US1722434A - Process of making felted fibrous compositions - Google Patents

Description

July 30, 1929.

L. KlRscl-IBRAUN: 1,722,434 PROCESS MAKING FELTED FIBROUS CQMPOSI-TIONS I original Filed Nov., 19. 1924 :s 'sheets-sheet 1 July 3 0, 1,929. I KmscxHlaRwN 1,722,434

PROCESS 0F MAKING FELTED FIBROUS COMPOSITIONS Original Filed Nov. 19. '1924` 5 Sheets-Sheet 2 July 30, 1929. KlRscHBRAUN 1,722,434 PROCESS 0F MAKING FELTED FIBROUS COMPOSI'IONS Original Filed Nov. 19I 1924 '3 Sheets-Sheet 3 Patented "July 3o, 1929.

PATENT oFFIcE.

UNITED STATES LESTER KIRSCHBBAUN, F LEONIA, JERSEY.

' PEocEssor MAKING FELTED Emmons comrosrrrons;

Original application led j lovember 19,19%', Serial No. 750,927. Divided and lthis application led .AprilV 15, 1927. Serial 110,184,074.

This applicationfis a division of my application Serial No. 7 50,927 tiled November 19th,

The salient object of this invention is the production of a waterproof paper in wluch the Waterproofing agent is incorporated into the paper simultaneously with the felting operation. In the drawings ,Y

Figs. 1- lj* and 1 ?taken together indicates a more or'fless Vdia''grammatic showing' of an apparatus-,suitable forjearrying outthe present inventioni Referring'to tlifdrawings, .1' 'designates an emulsify'ing' tankradpted to receive asphalt or other binder, andi-'an emulsifying .agent such as clay and Water. This tankmav be of any suitable construction and sprovided with a rotating shaftv 2 driven through gears 2o .3 and 4,1eadingto any source of power. The shaft 2 carries 'a series of arms cooperatlng with-stationary .arms 6 secured to the side of the'emulsitier. The ob] ect of this emulsifier is to form an emulsiicationl of the binder and emulsfifying agent such as clay, etc. In making this emulsified composition', the clay is putinto the emulsiier and Water is gradually added'until a paste or doughy mixture is obi'tained. Asphalt or other pitchy binder is 'l slowly stirred into this paste and Water .p gradually added from time to time to obl taina Working' consistency. The Water is preferably warm or hot. This mixture is thoroughly beaten up until the binder is uni* formly ydispersed through the emulsifying agent, the object being to reduce the binder to a very line state of division and thoroughly mix it with the clay. lIt is to be understood that other emulsifying agentsthan clay, may be' used and.- in certain cases other 'binder might be usedsuch as hereinafter designated.

This mixture contained in the emulsier can be delivered to a beater 7 through a pipe controlled by valve 9. The beater 7 is of a construction adapted for converting stock into pulp and is provided Awith a suitable beating roll or arms 10 and 11. The pulp which Iuse may be made from any suitable fibrous material such. as paper Waste, tan bark, wood pulp, cotton waste, grassy libres, and hemp. After the fibre is beaten to a pulp, the pulpl is delivered by means of pipes 12 and' 13 and pump 14 to a mixing tank 15. This tank 15 is provided with a mechanical agitator 16 driven from any suitable'source of fpower. The emulsified mixture heretofore re erred to instead of being delivered to the beater 7 may be delivered direct to the mixing tank through. pipe 17'controlled by valve 18.` Ifv the emuls'ified composition is delivered directly to the beater it is closely and thor.- oughly beaten into amalgamation with the pulp, and if it is delivered 'directly' to the mixlnfr tank it is there mixed with the pulp inv suc a way as to thoroughly amalgamatc with the latter'. It will be desirable in many cases to add a filler to the mixture which may be of such relatively cheap materials as saw dust, sand, ground cork or any ,suitable comminuted material.l It may be desirable to less How in the Water so that they will have ,I

opportunities to interlock and interlace with each other when the Water is separated out.;

It is also very important that the materials f be suiiiciently mixed to insure a thorough amalgamation of the fibre with the emulsiied binder and with 'such filler, if a .filler be used. The `materials in question should be so mixed that when in an aqueous solution they Will be free of any tendency to be sticky or adhere to the machine. It may be here noted that when the emulsitied composition is forlned, the particles of the'binder should be so thoroughly and finely dispersed through the aqueous paste that the particles of the binderwill tend to be thoroughly separated from each other and surrounded by the clay and Water. The operator may ascertain that the emulsifieation has been Vsulicient by manualvcmanipulation. If properly emulsitied it will have a smooth, soapy feelingr and be free from any tendency to exhibit adhesiveuess.

After the material is thoroughly mixed it is delivered -to the sheet forming mechanism through pipe 20 controlled by valve 2l. The delivery end of the pipe 20 is provided with a nozzle 22 which is preferably the Width of.

the sheet desired.l The nozzle 22 delivers the mixture to a box 23 which overflows in an endless travelling screen 24.u This screen 24, which may be of a construction similar to those` used in the papermaking industry, may

be a foraminated brass belt which is trained around rollers and 26. Intermediate idler rollers ma be provided as desired. YThe upr lap o the belt travels across rollers 2'( ormin in effect a table or support for the belt. t either side the screen is provided with confining belts 28; it being understood. that these belts serve to prevent the material over the sides of the travelling from flowing sereen.- j A Preferably spreader or distributing rolls 29 and 30 are` provided and theframe s ring gripped as shown at 31. As shown in ig. 1, the apparatus is broken away to reducethe size of the drawings'thev endless screen is of sufiicient length `to allow the desired amounts of water todrainthrou h the screen. cilitate-the removal o the4 Water from the sheet, I provide a pluralityfof suction boxes A i 32 and intermediate pressure rolls 33, a further suetion 34 may be (provided to re.- move further water if desire In forming, the sheet passes over the fo- .raminatedlY belt or screen'into a canvas or l other fabric belt 35, which' is trained aroundV a a series of rolls 36 and driven from any suit-l ablesource of power. Pressure rolls 37 may also be provided. The now formed sheet a is threaded up over the belt 38 to feed rolls 39 and thence up over rolls 40 and 41 to a series of dr ing rolls 42. The -belt 38 serves totake up t e surplus moisture and it is thereafter driedby passing it arqund rolls 43. Y The belt 35 may be cleaned by means of I rotating brushes'34 and suitable water jets 45. The belt 38 canalso be cleaned by brushes 46 and jet nozzle 47, andthe screen 24 by brushes 48 and jet vnozzle 49. It will be understood, however, that one of the important features of the present invention is that vthe-mixture which vis to be sheeted is of such beneath hopper 54 containing suitable granular material so as to 'cover the face ofthe rooting. The sheet' then coated and covered with granular material is .passed between presser rolls and thence over cooling rolls 56 to slitting knives 57 carried by roll 58. The

sheet which is now severed longzitudinallyY may be cut transversely to form shingles or shingle strips by passing through transverse knives 59 carried by rollers 60. It is to be understood of course, thatthese knives and rolls are so geared as to operate synchrodesire la design To fai 'in the conversion of asphalt or other bitunously. The shingles or shingle-strips are then carried away by travelling conveyor belt 61.

-Thahapparatus here shown is adapted for makingshing'lesor shinglestrips of prepared roofing lsuch as asphalt shingles and the like, but itiisgtofbe'gunderstood that the sheetA after been; formed'v may he treated in any man-lin," ch, for example, as having thereon, etc. 's :It may-g4, in certain instancesto put affgranuvlllr inglfover the sheet and dis- "nse` 1vitli'th coating. -'This may be done vgranular material on the sheet t hthhopper 61' while the sheet is `still "havingij2 ins l ciently plastic condition to permit the gdnlar :material to become partially emded inand adhere to the sheet'.I In other cases it may be desirable to give a color or luster to the roofing and this can be accoma5 plished by covering the granular facing of the roofing after it is applied with a film of silica of soda and a igment or d e, the pig-'- ment oidye giving t e desired colbr.

JAn essential feature of this process resides no minous or hydrocarbon material, which is normally of an adhesive nature into a finely divided non-adhesive form. This transformation is accomplished by a process of dispersion of the asphalt into water by means of an emulsifying agent. The, asphalt used is solid or semi-solid at ordinary temperature and is of a character similar to that which is employed for the purpose of waterproofing felts, fabrics and the. like as in the manufacture of repared roofings. The asphalt may either be a native asphalt, ure or containing mineral matter softene if desired,

bymeans of fiuxing oils,-or may be the product 'of distillation or oxidation of asphalt-ic petroleums in a well known manner. It is the nature of such asphalts that, when they are placed in contact at moderate temperatures to coalesce or adhere so'as to form a collo herent and homogeneous mass .and this is an essential characteristic of such asphalts as are used in the manufacture of the stock for particular purposes to be referred to hereinafter. In place of asphalts such as described, I ma also employ tars and pitches of vegetable, anlmal or mineral ori 'n, resins or resinous materials softened, i desired, with tempering oils so as to bring them to the proper consistency for the purpose intended, and such substances are regarded'as comprehended by the term asphalt as employed herein. Heretofore while it has been pro osed to form various-waterproof compoun s containing libresV to be made or produced'in block or sheet form, such materials could not readily be used in connection with the usual web forming machines such as are employed for exampler in the manufacture of felt or paper for the reason that the stock including the contained as- 13 pitchy particles in the web, and the waterproofing of the fibres. Y

While the asphalt herein referred to is designated as being solid or semi-solid at atmospheric temperatures, nevertheless, it is well known that materials of this character are scientifically or more correctly known to be liquids of exceedingly great viscosity, so that while. capable ofbeing handled en masse, nevertheless, they flow slowly at ordinary temperatures and require a containing vessel in order to confine them.' Materials of this character are readil liquifiable by heat, exhibiting a gradual ecrease in viscosity with the elevation of temperature. Such solid or semi-solid asphalts as require the application of heat as distinguished from liquid asphalts are most readily adapted to produce this nonadhesive emulsion. The liquid asphalts, i. e. those capable of being emulsified without the vapplication of heat, while convertible to a relatively non-adhesive form, are neverthe less too easily affected by the pressures employed during the felting operation, so that they become sticky when used on the paper machine. The selection of asphalt of proper character and consistency is therefore an important item in producing the non-.adhesive emulsion. For the purpose of this process as stated before, it is necessaryto convert this adhesive asphalt into a lfinely divided non-adhesive form in which it may be mixed with fibre stock and water and produce a non-adhesive and non-coherent mixture that is capable of lbeing flowed into web form in much the same way that ordinary fibre or paper. stock is caused to form a web.

In paper stock it is necessary, as is well known, to have a sufficient quantity of water in order that the web forming materials may spread themselves in a web, and consequently in any emulsion'which is used for this pur pose it is necessary that the Waterconstitute the external or continuous phase sothat additional Water may be supplied. toform a freely flowing mass, and yet be capable of ex'- traction or expression vwhen the web is produced. So far as I am aware, with the information previously supplied it lhas been 'con'- sidered impossible heretofore to produce an aqueous emulsion of asphalt whlch is nonadhe'sive under the conditions prevailing -in rchine, and it has also been impossible to prepare an emulsion of this character in which has been carried the large amount of asphalt relative to the paper stock which is necessary to lproduce completelyI waterproofed sheet of. felted fibres.' I am aware that emulsions of soaps and resinous materials have been used heretofore for the purpose of sizing paper stock to make it water resistant, but such emulsions have been used under conditions in which the soluble soap employed as an'emulsify'ing agent is reacted upon chemically prior to the formation of the web so as to break the emulsion and precipitate insoluble and more or less non-adhesive soaps or resinates upon the fibres. contemplates the use of no' chemicals or rea' gents which disturb the emulsion or change its non-adhesivecharacter atany stage of the operation prior to the complete removal of wateigi-the transformation from non-ad- The present process hesive to adhesive character of the asphalt y proximating the melting point of the asphalt which is to be emulsified. The asphalt is also -heated until it is quite fluid, the temperature varying with the viscosity of the asphalt and its melting point. Preferably a temperature of 300 to 400 degrees F., isemployed for the harder varieties of asphalt while for the softer varieties va lower temperature affords the desired degree of fluidity; The aqueous suspensionheretoforef referred to is produced in a vessel having means for rapidly agitating the contents thereof. Its consistency 1s such that it is too fluid to hold its form but vsufficiently liquid to flow slowly through a fair' sized orifice. It is important that. the consistency ofthis paste be regulated within morel or less definite limits as the degree of dispersion obtained during the emulsifying operation depends largely upon the viscosity fof the internal friction resulting .1n the agitation of the asphalt throughoutnthe viscous the finer are the resulting particles.

sion. As the asphalt is introduced and continuously emulsified, the mass thickens and it becomes-necessary to add Water in order to maintain the desired viscosity of the contents of the vessel. The addition of asphalt is continued, alternating with the additions of Water and in such quantities as to maintain the desired consistency. If the vessel is sufficiently large, water and asphalt may be added simultaneously in the desired proportions. It is advantageous to maintain the temperature of the asphalt above the boiling point of Water as the expansive force of the steam generated upon contact of' the asphalt with the aqueous suspension produces, by 'more or less foaming, an extension of surface of the pitchy material during its incorporation. The mechanism of this dispersing operation is somewhat as follows: as the asphalt strikes the thick aqueous suspension, it becomes immediately subjected to the agitating arms of the mixer. These arms produce rapid extension and subdivision of the stream of pitch into very fine threads throughout the mass of clay suspension. The viscosity of the thick suspension assists in the formation of these threads and their fine degree of attenuation. At'the Same time the formation of bubbles induced by the steam generated. assists in the production of thin films and threads of the asphaltic material. As these threads are being rapidly formed and rapidly attenuated, a point is reached depending upon the temperature of the mass, its viscosity and rapidity of agitation, at which the threads have become so fine and their surface so great that they become rapidly broken and subdivided into filaments which in turn become subjected to further subdivision until their length is such that their surface tension causes the minute threads thus formed to assume a globular spherical form. This dispersion is produced not only under the conditions and by the mechanical agency above referred to, but also through the presence of the colloid which in effect increases the surface tension of the more or less molten pitch undergoing dispersion or decreases that of the dispersive medium.

As a. result of this operation the asphaltic material referred to becomes dispersed throughout the aqueous suspension into very minute particles. Under the microscope these particles exhibit a spherical or elliptical form depending on the temperature and conditions of dispersion. The more perfect the dispersion, the more nearly spherical and Their size varies. ranging from particles which are probably of colloidal dimensions toy those which can be seen as individual particles With the naked c ve. The average size of the particlesv about .0l millimeter. Some of the smaller particles exhibit distinctive Brownian movement. It should be noted that al- I through the pitch is in liquid condition While being dispersed, the`form of the particles or relation of phases does not change upon cooling and upon more or less hardening or solidification of the pitch in its subsequent reductionto normal temperatures. The emulsion thus formed has the peculiar characteristics of not being affected by electrolytes but precipitates a positively charged colloid as ferrie oxide sol. The emulsion itself is weakly electro-negative. It Will be observed that in the system so produced the asphalt constitutes the dispersed or internal phase While the external or continuous phase comprises the water with the suspended' clay colloid. This constitution of phases with the Water as the external phase permits the dilution or admixture of Water with -the emulsion in all proportions so that when applied 'to the fibre stock the necessary quantities of Water may be added to accomplish the desired Web forming operation. Y y

It is important tonote that a desirable feature in the preparation of this emulsion resides inthe degree of dispersion of the asphalt particles throughout the continuous phase. The fineness of dispersion is to a considerable extent regulated by the viscosity of the mass during agitation and by its tempera- Y ture. For example, if the clay suspension be too thin, and the necessary internal viscosity be lacking, the threads formed during the initial stages of dispersion are relatively coarse,

and the material thus comminuted mav maintain various coarse stages of subdivision ranging from relatively coarse threads down to the finer particles. Likewise if the temperature of either the asphalt or the suspension is too low, coarse particles are similarly formed. OnV the other hand, should the teinperature of the pitch or the partially formed material be too great, there is danger of partial or local coalescence of the previously formed material, due probably to the complete removal of Water by heat from around some of the asphalt particles at the point of confluence with the incoming hot liquid asphalt. Iiurthermore, care should be taken to have sufficient Water present at all times as otherwise the asphalt will agglomerate producing complete inversion of the phase, the Water and clay constituting the internal phase with the asphalt as the continuous medium. The degree of dispersion attained, plays, I believe, an effective part in causing the material to retain its non-adhesive character in the highest and more persistent degree. The process of dispersion` I believe, re-l sults in the formation of heavily absorbed films of Water and clay colloid about the individual particles of asphalt. I believe that the finer the degree of dispersion attained and the greater the surface energy thus resulting, the more tenaciously is this protective. yfilm retained about the particles, so-that in subsetective coating is not. readily broken or disturbed and is only disrupted after the water has been to the largest extent expressed by the 'drying of the sheet.' The larger the particles,

the more easily is this film disturbed in which case s uch larger particles are more readily affected by the pressures employed upon the' paper machine and the greater will be t-he tendency for'the asphalt to become adhesive through the easy removal of the protective coating. I have found when using asphalt of about 140 melting point, .a desirable temperature at which to maintain the clay suspension is about 150 degrees F., and a' satlsfactory temperature at which to carry the asphalt is about 325 to 350 degrees F.,-the

temperature of the batch being maintained during the addition vof the hot asphalt by the `introduction of further quantities of water at a proper heat kto compensate for the tems 'perature of the vincoming asphalt.

When it isdesired to hold the temperature of the batch or bulk supply above 212 degrees F., in order to more advantageously emulsify very viscous materials, such as high melting point oxidized asphalts, the emulsifyirig apparatus is sealed and the entire operation 1s carried on-at pressures above atmospheric;

It is thereby possible dto vmaintain a tempera-` ture above the boiling point of water without permittingevaporation or boiling away of,A

any substantial portions ofwater fromthe apparatus. c i A The non-adhesive character of the emulmaybe roughly followed by manual manipu` lation. A quantity of material when worked between the fingersl should feel smooth,v

grit particles plastic, slippery and free from and should exhlbit no tendency r the particles of asphalt to agglomerate among 'them-l selves when. pressed o rrbbed between the'4 fingers. In fact, the emulsion thus produced should feel substantiallylike the'thickfclay` suspension originally employed -in its -p`rov duction.` It should be readily washed from,l the. hands with water andf'sho'uld be capable` of dilution in all proportions with further quantities of water. If it should be desired to retain the asphalt particles in "suspension,I

to the best possible extent, a protective non- 'adhesive col/leid. may be added after thev emulsification has been completed.

amount of colloidal matter being apablefof carrying the larger. amounts -of asphalt. By

smaller proportions may be employed wherethe amount of asphalt tobe contained in the final paperv productis small and does not contemplate its complete saturation. An analysls of a typical emulsion made by the operatlon above indicated, would show approximately 50% y weight of asphalt10% b y weight of clay and 40% by weight of water. l

I have heretofore describeda batch process for producing this emulsion but I have found where'large quantities are required, that it is most desirable to effect its.manufacture as a continuous operation. For thispurpose, I have provided a mixer or an lemulsifying apparatus provided with helical blades mounted upon a rapidly revolvin shaft. As an initlal stage lnproducing t e emulsion this apparatus is `charged with the aqueous suspenviscosity, asphalt in 'aheated liquid condition is fed into the mass' preferably as it circulates ',downw'ard. lsimultaneously there is fed a sion and its desirable degree of dispersionthin aqueous lsus'pegn'sion of the emulsi-fying agent in Vregulated andpredetermined proportions'cvorresponding ,to the proportions de sired kin thefinal emulsified composition. For example, if an 'emulsion ofthe composition v prtfby; weightgof clay,.an,d four parts by weight ofhw'ater..` l,This ,suspension is fed .to .the emulsifier asy previously described continuously and iny predetermined quantities and csimultaneouslyl with-the introduction of asphalt in like..regulated?quantities.y By regvabove described desired,y the aqueous suspension i'silniaydelup in; proportions of one .ulation .ofthe .volume ofthe incoming streams of asphalt and suspended -gemulsifying agent and by continuous withdrawal of they finished `product-fromt they system,y an .emulsified composition of the character; above described will c beproducednv In order that this emulsion should be cap` In',ll the producing.I i. con;

tinuously, it is limportant to maintain sublstantially similariconditions ,off` viscosity, in^

the,k circulating., mass. of L,finished and surplus emulsion alwayscontained in .the system. Thev retention-of? this quantity lof. surplus emulsion inthesystem acts as a balance wheel against minor j-yafriations rofl viscosity and temperature due gto momentary introduction of excess offeither asphalt or? clayfgsuspension.

It will be evident that on account of auch no emulsion.

i Screens,

minor variations and the necessity for maintaining nearly constant conditions of proportions, temperature and viscosity, it is advantageous to maintain as large a bulk supply of linished emulsion in the system as is compatible with the rate of introduction of incoming ingredients and the withdrawal' of the finished product from the mixer.'

The product of this continuous operation is in all respects the saine as that produced by `batch operation previously described. As taken from the mixer, it is viscid consistency but not so stift` as to prevent its ready egress from the orifice provided for its withdrawal. `As fast as produced this emulsion is preferably thinned with water so as to facilitate its transfer by pumps to the storage tanks and receptacles wherein it is held in suspension for admixture with the paper stock. These tanxs or receptacles in which the emulsion is stored are prefeiably provided with mechanical agitators which serve the purpose of maintaining a uniform suspension of the asphalt throughout the aqueous medium.

In the manufacture of paper by means of this process the stock is prepared in the usual manner by beating, jordaning and screening. Various stocks may be used such as sulphite, sulphate, rag fibres, mixed papers,- mechanical wood, leather, to which if desired, may be added sawdust. In some instances after the stock has been thoroughly beaten'out, the emulsion may be pumped directly into the beaters and circulated with the stock until a uniform mixture is obtained; or an emulsion may be added in the stuff chest and likewise subjected to suitable agitation to provide a uniform mixture. j I have generally found it preferable, however, to mix the emulsion with the fibre stock at the mixing box interposed between the machine chest and the The proportion of emulsion to stock is readily controlled by valves on the delivery line or by usual metering devices and its introduction at this point facilitates rapid and easy variation of proportions. The mixture thus produced is preferably kept cold and passes through the screens and to the fiow box of the machine whence it is formed into a sheet, exactly as if the stock contained A cold mixture produced by mechanical refrigeration, if desired, affects favorably the non-adhesive qualities of the emulsion and assists its resistance to pres-- sure during sheet forming operation. The sheet or web is' formed in the usual manner by felting or interlocking with the fibres on either cylinder or screen Ldepending upon the type of machine, the sheet being successively subjected to the action of suction boxes, press l end of the machine, the asphalt particles retain their adsorbed films of water with protecting colloid to such an extent that the sheet or stock is at all times non-adhesive. Upon reaching the dryers, the residual moisture is gradually removed yand the asphalt particles under the influence of heat and removal of adsorbed films of water gradually coalesce forming a more or less continuous phase throughout the sheet. When operating with a multi-cylinder machine, it is of course possible tovary the quantity and character of the emulsilied asphalt in any of the plies; for example, the outer plies maybe composed of ordinary rosin size stock free from asphalt, or may have introduced a colorable pitch while the body plies of the sheet may contain the usual quantity of black asphalt; likewise, under such conditions it is possible to use a softer asphalt of the same character in the body plies while employing a relatively hard and high melting point asphalt for the outer plies. It will be apparent that wide variations in character of the resulting product may be effected under such conditions producing thereby sheets which are particularly adaptable for special uses in which waterproof boards or heavy papers can be applied.

The product of this process is further characterized by the additional strength in the resulting sheet over that possessed when the lstock itself is formed into a` corresponding unsaturated sheet. The strength is increased almost directly in proportion to the amount of asphalt introduced. This affords an additional advantage in the roofing art wherein a product of this character containing less than the full saturation may be subsequently subjected to the usual process of tank saturation to take up additional amounts of asphalt and complete its saturation. A product of this character referred to, on account of its additional strength can be run through the machine with great rapidity and has the properties of absorbing additional saturation with great readiness.

It has heretofore been impossible to under-saturate or partially saturate a sheet of dry felt by tank method for the reason that saturation proceeds from the outer surfaces of the sheet and if the sheet is not permitted to take on its full saturation, it will be foun that although the outersurfaces are completely saturated, the inner body of the paper may remain entirely free from vthesaturating liquid. A product of this process when incompletely saturated differs in this respect. The coa-lescence of the individual particles of asphalt and their ability to coat the individual fibres constitutes a novel feature of the behavior of the stock thus produced, on the driers. Even though the amount of aspha t maintained in the sheet be considerably l ss than that required to produce full saturation, the asphalt contained therein is uniformly distributed vou appearance due more or less-:go

A a surface partially deprived;

- small proportions, may maintain the' of the sheet as a more orless ing upon the fibres. the body of the sheet, I lr surface may under some` apparently as a result off'tor sucking from the Surfa belngformed. In such cases ell face or superficial areas mayfsh of the asphalt as above desci'il) applications of this proces valuable feature of the inv stance, in the case of iotig-coyI ings i are to be painted with a'decoratiyfie eoagtng It has heretofore been found ffii l plying such paint coatingsl to rated felt, to prevent the aspv u coming dissolved into the paint n y, ing it. The product of this inge v01 P affords an ideal surface'upon which with decorative paint. I have described a drying operati usually carried on in connection-auth inder or Fourdrinier type of which a drying temperature is. the boiling point of Water and the drying operations in such a Wayjthatlthe particles of asphalt, especially When: u in l diss crete form and serve the function ofrtying together and reinforcing the fibres and acting as a water repelling agent. Forge ample, the product of this process produced"y on a wet machine may be dried in a drying room at a relativelylow temperature and by proper` selection of temperature with relation to melting point of asphalt employed, a dry sheet may be obtained in which the asphalt particles maintain their individual form, serving the purposes above described.

It will be further noted that the adhesive character of the asphalt is resumed during the drying operation and is attained only byl the removal of Water and by heat and without the use of chemicals or-reagents to convert it to altered form. This result-is accomplished by the purely physical means de-l yscribed.

I'have discovered also that a valuable feature ofthe invention resides in the fact that v the addition of the asphalt emulsion as be- 'fore described to the paper stock, causes the formation without interferingvvith the feltthe body of the sheet may containtheasphalm uniformly distributed throughput,

Q; aslllere-fatore sufficient to l L cause complete coalescence of theindividual. particles of asphalt into a continuous,.filnr.

have found it possible, however, tofCOIld-llt 'i caches thefjdriers, and :the asplialtparticles l K coalesce and spread themselves about he fibres-in thin films,'it isapparent that u he spacing produced byy theiroriginal p omore or less freed from the-asp ltl'par cilesz/itlonresults 1n asheet-having:greater void -spaces; and being,lin fact, bullied, it follows that the greater v yardage of papelresults irvmthis bulli lng f1:01 11 a given quantity 0f teck. I havefounihina ertain instances that his ,bulking :hasfnrodud.as-milch es 00% ncree imiter @yardage-0f panel' 0M-er @and l abovertlw@ quantitaanfodlwd linfihe. usual,

9fans .te employ @felis orgieltedfnalwrecome rgely "of, rag fibresfg .This has4A been y'iorf tlie;1@ae11fthat; suchte/lts "Only e5 lca able of j;

introduction o even smal, ies ,of othery S1011" Sulati-:vely i man" sheetwhich is practically completely saturated 110 l with asphalt and in character not -readil distingulshable from tank saturated felt. sheet of-product derived from the above for- `mula and in fact any productof this process,

sforined v tion-,and it t tanksatnrithe l ,at pentita 165' f will upon extraction with suitable solvent for asphalt, leave a sheet of dry paper likewise indistinguishable from paper formed in the usual manner. While the proportions above stated produce a substantially saturated sheet, it is desirable jin many instances and for many 4purposes to produce a. sheet less completely saturated as for example for Hoo-rlng felt, for wrapping papers, lining papers, shoe elements and the like. An example of -the formula for partly saturated stock may 1.25

be given as follows: to 50% of paper stock of dry weight is added an emulsion composed of 35 parts by weight of asphalt withfl parts l by weight of colloidal clay'containedin its aqueous vehicle.v This wllproduce a stock suitable for damp proof papers and by proper yselection lof the paper stock constitutes a composition :suitable for formation into shoe elements such as counters and the like. It should be noted as a novel-feature of this process that the amount ofasphalt and non-fibrous mate- .rial which can be carried by the fibreswith- ,out interfering with the felting operation inaybe more than twice the Weight of fibres used. This I believe, constitutes a radical departure from any heretofore known practices of producing paper which permits of the introduction of so large a quantity of nonfibrous material Without interference with the sheet forming or felting operation.

I have found that the use of this emulsion in stock -has a tendency during formation of the web to close up the sheet and result in some difficulty when it is desired to produce a heavy caliper in a single ply. In such instances, I have found that the introduction of a small quantity of sawdust affords the necessary freeness to enable the sheet to be built into relatively thick calipers with easy removal of the Water.

I claim as my invention:

l. A process of producing a waterproofed felted sheet, comprising mixing in Water fibrous stock and a dispersion containing a heat liquifiable Waterproofing material dispersed in an aqueous medium, regulating the proportions of fibrous kstock relative to said waterproofing material so as to produce 'a sheet Which is incompletely saturated with o said Waterproofing material, but in which said Waterproofing material is substantially uniformly distributed in the form of substantially continuously coalesced films about the fibers, sheeting said stock, and drying the sheet.

2. A process of producing a waterproofed felted sheet, comprising mixing in water fibrons stock and a dispersion containing a incassa.

heat liquifiable Waterproofing material dispersed in an aqueous medium, regulating the proportions of fibrous stock relative to said Waterproofing material whereby the fibrous constituents of the sheet so formed predominate, on the basis of Weight, relative to the non-fibrous constituents, the Waterproofing material being present in such an amount as "to be substantially uniformly distributed about the fibers in the form of substantially continuously coalesced lms, sheeting said stock, and drying the sheet.

3. A Water resistant felted fibrous sheet containing Waterproofing material distributed substantially uniformly about the fibers in the form of films, said sheet having the Acharacteristics of having had Waterproofing material incorporated during formation thereof and Waterproofing material converted in the form of substantially continuously coalesced'films, and further characterized in that the Waterproofing material, on the-basis of Weight, is less than the fibrous stock.

4. An asphalt containing fibrous sheet having greater quantity, on the basis of Weight,

of fiber relative to asphalt, characterized by having had the asphalt incorporated therewith during formation of the sheet, said asphalt being distributed uniformly about the fibers in the form of substantially continuously coalesced films constituting an unbroken Waterproofing medium.

5. An asphalt containing fibrous sheet,

characterized by having had the asphalt incorporated therewith during formation of the sheet, said asphalt being distributed uniformly about the fibers in the form of substantially continuously coalesced films, said sheet being further characterized by containing a substantial amount of said asphalt, but

less than the amount of fiber, on the basis of Weight.

LESTER KIRSCHBRAUN.

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