METHOD OF FORMING FIBROUS PADS
United States Patent 3851356
An air-laid fibrous web is confined between a lower foraminous support member and an upper pad engaging surface having a shape of a fibrous pad to be formed. A pressure differential is established across the foraminous support member for removing unconfined portions of the fibrous web to thereby form a fibrous pad underlying the pad-engaging surface and having substantially the same shape as the pad-engaging surface.
US Patent References:
Machine for making sanitary pads
Teall - June 1938 - 2121454
Method for making a cellulosic product
Bletzinger et al. - March 1960 - 2926394
Manufacture of sanitary product
Champaigne, Jr. - January 1968 - 3366115
METHOD OF MAKING SANITARY NAPKINS AND THE LIKE
Franz - May 1969 - 3445897
MACHINE FOR MAKING SANITARY NAPKINS
Banks - July 1970 - 3518726
Machine for making sanitary pads
Teall - June 1938 - 2121454
Method for making a cellulosic product
Bletzinger et al. - March 1960 - 2926394
Manufacture of sanitary product
Champaigne, Jr. - January 1968 - 3366115
METHOD OF MAKING SANITARY NAPKINS AND THE LIKE
Franz - May 1969 - 3445897
MACHINE FOR MAKING SANITARY NAPKINS
Banks - July 1970 - 3518726
Application Number:
05/337932
Publication Date:
12/03/1974
Filing Date:
03/05/1973
View Patent Images:
Export Citation:
Assignee:
Scott Paper Company (Delaware County, PA)
Primary Class:
International Classes:
A61F13/15; A61L15/00
Field of Search:
19/144,145,145.5,148,144.5 425/80-82 83/53 264/93,145,154,160,DIG.70 156/62.2,62.4,62.6
US Patent References:
| 3527858 | METHOD FOR FINISHING FULL-FASHIONED BRASSIERE BLANKS | September 1970 | Braxton et al. |
Primary Examiner:
Newton, Dorsey
Attorney, Agent or Firm:
Faigus, Martin Foley William L. J.
Claims:
What is claimed is
1. A method for forming at least one discrete fibrous pad having a predetermined shape from an air-laid fibrous web, said method comprising the steps of:
2. The method according to claim 1, including the step of confining said web between said support member and a plurality of spaced discrete surfaces to leave web sections between said discrete surfaces unconfined, and subjecting the unconfined web sections between the spaced discrete surfaces to a stream of gas for removing said unconfined sections from the web to form a plurality of spaced, discrete fibrous pads having substantially the same shape as the discrete surfaces.
3. The method according to claim 1, wherein said support member is foraminous, and said stream of gas is created by establishing a pressure differential through said support member.
4. The method according to claim 3, wherein said pressure differential is established by directing a gas under positive pressure through said support member from below said support member and establishing a partial vacuum from above said support member.
1. A method for forming at least one discrete fibrous pad having a predetermined shape from an air-laid fibrous web, said method comprising the steps of:
2. The method according to claim 1, including the step of confining said web between said support member and a plurality of spaced discrete surfaces to leave web sections between said discrete surfaces unconfined, and subjecting the unconfined web sections between the spaced discrete surfaces to a stream of gas for removing said unconfined sections from the web to form a plurality of spaced, discrete fibrous pads having substantially the same shape as the discrete surfaces.
3. The method according to claim 1, wherein said support member is foraminous, and said stream of gas is created by establishing a pressure differential through said support member.
4. The method according to claim 3, wherein said pressure differential is established by directing a gas under positive pressure through said support member from below said support member and establishing a partial vacuum from above said support member.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to method and apparatus for forming absorbent fibrous pads, and specifically to method and apparatus for forming absorbent fibrous pads suitable for use as an absorbent component in disposable products, such as disposable diapers, sanitary napkins and the like.
2. Description of the Prior Art
Disposable sanitary products, such as disposable diapers, sanitary napkins and the like, normally include an absorbent fibrous pad disposed between a backing sheet and a fluid-pervious facing sheet. Such pads can be shaped to have a central crotch region of less width than a forward and rearward region thereof. In addition, such pads can be profiled to have a greater basis weight in one predetermined region thereof than in other predetermined regions.
U.S. Pat. Application Ser. No. 237,963, assigned to Scott Paper Company, discloses a method and apparatus for forming shaped and/or profiled fibrous pads. According to the teachings of the above application, the pads are formed by directing a gaseous suspension of substantially individualized fibers toward a formation assembly which includes three-dimensional pad-receiving pad to be formed. A partial vacuum is pulled through a foraminous bottom wall of each compartment to direct the gas of said suspension through the bottom walls and deposit the fibers in the three-dimensional compartments to form fibrous pads having substantially the same shape as said compartments. The pads formed in such three-dimensional compartments are sometimes difficult to remove, especially, if such compartments have sharp corners. The fibrous pads tend to cling to the side surfaces of the three-dimensional compartments in the sharp corner regions, and cannot be easily removed from said compartments without damaging the formed pad. Also, high basis weight pads, (e.g., over 65 oz. per yd. 2 ), cannot easily be formed in such three-dimensional compartments. To further explain, at commercial speeds and forming distances a high pressure drop must be established through the compartments to deposit such a high basis weight of fibers therein. This high pressure drop excessively densifies the fiber layer within the compartments before the requisite weight of fibers is deposited therein to render further formation difficult, if not impossible.
U.S. Pat. No. 3,661,680, assigned to Riegel Textile Corporation, discloses an apparatus for forming disposable diapers in which a continuous fibrous web is separated into discrete web sections by removing narrow transverse bands of fibers from the continuous web. The apparatus includes an outer, rotating shell having a transverse slot therein. A stationary vacuum chamber having a slot therein is mounted within the outer shell. As the slot in the outer shell rotates into alignment with the slot of the vacuum chamber, the vacuum applied through the vacuum chamber will be effective to remove a narrow transverse band of fibers from the continuous web. This apparatus is acceptable for removing narrow transverse sections from a continuous web; however, practical machine design considerations impose dimensional limitations on the size of the outer shell which renders this means of removing fibrous web sections somewhat limited. For example, it would be extremely difficult, if not impossible, to utilize the approach disclosed in the U.S. Pat. No. 3,661,680 to form discrete fibrous webs which are spaced a relatively large distance apart. To accomplish this objective, the outer shell would have to be exceptionally large to provide a large slot area overlying a large area of the fibrous web for removing large sections of said web. Practical space limitations might prevent the use of such a large outer shell.
SUMMARY OF THE INVENTION
Method and apparatus of this invention for forming at least one discrete fibrous pad from an air-laid fibrous web employ at least one pad-forming shoe having a pad-engaging surface with the same predetermined shape as a fibrous pad to be formed. The fibrous web is confined between a support member and the pad-engaging surfaces of the pad-forming shoes, and unconfined portions of the fibrous web are removed to form fibrous pads underlying the pad-engaging surfaces and having substantially the same shape as said pad engaging surfaces.
According to a preferred embodiment of this invention, the lower support member is foraminous, and the fibers are removed by establishing a pressure differential across the support member. Preferably, the pressure differential is established by directing air under positive pressure through the foraminous support member from the lower surface thereof, and establishing a partial vacuum from above the upper surface of the fibrous web. Preferably, the fibers which are removed from the support member are directed into the web forming device in which is formed the air-laid fibrous web from which the discrete fibrous pads are formed.
The air-laid fibrous web can be formed by any conventional web forming device, such as the Rando-Webber manufactured by Curlator Corporation of Rochester, New York. In addition, a multiplicity of fibrous webs can be formed in separate devices, and these webs can be superimposed upon each other to provide extremely large basis weight fibrous webs from which extremely large basis weight discrete fibrous pads can be formed. If desired, the fibrous web can be formed with a profile, i.e., different basis weights in different regions, to permit the formation of profiled fibrous pads. For example, a fibrous web can be formed with a profile according to the method and apparatus disclosed in Lee et al. U.S. Pat. No. 3,641,627, issued Feb. 15, 1972.
The present invention permits formation of extremely large basis weight fibrous pads by forming the pads from superimposed air-laid fibrous webs manufactured by multiple air-laying devices. In addition, the method and apparatus of this invention permits the formation of discrete fibrous pads without utilizing three-dimensional pad formation compartments and thereby eliminates the problem of pad removal which is encountered by forming pads in such compartments.
Other objects and advantages of this invention will become apparent upon reading the detailed description which follows, taken in conjunction with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic, side elevation view of a preferred apparatus of this invention; and
FIG. 2 is a schematic, isometric view showing various stages of formation of a discrete, fibrous pad from an air-laid fibrous web.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Referring to FIG. 1, the pad forming apparatus 10 of this invention forms discrete fibrous pads 12 from an air-laid fibrous web 14 manufactured in any suitable web-forming device, such as the Rando-Webber, manufactured by Curlator Corporation of Rochester, N.Y.
The pad-forming apparatus 10 includes a plurality of pad-forming shoes 16 mounted on an endless conveyor 18, and the endless conveyor 18 is positively driven in the direction indicated by arrow 20 by any conventional drive means (not shown). Each pad-forming shoe 16 has a pad-engaging surface 17 of substantially the same shape as a fibrous pad to be formed. The fibrous web 14 is directed into the pad forming apparatus 10 on a foraminous support member 22, which, in the preferred embodiment of this invention is the foraminous forming surface upon which the air-laid fibrous web 14 is formed.
The continuous fibrous web 14 in conveyed on the foraminous support member 22 through a pad-forming region in which air under positive pressure is directed through the support member from a manifold 26 which is positioned below said support member. In addition, the pad-forming region includes a vacuum chamber 28 positioned above said support member, and the vacuum chamber is connected to a suitable vacuum source, such as a fan 29.
Referring to FIGS. 1 and 2, the fibrous web 14 is confined between the foraminous support member 22 and the pad-engaging surfaces 17 as said web is directed through the pad-forming region. A pressure differential is established through the foraminous support member 22 by directing air under positive pressure through the manifold 26, and by establishing a partial vacuum in vacuum chamber 28 through operation of fan 29. This pressure differential effects removal of the sections of the fibrous web 14 which are unconfined, to thereby form discrete fibrous pads 12 underlying the pad-engaging surfaces 17.
The foraminous support member 22 includes a section 23 which diverges from the pad-engaging surfaces 17 of the pad-forming shoes 16 at the downstream end of the pad-forming region to effect separation of the pad-engaging surfaces 17 from the formed fibrous pads 12. A partial vacuum is applied from below the foraminous support member 22 in this diverging section 23 through a vacuum box 32 to establish allegience of the formed pad 12 for the foraminous support member 22. The discrete fibrous pads 12 can then be directed to converting equipment (not shown) to permit use of said pads in the formation of sanitary products, such as disposable diapers, sanitary napkins and the like.
Preferably, the fibers which are removed through vacuum source 28 in the pad-forming region 25 are directed back into the fiberizing device to be utilized in the forming of the fibrous web 14.
Several modifications can be made within the scope of this invention. The pad-forming shoes 16 can be secured, or manufactured integral with, a cylindrical conveyor, as opposed to fastening the pad-forming shoes to the endless conveyor 18. The foraminous support member 22 can be replaced with an air-impervious support member. If the support member is impervious, the unconfined fibrous web regions can be removed by directing air under pressure across the upper surface of the support member, since a partial vacuum cannot be established through said support member. The number of pad-forming shoes 16 which are in engagement with the fibrous web 14 within the pad-forming region at any instant of time is, within practical limits, a matter of design choice. For example, the equipment can be designed so that only one pad-forming shoe 16 cooperates with the support member 22 to confine the fibrous web, at any instant of time, within the pad-forming region 25. The specific shape of the pad-engaging surfaces 17 is a matter of design choice, and is dictated by the specific shape of the fibrous pads to be formed. The fibrous web 14 can be formed as a continuous fibrous web or as discrete, separate web sections.
1. Field of the Invention
This invention relates generally to method and apparatus for forming absorbent fibrous pads, and specifically to method and apparatus for forming absorbent fibrous pads suitable for use as an absorbent component in disposable products, such as disposable diapers, sanitary napkins and the like.
2. Description of the Prior Art
Disposable sanitary products, such as disposable diapers, sanitary napkins and the like, normally include an absorbent fibrous pad disposed between a backing sheet and a fluid-pervious facing sheet. Such pads can be shaped to have a central crotch region of less width than a forward and rearward region thereof. In addition, such pads can be profiled to have a greater basis weight in one predetermined region thereof than in other predetermined regions.
U.S. Pat. Application Ser. No. 237,963, assigned to Scott Paper Company, discloses a method and apparatus for forming shaped and/or profiled fibrous pads. According to the teachings of the above application, the pads are formed by directing a gaseous suspension of substantially individualized fibers toward a formation assembly which includes three-dimensional pad-receiving pad to be formed. A partial vacuum is pulled through a foraminous bottom wall of each compartment to direct the gas of said suspension through the bottom walls and deposit the fibers in the three-dimensional compartments to form fibrous pads having substantially the same shape as said compartments. The pads formed in such three-dimensional compartments are sometimes difficult to remove, especially, if such compartments have sharp corners. The fibrous pads tend to cling to the side surfaces of the three-dimensional compartments in the sharp corner regions, and cannot be easily removed from said compartments without damaging the formed pad. Also, high basis weight pads, (e.g., over 65 oz. per yd. 2 ), cannot easily be formed in such three-dimensional compartments. To further explain, at commercial speeds and forming distances a high pressure drop must be established through the compartments to deposit such a high basis weight of fibers therein. This high pressure drop excessively densifies the fiber layer within the compartments before the requisite weight of fibers is deposited therein to render further formation difficult, if not impossible.
U.S. Pat. No. 3,661,680, assigned to Riegel Textile Corporation, discloses an apparatus for forming disposable diapers in which a continuous fibrous web is separated into discrete web sections by removing narrow transverse bands of fibers from the continuous web. The apparatus includes an outer, rotating shell having a transverse slot therein. A stationary vacuum chamber having a slot therein is mounted within the outer shell. As the slot in the outer shell rotates into alignment with the slot of the vacuum chamber, the vacuum applied through the vacuum chamber will be effective to remove a narrow transverse band of fibers from the continuous web. This apparatus is acceptable for removing narrow transverse sections from a continuous web; however, practical machine design considerations impose dimensional limitations on the size of the outer shell which renders this means of removing fibrous web sections somewhat limited. For example, it would be extremely difficult, if not impossible, to utilize the approach disclosed in the U.S. Pat. No. 3,661,680 to form discrete fibrous webs which are spaced a relatively large distance apart. To accomplish this objective, the outer shell would have to be exceptionally large to provide a large slot area overlying a large area of the fibrous web for removing large sections of said web. Practical space limitations might prevent the use of such a large outer shell.
SUMMARY OF THE INVENTION
Method and apparatus of this invention for forming at least one discrete fibrous pad from an air-laid fibrous web employ at least one pad-forming shoe having a pad-engaging surface with the same predetermined shape as a fibrous pad to be formed. The fibrous web is confined between a support member and the pad-engaging surfaces of the pad-forming shoes, and unconfined portions of the fibrous web are removed to form fibrous pads underlying the pad-engaging surfaces and having substantially the same shape as said pad engaging surfaces.
According to a preferred embodiment of this invention, the lower support member is foraminous, and the fibers are removed by establishing a pressure differential across the support member. Preferably, the pressure differential is established by directing air under positive pressure through the foraminous support member from the lower surface thereof, and establishing a partial vacuum from above the upper surface of the fibrous web. Preferably, the fibers which are removed from the support member are directed into the web forming device in which is formed the air-laid fibrous web from which the discrete fibrous pads are formed.
The air-laid fibrous web can be formed by any conventional web forming device, such as the Rando-Webber manufactured by Curlator Corporation of Rochester, New York. In addition, a multiplicity of fibrous webs can be formed in separate devices, and these webs can be superimposed upon each other to provide extremely large basis weight fibrous webs from which extremely large basis weight discrete fibrous pads can be formed. If desired, the fibrous web can be formed with a profile, i.e., different basis weights in different regions, to permit the formation of profiled fibrous pads. For example, a fibrous web can be formed with a profile according to the method and apparatus disclosed in Lee et al. U.S. Pat. No. 3,641,627, issued Feb. 15, 1972.
The present invention permits formation of extremely large basis weight fibrous pads by forming the pads from superimposed air-laid fibrous webs manufactured by multiple air-laying devices. In addition, the method and apparatus of this invention permits the formation of discrete fibrous pads without utilizing three-dimensional pad formation compartments and thereby eliminates the problem of pad removal which is encountered by forming pads in such compartments.
Other objects and advantages of this invention will become apparent upon reading the detailed description which follows, taken in conjunction with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic, side elevation view of a preferred apparatus of this invention; and
FIG. 2 is a schematic, isometric view showing various stages of formation of a discrete, fibrous pad from an air-laid fibrous web.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Referring to FIG. 1, the pad forming apparatus 10 of this invention forms discrete fibrous pads 12 from an air-laid fibrous web 14 manufactured in any suitable web-forming device, such as the Rando-Webber, manufactured by Curlator Corporation of Rochester, N.Y.
The pad-forming apparatus 10 includes a plurality of pad-forming shoes 16 mounted on an endless conveyor 18, and the endless conveyor 18 is positively driven in the direction indicated by arrow 20 by any conventional drive means (not shown). Each pad-forming shoe 16 has a pad-engaging surface 17 of substantially the same shape as a fibrous pad to be formed. The fibrous web 14 is directed into the pad forming apparatus 10 on a foraminous support member 22, which, in the preferred embodiment of this invention is the foraminous forming surface upon which the air-laid fibrous web 14 is formed.
The continuous fibrous web 14 in conveyed on the foraminous support member 22 through a pad-forming region in which air under positive pressure is directed through the support member from a manifold 26 which is positioned below said support member. In addition, the pad-forming region includes a vacuum chamber 28 positioned above said support member, and the vacuum chamber is connected to a suitable vacuum source, such as a fan 29.
Referring to FIGS. 1 and 2, the fibrous web 14 is confined between the foraminous support member 22 and the pad-engaging surfaces 17 as said web is directed through the pad-forming region. A pressure differential is established through the foraminous support member 22 by directing air under positive pressure through the manifold 26, and by establishing a partial vacuum in vacuum chamber 28 through operation of fan 29. This pressure differential effects removal of the sections of the fibrous web 14 which are unconfined, to thereby form discrete fibrous pads 12 underlying the pad-engaging surfaces 17.
The foraminous support member 22 includes a section 23 which diverges from the pad-engaging surfaces 17 of the pad-forming shoes 16 at the downstream end of the pad-forming region to effect separation of the pad-engaging surfaces 17 from the formed fibrous pads 12. A partial vacuum is applied from below the foraminous support member 22 in this diverging section 23 through a vacuum box 32 to establish allegience of the formed pad 12 for the foraminous support member 22. The discrete fibrous pads 12 can then be directed to converting equipment (not shown) to permit use of said pads in the formation of sanitary products, such as disposable diapers, sanitary napkins and the like.
Preferably, the fibers which are removed through vacuum source 28 in the pad-forming region 25 are directed back into the fiberizing device to be utilized in the forming of the fibrous web 14.
Several modifications can be made within the scope of this invention. The pad-forming shoes 16 can be secured, or manufactured integral with, a cylindrical conveyor, as opposed to fastening the pad-forming shoes to the endless conveyor 18. The foraminous support member 22 can be replaced with an air-impervious support member. If the support member is impervious, the unconfined fibrous web regions can be removed by directing air under pressure across the upper surface of the support member, since a partial vacuum cannot be established through said support member. The number of pad-forming shoes 16 which are in engagement with the fibrous web 14 within the pad-forming region at any instant of time is, within practical limits, a matter of design choice. For example, the equipment can be designed so that only one pad-forming shoe 16 cooperates with the support member 22 to confine the fibrous web, at any instant of time, within the pad-forming region 25. The specific shape of the pad-engaging surfaces 17 is a matter of design choice, and is dictated by the specific shape of the fibrous pads to be formed. The fibrous web 14 can be formed as a continuous fibrous web or as discrete, separate web sections.