CA1295103C - Production of non-woven fibrous articles - Google Patents
Production of non-woven fibrous articlesInfo
- Publication number
- CA1295103C CA1295103C CA000567802A CA567802A CA1295103C CA 1295103 C CA1295103 C CA 1295103C CA 000567802 A CA000567802 A CA 000567802A CA 567802 A CA567802 A CA 567802A CA 1295103 C CA1295103 C CA 1295103C
- Authority
- CA
- Canada
- Prior art keywords
- web
- filaments
- curing
- fibers
- air
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
- D04H3/02—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/04—Dry spinning methods
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/12—Stretch-spinning methods
- D01D5/14—Stretch-spinning methods with flowing liquid or gaseous stretching media, e.g. solution-blowing
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
- D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/69—Autogenously bonded nonwoven fabric
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Health & Medical Sciences (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Epidemiology (AREA)
- Hematology (AREA)
- Materials Engineering (AREA)
- Dispersion Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Nonwoven Fabrics (AREA)
- Orthopedics, Nursing, And Contraception (AREA)
Abstract
Abstract Superabsorbent articles in the form of soft, nonwoven fibrous webs are produced from aqueous,fiber-forming polymer solutions by forming the polymer into water soluble filaments, contacting the filaments with a primary air stream having a velocity effective to attenuate and to partially dry the filaments, contact-ing the attenuated filaments with a secondary air stream having a velocity effective to fragment the filaments into fibers and to transport the fibers to a web-forming zone while also further attenuating and drying the fibers, collecting the fibers in reticulated web-form in the web-forming zone and curing the web to a water insoluble state. The temperature and air stream velocities are controlled with respect to am-bient humidity and water content of the fiber during the fiber and web formation such that the fibers are collected without sticking. Collection is preferably on a wire belt followed by transport through a curing oven to compacting rolls and web take-up.
Description
l'h9S103 PF 50-01~ 61 Production of ~vnwoven F~brous Articl~s ~ ~d Thi~ lnventlon ~@l~te~ to ~ process oz producing ~uperabsorbent ~rticl~ ln the forra of 80f t;
nonwoven ibrou~ w~bsO The nollws~Yen w~b ~ater~al can be UB~2d p~ or can b~ coq~blned wi~h ot~r flbrous ~at~ lQ to fo~m co~poslte~ havlng a ~ide ~r~rlety of ~ppllcation~ cluding di~pe~, szln~ta~ pkins, inconti~ c~ products, ~ , ti~u~, and oth~r pro~uct~ ~og the ~bt3s~ptlon of signi~ n~- quantlti~
o 1uld~ ln~ludlng body exud~t~ and aqu~ou~ compoBi-tlon~ o;~ ~11 klnd~3~
lO3 Th~ web form~tion proce~ crltical in the product1On of all msnwov~n ~r~ides. Web~ are pro-duced with ~ domln~nt f1ber orlent~t~on in ~ known manner b~ te~ctile machine~ such ~ card~ or g~rnet~s.
It ls ~l~o known to formw~b~ wherein the flber~ h~ve a random ~rrangemen~ ~y lay~ng down on a moving ~
flbars c~rr1ed ~y a 13tr~m o~ nert ga3 such ~!18 air. ~yplcal proce~8e~ o~ tl~e latter type ln~lude the mlxing of melt-bl~wn fibers b~ h~gh veloclty 9 strezm~ fro~ 8ep2rate ~ourc~ 18 in ~& Pater!~
3,016,599, 3,502,763~ 4,100,324 And 4t263~2~1. Other patents whlch use ga~ 8tream8 ~n ~b fonn~tion lnclude U.S~ P~tent~ 3,670,731, 4,235,237~ 2,9û8,469, 4,102,963, ~,375,447, 3,755,028, 3,010,161, 2,5~0,282,
nonwoven ibrou~ w~bsO The nollws~Yen w~b ~ater~al can be UB~2d p~ or can b~ coq~blned wi~h ot~r flbrous ~at~ lQ to fo~m co~poslte~ havlng a ~ide ~r~rlety of ~ppllcation~ cluding di~pe~, szln~ta~ pkins, inconti~ c~ products, ~ , ti~u~, and oth~r pro~uct~ ~og the ~bt3s~ptlon of signi~ n~- quantlti~
o 1uld~ ln~ludlng body exud~t~ and aqu~ou~ compoBi-tlon~ o;~ ~11 klnd~3~
lO3 Th~ web form~tion proce~ crltical in the product1On of all msnwov~n ~r~ides. Web~ are pro-duced with ~ domln~nt f1ber orlent~t~on in ~ known manner b~ te~ctile machine~ such ~ card~ or g~rnet~s.
It ls ~l~o known to formw~b~ wherein the flber~ h~ve a random ~rrangemen~ ~y lay~ng down on a moving ~
flbars c~rr1ed ~y a 13tr~m o~ nert ga3 such ~!18 air. ~yplcal proce~8e~ o~ tl~e latter type ln~lude the mlxing of melt-bl~wn fibers b~ h~gh veloclty 9 strezm~ fro~ 8ep2rate ~ourc~ 18 in ~& Pater!~
3,016,599, 3,502,763~ 4,100,324 And 4t263~2~1. Other patents whlch use ga~ 8tream8 ~n ~b fonn~tion lnclude U.S~ P~tent~ 3,670,731, 4,235,237~ 2,9û8,469, 4,102,963, ~,375,447, 3,755,028, 3,010,161, 2,5~0,282,
2~411,660 and the melt-blown fiber procesEe~ dlsclosed ln ~ Patent~ 3,442,633, 3,497,337, 3,357,808 and 11,6~4,313~ A wid~ vari~ty of ~iber types ~re dis-clos~d in the oregolng patents; lnc:ludlng natural and ~ynthetlc fiber8 and ~lbe~ formed from wa~er-lnsolu-ble ~d~ogels includlng T~al~lc an~dride copolymer gels swh ~ di~clos~d 1n ~.~ Patents 37901,236 ~nd 4 ~610 ~67~Bo q!h~ hlgher the ab~orbency of a flber the ~o~a dl~1cult lt 1~ to ~ormw~b~ of the m~t~rial h~1ng th~ requil31te sotnes~, fl~xibllity And den-~ty, particularly when th~ precur~or polymer u~ed to ()3 PF 50-01 1 g6 1 -3-prepare the ~ibers 1~ tn solut~o~ During th~ web format~on proce~s the lnherent hygro~;coplclty of the fiber~ y Ca~U8e ~h~ ~lbe~ to plck up w~t~r ~rom the en~lronment with th~ con~equence th~t lf ~h~ iElb~rs are o~Ter-d~d dur~ng the pro~ss, void~ will form ln 'che web ~nd ~he ~deb will ~rack. C)n the other h~nd~ lf th~ fibers are over-w~t ~e web will b@co~ne brittle du~lng a ~ubsequent curlng ol?er~tlon. ~h~ re~ul ting web ln both ca~es w{ll have poor ~ntegrlt~ ~nd lack the den~ity, ~oftne~s ~nd flex~bili~y de~lre~
A proces h~s now be~n found ~hich comblne~
fiber and web form~lon in such manner that super-absorbent nonwoven webs c~n be produced, batch-w~e but pref erably continuously7 wh~reln conditions are controlle~ to provlde unlorm density (de~irably of about 30-200 g/m2), lnt~gr~l but r~ndom ~lber dl~-tributlon7 and the flelslb~ and softne~E~ iLmport~n~
for u~e o thew~bs ln~ater absorb~nt p~r80n21 care produc~s. The superab~orb~ncy o~ the webs 18 d~non~tr~t~d b~ th~lr abillty to ab~orb many times th2ir weight o~ w~ter nnd ~qu~ou~ 501UtiOn~l~ on th2 or~er o 40 to 1000 gram~ oE w~ter or aqueous 801ution pe~ gr~m oiE w~b materl~l under ~ree E~welllng cond~tions ~nd ~o r~aln ~ rly l~r~e qu~n~itl~s of aqu~ou~ flulds under pre~sure. ~ter" and ~aqueous ~luidsa 1l3 hereln ln~e~nd~d ~o mean and lnclud~ not ~Z95~L03 ~ ~0-01-1 96 1 -~-only wa~er.per 8e bu~ o el~ctrolyte solu~c~on~, body 1 ul d~ ~nd aq ueou~ 801 ut i on~ of al 1 ki nd~ .
~n on~ aspect of ~ lnYen~lon, nonwoverl f~b-rous web~ ~are produced f~om ~n aquesu~ solution of a flber-formlng polymer compositlon whlch initl~lly 1~
wa~er solubl~ bu~ b~com~s water ~nsoluble and ~up~r-abfiorbent upon Guring~ where~n the polymer ~olution 1B
formed into fllament~, the fll~sments are ¢ontacted with ~ primary a~r ~tream h~vlrl~ a ~eloc~ efect~e to atter,u~t2 the fll~ments~ attenuated fila~ents ~re contacted ln 21 flber ~ormlng zone ~lth a secoad~ lr streun ha~rin~ a velocit~ eff~ctive to urther attenu~te and to f~agment the fll~men~s lnto fiber~ and éo tran~-port the fiber~ to a web forming zone, the iber~ are collected in r~tlculated web form in ~he w~b-forming zone, and the web i~ cured~ E~ch air stream al80 evapo-rates wa'cer from the filaments and fibers (~he second~ry air s~cream mors ~o th~n ~h@ primary air stre~m), the flber~ thareby belng drled to th~ exten~e that the~ will collec'c and cur~ to a 80:Et web without ~ub~tanti~lly fl owing or stickin~; ~ogeth~r.
In another as~pec~, nonwovon w~b-produclng app~r~tu~ 1~ pro~rid~d, ca~lpri~ing the combin~tlon of mQan~ fo~ ~Eorming an aqueou~ polymer solution into flla-~nts, ir~t ~ upply m~n~ ltloned to dlrect an alr str~uu upon ~nd to ~rtially attenu~te and dry the ~ilam~nt~, a houslng h~vlnq oppo~ing inlet ~nd outlet ~3~3 mean~, ~econd ~ir ~upply me~n~ ltion~d ~o direct ~n ~r ~tream upon 'ch~ il~@nts for furth~r a'ctenu~tlon ~nd for ~ragmen~catlon ~h~reo, and to ~u~ther dry ~nd to c~rry the filam~n~s through ~he lnle'c ~n~ c~u~let of the S hou~ g, a ~or~inous ~ur~ace ~t the ou~l e~ of th3~
houslng or coll~c~ing ~h~ ~raglaen~ in w~b form/ ~uc-tion means ~djac~nt ~o the foramlrlou~ ~urf~c~ to ~n raln the r~gments on ~he ~ur~ac~ n~ n~ ~or curing the web on ~h~ for~lnous ~urfaceO
a Other aspect~ o~ the in~ntlon lnclude ~ non-woven w~b-produclng proce~s wher~ln the polymes co~po~i-tlon from ~hlch th~ flb~r~ of ~he web ar~ produced i~ ~
earboxyllc polyan~r cros~; link~d ~ rdro~rl or he'ce~ocy-clic c rbon~te functlonallty~ and the nonwoven wsb pro-duced ~ 'che process.
Th~se and oth~r al~peCt~37 fealture~ and ~dv~n-t~ges o the ln~entlon will be app~rent fs~ra th~
dr~wi~y~ ~nd ~peciflcatloll ~hlGh follclwO
Flg., 1 i~ a ~chQ~stic oi~ apparatu~ useful in the proco~a of th~ lnve~ntlor~ ~nd includ~s lderltlflc~-tlon o t~o ina~cr ~tep~ o~ the procl~8t Fl~. 2 1~ a v~rtical 0~c'c~0n of on~
Q~bodiDI~nt of ~n ~ctru~ion dio u~ul ln the fll~ment PF 50-01~1961 -6-formatlon 8~:ep o ~che proce~s7 and ~i9. 3 i8 a ver~lcal ~ection along the llne 3-3 o ~ 2 ~howing o~her ~truc'cure o ~h~ e~ru-sion di e of Fî 5~o 2 .
~ ~LI~
With reerence to Fig. 1 of ~h~ dr;~wing~ ln the fll~m~nt forming ~tep of th~ lnventlon a hydrop~lllc polymer 801ution ~uppli~d fr~m one or ~or~ f~ed t~nkR, such as ~te~m-he~ted and motor (Pq) ~g~t~t~d polymer ~ed tanks 10 and 12, i~ pumpQd by pu~p 1~ having a flow control (F) vla llne 16 to fil~m~nt form~ng mean~ such as an extru~ion devlc2 18. The ~xtrn~ion d~ice may hav e any ~ui t~bl ~ de si gn ~ ncl udi ng one or mor e noz z 1 es, spinneret~ or die openings. Figs. 2 and 3 ~11 ustrate one embodtm~nt of ex~rusion dev~ce in the fo~m o~ a die (descrlbed ln detall below)O The Yi~cosi~y of the poly-2~ mer so1utlon 18 regulat~d by the ~olld~ con~ent of the poly~er COlllpO8itl0n ~e~d s~ock ~nd te~p~r~ture thereof ~or an efflcient rat~ of ~xtru~lon. ~tlng the poly~ner feed up ~o about 200~DF ~ nece~s~ ccanpll~ed by ~team ~ ~akets or oth~r means. For ~xa~npl ~, at ~ ~ol ld~
co~ n~cr~tlon o ~boul: 25-60~t, preer~b~y about 35~55 and an ~xl:~u~lon devlc~ comprls~ng a bank of no2zle~
with op~nlng3 ogE 0.02B lnch dl~t~r, ~ 3ult~bl~ ex'cru-~ion ra~ bout 2.5 grals~ per ~lnut~ per nozzle at r oom t~p~r~tul:o (c~.70 F3 . I~ th~ '~3X~CE u~lon devl ce ~5~0~3 PF 50 -01-1 g6 1 ~ 7-~ncludg~ a ~1~ h~Ylng~ for ~xample, ~ leng~h of about 3-10 ~nche~ ~nd 6-12 hole~ per lnch9 the hole~ belng ev~nly ~paced arld 01~020 inche~ 1n d$~et~r, ~ ~u~tabl~
extru~lon r~to 1R ~!lbOUt 0.~!5 to 5 grnNIs p~r ~n~nut~ per hole 1~ roam t~mp6!r~l:ure. OE cour~e, ~he ~x~ru~ion rA~e wil 1 ~ eEs~nd upon the ~pe and charact~r of the po lymer ca~po ~l tlon7 p~ tl cul ar ly 1 ~c ~ v l ~ co ~i ty.
Whll~ hydroE~hillc ~horDo~ettlng ~nd ~herm~
1~ plastlc poly~e~ cQ~npo81tion8 of all typ~ ma~ be u~ed ln the proces~, ~uch a~ the polyme~ pe~ de~crlb~d ln t~nt~ cl~d abo~, the proce~ ha3 particul~r ~pplicabllty to f~ nt andwebform~t~orl froqn ~ polymer corapo~ltion compri~lng ~ bl~nd o~ a copolymer of at lea~ one alpha, be~-unsa~urated car-boxyllc monomer and a~ leaRt on~ monomer copolymer-izabl~ therQwlth, and ~2) a cro~-llnklng a~nt h~Ying crosslinklrlg ~unctiorl~llty compr$slng hydro~l or het~ro~y cl i c car bonate group~ Mor~ par tl cul ar ly, the polymer compo~itlon i~ ~ blend of a copolymer of th~
foregolng t~p~ having about 20-~0 we~ght perc~n~ p~n-d~nt c~rbo~rllc acid group~ and about 80-20 ~eight percent p~ndant carbo~ 'e~ group~, and ~ ~ul~abl~
hyd~oxyl or O-het~ocycl ic ~rbonate-contalnlng cross~
llnker ~
Th~ copoly~r o~ pDly~ner cor~ ltlon Dlay cont~iln ~bout 25-75 mol~ p~ nt recurring unit~ of at leafit ~ .,,~, ~35~03 PF 50-01-1961 D8_ vne alpha, beta un~atur~ted monomer be~ring ~t lsas'c on~
pend~nt unit selected ~om c~rboxylic acid u~its ~nd der~va-tlve~3 of c~rboxylic ac~d unit~,, and about 75 25 mole percent recurrlng u~lts o:E at lea~t one monomer sopolym~rlzable therewith, wherein abou~ 20-80 saole percent of the tot~l pend~nt units in~rodu~ed through the recurrlng alpha, beta-unsaturated mona~er unl~ ~r~ carboxyllc unlts or whlch are con~erted lnto carboxylic ~cld un~ , and wh~eln ~bout 80-20~ of th~ ~ot~ ndan~ un~t8 are c~rbo~Eyla~ ~alt U111~:8 o~e which are converted lnto carbo~late salt units. Prefer-ably, the copolymer wlll contaln about 35-6S total mole percent of r~curr~ng unit~ of at 1 ezlst on~ al pha, beta-un~aturated ~nono~er zlnd about 65-35 tot~l mol~ percent of al:
leafit on~ copolymerizable monomer,. More preferably, the c~onomers of the copol~,~er will be pres~snt ln equimol~r pr opor ti ons .
Suitable hydroxyl-contalning c~osfilink~ng unit8 include one or mor~ compound~ having a'c least two ~droxyl groups, ~uch a~ ~1 Icylene glycol ~ of 2-10 ¢arbon ato~n~ and ethers th~reo~r ~yclic alkylene glycols" bisp~enol A~ hy-dro~ alkylen~ da~lvati~e~ o bisph~nol ~, ~droqulnone, phloroglucinol, ~dro~ ~lkyl~n~ deri~Jat~va~ of dlphenols, glyco~ol, eryt~ritol, pent~eryt~ltol, ~ono~ccharidea and oth~r eo~pounds ~pacl1ed h~rein~t~r.
Suit~bl~, alpha, beta-unuatura'c~d monomers ~re tho~ ~Qaring æt lea~é one pendant carbo~yllc acid unit or d~rl~a'elY~ o~ a c~arbos~lic acld unlt. r~Q~ivative~ or ~Z~ 3 P~ sa-olls6~
carboxylic. ~cld units lnclud~ carboxyllc ~cid ~alt group~, c~rbo~llc acid ~nlde groups, carboxyllc acld im~ d~ group ~ ~arboxylic ~cld an~rdride group~ and c~ ylie ~cld e~er group~.
s q~yplc~l ~lpha9 b~a-un~a~ur~ted monomer~
u~eul in the lnv~n~lon include mal~c acld~ cro~onic ac~ d, fumarlc ac$d, me~aconic acld, the ~odl~n ~1 S o~
maleic ~cid, ~ho ~odlum aal~ o~ 2-m~t~17 2-bu~n~
dlc~rbo~llc 3c~d~ th~ 80dil~1 ~alt o~ aconlc ~cld, maleamic ~Lcid, Tllale~mld2~ ~ph~nyl m~lelmide, ~al~l-mlde, malelc an~ydride, f~na~ic anhydride, ltaconlc an~dride, c~traconlc an~drlde, m~thyl ltaconlc anhydride, ~t~yl malelc ~nhydr~d~ diethylmalea'ce~
methylmale~te9 and the l~k~, ~nd any mlxture~ ther~sf~
Any ~uit~ble copolymerizable comonolller can be empl oy~d~ Sul tabl e copolymer iz~bl e comonoq~er 8 incl ude ethylene, pro~ylene, l~obutylene, C~L to C4 al kyl (meth)~cryl~tes, vlnyl ac~tatet methyl v~nyl ether, isobutyl vlnyl *ther, and atyrenlc compou~d~
havir~g th~ ~o~mulas R ~ 2 wh~re~ln R repre~nt~ ~rdrogen or ~n alkyl group having ~Ero~ 1 to 6 ca1~bon atoms and wh~r~ th~ benzene rlng 5~03 PF 50-01-1361 -10~
may be sub~titu~d with low molecul~r welghlt alkyl or hy dr o~ gr ouRs.
T'ypical ~ C~ ~lkyl acrylates ~nc:lude methyl acryl~te, e~hyl ~cryla. e, l~opro~l ~cryl~e, n-pro~yl acrylate, n-bu'cyl acryla~e~ ~nd the like~ an any mlxture~ thereo~a ~uitabte Cl to C4 alkyl T~t~-c:rylates include ~ethyl ~ethacrylate, ethyl methacry-lat~, isopropyl methacryl~e, n pro}~ eth~cryla~e, n butyl M~thacryl~te, and the like, and any m$xturo~
thereo~ Suitabl~ ~tyrenic s:~mpounds include ~tyren~, alpha-methyls~yrene, p-m~thyl~tyrene7 t-butyl 4tyrene~
and t~e llk~ ~nd ~ny m~xtur~ thereof.
The p2ndant units on th~ al pha~ beta-unsaturated monomer~ will determlne what, if any, additional r~ac~cions mu t be carried out to ob~caln a copolymer havlng the requlsl~e pendant unit~ nece~ary to produc~ wats~-absorbing E~olymer compositlon0 useful in the lnventlon h~ing about 20-80 percent perld~nt groups ~uch ae carbo2~yllc ~cid unlts ~nd ~bout 80 to MboUt 20 perc~nt pendant carboxyl~t~ sal~ unlta Pref ~r~bly~ both unlt~ ar~ pEesent ln an ~ount o ~ro~ about 30 'co ~bout 70 percent.
~ n gen~ral~ if the ~lpha, beta-uns~tur~t2d monQmer b~ar~ only c~rboxyllc acld amid~, c~rboxylic acld ~mlae, ca~boxylic ~cid anhyd~id~ c~rboxyllc: acld e~ter group~, or lalx'cur~a the~eof~ lt ~ill b~
~5~0~3 PF 5û-01 1961 n~ce~sary to conver~ a~c le~st a portlon of such carboxylic acid derlsra~lv~ groups ~o car~a~lle ~ld group~ by~ for ex2nnple, a ~dro~y~i~ re~ction. ~f ~he alpha, b~ta-uns~turate~ ~onomer b~ar~ only carboxyllc acid salt group~, ~cld~glc~tion to ~or~ car~xyllc acid group~ wil 1 be~ n~ce~sary.
~lmll~rly9 the inal copolym~r mu~t con~in abou'c 80-20 percent pendant c~rboxyl~te sal1: unit~.
Accordingly, ~t ~y be neceQ~ary to carry out a neutr~lizatlon reactionL lileutr~llzatlon of c~rbo~llc acid gEOUpB with a ~trong org~nic or ~norg~nic b~s~
such a~ ~0~ 0~, ~onla, an~nonla-ln^w~t~r ~olution, os organic ~min~s wlll resul~ in the ~ormation of carboxyl~te salt unlt~, prefer~bly carbo~ylate metal sal t unlta ~rhe sequenc2 ~nd the numb~r o~ re~ctions droly~ls, acldlflc~t~on~ n~u~r~l lzation7 etc.) carrled out to obtain the de~lred functionall~y ~ttach~d to th~ copolym~r b~ckbon~ are not crltlcal.
Any nu~ nd ~equenc~ re~ultlng ln a final copolymer which po~ss about 20-80 percer~ pend~nt carbo~yllc acld unlt~ and about 80-20 perc~n~ pend~nt carbo;yl~te ~alt uni'c~ ultabl ~.
On~ copolymer ~rtlcul~rly sultable ~or use ln gormlng ~upar~b~orbent w~bs in ~ccordanc~ wlth the lnventloal 1~ a copoly~e~ of malelc anhydride and ~S~C)3 PF 50-01-1961 -ï 2-l~obutylen~ Anoth~r i~ maleic ~nhydride ~nd styren~O
Sui~able copolymer~ will hav~ k molecular we19hts of ~rom about 5,000 to ~bou~ 500~00û or more. The copoly~
mer~ of m~lelc aa~hydr1de and l~obutylene and~or ~tyr~rle can ~ prepared uslng any su~cable ¢onventlonal methods. M~leic ~nhydride~i~obutyl~n~ copolym~rs are a1BO coDm~rc~ y ~v~ilable r~ ~urar~ opr~n~
Chemlc~ ny, I~tdo~ Tokyo~ J~pan, und~c the trade-m~rk IS~A~ I~OESAM copoly~ers ~re ~vallable in ~ev-~ral grade~ which are d1fferenti~ed It~y Yi~cosi~
molecular weight: ISOBAM-10, 160,000 to 170,0003 ISC~A~-OS, BO,OOO to 90,QOO~1 IS09~AM-04, 55,000 to 6~,000~ and ISa~AM-600,, 6,000 to lO,OOO.
To produc~ walter-absorbing polymer comps: si-tlons usef ul ln th~ lnventiont at l east one copolymer as described about and at least on~ cross1inking com-pound bearing ~t 1east two hydroxy1 or heterocyc11c c~rbon2te groups are blended ~uch that the water-absorb1ng compo~ltlon cont~ins ln welght p~rcent about 80-99.5 tot~1 copolymer ~nd about 0.5-20 tota1 cro~s11nk1ng ca~pound. Pr~f~r~bly, the ca~nposition wlll corltaln about 90~99 welght percent tot~1 copo1~e~ and ~bout 1-10 weight p~rc~nt total cross1 ink1ng ~gent.
i Any suitable org~nic compound be~ring at 1~ast two ~roxyl or heterocyclic carbonat~ gzoup~
and havlng 2 r~latlvely low mol~cular w~lght, l~as than 1,900" c~n be ~npl oyed ~ a cro~l inking ~g~nt f or th~ copolymer a Sui~abl~ cro~slinking compound~ include ethyl~ne c~rbon~t~ propyl~n~ carboFIAte~ 2 butylene carbonate, 2-3 butylen~ carbon~e~ phenyl ethyle3-~
carbon~te9 e~hylen~ glycol, propy~ene glycol~
trimethylene glycoly 1,4-butane diol, 2-metbyl-1, 3-propane diol, neop~ntyl glycol, 1 ~5-p~nt~n~ diol ~
diethylene glycol9 dlpro~ylene glycol, 1,4-cyclohe~ane dlme'chanol, Bisp~enol A, 1,4-b~s (beta-~dro~'cho~y) bl~phenol, }~droquinone, phlorogludnol~ glycerol~
erythritol, pentaerythrltol, meso~erythrltol; 1,7-dihydroxysedoheptulose, sucrose, natur~l mono~a~cha-rides, ~nd th~ like, including ~ny mixtures thereof,.
In the filament forming step (again, with reference to Flg. 1), 4he polymer filamen1: 20 ~8 contacted wlth a primary air stream diracted generally vertic~lly fro~ noz~le~, opanings in ho~zont~lly posltioned tub~ or other me~n~ a8 ~ ave~ the extruder 18. Tho ~ir i~ supplled by ~ compr~ssor bl~wer topera~g.ng up to about 25 p8i) or other ~u~t~bl e 80ul:ce. ~he ~loclty oi~ the air ~tream t~ selected to Rartl~lly dry ~nd attenu~t~ t~le flla~ents to ~ diameter 3ufficl~nltly ~nall ~uch that th~ n'c~ will be further ~ttQnuat~d and will ragm2nt e~lly when con~c~ed wi'eh a ~econdary air ~ream ra~ nozzle 22 ~uppl ied ~ro~ a bl cwer 24 through a ch~ r 26 .. Blower 24 mAy be pro-rided w~th ~ su~cable controller (C~ and fl~w lndlcator ~F). A prim~ry ~ir ~r~am v~locity (mea~ured 6 inche~ rom ~he a~r exit~) o at 1 east abou~ S00 ~e~t per mirlute (f~ .9. r abou~ 500-8,000 fpm, ~ e effective. qhe ~ec:ondary a~ ~empera~ur~
in tunnel 34 may be ~egul~te~ ~y ~team flow ln line 28 to ~ he~t exchanger 30 ln chamber 26. i~ convention~l tempera~:ur~ ~ensor (T~ ~nd controll~r (C) regul~tes th~
temperatuse 'chrough a ~uitable control valve i!snd control v~lY~8 ~ctuator al8 sho~n. Fil~nent~ 20 will h~ve diameter~ of abou'c 5-20 mlcron~ aa a re~alt of the entralr~nent and attenuation by the primary air ~tream.
When cont~cted ~ the high velocity s~condary air ~tream from nozzle 22, ~lowlng at a velociLty of at least ~bout 3,000 feet per ~lnute, e.q~,, about 3,0ûO to 10,000 fee~- per mlnute o~ greater, the filaments 2a are further attentlla'ced ~nd dried, and ~re fragmented in~co flber plece3 3~ whlch are carr~ed by the ~econdary air and v~porlzed water through the houslng or tunnel 34 h~ving an lnl~t adj~cent the nozzl~ ~2 &nd an oppo~ing outlet. ~rh~ flber~ then depo31t on ~ for~lnou~ col-lector ~ur~ace such ~8 ~ 13creen 36 positloned ln the outlet o~ th~ 'cunnel. 5c~een 3~ prefer~bly ~LB ~ounted or po~ltlor,~d alt an ~ngle to the longitud~nal a2i~ of tu~n~l 3~, ~g., about ~5, The t~mperatur~ and humidity ln the ~cunnel 34 a~e 8ensed and regulat~d ~uch th~t th~ wat~ content of ~rsgmen~c~ 32 a~ they collect on ~creen 36 18 i~boU'C 10-15 percent b~ welght. If the f~ber fraç~ment~ are over-drl~d at ~hls polnt the resultlng web will contain void~ and sub3equently crack ~ur~ng the curing ~te~ If the ~ibers ~re too molst the w~b wlll b~come brl tle during th~ ~ub~equent cur-ing. ~h~ secondary a~r ~es~Q in ~dd~on ~o fra~ment-ing ~nd drylng ~he flber~, ~lu9me~ B ~ch~ attenual:lon of the flber~ to ~he desired 5 20 mlcron dla~eter r~nge.
Tunnel 34 1~ dimen~ioned 'co ~'ctain the pro-per ~oi~ture content in th~ 1bers ~8 th~y collect on ~creen 36. ~ nel hou~ing ~bout 12 feet long z~nd havlng lnter~or di~en~lon~ of abou~ 3 feet by 3 feet 18 suitable but oth~r dlmen~ons will Ib~ effeotlve depending upon the water con~c~n~c of the polymer compo-~itlon aR it 1~ formed into iE~l ament~, the h~dro~copl-city of the polymer co3npositlon, ~nd the ext~nt to which the polymer composit~on i~ neu'cralized and c~o~-llnk~d. Pa~s~ge of ~he flbers thxough the tunnel a~
well as t~mperature ~nd hlmlldlty control 18 facili-tated b~ llnlng the tunnel with sultably ~urfaced insul~ting material~ such ~s gla~s fib~r battlng ~ur-f~cod wi~ch a wa~r i~Qper~ious film. Whlle nozzle 22 and 'cunn~l 34 2re ~hown lhorizontally po~i'cloned in Fig. 1" ~r~rticz~l or other positioning m~y al~o b~
prac1:ic~d.
Coll~ction o~ th~ fi~ ~ag~ent~ 34 on the scEe~n 36 1~ f~clll~t~d by a suc~ion g~ner~t~d by blc~ O which pu118 s0condary ~lr ~om tunnal 34 ~L2~5~ 3 PF S0-01-~ 961 -16-~hrouyh ~n exh~uRt chamber 42. The ~uctlon al ~o minl -mize~ cond~nsatlon of water on th~ interior ~all~ of tunnel 34. The dif~erentlal pressure o~ the ~uctlon generated k~ blower 40 i~ regulatad ~y ~ controller (C3 Jsnd ~e~sured by a pre~aure ;en~or (P~ ~cross ~he ~r~en 36. Th~ 6uctioned a1 r i8 exh~usted through stzlck 41 and ~her~ 80 cr~a~ce~ ~ pr~s~ure dlfferent~l to hol d the web ln pl ~c~ on ~he scre~n 36 during lnlti~ ssage in~o ~che oven 38.
Although ~reen 36 laay comprl~ a Pixed sur~ce or a rotatlJ~g dr~n ~eparat~ fro~ tunnel 34, pr~erably ~creen 36 i8 a. for~minous wlre or wlr~
mesh belt as ~h~7wn, whicll ~oves continuously throuqh a curlng oven 38~, Moi~ture ~en~ors ~4 having ~ readout M determine whether the ~ibrous mater~al on th~ wire haæ the requisite moisture content a~ i'c enter~ the overL q~yplcally" the moisture should be le88 than 20 by we$gh~ a8 ~che material enters ~he oven~ to prevent the fiber~ ~ro~ flowlng ~d stickin5~ ~cogether, ~chereby lo~lng ~iber lntegrlty. ~o ~lber ragm~nts now coll~cted on ~ch~ wir~ ln web ~orm ~re mo,intnlned on the wire durlng p1~88a9e through the o~r~n by alr pressur~ ~g~ t one ~ide of th~ wlre and ~uctlon from the oth~r slde g~ner~t~d by air cycled by ~ blow~r ~
fro~ ~L ~uctlon conduit 480 ~he alr 18 tr~n~po~ted ~ia a ~upply ¢ondult- ~9 to a dl~tributlon reglon 50 ~ub-dlvlded lnto ch~nb~rs or menlfolds (not ~hc~wn) po~ltiLonea on one sldo of e~ch o~ the vertlc~l wlre~
~5~C~3 PF SO-Ol~î 961 -17~
~hclwn ln ~lg,. 1~, ~r ~hu~ ~uctloned through one f ace of the wl~ collect:ed in an exhau~ region 51 ad~acen'c ~he oppo~ing ftlc~ of the wir~ ~o compl~te the ~lr iElow cycle. ~ heater 52 de~lrably 18 moun~ed ~ap~t~c~ oP blow~r 46 to h~at ~he air ~tr~am a~
required for curing o} the~ weh ~uitable t~mpera~ure ~ontrols ~T~C~ ~re provlded ~co relate ~i r ~p~ratur~
in th~ ove~ ~o ~pe~d o th~ ~ir~ ~nd oth~r parame~ers for e~ ient cu~ e alr pre~ur~ acros~ wlr~s 36 1 measu~ed b~ ~ ~en~o~ 54. A21~r design of curing ov*rl, and ~1~ supply ~nd ~Jchau~t ~y~m of ~he curing ~a~ren) ~uitable~ iEor ob~alnlng ef~icien~ cure c~n be u~ed. Or~e such deslgn is the oYen and alr dis~rlbution ~ em commerci~lly available from E~on~ycomb Syxt2ms, ~nc., of Blddeford, M~lne.
An oven temperature o~ about 25ûC ~or about 5 minu~es resldence time or abou1: 270~C for ~bout 2.5 minut~ re~ldenGe ~ime provides good cure but lcw~r t~peratures and ls~ng~r residcnce times are ~1BO
suitabl e, ~uch ~8 about 210C: ~o~ about 20 minute~.
~igh~r t~mp2r~cur2s c~n b~ u~ed wlth concomitantly lower re~onanc~ timeEI provlded th~ ~rebs do not di~color,, Generally" ~he oven temperatur~ range may bo ~bou~ 150-275C fo~ re~ld~nc~ 'clm2~ of ~b~ut 35 -0.5 ~nut~.
~pon ~mer gi ng ~ rom the cur i ng o~ en, pr oduct w~b 56 ~lrably 1~ comp~ctod ~ ~ny ~uit~bl~ me~n~
~2~ ()3 ~uch as n~p roll ~ 58 and 60, ~nd 1~ t~n~ported ~o ~
ta k~-up st~ti on 62 wher e i t i c wound on an 1 dl er ~pool 6~ drlven b~ 8pool 66. A ~ension controll er (Y) re~ul~te~ take-up 'cen~ion in a known ~nanner~ If d~s~red~ @mbos~lng roll~ may be u~ed for the cGmpac~on to improve ~h~ integrity ~nd appe~rarlce of th~ ~b by decrea~ins~ ~he vislbll1ty of ~3mall dls-continu~tle~ in the web.
Fig~. 2 and 3 lllustrate one embodiment of a die ~ultable ln for~ing the ilament~ $n ~xtru~lon de~rice 18. With re~Qrenc~ thereto, a die he~d comprl~e~ a dle head cover 68, one or more entry condults 69, and a chamber 70 definlng a manlfold for entsy of polymer syrup through channels 72 ~o nozzle feed chamber 74. The nozzle chamber i~ d~f ined ~y tip body 76 and conununicates wiéh dle holes 78. Fllaments 80 ~re thl3s ex'cruded and en~rained by prlmary air 8tre~!all8 82 and R3 in~ected from openings in supply tube~ 84 and 86. Suitable alr ~upply tube~ may be about 10 inch~s long and have 12 hol~ p~ lnchwh~rein the hol ~ dl~Reter il3 0.020 lncl~. q!ne vel oc~ ~y ~nd Angles o~ lmpingemen's o ~ir stream~ 82 and 83 upon fil~ent 80 ~r~ s~lected rel~tlve ~o the vl~co0i~y of the polyme~ l3yrup ~nd tha location o th~ ~e~ond~ lr ~3tra~uo 8uch that fll~nent8 80 will b~ entralned and att~nllat~d éo the de~ r2d dlam~ter range. A ~uit~ble angl2 og lm~?lngement i8 20 d~gree~ An ~ir knlf~ may b~ u~s~d in plac~ of tub~ 8~. and 86, if d~slr~d.
PF SO-Olol 961 -19 Thu0 b~ prac~clce h~ th~ proce~s of the ln-ventlon, 0uperabsorbent web~ of unlform den~lt~ and h~ving the requl~ sof~ne~ and fl~xib~ll~ ar~
S produced cs~ntlnou~ly and ~~1cien~1y. q~he re~ultlng web le dry to th~ touch and c~la be convenlently :Incsr-por~te~ into varlouR product ~orm~ ln accorda~c~
w~ known pro~edure~.
Th~ following exampl~ ~ill 8~rve~ in cor ~unct~on wlth l?igs. 1-3, as ~urth~r ~llu~t~ation of the lnvention.
~9 L
A polymer Eiyrup i~ pr~p~red, comprlsing ~
409~ polymer ~olid~ ~ol ution of a mal eic an~ydrld~/~ o-butyles~e copolym~r h~vlng a vi~cosity ~verage - molecular wei~ht of about 160,000-170,0ûO ~nd wh~h i8 503 neutgalized with ~od~um lt~droxld~ and erosslinked wlth 7 phr o~ p~oE~rlene ca~bonatQ per (7 par'c~ by weight o~ pzoE~l~ne cArbon~e per 100 parts b~ weight of copolymer).
a! cont~nuou~ web ~ produced bsr bl~wlng f~ber~ ~rag~snt~d ~rom g~llam~nt~ ~xt~ud~d ~ram ~he ~olym~ cup through ~ ai~ t~uch a~ die 18 o~ Flg~. 2 ~ma 3) u~lng prL~ary ~ir ~nd ~cond~ ir a~
descrlb~d ho~¢ingJ,bo~e, to a web ~o~mlng ~cr~en 36 ~2~35~:)3 PF 50~01-1961 -20-coqnprisln~ a wire me~h bel t whlch travel~ through ~
curlng oven 38O Th~ polymer feed pump rat~ (Nichol-~enlth P~np, Model ~IJB-5456-30cc/r~v.~ is e~e'c ~t 3 rpm9 for ~xtru3loJl of polymer at 100 gm/mlnut~ or a~
2.6 gm/minute/hole ~n the die" The belt peed la ~et at 2.S ~et p~ minuteO The r~al ative polymer ~*ed and wire speed are ~tched to give the da~ired web derl l~y. The r~quired ov~n ~cemper~ure 18 ~hea~ set to complet~ly ~ure th~ web ln ;:h~ resldence tlm~ of the w~b ln t~ h~ted zone of the curi~g oven. ~or an oven 63 feet long and a belt of 2.5 fpn, th~ cur~
tlme i~ ~5 mlnut~. For thl~ re~ld~nce time, 195C 1 a Guitable oYen temp~ra~ur~. Once the polymer 1~
flowing ~reely through the die, the belt ~ ovlng, and the proper oven ~eqnper~ture i8 re~ched, the primary alr i8 turned on ~o reach a ve~oc~ .y o~ about 8000 fpm through the hole~ in the ~ir tubes 84 and 86 of Fig. lo Then, the secondary air i8 turned on to at least 7000 ~pm ~or thls feed rate and th~ air i8 heated ~o 125C The temper~ture o~ the secondary air ls ad~u~t~d in chamber 26 to dry 'che w~b ~s lt 1~
formed to 10-15 wt.~ ~oi~ture. ~ econd ry and prlm~ry ~ir are re1aov~d iLn ~he oYen 38 through the belt ~nd eah~u~t~d to the out~ld~ b~ exhaust blcrwer 40 and 8uctlo~a box 42 b~h~nd 'cho b~ One lnch o water : pr~s~u~e ~op across th~ web and bel'c 1~ sufflc1Qrl~c to oxhau~t tlh~ air ~nd d~ it the ~lb~rs ln web fonu on th~ b~lto Th~ exhaust ~an ~peed 1~ lncr~ased until th~ pr~s~ure drop 1~ achieved. ~h~ w~b travel~
~2~5~03 P~ 5û-~1 1 9~ 1 -21-through the oven on th~ movlng belt and 1~ removed ~
the exi~where lt can be embo~sedor simply rolledup.
A web produced a8 descr$bed has a den 1 y o~ 105 gJm2, absorb~ ~Ø2 g/g o:E 0.9% brln~ ~olutlon and re aln~
26.3 g/g of the br~n~ ~ol utîon under a pr~esure of 0.5 psi~ The wa~er~welled web i8 dry to th~ touch~, ~9 ~
Sub3~ant~ally ~ d~crib~d ln ~xample 1 l~u~c u~ing ~ polym~r fo~ul~tion dierins3 from th~t o ~xample 1 by sub~tltu~cion o~ p~ntaerythrltol and bu-t~nediol for proE~ylen~ c~rbona~e ln amounts o~ 8 phr and 2 phr, respectlv~ly, and increa~ing ~he ~elt ~p~ed to 2.8 fpm, ~ fibrous web 1~ produc~ he cure re~ldence t~me 1~ 22.5 minutes~, The oven temper~ture for thi formulation nnd resldence tlme i8 175C and the ~econdAry ~lr tempe~ture i8 lOO"C. The collector pres~ure drop on the belt 18 inc~ea~ed -o 2.0 inches ~ o~ water to dr~w th~ ~bers to the belt more evenly.
The web p~oduced ha~ a derlsi~ o~ 83 gJm2d zlbsorbs 4808 g/g o~ a 0.9~8 brine solution and retains 28D9 g~g of the brln~ ~ol ution und2~ a pr~ur~ o~ 0.5 psl. The solubllity o the polymer 18 1~6~o5
A proces h~s now be~n found ~hich comblne~
fiber and web form~lon in such manner that super-absorbent nonwoven webs c~n be produced, batch-w~e but pref erably continuously7 wh~reln conditions are controlle~ to provlde unlorm density (de~irably of about 30-200 g/m2), lnt~gr~l but r~ndom ~lber dl~-tributlon7 and the flelslb~ and softne~E~ iLmport~n~
for u~e o thew~bs ln~ater absorb~nt p~r80n21 care produc~s. The superab~orb~ncy o~ the webs 18 d~non~tr~t~d b~ th~lr abillty to ab~orb many times th2ir weight o~ w~ter nnd ~qu~ou~ 501UtiOn~l~ on th2 or~er o 40 to 1000 gram~ oE w~ter or aqueous 801ution pe~ gr~m oiE w~b materl~l under ~ree E~welllng cond~tions ~nd ~o r~aln ~ rly l~r~e qu~n~itl~s of aqu~ou~ flulds under pre~sure. ~ter" and ~aqueous ~luidsa 1l3 hereln ln~e~nd~d ~o mean and lnclud~ not ~Z95~L03 ~ ~0-01-1 96 1 -~-only wa~er.per 8e bu~ o el~ctrolyte solu~c~on~, body 1 ul d~ ~nd aq ueou~ 801 ut i on~ of al 1 ki nd~ .
~n on~ aspect of ~ lnYen~lon, nonwoverl f~b-rous web~ ~are produced f~om ~n aquesu~ solution of a flber-formlng polymer compositlon whlch initl~lly 1~
wa~er solubl~ bu~ b~com~s water ~nsoluble and ~up~r-abfiorbent upon Guring~ where~n the polymer ~olution 1B
formed into fllament~, the fll~sments are ¢ontacted with ~ primary a~r ~tream h~vlrl~ a ~eloc~ efect~e to atter,u~t2 the fll~ments~ attenuated fila~ents ~re contacted ln 21 flber ~ormlng zone ~lth a secoad~ lr streun ha~rin~ a velocit~ eff~ctive to urther attenu~te and to f~agment the fll~men~s lnto fiber~ and éo tran~-port the fiber~ to a web forming zone, the iber~ are collected in r~tlculated web form in ~he w~b-forming zone, and the web i~ cured~ E~ch air stream al80 evapo-rates wa'cer from the filaments and fibers (~he second~ry air s~cream mors ~o th~n ~h@ primary air stre~m), the flber~ thareby belng drled to th~ exten~e that the~ will collec'c and cur~ to a 80:Et web without ~ub~tanti~lly fl owing or stickin~; ~ogeth~r.
In another as~pec~, nonwovon w~b-produclng app~r~tu~ 1~ pro~rid~d, ca~lpri~ing the combin~tlon of mQan~ fo~ ~Eorming an aqueou~ polymer solution into flla-~nts, ir~t ~ upply m~n~ ltloned to dlrect an alr str~uu upon ~nd to ~rtially attenu~te and dry the ~ilam~nt~, a houslng h~vlnq oppo~ing inlet ~nd outlet ~3~3 mean~, ~econd ~ir ~upply me~n~ ltion~d ~o direct ~n ~r ~tream upon 'ch~ il~@nts for furth~r a'ctenu~tlon ~nd for ~ragmen~catlon ~h~reo, and to ~u~ther dry ~nd to c~rry the filam~n~s through ~he lnle'c ~n~ c~u~let of the S hou~ g, a ~or~inous ~ur~ace ~t the ou~l e~ of th3~
houslng or coll~c~ing ~h~ ~raglaen~ in w~b form/ ~uc-tion means ~djac~nt ~o the foramlrlou~ ~urf~c~ to ~n raln the r~gments on ~he ~ur~ac~ n~ n~ ~or curing the web on ~h~ for~lnous ~urfaceO
a Other aspect~ o~ the in~ntlon lnclude ~ non-woven w~b-produclng proce~s wher~ln the polymes co~po~i-tlon from ~hlch th~ flb~r~ of ~he web ar~ produced i~ ~
earboxyllc polyan~r cros~; link~d ~ rdro~rl or he'ce~ocy-clic c rbon~te functlonallty~ and the nonwoven wsb pro-duced ~ 'che process.
Th~se and oth~r al~peCt~37 fealture~ and ~dv~n-t~ges o the ln~entlon will be app~rent fs~ra th~
dr~wi~y~ ~nd ~peciflcatloll ~hlGh follclwO
Flg., 1 i~ a ~chQ~stic oi~ apparatu~ useful in the proco~a of th~ lnve~ntlor~ ~nd includ~s lderltlflc~-tlon o t~o ina~cr ~tep~ o~ the procl~8t Fl~. 2 1~ a v~rtical 0~c'c~0n of on~
Q~bodiDI~nt of ~n ~ctru~ion dio u~ul ln the fll~ment PF 50-01~1961 -6-formatlon 8~:ep o ~che proce~s7 and ~i9. 3 i8 a ver~lcal ~ection along the llne 3-3 o ~ 2 ~howing o~her ~truc'cure o ~h~ e~ru-sion di e of Fî 5~o 2 .
~ ~LI~
With reerence to Fig. 1 of ~h~ dr;~wing~ ln the fll~m~nt forming ~tep of th~ lnventlon a hydrop~lllc polymer 801ution ~uppli~d fr~m one or ~or~ f~ed t~nkR, such as ~te~m-he~ted and motor (Pq) ~g~t~t~d polymer ~ed tanks 10 and 12, i~ pumpQd by pu~p 1~ having a flow control (F) vla llne 16 to fil~m~nt form~ng mean~ such as an extru~ion devlc2 18. The ~xtrn~ion d~ice may hav e any ~ui t~bl ~ de si gn ~ ncl udi ng one or mor e noz z 1 es, spinneret~ or die openings. Figs. 2 and 3 ~11 ustrate one embodtm~nt of ex~rusion dev~ce in the fo~m o~ a die (descrlbed ln detall below)O The Yi~cosi~y of the poly-2~ mer so1utlon 18 regulat~d by the ~olld~ con~ent of the poly~er COlllpO8itl0n ~e~d s~ock ~nd te~p~r~ture thereof ~or an efflcient rat~ of ~xtru~lon. ~tlng the poly~ner feed up ~o about 200~DF ~ nece~s~ ccanpll~ed by ~team ~ ~akets or oth~r means. For ~xa~npl ~, at ~ ~ol ld~
co~ n~cr~tlon o ~boul: 25-60~t, preer~b~y about 35~55 and an ~xl:~u~lon devlc~ comprls~ng a bank of no2zle~
with op~nlng3 ogE 0.02B lnch dl~t~r, ~ 3ult~bl~ ex'cru-~ion ra~ bout 2.5 grals~ per ~lnut~ per nozzle at r oom t~p~r~tul:o (c~.70 F3 . I~ th~ '~3X~CE u~lon devl ce ~5~0~3 PF 50 -01-1 g6 1 ~ 7-~ncludg~ a ~1~ h~Ylng~ for ~xample, ~ leng~h of about 3-10 ~nche~ ~nd 6-12 hole~ per lnch9 the hole~ belng ev~nly ~paced arld 01~020 inche~ 1n d$~et~r, ~ ~u~tabl~
extru~lon r~to 1R ~!lbOUt 0.~!5 to 5 grnNIs p~r ~n~nut~ per hole 1~ roam t~mp6!r~l:ure. OE cour~e, ~he ~x~ru~ion rA~e wil 1 ~ eEs~nd upon the ~pe and charact~r of the po lymer ca~po ~l tlon7 p~ tl cul ar ly 1 ~c ~ v l ~ co ~i ty.
Whll~ hydroE~hillc ~horDo~ettlng ~nd ~herm~
1~ plastlc poly~e~ cQ~npo81tion8 of all typ~ ma~ be u~ed ln the proces~, ~uch a~ the polyme~ pe~ de~crlb~d ln t~nt~ cl~d abo~, the proce~ ha3 particul~r ~pplicabllty to f~ nt andwebform~t~orl froqn ~ polymer corapo~ltion compri~lng ~ bl~nd o~ a copolymer of at lea~ one alpha, be~-unsa~urated car-boxyllc monomer and a~ leaRt on~ monomer copolymer-izabl~ therQwlth, and ~2) a cro~-llnklng a~nt h~Ying crosslinklrlg ~unctiorl~llty compr$slng hydro~l or het~ro~y cl i c car bonate group~ Mor~ par tl cul ar ly, the polymer compo~itlon i~ ~ blend of a copolymer of th~
foregolng t~p~ having about 20-~0 we~ght perc~n~ p~n-d~nt c~rbo~rllc acid group~ and about 80-20 ~eight percent p~ndant carbo~ 'e~ group~, and ~ ~ul~abl~
hyd~oxyl or O-het~ocycl ic ~rbonate-contalnlng cross~
llnker ~
Th~ copoly~r o~ pDly~ner cor~ ltlon Dlay cont~iln ~bout 25-75 mol~ p~ nt recurring unit~ of at leafit ~ .,,~, ~35~03 PF 50-01-1961 D8_ vne alpha, beta un~atur~ted monomer be~ring ~t lsas'c on~
pend~nt unit selected ~om c~rboxylic acid u~its ~nd der~va-tlve~3 of c~rboxylic ac~d unit~,, and about 75 25 mole percent recurrlng u~lts o:E at lea~t one monomer sopolym~rlzable therewith, wherein abou~ 20-80 saole percent of the tot~l pend~nt units in~rodu~ed through the recurrlng alpha, beta-unsaturated mona~er unl~ ~r~ carboxyllc unlts or whlch are con~erted lnto carboxylic ~cld un~ , and wh~eln ~bout 80-20~ of th~ ~ot~ ndan~ un~t8 are c~rbo~Eyla~ ~alt U111~:8 o~e which are converted lnto carbo~late salt units. Prefer-ably, the copolymer wlll contaln about 35-6S total mole percent of r~curr~ng unit~ of at 1 ezlst on~ al pha, beta-un~aturated ~nono~er zlnd about 65-35 tot~l mol~ percent of al:
leafit on~ copolymerizable monomer,. More preferably, the c~onomers of the copol~,~er will be pres~snt ln equimol~r pr opor ti ons .
Suitable hydroxyl-contalning c~osfilink~ng unit8 include one or mor~ compound~ having a'c least two ~droxyl groups, ~uch a~ ~1 Icylene glycol ~ of 2-10 ¢arbon ato~n~ and ethers th~reo~r ~yclic alkylene glycols" bisp~enol A~ hy-dro~ alkylen~ da~lvati~e~ o bisph~nol ~, ~droqulnone, phloroglucinol, ~dro~ ~lkyl~n~ deri~Jat~va~ of dlphenols, glyco~ol, eryt~ritol, pent~eryt~ltol, ~ono~ccharidea and oth~r eo~pounds ~pacl1ed h~rein~t~r.
Suit~bl~, alpha, beta-unuatura'c~d monomers ~re tho~ ~Qaring æt lea~é one pendant carbo~yllc acid unit or d~rl~a'elY~ o~ a c~arbos~lic acld unlt. r~Q~ivative~ or ~Z~ 3 P~ sa-olls6~
carboxylic. ~cld units lnclud~ carboxyllc ~cid ~alt group~, c~rbo~llc acid ~nlde groups, carboxyllc acld im~ d~ group ~ ~arboxylic ~cld an~rdride group~ and c~ ylie ~cld e~er group~.
s q~yplc~l ~lpha9 b~a-un~a~ur~ted monomer~
u~eul in the lnv~n~lon include mal~c acld~ cro~onic ac~ d, fumarlc ac$d, me~aconic acld, the ~odl~n ~1 S o~
maleic ~cid, ~ho ~odlum aal~ o~ 2-m~t~17 2-bu~n~
dlc~rbo~llc 3c~d~ th~ 80dil~1 ~alt o~ aconlc ~cld, maleamic ~Lcid, Tllale~mld2~ ~ph~nyl m~lelmide, ~al~l-mlde, malelc an~ydride, f~na~ic anhydride, ltaconlc an~dride, c~traconlc an~drlde, m~thyl ltaconlc anhydride, ~t~yl malelc ~nhydr~d~ diethylmalea'ce~
methylmale~te9 and the l~k~, ~nd any mlxture~ ther~sf~
Any ~uit~ble copolymerizable comonolller can be empl oy~d~ Sul tabl e copolymer iz~bl e comonoq~er 8 incl ude ethylene, pro~ylene, l~obutylene, C~L to C4 al kyl (meth)~cryl~tes, vlnyl ac~tatet methyl v~nyl ether, isobutyl vlnyl *ther, and atyrenlc compou~d~
havir~g th~ ~o~mulas R ~ 2 wh~re~ln R repre~nt~ ~rdrogen or ~n alkyl group having ~Ero~ 1 to 6 ca1~bon atoms and wh~r~ th~ benzene rlng 5~03 PF 50-01-1361 -10~
may be sub~titu~d with low molecul~r welghlt alkyl or hy dr o~ gr ouRs.
T'ypical ~ C~ ~lkyl acrylates ~nc:lude methyl acryl~te, e~hyl ~cryla. e, l~opro~l ~cryl~e, n-pro~yl acrylate, n-bu'cyl acryla~e~ ~nd the like~ an any mlxture~ thereo~a ~uitabte Cl to C4 alkyl T~t~-c:rylates include ~ethyl ~ethacrylate, ethyl methacry-lat~, isopropyl methacryl~e, n pro}~ eth~cryla~e, n butyl M~thacryl~te, and the like, and any m$xturo~
thereo~ Suitabl~ ~tyrenic s:~mpounds include ~tyren~, alpha-methyls~yrene, p-m~thyl~tyrene7 t-butyl 4tyrene~
and t~e llk~ ~nd ~ny m~xtur~ thereof.
The p2ndant units on th~ al pha~ beta-unsaturated monomer~ will determlne what, if any, additional r~ac~cions mu t be carried out to ob~caln a copolymer havlng the requlsl~e pendant unit~ nece~ary to produc~ wats~-absorbing E~olymer compositlon0 useful in the lnventlon h~ing about 20-80 percent perld~nt groups ~uch ae carbo2~yllc ~cid unlts ~nd ~bout 80 to MboUt 20 perc~nt pendant carboxyl~t~ sal~ unlta Pref ~r~bly~ both unlt~ ar~ pEesent ln an ~ount o ~ro~ about 30 'co ~bout 70 percent.
~ n gen~ral~ if the ~lpha, beta-uns~tur~t2d monQmer b~ar~ only c~rboxyllc acld amid~, c~rboxylic acld ~mlae, ca~boxylic ~cid anhyd~id~ c~rboxyllc: acld e~ter group~, or lalx'cur~a the~eof~ lt ~ill b~
~5~0~3 PF 5û-01 1961 n~ce~sary to conver~ a~c le~st a portlon of such carboxylic acid derlsra~lv~ groups ~o car~a~lle ~ld group~ by~ for ex2nnple, a ~dro~y~i~ re~ction. ~f ~he alpha, b~ta-uns~turate~ ~onomer b~ar~ only carboxyllc acid salt group~, ~cld~glc~tion to ~or~ car~xyllc acid group~ wil 1 be~ n~ce~sary.
~lmll~rly9 the inal copolym~r mu~t con~in abou'c 80-20 percent pendant c~rboxyl~te sal1: unit~.
Accordingly, ~t ~y be neceQ~ary to carry out a neutr~lizatlon reactionL lileutr~llzatlon of c~rbo~llc acid gEOUpB with a ~trong org~nic or ~norg~nic b~s~
such a~ ~0~ 0~, ~onla, an~nonla-ln^w~t~r ~olution, os organic ~min~s wlll resul~ in the ~ormation of carboxyl~te salt unlt~, prefer~bly carbo~ylate metal sal t unlta ~rhe sequenc2 ~nd the numb~r o~ re~ctions droly~ls, acldlflc~t~on~ n~u~r~l lzation7 etc.) carrled out to obtain the de~lred functionall~y ~ttach~d to th~ copolym~r b~ckbon~ are not crltlcal.
Any nu~ nd ~equenc~ re~ultlng ln a final copolymer which po~ss about 20-80 percer~ pend~nt carbo~yllc acld unlt~ and about 80-20 perc~n~ pend~nt carbo;yl~te ~alt uni'c~ ultabl ~.
On~ copolymer ~rtlcul~rly sultable ~or use ln gormlng ~upar~b~orbent w~bs in ~ccordanc~ wlth the lnventloal 1~ a copoly~e~ of malelc anhydride and ~S~C)3 PF 50-01-1961 -ï 2-l~obutylen~ Anoth~r i~ maleic ~nhydride ~nd styren~O
Sui~able copolymer~ will hav~ k molecular we19hts of ~rom about 5,000 to ~bou~ 500~00û or more. The copoly~
mer~ of m~lelc aa~hydr1de and l~obutylene and~or ~tyr~rle can ~ prepared uslng any su~cable ¢onventlonal methods. M~leic ~nhydride~i~obutyl~n~ copolym~rs are a1BO coDm~rc~ y ~v~ilable r~ ~urar~ opr~n~
Chemlc~ ny, I~tdo~ Tokyo~ J~pan, und~c the trade-m~rk IS~A~ I~OESAM copoly~ers ~re ~vallable in ~ev-~ral grade~ which are d1fferenti~ed It~y Yi~cosi~
molecular weight: ISOBAM-10, 160,000 to 170,0003 ISC~A~-OS, BO,OOO to 90,QOO~1 IS09~AM-04, 55,000 to 6~,000~ and ISa~AM-600,, 6,000 to lO,OOO.
To produc~ walter-absorbing polymer comps: si-tlons usef ul ln th~ lnventiont at l east one copolymer as described about and at least on~ cross1inking com-pound bearing ~t 1east two hydroxy1 or heterocyc11c c~rbon2te groups are blended ~uch that the water-absorb1ng compo~ltlon cont~ins ln welght p~rcent about 80-99.5 tot~1 copolymer ~nd about 0.5-20 tota1 cro~s11nk1ng ca~pound. Pr~f~r~bly, the ca~nposition wlll corltaln about 90~99 welght percent tot~1 copo1~e~ and ~bout 1-10 weight p~rc~nt total cross1 ink1ng ~gent.
i Any suitable org~nic compound be~ring at 1~ast two ~roxyl or heterocyclic carbonat~ gzoup~
and havlng 2 r~latlvely low mol~cular w~lght, l~as than 1,900" c~n be ~npl oyed ~ a cro~l inking ~g~nt f or th~ copolymer a Sui~abl~ cro~slinking compound~ include ethyl~ne c~rbon~t~ propyl~n~ carboFIAte~ 2 butylene carbonate, 2-3 butylen~ carbon~e~ phenyl ethyle3-~
carbon~te9 e~hylen~ glycol, propy~ene glycol~
trimethylene glycoly 1,4-butane diol, 2-metbyl-1, 3-propane diol, neop~ntyl glycol, 1 ~5-p~nt~n~ diol ~
diethylene glycol9 dlpro~ylene glycol, 1,4-cyclohe~ane dlme'chanol, Bisp~enol A, 1,4-b~s (beta-~dro~'cho~y) bl~phenol, }~droquinone, phlorogludnol~ glycerol~
erythritol, pentaerythrltol, meso~erythrltol; 1,7-dihydroxysedoheptulose, sucrose, natur~l mono~a~cha-rides, ~nd th~ like, including ~ny mixtures thereof,.
In the filament forming step (again, with reference to Flg. 1), 4he polymer filamen1: 20 ~8 contacted wlth a primary air stream diracted generally vertic~lly fro~ noz~le~, opanings in ho~zont~lly posltioned tub~ or other me~n~ a8 ~ ave~ the extruder 18. Tho ~ir i~ supplled by ~ compr~ssor bl~wer topera~g.ng up to about 25 p8i) or other ~u~t~bl e 80ul:ce. ~he ~loclty oi~ the air ~tream t~ selected to Rartl~lly dry ~nd attenu~t~ t~le flla~ents to ~ diameter 3ufficl~nltly ~nall ~uch that th~ n'c~ will be further ~ttQnuat~d and will ragm2nt e~lly when con~c~ed wi'eh a ~econdary air ~ream ra~ nozzle 22 ~uppl ied ~ro~ a bl cwer 24 through a ch~ r 26 .. Blower 24 mAy be pro-rided w~th ~ su~cable controller (C~ and fl~w lndlcator ~F). A prim~ry ~ir ~r~am v~locity (mea~ured 6 inche~ rom ~he a~r exit~) o at 1 east abou~ S00 ~e~t per mirlute (f~ .9. r abou~ 500-8,000 fpm, ~ e effective. qhe ~ec:ondary a~ ~empera~ur~
in tunnel 34 may be ~egul~te~ ~y ~team flow ln line 28 to ~ he~t exchanger 30 ln chamber 26. i~ convention~l tempera~:ur~ ~ensor (T~ ~nd controll~r (C) regul~tes th~
temperatuse 'chrough a ~uitable control valve i!snd control v~lY~8 ~ctuator al8 sho~n. Fil~nent~ 20 will h~ve diameter~ of abou'c 5-20 mlcron~ aa a re~alt of the entralr~nent and attenuation by the primary air ~tream.
When cont~cted ~ the high velocity s~condary air ~tream from nozzle 22, ~lowlng at a velociLty of at least ~bout 3,000 feet per ~lnute, e.q~,, about 3,0ûO to 10,000 fee~- per mlnute o~ greater, the filaments 2a are further attentlla'ced ~nd dried, and ~re fragmented in~co flber plece3 3~ whlch are carr~ed by the ~econdary air and v~porlzed water through the houslng or tunnel 34 h~ving an lnl~t adj~cent the nozzl~ ~2 &nd an oppo~ing outlet. ~rh~ flber~ then depo31t on ~ for~lnou~ col-lector ~ur~ace such ~8 ~ 13creen 36 positloned ln the outlet o~ th~ 'cunnel. 5c~een 3~ prefer~bly ~LB ~ounted or po~ltlor,~d alt an ~ngle to the longitud~nal a2i~ of tu~n~l 3~, ~g., about ~5, The t~mperatur~ and humidity ln the ~cunnel 34 a~e 8ensed and regulat~d ~uch th~t th~ wat~ content of ~rsgmen~c~ 32 a~ they collect on ~creen 36 18 i~boU'C 10-15 percent b~ welght. If the f~ber fraç~ment~ are over-drl~d at ~hls polnt the resultlng web will contain void~ and sub3equently crack ~ur~ng the curing ~te~ If the ~ibers ~re too molst the w~b wlll b~come brl tle during th~ ~ub~equent cur-ing. ~h~ secondary a~r ~es~Q in ~dd~on ~o fra~ment-ing ~nd drylng ~he flber~, ~lu9me~ B ~ch~ attenual:lon of the flber~ to ~he desired 5 20 mlcron dla~eter r~nge.
Tunnel 34 1~ dimen~ioned 'co ~'ctain the pro-per ~oi~ture content in th~ 1bers ~8 th~y collect on ~creen 36. ~ nel hou~ing ~bout 12 feet long z~nd havlng lnter~or di~en~lon~ of abou~ 3 feet by 3 feet 18 suitable but oth~r dlmen~ons will Ib~ effeotlve depending upon the water con~c~n~c of the polymer compo-~itlon aR it 1~ formed into iE~l ament~, the h~dro~copl-city of the polymer co3npositlon, ~nd the ext~nt to which the polymer composit~on i~ neu'cralized and c~o~-llnk~d. Pa~s~ge of ~he flbers thxough the tunnel a~
well as t~mperature ~nd hlmlldlty control 18 facili-tated b~ llnlng the tunnel with sultably ~urfaced insul~ting material~ such ~s gla~s fib~r battlng ~ur-f~cod wi~ch a wa~r i~Qper~ious film. Whlle nozzle 22 and 'cunn~l 34 2re ~hown lhorizontally po~i'cloned in Fig. 1" ~r~rticz~l or other positioning m~y al~o b~
prac1:ic~d.
Coll~ction o~ th~ fi~ ~ag~ent~ 34 on the scEe~n 36 1~ f~clll~t~d by a suc~ion g~ner~t~d by blc~ O which pu118 s0condary ~lr ~om tunnal 34 ~L2~5~ 3 PF S0-01-~ 961 -16-~hrouyh ~n exh~uRt chamber 42. The ~uctlon al ~o minl -mize~ cond~nsatlon of water on th~ interior ~all~ of tunnel 34. The dif~erentlal pressure o~ the ~uctlon generated k~ blower 40 i~ regulatad ~y ~ controller (C3 Jsnd ~e~sured by a pre~aure ;en~or (P~ ~cross ~he ~r~en 36. Th~ 6uctioned a1 r i8 exh~usted through stzlck 41 and ~her~ 80 cr~a~ce~ ~ pr~s~ure dlfferent~l to hol d the web ln pl ~c~ on ~he scre~n 36 during lnlti~ ssage in~o ~che oven 38.
Although ~reen 36 laay comprl~ a Pixed sur~ce or a rotatlJ~g dr~n ~eparat~ fro~ tunnel 34, pr~erably ~creen 36 i8 a. for~minous wlre or wlr~
mesh belt as ~h~7wn, whicll ~oves continuously throuqh a curlng oven 38~, Moi~ture ~en~ors ~4 having ~ readout M determine whether the ~ibrous mater~al on th~ wire haæ the requisite moisture content a~ i'c enter~ the overL q~yplcally" the moisture should be le88 than 20 by we$gh~ a8 ~che material enters ~he oven~ to prevent the fiber~ ~ro~ flowlng ~d stickin5~ ~cogether, ~chereby lo~lng ~iber lntegrlty. ~o ~lber ragm~nts now coll~cted on ~ch~ wir~ ln web ~orm ~re mo,intnlned on the wire durlng p1~88a9e through the o~r~n by alr pressur~ ~g~ t one ~ide of th~ wlre and ~uctlon from the oth~r slde g~ner~t~d by air cycled by ~ blow~r ~
fro~ ~L ~uctlon conduit 480 ~he alr 18 tr~n~po~ted ~ia a ~upply ¢ondult- ~9 to a dl~tributlon reglon 50 ~ub-dlvlded lnto ch~nb~rs or menlfolds (not ~hc~wn) po~ltiLonea on one sldo of e~ch o~ the vertlc~l wlre~
~5~C~3 PF SO-Ol~î 961 -17~
~hclwn ln ~lg,. 1~, ~r ~hu~ ~uctloned through one f ace of the wl~ collect:ed in an exhau~ region 51 ad~acen'c ~he oppo~ing ftlc~ of the wir~ ~o compl~te the ~lr iElow cycle. ~ heater 52 de~lrably 18 moun~ed ~ap~t~c~ oP blow~r 46 to h~at ~he air ~tr~am a~
required for curing o} the~ weh ~uitable t~mpera~ure ~ontrols ~T~C~ ~re provlded ~co relate ~i r ~p~ratur~
in th~ ove~ ~o ~pe~d o th~ ~ir~ ~nd oth~r parame~ers for e~ ient cu~ e alr pre~ur~ acros~ wlr~s 36 1 measu~ed b~ ~ ~en~o~ 54. A21~r design of curing ov*rl, and ~1~ supply ~nd ~Jchau~t ~y~m of ~he curing ~a~ren) ~uitable~ iEor ob~alnlng ef~icien~ cure c~n be u~ed. Or~e such deslgn is the oYen and alr dis~rlbution ~ em commerci~lly available from E~on~ycomb Syxt2ms, ~nc., of Blddeford, M~lne.
An oven temperature o~ about 25ûC ~or about 5 minu~es resldence time or abou1: 270~C for ~bout 2.5 minut~ re~ldenGe ~ime provides good cure but lcw~r t~peratures and ls~ng~r residcnce times are ~1BO
suitabl e, ~uch ~8 about 210C: ~o~ about 20 minute~.
~igh~r t~mp2r~cur2s c~n b~ u~ed wlth concomitantly lower re~onanc~ timeEI provlded th~ ~rebs do not di~color,, Generally" ~he oven temperatur~ range may bo ~bou~ 150-275C fo~ re~ld~nc~ 'clm2~ of ~b~ut 35 -0.5 ~nut~.
~pon ~mer gi ng ~ rom the cur i ng o~ en, pr oduct w~b 56 ~lrably 1~ comp~ctod ~ ~ny ~uit~bl~ me~n~
~2~ ()3 ~uch as n~p roll ~ 58 and 60, ~nd 1~ t~n~ported ~o ~
ta k~-up st~ti on 62 wher e i t i c wound on an 1 dl er ~pool 6~ drlven b~ 8pool 66. A ~ension controll er (Y) re~ul~te~ take-up 'cen~ion in a known ~nanner~ If d~s~red~ @mbos~lng roll~ may be u~ed for the cGmpac~on to improve ~h~ integrity ~nd appe~rarlce of th~ ~b by decrea~ins~ ~he vislbll1ty of ~3mall dls-continu~tle~ in the web.
Fig~. 2 and 3 lllustrate one embodiment of a die ~ultable ln for~ing the ilament~ $n ~xtru~lon de~rice 18. With re~Qrenc~ thereto, a die he~d comprl~e~ a dle head cover 68, one or more entry condults 69, and a chamber 70 definlng a manlfold for entsy of polymer syrup through channels 72 ~o nozzle feed chamber 74. The nozzle chamber i~ d~f ined ~y tip body 76 and conununicates wiéh dle holes 78. Fllaments 80 ~re thl3s ex'cruded and en~rained by prlmary air 8tre~!all8 82 and R3 in~ected from openings in supply tube~ 84 and 86. Suitable alr ~upply tube~ may be about 10 inch~s long and have 12 hol~ p~ lnchwh~rein the hol ~ dl~Reter il3 0.020 lncl~. q!ne vel oc~ ~y ~nd Angles o~ lmpingemen's o ~ir stream~ 82 and 83 upon fil~ent 80 ~r~ s~lected rel~tlve ~o the vl~co0i~y of the polyme~ l3yrup ~nd tha location o th~ ~e~ond~ lr ~3tra~uo 8uch that fll~nent8 80 will b~ entralned and att~nllat~d éo the de~ r2d dlam~ter range. A ~uit~ble angl2 og lm~?lngement i8 20 d~gree~ An ~ir knlf~ may b~ u~s~d in plac~ of tub~ 8~. and 86, if d~slr~d.
PF SO-Olol 961 -19 Thu0 b~ prac~clce h~ th~ proce~s of the ln-ventlon, 0uperabsorbent web~ of unlform den~lt~ and h~ving the requl~ sof~ne~ and fl~xib~ll~ ar~
S produced cs~ntlnou~ly and ~~1cien~1y. q~he re~ultlng web le dry to th~ touch and c~la be convenlently :Incsr-por~te~ into varlouR product ~orm~ ln accorda~c~
w~ known pro~edure~.
Th~ following exampl~ ~ill 8~rve~ in cor ~unct~on wlth l?igs. 1-3, as ~urth~r ~llu~t~ation of the lnvention.
~9 L
A polymer Eiyrup i~ pr~p~red, comprlsing ~
409~ polymer ~olid~ ~ol ution of a mal eic an~ydrld~/~ o-butyles~e copolym~r h~vlng a vi~cosity ~verage - molecular wei~ht of about 160,000-170,0ûO ~nd wh~h i8 503 neutgalized with ~od~um lt~droxld~ and erosslinked wlth 7 phr o~ p~oE~rlene ca~bonatQ per (7 par'c~ by weight o~ pzoE~l~ne cArbon~e per 100 parts b~ weight of copolymer).
a! cont~nuou~ web ~ produced bsr bl~wlng f~ber~ ~rag~snt~d ~rom g~llam~nt~ ~xt~ud~d ~ram ~he ~olym~ cup through ~ ai~ t~uch a~ die 18 o~ Flg~. 2 ~ma 3) u~lng prL~ary ~ir ~nd ~cond~ ir a~
descrlb~d ho~¢ingJ,bo~e, to a web ~o~mlng ~cr~en 36 ~2~35~:)3 PF 50~01-1961 -20-coqnprisln~ a wire me~h bel t whlch travel~ through ~
curlng oven 38O Th~ polymer feed pump rat~ (Nichol-~enlth P~np, Model ~IJB-5456-30cc/r~v.~ is e~e'c ~t 3 rpm9 for ~xtru3loJl of polymer at 100 gm/mlnut~ or a~
2.6 gm/minute/hole ~n the die" The belt peed la ~et at 2.S ~et p~ minuteO The r~al ative polymer ~*ed and wire speed are ~tched to give the da~ired web derl l~y. The r~quired ov~n ~cemper~ure 18 ~hea~ set to complet~ly ~ure th~ web ln ;:h~ resldence tlm~ of the w~b ln t~ h~ted zone of the curi~g oven. ~or an oven 63 feet long and a belt of 2.5 fpn, th~ cur~
tlme i~ ~5 mlnut~. For thl~ re~ld~nce time, 195C 1 a Guitable oYen temp~ra~ur~. Once the polymer 1~
flowing ~reely through the die, the belt ~ ovlng, and the proper oven ~eqnper~ture i8 re~ched, the primary alr i8 turned on ~o reach a ve~oc~ .y o~ about 8000 fpm through the hole~ in the ~ir tubes 84 and 86 of Fig. lo Then, the secondary air i8 turned on to at least 7000 ~pm ~or thls feed rate and th~ air i8 heated ~o 125C The temper~ture o~ the secondary air ls ad~u~t~d in chamber 26 to dry 'che w~b ~s lt 1~
formed to 10-15 wt.~ ~oi~ture. ~ econd ry and prlm~ry ~ir are re1aov~d iLn ~he oYen 38 through the belt ~nd eah~u~t~d to the out~ld~ b~ exhaust blcrwer 40 and 8uctlo~a box 42 b~h~nd 'cho b~ One lnch o water : pr~s~u~e ~op across th~ web and bel'c 1~ sufflc1Qrl~c to oxhau~t tlh~ air ~nd d~ it the ~lb~rs ln web fonu on th~ b~lto Th~ exhaust ~an ~peed 1~ lncr~ased until th~ pr~s~ure drop 1~ achieved. ~h~ w~b travel~
~2~5~03 P~ 5û-~1 1 9~ 1 -21-through the oven on th~ movlng belt and 1~ removed ~
the exi~where lt can be embo~sedor simply rolledup.
A web produced a8 descr$bed has a den 1 y o~ 105 gJm2, absorb~ ~Ø2 g/g o:E 0.9% brln~ ~olutlon and re aln~
26.3 g/g of the br~n~ ~ol utîon under a pr~esure of 0.5 psi~ The wa~er~welled web i8 dry to th~ touch~, ~9 ~
Sub3~ant~ally ~ d~crib~d ln ~xample 1 l~u~c u~ing ~ polym~r fo~ul~tion dierins3 from th~t o ~xample 1 by sub~tltu~cion o~ p~ntaerythrltol and bu-t~nediol for proE~ylen~ c~rbona~e ln amounts o~ 8 phr and 2 phr, respectlv~ly, and increa~ing ~he ~elt ~p~ed to 2.8 fpm, ~ fibrous web 1~ produc~ he cure re~ldence t~me 1~ 22.5 minutes~, The oven temper~ture for thi formulation nnd resldence tlme i8 175C and the ~econdAry ~lr tempe~ture i8 lOO"C. The collector pres~ure drop on the belt 18 inc~ea~ed -o 2.0 inches ~ o~ water to dr~w th~ ~bers to the belt more evenly.
The web p~oduced ha~ a derlsi~ o~ 83 gJm2d zlbsorbs 4808 g/g o~ a 0.9~8 brine solution and retains 28D9 g~g of the brln~ ~ol ution und2~ a pr~ur~ o~ 0.5 psl. The solubllity o the polymer 18 1~6~o5
Claims (23)
1. A process for producing a nonwoven fibrous web from an aqueous solution of a polymer composition which is water insoluble and superab-sorbent upon curing, which comprises:
(a) forming the polymer solution into water soluble filaments, (b) contacting the filaments with a primary air stream having a velocity effective to partially attenuate and to partially dry the filaments, (c) contacting the filaments in a fiber-forming zone with a secondary air stream having a velocity effective to further attenuate and to fragment the filaments into fibers, to further dry the fibers and to transport the fibers to a web-forming zone, (d) collecting the fibers in reticulated web-form in the web-forming zone, and (e) curing the web in a curing zone;
wherein the temperature and air stream velo-cities are controlled with respect to ambient humidity and water content of the fiber during fiber and web formation such that during collection the fibers remain substantially non-sticking and cure in the curing step to a soft, integral web.
(a) forming the polymer solution into water soluble filaments, (b) contacting the filaments with a primary air stream having a velocity effective to partially attenuate and to partially dry the filaments, (c) contacting the filaments in a fiber-forming zone with a secondary air stream having a velocity effective to further attenuate and to fragment the filaments into fibers, to further dry the fibers and to transport the fibers to a web-forming zone, (d) collecting the fibers in reticulated web-form in the web-forming zone, and (e) curing the web in a curing zone;
wherein the temperature and air stream velo-cities are controlled with respect to ambient humidity and water content of the fiber during fiber and web formation such that during collection the fibers remain substantially non-sticking and cure in the curing step to a soft, integral web.
2. The process of claim 1 wherein the fibers formed from the polymer solution are collected on a forming wire and the forming wire carrying the fibers moves continuously through the curing zone.
3. The process of claim 1 including (F) compacting the cured web.
4. The process of claim 3 wherein the com-pacting includes embossing the web.
5.The process of claim 1 wherein the tem-perature and air stream velocities are controlled in the fiber-forming and web-forming zones whereby the moisture content of the fibers prior to curing is less than 20% by weight.
6.The process of claim 1 wherein the pri-mary air stream entrains and transports the filaments to the fiber forming zone.
7. The process of claim 1 wherein the velo-city of the primary air is at least about 500 fpm and the velocity of the secondary air is at least about 3000 fpm.
8. The process of claim 1 wherein the poly-mer solution comprises about 25 to 60% polymer solids and the polymer composition comprises a blend of (1) a copolymer of at least one alpha, beta-unsaturated carboxylic monomer and at least one monomer copoly-merizable therewith and (2) a crosslinking agent wherein the crosslinking functionality comprises hydroxyl or heterocyclic carbonate groups.
9. The process of claim 8 wherein the co-polymer comprises about 20-80 weight % pendant car-boxylic acid groups and about 80-20 weight % pendant carboxylate groups.
10. The process of claim 8 wherein the co-polymer is a copolymer of maleic anhydride and at least one of styrene and isobutylene, and the cross-linking agent is propylene carbonate, ethylene glycol, propylene glycol, 1,4-butane diol, diethylene glycol.
glycerol, pentaerythritol, meso-erythritol or any mixture thereof.
glycerol, pentaerythritol, meso-erythritol or any mixture thereof.
11. The process of claim 1 wherein the poly-mer solution comprises about 25 to 60% polymer solids, the polymer composition comprises a blend of (1) a copolymer of at least one alpha, beta-unsaturated carboxylic monomer and at least one monomer copoly-merizable therewith, and (2) a crosslinking agent, wherein the crosslinking functionality comprises hydroxyl or heterocyclic carbonate groups, and the process conditions are as follows:
primary air velocity: about 500 to 8000 fpm;
secondary air velocity: at least about 3000 fpm;
secondary air temperature: about 25 to 140°C
temperature of curing zone: about 150 to 275°C
residence time of web in curing zone: about 0.5 to 35 minutes
primary air velocity: about 500 to 8000 fpm;
secondary air velocity: at least about 3000 fpm;
secondary air temperature: about 25 to 140°C
temperature of curing zone: about 150 to 275°C
residence time of web in curing zone: about 0.5 to 35 minutes
12. The process of claim 1 wherein the poly-mer solution comprises about 35 to 55% polymer solids, the polymer composition comprises a blend of (1) a partially neutralized copolymer of maleix anhydride and at least one of styrene and isobutylene, and (2) a crosslinking amount of propylene carbonate, ethylene glycol, propylene glycol, 1,4-butane diol, diethylene glycol, glycerol, pentaerythritol, meso-erythritol or any mixture thereof, and the process conditions are as follows:
primary air velocity: about 500 to 8000 fpm;
secondary air velocity: at least about 3000 fpm;
secondary air temperature: about 25 to 140°C
temperature of curing zone: about 150 to 270°C
residence time of web in curing zone: about 0.5 to 35 minutes.
primary air velocity: about 500 to 8000 fpm;
secondary air velocity: at least about 3000 fpm;
secondary air temperature: about 25 to 140°C
temperature of curing zone: about 150 to 270°C
residence time of web in curing zone: about 0.5 to 35 minutes.
13. The nonwoven web produced by the process of claim 1.
14. The nonwoven web produced by the process of claim 8.
15. The nonwoven web produced by the process of claim 10.
16. The nonwoven web produced by the process of claim 12.
17. Nonwoven fibrous web producing appara-tus, comprising, in combination:
(a) means for forming an aqueous poly-mer solution into filaments, (b) first air supply means positioned to direct an air stream upon and to partially attenuate and to partially dry the filaments (c) a housing having opposing inlet and outlet means, (d) second air supply means positioned to direct an air stream upon the filaments for further attenuation and for fragmentation thereof, and to further dry and carry the fragments through the inlet and outlet of the housing, (e) foraminous surface at the outlet of the housing for collecting the fragments in web form, (f) suction means adjacent to the foraminous surface positioned to entrain the fragments on the foraminous surface, and (g) means for curing the web on the surface.
(a) means for forming an aqueous poly-mer solution into filaments, (b) first air supply means positioned to direct an air stream upon and to partially attenuate and to partially dry the filaments (c) a housing having opposing inlet and outlet means, (d) second air supply means positioned to direct an air stream upon the filaments for further attenuation and for fragmentation thereof, and to further dry and carry the fragments through the inlet and outlet of the housing, (e) foraminous surface at the outlet of the housing for collecting the fragments in web form, (f) suction means adjacent to the foraminous surface positioned to entrain the fragments on the foraminous surface, and (g) means for curing the web on the surface.
18. Apparatus as in claim 17 wherein the second air supply means is positioned substantially normal to the path of the attenuated filaments, and including temperature and humidity control means in the housing.
19. Apparatus as in claim 17 wherein the foraminous surface comprises a moving wire belt adapted to carry the web, and the curing means comprises an oven chamber adapted for passage therethrough of the belt carrying the web, the apparatus further including web takeup means.
20. Apparatus as in claim 17 wherein the filament forming means includes a die having a plura-lity of die holes, and the first air supply means comprises air tubes positioned adjacent the die holes.
21. Apparatus as in claim 19 including air exhaust means to effect an air pressure differential to hold the web in place on the belt during initial passage through the oven chamber and to exhaust air from the secondary air supply means.
22. Apparatus as in claim 17 further inclu-ding web compacting means positioned after the curing means.
23. Apparatus as in claim 17 further inclu-ding web takeup means and web compacting means posi-tioned between the curing means and the web compacting means, wherein the foraminous surface comprises a mov-ing wire belt adapted to carry the web, and wherein the curing means comprises an oven chamber adapted for passage therethrough of the belt carrying the web, the apparatus further including a third air supply means and air exhaust means connected to the third air supply means to thereby effect an air pressure differential to hold the web in place on the belt during passage through the oven chamber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/079,312 | 1987-07-29 | ||
| US07/079,312 US4855179A (en) | 1987-07-29 | 1987-07-29 | Production of nonwoven fibrous articles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1295103C true CA1295103C (en) | 1992-02-04 |
Family
ID=22149739
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000567802A Expired - Lifetime CA1295103C (en) | 1987-07-29 | 1988-05-26 | Production of non-woven fibrous articles |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4855179A (en) |
| EP (1) | EP0301804A3 (en) |
| JP (1) | JPS6433258A (en) |
| CA (1) | CA1295103C (en) |
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Also Published As
| Publication number | Publication date |
|---|---|
| US4855179A (en) | 1989-08-08 |
| EP0301804A3 (en) | 1990-05-09 |
| EP0301804A2 (en) | 1989-02-01 |
| JPS6433258A (en) | 1989-02-03 |
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