US2610935A - Creped paper product and process - Google Patents

Description

Filed Feb. 24, 1949 Sept. 16, 1952 w. W. ROWE 2,610,935

CREPED PAPER PRODUCT AND PROCESS 2 SHEETS- SHEET 1 had www

HTTORN EYS.

Sept. 16, 1952 W W ROWE 2,610,935

CREPED PAPER PRODUCT AND PROCESS Filed Feb. 24, 1949 2 SHEETS- SHEET 2 s: E /ZZ F IG. 6'. E f4 1E -21 INVENTOR. WML/4M [Mu/.ace /fows Hwa/7M ATTO RNEYS.

Patented Sept. 16, 1952 rear ofFFieE 2,610,935 CREPEDPAPER'PRODUCT ANDPR'OCESS;

William Wallace. Rowe, Cincinnati, Ohio,.assignor toCincinnati Industries, Inc., Lockland, Ohio,l a' corporation of. Ohio Application February 24, 1949,' SeriaLNo. '78;197

Theprincipal: objects-.oi my invention are-the provision ofimproved. creped paper materials and .methods ofY makingfthem.

In this connection: objectY ofw the.: invention isv the'provision of a mode of t operation. whereby the absorptivity of papermaterials may be greatly and usefully increased. Thisincrea'se appears to bedue to an openingup of thefinterior structure of the. paperr Webs'. referred. to hereinafter for convenienceas interfacial disruption."

mother object of thefinventionis the provision ofcreped paper. products having the-novel characteristic` of exhibiting; crepi-ngfcrinkles on one side only, suchproductsgbeing hereinafter referred to for convenience as.twosidedacreped products-i.

Thesel and other objectsfoi: my invention, which will beset forth hereinafter or will be apparent to one skilled-in the art upon reading these specifications; I. accomplish in those products and procedures: ofwhich I. shall now set forth .exemplary embodiments.4 Reference is madeto the'accom'- panyingdrawings .inwhichz E'igure 1. isza photographic' reproduction. of a creped paper product in accordance with my invention.. showing. the side thereof Whichwaslocated av/'ayl from. the creping cylinder.Y

Figure 2 is a similarfreproduction ofvacrepe paperA product. showing the-A side: thereof' which lay aganstthe creping-'cylindersduring :the .creping operation.v

Figure 3: is a diagrammatic representation on an exaggerated vscale of one type of creping action which .normally Yoccursiwhen Websiare creped by meansy of a positive: adhesives.

Figure 4 is`a similar diagrammatic representation of another type of creping action which normally'occurs-when Webs are crepedbymeans ofl sentation of a creping cylinderwithmeansfor coating/and combiningA Webs.

Myl invention relatesto creping-processes; in Which aiweb of paper is caused to adhere to the creping surface by means of :a positive adhesive substance.

Preferably, the substance is thermo-1.

plasticincharacter and hence ,subject to. control atl-the creping: point. through temperature. Creping by means of positiveV adhesives istaught in my reissue patent .,No. lie.,17,33.y The teachings of thepresent invention. are. particularly.` valuable in the. manufacture. of paper. webs. which are stretchableinall directions Such.vvebsniayy be those made. by the general.. process. and'. onV the apparatus of thev Kemp. Patents 2,071,347, 2,008,182 and 2,008,181, or maybe. those made by theprocedure and-apparatus of the.V copending application of i Raul W. Dorst,. Serial No. .686,899., led July 29, 1.946,y now` Patent No. 2,494,334, issued January 10, 1950. For the., purpose. of setting forth an exemplary embodiment, Ishall describe my invention. in connectionv with the procedure and apparatus. of theKemp patents.

In this procedure` andapparatus, the. paper web is caused to adheretothe surface. ofarst creping cylinder fromwhich itis removed. and contracted by the action of a-knifeor doctor disposed substantially helically on the surface of said cylinder and at a. substantial angle toA the longitudinal axis of the. uncreped Web. As it leaves the knife, thepaper is reversed. i. e. turned upside down, and is carried away from Vthe creping cylinder generally in .the direction :ofthe axis of that cylinder, to a second creping cylinder oriented usually at-rightangles to therst. It is causedto adhere'to the Ysecond* creping cylinder, usually by the` same coatingof.v adhesive, and is removed from itssurface andfurther gathered by another' substantially helical knife, disposed in such away as to-producecreping crinkles oppositely disposed lto the. rst-creping crinkles. Both sets of creping. cringles are -disposed` aslant to the long-itudinaliaxis of the gathered-Web, and since the sets of crepingcrinkles crosseach other, the web .is so. gatheredasto-be universally stretchable. i

The use oa positive .crepingiadhesive generally results inthe. formation of veryT fine creping crinkles even.in..heavy=v Webs` by reason ofthe comparatively great'force required to .remove the paperfrom the creping. cylinder and-the uniformity. of its adhesion thereto,Y as compared with Water crepedproducts which arecharacterized by relatively very, coarse crinkles.1 and frequent skips Wherethe paper. appears tohave broken away from the cylinder for-substantial-distances in `advancing of the knife.

In crepingwth positiveA adhesive substances existing ascoatings. of substantial. thickness on the surface ofa web, it/.has-been noted that'the coating substance must vbe sufcientlyviscous and 3 have sufiicient body to transmit the creping force to the web. Otherwise the web may simply slide off over the knife without creping. With thinner coatings of adhesive, the requirements for viscosity and body become less. In creping, the knife crowds the web back upon itself and forms creping crinkles which are in the nature of minute folds in the paper web as such.

This action, and hitherto the only action obtained by the art in the creping operations employing positive adhesive substances, is believed to be that illustrated diagrammatically in Figures 3 and 4, where I represents a creping surface, such as the surface of a crepingT cylinder, to which a web of paper 2 is caused to adhere by means of a layer 3 of positive adhesive substance. The thickness of this layer has been exaggerated for clarity. The paper web is removed from the creping surface I by adoctor or knife d, the leading edge of which forms with the surface of the cylinder a creping V of desired angular-ity.

The knife 4, being stationary in space while the cylinder I in Figure 3 turns in a counterclockwise direction, serves as an abutment in the path of both the layer of adhesive and the paper web, exerting force on them in a direction opposite the travel of the web as produced by the cylinder. In a water-creping operation, where the web clings to the surface of the cylinder because of atmospheric pressure and due tothe water seal, it is believed that the web breaks away from the surface of the cylinder in areas ahead of the knife, thus starting folds which are completed by the movement of the paper against the knife. Where the paper is bound to the surface of the cylinder by a thermoplastic, positive adhesive, a somewhat similar action may occur, depending upon the condition and thickness of the adhesive which may come away from the surface of the cylinder as at 5 in Figure 4, or from the paper, or may part Within itself in any case starting a fold 6 in the paper ahead of the knife, which fold collapses against the knife to form a crinkle. If the adhesive is plastic in nature while adherent to the paper and cylinder, the knife 4, as illustrated in Figure 3, produces a displacement of the adhesive in the nature of a thickening thereof as indicated at 5a. This in turn permits the paper layer to move upwardly as at 6a slightly ahead of the knife, thus starting a fold which is completed as the-paper-moves against the knife. The adhesive, somewhat thickened in the valleys of the crinkles as viewed from the adhesive coated side of the web, leaves the surface of the cylinder with the web excepting for a thin resident y film. The paper web 2, however, is bodily folded into creping crinkles diagrammatically indicated atl 'I. In all of these instances, crinkles of substantially the same depth and appearance are visible on both sides of the web if the adhesive is removed, as by extraction with a solvent.

The teachings of this application are essentially directed to a different type'of action obtained as hereinafter more fully taught in detail. I

have discovered that it is possible to contract a ,4 distorted as at 5a in Figure 3 so as to acquire surface rugosities sufficiently large to be followed by the paper web, i. e. to permit the paper web bodily to buckle just ahead of the knife to form an incipient fold. On the other hand, the adhesive has sufficient strength and cohesion that it will neither separate from the paper or the cylinder, nor split within itself as in Figure 4. The adhesive 9 binds the paper web 8 to the surface of the cylinder I so strongly that the strength of the bond is inherently greater than the resistance ofthe paper to internal disruption.

Under these circumstances, as the paper web 8 is moved against the knife 4, several actions appear to occur. First, the adhesive layer 9 (excepting for a thin film normally resident on the cylinder) is substantially smoothly, uniformly and continuously removed from the cylinder by the knife, and greatly retards, and may entirely prevent the formation of crinkles on the under side of the paper. Second, the upper surface of the paper tends to form into creping crinkles. These actions are mutually inconsistent, as will be evident. Hence a third action occurs to make the other two possible. This is an actual disruption of the interior structure of the paper. The surface of the web which lies away from the cylinder is displaced upwardly as at I0 in the formation of an incipient fold or creping crinkle. But since the lower surface of the web is bound to the surface of the cylinder I so strongly that it cannot move away from the creping surface until actually scraped therefrom by the knife fl, the formation of the displacement of the upper surface of the paper, indicated at I0, implies and produces an actual thickening of the paper web, and hence an internal or interfacial disruption thereof. Both sides of the web are of course contracted. The contraction of the upper portion resides in creping crinkles of normal form and appearance. The under surface of the paper web is scraped from the surface of the cylinder I with a crowding together of its fibers, but with a complete or substantial absence of creping crinkles. The result is a web creped or crinkled as to its upper surface layers, but smooth, substantially smooth, or exhibiting creping crinkles to a very much less extent on its under surface, accompanied by an interfacial disruption or rearrange- `ment of the fibers making up the web in order to permit this differential activity to go on. The internal 0r interfacial disruption of the paper web can easily be seen in section under the microscope at 50x or greater, for ordinary kraft wrapping papers, and is further evidenced by the marked increase in absorptivity of the product, as hereinafter set forth.

By carrying on the type of creping operation illustrated in Figure 5 with very thick and heavy papers, the internal disruption of the web becomes clearly apparent to the naked eye at cut edges thereof. The upper surface of the web is formed into relatively heavy and coarse creping crinkles, while the under side of the web is smooth or substantially so. The interfacial disruption in such thick and heavy webs is sometimes s'o great that the treated web may readily be separated into two layers, one a thin'layer of smooth character which was the side of the web lying next the creping cylinder, and the other a heavier layer having the creping crinkles on its upper surface and presenting the appearance at its lower or disrupted surface of a very substantial opening up of the brous structure. With thinner webs, such as those ordinarily emplayedv in the :manufacture or creped-1 products, the same sort of condition prevails, although with such thinner webs" the A interfacial disruption is not'lapparentto the eye, and such productspresent-the novel appearance of 'beingv creped normally 'upon oneside and uncrepedupon the other.

The new productshave la number-*of"novel and valuable characteristics. For example it has hitherto been known that ordinary creping will increase the absorptivity-of a paper to a slight degree, since the bare act of folding the paper into creping crinkles opens it up slightly anddisturbs to some extent the relationship of anysizing in thepaperto the fibers which make up the Web. My new products, however, exhibit an astonishing increase in absorptivity, which` is4` due to the interfacial disruption I have described;

By Way of example, a hard sized, sixty-pound kraft paper, creped by vmeans of asphalt as'the positive creping adhesive Aafter the manner illustrated diagrammatically in Figure 3, andy beinga one-sided product in that'theV creping'crinkles are substantially thesame on both sides of the web, has by `reason ofV its lack of interfacial disruption, a relatively low absorptivity. When suchoa paper, after extraction of the asphalt, is treated with..a dispersion of a synthetic rubber such as neoprene containing'36% solids; it will absorb only about 20% of the rubber solids, based on` the Weight of the web. The same paper crepedasl diagrammatically illustrated in Figure 5, so asV to be tivo-sided in that it has crepingcrinklesupon one face and an absence or substantially'absence of them on the other, when treated with the same rubbery dispersion Will absorb about 35% of the rubber solids based on itsV Weight. This surprising increase in absorptivity holds good for all other substances capable of being absorbed into afibrous web, such as solutions of saturants, normally liquid saturatingV media, and thermoplastic substances which can be brought to saturating ccnsistencies underv heat. Valuable products may be made froml my treated papers which were hitherto not L possible in the art. The resilience and tear strengthsV of papers may thus be very `greatly increased'by saturating them withlatex and dispersions of rubbers, both natural and: artificial,

and rubbery' and resinous substances derived from them by saturation. It will be evident also thaty since the process of this invention very greatly increases the absorptivity of hard sized, dense and strong papers, these papers which are ordinarily much less expensive, may be substituted for the more expensive, special, openj unsized webs hitherto employed in resin molding. operations, and in rubber. saturating operations.

Yet again, the practice of my invention kenables me to produce creped paper products which are By contracthighly contracted and have high degrees of 75.

stretchability, especially universal-lyy stretchable webs as hereinafter set forth, which are -crinkled on :one side only 'and hence-are especially valuable inv the production oil-embossed products like artificial leathers, in uses where coating substances must bei uniformly and'economically applied to one'side-of the creped paper webs, and in uses where contracted paper Webs must be uniformly cemented against other surfaces, with a minimum of* adhesivev coating.

InFigure 1, I have shown aiphotcgraphic representation at I2 of *a universally stretchable creped paper product made in accordance with my invention', the view being of that side of the product Which lay away from the creping drums during the ycreping operation.

Figure 2 shows atl3-the .opposite facefof the same product; It will thus be seen that this product-` isV characterized by Acreping crinliles on one surface, and' on the :other by a complete visual vabsence of 'crepingcrinkles Ijshall now describe a pre-ferredmodeof manufacture of vmy 4r'ovelcreped paper products.

Referring to Figure 6; I have shown diagrammati'cally a doublecreping machine of the-Kemp type'. A webl ofY paper' I4, which is coated on its underm surface with adhesive, is pressed by meansoff-'a pressureroll l5 against the surface ofa rstfcreping'drurn- I5, provided with a diagonalknife Il. Through'the operation of this apparatus, the-paper# isecontracted both widthwise and lengthwiseby the formationtherein of diagonal creping crinkles or gatherings. The paper-so treated, as 4at ma is conducted to a secondicrepingcylinder"l'and pressed against its surface byapressureroll I9. A diagonal knife or doctor'Z'renlovesY the paperffrom this cylinder, imparting to itdiagonal creping crinkles extending oppositely to those imparted by the rstiknife: The doubly contracted and universally 4stretclrable webs indicated in Figure 6 at Mb:

In accordance with this invention the creping adhesive employed may be Aapplied to the web ld or toA thecreping'surface in any suitable way as by spraying,doctoring orthe like. I prefer to employan applicatorroll 2| turning in the pan 22 of the adhesive substance; Ima-y employ a doctor or Vmetering device to gauge the nlm o-f'dispersions picked up bythe roll 2l. A smoothing element 25, such asa small diameter roll turning oppositely to the travel of the paper Web may be employed if desired;

In theV light of the discussion above of the action illustratedl in-Figure 5, it Will be evident that various'factors'have a bearing upon the obtaining of the effects inherent in my novel products. The resistance of the Web to interfacial disruption is one ofthese, inasmuch as it is easier'tc obtain a two-sided productH with a web which is more readily disruptable, and in general with thicker webs as compared Withthinner Webs. As to the ease with which the brous structureof a web may bev disturbed, various factors are also involved. The .nature of the fibers in the sheet is one. Thedegree of` openness ofthe sheet, its density, whether orv not it hasbeen .calendered, areothers. The amount off internalsiaing may be important, andborderline conditions can be found which will produce a two-sided effect with aslack sizedpaper butwill produce a one-sided crepingeffect'withahard sized paper, otherwise the same. However the teachings of this invention are applicable to paper webs in general, rand 7 two-sided creping may be practicedwith most types of paper webs.

Irrespective, however, of the initial character of the paper chosen, the operator has substantial control over its resistance to disruption, since it is readily possible for him to soften the paper temporarily as by wetting. The amount of water introduced into the paper and resident in it at the creping point oridinarily controls, though in some instances the softening effect will be progressive, so that wetting the paper for a greater or less time prior to creping will affect the strength of the paper. The use of wetting agents in the water will frequently assist in the softening of papers.

As has been indicated, the nature and disposition of the creping adhesive is of importance. The adhesive must be employed in a layer such that the creping knife or doctor cannot displace it as illustrated in Figure 3 to the extent of permitting the paper web to form, bodily, an incipient fold or creping crinkle ahead of the knife.

Putting this anotherv Way, the adhesivev must not tend to be displaced ahead of the knife in such fashion that its upper surface will form into corrugations or ridges large enough to be followed bodily by the paper. With usual adhesives this implies either a thin layer, or a discontinuous layer, or both. The conditions of creping can be widely varied. as will p-resently be seen, and extreme thinness and discontinuity are not necessary limitations. Nevertheless, it will not be found possible to accomplish one-sided creping with so heavy a layer of plastic adhesive that the action of the creping knife on the adhesive alone would be to form crinkles or corrugations in its upper surface suitable for imparting similar configurations to the paper web.

Again, the adhesive must not be such as will permit the under surface of the web to become free of the surface of the cylinder suciently ahead of the knife to permit the knife to form crinkles or folds in the under side of the web as the web is contracted. Thus an adhesive in a hard or brittle condition such that it tends to split away from the cylinder or split within its body well in advance of the knife is not suitable. It goes without saying that an adhesive which has so little cohesion and adhesion that the creping doctor or knife can scrape the paper from the surface of the cylinder without contracting it at all', cannot be used.

The adhesive in the thickness and condition employed must be so strong and cohesive under the circumstances of creping as to bind the paper to the creping surface with a force greater than the resistance of the paper web to internal disruption. The web must be equally contracted as to both of its faces, and while the upper surface of the paper will form into creping crinkles accompanied by internal disruption of the web, the inner or lower surface of the paper must remain firmly bound to the surface of the cylinder without moving away from that surface, to the very point where it is contacted and gathered by the creping knife by crowding itsI fibers together, and without the production cf the rugosities ordinarily recognized as creping crinkles.

Thus the nature and disposition of the adhesive should be such that the paper is prevented from bodily separating from the cylinder either through release of the adhesive bond or through displacement of the adhesive ahead of the knife, and beyond this the requirement for the adhesive is that its bond and cohesiveness should be greater than the resistance of the particular paper web to internal disruption.

The cohesion and consistency of most adhesives can be controlled in various ways as by solvents or by the use of heat or temperature control if the adhesives are thermoplastic. I have indicated above that the resistance of the paper web to internal disruption can also be widely controlled. Thus the invention may be practiced with a great variety of adhesives.

The choice of adhesives is wide, for most strong adhesives in thin layers will have or can be made to have a sufficient internal strength and such adhesives include in general bitumens, resins, natural and articial, glues and rubbery substances, and mixtures of them. Since the adhesives are employed in thin layers, it is desirable that the same adhesive be used for affixing the web to the second creping cylinder as was used in affixing it to the first, and without the addition of a further adhesive increment. Thus the adhesive is preferably one which can be reactivated at the second creping cylinder, and since this is most readily done by controlling the temperature of the second cylinder, my preference is for a thermoplastic adhesive. Rubber as such is not classed by me as a thermoplastic or thermosensitive adhesive. t is principally, if not entirely, pressure sensitive only to itself for creping purposes when dry, and this is true whether the rubber be derived from latex or other dispersion, or from a solution. Consequently, while pure rubber may be employed to adhere a web to a first creping cylinder, it will not adequately cause it to adhere to a second creping cylinder unless additional dissolved or dispersed rubber be employed.

Many adhesives in which rubber is combined with resinous or bituminous substances are. however, suitable for my purpose.

In general, the coatings of adhesive employed by me are thin, and this may present a problem of application. Because a small qua-nity of the adhesive is employed, it must be kept as a superficial coating on the web, since to the extent that it is drawn into the web by capillarity it will be ineffective in affixing the web to the creping cylinder and will strengthen the web against interfacial disruption. It is quite possible to bring a thermoplastic adhesive by heat or by dispersion to a consistency at which it may be sprayed in a thin enough layer on the surface of a web of paper, and discontinuities in a coating thus produced are not disadvantageous providing they are fine and uniform. However, spraying equipment is costly and liable to sporadic variations in use. If the viscosity for application is attained through the use of organic solvents, there is an added factor of expense, and of equipment if solvent recovery is attempted. An attempt to cut back an adhesive with solvent to a low enough viscosity to permit roller coating in a thin layer as required by my invention may result in the solution attaining a saturating viscosity which will leave the adhesive within the web rather than on its surface.

In the practice of my invention, the easiest way to obtain a coating of suitable adhesive of sufficient thinness and evenness of distribution is to employ water dispersions or artificial latices of the desired adhesives. There are a large number of such dispersions which may be employed. In general, they comprise dispersions of any of the natural or synthetic resins which either are continuously thermoplastic, or if quantity of solids i-n thedispersion-as compared withA the quantity-of the water vehicle.- canfbe. very carefully controlled, i as` by, *simpler dil-uti'or-i,v so that the film of: solids applied to--the webrcan be controlledv with great uniformity-andi accuracy.A

The dispersione are: of -relatively lowfyi'scosity-dn relation to the quantity of solids they c ontain-,- so that they are` very easily.r handled in.- coating apparatus such as hasrbeen.describedabove..

Although the'v disp'ersionsfare .non-tacky the dispersed form, when they are applied tor the webs of paper, the aqueous-1vehicle.is-rapidlyfabf-y sorbed by the webs, breaking the emulsion. and: depositing the adhesivel solids oni thesurface of. the web. The. nature of,- thefdispersions is: such:

that the particles; of adhesive they containtend:-Y

to: filterV out upon the surface of a web! asr the aqueous Vehicle is absorbed therein, so as tofforrn. an almost entirely superficial filmforl coating Aof thev solids on the web;- @neef the emulsion isbroken, itd'oes-not tendftoreform;v and thefpresencey of water in the-web does not-.prevent the activation of the4 adhesive-solidsr-bytemperature The aqueous vehicleV of thedispersions' is useful in wetting and hence softening thefwea control.

andl in interfacially weakening, thefweb. particularly on that; side to. whichfthe adhesive-is; aph plied. If the quantity of water in'vl the aqueousvehicle is not sufficient to strike through:thefweb-I and meisten all parts ofnit, additinnalawetting can be accomplished easily from? the omeosite.l sideof. the web to bring about; asthoro'ugh: soft'-` ening.

Theuse of dispersions enables? niet: to:` form-s exceedingly thin ooatingsfsofc adhesivevsubstances of great strength, which:- coatings' men wholly: superficial. It' can'Y be; demonstratedwitlzn dispersions that when all.YV other" conditiunsiremain. the same: the dierenc. betweenfone-sided?andy two-sidedcreping cairbef'merely aA matter of;

quantity of solidsk appliedrper unitlofarea'offtheweb. .Thus iffoneL-sidedcrepingf'is; accomplished with a Vdispersion containing a high quantity of solids. and hence. forming ai comparatively layer of adhesive/on. ther' surfaceozff the: web; two-sided creping ina-.y bei obtainedifunder' identical conditions by simplysuffici'ently'diluting the same dispersion! asf"appli'e thinness of the coatingrwhich will producetwivof` sidedf ereping or a-substantiali'nterfacialdisru tion ofthe web will Vary to asubstantialexte tlY with the,v thickness of tlief web;i thedegree@ fof softening thereof; as bywat'er, and'f-the natural resistance of the web: to internal-disruptioni Because of the interplayw of the factors described above, it is notpossibl'e' to' givespecific directions for, all papers'and for' alljadlresi'ves; By way of asingle', non-limitative'exarnple; I' consistently obtain two-sidedcreping with` ore dinary 30-pound kraft wrappingpaper;4 using a' dispersion of polymeriz'ed" wood r'osi'n, and 'applying it in such fashion as to producea coating' of about one` and one-half'"pounds` ofsolidsper 'Bhe-r specifici aicioiee l() thousand square. feet of the web surface. Since the desired thickness of coating will varywith the nature of. the adhesive, the nature ofA the web being treated, andthe degree of softening to which it has. been subjected, specific ranges of thickness of the ladhesive are not controlling. I have secured one-sidedv cfepi'ngvv with layers of adhesive ranging. from approximately onetenth to three or more-pounds per* thousand square feetv of the web surface, the Vgeneral operatingf rangef preferred byv me lying between approximately. one-halfY and two vpounds per thousand square feet for most webs and most adhesives;-n Givenf an. adi-lesivewhichcan'. act

to prevent! the weblr'ffrrn. separating from'v theY cylinder ahead` o-f the'.crepingkflfnife,v so as to humpv u'p. bodily into incipient creping crinkles,

the. question then. becomes one. ofiA attaining.A a.

bond. which.` is stronger thanfthe resistance of the. paper web. to.. internal! disruiiition'. This may be accomplished either by increasing theinternalA cohesion. ofV al particular adhesive as by temperature-control andthelile discussedab'ove; by selecting anV adhesive having. greater internal cohesion, by weakening. the web to a greater extent as, discussed above, or. by selectingV awebr hai/ ing` less Vresistance to. internal'v disruption.

Referring to: Figure 7,1. I have shown a web 23 being WitIdraWnfromr a supply roll 25B" and,I by means of suitable idler rollscarried across a coating rolll 2]. turning in the. pan 22 of dispersion. and: being. treated'fl by the smoothing bar or roll 2.5; As already indicated, as soon as thev aqueous vehicle ofJtheud'i'spersion strikes intothewebftheemulsion breaks and the solids` are. depositedupon the web. surface, theaqueous vehicle. serving tol softenthe web'. The web' is then-pressed againsttliefsiirface of tlie creping. drum lff'by the'pressure'roll.v I'5. IfA additional wetting of. the web. is desireithis may be accomplished:v as: at.. ZG by flow-ing water. into the pinch. between the pressure rollf l5 and the creping roll- I-Ei'l` Y The. temperature offth'ecrepihg' roll Itr will be controlled. to activate the ad'- hesive solids` and produce a strong adhesionbf adhesive; and pressed-Y by. the.v pressure roll-rl t5! against-the surfacefo'f. thef creping cylinder lfl A` secondweb 30withdraWn-from a supply roll 3l. is coated' as. at 3-2- withvanaqueous dispersion.-

and,1 carried'y beneath'- the crepng. cylinder It on: a-vy4 pluralityy of' idler rolls, is"v combined with thezweb 2:1 against thesurfaceo the cylinder I6 by the'f-pressurefrcll l-5. Itwili be notedthat here'. both. rwebs are?. softenedifby lthe aqueous ve- Y hi'cleoffth'e dispersions'employed;f the` websrwillfbef solidly" combined andr cenien'ted' together the: adhesive' applied to the'sec'orrd'iiweb..

'By methods. hereinabove set* frortl1,. have` succeeded-in producingfsinglef. andrdouble reps-di' papers bearing upon that surfaceyflfrioirV layy against? the creping cylinder" or cylinders j coating oiia'di'iesive substance'- ternperat-ures', which-lis "preferably "1i substance, while the fineness and evenness of the creping crinkles or gatherings is such as can only be produced with a positive creping adhesive, and with such an adhesive, only in the event the web or webs were thoroughly softened by wetting at the time of creping.

My novel products have a wide range of utility. In general they are of high value whenever a universally stretchable web is desired without the appearance at one external surface of the roughness characteristic of creping crinkles. Hitherto, in the making of artificial leathers by way of example, from coated, doublediagonally crepe papers it has been desirable to emboss the product so perfectly that any appearance of creping crinkles (as distinguished from the embossed design) is destroyed by pressure. This meant the taking of tedious and expensive precautions in the manufacture of the embossing dies, which, with allowance for the thickness of the paper web had to be made to mate exactly so as to subject all parts of the web to the same heavy pressure. With my new products this precaution is no longer necessary. The products, when coated on the smooth side, have no visual appearance of creping crinkles to begin with nor do creping crinkles become apparent when the product is stretched. Hence the provision of an embossed product in which the embossed design appears free from the extraneous design of creping crinkles is not dependent upon the exertion of high and uniform pressure on all parts of the web. The embossing dies do not have to be made so as to be capable of exerting such pressure. A light impression or a heavy impression may be made, depending upon the effect desired; and in no instance will there be apparent upon the surface anything but the embossed design. Herein and in the claims which follow the terms emulsion and dispersion are used interchangeably and without distinction to indicate a suspension of one normally incompatible substance in another.

Modifications may be made in my product and procedure without departing from the spirit of the invention. Having described my invention in certain exemplary embodiments what I claim as new and desire to secure by Letters Patent is:

1. A process of creping paper which comprises treating a paper web with a water dispersion of thermoplastic adhesive, causing the adhesive to come out of the dispersed phase and activating the said adhesive for creping purposes by applying heat and pressure thereto to develop sufficient tackiness to bind the web to a creping surface, the said dispersion being applied tc the paper web while the web is in a substantially dry and absorptive condition, in which process the breaking of the dispersion is produced by the absorption of the water vehicle thereof by the paper web and in which the said water vehicle serves to soften the paper web, at least at that surface against which the said adhesive is applied.

2. The process claimed in claim 1 wherein the paper web is additionally softened prior to creping by the application thereto of water on the opposite side.

3. In a process of creping paper in accordance y with the process of claim 1 the steps of treating a pair of paper webs with dispersions of thermoplastic adhesive applied to one side of each web under conditions in which such Webs can absorb the water vehicles of such dispersions and become softened thereby, leading such webs together so that one such coating of thermoplastic adhesive will serve to laminate them, leading the webs together against a creping surface with the other of said adhesive applications between said surfaces and the Webs, and creping the Webs together while said webs are so softened.

4. The process of claim 1 wherein the adhesive is applied in a layer containing no more than about 2 pounds solids per 1,000 square feet.

5. The process of claim 1 wherein the adhesive is applied in a layer containing no more than about 2 pounds solids per 1,000 square feet, and wherein the creping operation results in interfacial disruption of the web by forming unequal gatherings in opposite sides thereof.

6. The process claimed Yin claim 3 including the step of applying additional water to said Webs on the sides opposite the application of said dispersions.

7. A process for the purpose described comprising applying a water emulsion of a thermoplastic adhesive to a web under conditions in which said web absorbs the water vehicle of said emulsion and breaks said emulsion, using the coating of thermoplastic solid on the surface of said web to bind it to a creping surface and creping said web while it is still wet with said vehicle, afterward reactivating said thermoplastic solid by heat and causing it to adhere said web to another surface.

8. A universally stretchable, double-diagonally creped paper product comprising a single thickness sheet having on one side rugosities characteristic of creping crinkles, the opposite side being devoid of such rugosities to the extent of having the general appearance of plain, uncreped paper.

9. A universally stretchable creped paper product comprising a single thickness sheet having one side smooth and free of the appearance of creping crinkles.

10. A universally stretchable creped paper product comprising a single thickness sheet having one side smooth and free of the appearance of creping crinkles, said smooth side having the property of being stretchable to the extent of the resilient stretchability in the product, without loss of its said smoothness.

11. A universally stretchable creped paper product comprising a single thickness sheet having one side smooth and free of the appearance of creping crinkles, said smooth side having the property of being stretchable to the extent of the resident stretchability of the product, without loss of its said smoothness, and bearing a surface coating of creping adhesive, which coating contains no more than substantially one to two pounds solids per thousand square feet.

12. A process of creping webs with the interposition of adhesive material between the web to be creped and the creping surface, which comprises binding paper to a creping surface by means of a positive adhesive substance and removing it therefrom with a creping knife, employing for the purpose a layer of adhesive such as will not permit separation of the web bodily from the cylinder ahead of the creping knife so as to form incipient crinkles therein, and proportioning the cohesive strength of the adhesive to the resistance of the paper to internal disruption, so as to provide a bond which is greater than the said resistance.

13. A single thickness web of paper contracted in area by creping, vcharacterized by creping rugosities on one surface which are not matched by conjoint rugosities on the opposing surface 13 and further characterized by voids in the internal structure of the web.

14. A single thickness creped paper web characterized by localized inequalities in the cross sectional thickness of the creped web, said in- I come out of the dispersed phase and activating v.

the adhesive for creping purposes by applying heat and pressure thereto to bind the web to the creping surface, and proportioning the cohesive strength of the adhesive to the resistance of the paper web to interfacial disruption so as to provide a bond between the web and the creping cylinder which is greater than the resistance of the web to interfacial disruption, the cohesive strength of the adhesive also being such as will not permit separation of the web bodily from the cylinder ahead of the creping knife so as to form incipient crinkles in the adhesively coated surface of the web.

16. A stretchable creped paper product comprising a single thickness paper sheet opposite sides of which are equally contracted areawise, one of said sides being characterized by readily visible and substantially uniform creping rugosities throughout, and the other of said sides being relatively smooth and relatively free of the same rugosities, the different physical characteristics of the contraction of the opposite sides of said sheet of paper resulting in a disruption of the internal structure thereof and the opening up of the sheet whereby it is made more absorptive.

17. A process of producing a single thickness, universally stretchable creped paper product having a crinkled side and a substantially smooth side, which comprises binding a paper Web to a creping cylinder by means of a thin layer of positive adhesive and removing it therefrom with a creping knife, while proportioning the cohesive strength of the thin layer of adhesive to the resistance of the paper Web to interfacial disruption so as to provide a bond between the web and the creping cylinder which is greater than the resistance of the web to interfacial disruption, the cohesive strength of the adhesive being such as will inhibit separation of the web bodily from the cylinder ahead of the creping knife whereby to inhibit the formation of visible creping crinkles in the adhesive surface of the web.

18. The process of claim 1'7 in which the creping adhesive is a substance derived from a water dispersion of rubbery and resinous materials and in which the water Vehicle is absorbed by the paper web to soften it during creping.

WILLIAM WALLACE ROWE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 818,500 Wilkinson Apr. 24, 1906 1,823,877 Cannard Sept. 22, 1931 1,914,869 Rowe June 20, 1933 1,928,045 Angier Sept. 26, 1933 2,161,092 Rowe June 6, 1939 2,399,256 Rowe Apr. 20, 1946

Claims (1)

1. A PROCESS OF CREPING PAPER WHICH COMPRISES TREATING A PAPER WEB WITH A WATER DISPERSION OF THERMOPLASTIC ADHESIVE, CAUSING THE ADHESIVE TO COME OUT OF THE DISPERSED PHASE AND ACTIVATING THE SAID ADHESIVE FOR CREPING PURPOSES BY APPLYING HEAT AND PRESSURE THERETO TO DEVELOP SUFFICIENT TACKINESS TO BIND THE WEB TO A CREPING SURFACE, THE SAID DISPERSION BEING APPLIED TO THE PAPER WEB WHILE THE WEB IS IN A SUBSTANTIALLY DRY AND ABSORPTIVE CONDITION, IN WHICH PROCESS THE BREAKING OF THE DISPERSION IS PRODUCED BY THE ABSORPTION OF THE WATER VEHICLE THEREOF BY THE PAPER WEB AND IN WHICH THE SAID WATER VEHICLE SERVES TO SOFTEN THE PAPER WEB, AT LEAST AT THAT SURFACE AGAINST WHICH SAID ADHESIVE IS APPLIED

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