or a variable contact pressure is applied to a top side and/or a bottom side of a sheet of the carded fibers 121b. Through such bonding process, the perforations 122, which correspond to the protrusions 181 of the carding conveyor 180 in shape and size, may be formed in the nonwoven web 120, as shown in FIG. 4.

According to the above-described perforating processes, there is no loss of the fibers during the manufacture of the nonwoven web 120. Also, there is no deformation caused by the physical or thermal pressure.

The above-described embodiments for the perforating process are provided for illustrative purposes only and are not intended to limit the present invention to specific process as described therein. The nonwoven web may be perforated by various other methods that do not cause deformation due to the physical or thermal pressure.

Table 1 provided below shows the thickness values and density values in imperforate nonwoven webs and nonwoven web perforated by ejecting air according to one embodiment of the present invention.

Table 1

	Code C	Code G	Code F
Thickness(mm)	1.87	1.69	1.86
Density(g/cm³)	0.043	0.041	0.037

Code C: Nonwoven web of TABCW material (80gsm, no perforation)

Code G: Nonwoven web of TABCW material (70gsm, no perforation)

Code F: Nonwoven web of TABCW material (70gsm, perforated by ejecting air)

As shown in Table 1, if a basis weight of the nonwoven web is reduced under the same condition (e.g., comparison between Code C and Code G), then the density decreases and the thickness becomes thin. However, the perforated nonwoven web (Code F) according to the present invention has a thickness almost equal to that of Code C and a density still lower than that of Code C despite using materials of a basis weight smaller than that of Code C. Further, the perforated nonwoven web (Code F) according to the present invention has a thickness thicker than that of Code G and a density still lower than that of Code G despite using materials of the same basis weight as Code G. Consequently, the perforated nonwoven web (Code F) according to the present invention can thicken and lower its density despite using materials of a basis weight smaller than those of Codes C and G, thereby reducing the use amount of raw materials.

Table 2 provided below shows experimental results on the liquid-absorption rate and the amount of evaporating moisture (g/s/m²) of absorbent articles including a surge layer of a nonwoven web, wherein only the surge layer is different and any components other than the surge layer are the same.

Table 2

	Code C	Code F
First absorption time(sec)	19.08	17.08
Second absorption time(sec)	24.92	20.60
Third absorption time(sec)	26.72	23.42
Amount of evaporating moisture(g/s/m²)	21.87	18.59

Code C: Absorbent article including a surge layer of TABCW material (80gsm, no perforation)

Code F: Absorbent article including a surge layer of TABCW material (70gsm, perforated by ejecting air)

As shown in Table 2, the absorption time of the absorbent article including the perforated nonwoven web (Code F) decreases by about 10 to about 17% over the absorbent article of Code C. Further, the amount of evaporating moisture of the absorbent article including the perforated nonwoven web (Code F) increases by about 15% over the absorbent article of Code C. Thus, the absorbent article according to the present invention can rapidly absorb the liquid discharged from the user's body therewithin and further have a significant amount of evaporating moisture per second, thereby being free of moisture for a long time.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various alternations or modifications may be made without departing from the scope of the present invention.

Claims

A method of manufacturing a nonwoven web perforated without a physical or thermal deformation, comprising:

blending fibers;

opening the blended fibers;

carding the opened fibers;

perforating the carded fibers without the physical or thermal deformation;

bonding the perforated fibers; and

finishing the bonded fibers.
The method of Claim 1, wherein perforating comprises intermittently ejecting an air toward the carded fibers with a predetermined pressure to form a perforation and to push out the carded fibers around the perforation.
The method of Claim 1, wherein carding and perforating are simultaneously performed in such a manner that the opened fibers are carded on a conveyor with protrusions thereon to form a perforated web, and

wherein bonding comprises applying a predetermined air pressure or a variable pressure to a top side and/or a bottom side of the web.
A nonwoven web perforated without a physical or thermal deformation, which is manufactured by a method according to any one of Claims 1 to 3.
The nonwoven web of Claim 4, wherein a total area of perforations is in a range of 5~80% of an entire area of the nonwoven web.
The nonwoven web of Claim 4, wherein a diameter of the perforation is in a range of 2~30mm.
The nonwoven web of Claim 6, wherein the diameter of the perforation is in a range of 5~10mm.
The nonwoven web of Claim 4, wherein a basis weight of the perforated nonwoven web is in a range of 20~400gsm.
An absorbent article, comprising:

a liquid-permeable top sheet;

a liquid-impermeable back sheet;

an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and

a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body, the surge layer including a nonwoven web perforated without a physical or thermal deformation according to Claim 4.
The absorbent article of Claim 9, wherein a total area of perforations is in a range of 5~80% of an entire area of the nonwoven web.
The absorbent article of Claim 9, wherein a diameter of the perforation is in a range of 2~30mm.
The absorbent article of Claim 11, wherein the diameter of the perforation is in a range of 5~10mm.
The absorbent article of Claim 9, wherein a basis weight of the perforated nonwoven web is in a range of 20~400gsm.
An absorbent article, comprising:

a liquid-permeable top sheet;

a liquid-impermeable back sheet;

an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and

a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body, the surge layer including a laminate that includes a nonwoven web perforated without a physical or thermal deformation according to Claim 4 and an imperforate nonwoven web laminated thereon.
The absorbent article of Claim 14, wherein a total area of perforations is in a range of 5~80% of an entire area of the nonwoven web.
The absorbent article of Claim 14, wherein a diameter of the perforation is in a range of 2~30mm.
The absorbent article of Claim 16, wherein the diameter of the perforation is in a range of 5~10mm.
The absorbent article of Claim 14, wherein a basis weight of the perforated nonwoven web is in a range of 20~400gsm.
The absorbent article of Claim 14, wherein a basis weight of the imperforate nonwoven web is in a range of 10~30gsm.
An absorbent articles, comprising:

a liquid-permeable top sheet;

a liquid-impermeable back sheet;

an absorbent body disposed between the top sheet and the back sheet for absorbing a liquid permeating through the top sheet; and

a surge layer disposed between the top sheet and the absorbent body for delivering the liquid permeating through the top sheet to the absorbent body,

wherein the top sheet includes a nonwoven web perforated without a physical or thermal deformation according to Claim 4.
The absorbent article of Claim 20, wherein a total area of perforations is in a range of 5~80% of an entire area of the nonwoven web.
The absorbent article of Claim 20, wherein a diameter of the perforation is in a range of 2~30mm.
The absorbent article of Claim 22, wherein the diameter of the perforation is in a range of 5~10mm.
The absorbent article of Claim 20, wherein a basis weight of the perforated nonwoven web is in a range of 20~400gsm.