[1]United States Patent Office 321,0,11292 P a t e n t e d A u g . 2 0 , 1 9 6 3 3,101 ,292 ME THODS FOR MAKING BONDED NONWOVEN FIB ROUS PRODUCTS AND THE PRODUCTS OB TAINED 5 Benj amin B. Kine, Elkins Park, and Nathaniel A. Matlin, Levi ttown, Pa., assignors to Rohm & Haas Company, Phila delphia, Pa., a corporation of Delaware NoD rawing. FiledMay2O,l960,Ser.No.30,448 9 Claims. (Cl. 161-227) 10 This invention relates to @bonded non-woven fibrous or filam ent6us products having a c@rded fibei structure or com prisijag fibrous mats in wliich the fibers or Maments are distributed haphazardly or in random array. The inventi on also relates to methods for producing the bonded 15 nonwoven fibrous products or shaped articles therefrom. The bonded non-woven fibrous products are useful in the prod uction of articles of either flat or three-dimensional shap e, such as insulating material and the!Eke as wi.-U be desc ribed more particularly hereinafter. This application 20 is a continuation-in-paxt of our copending application Seri al No. 603,83;3, filed August 1113, 1956, now abandone d. Her e,in,after, the expression "random array" is intended to include the array of fibers in a carded web wherein 25 parti al orientation is frequent-ly present as well as other arra ys in wbich the fibers are in a completely haphazard distn butional relationship. Her etofore, binders of natural rubber latex and aqueous dispersions of synthetic rubbers, such as butadiene 30 copo lyrnerized with styrene, acrylon itrile, and so on have bee n suggested as binders for bonding the fibers in nonwoven fabric structures; but these materials have vai@ious disa dvantages, among which is the tendency to impart aii offwhite @appearance or cast to the bonded products, and 35 this tendency is so strong that it is difficult to overcome eve n by the use of optical bleaches pr by, the 'use of white pigm ents, such as titanium dioxide. Also, the synthetic rubb ers are unsatisfactory for maki:ng products It:hat are 6xpo sed to sunlight,. such as ou I 40 ter weanng apparel, becaus e of lack of resistanceto ultr,,aviolet radiation. These rubb ery binders also produce a rubbery hand which,APpear s to be the result of a complete suppression of the fibro us character insofar,,as the feel of the product is conc erned. Vvhen binders of polyvinyl acetat@,s, -chlo45 rides , or their copolymers are used, t-he hand becomes pape ry, by which is melant that the product 7ha's a crisi@ brittl e hand and, conveys -the impression of th-inness and fragi li@y. It also produces a noise on crumpling th,at is ro typic al oi papers. The application of thermoplastic polymers such -as simple es-ters. of acrylic or methaerylic acid prod uces,pr'oducts in which the binder remains perinanentl y thermoplastic with consequent tendency to chang' e res. The SiMP16 Avhen subjected to excessive temperatu 55 acrylic and methacrylic acid esters are also characterized by relatively poor adhesion to hyorophobic @typ.sof 'ilbers such as nylon, vinyl reslin fibers, celluloe,e 6s'ters and, suc)K polyesters as polyethylen(-,_il.yc6l terephthalate. 'Furthermore, many of the binders' -heretofore, employed, includ- 60 ing the,aqueous dispersions of rubber, syi@thetic rubbe- , rs, and acrylic esters, cannot be washe I d, scoured, or drycleaned. Also, these bind&rs have a strong,tehde , ncy to migr,ate to the surfaces of the:@fibrous pioducts dur' . mg .drying of the products to which:@the d ispersions:have - been 65 appliied. Uni,ted States Patent 2,82-3,142 , disclo ses the application of saft acrylate addition @polymers with certain @thermosetting condensates to produce bonded non-wo@en fabthe soft hand and draping @quality are both lost and the p,roduct, though the fibers thereof are still bonded by the thermosetting, condensate, acquires a -harsh hand and @does not drape in a @desirable fashion. It is an@ object of the present invention to provide fibrous products made with a binder which:can be applied by way of an aqt@eous system without tb-- disadvantages mentioned above that -ate characteristic of previo@SIY applied!aqueousbindersystems. Afurtherobjectoi@the invention is to provide ia bonded fibrous product of nonwoven character in which the binder, whether it consists of an addition polymer @lone or df a mixture thereof with a thermosetting resin-forming condensate, is adapted to be converted to an infustible and insoluble condition as by heating with of withoilt -the presence of a siiltable catalyst as will be. pointed out more particu-jarly hereinafter. It is @i fatther object of the present invention to produce bonded fibrous products of non-woven character from fibers which are incapable of felting, wh6ther of natural or synthetic origin, and,especially those which, :unldke wool, have relatively smooth surfaces extend'mg lonkitudinally of the fibers, and b6cause of these surface characteristics are incapable of being converted anto a felted product -by normal felting 6perations. A further object of the invention @is to provide bond4@d fibrou products of nonwoven ch-aracter wherein the binder m4y 'be s stantially uniformly distribtited through;the I b6dy of the @tructure and has reducedtendency to mligrate preferentially to the surfaces of the strii@t@re. Other objects and advantages of the invention will be apparerit from the description thereof hereinafter. The:bonded fibrous products of the invent@ion comprise a binder deri-ved from an essentially water-insoluble linear polymer containing dicyandiamide gropps wmch in _the fineil bonded products are iapparently cross-linked t.o an insoluble condition. Tihe versatuity of the binder used in the present invention is such as:to be readily adapted to various methods of production of the fibrous products. The bonchng of@ the fibers is effected with a cle@ar, substallt., ally @,olorless binder which has good adhe@sdi)n t6 all sbrts of fibers and filanients !and even to those of siliceous character which, in the past, have b.een difficult -to handle because of the difficulty of find'mg colorless -binder materials which are adequately adhesive toward the siliceous materid such -as glass. The binders of the present !invention are also substantially free of @discol6ration when subj&cted to elevated temperatures, such @as those used for drying,@fusirig, or curingThe binder of the present invention contains a pliurality Of dicyandiamide grolips by which it is adapted to be insolubilized and rendered infusibl-e on heating with or without suitable oatalysts which are ge-ne-rary of acidic character. Hence,thecuredorbakedfibrousprodu@,tprovides improved iresi@tance to laundering, dry-,cleaning and spot@ti ng, to various chemicals, andto heat as com@ared to the aqueous systems,,such;as rubber latex or @aqueous dispersions of synthetic rubbers or ;acrylic or vinyl esters heretofore applied. The bonded fibrous products of the' presen-t invent-i@on can be heated to ;a much higher temperature than t,hose of the prior art using the binders mentioned @above w'ithout suffering discoloration, increase in stiffness or deleterious docor@iposition. They are charae,terized by @ excellent resistance to irgning in which operation they are not subject to tackinegs as would be true 6f the @thermoplasti-@s heretbfore u-sed. The dicyandianilde groups apparent-ly ialso provide a greater versatil . ity 'Of hesion in that the binders of the present invention are characterized not onjy withgood adhesion@t I o@h ydrophilic fibers lik4D cotton, regenerated cellulose rayons -and the like rics wluch initially have a soft hand and desir@able drap- 7( but they ai@eaiso characterlized bv excellon-t @adhesldn -to hy@. ing quality. However, on dry-cleaning the product, the drophobic types of fibers, su@h-as the nylons and especial@; addition polymer ds gradually @removed. Consequently ly the polyamide types, th@ yi-pyl resins such as copolymers
[2]of -vinyl chloride witli vinyl laedtate or with acrylopitrile, polymers of 70 to 90% acrylonitrile with other monomers @.uc@h as vinyl chloride, vinyl acetate, any of the vinyl pyridines such ;as 2-vinyl pyridine or mixtures of such auxiliary: comonomers, polyesters qllch as poly(ethylene 5 glycol -terepli@thalate), and collulose esters such,ascellulose aceta,te, cellulc)se acetate propionate, @cellulose acetate butyrate, and so on. Be-lause of the cha-racteristic adhesion of the binder of the present invention to both hydrophilic and hydrophobic types of fibers, the fibrotis ptod10 ucts are characterized by excellent resistance to - "pilling" and abrasion. The binder of the present invention is adapted to be dried :and then cured to insoluble and infusible condition so tha-t the bonds cannot be - disturbed even under severe @conditions of heat. TI-le fibrous prod15 ucts @using the binder of tiie prese-.lt invention have the advantage also that they can be e@nbossed durably in wet conditior. or during the first drying but before complete drying. This is @evidencp-d by the fact thaf if -the dryin.- is effected -on a 'snction screen through which the excess 20 water is drained from the fibrous product, the pattern of the screen is permanently impatted to one face of the prodtict jand even,,calendering under normal procedures and temperatures do,,s not destroy this patte@rn effect. NVWle the binder may be preferentially applied, if desired, 25 to por-tions of the fibrous product, su.-h as one or both of the faces thereoif, it is characteristig of the binder of -the present invention that if such preferential treatment is not desired, substantially unffor-m distribution may be obtained because of the reduced tendency of the binder 30 afte,r initial Fdistribution throughout the body of the fibrous product to m@.grate to the surfaces thereof during drying. The binder of @the 'present invention may also coritain, besides the dicyandiamide-co@ntaining polymer, thermosetting aminoplast condensates si,-rh as of urea or 35 melamine or the like @with formaldehyde and the catalyst used for accelerating the condensation of the aminoplast to insolnble and infusible condition ser-ves @s irnultaneously and/or concurrently for the curing of the dicyandiamidec<)ntaiiiin.- pol37mer to -the insoluble and in-fusible condi4.0 ,tion. the cured :or i@isolubilized binders are -unaffected by water or @organic solv,ents, such as styrene, even at nioldin@g temperatures, whereby the bonded fibrous products are adapted to be used as molding preforn-is or molding inserts 45 for the production of molded afticles f@rom various @thermosetting resisns as will be pointed out in more detail hereinafter. The, binders are also free of cold flow and are resistant to ffow at elevated t-emperatures, whereby shifting of the fibers or filaments in the bonded products is 50 substantially co@r@ipletely prevented even at elevated temperatu,res d@uring subsequent molding with such products being used as reinforcing inserts or preforms. In accordance with the present invention, ja fibrous prod- 55 uct, the fibers of which comprise a predominant propot,tion or consist en@tirely of fibers which are incapable of f,-Iting,_ is inipre,,-iiated with an aqueous dispersion of a water-insoluble linear polymer iof monoethylenically unsaturated monomeric units comprising 3 to 50% by weight , of at leastone monomeric cornpound having the structure 60 of Formula 1: CH,--C(R)CON,HC( I =NH)NHCN (1) where R is selected from the group consisting of hydrogen and methyl. 65 T-he molecular weight of the polymers should be from -abo@at 100,000 to about 10 million. Generally, - water-insoluble copolymer co-@itairilng units of which from 3 to 20 % by weight contain the dicyandiamide groups are mosi prac,tical. It is prcferred to employ copolymers contain70 ing,f,rom 3% to about 209o of units containing - dicyandiamide igroups when soft, flexible produ6ts are desired Ho-wev@r, polymers containing a larger proportion of units baving dicyandimaidegroups -up to 50,Yo are useful - @vhen a !7eIatively stiff product is dosired, @or when soft products 75 are desired and the comonomers contain large alkyl or alkylene -groups totalling 8 or more carbon atoms. The aqueous disp,-rsion @,is preferably obtained by emulsion polymerization in the presence of an emulsifying agent 0-f at least one monomer of Formula I above. The preperation of aqueous dispersionsof polymers of these dicyandiainide monomers is disclosed in United States Patent 2,828,2Z2. The subject mat-ter of this patent wljich deals with the, preparation of aqticous dispersions of homopolymers and!copolymers containir-?g at least 3% byweight of an unsatu@,rated dicyandiamide monomer is incorporated herein by reference. The fibers are present in the form of a so-caued "nonwoven" mat in which they are haphazardly distributed, or the Tnat may be formed by carding when the fibers are of such a character, -by virtue of lengta and flexibility, as to be anienable to the carding operation. r ers ju@te, sisal, @ramie, herrip, and cotton may be used, as well as man@y artificial fibers or filaments includin.- rayon, those of ceIlulose e;sters such as cellulose acetate, vinyl resin fibers such as those of polyvinyl chloride, copolymers of vinyl ch-loride with vinyl acet@ate, vinylidene chloride or acrylonitrile containing a -major proportion of vinyl chloride in the polymeir molecule, polyacrylonitrile and copolymers of acrylonitrile,,with vinyl ebioride, vinyl acetate, mothacrylon,.trile, vinyl pyridine, or with nlixtures of such comonomers and containing a major proportion from 75 to 95% of acrylonitrile in the copolymer molecule; also condensation polymers such as polyamides of nylon type,- polyesters such @as ethylene -glycol-terephthalate polymers and -the like. The thin web or ffeece obtained from a single card may be -t@reated in adeordance withthe presen-t invention, but gpnerally it is necesary and desirable to superpose a plurality of such webs to build up the mat to sufficient thicl(nass forthe end use intended particularly in the making of heatinsulation. In building up suoh a Tnat,,al@ter I nate layers of carded webs .may be disposed with - their fiber orien-tation directions disposed at 60' or 90' angles with res.pect to intervetiing layers. Mats may also be formed by the deposition iDf fibers, either natural or artificial, from, an air stream. Thus, continuous filaments rnay be fed to a cutter or breaker which discliarges the fibers into the discharge side of a @blower. S-ui-table conduits are provided to gu@ide the flbers to a collecting screen or air-pervious structilre, for collecting the fibers inthe -form. desired. The screen may be in -the form of an endless traveling belt passing through the lower portion of a tower into t@he upper portion of which the blown fibers are introduced bythe conduit work. A suction boxmay be disposed beneath the upper course of the traveling screen @to assist in the deposition of -the fibers thereon. Instead of having a traveling flat sereen, a stationary for-ined srreen may be used. For example, it may take the form of a hat-shaped cone such @as that used in the felt hat-making industry. Alternatively, it inay have iany other form suitable to produce the desired shape of the fibr6us product, suchas a rectangular tray. Again, suction may be applied beneath the -screen t<) assist deposition Df the fibers -thereon. Tbe fibers and fflaments may be formed by direct spraying from a solution or molten mass, thereof. This is a convention,al procedure for the formation of glass fibers or mineral wool fibers as well as: those of nylon or of thermoplastic materials, such as vinyl resins of the type nientioned heteiniabove, iadapted to be dissolved in a suitable solvent, such as -acetone or dimethylformamide, or to be melted. . Tbe solution,or melt is, of course, diregted to suitable nozzles or jet-forming orifices and a high pressure fluid stream, such as of cold or hot air or of inert gases such as nitrogen or even of steam@, is directed against the stream or streams of filatnent-forminmaterial to disrupt them and coagulate -them, as ers in the vicinity of the orifices. Electr6static spinning methods may also be employed for this purpose. As in the case of the use of blowers, the disrupted and dispersed fibers
[3]5 may,be directed to the -top of @a settling tower and be iallowed to settle, witli @tht-, ia@ld of suetion devices, upon a suitable traveling or stationaiy scieen at the bottom of the tower. T,his ptocedure is adaptable to, the produetion of fibers of siliceous materials such as: glass or M'Meral 5 wool as well as tothermoplastic resin fibers mentioned above. Another procedure may involve,the extrusion Df con,tinuou,s filaments, either from solutions, of @the fllamentfornu,ng material or from molten masses thereof, and the 1 0 cutting or break-in.- of the ffiatnents to fibers of ia predetern-iined -length which .rnay be fed to a @hoppfr at the -top @of a settling tower into which they may be disc-har-ged ,,by conven-tionat feeding devices, and at the bo-ttom of whic,h a traveling or stationary screen may be deposited 1,5 for cdllmtion lof the fibers. T-he fibers and filamentst@hat may be u-sed in the present invention may be natura, or @artificial as stated ab<)ve. T@he selection of Lbe particular material of which the fiber is madefrequen'dy depends upon the use int--nded Of 20 the product. For example, sfliceoiis flb--rs are extreinely valli,able in t@heproduction of molded articles because of ,the exiceptional strcngth obtained by their use' However, when the bo@ded fibrol-is produots,are used for futration purposes, fibers of certain resins may be preferred to pro- 25 v@ide resistance to attack by @acids or alka@lies that ma-y be pre,sent in the liquids to be filtered. T@hus, polymers containing a high percentage of arrylonitrile or of vinyl chloride or even of sugh highly halogenated resins as polytetrafluoro--thylene or poly(ohlorotrifluoroethylene) 30 may ibe more useful in suoh cases. For cer-tain purposes, it,may be desirable to form the fibrous products from a niixtuxe of fibers of diff-.rent types. An example iis the use of a mixture of thermoplastic fibers of po@tentially adhesive -ch@aracter Nvith ot@har fibers which lack such poten35 tially adhesive @character. A fibrous produot co@mprising suoh a mixture may be heated to the - appropria@te temperature to render the potentially adhesive fibers tacky to effect binding of the fibers in the product by this procedure as Nvell as by the binders of the present invention. , @ 40 T,he binder of the present invention is applied in the form iof an ;aqueous dispersion which may be produced by the emulsionpolymerization of monomers containin" . dicyandiamide groups with other monoet-hylenirally unsaturated comonomers. The comonamers may be se45 lectedtoprovidevarious,propertiesin,thebinder. Thus, they,may provide a soft,and flexible binder or they may provide -a hard iand stiff binder which impiarts correspondi@ng stiffness to the bonded fibrous product. Siirprising-ly, dispersions of copolymers having Ti values,of 50' C. and .50 over can be effectively employed to form coherent bonded "non-woven" fa-brir_s, even though these dispersions ordinarily do not form continuous fil@ms when applied @to textile -fabr-ics and dried at temperatures ab@ove t@heir respective Ti values. Useful comonomers which tend to yield soft fiexible polymers when copoly@merized wi@Lh o-neof the dic@yandiamide monomers mentioned @above are -thoso whioh yield solid polymers which have a T, belciw 15' to 20i' C. The T, value referred to is the transi@tion - temperature or in- r) 0 flection temperature which is foutid by plotting 'the modulus of ri.-idity against temperature. A convenient method for determining moduliis; of rigidity and t-ansition : temperature is des@ribed by 1. @Willivm, on, British Plas, ties 23, 87-90, 102 (September 1950). The Ti vnlue 65 here lised is that deter-mmed,at 300 kg./CM.2. The polymerizable, netitral como-nomers which form soft, solid polymers in the presence Df free radical cata.- lysts include -any primary and secondary alkyl acrylate, even with alkyl subs@tituents up to eigh-teen or more c@u70 bon atoms, -Drimary or seco-ndar3r z@lkyl mothacrylates with alkyl substituents of five to eighteen or more carbon atoms, or other monovinylidene co@mpou-nds as defined above wh@ich are @polymerizable with free radical catalysts 6 satupated monooarboxylic esters,of,over-two,car-bonatoms. The preferred monovinylidene compolunds are -.the stated a6rylates and meth.,acrylates andof these the most practical es@ters are -those -with alkyl groups of n@otover 12,carb.on atoms. The preferred monomers, wliioh bythemselves yield soft . @ polymers, may be summiarized by-,the formula CH2=C-COOR' where R' is hydrogen or the methyl group, and Rx represorits, when R' is mothyl, a primary or,secondary alkyl group of 5 to 1 8 carbon atoms, or, when R' is -hydr(?gen, - an alkyl grou-p of not over 18 carbon atoms, 4Dr b6tter, of two to 12 carbon atoms. Typical comp!ounds coming within -t@he,above deftnition are methyl acryla'te, ethyl iacry-late, propyl acrylate, isopropyl arrylate, butyl acrylate, isobutyl - acrylat@, secbutyl acrylate,!amyl @acrylate, isoamyl acrylate, b,@xyl ac,.rylate, 2-ethylhexyl iacrylate, octyl facrylate, 3,515-trimethylhexyl acrylate, decyl -acrylate, dodecyl.acrylate, ce@yl ac@ rylate, iort-adecyl acrylate, octadecen@yl iacrylate, namyl methacrylate, sec-amyl methaorylate, hexyl met@,acryl-ate, 2-ethylibutyl methaorylate, octyl methacrylate, 3,5,5-tnmethylhexyl methacrylate, idecyl methacrylate, dodecyl methlacrylate, octadecyl methacrylate, and butoxyethyl acrylate or meth@arryl@ate. As polymerizable monovinylidene monomers, whichby themselves form hard polymers, there may bze, used alkyl metl@acrylates having alkyl groups iof not iover four icarbon atomis,,aaso tert-amyl meth@acry-late, tert-butylor tert-.@my@ agryl@ate, cyclohexyl or -benzyl iacrylate or meth,acryjate, acrytonitril--,,or methacrylonitrile, @these constitatino:,, a preferred group of the, coniplounds formi@ng hard polymors. StyTene, vinyl chloride, chlor@ostyrene, vinyl acetate, a'c,rylamide, methacrylatnide, land p-methylstyrene also-form hard p@olymers. P,,rofer-red monomers, which by themsielves form -hard polymers, may ble summazized by the fotmula CH2=c-x wherein R' is hydrogen or the methyl group iand wherein X repre@sents one bf the igroups -CN, phenyl, methylpbeayl, iand esterfo@rming g@roups, -COOR", wherein R" is cyclohexyl lor, when R! is hydrogen, ia tert-ailkyl @group of four to -five carbon atoms, or, when R' is m--thyl, ah alkyl -group of one to fout carb on atoms. Some typical examples of thesp, have a-ir-eady been n@arned. Other spepifir-,compounds iare methyl methacrylate, ethyl methacrylate, propyl met@hacrylate, isopropyl methiacrylate, butyl methacrylate, sec@butylmethacrylate, tand tort-butyl methacryllate. It is frequently desirable to ropolymerize the dicy andiamide-containing monomer witha mixtuxe of two or lmore different comonomers, one or more of which are select ed from the hard -category, just mentioned iand- another of whioh is -selected from the soft category. An examp-le (>f this would be la,copolymer of 8 to 55% iet@hyl acryjate, 44 to 90% of methyl mothaerylate, and from about 3 -to about 6%, of met-haorylyl dicyan-dianlide. The p6lymers used,as bindets,of the pres@ni invention may be graft or block icopcdymers wh6roin one, I or more but not all of the monomer& are first polymerized andthen one or more @other monomers are edpolymerized with the first p,olymerobtained. Thus, a dicyandiamidecontaining monomer niay first b-@ homopolyme.rized or @00polymerized with one or more, ibut less,-than all, of -the comonomers to be intro,duced into-,the ultimeite copolyme@, and then the last monomer,or monomers ar@e,added tD t-he system and copolymerized ior grafted on to the first homopolymer or colunm formed. Tho same procedure may be used in Teverse order to igra;ft the, dicyandiamide-containing units on to ia previouslyformed homo er c ,poilym@ r to for@m soft, solid polymers, including vinyl esters of 75 copc)lyme@r of othor monomericunits. Again, a plurality
[4]7 of nionom-@ric units may be introduced in - succcssion and the dicyandiamide@group-containingmonomer may be introduced a@t the beginnin@g, at any intermediat-- sta,@e, or at the end, as desired. The copiolymers of the present invention have a Ti of 5 a,bout 30' C. or lower. These set on dryin,@ at robm temperature to bind the fibers with a soft flexible binder brid.aing the fi-bers attheirpoints of interseztion or interr-rossing with a firm grip. Their flexibility adapts ithe fibrous pr<)duct to be readily confortmed to shapod con- 10 tours which may be of value in,-.ases where an insulating produr-t ior mat is desired to ibe bent into the shape of a str,ucture to be covered there;with ias in the wrapping of ia pipe:or cyadrioal vessel. Such wrapping can be effected wit,hout extensive rupture,olf theb!onds between the fibets 1,5 and,,withiout !excessivo compacting of the mat, i@,ft'oh there,by largaly retains its bulky chatacter with numerous sinall air-spaces and high heat-insulating value iandis subsequent,ly rendered permianent by the baking operation. T,he dispersionsadapted to be used,as the binder-apply- 20 in,g medium of the present invention are most advant,a.-e,ousi@y prepated by emulsifying with,a dispersinig a.-ent and polymerizing, preferably underthe influence of a fre--- radical catalyst, a mixture of monomers uf which 3 to 50% is one of the dicyandiamide-co-iltain',.n, monomers 25 ,above. Anion-ic, cationic,,and non-ionic emulsifiers,or dispe@rsin@ agent@s may be used. Less advantageously, waterinsoluble polymers ;complising 3 to 50% of idicyandiarnide-containing nionomcric. units produced in any other 30 way may be dispersed in waterby means of suitable disp@ets-ing agents. T-he dispersions may contain ias little as 1% 'and as much ias 60% of the re-sinous 'Copolymer on a weight basis. It is, however, morepractical-hence preforred- 35 to iproduce dispersions which contain about 30 to 50% resin-s,olids. Generally, the,dispetsion ds diluted to I to 3 5 %, and prefer@ably 2 to 3 0 %, re-sin content at which it is readily,adapted to be applied @as by spraying, dippin,,, printi,ng, or by transfer rolls. 40 T,he binder of the present invention i@n the form of a dispersion may be applied to the dry fibers after the - formation or depositionof the web @,or @mat so as to penetratc, pard,a,lly into or coinpletely through the intetior of the fi,brous products. Alternatively, the binder dispersion d,5 may be @applied to the fibers as they fad@l through the settling chamber to their po,int @of ideposition. This is advanta.-eo,usly obtained by spraying t@he binder dispersion into the settling ch@amber at some intermediate point bet,w,een the top and the bottom thereof. By so spiraying 50 the fibers as they descend 'Lo thdpoint,of collection, it is possible to effect a thotough distxibution @of the binder among,the fibers before they @are corected into the product. in the production 4of certain fibrous products Wherein la h,ot @molton mass of -a polymer, isuch as nylon or a -fused 55 siliceous mass or glass, is disraptedby jets of heated iair or steam, the binder dispersion maybe sprayed oT dusted directly on the fibers whi@le stul hot,and very ishortlybefore t,hei,r,deposition so that quickly after deposition the binder is set and bonds the fibers in proper relationshi-p. Prefer- 60 ably, -however, application iof the binder dispersion to the ,R,brous product is made at room temperature to facilitate cleaning @of the apparatus associated with the application of the binder dispersion, The binder fdispersion may be applied to oneor both sutfaces of the fi-brous product @or it 65 may be distributed throu.-h the intorior as well. The binder of the present invention may be applied in conjunction with other bind--rs. For example, another type of binder, such as -glue or resin-fonning condensates, es-pecially aininoplasts such as urea-formaidehyde' mel70 amine-formaldehyde and the like, may be applied either to the interior or to the external surfaces of the fibrous products. Similarly, the use of potentially adhesive plied to the extemal surfaces or to the interior of such products. Similarly, the use of potentially, aaesive@ 75 3,101,2 92 fl,'bers withiii the fibrous product may also be resorted to in coniunction, with the tise of a binder of the present invenftion. The aql,.eous @d@ispersion may also contain dissolved therein a water-soluble thermosetting conderisation product, especially the aminoplasts, n@ainely the low molecular vieight or monomeric reaction preducts of an aldehyde, and especially formaldehyde with urea, thiourea, biuret, or other homologues or deri-vat@i-ves thereof, such as N,N-ethyleneurea, NN'-ethyleneurea, NN'@dimethylurea, N,N'-diethylured, N,N'-dimethoxymethylurea, NNdiniethoxymethylurea, N,N'-diethoxyethylurea, tetramet t a, traet a. Similar react:@on products of forma dehyde with triazines, such as melamine may also be employed, such as NN-dimethyln-ielamine and alcohol-niodified m--Ian-dueformaldehyde thern-io-setting resin condensates, e.g. of methyl. and ethyl alcohols, for example, dh-nethoxymethyl-monomethylolmelarnine. The use of an auxiliary aminoplast with the diryandiamide polymers of the present invention se.-ves to modify the hand, and frequently increases the strength and res@istance to creasing, wrinkling, and crushin@ The auxiliary aminoplast binder may be used in an amount up to 25% by weight of the weight of polymer containing @dicyandiamide groups, 2 to I 1 % bein- preferably employed when the combination binder system is used. Whether or not an aminoplast bitider is used in conjunction ivith the polymer co@ntainin-g dicyandiamide groups, there may be introdu;c-,d diito the system either into the aqiicous dispersion of 'Lhe polymer or by separate aplvlicat@ion to the iionwoven flbrotis mat or web, before or after application of the aqueous dispersion of the polymer, a catalyst for sceelerating the curing of the binder through the dicyandiarnide groups, The catalyst maybe used in an amoun@t up to 2 %, preferably about 1/2 to 1% on the weight of the polymer. Thecatalyst used may be selected to iavoid exr-essive deterioration of the fibers used in the particular fibrous product, but it is in any case an acidic or potentially acidic material, the latter serving as a latent catalyst and liberatinacid on heating. For example, when @cellulos-ic fibers are enployed, a latent amnionium salt, such as ammonium chloride or idiammonium phosphate or ia latent aiiiinehydroehioride salt, may ibe employed such as thehydrochloride or triethanolam,uie, nionoethanolamine, diethylamine, and so on. The same catalyst may act as the catalyst for the aminoplast, if such is used.: It is believed that the binder of the present invention reacts with such fibers as contain reactive groups, such jas cellulosic flibers. If desired, the aqueous dispe,,rsion of the polymer containin.- @dicyandiamide units may also @contain a wetting a-gent to assist penetration of the fibrous web or ,Piat to which it is appl-iod, iand it may contain either a foaming agent to provide the binder in a foamed condition in the fthal product or it may contain a defoamer when the ingredients of tho,aq-Licous dispersion have a tendency to give rise to foamin.- and in a partictilar case such foamin@g is undesirable. l@e jeonventional wetting agents, such as the sodi@um salt of dio@ctylsulfosuceinate may be used and the @conventional :.Loaming and @defoamingagents may be em@ployed, such as sodium soaps, including sodium oleate for @foaniing and oetyl alcohol or certain silicones for idefoanlinig. Generally, the,proportion of the binder of the present invention to the weight of the fiber, component of the fibrous product may vary Nvidely depending on the cl-iaracter of the product!desired. The aqtieous dispersion of the polymer containing the dicyandiamide groups is generally applied at a concentration of 2 to 60% solids and preferably at a iconcentration of 20 to 40% binder solids by weight. The fibrous product of non-v/oven chara-,ter may contain from 20 to 200% by weight of binder on the weight of the fibers depending on the purpose for which the
[5]3)101@292 product is to be used. When the bindet is to serve maiiily to bond the fi@bers to.-ether to -form a coherent @uru'tary str,ucture in which the max-iinum porosity is retained in conjunction@ with a niinl:mum ichange of natural fiber hand, there niay be employed from 20 to 50% by weight of -5 binder solids on @fiiber, the lower piroportion, of course, giving the maxiinum porosity and provid-ing a minimum chan,ge in the natural fiber halad although even with the larger proportion in this range, the porosity is mainly retained and the fiber hand is still evident. The prod10 -ucts thus obtained are quite useful for many sanitary uses such as table napkins, bibs, table cloths, sanitary napkin covers, disposable diapers, disposable shects,.and Isurgicial dressings and icompresses. It.is characteristic of t-he blinder applied in the proportions just stated that there 15 is relatively little or no "window paning," that is, the interstices between fibers is left open leavin@g a hi-ghly porous bulk-y product. Of course, the density of the product can be effected or modified by the application, of pressure to varyin.- extents prior to or, in many cases, 20 even iafter the curina of the product' Fibrous produc4s of nlon-woven character using from 40 to 150% by weight of the binder of the present inv6ntion on the weight of the fiber are igenerally quite useful for garment uses to,provide interlining fabrics for 25 coats, dresses, and so; on,, or toi provide outer wearin-, appaxel fa@brics, such as blousm, skirts, shirts, etc. The -garments made of these fabrics need no iron-ing or pressing to restore their iappearance, shape, and hand after hand-washing, machine4aundering and drying operations. 3 0 Besides the general household and apparel uses mentioned,above, fiibrous products of the invention in which 20 to 100% -by vieight of binder on the wei-gh-t of fi@ber is employed, find many li.-ht industrial @uses as wiping cloths, lining rr@aterials for pa@,kaging asfilters, and pack35 ings,and gaskets for industrial machinery. Fibrous products of the present in-vention, in which 100% to 200% by weight of the binder on the weight of flber is used, a-re specially useful for heavy industrial uses where du,7ability and resistance to wear are desired, 40 such as in industrial gaskets, parkings, filters, and so on. Any of the produ@cts containing 20 to 200% of the binder of the present invention on the woight of the fiber are useful as laminating layers, either as interlayexs or backin@g sheets in con@junction with plastic films and sheet. as of polyethylene, nylon, and so on, or in conjunction 4 5 with textile fa@,brics of woven, braided, knitted, knotted, i)r felted character. It is essential that the drying of the treated fibrous product, that is the fibrous product carrying the binder .50 dispersion, be effected at a temperature above the Ti of the binder copolymer in order to effect proper coalescence and bonding of the fibers. As pointed out above, snce the Ti of the copolymer is about 30' C. or lower, no spegial heating is ordinarily necessary to effect bond- ti,5 in-., but it may be advantageous to aecelerate the drying of the binder to the set condition. To render the binder ..insolubl e, curihg at elevated temperatures is effected. Curing temperatures may be,as high as 400' C. for setting the binder, but preferably are in the range. from about 60 110' to 350,' C. The curing serves to reiider -the binder insoluble and infusible and, as stated hereinabove, may be assisted by the use of an acidic catalyst. As pointed out hereinbefore, the application of the polymer s containing dicyandiamide groups is adapted to 65 provide fibrous products having a wide ran-,e of character,isti es. When the binder is present in an amount df about 20 to 50% on the weight of the fibers in the fibrous product, the latter retains a textile hand and can have either a soft or a stiff texture depending on the propor- 70 tion of dicyandiamide groups in the polymer and the characteristics of any comongmers used in making it. Using polymers containing 3 to 20% of units containing dicyandi amide groups in conjunction with such comono10 of 20' C. or less and preferably not over 5' C., a soft resilient texture is obtained in conjunction with a textile feel,or hand and the cured product is quite resistant @to lauiidering, dry-cleaning, and spotting to various chemicals and heat. In -all of the fibrous products previously mentioned, where the binder may be present in the proportioly of 20 to, 50% as in the products just mentioned or in larger proportions up to 200% on the weight of the fiber, the products are characterized by freedom from discoloration and excellent resist@ance to ultraviolet light, to laundering (both home laundering and commercial laundering), to dry-cleaning and spotting, including drycleaning by means of solvent naphthas, carbon tetrachloride, perchloroethylene, and even by dimethylformamide, to various chemicals, and heat as in ironing, and durability of any embossed pattern. They are -also characterized by good adhesion of the binder to the fibers. The binder of the present invention is essentiall@ c6lorless and has -the advantage that it undergoes no discoloration at the elevated temperature needed for the drying or baking of such produrts. T@he fforous products of the present invention are ca-pable of numerous uses, many of which have been mentioned above. Thus, the fibrous mats bonded with the improved binders of the present invention may serve as heat or sound insulation materials, as filters for air systoms or liquid systems, as permeable membranes as in storage batteries or el6cirolytic condensers, as cushioning or I padding materials for upholstering purposes and so forth. The following examples are illustrative o'f the fibrous products and the methods for making them in accordance with the present invention and parts and percentages are by weight unless otherwise indicated: Example I (a) A 75/25 viscose (3 denier, I inch staple) /bleached cotton (iniddling, 15/1 inch) carded web weighin about 6 9 0.75 ounce/square yard is impregnated with an aqueous dispersion containing per 100 p-arts: 25.0 parts @of an emulsion eppolyrner of 60% ethyl, -acrylate, 25.5% @methyl - methacrylate, and 14.5% of methacrylyl dicya@ndiamide parts of t-octylphenoxypolyethoxyethanol containing 'about 35 oxyethylene @units (emulsifier and dispersiiia agent) 0.4 part of oetyl_phenoxyethoxysodiumsulfate (wetting agent) 0. 1 p,art silicone antifoam at a @wet pick-up of about 600% on the weight of -the fibers. The web is dried 1.5 minutes at 225' F., and cured 1.5 minutes at 350' F. The resulting non-woven fabric is iabout 40/60 fiber/binder weight ratio. It is highly porous and has a soft and resiliet feel. (b) The procedure @of part (a) is repeated with Pyrex filass fibers, elxcept that the carded web weighs 1/2 ounce per square yard and impregnation with the aqueous dispersion is effected at a wet pick-up of 300%, giving :a weight ratio of 56/44 fiber to binder in the final fabric which is extremely porous aiid soft yet coherent. Example 2 Tihe procedure of Ex-ample (I(a) is repeated using a similar -aqueous dispersion having the same contentration of copolymer but the leopolymer therein is a copolymer of 5% by weight of methacrylyl dicyandiamide, 809o by weight of ethyl acrylate, and 15% by weight of In-bLityl @crylate., A porous, soft, and coherent nonwoven webt is obtained quite similar to that of Example 1 (a). Example 3 The procedure of Example l(a) is repeated using a r.iers as result in providing a Ti value of tihe copolymer 75 similar aqueous dispersion having the" same concentration
[6]3,101,292 12 of copolymer but the copolynier therein is a copolymer ing of methaerylyl dicyandiarnide and acrylyl dicyandiof 50% by wei@ght of n-butyl acrylate grafted by subse- amide in which the acrylyl group has the formula quent copolymerization on to 50% by weight of a pre0 viously homopolymcrized metbacrylyl dicyandiamide. 11 Example 4 5 112C=CHCand th@- methacrylyl group has the f-ormula An all viscose (5 @denier, 1.25 inch staple) cardedweb 0 weighing about 2 oLinces/square yard is printed in a 11 design consisting of a plurality of spaced rings with an H2C=C (CH3) Caqueous dispersion containin.- per 100 parts: IO and at least 50% by weight of at least one monomer selected from the group consisting of styrene, chloro25.0 parts of acrylyl dicyand:iamide/butyl iacrylate/ethyl ,acrylate (10/20/70 by weight) emulsion copolymer 2 parts of t-octylphenoxypolyethoxyethanol containin,, alb,out 35 oxyethyletic iunits (emulsifier and dispersing 15 agent) Sufficient methyl cellulose to give a Brookfield viscosity of about 2,000 cps. at 75' F., with a No. 3 Spindle at 30 r.p.m. The web is dried one minute at 240' F., and cured t@vO 20 m-inates at 300' F. ne resultant non-woven fabric contains about 80/20 fiber/binder. The web is rendered coherent by the bonded -aiinuli and is porous throughout. Example 5 25 A 50150 white nylon/disperse-dyed bright acetate (both fibers 3 denier, 1.5 inch staple) random web obtained by air-deposition weighing ieebout 1.5 oz./sq. yd. is impre,-nated with an aqueous dispersion containing per 100 parts: 30 27.0 parts of methacrylyl dicy-andiamide/butyl acrylat@p-, 20/80 2 parts of t-octylphenoxypolyethoxyethanol containing ;about 35 oxyethylene units (emulsifier and dispersingy agent) 35 3.0 parts of (@dimethylol-NN'-ethyleneurea) 0.5 part of ammonium chloride 0.5 part of octylphenoxyetlioxysodiumsulfate (wetting agent)i 0.1 part of silicone antifoam 40 at about 3009o wet pick-up. The web, is dried 1.5 niinutes at 225' F., rured 6 tes at 350' F. Resultant non-woven fabric is ca. 55145 fiber/bin@der. It is quite porous and has an essentially textile hand. After wash45 ing @and ldrying, no ironing or pressing is needed to restore the shape, appearance, or hand of garments m@ade of the fabric. Example 6 'Ihe procedure of Example 4 is repeated with air50 deposited webs obtained from the following flbers: (a) 50% viscose rayon with 50% of a polymer of about 85% to 90% acrylonitrile iavailab@le- under the nanie "Acrilan," 55 (h) 55% nylon (polyamide 66 type) with 45% viscose @rayon, (c) 100% cotton (garnetted card waste, roving yarns), (,d) 100% nylon, iand 60 (e) 35% cotton with 65% @poly(ethylene glycol terephthalate) (Dacron). We
