CA2201495A1 - Flexible and stretchable absorbent articles and their fixation to undergarments - Google Patents

Abstract

The present invention relates to absorbent articles (10) such as sanitary napkins, panty liners, and incontinence pads which are adhered to an undergarment during use. More particularly the present invention relates to articles (10) which are stretchable in one or both directions, and which have a flexibility in a longitudinal direction which provides improved comfort to the wearer of the article (10).

Description

WO96/10974 ~ 2 0 i 4 ~ 5 PCT/US95/12557 . 1 Flesible And Stretcbable ~ e.-l Articles And Their Fisation To Undergarments Field of the invention The present invention relates to aL~u-L~,--l articles such as sanitary napkins, p~lylillcl~ and n.,l;~ . e pads which are adhered to an u~d~ lclll during use. More particularly the present invention relates to articles which are ~11, ' ' '- in one or both directions and which have a flexibility in a 1O~ direction which provides illlp-uvcd comfort to the wearer of the article.

Ba~,h~-ulll.d of the invention Absorbent articles such as sanitary napkins, p~ yli~ , and i .~c,~ e pads are typically worn in the crotch region of an uudcl~ul--c-ll and attached to the undcl~;alll.~,.~l by a so called panty-f~ctPning-adhesive In order to be coll~l b'e to the wearer these products need to be flexible. It is believed that the more flexible an absu.l~.lt product is the less will it be --~ ' 'e to the wearer.
Hence this provides comfort by more closely rr~ g the situation when no such aL so-l,c--l product is worn.

Flexibility can casily be achieved by reducing the amount of material in an ,~ product or ICpLl~ g ~ 7h~1-,,.L~ c4~ by more flexible ones. However it has long been rcC~J~;..;C~l that extreme flexibility can reduce the al~ull~ p- r5,. l~ e of these articles, for example by an i.~..lT;.: - ~ amount of ~c,lL.~ material or by l,~ g or dcl~iryillg of the aL~sulL,_nl material during use. Also a too flexible product may be difficult to handle for the wearer when ~ "~ it to the u..dc.~ t.

The problem of too much flexibility in a product due to a low amount of infll ' " material has been ad&c~scd for example in U.S. 4,217,901 where particularly the stiffness of an aLsc.-Lcl-l product is required in order to provide ~l ;~r~ l(.,y product p~ r....--~- e This prior art lcrcl~,~lcc accepts the comfort; .-I.lir~l ;O~c caused by its stiffness rc luln, Il~,nl.

It now has been found that the comfort of aLsulL~..l products can be d~ctir~lly i~ luvcd when providing a high flexibility in l~..g;l~ l direction, or low stiffness in cn ~ l;ol~ with a palliculdl panty-r;~ ;l g-adhesive cnnfi~ tinn so as to m~int~in the product flat relative to the u--~lc-~ --l of the wearer. The flexibility then becomes limitcd only by material l'C lUil~--lCllki (e.g. to provide 5~ffini~nt aL.~u.bc-ll p~. r.~....~... c) and by handling lC~llill,,.1.~,.11:~ of the aLsu-Lh,n product.

WO 96/10974 ,. I s ' PCTtUS95112557 f ~ ~ 2 ~ ~ 4 9 5 It is therefore an objective of the present invention to provide sanitary napkins with an hll~.uv~d flexibility without the previously experienced ~ v~achs. In particular a high degree of flexibility in t the absence of bunching problems without major handling ~iffi~nlti~.c is achieved by the present inventlon.

These and other objectives of the present invention will be more readily apparent when cul~i.lelcd in ,t;r~ nce to the following de~-;fi~lioll.

Summarv of the invention The present invention provides an al~ull.~ product such as a sanitary napkin, an i". u..~ .re pad and particularly a panty liner for use in an ulldel~ . The al)soll,.,.,l product has a garment facing surface which c~ s an adhesive to adhere the product to the Ull~l~ . Theproduct may optionally ~,olll~JIi~ plot.,~livt side-flaps which during use are folded around the side edges in the crotch region of the Illld~ so as to improve soiling plut~lion for the und~ ,nl. The al~ product also co ~ f C the other typical ~ of such products namely an al~u,l~n~ core and a liquid pervious wearer facing surface which is pn f~,.~ly provided by a liquid pervious topsheet. It is also typical that the abs(.llJ~ product co...l.. ;~rC a liquid illl~lviuu~ b.,~ L~1.f~ which usually provides the garment facing surface of the al)sull~.ll product.
If topsheet and bA~ L ~l~e~ are present the d,~ol~.ll core is enclosed by them on the wearer and on the garment side lti~Jc i~,~,ly.

The adhesive can cover the whole, part or several distinct parts of the garment facing surface. The adhesive can be provided covering the full sulface area or it can be in a fi1.. ~ Y fashion which is random or in a defined design. The total of all adhesive on the garment facing surface of the ~hso~ product defines the actual adhesive surface. In addition a IL~o~lical ~hf ci~n surface is given by the ~.iyhc.y of an endless line which is the shortest C,ll~,-i} ,Ihlg line of the adhesive without ~ - ~r -1; g beyond the peli~,h~,-y of the garment facing s~face itself.

As a .. ;.~;.. half of the garment facing slllface is provided with adhesive to attach the product to the ulldel~;allll~,nl. The al~sullclll product acculdillg to the present hl~,.l ion has a surface ratio of t theoretical ~flhf~cion sulface to the garment facing s~face in a range of 0.6 to 1, preferably 0.85 to 1 for products without the pl~ side flaps and in a range of 0.5 to 1, ~lc;r~,.d~ly from 0.7 to 0.9 for products with plu~;liv~ side flaps. In a l~lGr~ d l ....l ~l; ...~..l the theoretical ~1hf cif~n sulface is ~ lly c~ lt .. ~;ve to the actual surface covered by the adhesive.

WO96/10974 ~ 2 0 1 4 q 5 PCTIUS95/12557 . 3 In order to realise the benefits of the present invention the abso,l,cllt product as a whole needs to provide exceptional flexibility. The flexibility is ~--ea~u.cd by the modified ASTM method D1388 as des~,-ibed herein below in lou~ direction. The expression "flexibility" is also referred to as "drapability" due to the particular method. It should be l~nr~er.ctnod that stiffness is c~ lc~ istic of the opposite behaviour of a material. The flexibility should be in the range of 1300 to 3500, u,crc,al,ly from 1300 to 3000, most prcrc~ly 2000 to 2700, mg x cm.

These flexibility values in co"ll il.dLion with the surface ratio in~ir~tpd above provide ~ ~elltio wearer comfort without soiling and/or al)sc"l,cnl pe~ru~ cc plubl^-nc due to l, --. -l~i ~g or dPncifir~tion of the abso~l ~,.,1 material and still allows the wearer to attach the product to the uldcl~lllcnl without undue effort. According to the present invention flexibility is l~c~ulcd in longitl--iin~l direction because this is the value more readily ~ ,.I.Ir In p . '- the L~ v~ e flexibility also could be used, possibly at different values. Due to the small eytpncion of products in the L~ v~ c direction it is usually not possible to properly measure flexibility in this direction.

The thirlrnP.cc of a ~ . cd ~ .. l ~l i .. ,~ of the present invention especially for pa~tylill~l~ is less than 3 mm and even more p~crcl~Lly in the range of 0.5 to 1.5 mm acc~"~li.,g to the thir~nPcc lll~,d~ method (~fC~ ,d herein below.

The ,o...l.;"~lion of a~lU~ t~, panty-f~ctPning adhesive coverage and flexibility is particularly useful in the context of ~ !.e al,soll Clll products. Absorbent products being ~Li~ ' a~l~ in one direction and more so dbSCill~nl products being ~L~ ' ' '- in two (or all) directions are inherently flexible. Stretrh~hility in itself already provides an hlllJluv~ ll for comfort such that the al,su.l~.~l products c,,...l.;..iug ~Licl~ h~l.;lity with the present il,~_nLiion are ~dlLicllldlly dPcir~h!P

Pd Lii~ ldlly useful are ~Li~ h~' le al,~o-l~.-t products having the stretch ~h,..,.. ~ ilics ~1PC~" ih~fd on US ~rrlir~tifm number 08/192,240 filed February 4, 1994 and i...l; ~t~ d in the Table of Figure 7 and the ~ _ dPcrrirtion of that arplir~tion For products which are :,L,. ' ~ ~- the limit:ltitmc on flexibility are less strict. In palLi~,uldl according to.the present invention ~LIcl~hab'- ~ull~.lt products can have a flexibility of 5000 mg x cm to 1300 mg x cm with an actual adhesive surface of at least 20 % of the garment facing surface, for p~ntilin~rc without ~.ulccLivc side flaps the adhesive to attach the r~ntilin.or to the Ill.d~,E;a lll~,.lt may be provided as an endless strip closely following the pCliph~,~y of the p~ntiliner and leaving a s-l..,~ l portion of the r~ntilin~?r inside the endless strip free of adhesive.

Brief i~c... il.ti-... of the dldWill~

WO 96/10974 ~ PCTIUS95/12557 220 1 495 ~

Figure I shows a plan view of the garment facing surface of a p~ullylil~l without protective side flaps according to the present invention.

Figure 2 shows the garment facing surface of a sanitary napkin having ~,ulcclivc side flaps acl o,di.,g to an alternative r-nnho~imr-nt of the present invention. '~

Detailed description of the present invention The present invention will be desc,il,ed by ~crt~cllce to pdlllylincl~. It is however equally well app1i~h1~- to sanitary napkins or adult il~ro..li"~.1ce products which are worn in an undcl~dllllc and are joint to the undel~ ". .~L during wearing of the alJso~l~..t product.

Absorbent products according to the present illvclllion comprise typically three main COIIIIJdllCIII~. a liquid pervious topsheet a liquid impervious l.a L ~ and an dlJSOI~ core. The db~ulbclll core is enclosed by the b .,- L ~ and the topsheet and the product is worn such that the exposed surface of the topsheet faces the wearer of the abso,l~"l product while the exposed surface of the 1,~ L ~l~f .
faces the l.ndcrgdl lll. .ll to which the product is joint by a panty-f~ning ,~ 1 means.
Typically this is an adhesive but could also be a .. f l~nif~11y ~

The present invention is conc~ . ~-d with the flexibility of the product. The degree of flexibility is dcLtllllil.cd by the selection of the m~tf-ri~1c for the co...~ of the product as mf ntif nf d above and their ,c~l e- liv~i quantity. It will be apparent to those skilled in the art that in order to achieve the flexibility acco,di"g to the present hl~. the selection of kind and quantity of raw materials has to be balanced with other desired ~ l;- c of the abs("l~.,l product sueh as for example al~so,lA .Il capaeity al~so,y~ion speed and surfaee dryness on the outside of the topsheet during use.

Therefore the following d~- - ;y~ of typieal -1c of the main ~u-. ln- - ..1~ of the alJsc ll~lll product will allow to provide an almost infinite number of product variants inside and outside the flexibility limit^-ionc acco, lh.g to the present invention. Whether or not an al~u,l~.,l produet meets the I~Uil~,.l..,.lI~ of flexibility of the present i"~ iùn can then be analysed by simple III~UICII.~ acco,ding to the method d~-c- - ;1 ed below.

The ab~u,l~.l~ artieles according to a ~crt~lcd c 11~1;~ 1 of the present il~vc"lioll are elastically slld~'~l le The term 'elastically ~l,, ' ' I ' as used herein means that when the stretching forces are removed the article will tend to return toward its .. ~ or UllallCl~ Lcd (or 'original' nc) It need not return all the way to its u~ t~ hed l1;.. - :o,-c however. If the abs("l~"t 2 2 0 1 4 9 S PCTIUS95Jl2557 s article is elastically stretchable it may be stretchable in one or two directions (which are not-parallel) within the plane of the product i.e. parallel to the garment facing surface.
c Materials for elastically ~ Gl~_hable articles ean be elastically ~lrelchable per se or be treated so as to provide elastie ~ l .lility. In partieular elastie b~.`L ~ material, elastie topsheet material, fil~ y materials co~ i with elastie strands, threads or webs as well as shirring, pleating or ring rolling of the materials may be employed in this eontext. Suitable material and methods are known in the art and e.g. ~icrlosed in detail in US ~ppli~ti-~n 08/192240 of Februaly 4, 1994 sperifi~lly referred to in order to facilitate selection of materials if ..L-~ h ~ 'e absc -l,G.-l artieles aceording to the present invention are made.

In the following, non-lirniting c .l~ of the main elements of the abSOl'UGlll produet are cle~-,- ;l.ed whieh can be .. . IuyGd in elastieally ~ or non-..L,, ~ designs.

Absorbent eore The ab~ullJ~ eore typieally ineludes the following cu...~ (a) optionally a primary fluid distribution layer; (b) optionally, but IJlGrGldblv, a SGL-U--dCUV fluid li~LIibulil)n Iayer; (e) a fluid storage layer; (d) optionally a fibrous ("dusting") layer underlying the storage layer; and (e) other optional 5X,~ n~

a. Primarv Fluid Distribution Laver One optional co...~ of the al,so.~. eores aecu.ding to the present i.l~,.lLion is the primary fluid .l ;~ l ;Ol~ layer. This primary ~;~1. il .--l ;.... Iayer typieally ....~ c the topsheet and is in fluid cc,---~ n IL~,~GWilll. The topsheet transfers the aequired Ill~,.~.ll~l fluid to this primary ~ictri~ntifr~ layer for ultimate li~ ion to the storage layer. This transfer of fluid through the primary ~li~l . il .. .l ;..ll layer oeeurs not only in the ~ L .-~ c~, but also along the length and width dilt.;Lions of the a'L soll~nl produet.

b OPtional Seco.l.la.v FluidD;~l.;l...l;c.~ Laver Also optional but a ".Grt.ltd ~x.~ u..~ of the ab~ullJGlll eores ac.,oldillg to t'ne present invention is a secon~l~y fluid ~ 1. ;l .. .1 ;Ol~ layer. This se~,ûn~ku v distribution layer typieally . .. ,ti~ c the primary distribution layer and is in fluid c(,.------ -~ h.,.GWilh. The purpose of this second~y di~llibuliùn layer is to readily acquire l--~,~.L,ual fluid from the primary ~lictriblltion layer and WO 96tlO974 ~ 2 2 0 1 4 9 5 PCT/US95/12557 transfer it rapidly to the underlying storage layer. This helps the fluid capacity of the underlying storage layer to be fully utilized.

c. Fluid Stora~e Laver pocitinnpd in fluid co.,.. i~ ion with, and typically uu~dell~ g the primary or secon~Luy ~lictrihution layers, is a fluid storage layer .,u...~ ;..g certain al,sull,r,lll gelling m~trri~lc andtor other al)sc,ll,~,.ll materials, which can form the carrier matrix for the al~sc,l~nl gelling m, t~ri~lc Absorbent gelling materials are usually referred to as "hydrogels," "~ hsn.l~.ll" "hydrocolloid"
materials. Absorbent gelling l..~lt~.ials are those m~tPri~lc that, upon contact with aqueous fluids, especially aqueous body fluids, imbibes such fluids and thus form L.~d~U~IS. These ab~ul~
gelling materials are typically capable of absorbing large ~ i. c of aqueous body fluids, and are further capable of retaining such absorbed fluids under Illn(lrl~ pl~_~aul~a. These ~L~oll,~,.ll gelling materials are typically in the form of discrete, nc,l,fll,luua partieles.

The fluid storage layer ean co...~ e solely al~soll,.,.ll gelling In~trri~lC or these al~ull,.,.ll gelling materials ean be ~ aed hn n~ ull~l~ or non-h.,...o6..-. u~ in a suitable carrier or it can COIllAJliae solely an absc,lb~lll carrier material. Suitable carriers include cellulose fibers, in the form of fluff, tissues or paper such as is conventionally utilized in al,scHI~l.l cores. Modified cellulose fibers such as the stiffened cellulose fibers ean also be used. Synthetic fibers can also be used and include those made of cellulose acetate, pol~vil.~l fluoride, polyvinylidene chloride, acrylics (such as Orlon), polyvinyl aeetate, non-soluble polyvinyl alcohol, polyt;ll.ylr.,e, polypropylene, polyamides (such as nylon), pOl.~ a, A ' fibers, trif c. ~l~" ' fibers, mixtures thereof and the like. Preferred synthetic fibers have a denier of from about 3 denier per filament to about 25 denier per fil~ml-nt. more ~,~,f~,.~l~ from about 5 denier per filament to about l6 denier per fil-m~nt Also p.t;r~,~ly, the fiber surfaces are hydrophilic or are treated to be hydrophilic. The storage layer ean also include filler m^~ lc such as Perlite, ~ U"~A~ earth, Ve~mi.~ e, etc., that lower rewet ~,u~' ~ .

If .~ )ru~t'd non-h--..-n6r~-~uu~ly in a carrier, the storage layer can be loeally hn~..n~r~ u..c i.e.
have a ~iictrihution gradient in one or several cli,c~ ions within the ~l;---~--~;ol~c of the storage layer.
Non-hn...o~ o..c ~ictrihntinn can also refer to l,....;..~ c of carriers en-locing al~sc"l~,lL gelling materials partially or fully.

Pl~ al~ly, the storage layer colll~liaes from about 15 to 100% al)sc"l~nl gelling materials and from 0 to about 85% carrier. Preferably, the storage layer cn~ Pc from about 30 to 100 %, most WO96/10974 2~0 1 4S~ PCT/US95112557 preferably from about 60 to 100% abso~ nl gelling m~tt~riAIc and from 0 to about 70 %, most preferably from 0 to about 40 %, carrier.

Suitable ab.,o,l)~llt gelling materials for use herein will most often comprise a S~lb,~ AIIY water-incoh ' 1-, slightly CI~J~ partially neutralized, polymeric gelling material. This material forms a hydrogel upon contact with water. Such polymer mzttPriAIc can be preparcd from polyll~ dlJle, ullsalulal~d, acid-co..lA;"i"g ...~ Suitable u~AII~trd acidic ..O~ for use in ~ Jauillg the polymeric al~scll,~llt gelling material used in this invention include those listed in U.S. Patent 4,654,039 and reissued as RE 32,649. PlcÇ~ d .... ~ ..s include acrylic acid, ..~,II.aclylic acid, and 2-acrylamido-2-methyl propane sulfonic acid. Aerylic aeid itself is espeeially ,f~ dfor~ pA.~dl;.)l- ofthepolylll~ilicgellingmaterial. Thepolymeriec~ l .,1 formedfrom the ~ . . .~1,. . i~lr~, aeid~o. .1 A; ~ g ~.-nl~o~ can be grafted onto other types of polymer moieties such as stareh or c~ lost? Polya~;lyldlL~ grafted stareh m tteriztlc of this type are especially ,f;,lled. Plef~ d polymerie ab~.,ull~.ll gelling mzttt~ri-tlc that ean be prepared from eoll~,.,lltio types of ---~ include Lydluly~d acrylonitrile grafted starch, polyawylalu grafted starch, pOlya.,-lyLt~,s, maleic anhydride-based cu~lyll.~,.., and co. . .1.; .~,.1 ;hl~C thereof. F~?Ci~lly plt;rt;ll~d are the polyd~,lylal~s and polyd~,lyl.~t~, grafted starch.

While these absoll,~ gelling m,ttL?ri~lc are typically in particle form, it is also C~ t~ ~r' -trd that the al,~ull~lll gelling material can be in the forrn of Illa.,lu~.,llu.:~ u~s such as fibers, sheets or strips.
These Illa.,lu.,l- u.iluu~,., are typically prepared by forming the pa~ lale absoll~.ll gelling material into an ag6l~Ejal~:, treating the ag6l~0~t~d material with a suitable .,1~ ' g agent, ~~ ~ liug the treated a66l~,6ale to densify it and form a coherent mass, and then curing the co...l~ d a66u~ 0 to cause the ~jl"~l;"~ g agent to react with the IJauli~ ldle dJ.7cl1J~,Ill gelling material to form a co ~1~~; Ir, porous dl~.7ul~llt Illa~,lu.~Ll u~,luut;. Such porous, al)scul~..l lua~,ru.,ll u.;luut;s are ~licrlnc~1 for , 11,?, in U.S. Patent 5,102,597.

d. Optional Fibrous ("Dustin~") Laver An optional '`J"'l ùl.~ ~1 for i".-l.. i~.. in the ab.,ull~l-l cores according to the present invention is a fibrous layer adjacent to, and typically und~,llyhlg the storage layer. This uu~dcll~yhlg fibrous layer is typically referred to as a "dusting" layer since it provides a substrate on which to deposit al,sull~
gelling material in the storage layer during ,.. ,.. r;.. ~ of the ab.,c ll~l-t core. indeed, in those c where the al)sol~ gelling material is in the form of ~ a~ lu.,llu-,luucs such as fibers, sheets or strips, this fibrous "dusting" layer need not be inrl~ c~l However, because this "dusting"
layer provides some ~ tion~l fluid-h~n~iling c~p~hilitirs such as rapid wicking of fluid along the WO 96/10974 ~ PCT/US95J12S57 220~49~ --length of the pad, its inclusion is typically preferred in absu.b~ cores according to the present invention.

e. Other OPtional Co-"~one..l~

The al)so-l,~nl cores acco-ding to the present invention can include other optional CO~ U~
normally present in ab~u-be--l webs. For example, a ~ rul~_hlg scrim can be po~i l inl~pd within the respective layers~ or between the ~ e~;liv~ layers, of the abstJ,l~..l cores. Such ~ ruluing scrims should be of such confi~-r~tic n as to not form i..t~ r;. i~1 barriers to fluid transfer, especially if positiont d between the I ~ Liv~ layers ûf the al,~v~ core. Given the structural integrity that usllally occurs as a result of thermal bonding"t;il~rul~;illg scrims are usually not required for the ab~ull,~ u~ s acctjldillg to the present h~v~lllion.

Another CO~ JUn~ which can be included in the al,so-l~..l core accoldil.g to the invention and p.~rt.~l~ is provided close to or as part of the primary or sccû..~y fluid (lictrib~lfion layer are odor control agents. Typically active carbon coated with or in addition to other odor control agents, in particular suitable zeolite or clay ~ lr~;~lc, are optionally L~.,tJl~ul..t~,d in the al-so.l~.l core.
These co...l~l~ can be in~ul~l..t~d in any desired form but often are included as discrete, non-fibrous particles.

Topsheet The topsheet is ~.tJ~-pli~311l, soft feeling, and non-irritating to the wearer's skin. As in~ir~ftd above the topsheet also can be elastically ~ '.L'~ ~e in one or two dil~ iùlls. Further, the topsheet is fluid pelvious p~ liug fluids (e.g., menses and/or urine) to readily pf ... l,;.l~ through its ~ l "~ A
suitable topsheet can be .II~ r~ d from a wide range of m~tt~ri~lc such as woven and no......
m~trri~lg, yolylll~ilic m~tPri~lc such as a~.lulcid formed Ih.. n~ lir films, a,~.lul~d plastic films, and L~dlurolll~ th~- ~..npl .~lir films; porous foams; refic~ tPd foams; retirnl l.. n~ l jr films; and ~ llllu~ ic scrims. Suitable woven and nvll~ov~ .. ;.t~ k can be ~~ Pd of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polymeric fibers such as pol~ ,l.,., poly~.u~l~,..c, or pol~ c fibers) or from a cu..ll,h~liol of natural and synthetic fibers.

~ f,.l~d I for use in the present are selected from high loft nol.~.Jvtin t~ hPrl~ and aperture formed film lù~lle~. Apertured formed films are especially p.tir~ d for the topsheet because they are pen~ious to body exudates and yet non-abso~l~..l and have a reduced l~nden~ to allow fluids to pass back through and rewet the wearer's skin. Thus, the surface of the formed film W096/10974 ' '~ 22U ~ ~9~ PCT/U595112557 that is in contact with the body remains dry, thereby reducing body soiling and creating a more culllrollhl)le feel for the wearer. Suitable forrned films are desL~ ed in U.S. Patent 3,929,135; U.S.
Patent 4,324,246; U.S. Patent 4,342,314; U.S. Patent 4,463,045; and U.S. 5,006,394. Particularly pl~r~ d micludpel u~d formed film ~o~ are licr~ncPd in U.S. patent 4,609,518 and U.S.
patent 4,629,643. The ~Ic;Ç~ d topsheet for the present hlv~ ioll is the formed film IPS~ ;l.Pd in one or more of the above patents and ~ L~ ted on sanitary napkins by The Procter & Gamble Company of CinrinnAti Ohio as "DRI-WEAVE."

Topsheets having not a homcgc.leous li~llibulion of liquid passage ways but only a portion of the topsheet cu...~ g liquid passage ways are also CO~IL~ d by the present h~v~ lion. Typically such IO~1.P~I~ would have the liquid passage ways oriented such that they result in a centrally pc"~.~,al~le and perirh~r~lly i"",~;, ' '^ topsheet for liquids.

The body surface of the formed film topsheet can be hydrophilic so as to help liquid to transfer through the topsheet faster than if the body surface was not hydrophilic. In a p,~,f .l~d Pmho iim~ont 5llrf~rtmt is hrco,~u,~ed into the polymeric m~tl~ri~l.C of the formed film topsheet such as is dPc~ P~ in U.S. Patent ~pplirAtiQn Serial No. 07/794,745, filed on Nuv.,l.~el 19, 1991.
Alt~l,.d~iv~,ly, the body surface of the topsheet can be made hydrophilic by treating it with a ~" r~ such as is des~--il,cd in the above l~rt:l~.rct;d U.S. 4,950,254.

RA. L ~1~eC I

The b A- L~1,P~ prevents the exudates absorbed and C(J~ d in the absu~bcilll core from wetting articles that contact the sanitary napkin such as pants, pajamas and ul.d~i,g,.",. .1~ The b~l~ L~
is h~.viu~ to liquids (e.g., menses and/or urine) and is ~ f~,.~ly l..~ ...cd from a thin plastic film, Alth~l.gh other flexible liquid impervious ,. ~,~lr~ i~l.c can also be used. The ~ L ~1 ~P~I
needs to be c~....l.liAI~1 and will readily conform to the general shape and contours of the human body. The l ~ L ~ also can have ~ 1 ;. c allowing it to elastically stretch in one or two ,.,tio,ls.

The b~- L~ can C~ e a woven or r.u..wuv~ material, polymeric films such as th~.l..u~ tic films of polye~ c or pol~ u~ylene, or co~p~;lr. m~t~ri~lc such as a film-coated no"wuv~
material. Preferably, the b i. L ~ is a polyt;tl.ylene film having a t~ i L ~ of from about 0.012 mm to about 0.051 mm.

E~C.~IJI~Y poly~tl.yl~.le films are .~ ~ by Clopay CullJuldliOl of Ci,.~;",.~1; Ohio, under the ~l cign~tinn P18-0401 and by Ethyl Corporation. Visqueen Division, of Terre Haute, Indiana, WO 96/10974 2 2 0 1 ~ ~ 5 PCTIIJS95112557 under the ~l(?ci~n~tion XP-39385. The b~rkchret is pl~r~ldbly ~ lbos~ed and/or maKe finished to provide a more clothlike appP~r~nre Further. the b~ l.e~ can permit vapors to escape from the ab~ull,~ structure (i.e., be breathable) while still preventing exudates from passing through the b~kch~et, The pantv-f~ctenin~-adhesive The l; ~- L ~ typically forms the garment facing surface on which the panty f~ct~nin~ adhesive is placed.

According to the present invention it is hllpol~ll that the ratio of tl.eul~lical a~lh~sion surface to actual garment facing surface is within the range accc,ldillg to the claims of the present ill~ iUII.
The theoretical ~rlht~ci~m surface is defined by the surface area inside the shortest possible endless line encircling the panty-f~ct~?nin~ adhesive however without ~l t~l;".~ beyond the ~.il~h~ly of the garment facing surface.

In addition the actual adhesive surface needs to be at least 50 % of the garment facing surface or at least 20 % for ~ u ' le absol~ articles. If there is for example one lt~ a&esive area on the garment facing surface then the theoretical ,~lhpsion surface and the actual adhesive surface are id~nti~l this can be seen in Figure 1 where the adhesive 22 is h~ l by h~tchin~ The encircling line 26 results in a t1lwlc;lit dl ~tlh~ n surface 24 identical to the surface covered by the adhesive 22. For al~sc.lb,;lll products having IJlU~ side flaps Figure 2 shows that the three adhesive areas 22 are smaller in surface area than the LLeo1t_Li~l a~ht~ion surface 24 encircled by line 26. If the b~ L`h- ~,1 is elastically ~LI, ' ' 'o the adhesive surfaces are lll~.,l~l on the ~111 tLIt;L~,ll~ b... L ~ I prior to initial ~LIt;l ,l illg therwf.

Panty-f~ct~nin~-adhesives can ~ u~ any adhesive or glue used in the art for such purposes with pressurc-~".,iLiv, adh_i,ive~ being pl~ i. Suitable non: ' le adl..,i,iv,_~ are Century A-305-IV .~ r; ~ d by the Century Adhesives Corporation, Instant Lock 34-2823 m~n--f~ nred by the National Starch Company , 3 Sigma 3153 ,..~....r;.l l ..,~ by 3 Sigma, and Fuller H-2238ZP
fi l~..ed by the H.B. Fuller Co. Suitable a&esive fasteners are also d~s~ilil~d in U.S. Patent 4,917,697.

Suitable ,_Al,_.l~;ble adhesives for use as panty-r~ E adhesive include ,. ' " adhesives, per se, and t ' ' ~ adhesiv~ L ~h~l CO~ "~ C Any ~ ' ' - ad_esives known in the art can be used. Suitable ~ adhesivcJl,~ L ~l.,-,-l co...l.i",.~ c are for example non~ o adhesive used on an ~ ~ ~ - 1".. 1. ~h~l rnaterial such as 3 Sigma 2474 available from Anchor WO 96/10974 , ~ PCT/US95/12557 Continont~l Inc., 3 Sigma Division, of Covington~ Ohio; elastically ~Llt;~chalJlc adhesive films such as Findley adhesive 198-338, or an elastically stretchable adhesive film known as 3M XPO-0-014 available from the M;,~n~vl;. Mining and M~,..,r;~ i"E Company of St. Paul, Mi,,i~su~ or spray adhesives such as 3M adhesive 1442 on a lo~ modules elastic film. Other suitable panty-f~ctening adhesives are shown in PCT Tnt~orn~ti-m~l Patent Publication No. WO 92/04000; WO 93/01783 and WO 93/01785.

It should be llnflPrstnod that if it is desired to make the COIIIIH ~ l that forms the garment facing surface of the sanitary napkin (and any ov~.lyh~g Colllpo~ " le in the wearer's panties, the particular adhesive confi~r~tion that can be used depend on whether ~ or ~ ~-adhesives are used. The portion of the sanitary napkin on which, ' le adhesives are located will be ~t~,.lsilllc. Sanitary napkins co"l~;";"g i~ ,'- adhesives will typically only be capable of ~o~onci~)n between the in~ adhesive patches. Therefore, if i,-t;~ a&esives are used, they are pltrtldbly applied in illtL 1~1;111-1~l patterns such as for example i"lt,l---ltu-ll dots, ;llr..l strips, random or designed fil~ ,..y patterns to permit the sanitary napkin to extend. If, on the other hand, the a&esive is e~ the adhesive can be applied in ~u~ o~
or illlr.l..;ll~ patterns.

In addition, other types of r~lel,~,~ can be used instead of, or in addition to adhesives. These other types of r~t~ are arranged in patterns similar to those of the adhesive. Such r~l~ include, but are not limited to conventional VELCRO hook material or similar r-~lr,~

The p-ult.;Li~, side flaps can have optional fasteners thereon for ~ ition~l security. The optional p.ut~Li~_ side flap r;.~ can be any o the types of f~oning m~t~ri~l~ herein above. The L~lt"t;~ assist the prot~Liv~ side flaps in staying in position after they are wrapped around the edges of the crotch surface of the l"ult~Li~_ side flaps.

Prior to use of the alJsull~llL article the panty r;.~lr~ g adhesive is typically ~ from co l~ and from sticking to any surface where this is not desired by a l.,ul~.,Liv.~ cover means such as a silicone coated release paper, a plastic film or any other easily ~ vv. ' '- cover.
The protective cuvt;llll~ls can be provided as a single piece or in a multiude of pieces e.g. to cover the individual adhesive areas.

Flexibilitv or drapabilitv ~"ea~uie".~.-l The p~uc~l u~ for ".~uui~-g the flexibility/~r~p~hility of the ~s(.ll~.ll article is as follows:

WO 96/10974 , ~ PCTtUS95/12557 - ~ 2~0 1 495 REFERENCE ~_ ASTM Method D 1388-64: Standard Methods for Test for Stiffness of Fabrics (modified as riecf~riheti herein).

PRINCIPLE

This test is based on the cantilever beam p~ . 'e. The distance a strip of sample can be extended beyond a flat platform before it bends through a 41.5 angle is l.le~ul~d. The inter-action between sample weight and sample stiffness III~UI~d as the sample bends or drapes under its own weigth through the given angle under ~ifir~d test co~ ;o~ ~ is used to calculate the Flexibility/Drapability.

GENERAL COMMENTS

The flexibility test is only one way of .-~ i..g a sample's flexibility and is believed to be one of the co...~on~ ts which users of al,~u.l~.lt articles often refer to as softness. This --~u~ t method should be followed as closely as possible and schould not be confused with the multidirectional flexibility d~ s,,lil,ed in US 5,009,653. Even so testing of samples in only the longi~ in~l direction is ~ . . il.ed and r..,~,e~y for the present invention it is also possible for very wide or exceptionally flexible products to measure flexibility in the tl~L~el~i direction.

In general, a single sample strip should be tested only one time. The two sides of the sample should be tested on different sample strips. Likewise, sample strips for use in this test must be very carefully handled to prevent folds, wrinkles, bends, etc. This test is intended to be used on products before they have been folded or bent for pd 1- ~,j" by the ,..~.. r;.~ ". If the sample is placed by the """",r 1~.~, in a folded confi~ tion it should be gently unfolded for the test. If only folded products are available, the Flexibility/Drapability can be d~ by ~- ~c ~ g a sample taken from between the fold lines. The test should be.used on _ A ~ ' samples, i.e. with all layers having the sarne shape e ltn.l; ..~ to the c , ' : sample surface and fully glued together.
For each sample four different strips with topsheet up and four different strips with topsheet down should be ...~ultd. Samples should be ~ulcd in lol.~;l. J;.l~l direction.

To note for relative stiff ~oll~nt articles .~u~ even in lor~g;l~ l direction may not be ,; . ,~1 ,Ic due to the sample length being i .n~. . r~i : . ,I for bending through 41.5.

APPARATUS

22014~5 WO96/10974 ; ~ i f ~ 3 " PCT/US9S/12557 Cantilever Drape Stiffness-Tester Type SDL 003B SDL Tnt,~ tion~l Obtain forrn Carl von Gehlen/Germany (Tel.: 02168/2910; Fax 02168/24570) l-inch Wide Cutter Double edge cutter, 25.4 mm wide (1 inch) Col~ition~ Room A room cnn-lition~d to 21.7C - 23.9C, 50 /O+ 2 % Relative Humidity Talcum Powder Zerostat Anti-Static To ~li...;..,.l~ static charge on the drape Pistol (optinal) tester and/or tissue. Di~llibuled in the USA by Di~ l.cr, Inc., Columbia, MO 65201.
May be obtained from Morgan I~ u~ , Inc., P.O. Box 46442, 113 Circle Freeway Dr., Cinrinn~ti, OH 45246.
Morgan Catalog No. 70-35-00. Also available from record shops and rhnto~ .h:r supply stores. Use of this pistol is an approved way to remove static charges for this test. Never use fabric softener to remove static char~e from a drape test. Operate the Anti-Static Pistol according to the ...~.,..r~ S
instructions.

SAMPLE PREPARATION

The samples should be placed in an area of the room ~....il~ g ..~il.llllll recirculation of air and g y~ ihr~tinn with the humidity and t.,..~ luu~; ~.",-liliol~c 1. Cut 8 samples using a l-inch wide cutter. The sample strip has to be cut len~llwi~e from the center of the al~su.l~lll product to be ~ without crimp. Usual sample .l;.- .. ~i..,~c for Ill~l~.ll~,nls are 2.54 cm x 14.0 cm = 35.56 cm2. The samples may be shorter but must comrrice al)~u-klll material lluou~l~ûul~

f~ :

WO 96/10974 ; L~ 2 0 1 4 Y 5 PCT/US95/12557 2. Remove the release paper and weight the sample (mg). Round the weight to the nearest l mg.
r 3. Carefully powder the PFA with the .lli";"".~.~ amount of talcum sllffi~ien~ to avoid sticking. Blow out the l ..,.;..;l~g talcum from the sample.

4. Weight the sample strip with talcum (mg). Round the weight to the nearest l mg.

5. For each sample calculate the basis weight of the sample based on weight l~ n with and without talcum and the actual surface area of the sample.

6. Discard the sample if its weight hl~,~t d more than 2.0 mg/cm2 after adding the talcum.

INSTRUMENT OPERATION

Drape-tester should be placed on a bench directly in front of the operator. It is i,..l,u-~.l that the bench is l~,ldlivcil~ free of vibration, that there is no air flow during the l~ ,e.~l and that the bench is free of draft.
The operator may either sit or stand in front of the tester while it is being used. Then the operator has to chose his position so that looking in the mirror of the tester he sees the front ,t;rt;l~,..ce line covering the back ,Gr~,~nce line. If he sees only one line he has the right position for the ",e~u,~,...c.-l.

The tester shall:
1. Remove the sample slide bar from the sample slot on the top platform of the drape tester.
2. Place the sample trip on the sample slot so that one end of the strip is exactly even with the vertical edge of the tester. The strip should be placed as close as possible to the side rail of the sample slot but not touching it.

3. Place the sample slide bar on top of the sample strip so that its front edge is aligned with the edge of the sample strip in the tester and so that it touches the side rail. The sample slide bar must be carefully placed so that the sample is not wrinkled or moved forward.

4. Pulling from its free edge and using very light, gentle pressure, move the slide bar slowly and steadily forward with a speed of about l cm/s. As the slide bar moves forward, the sample should move at an equal slow rate. As the slide bar and the sample strip project over the edge of the tester, WO96/10974 ~ 2 2 0 1 4 9 5 PCT/US95/12557 .

the sample strip will begin to bend or drape duwl,~drd. Stop moving the slide bar the instant when the leading edge of the sample strip falls level with the 41.5 ~re~tn,_e lines.If the sample has a tendency to twist, take the ~rt~ -ce point at the center of its leading edge.
Samples which t vist more than ~5 cannot be --~asultd. Samples can only be ~e~ul~d if the sample length is at least 0.5 cm longer than the uvt;lLallg length. For non ..casu,~lc samples, the overhang length can be n.,~u~d only if a long enough strip can be obtained which is at least 0.5 cm longer than the overhang length.

5. Mark the overhang length on top of the sample (Overhang l.~n~h rlict~nre from the start point of l-~uv~ t until the point where the sample bends through 41.5).

6. Measure the overhang length in cm with a ruler. Read the overhang length to the nearest 1 mm.

CALCULATION

The equation used to express Flexibility/Drapability ac-,u,ding to the present i,-~cnlio-- is as follows:

G=WL3 Where G equals the Flexibility/Drapability, W is the sample basis weight inrhl~ling talcum in millig.;.. ~ , and L is the length of the u~. ' lg in cm. Results are A~.t~,d in milli~mc x cm or grams x cm.

Thickness l..ca~.rt..~

The ll.;.~L r ~ should always be --ca~ ,d at the thickest possible place, usually in the center of the ab~fJ.~..I article. For collv~ ,n.~c the l..w,~.,....,.l~ is CQ ~ h.. It~ on the absu-l~.-l article inclusive any p~ vt cover means present. The product should be lC~.~r 1;l ;O~f Y1 at 50 % humidity and 23 C for two hours within its usual package and be removed not more than five minutes prior to the The ll.;. L ~- `` is ~ d with a micrometer gauge having a range of 0 to 30 mm and capable of plus minus 0.5 mm tl-l ,f The gauge must not be spring loaded and should have a foot moving WO96/10974 ~ 2 0 1 4 9 5 PCT/USg5/12557 duwl~wa~ds under gravity. The mi~l)m~ter foot has a diameter of 40 mun and is loaded with a 80 gram weight. The ~lleasuu~,.llenl is taken between 5 and 10 seconds after the foot has been lowed to come into contact with the al)su.l,clll article. Measuu~ should be taken often enough to allow st~tic~ic~l analysis to determine average thirkn~c.c within a sigma of plus minus O. l mm. A detailed description of the thi~knPcc ll~a~u,~"l~;"l can also be found in US-Patent 5, 009,653.

Claims (8)

Claims - Flexible and Stretchable

1. A flexible and stretchable absorbent product for use in an undergarment, said product optionally comprising protective side flaps, said product comprising a garment facing surface, said garment facing surface comprising an adhesive to adhere said product to said undergarment, said adhesive having an actual adhesive surface and said adhesive defining a theoretical adhesion surface inside of an endless line which is the shortest encircling line of the adhesive without extending beyond the periphery of the garment facing surface said product being elastically stretchable at least in one direction parallel to said garment facing surface, preferably in two directions not parallel to each other but both parallel to said garment facing surface said product being characterised by the combination of -the surface ratio of said actual adhesive surface to said garment facing surface is at least 0.2;
-the surface of said theoretical adhesion surface to said garment facing surface is in the range of 0.6 to 1.0 for products without said protective side flaps, and in the range of 0.5 to 1.0 for products with said protective side flaps; and -said product has a flexibility of 1300 mg x cm to 5000 mg x cm measured according to modify ASTM D1388.

2. An absorbent product according to claim 1 wherein said flexibility is in the range of 2000 mg x cm to 3500 mg x cm.

3. An absorbent product according to claim 1 wherein said flexibility is in the range of 2000 mg x cm to 3000 mg x cm.

4. An absorbent product according to any of the preceding claims wherein said surface ratio of theoretical adhesion surface to said garment facing surface is in the range of 0.85 to 1.0 for products without said protective side flaps, andin the range of 0.7 to 0.9 for products with said productive side flaps.

5. An absorbent product according to any of the preceding claims wherein the maximum thickness of said product along an axis perpendicular to said garment facing surface is less than 3 mm, preferably in the range of 0.5 mm to 1.5 mm.

6. An absorbent product according to any of the preceding claims wherein said product has no protective side flaps and said surface ratio is 0.9 to 1Ø

7. An absorbent product according to claim 5 wherein said adhesive is provided as an endless strip following the periphery of the garment facing side of said product such that said surface ratio of said actual adhesive surface to said garment facing surface is from 0.2 to 0.5.

8. An absorbent product according to any of the preceding claims wherein said product is a panty liner.