US1615303A - Process of making bituminous emulsions - Google Patents

Description

3 Sheets-Sheet- 1 n, 2 i927@ Ea 5 9 L.. KLRSCHBRAUN PROCESS OF MAKING BITUMINOUS EMULSNS Filed Nov. 2l. .1919

magos A e v 192K Hm 25 L. KlRscl-IBRAUN PROCESS OF MAKING' BITUMINOUS EMULSIONS 3 Sheets-Sheet 2 Filed Nov. 2l, 1919 L. KIRSCHBRAUN Pnocss oF MAKING BITUMINous EMULsloNs Filed Nov. 21, l1919 s sheets-sheet s Patented Jan. v25, 1927.

PATENT OFFICE.

LESTER XIRSCHIBRAUN,l F CHICAGQ, ILLINIS.

P ROCESS 0F MAKING BITUMINOUS EMULSIDNS.

Application tiled November 21, 1919. Serial No. 389,690.

The present invention resides in a process of makin emulsions of the bitumen-pltch type in w ich the temperature of the mass undergoing dispersion is maintained at such a oint that the bitumen-pitch type base wiil be dispersed without a substantial amount of coalescence.

In the drawings:

Figs. v1, 1A and 1B taken together indicate a more or less diagrammatic showing of an apparatus suitable for carrying out the present invention.

Referring to the drawings, 1 designates an emulsifying tank adapted to receive asphalt or other binderaand an emulsifying agent` such as clay and water. This tank may be of any suitable construction and is provided with a rotating shaft 2 driven through gears 3 and 4, leading to any source of power. arms 5 (zo-operating with stationary arms 6 secired to the side of the emulsier. The obje t of this emulsifier is to form an emulsication of the binder and emulsifying agent such as clay, etc. In making this emulsified composition, the clay is put into the emulsitier and water gradually added until a paste or dougliy mixture is obtained.- Asphalt or other 'pitchy binder is then slowly stirred into this paste and water' is gradually added from time to time to obtain a working consistency.- The water is preferably warm or liot. This mixture is thoroughly beaten up until `the binder is uniformly dispersed through the emulsifying agent, the object being to reduce the binder to a very fine state of division and thoroughly mix it with the clay. It is to be understood that other emulsifying agents than clay, may be used and in certain cases other binder might be used such as hereinafter designated.

This mixture contained in the emulsier can be delivered to a beater 7 through pipe 8 controlled by valve 9. The beater 7 is' of a construction adapted for converting stock into pulp and is provided with a suitable beating roll or arms 10 and 11. The pulp .vhicli I use may be made from any suitable fibrous material such as paper waste, tan bark, wood pulp, cotton Waste, grassy fibres, and hemp. After the fibre is beaten to a pulp, the pulp is delivered by means of pipes l2 and 13 and pump 14 to a mixing tank 15. This tank is provided with a mechanical agitator 16 driven from any suitable source of power. The emulsified mixture hereto- The shaft 2 carries a series offore referred to instead of being delivered to the beater 7. may be delivered direct to the mixing tank through pipe 17 controlled by valve 18. If the emulsified composition is delivered directly to the beater it is closely and thoroughly beaten into amalgamation with the pulp, and if it is delivered directly to the mixing tank it is there mixed with the pulp in such a way as to thoroughly amalgainate with the latter. It will be desirable in many cases to add a filler to the mixture which may be of such relativel cheap ma terials as saw dust, sand, groun cork or any suitable comminuted material. It may be desirable to add more clay to the mixing tank also. The mixture in the tank 15 is thinned to the desired consistency by adding as much water as desired through the pipe 19.. The consistency of the mixture in the mixing tank will depend upon the character of the product to be formed yand also upon the character of the materials in the mixing tank. In the formation of roofing compositions, the mixture, I have found in certain cases, should be sufficiently diluted with water to permit the fibres to more or less How in thegwater so that they will have opportunities to interlock and interlace with each other when the water is separated out. It is also' very important that the materials be suiciently mixed to insure a thorough amalgamation of the librev with the emulsified binder and with such filler, if a filler be used. The materials in question should be so mixed that when in an aqueous medium they will be free of any tendency to be sticky or adhere to the machine. It may be here noted that when the emulsified composition is formed, the particles of the binder should be so thoroughly and finely dispersed throu h the aqueous paste that the particles of t e binder will tend to be thoroughly separated from each other and surrounded by the clay and water. The operator may ascertain that the emulsilication has been suicient by man-- -ual manipulation. If pro erly emulsiied it with nozzle 22 which is preferably the widthof the sheet desired. The nozzle 22 delivers the mixture to a box 23 which overflows into an endless travelling screen 24. This screen 24 which may be olI a construction similar to those used in the paper making industry, or may be a i'oraminated brass belt which is trained around rollers 25 and 26. Intermediate idler rollers may be provided as desired. The upper lap of the belt travels across rollers 27 forming in eiicct a table or support for the belt. At either side the screen is provided With confining belts 28; it being understood that these belts serve to prevent the material from flowing over the sides of the travelling screen.

Preferably spreader or distributing rolls 29 and 30 are provided and the frame spring gripped as shown at 31. As shown in Fig. l, the apparatus' is broken away to reduce the size of the drawings, the endless screen is of suhcient length to allow the desired amounts of Water to drain through the screen. To facilitate the removal of the water from the sheet, I provide a plurality of suction boxes 32 and intermediate, pressure rolls 33, a further suction pipe 34 may be provided to remove further Water if desired.

In forming the sheet passes over the foraminated belt or screen onto a canvas or other fabric belt 35, which is trained around a series of rolls 36 and driven from any suitable sourceof power. Presser 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 4l to a series of drying rolls 42. The belt 38 serves to take up any surplus moisture and it is thereafter dried by passing it around rolls 43.

The belt 35 may be cleaned by means of rotating brushes 44 and suitable Water jets 45. The belt 38 can also be cleaned by brushes 46 and jet nozzle 47, and the screen by brushes 48 and jet nozzle 49. It will be understood, however, that one of the important features of the present invention is thatl the mixture which is to be sheeted is of such character that it can be` readily washed oit of the various belts and will not stick thereto.

After the now formed sheet leaves the rolls 42 it passes through rolls 50 to the coating mechanism 51, which is provided with delivery pipe 52.for the coating material, and presser rollers 53 which may be of any suitable construction. If granular faced roofing is being formed, the coated sheet can be fed beneath hopper 54 containing suitable granular material so as to cover the face of the roofing. The sheet then coated and covered with granular material is passed between presser rolls 55 and thence over cooling rolls 56 to slitting knives 57 carried by roll 58. The sheet which is now severed longitudinally may be cut transversely to form shingles or shingle strips by passing through transverse knives 59 carried by rollers (it). lt is to be understood ol course (hat these knives and rolls are so geared as to operate synchronously. The shingles or shingle strips are then carried away by travelling conveyor' belt 61.

The apparatus here shown is adapted for making shingles or shingle strips of prepared rooting suoli as asphalt shingles and the like, but it is to be understood that the sheet after having been formed may be treated in any desired manner, such for cxample, as having a design printed thereon, etc.

It may be desirable in certain instances to put a granular facing over the sheet and dispense with the coating. This may be done by impressing granular material on the sheet through the hopper 61 While the sheet is still in sufficiently plastic condition to permit the granular material to become partially embedded in and adhere to the sheet. ln other cases it may be desirable to give a color or luster to the roofing and this can be accomplished by covering thegranular facing of the rooting after it is applied with a tlm of silica of soda and a pigment or dye, the pigment or dye giving the desired color.

An essential feature of this process resides in the conversion of asphalt or other bituminous or hydro-carbon material, which is 9 normally of an adhesive nature into a finely divided nonadhesive form. This transfermation 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 prepared rootings. The asphalt may either be a native asphalt, pure or containing mineral mattei' softened, if desired, by means of fluxing oils, or may be the product of distillation or oxidation ,of afcphaltic petroleums in a well known manner. It is the nature of such asphalts that when they are placed in contact at moderate temperatures they coalesce or adhere so as to form a coherent 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 mair also employ tars and pitches of vegetable, animal or mineral origin, resins or resinous materials softened. il' desired, with tempering oils so as to bring them to the proper consistency for the purpose intended, and such substances are re` garded as comprehended by the terni bitu' men or bitumen-pitch type base as cmployed in my claims. Heretofore While il has been proposed to form various waterproof compounds containing libres to be made or produced in block or in sheet form.,

suchmaterials could not readily be used in connection with the usual web forming nachines such as are employed for example in the'manufacture of felt 0r paper for the reason that the stock including the contained asphalt was of such an adhesive nature as to cause the gumming of the machinery and blankets. Of course if the pitch be of such solidity at ordinary temperatures that il 1s capable of being ground or comminuted like gilsonite it may be mixed with libre just as particles of charcoal are mixed, but in that event such pitchy particles are not adhesive at ordinary temperatures at which the stock is maintained when the web is being formed into paper, and the subsequent evaporation of the water or subjection of the web to pressure would not cause the coalescence of the pitchy particles in the web, and the Waterproofing of the fibres.

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 characterl 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 readily liquefiable by heat, exhibiting a gradual decrease in viscosity with the elevation of temperature. Such solid or semisolid asphalte as require the applicationof heat as distinguished from liquid asphalts are most readily adapted to produce this non-adhesive emulsion. The liquid asphalts, i. e., those capable of being enlulsified without the application of heat, while convertible to a relatively non-adhesive form, are nevertheless easily affected by lthe pressures employed during the felting operation and are likely to become sticky under certain conditions When used on the paper machine. The selection of asphalt of proper character and consistency is an important item in producing the non-adhesive emulsion. For the purpose of this process as stated before, it is necessary to-convert this adhesive asphalt into a finely divided nonadhesive 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 being 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 vin any emulsion which is used for this purpose it is necessary that the water constitutethe external or continuous phase so that additional Water may be supplied to form a freely flowing mass, and yet be capable of extraction or expression when the web 1s produced. So far as I am aware, with the information previously supplied it has been considered impossible heretofore to produce an aqueous emulsion of asphalt which is nonadhesive under the conditions prevailing in heating stock and under the pressures employed in forming a web on the paper machine, 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 produce completely Waterproofed sheet of felted fibres. I am aware that emulsion 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 an emulsifying 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 Ior resinates upon the fibres. The present process contemplates the use of no chemicals' or reagents which disturb the emulsion or change its non-adhesive charac- 4ter at any stage of the operation prior to the complete rem-oval of Water; the transformation from non-adhesive to adhesive character of the asphalt being accomplished 'only by the removal of Water, through the application of pressures or heat, or both.

In order to produce the emulsion above referred to, I use clay containing a large proportion of colloidal material as an emulsifying agent but obviously other finely divided powders or colloidal materials which produce an emulsion of a non-adhesive character may be used in lieu thereof.

Among the other finely divided powders which may be used Within the contemplation of the present invention, may be cited fullers earth, mineral pigments, slate dust, ochre, sienna, metallic oxides and hydroxides, and silicates, which produce a viscous plastic mixture with water.

The emulsion may be produced in batches or by a continuous process. If prepared as a batch, I first make a thick aqueous suspension of the clay and heat it to a temperature approximating 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 o f the asphalt and its melting point. Preferably a temperature of 300 to 400O F. is employed for the harder varieties of asphalt While for the softer varieties a lower teinperature affords the desired degree of fluidity. The aqueous suspension heretofore referred to is produced in -a vessel having means for rapidly agitating the contents thereof. Its consistency is such that it is too fluid to hold its form but sulliciently viscous to flow slowly through a fair sized orifice. lt is important that the consistency of this paste be regulated Within more or.

less definite limits as the degree of dispersion obtained during the emulsifying opera tion depends largelyv upon the viscosity or the internal friction resulting in the agitation of the asphalt throughout the viscous clay suspension.

The molten asphalt is gradually added to the viscous suspension While the lnass in the vessel is being subjected to rapid agitation. This is important in order to avoid inversion of phase and production of an adhesive emulsion. As the asphalt is introduced and continuously emulsified the mass thickens and it becomes necessary to add Water in order to n'iaintain the desired viscosity of the contents of the vessel. The addition of asphalt is continued, alternating Wit-h the additions of Water and in such quantities as to maintain this desired consistency. If the vessel is sufficiently large Water and asphalt maybe added simultaneously in the desired proportions. lt is advantageous in some cases to introduce the asphalt at a temperature above theiboiling 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 theA agitating arms of the mixer. These arms-produce rapid extension and sub-division 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 tine degree of attenuation. At the same time the formation of bubbles induced by the steam generated1 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 or 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'v undergoing disdividual particles with the naked eye. The

average size of the particles is about .0l millimeters. Some of the smaller particles exhibit distinctive Brownian movement. It should be noted that although the pitch is in liquid condition When introduced, the form of the particles or relation of phases docs not change upon cooling and upon more or less hardening or solidcation of the pitch laits subsequent reduction to no1'- mal temperatures. The emulsion thus formed has the peculiar characteristic of not being affected to the point of rupture by electrolytes but precipitates a positvely charged colloid ferrie oxide sol. The emulsion itself is weakly electro-negative. It. Will be observed that in the system so produced the asphalt constitutes the disperse 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 thc emulsion in all proportions so that when applied to the fibre -stock the necessary quantities of water ma be added to accomplish the desired We forming operation.

lt is important to note that a desirable feature in the preparation of this emulsion resides in the degree of dispersion of thc asphalt particles throughout the continuous phase. The fineness of dispersion is to a considerable extent regulated by the viscosity of the mass, which if it is desired to keep it fine, should be relatively thick or pastelike, during agitation and by its temperature. 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 may maintain various coarse stages of subdivision ranging from relatively coarse threads down to the finer particles. Like- Wise if the temperature of either the asphalt or the suspension is too low, coarse particles are similarly formed. On the other hand should the temperature of the pitch or the partially formed material be too great, there is danger of partial or local i coalescence 'off the previously formed ma- 1 coating.

'of about 140 melt-ing point, a desirable temterial, due probably to the complete removal of water by heatfrom around some of the asphalt particles at the point of confluence with the incoming hot liquid asphalt. Furthermore care should be taken to have sufficient water present at all times as otherwise the asphalt will agglomerate producing complete inversion ot' 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 eii'ective part in causing the material to retain its non-adhesive character in the highest and most persistent degree. The process of dispersion, I believe, results 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 tilm retained about the particles, so that in subsequent operations of forming paper, this protective coating is not readily broken or disturbed and is only disrupted after the water has been tothe largest extent expressed by the drying of the sheet. The larger the particles, the more easily is this film disturbed in which case such larger particles are more readily aHected by the pressures employed upon the paper machine and the greater will be the tendeney for the asphalt to become adhesive through the easy removal of the protective I`have found when using asphalt perature at which to maintain the clay suspension is about 150 F. and a satisfactory temperature at which to carry the asphalt is `about 325 to 350 F., the temperature of the batch being maintained during the addition of the hot asphalt by the introduction of further quantities of water at a proper heat to compensate for the temperature oi' the'incoming asphalt.

lVhen it is desired to holdthe temperature of the batch or bulk supply above 212 F., in order to more advantageously emulsify very viscous materials such -as high melting point oxidized asphalts, the emulsifying apparatus is sealed and the entire operation is carried on at pressures above atmospheric. It is thereby possible to maintain a temperature above the boiling point of Water without permitting evaporation or boiling away ot' any substantial quantities of water from the apparatus.

The non-adhesive character of the emulsion and its desirable degree of dispersion may be roughly ascertained by manual manipulation. A quantity ot material when worked between the fingers should feel smooth, plastic, slippery and free from grit'I particles and should exhibit no tendency for the particles of as halt to agglomerate among themselves W en pressed or rubbed between the fingers. In fact, the emulsion thus produced should feel substantially like the thick clay suspension originally employed in its production. It should be readily washed from thel hands With water and should be capable of dilution in all proportions with further quantities of water. If it should be desired to retain the asphalt particles in suspension to the best possible extent, a protective non-adhesive colloid may be added after the emulsiication has been completed.

In order that this emulsion yshould be` capable to the greatest possible extent of being carried in large lquantities by the fibrous stock, it is desirable that the proportion of asphalt to clay be large. The amount of asphalt Which-can thus be emulsified depends considerably upon the clay, apparently varying with the amount of colloidal matter in such clay; thus. clays carrying the largest, amount of colloidal matter being capableof carrying the larger amounts of asphalt. By using the proper quality of clay I have been able to make an emulsion containing as much' as ten parts of asphalt, by weight, to one part of clay. Ordinarily, however, portions of four or five'parts of asphalt to one part of cla will be found most satisfactory althoug smaller proportions may be'employed where the amount of asphalt to be contained in the linal paper product issmall and does not contemplate its complete saturation. An analysis of a typical emulsion made by the operation above indicated would show approximately 50%, `by weight, of asphalt,'

10%,b weight of clav and 40%,by wei ht y a y g a ,of water.

I have heretofore described a batch pfocess for producing this emulsion but I have found Where large quantities are required, that it is most desirable to effect its ina-nufacture as a continuous operation. For this purpose, I have provided a mixer or an emul sifying apparatus provided with helica. blades mounted upon a rapidly revolving shaft. In an initial stage of producing the emulsion this ,apparatus `is charged with the aqueous suspension or with finished product as before described for batch operation. The

agitation blades are so disposed as to cause a rapid incorporation of liquids introduced at the top of the vessel with the bulk contents of the container.

vAfter the initial charge of suspension or,

mined proportions corresponding to the pro-I Y desired, may be added sawdust.

instances after the stock has been thorough-A portions desired in the final emulsified composition. For example, if an emulsion of the composition above described is desired, the aqueous suspension is made up 1n proportion of one part, by Weight, of clay and four parts, by weight, of Water. Thissuspension is fed to the emulsifier as previously described continuously and in predetermined quantities and simultaneously with the introduction of asphalt in like regulated quantities. By regulation of the volume of the incoming streams of asphalt and suspended emulsifying agent and by continuous withdrawal of the finished product from the system, an emulsified composition of the character above described Will be produced.

In the producing of emulsion thus continuously it is important t0 maintain substantially similar conditions of viscosity in the circulating mass of finshed and surplus emulsion always contained in the system. The retention of this quantity of surplus emulsion in the system acts as a balance wheel against minor variationsof viscosity and temperature due to momentary introduction of excess of either asphalt or clay suspension. It will be`evident that on account of such 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 finished 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 same as that produced by batch operation previously described. As taken from the mixer, it is of viscid consistenc)Y but not so stiff as to prevent its ready egress from the orice 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. rl`hese tanks or receptacles in which the emulsion s-stored are preferably 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 In some l v beaten out the emulsion may be pumped directly int'o 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. 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 screens. 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 How box of the machine whence it is formed into a sheet, exactly as if the stock contained no emulsion. A cold mixture produced by mechanical refrigeration, if desired, affects favorably the nonadhesive qualities otl the emulsion and assists its resistance to pressure 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 depending upon the type of machine, the sheet being successively subjected to the action of suction boxes, press rolls and after the desired amount of water is removed transferred in the usual way to the dryers. During the entire time and at all stages of the passage of the stock over the Wet end of the machine, the asphalt particles retain their adsorbed iihns 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 and 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. lvhen operating with a multicylinder machine, it is of course possible to vary the quantity and character of the emulsified ashpalt in any of the plies; for example the outer plies may be composed of ordinary rosin size stock free from asphalt or may have introduced thereinto a colorable pitch while the body plies of the sheet may contain the usual quantity of black asphalt; likewise, under suc-h conditions it is possible to use a softer asphalt of the same character in the body plies while embodying 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.

rIhe product of this process is further characterized by the additional strength in the resulting sheet over that possessed when the stock itself is formed into a corresponding unsaturated sheet. rl`he 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 subsequently be 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.

lIt has heretofore been impossible to undersaturate 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 found that although the outer surfaces are completely saturated, the inner body of the paper may remain entirely free from the saturating liquid. A product of the present process when incompletely saturated di'ers in this respect. The coalesceuce 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 dryers. Even though the amount of asphalt maintained in the Asheet be considerably less than that required to produce full saturation, the asphalt colitained therein is uniformly distributed throughout the body of the sheet as a more or less continuous coating upon the libres. While this is true of the body of the sheet, I have found that the surface may under some conditions become more or less freed from the asphalt particles apparently as a result of their washing off or sucking from the surface as the Web is being formed. In such cases although the body of the sheet may contain the asphalt uniformly distributed throughout, the surface or superficial area may show a mottled appearance due more or less to the removal of the asphalt as above described. In certain applications of this process, this affords a valuable feature of the invention, as for instance, in the case of floor coverings which are to be painted with a decorative coating. It has hereto-- fore been found difficult in applying such paint coatings to ordinary saturated felt, to prevent the asphalt from becoming dissolved into the paint and discoloring it. The product of this invention, with a surface partially deprived of asphalt affords an ideal surface uponV which to print with decorative paint.

I have usually carried on in connection with the cylinder or Fourdrinier type of machine in which a drying temperature is used above the boiling point of water and sufficient to cause complete coalescence of the individual particles of asphalt into a continuous film.

I have found it possible, however, to conduct the drying operations in such a way that the described a drying opera-tion as is A particles of asphalt, especially when used 1n small proportions, may maintain their discreet form and serve the function of tying together and reinforcing the fibres and ,acting as a water repelling agent. For 'example, the product of this process produced on a wet machine may be dried in a drying room at a relatively lowftemperature and by proper selectionl 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 isattained only by 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 b v the purely physical means described. 4

I have discovered also that a valuable' feature of the'invention resides in the fact that the addition of the asphalt emulsion as before described to the paper stock, causes the fibres in their formation to be somewhat bulked; that is to say the particles of asphalt seein to have the tendency to separate lthe fibres from each other to some extent during formation without interfering With the felting operation. Vhen the sheet thus formed reaches the dryers and the asphalt particles begin lto coalesce andspread themselves about the fibres in thin films, -it is apparent that the spacing'produced luy-their origlnal position results in a sheet having greater void spaces; and being, in fact, bulked, it follows that greater yardage of paper results from this bulking froma given quantity of stock. I have found in certain instances that this bulking has produced as much as 60% increase in area or yardage of paper over and above the quantity produced in the usual manner, from an equivlent weight of fibre stock. l

In the preparation of saturated felt as for roofing fabrics, it'has been the practice heretofore to employ feltsor felted papers composed largely of rag fibers. This has been necessary for the reason that such felts only appear capable of saturation by im-i mersion in the hot asphalt in a well known manner. The introduction of even small quantities of other'pa'per stocks such as sulphate news or sulphite substantlally r'etards saturation and 1t has heretofore been impossible to satisfactorily saturate felts composed of such stocks. By my process, however, all such limitations are obviated and I may readily use such socks as heretofore have not been usable in tank saturated fe'lts. These stocks are relatively cheap and their use results in great economy over the production of saturated felts by heretofore*l known processes.

As an example of proportions used in the practicing of this invention, I take thirty parts, by Weight, of dry libre stock which may be any of the varieties of stock heretofore n'icntioned and mix with this, after beating out and while contained as a watery pulp, a mixture comprising lifty-eightparts of asphalt emulsilied with twelve parts, by weight, of clay contained in its aqueous; vehicle. This proportion of components will produce a sheet which is practically completely saturated with asphalt and in character not readily distinguishable from tank saturated felt. A sheet of product derived from the above formula and in fact any product of this process, will upon extraction with suitable solvent for asphalt, leave a sheet of dry paper likewise indistinguishable from paper formed iu the usual manner. lVhile the proportions above stated produce a substantially saturated sheet, it is desirable in many instances and for many purposes to produce a sheet lexis completely saturated as for example for flooring felt, for wrapping papers, lining,r papers, shoe elements and the like. An example of the formula for partly saturated stock may be given as follows: To 50% of paper stock of dry weight is added an emulsion composed of 35 parts by weight of asphalt with 15 parts by Weight of colloidal clay contained in its aqueous vehicle. This will produce a stock suitable for damp proof papers and by proper selection of 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 vof this process that the amount of asphalt and non-fibrous material which can be carried by the fibres without interfering with the felting operation may be 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' non-fibrous 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 lto be built into relatively thick calipers with easy removal of the water.

Iclaim as my invention:

l. The process of producing an emulsion which comprises adding a bitumen in a fluid state to a mixture of clay and water While agitating said mixture and maintaining its temperature at such a point that the bitumen will be dispersed without a substantial amount of coalescence of the same.

2. The process of producing an emulsion which comprises adding a bitumen in a fluid state to a mixture of clay and Water while agitatiug said mixture and maintaining its temperature at such a point that the bitumen will not coalesce but Will disperse.

3. rlhe process of producing an emulsion which comprises adding a hot bitumen in a fluid state to a mixture of clay and Water while agitating said mixture and maintaining its temperature at such a point that the bitumen will be dispersed without a substantial amount of eoalescence of the same.

4. The process of producing an emulsion which comprises adding asphalt in a fluid state to a mixture of clay and water While agitating said mixture and maintaining its temperature at such a point that the asphalt. will be dispersed without a substantial amount of coalescence of the same.

5. rl`he process of producing an emulsion which comprises adding hot asphalt in a fluid state to a mixture of clay and Water while agitating said mixture and maintaining its temperature at such a point that the asphalt will be dispersed without a substantial amount of coalescence of the same.

6. A process of producing an emulsion which comprises dispersing a bitumen-pitch type base in a fluid state in the presence of a mixture of dispersive media and water u'hile agitating said mixture, and maintaining its temperature at such a point that the bitumen-pitch type base will be dispersed without a substantial amount of coalescence of the same.

7. A process of producing an emulsion which comprises dispel-sing a bitumen-pitch type base in a fluid state in the presence of a mixture of mineral dispersive media and water while agitating said mixture, and maintaining its .temperature at such a point that the bitumen-pitch type base will be dispersed without a substantial amount of coalescence of the same.

8. A process of producing an emulsion which comprises dispersing a bitumen-pitch type base in a fluid state.in the presence of a mixture of finely divided powder-like material and water While agitating said mixture, and maintaining its temperature at such a point that the bitumen-pitch type base will be dispersed without a substantial amount of coalescence of the same.

9. A process of producing an emulsion which comprises dispersing a bitumen-pitch type base in a fluid state in an aqueous medium by subjecting same to agitation in the presence of a mineral dispersive media in aqueous suspension, and regulating the fineness of dispersion by controlling the viscosity of the mass during agitation and lill) maintaining the temperature at such a point that the bitumen-pitch type base will be distype base in a1 fluid state in an aqueous inc- I that the bitumen-pitch type base will be dis-v 'low that at which dium by subjecting same to agitation in the presence of a mineral dispersive inedia tak-l ing the form ofi-finely divided powdery niaterial in aqueous suspension7 and regulating the fineness of dispersion by controlling the viscosity ofthe mass duringagitation, and maintaining the temperature at such a point that the bitumen-,pitch type base will bedispersed without a substantial amount of coalescence of the same.

11. A process of producing an emulsion which'comprises dispersing a bitumen-pitch type base in a fluid state in the presence of a mixture` of dispersive media and water vwhile agitating said mixture, and controlling the temperature of the mass during agitation so as to maintain the bitumen-pitch type base in an extensible condition while it 1s being dispersed, producing dispersion of' the base without a substantial coalescence of the saine. p

12. A process of producing an emulsion which comprises dispersing a `bitumen-pitch type base in a fluid state in the presence of a mixture of dispersive media and water while agitating said mixture, and maintaining its temperature at such a point that the bitumenpitch type `basewill be dispersed without asubstantial amount'of coalescence of the same by the introduction of water into the mass at a temperature compensating' for the temperature of the incomin base material.

13. A process of pro ucing an emulsion which comprises dispersing a bitumen-pitch type base liquefied byheat in the presence of a mixture of mineral dispersive media and water while agitating said mixture, aud malntaining its temperature at such Va point persed without a substantial amountoicoalescence of the same. l

14. A vprocess of producing whicli'comprises dispersing a bitumen-pitch .fi/Pe i mixture ofcdispersive media and water while base in a Huid state in the presence of a agitating said mixture, and maintaining its temperature at such a point that the bitumenpitchl typeabaselwill be dispersed without a' substantial :amount of coalescence of.l the' same, said tem erature being materially be- `the bitumen-pitchv base is introduced.. Y v

15. A process l:of I producing an emulsion which comprises .dispersing a bitumen-pitch t base in a fluid state ,in the resence of-a mixture of dispersive media an water while an@ emulsion?" "bitumen-.pitch type base in heated liquid conmaterial in aqueous suspension, and maintaining its tempera-ture at such a point that the b'itumenitch type base will be dispersed without a su stantialamount of eoalescence of the same, said temperature being materially below that at which the bitumen-pitch type. base is introduced.

17. A process of producing an emulsion which comprises adding a bitumen-pitch type base in a fluid state to a mixture of an aqueous medium and a mineral dispersive media taking the form of finely divided powdery material in aqueous suspension while agitating said mixture and maintaining its temperature at Such a point that the bitumen-pitch type base will be dispersed without a substantial amount of coalescence of the same, the proportions of the bitumenpitch type base relative to the dispersive media being in excess of tive to one on the basis of weight. p p

18. A process of producing an emulsion which comprises dispersing a bitumen-pitch type baseA in heatv liquetie y`condition in ail aqueousmedium by subjecting same to agif tation in the presence of mineral dispersive lmedia in aqueous suspension, introducing an aqueous suspensionof mineral dispersive mediaA ata temperature materially below that atv which the bitumen pitch base is introduced,`v Yand controlling the temperature of the mass undergoing ispersion to produce Adispersion` of said base without a substantial amountof coalescence-of the same.

19.511 process lofvproducing an emulsion,

'whicllicomprises dispersing a'heat liqueiiable dition'by subjecting same to agitation in the presence of a dispersive media in aqueous mixture', introducing said-aqueous mixture of-dis ersivev media. at a temperature materially elow that at which the` heat liquefied material is introduced, and controlling the temperature of the mass during agitation so as to maintain the bitumen-pitch type .base in an extensible condition, producing dispersion 'ofthebase- Without a substantial coalescence of( the same. Y

LESTE i;IRsoHBRAUN.

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