CA1195465A - Method and apparatus for debossing and selectively aperturing a resilient plastic web - Google Patents

Abstract

METHOD AND APPARATUS FOR DEBOSSING AND
SELECTIVELY APERTURING A RESILIENT PLASTIC WEB

Delmar John Bishop ABSTRACT
Method and apparatus for constructing a three-dimensional film forming structure for imparting a selectively apertured three-dimensional pattern to a heated plastic material which is either fed in film form from a supply roll or extruded as a melt directly onto the surface of said forming structure and subjected to a fluid pressure differential while in contact with its surface. In a preferred embodiment, the film forming structure comprises a stacked laminate of initially imperforate planar sheets having continuous patterns of apertures therein and at least one initially perforate selectively apertured planar sheet located beneath the uppermost continuously apertured sheet. The laminate forming structure is preferably tubular in shape so as to facilitate contin-uous plastic web processing against its outermost surface. Film to be debossed and selectively aper-tured is brought in contacting relation with the laminate structure and subjected to a fluid pressure differential on said forming structure while at a temperature above its softening temperature. The fluid pressure causes the heated plastic film to be debossed in those areas where said initially perforate selectively apertured lamina contacts the film and debossed and apertured in those areas where said initially perforate selectively apertured lamina does not contact the film. The debossed and selectively apertured film is thereafter cooled below its softening temperature before removal from the forming structure.

Description

METHOD AND APPARATUS FOR DEBOSSING AND
SELECTIVELY APERTURING A RESILIENT PLASTIC WEB

Delmar John Bishop TECHNICAL FIELD
,, The present invention has xelation tQ
select.ively aper~ured, resilien~ plastic webs exhibiting three-dimensional characteristics.
5The presen-t invention has further rela-tion to resilient plastic webs exhibiting a substantially uniform surface texture and appearance, but which are pervious to the passage of fluids only in dis-crete preselected areas oE the web or at preselected points along the entire surface of the web.
The present invention has further r~lation to method and apparatus fqr vacuwn forming said plastic webs by uniformly heating said webs across their entire surface and applying a uniform vacuum level opposite the film-contacting surface of a foxming structure of the present invention.
The present invention has still further xelation to methods for constructing ilm forming structures suitable for debossing and selectively 20 aperturing said plastic webs~

BACXGROUND ART
. . .
Selectively apertured sheets of material such as rubber, latex, plastic and the like have lons been known in the prior art. Typ.ic~1 prior art structuxes and processes for making them are disclosed in U~S. Patent ~,268,678 issued to Tingey on January 6, 1942; V.S. Patent 2,354,916 issued to Hurt on August l~ 1944, and Reissue Patent 23,910 issued to Smith et al. on December 14~ 1954O The patent to Tingey dis loses a process which comprises applying a latex coagulant to a ~elected poxtion of a deposition backing, at least partially drying the coagulant, depositing a layer of latex onto the backing to at least partially coagulate a selected portion of the latex layer, and ~hereafter concurrently drying or gelling the remainder of the latex layer and piercing only said remainder with 2 plurality of fluid jets to form pe.rmanent perforations therein. The patent to Hurt discloses method and apparatus for embossing plastic sheet material wherein a perforated base may be covered with a clo~h mesh which in turn may be covered with a plurality of intersecting threads to ereate a design. When suction is applied to the interior of the base~ the plastic sheet material brought in contact therewith is caused to assume the pattern inherent in the cloth and thread design. The patent to Smith et al. discloses method and apparatus for producing textured films. In the embodiment illus-trated in Figure 4, a woven wire mesh belt has super-posed thereon a specially patterned belt such that whenthe film being processed is subjected to vacuum it is caused to take an impression rom the patterned belt.
U.S. Patent 2,776,451 issued to Chavannes on January 8, 1957 also discloses apparatus and method 25 for producing embossed thermoplastic film. Chavannes discloses, in Figure 2, a perforated vacuum forming roll covered first with wire mesh and then with fabric.
Plastic film brought in corltact with the surface of the drum is embossed by Ineans of vacuum applied to the interior surface of the dxum.
U.S~ Patent 3,054,148 issued to Zimmerli on : September 18, 1962 discloses a process Eor producing a perforated thermoplastic sheet which comprises subjecting successive portions of a continuous sheet of -thermoplastic material to a uniform sotening treat~ent, passing the softened thermoplastic material into con~act with a continuously moving molding element perforated in accordance with a predetermined design, effecting selective plasticity of the sheet in eontact with the molding element, subjecting a surface o the thermoplastic sheet to the ac~ion of a fluid pressure differential to cause the softened material to flow into the perforations of ~he molding element, maintaining the pressure differential to effect rupturing of the thermopla$tic sheet in accordance with the perfora-tions in the molding element, subjectin~ the soft molded thermoplastic sheet to a fixing treatment, and continuou.~ly rem~ving the molded portions of the thermo-plastic sheet from ~he molding element. The molding element is perforated only in those areas where it is desired to perforate the plastic sheet and is solid in those ar~as where no perfoxations are desired.
U~S~ Patent 3,312,583 issued to Rochlis on April 4, 196-J discloses a pile-like molded product comprising a base having a plurality of parallel rows o~ pile formations of pyramidal shape integxally fonmed on and projecting from a surface thereof~ the formations of the respective transversely successive rows bei~ng staggered relative to one another i.n the longitudinal direction of said rows, said base having apertures therethrough separating some of the pile formation~ of the respective rows from one another, the apertures of a given row being in transvers~
alignment with pile formations of an adjacent row and being overlapped lon~itudin~lly by the ends of such pile foxmations, the respective pile formations of said given and adjacent rows also longitudinal~y overlapping one another to provide an integral connection of said respective pile formations at the --4~

overlapp d portions thereof. Rochlis discloses in Figures 21 and 22 mold cavities created by stacking laminar sheets upon one ano~her and enclosing the ends of the cavities by assembling the laminar sheets ~o a base lamination. Pile-like plastic products are formed by coatin~ the mold cavities thus produced with a softenable material, allowing the softenable material to set up, and stripping ~he resultant pile-like product from ~he mold cavity as generally shown in Figure 19.
U.S~ Patent 3,966~383 issued to Bussey, Jr~
et al. on June 29l 1976 disrloses yet another apparatus for vacuum forming sheet thermoplastic materialO ~he apparatus utili~es an endless, seamless structure as lS the fonming surface. A sheet of hea~ softened thermoplastic ilm is passed ovex a forming screen, the forming screen being supported by a support roll, a drive roll and two seal rolls. A vacuum is applied ~o the screen between the seal roll~ to pull the film into contact with the screen, thereby producing a three-dimensional pattern on the film corresponding to the outer surface of the screen.
, Commonly assigned U.SO Pa-tent 4,151,240 issued to Lucas et alO on ~pril 24, 1979 discloses ~till another preferred method and apparatus for debossing and perforating a running rihbo~ of thermo~
plastic film~ said paten~ being hereby incorporated herein by ref2rence. Briefly f the apparatus disclos2d in the Lucas et alO patent comprises means for contin~
uously converting a ribbon of thermoplastic film into a debossed and perforated film by directing hot air jets against one surfac~ of the film while applying vacuum adjacent the opposite surface of the film. The aforementioned operations a.re carried out while main~
taining sufficient control of the film to substantially obviate wrinkliny and/or macroscopically distending the film. In a par~icularly preferred embodimen~, the debossing and perforating means include a rotatably mounted debossing/perforating cylinder having closed ends, a nonrotating triplex vacuum manifold assembly and hot air jet meansO The film contac~ing surface of the debossing/perfora~ing cylinder exhibits the pattern to be impar~ed to the plastic film to be treated thereon.
In a particularly preferred embodiment of the Lucas et al. invention~ the debossing/perforating cyli~der is cGnstructed employiny a laminate formlng structure of the type generally described in Radel and Thompson, V.S. Patent 4,342,314, issued August lS 3, 1982. As ls pointed out in the specification of the aforesaid patent application, the laminate form-ing structure can be utilized to provide selec~ive aperturing of the plastic film, particularly in areas where ~luid permeabillty is desired, and debossing without perforating in ~hose areas where surface texture is desired but fluid permeability is undesirableO
Even with such improved forming structures, however, prior art means for selectively aperturing plastic films have historically been dependent upon such proces~ variables as the temperature of the film, the fluid pressure differential applied to the film and the speed of the overall operation.
Thus, heating the film to a greater exten~ in a preselected area where aperturing is desired has typically b~en employed to cause rupture of th~ film in the preselected area when the film is subjected to a uniform fluid pres-sure differential while it is in contact with the forming structure. An alternative prior art practice has been to apply a greater level of vacuum to those portions of a uniformly heated plastic web to be apertured. Unfortunately, the apertured regions created in the plastic Eilm by either technique are often poorly defined due to the difficulties associ-ated with uniformly controlling the process variablesO
This is particularly true in situations where ~heaperturing is to be carried out in A fine pattern, is irregular in shape and/or is discontinuous in the machine direction. Furthermore, such prior art tech-niques are impractical where it is desired to impart a uniform surface texture and appearance along the entire surface of the web with fluid permeability only at preselected points along the entir~ surface of the web.
A further dificulty inherent in such prior art processes is that aperturing of the film often results even where it is undesired, particularly where large, relatively weak, unsupported areas are to be debossed by the application of 1uid pressure thereto.
Accordingly, it is an object of the present invention to provide method and apparatus for accuratelydebossing and selectively aperturing a uniformly heated plastic web in nearly any desired predetermined pattern by subjecting the entire surface of said web to a uniorm fluid pressure differential on a forming struc-ture of the present invention.

It is yet another object of the present invention to provide a three-dimensional plastic film precisely apertured only at prede~ermined poin~s or in predetermined areas, said web exhibiting a substantially uniorm overall surface texture and appearance in bo~h the apertured and non-apertured areas thereof.

DISCLOSU~E OF THE PRESENT INVENTION
__ According to one aspect of the invention there is provided a continuous method of forming a plastic web exhibiting a substantially continuous three-dimensional pattern of debossments, a predetermined portion of said debossments being apertured a~ preselected points along the surface of said plastic web, said method comprisinq the steps of: (a) continuously bringing said plas~ic web in contacting relation with a tubular-shaped laminate forming structure exhibiting a substantially continuous first pattern of apertures corresponding to said deboss-ments and extending from the outermost to the innermost surface of said tubular-shaped structure, those apertures corresponding to the non-apertured debossments in said web having a perforate support member exhibiting a second pattern of apertures smaller in size than the apertures in said first pattern located interiorly of the outermost surface of said laminate structure, (b) heating the portion of said web in contact with said forming structure above its softening temperature: (c) applying a fluid pressure differential to said heated plastic web while said web is in contact with said forming structure to deboss said web in the image of said laminate forming structure where sa.id perforate support member contacts said web and to deboss and aperture said web in those portions of said forming structure where said perforate support member does not contact said web; (d) cooling said debossed and select-ively apertured web below its softening temperature; and (e) removing said debossed and selectlvely apertured web from s~id forming struc~ure.
According to another aspect of the invent.ion there is provided a continuous method of forming a plastic web exhibiting a substantially continuous three-dimensional pattern of debossments, a predetermined portion of said de-bossments being apertured at preselected points along the surface of said plastic web, said method comprising the steps of: (a) continously extruding a melt of plastic resin onto the periphery of a tubular-shaped laminate forming structure exhibiting a substantially continuous first pattern of apertures corresponding to said deboss-ments and extending from the outermost to the innermost of said tubular-shaped structure, those apertures correspond-ing to ~he non-apertured debossments in said web having a perforate support member exhibi~ing a second pattern of apertures smaller in size than the apertures in said first pattern located interiorly of the outermost surface of said laminate structure; (b) maintaining the portion of said plastic melt in contact with said forming structure above its softening temperaure; (c) applying a fluid pressure differential to said heated plas~ic melt while said web is in contact with said forming structure to deboss said melt in the image of said laminate forming structure in those portions of said structure where said perforate support member contacts said melt and to deboss and aperture said melt in those portions of said foxming structure where said perforate s~pport member does not contact said melt; (d) cooling said debossed and select-ively apertured melt below its softening temperature to form a web; and (d) removing said debossed and select-ively apertured web from sa.id forming structure, According to yet another aspect of the invention there is provided a plastic web exhibiting a substantially continuous three-dimensional pattern of debossments, a predetermined portion of said debossments being apertured at preselected points along the surface of said plastic web, said web being formed by- (a) bringing the plastic material comprising said web in contacting relation with a forming structure exhibiting a substantially continuous first pattern of apertures corresponding to said deboss-ments and extending from the web contacting to the non-web contacting surface of said forming structure, those - 8a -apertures corresponding to the non-apertured debossments in said web having a perforate support member exhibiting a second pattern of apertures smaller in size than the apertures in said first pattern located intermediate the web contacting and the non-web contacting surfaces of said forming structure; (b) applying a fluid pressure differen-tial to said heated plastic material while said plastic material is ab~ve its softening temperature and in contact with said forming struc~ure to deboss said material in the image of said forming structure in those portions of said structure where said perforate support member contacts said web and to deboss and aperture said material in those portions o:E said forming structure where said perforate support member does not contact said web; (c) cooling said lS debossed and selectively apertured material below its softening temperature to form said web; and (d) removing said debossed and selec~ively apertured web from said forming structure.
Other aspects of the present invention are disclosed in co-pending Canadian ~atent Application Serial No. 395,314 filed on February 1, 1982, of which the present application is a division.

The laminate tubular member permits continu-ous web processing. It is prefexably utilized in a vacuum forming operation which is conducted in concert with a curtain of hot air which flash heats either a plastic film or an extruded plastic melt suffi-ciently to effect substantial conformance to the three-dimensional pattern ernbodied in the tubular member when vacuum is applied to the interior surface thereof.
Thus debossing occurs across the entire surface of the plastic web, while debossing and aperturing takes place only in those areas where the apertures in said initially perforate planar sheet coincide with the pattern of apertures in one of the initially imperforate apertured sheets in the remainder of the laminate film forming structure. Tha support provided to the film by the non-coinciding portions of the initially perfor-ate, partially apertured sheet prevents rupturing of the film at the fluid pressures required to perforate the unsupported portions of the film. Thus, in the practice'of the present invention, a uniform level of vacuum may be employed across the entire surface of the tubular-shaped forming drum, and the temperature of the plastic web may be substantially uniform across its entire surface during the processing operation. ~nlike prior art techniques employing non-uniform fluid pres-sures and/or non-uniform web temperatures, precisely defined apertu.ring oE a web of plastic film in accord-ance with the present invention is controlled primarily by the character of the novel forming structure rather than by process variables~

BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concllJdes with claims particularly poin~ing out and distinctly claiming the present invention, i~ is believed the present invention will be be~ter understood from the follow-ing description in conjunction with the accompanying drawings in which:
Figure 1 is a simpll~ied perspective repre-sentation of an unfolded di~posable diapex with 10 portions of its components cut away;
Figure 2 is a plan view photograph enlarged approximately twelve times actual slze of the film contacting surface of a laminate ilm forming structure of the type generally disclosed in U.S~
Patent 4,342,314, said structure being comprised of a multiplicîty of initlally imperforate planar sheets having similar aperture pa~terns therein;
Figure 3 is a plan view photograph enlarged approximately twelve times actual size of a plastic film which has been caused to conform to a forming structure o~ the type generally illustrated in Figure 2, the apertured portions of the film having been created by the applicatio~ of a higher level of vacuum to the non-film contacting surface of the laminate structure;
Figure 4 is a plan view photograph enlarged approximately twelve times actual size o~ a selec~
tively apertured plastic film of the type shown in Figure 3 after removal from the laminate forming structure;

Figuxe S i5 a plan vîew photograph enlarged approximately twelve times actual size of a plastic film which has been caused to conform to a laminate forming ~tructure of the type generally illustrated in Figure 2, said film having been selectively apertured by elevating the temperature of the film in the areas where fluid permeability is desired and applying a uniform level of vacuum to the non-film contacting surface ~f the laminate structure;
Figure 6 is a plan view photograph enlarged approximately twelve times actual siz~ of a selec~ively apertured plastic film of the type illustrated in Figure 5 after removal from ~he laminate forming s~ructure;
Figure 7 is an enlarged, par~ially exploded, perspect.ive view of a laminate forming structure oE
the presenk invention, the lami~ae in the uppermost portions of said structure being explo~ed for clarity;
Figure 8 is a plan view photograph enlaryed approximately twelve times actual size of a preferred laminate forming structure generally similar to that illustrated in Figure 2, but incorporating the presen~
inven~ion to provide selective aperturing of a plastic ~ilm su~ected to a fluid pressure differential while in contact therewith;
Figure 9 is a plan view photograph enlarged approximately twelva times actual size of a plastic film which has been caused to conform to a lamina-te forming structure o the type generally illustrated in Figure 8 and selectively apertured in those areas where the initially perforate lamina has been apertured;
Figure 10 is a plan view photograph enlarged appxoximately twelve times actual size of a selectively apertured plastic film of the type shown in Figure 9 after rernoval from a laminate forming structure of ~he type shown generally in Figure 8;

Figure 11 is a perspective view of a tubular member formed by rolling a planar laminate structure of the type ~enerally illustrated in Figure 8 to the desired radius of ~urvature and joining the free ends thereof to one another;
Figure 12 is an enlarged~ simplified cross-sectional view ~aken along section line 12-12 of Figure 11 illustrating a preferred lap seaming tech-nique for joining the free ends of the laminate structure to one another without substantially disrupting the three-dimensional, selectively apertured pattern of the laminate structure in the area of joinder; .
Figure 13 is a view similar to that of Figure 12 illustrating yet another lap seaming tech-nique which can be used to join the free ends of the laminate structure to one another withollt suhstantially disrupting the three~dimensional, selectively apertured pattern in ~h~ area Qf joinder; and Figure 14 is a simplif.ied schematic illus-tration of a method and apparatus for debossing and selectively aperturing a plastic film generally in accordance with the present invention.

DET~ILED DESCRIPTION OF THE PRESENT INVENTION
While the present invention will be described in the context of providing a uniformly textured, but selectively apertured top sheet on an absorben~ bandage such as a disposable diaper, the present invention is in no way limited to such applica~ion. To the contrary, the present invention may be practiced to great advan-tage in many situations where it is desired to produce a plastic film or web exhibi~ing a uniform three-dimen-sional pattern across its entire surface, bu~ which is pervious to the passage of 1uid and/or gas only at pre-~5 determined points along the entire surface of the web or in certain preselected areas of the web. The pattern of apertures created may be of any desired shape, they may be regulated or random, reticula~ed or nonreticu-lated, continuous or interruptedy or any desired combination thereof. ~he detailed description of the preferred structure and its use as a top sheet in a disposable diaper will allow one skilled in the art to readily adapt ~he invention to o~her devices.
Figure 1 is a perspective view of a disposable diaper in an unfolded condition. Various layers have been cut away to more clearl~ reveal the structural details of this embodiment. The disposable diaper is referred to generally by the reference numeral 1. The top sheet is shown at 2~ The other two major compon-ents of the disposable diaper 1 are the absorbent element or pad 3 and the back sheet 4, which is pref-erably resistant to the passage of absorbed fluids~
In general the side ~laps 5 of the back sheet 4 are folded so as to cover the edges of the absorbent pad 3 and top sheet 2. Top she~t 2 is generally folded to completely enclose the ends of the absorbent pad 3, The drawing of diaper 1 in Figure 1 is a simplified representation of a disposable diaper. A more detailed description of a preferred embodiment of a disposable diaper is contained in U.S. Patent 3,952,745 issued to Duncan on April 27, 1976.
The illustrated diaper embodiment 1 shown in Figure 1 employs a selectively apertured plastic top sheet 2 which, when viewed by the user, exhibits a substantially uniform three~dimensional surface texture and feel across its entire surface. However, ~he top sheet 2 has been selectively apertured so as to be fluid-pervious only in the area generally designated as 7, while those portions of the top sheet ~enerally des i gnated as 6 r emai rl imper f or ate and consequently impervious to the passage of fluid.
Since the points of fluid entry are reasonably well defined in absorbent bandages such as disposable diapers, sanitary napkins, incon~inent pads and the like, selective aperturing of the top sheet only in those areas which are subject ~o the discharge of body fluids permits ~he discharged fluids to readily pass through the ~pertured portions of the top sheet and be absorbed within the absorbent element or pad 3.
Because the imperforate portions 6 of the top sheet 2 are impervious to the passage of fluids they completely preven~ reverse flow of the absorbed fluids back to the surface of the top sheet in contact with the wearer, even when subjec~ed to pressure caused by movements of the wearer. This provides more effective containment of the ab~orbed fluids as well as greater ovexall film strength in those axeas where fluid permeability is not essential.
Becau~e the,,disposable diaper 1 is less subject to rewet of it5 wearer contacting surace due to the limited size of the fluid pervious portion 7 of the top sheet 2 r the structure can be worn for longer periods to more effectively utilize the absorbent capacity o~ the absorbent element 3 without causing any increase in wearer discom~ort due to suxface wetness of the top ~heet 2 in the imperforate areas 6. Because the absorbent element 3 is constrained between the plastic top sheet 2 which is fluid-pervious only in area 7 and back sheet 4 which i5 also resistant to the passage of absorbed fluids, -the absorbed fluids are substantially prevented from esoaping along the periphery of the absorbent pad element 3, thereby preverlting wet-ting of garments coming .in contact with the edges of the diaper 1.

A further ad~antage of a selectively aper~
tured top sheet 2 of the ltype generally disclosed in Figure 1 is that i~ permits ready absorption of body fluids having an unpleasan~ appearance and thereafter masks the absorbed fluids from the user's view by means of the impexfcrate portions 6 surrounding the selectively apertured axea 7. Thus ~he user is able to fully utilize the absorbent capacity of the absorbent element 3 without encoun~ering the unsightly appearance typically exhibited by absorbent structures having their entire top sheets pervious to the passage of fluidsO
This factor is of particular significance where person~l care products such as sanitary napkins, surgical drapec, wound bandages, and the like are employed to transmit or absorb highly visible body exudates.
Selective aperturing in accordance wi~h the present invention is not, however, limited to the pro-vision of three-dimensional plastic webs havin~ prede-termined areas which are pervious to fluids, including gases. It may be applied to even greater advantage in situations whexe limited fluid permeabili~y is desired along the entixe surface of the web, e.g., in situa-tions where the points of fluid transfer~ whether in liquld or saseo~s ~orm, are not well defined. One illustra tive use of a three-dimensional film exhibiting limited fluid permeability over it~ entire surface might be as a breatheable back sheet for a disposable diaper. In such a situation, a three-dimensional d~bossed pattern may be applied to improve th~ visual and tactile impres-sion of the entire back sheet while selective aperturingmay be employed to provide limited fluid permeabili~y along the entire surface of the back sheet. By proper design, such a back shee~ can be made to permit vapor transfer therethrough yet avoid fluid leakage.

46~
~16-As has been pointed out earlier herein, means for debossing and selectlvely aperturing moving plastic webs are well known in the art. ~ypically, these prior art means involve applying a greater fluid pressure differential, most typically vacuum, to those por~ions of the web to be apertured whiLe said web is at a sub-stantially uniform elevated temperature and in contact wi~h a forming s~ructure~ Al~ernatively, the plastic film may be selectively heated to a greater extent in those areas where apertures are desired~ such that the film is more prone to rupture in the elevated tempera~
ture areas when subjected to a substantially uniform fluid pressure differen~ial on a forming structure.
If desired, non-uniform heating of the plastic web and the application of non-uniforrn fluid pressures to the web may be used in conjunction with one another.
However, it has generally be2n found that the greater ~he number of process variables to be controlled, the greater will be the difflculty ln producing consistent results in the film~ Furthermore, such prior art selective aperturing techniques are not practical where only predetermined points along the entire surface of the web are to be made fluid perviousO
Figure 2 is a plan view photograph enlarged approximately twelve times actual size of a laminate forrning s~ructure made generally in accordance with the teachings of U.S. Patent 4,342,314. Briefly~ the laminate forming structure 10 wa5 formed generally in accordance with the teachings of said patent application by photoetching six identically patterned stainless s~ee.l sheets, each sheet having a thickness of about five mils, copper plating the exterior surfaces of the individual stainless steel sheets with a coating S approximately 0.1 mils thickl and thereafter furnace brazing the sheets to one another at a temperature of a~out 2~050F while said sheets wex~ secured in a stacked condition so that their aperture pat~erns are aligned in superposed relation with one another to form a fine scale perforate forming surface exhibiting a multiplicity of irregularly shaped apertures, i.e., 15, 16, 17~ 18, 19, 20, 21, 22, etc.
The uppermost surface 11 of the laminate forming structure 10 exhibits a plurality of striations 12 across its entire surface to provide surface imperfections which tend to minimi2e any resultant gloss in plastic films subjected to a orming opera~ion thereon. This is preferabl~
accomplished by striating the resist coating on the uppermos~ lamina during ~he photoetching process, as generally disclosed in the aforementioned patent application of Radel et al.
In Figure 3 there is shown a selectively apertured 1.4 mil thick polyethylene plastic film 30 which has been simultaneously subjected to two different levels of fluid pressure, iOe., vacuum, while in contact with a lamin~te forming structure 10 of the type generally illustrated in Figure 2.
The condition of the film 30 is shown in Figure 3 prior to removal from the forming structure 10~
The film illustrated in Figure 3 was produced by.uniformly heating the ilm across its entire surface to a t~mperature of approximately 400F. Those portions of ~he film to the left of dividing line 2~, which deines the approximate line of separation b~tween the apertured and non-apertured portions of the film, were subjected to a vacuum of approximately 17 inches of mercury applied to the lowermos~ surface of the formi~g structure 10, while those portions to the right of di~iding line 24 were subjected to a vacuum level of approximately 4 inches of mercury.
The lower level of vacuum applied to the righthand portions of the heated web was sufficient t~ cause substantial conformance between the pla6tic film 30 and the forming structure 10/ yet insufficient to cause wide scale aperturing of the film in the irregularly shaped debossed areas of which 19', 2n~ ~
21' and 22' are..typical. As will be apparent from a comparison of Figures 2 and 3, the pattern formed by debossed areas 19' through 22' in the film 30 corres-ponds to the pattern formed by aper~ures 19 through 22, respectively, in forming structure 10. Conversely, the higher vacuum level applied to that portion oE film 30 to the left o~ dividing line 24 was suficient to cause not only debossing but also rupturing of ~he film to form apertures of which 15', 16', 17' and 18' are typicalO As with the non-apertured portions of the ilm 30~ the pattern formed by apertures 15' through 18' in th~ film 30 corresponds to the pattern formed by apertures 15 through 18, respectively~ in forming structure 10.
Figure 4 is a plan view photograph enlarged approximakely twelve times actual size of a ~electively apertured plastic film 30 of the type generally illu5-: 30 trated in Figure 3 after removal from the laminat~
forming structure 10.
Figure 5 is a plan view photograph enlargedapproximately twelve times actual size of an alterna-tive selectively apertured lo 4 mil thick polyethylene plastic film 40 also fonmed by applyi~g a fluid pressure differerltial to the film while in contact $

with a forming structure of the type generally illus-trated in Fi~ure 2. In ~igure ~ the film 40 i5 shown in contact with the forming structure. The imperforate portions of the film to the righ~ of dividing line 41 were elevated to a temp~rature o~ approximately 300~
while the apertured portions of the film to the left of dividing line 41 wexe elevated to a temperature of approximately 750F. A vacuum level of about 6 inches of mercury was applied to the entire lowermost sur~ace of the forming structure 10 while the heated film was in contact thexewith.
As can be seen in Figure 5, the higher temper-ature of those portions of the film 40 to the left of dividing line 41 ~ufficiently weakened the film to allow rupture and formation of fluid-pervious apertures such as 15", 16", 17" and 18" therein~ Those portions of the fi~m 40 to the right of dividing line 4]. were caused to confor~ to the laminate forming structure 10, but due to the lower.temperature o~ the film, fluid-2Q impervious debossed areas such as 19", 20", 21" and 22"
were created instead of apertures. A comparison of Figures 5 and 2 reveals the pattern correspondence between film apertures 15" through 18" and foxming structure apertures 15 through 18, respectively as well as between debossed areas 19" through 22" and forming structure apertures 19 through 22, respe~tively~
Figure 6 is a plan view photograph en].arged approximately twelve times actual si~e of a selectively apertured plastic film 40 of the type generally shown in Figure 5 after removal from a laminate forming structure o~ the type generally illustrated in Figure

2. As can be seen from Figure 6, separation between the apertured and non-apertured portions of the f.ilm 40 is approximately alony dividing line 41, which substantially colncides with the line along which differential temperatures wexe appli~d during processing.

Figure 7 is a ~impllfiedr partially exploded, per-spec~ive illustration of a partlcularly preferred photo-etched lalninate forming structure 120 of the present invention. The laminate structure 120, which is prefer-ably constr~cted generally in accordance wi~h ~he teach~
ings of the aforemen~ioned U.S. Patent 4,342l314 is comprised of a stack of individual sheets or la~inae 130l 131, 132, 133, 134 and 135, Each lamina has a pattern of openings or apertures therein. The laminae may be made from any suitable material capable of being apertured and bonded. Stainless steel is parkicularly ~referred where the laminae are to be apertured by photoetching and bonded by co.pper plating and furnace brazing.
As will be apparent from Figure 7, laminae 132, 134 and 135 are identical to one another. If desired, all laminae in a given forming structure may employ an iden-tical pattern of apertures. This is the case with the forming structure embodiment 10 illustrated in Figure 2 However, if a network of decreasing capillary size is desired, it is necessary to employ coincidin~ apertur~s of decreasing size in ~uccessive laminae or to further subdivide the aperture patkerns in the direction of the lowermost surface of t.he structure. In ~he latter case, which is illustrated in Figure 7, it i5 typical to employ several identical laminae superposed upon one another to provide sufficient depth of pattern in each dissimilar portion of the laminate structure. However, for simpli-city of illustration a single uppermost lamina 130 and a single intermediate lamina 131 are shown Lamina 130 exhibits a patterned arrangement of irre~lar openings 150, 160, 170 which when superposed on lamina 131 align generally with the peripheral border formed by each pair of openings 151~ 152; 1610 162; and 171~ 172, respectively.
Similarly, the peripheral borders ~ormed by each group of openings 153, 154, 155 and 156; 163, 1~4~ 165 and 166~ and 173, 174, 175 and 176 in lamina 132 are generally aligned with the peripheral border formed by openings 151, 152;
161, 162; and ~71, 172, respectively, in lamina 131. From the ~oregoing descripkions, it is readily apparent how intricate three-dimensional geometric ~tructure~
exhibiting a continuous capillary network of decreasing size in the direction of the lowermo~t surface o~ the $
~21-.~
structure can be created~ Utilizing the technique set orth in detail in the aforementioned U.S, Patent 4,342,314, nearly any three-dimensional pattern which is desired may be created.
As will be apparent rom an inspection of Figure 7, laminae 130, 131, 132, 134 and 135 are Eormed from a planar sheet which is initially imperforate in accordance with the teachings of the aforementioned application of Radel et al.
For eace of fabrication lamina 133 may, if desired, be formed from a planar shee~ inltially con~aining a closely spaced pattern of small perforations 180. Al~ernativelyr the pattern of apertures or perfora~ions 180 may be formed simultaneously with the pattern of coinciding apertures 163', 164', 165', 166', 173l, 174', 175', 176~, etc.
As will be readily apparent from Flgure 7, a por-tion of the small perforations 180 in lamina 133 are placed in fluid communicakion w~th certain of the apertures in uppermost lamina 130, e~g~ aperture 150, while the remain-ing aper~ures 163', 164', 165', 166', 173' t 174', 17S' and 176' in lamin~ 133 are placed in fluid communica~ion with other discrete apertures in uppermost lamina 130, e~g., apertures 160 and 170, The fluid communication provided between perforations such as 180 and apertures such as 150 permits debossing without aperturing of a heated plastic web subjected to a fluid pressure differential in those areas where the web contacts and is supported by lamina 133. Conversely, the fluid communication provided between apertures such as 163l, 164~, 165', 166', 173', 174', 175' and 176 ' in lamina 133 and apertures such as 160 and 170 in lamina 130 permits debossing and aperturing of a heated plastic web subjected to a fluid pres~ure differential in those areas corresponding to apertures 163', 164', 165', 166'~ 173', 174', 175' and 176'f since the web doe~ not receive any support from lamina 133 ln those areas.
To provide support to the ilm or melt being proces sed on a forming structure of the present invention, the perforations 180 must be generally smaller in size than the apertures to be produced in the filmO Experience wi~h perforations and film apertures having a maximum to minimum dimension ratio în the neighborhood of l:lt respec~ivelyt has shown that un~santed rupturlng of the film may norrnally be avoided when the maximum dimension of the individual perforation, e.g., ~he diame~er of perforation 180, in lamina 133, is not more than about 25 percent of the maximum dimension of the smallest aperture to be formed in ~he resultant ilm, e.g., the maximum dimension of the film aperture corresponding to s opening 174' in lamina 133.
Spacing of the individual perforations, such as 180, must be sufficiently frequent that conformance of the film to the fonming structure will be achieved when suction is applied to the lowermost surface thereof. Accordingly t the particular pattern of perforations to be employed in those portions of lamina 133 used to form the debossed, non-apertured areas of the ~ilm will depend upon the oomplexity, siæe and depth of the debossed areas desired in the resultant film.
In the illustrated embodiment, lamina 133 is preferably photoetched with a pattern of apertures 163', 164', 165', 166', 173l, 174', 175' and 176t correspond-ing to apertures 163t 164, 165, 166, 173, 174, 175 and 176, respectively in lamina 132. These are the areas in which aper~uring of the plastic f.ilm is desired.
Where debossing of the.plast.ic film without aperturing i5 desired, the sheet from which lamina 133 is formed, which ini a particularly preferred embodiment is initially perfoxate, is not photoetched to coincide with the pattern of apertures present in the adjacent lamina, e.y., apertures 153, 154, 155 and 156 in lamina 13~.
In an alt~rnative embodiment lamina 133 may be constructed from more than a single sheet by splicing a lamina such as 132 with a sheet of perforate material such as the non-apertured portion 181 of lamina 133 in butt joint fashion along any desired line of demarcation between the areas of the film to be debossed only and the areas to be debossed and apertured.

~5~

-23~

Where the individual laminae are very ~hin, it may also be feasible ~o comple~ely remove the areas to be apertured from lamina 133 along theix peripheral borders and leave the adjacent laminae, in the illus-trated case 132, 134, unsupported by l~nina 133 in saidareas. This particular method W2S employed în con-structin~ laminate forming structure 210 illustrated in Figure 8.
In still another embodiment, a selectively apertured lamina such as 133 could be employed as the lowermost member of the laminate stack. In such case, those portions o lamina 133 corresponding to the pattern in the resultant ~ilm would be removed from the lamina. By maintaining the selectively apertured lamina 133 independen~ fxom ~he balance of the laminate structure, the pattern of selective aperturing to be imparted to the film could be changed merely by changing the selectively apertured lamina.
Practice of the present invention offers a further advantage over prior art techniques where de~ossing of the plastic film to different depths is desired. In such a situationl a selectively apertured, lamina may be incorporated at more than one level within the forming structure to provide multiple levels of debossing and selective aperturing in the resultant filmO
Regardless of the particular fabrication method chosen for constructing the selectively apertured lamina 133 illustrated in Figure 7l the resultant laminate film forming structure 120 is preferably subjected to a uni~orm ~luid pressuxe differential while an initially impexforate web of plastic film of substantially uniform temperature i5 in contact with its upper~ost surface~ As has been pointed out earlier herein, said web may be fed in film -2~-form from a supply roll, or extruded as a melt directly onto a forming structure of the presen-t invention. Regardless of which form of plastic introduction is employed, the fluid pressure differ-ential causes the heated film to conform thereto alongits entire surface. Because of the support provided to the film by the unetched perforate portion 181 o lam:ina 133, the film is caused to conform to the laminate forming structure 120 without rupturing.
However, in those areas of the orming structure 120 wherein lamina 133 exhibits coinciding apertures 163l, 164', 165', 166', 173', 174', 175i and 176', debossing and rupturîng of the film in accordance with said pattern of apertures occurs.
Vertical or z-direction placement of a selectively apertured lamina, eDg., lamina 133, in a laminate forming structure of the present invention controls the depth of draw in film processed thereon~
However, improper z-direction placement can also cause unwanted aperturing of the ilm to take place. If the selectively apertured lamina is placed too grea~ a distance from the uppermost surface of the lc~mina, ~he film will be unable to obtain any support prior to rupturing. On the other hand, if a selectively apertured lamina is placed too near the uppermost surface of the laminate ~orming structure, the depth of debo~s in the resulting film may be insufficient to produce a uniform appearance across both the apertured and nonapertured areas o~ th~ web. The particular z~direction placement of ~he selectively apextured lamina i5 dependent upon a number of variables which must be taken into consideration in order to obtain the desired resul~s. Several o~ the more important factors are:

(a) the rheological properties of the base plastic material to be processed;
(b) the temperature of the plastic material at the deormation stage;
(c) the rate of deformatlon;
(d) the size and geometry of the apertured and non~apertured deEormations to be produced in the web; and (e) the temperature of the lamina~e forming structure~
The rheological properties of the plastic material which are of primary interest in the present context are the "relaxation ti~.e" of the material, as generally described at pages 90-95 of the 1971 edition of Mechanical ProPerties of Solid Polymers, I . M O Ward John Wiley ~ Sons, New York, and the "elongational viscosity" of the material, as generally described at pages 184-190 of the 1979 edi tion of Princi~ of Pol~mer Processing, Z. Tadmer and C~ Gogos, John Wiley & Sons, New York. The relaxation time is a character-istic time constant for the decay of stress with time in a material, while the elongation viscosity is a measure of the resistance of a material to rate of deformation under pure normal stxess. In general, experience has ~hown that for materials having shorter relaxation times and lower elongational viscosities, a grea~er draw of the material is possible prio.r to rupture a Thus, Z-direc'cion placement depth of the selectively apertured lamina may generally be ir.creased for such materials.

-2~-As the temperatuxe of the plastic material and the laminate forming s~ructure are increased~ it has generally been found easier to draw the material without rupture. Accoxdingly increased temperatures generally permit greater Z-direction placement depths ~or the selectively apertured lamina.
Conversely, the greater the rate of plastic deforma~ion the more difficult i~ is to draw the material wi~hout rupture. Therefore, shallower 2-direction placem~nt depths are generally preferred as formation rates are increased.
~ inally, the size and geometry of the par-ticular deformation will greatly affect Z-direction placement depth for the selectively apertured lamina.
E'or apertures having length to width ratios approaching unity, the largex the size of the aperture, the shallower should be the depth of placement. Similaxly, the more tortuous and irregular the geometry, the shallower should be t~e depth of placementa It will of course be recognized by those skilled in the art that these critexia must be con-sidered on a case by case basis to arrive at optimum Z-direction placement of the seleGtively apertured lamina for any particular situation.

Since the draw depth of the film can be controlled b~ appropriate Z-direction placement of selectively aperturQd lamina 133, as described earlier herein, selective aperturing of the plastic film at predetermined points or in predetermined areas may likewise be precisely controlled without ~he need to apply differing levels o fluid pressure to the lower-most su.rface of the forming structure and without the need to heat the film to differing temperature levels across its sur~ace. Accordingly, the present inven tion permits overall three-dimensional texturing of a moving plastic web in combination with selective aperturing of predetermined points or areas of said weh. The apertured points or areas may be of any desired shape, isolated o~ non-isolated from one another and continuous or disconkinuous in the direc-tion of web processiny. As will be appreciated by those skilled in the artt these objectiv~s are extremely dif~icult, if not impossible, to achieve by : 20 prior art variable vacuum and variable temperature techniques.
In addition to the foregoing advantages, it should be noted that practice o the present inventi.on ofers ~nother benefit not provided by prior art seiective aperturing techniques. Namely, in situations where individual non-apertured debossments which are very large in siz~ are desired, it is extremely diffi-cult to completely deboss the plastic material without causiny rupture thereof. This i5 due to the lack of ~ film support across the large discrete areas to be debossed. Employing a lamina exhibiting a ine scale pattern of perforations, e.g~/ perforations 180 in portion 181 of lamina 133/ in a laminate forming struc-ture of the present invention provides localixed support to -the film during the debossing operati.on..

-~8- ~

Such a lamina, which in a particularly preferred embodiment is selectively apertured, permits effec-tively debossing the film ~o nearly any desired dep~h in patterns employing very large d~bossments without causing undesired rupture thereof.
While proper Z-direction placement of the selectively apertured lamina, e.g., lamina 133, is necessary ~o effectively control aperturing of the film, it should be noted that it is also preferable in the practice o~ the present inven~ion to prevent the portions of the film which are apertured from wrapping abou-t the lowenmosk surface of the foxming structuxe upon rupture. ~his avoids mechanical locking of the film to the forming structure, thereby making removal of the film from the forming structure relatively easy. In a particularly preferrèd embodi-ment of the present invention this may be accompllshed by providing additional laminae~ e.gO, laminae 134 and 135, below the selectively apertured lamina. These additional laminae prevent the ruptured portions o~ the film rom reaching the lowermost surface of the laminate forming structure.
Figure 8 is a plan view photograph enlarged approxi~ately twelve times actual size of a preferred laminate film forming structure 210 of the present invention. The laminate film orming structure ~10 is in most respects similar to the laminate film oxming structure 10 illustrated in Figure 2, i.e.~ a random pattern of capillary networks, each defined by a multi-plicity o interconnected ~iber-like elementsO It was created by superposing a stack of laminar sheets upon one another with their aperture patterns in ver~ical align~
ment, the assembled stack being bonded in accordance ~ith the teachings of the aforementioned application of Radel et al. to form an integral la~inate ~tructure.

When viewed from the plan, the fully apertured po-tion of the laminate film forming s~ructure 210 to the left of dividing line 241 appeaxs essentially the same as the fully apertured laminate film forming structure 10 illustrated in Figure 2. A random pattern of capillary networks comprising apertures, e.g., apert~lres 215 through 218, propayates all the way from the uppermost surface 211 ~o -~he lowermost surface of the lamina~e s~ruc~ure 210. In this regard, note the patt~xn similarity to apertures 15 through 1~, respec~ively, in laminate forming structure 10 shown in Figure 2.
The uppermost lamina of structure 210 is provided with a multiplicity of grooves 212 generally similar to the grooves 12 in film forming structure 10 to provide desired surface roughness. That portion of the structure 210 to the left of dividin~
line 241 corresponds to that portion of the plastic film to be apertured. Conversely, that portion of the forming structure 210 to right of dividing line 241 is provided with a perforate but unetched lamina 233 intermediate the uppermost and lowermost lamina.
This prGvides a supporting surface for those por-tions of the plastic film to be debossed but not apertured.
The regulated pattern of perforations 280 in the unetched portion 281 of lamina 233 permit the application of uniform fluid pressure, preferably vacuum, to the lowermost surface o~ the heated plastlc film bxought into contact with the forming str~cture 210, thus providing effective debossing of the film in those areas where aperturing is not desired. Those portions of the film which are unsupported by the perorate portion 281 of selectively apertured l~mina 233, i.e.~ those portions to the left oF dividing line 241, are not only debossed, but apertured as well~

~s shown in Figure 9, appliGation o~ a uniform lcvel of vacuum to the lowermost suxface of forminy struc-ture 210 will produce a selectively apertured plastic film 320 exhibiting a substantially uniform three-dimensional texture across its entire surface.
In a particularly preEerred embodiment of the present invention, the laminae used to construct laminate forming structure 210, including selectively apertured lamina 233, are created by means sf highly versatile photoetching techniques. These techniques make it feasible to precisely contxol the areas to be apertured and the areas to be debossed but not apertured in the resultant plastic film. Depending upon the size and frequency of the debossments, it may also be feasi~le to create laminae suitable for use in forming structures of the present invention by more conventional techniques, e.g., punching, stamping, non-contact machining, etc.
Figure 9 is a plan view photogr~ph enlarged approximately twelve times of a 1.4 mil thick poly-eth~lene plastic film 320 which has been debossed and selectively apertured in accordance with the present invention on a lamînate film orminy structure of the type yenerally illustrated in Figure 8~ Those portions of the film 320 to the left of dividing line 241, which coincides with the edge of perfo-ate lamina 233, exhibit aperkures, i.e., 215', 216', 217', and 218' corresponding ~o apertures 215, 216, 217 and 218, respectively, in forming structure 210. Those portions of the film 320 to the right of dividing line 241 exhibit debossed, but non-apertured areas, i.e., 250', 251', 252' a~d 253l corresponding to aperkures 250, 251, 252 and 253, respectively, in forming structure 210. The film 32Q shown in Fiyure 9 is still i.n c~ntact wi-th a formilly surface 210 of the type generally shown in Figure 8. The majority of dark spots 380 in those portions of the film to the riyht of dividing line 241 are not perforations, but are due partially to background visibility of the perforations 280 in selecti~ely apertured lamina 233 and partially to a degree o~ film deformation S which took place during the forming operation. This is somewhat more apparent from Figure 10, wherein a selectively apertured film 320 of the type shown in Figure 5 has been removed from th~ ~orming structure 210.
Because the photoetching technique utilized to create preferred forming structures of the present invention can be practiced on an extremely fine scale, it is difficult to discern any difference in texture and appearance between the apextured and the non-aper-tured areas of the film 320 when viewed at actual size by the naked human eye. This difference becomes even less apparent when the selectively apertured film i5 utilized in applicatîons such as a diaper or a sanitary napkin top sheet, wherein the absorbent material located beneath the apertured portion of -the plastic film 32Q exhibits a color generally s:imilar to that o~ the film.
In a particularly pxeferred embodimen~, selectively apertured, laminate forming structures of ~he presen~ invention axe rolled by conventional ~echniques into tubular forming members 460, as generally illustrated in Figure 11~ Contrary to expectations, it has been determined that rolling the planar laminate structure, which is preferably constructed generally in accordance with the teachings of ~he aforementioned co-pending commonly assigned patent application of Radel et al., into a tubular shape does not tend to cause delamination of the structure, provided the furnace brazing operation utilized to join the lamina has been properly carried out. Where ex~remely intrica~e patterns are present in the laminate structure~ it has been learned that placing a thin sheet of urethane on opposite sides of the laminate structure as it is passed through the metal rolls will minimize the chance Qf injury to the fine pattern while rolling the member in~o the desired tubular s hape O
The outermost surface 464 of the tubular forming member 460 is utilized to deboss and selectively aperture plastic film webs brough~ in contact there-with while the innermos~ surface 465 of the tubular member generally does not contact the plastic web during the forming operation. As shown in Figure 11, those portions of the plastic web to be apertured contact the tubular member a~ areas 470 where the selectively apertured lamina contains a pattern of a~ertures coinciding with that of the other laminae in the forming structurel while the remaining portions of the laminate forming structure represent the areas 20 where the selectively apertured lamina does not contain a pattern of apertures coinciding with the pattern of apertures in the other lami~ae. Thus, while the overall surface of the film will be _aused to exhibit a substantially uniform three-dimensional texture and appearance, only those port.ions 470 will be apertured.
The tubular member 460 ~enerally shown in Fi~ure 11 may, in a preferred embodiment of ~he present invention, be employed as the forming ~urf~ce on debossing/aperturin~ cylinder 555 in a process of the type generally illustrated in Figure 14, said process being described in detail in U.S. Patent 4~151,240 issued to Lucas e~ al. on April 2~ 19790 $

Laminate fabricating techniques provide the ability to join the free ends of a single formîng : section to one another or the ability to join one forming section to ano~her orming section of similar pattern with substantial continuity in the selectively apertured three-dimensional pattern ~hroughout the structure in the area of joinder. The laminating technique may also b~ employed to advantage to join a multiplicity of small ~orming seotions to one another where, for one reason or another, it is impraotical to in~egrally for~m the individual lamina in large enough si~e.
Figure 12, which is a simplified cross-sectional view taken along section line 12-12 of Figuxe 11, illustrates one preferred manner of joining the free ends of tubular member 460 to one another to provide an integral tubular st.ructure exhibiti.ng substantially no discontinuity in the selectively apertured, three-dimensional pattern in the a.rea of joinder. In the embodiment shown in Figure 12, a lap seam is created by allowing each free end of the planar photoetched laminate structure from which tubulax,member 460 is formed to project in a manner

-3~-resembling a series of parallel stairsteps. The stair-step ed~es may be provided by properly stacking the laminae prior to bonding, or by non-contact machininy techniques after the structure has been bonded. Since tne pattern exhibited by each photoetched lamina is precisely regulatQd and highly repeatable, rolling .the planar laminate structure .into a tubular shape causes the mating free Pnds to align with one another in stairstep fashion as illustrated in Figure 12.
Thus, if ~he slight differences in radius of ourvature or each successive lc~mina in the stack are ignored, corresponding parts of the pattern employed in lamina 570 mate with one another at 571; corresponding parts o the pattern employed in lamina 572 mate with one another at 573; corresponding parts o~ the pattern employed in lamina S74 mate with one another at 575i corresponding parts of the pattern employed in lamina 576 mate with one another at 577; corresponding parts of th~ pattern employed in lamina 57~ mate with one 20 another at S79; and co.rresponding parts of the pattern employed in lamina 580 mate with one another at 581.
As is apparent from Figure 12, no individual lamina seam is radially aligned with another, yet the selective-ly a~e.rtured three-dimen~ional pattern of the tubular member 460 existiny between the outermost surface 464 and the innermost surface ~65 is substantially identical at any point along the pexiphery of the tubular member, including the area of joinder. Furthermore, the resultant seam ha~ much greatex ~trength than a radially aligned butt joint du~ to the rein-Eorcing effect of one lc~mina on its adjac~nt lamina. Joinder of the lap seam shown in Figure 12 is preferably carried out by applying a low melting po.int bonding alloy to ~he area of joinder utilizi~g either a torch or a brazing furnace, as generally described in the a~orementioned co-pending commonly assigned patent application of ~adel et al. The low melting point metal bondiny ~lloy bonds itself to the laminate structure without creating a substantial discontinuity in the area of joinder while at a temperature which is sufficiently low that it does not adversely afect the copper bonding within the structure per seO Al~ernatively, the joint could be ~urnace brazed in the same manner ~he laminate structure is bonded together, provided the areas outside the joint are pro~ected against excessive hea~.
Figure 13 is a view similar to that of Figure 12, but illustrating yet another lap seaming technique which may, if desir~d, be employed to join the free ends of laminar structures of the present invention to one anotherO Care must, however, be exercised with the construction generally illustrated in Figure 13 to prevent non-adjacent lamina from 15 bonding to one ano~her at their free edges during the furnace brazing operation while the laminate structure is in planar condition. One method of avoid~
ing such problems is to temporarily insert thin ceramic paper intermediate the non~adjacent lamina at the exposed edges during the planar phase of the furnace bxazing operation.
In the tubular embodiment of Figuxe 13, the free ends of tubular element 460l are interleaved with one another such that, if the slight differences ~5 in radi~s of curvature for each successive lamina in the stack- are ignored~ corresponding portions of the pattexn conta.ined in lamina 570' are mated ~o one anothex at 571'; coxresponding portions of the pattern contained in lamina 572' are mated ~o one ano~her a~
5731; corresponding portions of the pattern contained in lamina 574' are mated to one another a~ 575';
corresponding portions of the pattern contained in lamina 576' are mated to one another at 577';
corresponding portions of the pa~ern con~ained in lamina 578' are mated to one another at S79'; and corresponding portions of the pattern contained in lamina 580i are ma~ed to one another at 581'. Thus, no lamina seam i5 in radial alignment with an adjacent lamina seam, yet the three-dimensional, selectively apertured pattern existing between the outermost surface 464l and the .innermost surface 465' of the tubular member 460 ' is sub~tan~ially continuous a~ any point along the periphery of the drum, including the area of joinder of the free end~.
Thusr a cylindrical forming structure exhibiting substantial continuity of pattern along its entire periphery is provided. This permits continuous form-ation of a plastic f ilm web exhibiting the desired selectively apertured, three dimensional pattern without a seam discontinuity of the type typically present in prior art forming struc~ures, As will be readily apparent to those skilled in the art, the present invention may be applied to great advantage to produce selectively apertured plastio webs exhibiting nearly any three dimensional pattern, char~cteristic, property or appearance desired.
As will be appreciated by those skilled in the art, the fabrication and bonding techni~ues decribed above de~ine particularly preferred embodiments of the present invention. Dependlng upon where the selec-tively apertuled lamina is posltioned in relation to other laminae in the stack, it may be feasible to leave those laminae located intermediate the selectively apertured lamina and the outermost surface of the tubular member unbonded to said selectively apertured lamina. In such an arrangement, changing said outer-most laminae as an integral unit would readily permit changing the three-dimensional pattern of embossments ~ 37 -to be imparted to the web while maintaining the same line of demarcation between the apertured and non-apertured areas.
The inherent flexlbility of photographic tech-niques makes it feasible to create nearly any structure desired by designing the particular characteristics sought into each layer and thereafter photographically reducing or enlarginy t~e size o the pattern to what-ever scale is desired in the photoetched lamina~ In other embodiments of the present invention photographs of existing structures exhibiting desirable character-i.~tic~ could ~e util1zed to form one or more o the photoetched lamina. A composite s~ack comprised of individual lamina of varying patterns and including at lS least one selectively apertured lamina of the present invention may thereafter be assembled generally in accordance with the teachings of the aforementioned application of Radel et al. to produce a laminate form-ing s~ructure exhibiting characteristics and properties not achievable by prior art means~
A particularly preerred continuous process for forming debossed, selectively apertured plastic films which may employ a tubular laminate forming structure of the type generally shown in Figures 12 and 13 is schematically illustrated in Figure 14. This process i5 generally ~escribed in UOSO Patent 4,151,240 issued to ~ucas et al~ on April 24, 1979~ A particularly preferred apparatus 540 o~ the type disclosed in said patent is schematlcally shown in Figure 14? It includes constant tension film supply means 541, debossing and aperturing means 543~ and constant tension film :Eorwarding and winding means 545~ The frame, bearings, ~upports and the like which must ~38-necessarily be provided with respect to the function~l members of apparatus 540 are not shown or described in detail in order to simplify and more clearly disclose the presen~ invention, it being understood 5 that such details would be obvious to persons of ordinary skill in the film converting machinery art.
Briefly 9 apparatus 540, Figure 14, com-prises means for continuou~ly converting a ribbon of thermoplastic film 550 into a debossed and selectively apertured film by directing hot air jets against one surface of the f ilm while applyirlg vacuum adjacent the opposite surface of the film, and while maintaining su~ficient control of the ilm 550 to substantially obviate wrinkling and/or macroscopically distending the film. Thus, as will be more fully described hereinafter, apparatus 540 comprises means for maintaining constant machine direction tension in the film both upstreclm and downstream of a æone where the temperature is ~0 gxeater than the softening temperature of the ilm, which is typi~ally its thermoplastic temperature, but in which zone there is substantially zero machine direction and substantiall,y zero cross-machin~
direction tension tending to macroscopically distend the film. The tension is required to control and smooth a runnlng ribbon of thermoplastic film; the zero ten~ion zone results from the film in the 20ne beins at a temperature suf~icien~ly high to soften the film and thereby enable debossing and, where d~sired~
aperturing thereof via the applica~ion of vacuum ~o the interior surface o the laminate tubular member.
Figure 14 has been greatly enlarged and partially broken away to enable visually p~xceiving the nature of the differenc~ betw~en the debossed but non-apertured portions 590 and the debossed and apertur~d portions 591 of the film 550, as more fully described hereinafter. The debossed but non-apertured por-tions 590 of the film 550 are formed by ~hose portions of tubular forming structure 460 which correspond to the non-coinciding portions of the selectively apertured lamina, while the debossed and apertured portions 591 of the film correspond to those portions 470 of the tubular forming structure which contain the coinciding portion of the selectively apertured lamina.
As can be seen in Figure 14, the debossing and aperturing means 543 inoludes a rota~ably mounted cylinder 555 for debossiny and selectively aperturing plastic films coming in contact thexewith, said cylinder having closed ends 580, a nonrokating triplex vacuum manifold assembly 556 and hot air jet means 559.
The triplex vacuum manifold assembly 556 comprises thxee manifolds designated 561, 562, and 563. Also shown in ~igure 14 is a freely rotatable lead-on idler roll 565, a power rotated lead-off/chill roll 566, and a soft-face (eOg~ low density neoprene) roll 5~7 which is driven with the chill roll.
Brie1y,';by providing means (not shown3 for independ~
ently controlling the level of vacuum in the three vacuum manifolds, a thermoplastic ribbon of film running cixcumferentially about a portion of the debossing-aperturing cylinder 555 i5 sequentially subjected to a first level of vacuum ~y manifold 561~
a second level of vaGuum by manifold 562, and a third level of vacuum by manifold 563. As will be described more fully hereinafter~ the vacuum applied to the film by manifold 561 enables maintaining upstream tension in the film, vacuum applied by manifold 562 enables debossing and selectively aperturing the film when hot air is directed radially inwardly ayainst the film, and vacuum applied by mani~old 563 enables cooling the ~ilm to below its softening temperature and enables establishing downstream tension therein. If desired, the film-contacting surface of the debossing-aperturing cylinder 555 may be prehea~ed prior to reaching vacuum manifold 562 by means well known in the art (and ~here-fore not shown) to facilitate better conformance of plastic films comprised of flow-resistant polymers during the debossing and selective aperturing operation.
The nip 570 intermediate chill roll 566 and the soft-face roll 5~7 is only nominally loaded because high pressure would iron-out the three-dimensional deboss-ments which are formed in the film in the aforemen-tioned manner. However, even nominal pressure in nip : SiO helps the vacuum applied by manifold 563 to isolate downstream tension (i~e., roll winding tension~
from the debossing-aperturing portion of the deboss-ing-aperturing cylinder 555, and enables the nip 570 to peel the debossed and selectively apertured film ~om the debossing-aperturing cylinder 555. Moreover, while vacuum drawn ambient air passing through the apertured portions 591 of the film into manifold 563 will no~mally aid in cooling the film to below its softening temperature, the passage of coolant through the chill roll 566 as indicated by arrows 573, 574 in Figure 14 will enable cooling of tne non-apertured portions 590 of the film 550~

To summarize, the first vacuum manifold 561, and the third vacuum manifold 563 located within the debossing~aperturing cylinder 555 enable ma~ntaining substantially constant upstream and downstream tension respectively in a running ribbon of ~ilm while the intermediate portion of the film adjacent the second vacuum manifold 562 within ~he debossin~-aperturing cylinder 555 is subjected to tension vitiating heat and vacuum to effect debossing and selective O aperturing of the film~
Referring again to Figure 14, the constant tension film supply means 541 and the cons~ant tension ~ilm forwarding and winding means S45 may~ if desired, t be substantially identical to and func~ion substan- ,~
S tially identically to ~he ~orresponding portions of the apparatus shown and described in UOS. Patent No.
3,674,221 issued to Riemersma on July 4t 1972. The debossing and selective aperturing means 543 comprises the rotatably mounted dekossing-aperturing cylinder 0 555, means (not shown) for ro~ating ~he cylinder 555 at a controlled peripheral velocity, the non-rotating .
triplex vacuum manifold assembly 556 inside the debossing-aperturillg cylinder 555, means (not shown) for applying controlled levels of vacuum inside the three vacuum manifolds 561, 562 and 563 comprising the triplex manifold assembly 556, and hot air jet means 559.

-~2 The debossing-selective aperturing cylinder 555 may be constxucted by generally follow-ing the teachings of the aforemen~ioned commonly assigned patent of Lucas et al., b~lt substituting a tubular laminate ~orming structure 460 of the type generally shown in Figure 11 for the perfora-ted tubulax forming surface disclosed therein. Ends 580 are secuxed in sealed r*lation to ~he lateral edges of the forming structure and the entire cylinder 555 is supported by means of a shaft 463 pass.ing through its center and secuxed to ends 580.
While particular embodiments of the present invention have been illustrated and described, it will be obvious to ~hose skilled in the art that various changes and modifications can be made without depart-ing from the spirit and scope of the invention, and it is intended to covex iII the appended claims all such modifications that are within the scope of this invention.

Claims (9)

Claims:

1. A continuous method of forming a plastic web exhibiting a substantially continuous three-dimensional pattern of debossments, a predetermined portion of said debossments being apertured at preselected points along the surface of said plastic web, said method comprising the steps of:
(a) continuously bringing said plastic web in contacting relation with a tubular-shaped laminate forming structure exhibiting a substantially continuous first pattern of apertures corresponding to said debossments and extending from the outermost to the innermost surface of said tubular-shaped structure, those apertures corresponding to the non-apertured debossments in said web having a perforate support member exhibiting a second pattern of aper-tures smaller in size than the apertures in said first pattern located interiorly of the outermost surface of said laminate structure;
(b) heating the portion of said web in contact with said forming structure above its softening temperature;
(c) applying a fluid pressure differential to said heated plastic web while said web is in contact with said forming structure to deboss said web in the image of said laminate forming struc-ture where said perforate support member contacts said web and to deboss and aperture said web in those portions of said forming structure where said perforate support member does not contact said web;
(d) cooling said debossed and selectively apertured web below its softening temperature; and (e) removing said debossed and selectively apertured web from said forming structure.

2. The method of Claim 1, wherein said tubular-shaped perforate laminate film forming struc-ture is preheated prior to bringing said plastic web into contacting relation therewith to facilitate better overall conformance of said web to said forming structure.

3. The method of Claim 1, wherein said fluid pressure differential applied to said web com-prises suction applied to the interior of said tubular-shaped forming structure.

4. The method of Claim 1, wherein said web is heated by directing a curtain of hot air against said plastic web while said web is in contact with said forming structure.

5. A continuous method of forming a plas-tic web exhibiting a substantially continuous three-dimensional pattern of debossments, a predetermined portion of said debossments being apertured at pre-selected points along the surface of said plastic web, said method comprising the steps of:
(a) continuously extruding a melt of plastic resin onto the periphery of a tubular-shaped laminate forming structure exhibiting a substantially continuous first pattern of apertures corresponding to said debossments and extending from the outermost to the innermost of said tubular-shaped structure, those apertures corres-ponding to the non-apertured deboss-ments in said web having a perforate support member exhibiting a second pattern of apertures smaller in size than the apertures in said first pattern located interiorly of the outermost surface of said laminate structure;
(b) maintaining the portion of said plastic melt in contact with said forming structure above its softening tempera-ture;
(c) applying a fluid pressure differential to said heated plastic melt while said web is in contact with said forming structure to deboss said melt in the image of said laminate forming struc-ture in those portions of said struc-ture where said perforate support member contacts said melt and to deboss and aperture said melt in those portions of said forming structure where said perforate support member does not contact said melt;
(d) cooling said debossed and selectively apertured melt below its softening temperature to form a web; and (e) removing said debossed and selectively apertured web from said forming struc-ture.

6. The method of Claim 5, wherein said tubular-shaped perforate laminate film forming struc-ture is preheated prior to bringing said plastic melt into contacting relation therewith to facilitate better overall conformance of said web to said forming structure.

7. The method of Claim 5, wherein said fluid pressure differential applied to said melt comprises suction applied to the interior of said tubular-shaped forming structure.

8. The method of Claim 5, wherein said melt is maintained above its softening temperature by directing a curtain of hot air against said plastic melt while said melt is in contact with said forming structure.

9. A plastic web exhibiting a substan-tially continuous three-dimensional pattern of debossments, a predetermined portion of said debossments being apertured at preselected points along the surface of said plastic web, said web being formed by:
(a) bringing the plastic material comprising said web in contacting relation with a forming structure exhibiting a substantially continuous first pattern of apertures correspond-ing to said debossments and extending from the web contacting to the non-web contacting surface of said forming structure, those apertures correspond-ing to the non-apertured debossments in said web having a perforate support member exhibiting a second pattern of apertures smaller in size than the apertures in said first pattern located intermediate the web contacting and the non-web contacting surfaces of said forming structure;

(b) applying a fluid pressure differential to said heated plastic material while said plastic material is above its softening temperature and in contact with said forming structure to deboss said material in the image of said forming structure in those portions of said structure where said perforate support member contacts said web and to deboss and aperture said material in those portions of said forming structure where said perforate support member does not contact said web;
(c) cooling said debossed and selectively apertured material below its softening temperature to form said web; and (d) removing said debossed and selectively apertured web from said forming structure.