US2721144A

US2721144A - Method and apparatus for saturating felt

Info

Publication number: US2721144A
Application number: US291530A
Authority: US
Inventors: Benjamin S Penley
Original assignee: Allied Chemical and Dye Corp
Current assignee: Allied Corp
Priority date: 1952-06-03
Filing date: 1952-06-03
Publication date: 1955-10-18
Anticipated expiration: 1972-10-18

Description

Oct. 18, 1955 B. s. PENLEY METHOD AND APPARATUS FOR SATURATING FELT 4 Sheets-Sheet l Filed June 3, 1952 MMTSIMME ATTORNEY.

Oct. 18, 1955 B. s. PENLEY 2,721,144

METHOD AND APPARATUS FOR SATURATING FELT Filed June 3, 1952 4 Sheets-Sheet 2 INVENTOR.

BENJAMIN S. PENLEY ATTO R N EY.

Oct. 18, 1955 B. s. PENLEY 2,721,144

METHOD AND APPARATUS FOR SATURATING FELT Filed June 5, 1952 4 Sheets-Sheet 3 \NVENTOR.

BENJAM N S. PEN L EY LZM ATTORNEY.

B. s. Pl-:NLEY 2,721,144

METHOD AND APPARATUS FOR SATURATING FELT Oct. 18, 1955 Filed June 5, 1952 4 Sheets-Sheet 4 FIGA.

INVENTOR.

BENJAMIN S. PENLEY ATTORN EY.

United States Patent O 2,721,144 METHOD AND APPAIITEJS FOR SATURATING Benjamin S. Penley, Birmingham, Ala., assignor to Allied Chemical & Dye Corporation, New York, N. Y., a

corporation of New York Application June 3, 1952, Serial No. 291,530 1i) Claims. (Cl. 117-47) This invention relates to saturating felt and more particularly refers to new and improved methods and apparatus for impregnating felt with bituminous saturants such as asphalt, tar and pitch for use as roong, insulation, etc.

Dry felt employed in industry for purpose of saturating with a bitumen is a porous material containing a vast number of small voids and generally having a moisture content within about 3 to 6 percent of moisture. ln conventional commercial practice the felt is saturated by immersion in a liquid body of hot saturant, e. g. hot asphalt at about 475 F. As the hot asphalt penetrates into the sheet of felt it is cooled by the sheet and becomes viscous, so that further penetration is slow or temporarily stopped. The heat of the asphalt converts the moisture in the sheet to steam which together with entrapped air, must escape from the voids of the sheet before the sheet can be completely saturated with the asphalt. When the surface layers on both sides of the sheet are filled with asphalt which has become viscous because of the cooling by the sheet, the escape of the steam and the entrapped air is gradually slowed and does not proceed appreciably until suicient heat ows by conduction into the viscous asphalt to render it uid. Since both asphalt and felt are relatively poor conductors of heat this consumes appreciable time. Accordingly, conventional saturators have attained considerable length in order to provide the necessary time element. ln a modification of the ordinary process only one side of the sheet is brought into contact with the surface of the hot asphalt. The modified process shortens this time a little by permitting the steam and entrapped air to escape through that side of the sheet not in contact with the hot asphalt. However, it still requires the time necessary to reheat the asphalt which has penetrated the surface layers of one side of the sheet and have been cooled thereby.

it is known that the friction of the sheet of felt passing through the body of saturant in a kettle creates a drag which varies as the square of the speed of the sheet and which is proportional to mount of immersion, i. e. length of sheet in the kettle. This hydraulic drag causes tension in the sheet and, when excessive, results in breaks in the felt sheet. This tendency to break is further increased by prolonged immersion which causes or tends to cause charring of the felt or otherwise weaken its structure. Approximately half of the total loss of machine time due to felt failures occurs in the saturator alone.

it has been suggested to preheat felt for the purpose of drying out moisture therefrom by-(a) coating one side of the sheet with hot asphalt, the heat of which asphalt converts the moisture in the sheet to steam which escapes from the unsaturated side of the sheet, and (b) passing the sheet of Afelt through hot rolls which conduct heat to the sheet converting the moisture therein to steam. While both these methods decrease the amount of moisture in the felt they are subject to several inrmities. in method (a) the surface layer of asphalt on one side of the sheet prevents escape of moisture and air during complete saturation of the sheet until the surface layer becomes suiiiciently heated to be in a liuid condition thereby prolonging the time for saturation. In method (b), due to the insulating properties of the felt, incomplete moisture and air removal is effected unless extremely 2,721,144 Patented Oct. 18, 1955 ice high temperatures and prolonged time are employed which may result in charring and deterioration of the felt.

Because of the inherent limitations of the commercial processes for saturating felt due to entrapped air and moisture and long immersion time required, it has been found impractical to employ saturants of high softening point, above about F. As a. result, shingles of desired rigidity are not produced and, furthermore, the shingles produced in the conventional manner require additional processing steps to prevent them from bleedingj sliding or blistering Sliding is that defect in rooting which is evidenced by a gross slippage of the face coating from the saturated felt. Blistering is that defect evidenced by an eruption of various-sized vesicles within the coating or between the coating and the saturated felt.

One object of the present invention is to provide methods and apparatus for saturating felts at rates to reduce the time of immersion to a value appreciably lower than hitherto obtained.

Another object of the present invention is to provide methods and apparatus minimizing hydraulic drag during saturation of felt thereby substantially eliminating breaks during such saturation.

A further object of the present invention is to provide methods and apparatus for reducing the time of immersion of the felt in the saturant so that charring of felt will not occur.

A still further object of the present invention is to provide apparatus for saturating felt which substantially completely encloses the saturant thereby reducing lire hazards to a Another object of the present invention is to provide improved methods and apparatus for the elimination of entrapped gases and water vapor from felt.

Another object of the present invention is to provide methods and apparatus for the saturation of felt with high softening point saturants thereby providing desired rigidity of shingle stock by the saturation step.

Further objects and advantages will be apparent from the following description and accompanying drawings.

Referring to the drawings:

Figure l is a diagrammatic ow sheet illustrating the process of the present invention.

Figure 2 is an isometric View in partial section of the pressure saturator.

Figure 3 is a front elevation in partial section of the pressure saturator.

Figure 4 is a plan View of the grooved cylinder roll employed in the pressure saturator.

Figure 5 is an enlarged section of the grooved cylinder roll taken on line 5 5 of Figure 4.

Figure 6 is an enlargement in section of a portion of the pressure saturator to show in detail the construction of the saturator at the point of inlet of saturant and the position of the doctor blade.

Figure 7 is an isometric view in section of a portion of a shingle to illustrate its structure and composition.

Referring to Figure l, cold, moist felt 1 termed in industry as dry felt is continuously drawn through a preheater designated generally by numeral 2 wherein the felt is preheated and moisture expelled therefrom. Preheater 2 is generally constructed of an outer shell 3, an inner grooved perforated rotating drum 4 and entrance and

exit pressure rolls

5 and 6. Sheet felt 1 passes between pressure roll 5 and drum 4 driven by any suitable power means, as for example an electric motor not shown in the drawing, and then emerges from preheater 2 by passing between exit pressure roll 6 and drum 4. A hot gaseous fluid such as combustion gas, air or superheated steam, preferably at a temperature below 500 F. to avoid charring of the felt and under superatmospheric pressure, about 3-10 p. s. i. gauge, or higher, is introduced through line 7 into shell 3 maintained under superatmospheric pressure by means of suitable seals, not shown in the drawing. Hot combustion gas for preheating the felt may be generated by forcing air and fuel through

respective lines

8 and 9 into furnace 11 wherein combustion takes place and the hot combustion gases then discharged through conduit 7. Control of the temperature of the combustion gases may be accomplished by one or a combination of conventional methods such as passing the combustion gases from furnace 11 in indirect heat exchange with a cooling medium, direct injection of cold air into the hot combustion gases to temper them, or introducing excess air into furnace 11.

The hot gases introduced through line 7 into preheater 2 in the space between drum 4 and shell 3 can escape only by passing through the felt sheet 1 as it lies against drum 4 and then through perforations in drum 4 into the interior of drum 4. The gases partially cooled by passage through the felt sheet then escape from the interior of the drum through hub emaust conduit 12. A small portion of drum 4

intermediate pressure rolls

5 and 6 is not covered by the sheet of felt permitting a minor amount of the gases to pass through the perforations in the drum at that point. Therefore, a covering 13 in the nature of a hood is disposed above preheater 2 to collect the escaping gases and release them to the atmosphere through stack 14. The pressure of the hot gases entering preheater 2 holds sheet 1 tight against drum 4 and rotation of this drum provides the necessary pull to carry the sheet through the preheater without imposing undue stress on the sheet. The hot gases desirably enter the preheater at temperatures up to the maximum permissible without charring the felt.Y In the case of felt made from wood, paper and rag fibers, this temperature is about 500 F. but depends somewhat on the speed at which the felt is passed through the preheater. Passage of the hot gases through the felt brings the source of heat into minutely intimate contact with the individual fibers of the felt; the felt is heated rapidly, the moisture in the felt is converted to steam and the steam and entrapped air are driven out of the felt so that the felt emerges from the preheater substantially bone dry and at a temperature of 20 to 100 F. to below that of the entering top gases. This temperature can of course be varied by changespin velocity of the felt, quantity of hot gas per unit of felt, and size of the preheater. The felt leaving preheater 2 is at a state of dryness and temperature ideal for saturating with asphalt. Y

The construction and method of operation of the pre? heater is described in greater detail in my cofiled application, Serial No. 291,529, tiled June`3, 1952, entitled Felt Heater and Dryer.

The dry hot felt 1 pulled by rolls 15 and guided by roll 16 next passes throughV loop 17 which is enclosed, not shown in the drawing, to avoid loss of heat. Loop 17 can be small in size--it need only be adequate to permit guiding and to provide sufficient slack in the sheet of felt so as to prevent tension and breakage of the felt during its passage from the heater to the pressure saturator.

The pressure saturator designated Y generally by numeral 18 is constructed of a grooved imperforate cylinder roll 19 surrounded by shell 21, entrance pressure roll 22, exit pressure roll 23, and sealing means more clearly shown in Figure 2 as will be described later. The dry hot felt sheet passes between entrance pressure roll 22 and grooved roll 19 driven by any suitable power means, around grooved drum 19, and the saturated felt emerges from saturator 18 after passing between exit pressure roll 23 and grooved drum 19. Hot saturant at conventional temperatures, e. g. up to about 475 F., is introduced through

lines

24, 25 and valve 26 into the space between shell 21 and grooved drum 19. Within the pressure saturator felt sheet 1 is carried by roll 19 because the pressure of the hot saturant holds the sheet tight against grooved roll 19. Therefore, pull on the sheet is much less than in conventional type saturators. The hot saturant under superatmospheric pressure introduced into the space between shell 21 and roll 19 can escape only by passing through the hot felt sheet 1 as it lies against roll 19 and thence along the circumferential grooves around the drum until the hot saturant emerges at the top between pressure rolls 22 and 23 where roll 19 is not covered by the felt sheet. Saturant accumulates at this point until it overflows weir 27 and returns through pipe 28 to surge tank 29. Excess saturant is recirculated from the bottom of surge tank 29 through line 31 and forced by pump 32 through

lines

33 and 44 into saturant storage tank 35. Pump 36 maintains suitable pressure on the hot saturant to force it through the felt sheet; this pressure is of the order of l-lO p. s. i. gauge and varies according to thickness of the sheet, viscosity of the saturant as dictated by its softening point and temperature, speed of the sheet and size of the equipment. The immersion time to which the felt sheet is exposed to hot saturant in the pressure saturator is of the order of l to 5 seconds; typical time is 11/2 seconds. Immersion time in a conventional type saturator ranges from 45 to 70 seconds. Since both the felt sheet and the saturant are hot there is no appreciable cooling of the asphalt and no viscous layer is formed with the attendant time required to reheat. The hot saturant enters and passes through the felt sheet in one direction driving ahead of it hot gases entrapped in the sheet. Since all impediments to saturation have been removed or avoided, saturation proceeds uniformly, completely and very rapidly.

In order to replenish the Yhot saturant consumed in saturator 18 and maintain the temperature of the saturant therein, saturant from storage tank is withdrawn through line 34 from saturant storage tank 35, forced by saturant pump 36 through line 37 and heat exchanger 38 wherein the saturant is heated to desired operating temperatures under automatic control, by indirect contact with a heating fluid, as for example hot oil, passing through coil 39, thence through

lines

41, 24, 25 and valve 26 into saturator 18. The saturant may be returned from surge tank 29 to saturant storage tank 35 via

lines

31, 33, 44 and valve 45. Valve 42, which may be operated manually or automatically, bleeds oi a portion of the saturant owing through line 24, directing it through line 43 into surge tank 29, thereby controlling pressure in saturator 18. Valve 46 in line 24 may be partially opened to by-pass a portion of the saturant flowing through line 33. The foregoing saturant circulatory system provides a method of controlling the volume, temperature and pressure of a continuous stream of hot saturant passing in contact with the felt.

In the process of the invention, the impregnating asphalt moves rst through the felt sheet from outer side of the supported sheet immersed in a body of asphalt toward the support, for example, rotating drum 19 kof the preferred pressure saturator of the drawings. The hot asphalt emerged from the inner section of the sheet passes as a multiplicity of separate streams through the passageways or conduits dened by the inner unsupported portions of the sheet and by the channels occurring between adjacent areas or surfaces engaging the sheet, for example, lands 112 (Figure 6), until disengaged from the sheet when the latter is removed from its support. Hence, in the process of the invention, the ow of hot asphalt described serves a threefold purpose. First it holds the sheet against its support, preventing undue stresses therein. Then it moves generally from the inner to the outer surfaces of the sheet, heating it and driving out air and moisture. Thereafter, the hot asphalt remains in contact with the inner surface to provide such additional heat and penetrating eiect as may be needed to complete the saturation in very short or even minimum time, permitting preservation to maximum extent of the desired structural characteristics of the felt. Duration of contact of the streams of asphaltwith the inner sheet surface is a function of porosity of the felt sheet and the vis- CQsity of the asphalt during and after passage therethrough, as well as of the total immersion time of the sheet in the body of asphalt.

Threading, which is an important phase of the operation, is accomplished by passing sheet 1 over guide 16, then over roll 22 employing guide 87 (Fig. 3) to guide sheet 1 thereon, and then passing the sheet into the nip of roll 22 and drum 19, the initial stage of threading carried out in the absence of pressure. After sheet 1 has entered the nip, the pressure is turned on which holds sheet 1 against drum 19 while the machine is started and until the sheet reaches exit roll 23. To insure high velocity ow of saturant through the annulus formed by drum 19, and shell 40, the cross-sectional area of the annulus is desirably made small to provide a minimum clearance between sheet 1 and shell 49 thereby aiding in maintaining more uniform pressure conditions during threading and saturation. Doctor blade 92 serves to guide sheet 1 onto drum 19 during threading and prevent the sheet from continuing around roll 22. Exit sheet guide 99 serves to guide the sheet when threading into the nip of

rolls

47 and 23.

Figure 2 is an isometric drawing of pressure saturator 18 showing its construction in more detail. The felt sheet 1 or felt fabric or web, as it is sometimes referred to, enters pressure saturator 18 by passing between entrance pressure roll 22 and grooved cylinder roll 19, around grooved cylinder roll 19 emerging by passing between exit pressure roll 23 and cylinder 19, and then between squeeze roll or ringer roll 47 and exit pressure roll 23. The entire shell designated in Fig. 1 by numeral 21 surrounding cylinder 19 is constructed of two sections, an upper half 48 open at its top and a lower half 49. Hot saturant is introduced into pressure saturator 1S through conduit 25. The body of saturant in the pressure saturator is maintained under pressure by means of seals pressing against the sides and ends of pressure rolls 22 and 23. The seal construction at the side of exit pressure roll 23 comprises a seal supporting block 51 on which is disposed seals 52 which in turn are held in place and urged against pressure roll 23 by means of springs on pusher bar 50, dogs 53 and vertical and horizontal seal pressure springs 54. Corner seal 55 is retained in position by spring 56. The end of pressure roll 23 is sealed by seal 57 which is retained in position pressing against roll 23 by means of pusher bar 58 and springs 59. A similar sealing spring structure is provided on the opposite end of pressure roll 23. Likewise, the seals on entrance pressure roll 22 are similar in construction to those described in connection with exit pressure roll 23. As will be seen from the drawing, pressure roll 22 is provided with an entrance seal supporting block 61 on which is mounted pusher bar 62, dogs 63 and vertical and horizontal springs 64. Also shown is corner seal 65 with corresponding pusher bar 66 and spring 67, as well as end seal 68, pusher bar 69, dogs 71 and springs 72. As seen in the drawing a portion of grooved cylinder roll 19 extends above shell 48. To prevent leakage at this point seal 73, pusher bar 74, dogs 75 and springs 76 are provided.

Thus, saturant under pressure entering through conduit must pass through felt sheet 1, thence along the grooves in grooved cylinder 19 and escape from the top of grooved cylinder 19 at points intermediate pressure rolls 22 and 23. A saturant overilow pan 77 enclosed by

walls

78, 79, 81 and 82 collects the saturant after it has traversed the grooves in drum 19. Any slight leakage of saturant through the seals surrounding pressure rolls 22, 23 and cylinder 19 also collects in pan 77. Pan 77 is divided into two sections by means of a Weir composed of stationary Weir bar 83 an-d movable Weir gate 84 whichv latter permtis adjustment of the height of the Weir. Two drain or dump gates 85 are incorporated in the weir to by-pass the weir, if desired, particularly when draining the system of saturant. In operation the level of saturant is permitted to build up to'a height above the uppermost portion of grooved cylinder 19 thereby acting in the nature of a hydraulic seal. EX- cess saturant overflows Weir gate 84 and then drains through saturant drain pipes 28 to surge tank 29 shown in Figure 1. Cylinder 19 is rotated by power means not shown in the drawing connected to shaft 86 provided with a suitable stuiiing box and extending from

shell

48, 49.

Referring to Figure 3 sheet 1 passes over guide 16, thence guided by entrance guide sheet 87 onto pressure roll 22 and between pressure roll 22 and grooved cylinder roll 19. Deckle plate 88 held in position by support 89 extends to the edge of sheet 1. In the upper part of shell 4S is provided a small chamber 91 for the introduction of saturant through conduit 25 and to provide space for the installation of doctor blade 92 supported by spring mountings 93 to urge the doctor blade against entrance pressure roll 22. Figure 3 also shows a section of the seals pressing against roll 22 which seal arrangement rests on iloor 94 of overllow pan 77 which floor is also the ceiling for chamber 91. The entrance seal constitutes seal supporting block 61, entrance roll seal 65, dogs 63, pusher bar 62 and pressure springs 64. As grooved cylinder 19 is rotated by power means driving shaft 86, web 1 clings to cylinder 19 and exits by passing between exit pressure roll 23, thence between squeeze roll 47 and exit pressure roll 23 and nally along wiper rolls 104 resting on wiper roll support 96. Extension of shaft 86 carries a large gear not shown in the drawing, which is driven by a pinion, not shown, the latter being powered by conventional means such as an electric motor or a pulley. The above large gear meshes with pinions, not shown, on the extended shafts of

rolls

22 and 23 which actuates these rolls. On the extended shaft of roll 23 there is also a sprocket, not shown, which through chain 128 drives sprocket 127 that is mounted on the extended shaft on wiper roll 125. Also on the extended shaft of roll is gear 126 meshing with another gear of the same number that is mounted on the extended shaft of roll 104 to drive this roll. Exit deckle 97, support 98 for the exit deckle, and exit sheet guide 99 similar to entrance deckle 88, support 89 and entrance guide sheet 87 are disposed adjacent exit pressure roll 23. Deckles 88 and 97 are used to blank oit" rolls 22 and 23 beyond the edge of sheet 1. These deckles may be substituted for other deckles of different width to permit operation with sheets of varying Widths. The structural support for inlet pressure roll 22 is indicated by numeral 101; and the exit pressure roll 23 and squeeze roll 47 structural support is shown generally by numeral 102.

Saturant overilow pan 77 is divided by weir 27 composed of stationary weir bar 83 and movable weir gate 84. Plate 103 extending at an angle from overflow pan 77 and beneath wiper rolls 104 collects excess saturant removed by the wiper rolls which saturant drains down plate 103 into overflow pan 77. Overflow saturant ows down through drainpipes 28 into surge tank 29. Shell 49 may be provided with clean-out plates 105 to permit access to the interior of shell 49 primarily for the purpose of cleaning it at the end of the run. Also at the end of the run all saturant may be removed from the interior of shell 49 through drainpipe 106. Pressure is maintained on entrance pressure roll 22 and exit pressure roll 23 by means of spring loaded rods designated generally by numeral 107. Vertical adjustment of pressure on pressure rolls 22 and 23 for the purpose of adjusting the space for paper thickness between pressure rolls 22 and 23 and grooved cylinder roll 19 is accomplished by manipulating wheel 108 connected by conventional gears to rods 107. The usual structural elements designated by numeral 109 support the entire saturator structure.

Figure 4 is a plan view of grooved cylinder roll 19 showing shafts 86 extending therefrom. As will be noted a plurality of adjacent parallel flow grooves 111 extend around cylinder 19.

One important advantage in employing an imperforate 7 grooved drum as illustrated in Figures 4 and 5 is that varying widths of web may be accommodated in the apparatus without change in structure or operation except for the slight mechanical change required in changing the deckles. `Of importance, when saturating a sheet supported by a drum having circumferential grooves is the fact that the entire sheet including particularly the edges is fully saturated by Saturant under pressure. The grooved drum 19 as illustrated in Figures 4 and 5 also has the advantage of having a minimum land area, i. e., surface which is in physical contact with the felt resting on the grooved drum 19. This land area is designated by numeral 112 (Figure 5) and as previously mentioned has a width of about V32, Whereas the open area represented by numeral 111 has a width of about fief-thus the land area represents about 25% of the total area. It is important to have the land area as small as possible in that it permits greater exposure of the'felt to Saturant passing therethrough and, consequently, more rapid and uniform saturation of the felt. Furthermore, it will be noted that the land area of the grooved drums are in the form of very narrow (1/32) strips with Saturant flowing through on each side of the strips which Saturant, as found in practice, readily permeates the felt resting on the strips of land area. In contrast, were a perforated drum employed the holes in the drum could not in practical operation-be greater than 1A diameter or else the felt would push Vthrough the perforations with distortion and disruption of the felt. In a perforated drum having 1A holes the land area is approximately 2/3 of the total area, and this land area also has numerous points between the holes of relatively large size in contact with the drum through which it is diflicult to pass Saturant through the felt with the result that longer time is required and less uniform saturation of the felt is accomplished.

Figure is an enlargement of a portion of Figure 4 to show more clearly the nature of flow grooves 111. Desirably, the flow grooves 111 are constructed to have an opening of about 2%,2", a depth of about 1A" and a land area, as indicated by numeral 112, of 1/32. The overall dimensions of grooved cylinder 19 may be about 3 feet in diameter and about 4 feet or more long.

Figure 6 is an enlargement of a portion of the saturator showing in more detail the position of the doctor blade and the chamber into which Saturant is introduced. Hot Saturant is pumped under pressure through inlet 25 into chamber 91 flowing through web 1 carried on grooved cylinder roll 19. Above cylinder 19 is entrance pressure roll 22 against which doctor blade 92 presses. To the left of entrance pressure roll 22 is shown entrance seal supporting block 61 resting on the ceiling 94 of chamber 91 which also acts as a floor for overiiow pan 77. As seen in Figure 6 doctor blade 92 is mounted and adjusted by means of bolts 93, one of which is provided with a spring 113 to urge doctor blade 92 against pressure roll 22.

Ordinarily, threading the pressure saturator is a difcult task. In the present construction, as illustrated by Figures 3 and 6, threading the pressure saturator is quite simple. This is accomplished at the start of the operation by first placing the end of Web 1 along pressure roll 22 until the end of felt 1 extends a short distance beyond the bite between cylinder 19 and pressure roll 22. Saturant under pressure is then introduced through inlet 25. Cylinder 19 is rotated slightly counter-clock wise. The Saturant under pressure in chamber 91 pushes against the outer surface of felt 1 causing it to cling to cylinder 19. Doctor blade 92 and curved wall 114, which is an extension of upper shell 48, guide the felt 1 along cylinder 19 and prevent it from straying off cylinder 19. Since the hot Saturant under pressure fills the annulus between cylinder 19 and

shell

48, 49, the pressure of the Saturant causes the felt to cling to cylinder 19 during the entire travel of felt 1 along cylinder 19 with theY result "8 that during the threading of felt 1 and subsequent travel of felt 1 along cylinder 19, the passage of web 1 along cylinder 19 continues without any diliiculty.

In conventional saturators dry felt of 52 gauge can not be saturated satisfactorily with asphalt at felt speeds much in excess of 250-300 lineal feet per minute. In the practice of the present invention employing the preheater and pressure saturator described above, felt speeds of 360-400 lineal feet per minute were attained with satisfactory results. The open surface area of asphalt in conventional saturators has a length of 20 feet or more. This open surface of hot asphalt is a source of fire hazard. The length ofasphalt surface in the pressure saturator of the present invention is only 3 to 4 feet.

In the conventional method of producing shingles, felt of about 50-52 gauge (51 gauge is equal to felt of 0.056) is pulled through a vat of melted asphalt. From long experience it has been found impractical to employ asphalt having a softening point higher than 13S-140 F. as the Saturant because if higher melting point asphalts were employed .the time required for saturating felt would be too long and the hydraulic drag would be too great. The resultant felt saturated with the 13S-140 F. softening point asphalt is quite flexible and its surface sticky. One side of the saturated asphalt, and for con, venience this side will be termed bottom side, is coated with a thin layer of a high softening point asphalt of the order of 20D-240 F. softening point. This coating termed seal coat is covered with talc or mica to pre-Y vent sticking. The opposite side of the felt, i. e., the upper surface of the saturated felt, is covered with a relatively heavy layer of asphalt of about 20G-240 F. softening point. This upper layer, top coating, of high softening point asphalt is then covered with a layer of granules or crushed'slate and is the surface exposed to the weather when used as shingles. The use of high softening point asphalts, i. e. in excess of 200 F. softening point, is undesirable in that such asphalts upon exposure to the atmosphere oxidize and become brittle. Nevertheless, the industry had found it impractical to employ lower melting point asphalts as top coating because at the point of contact between the top surface of the felt saturated with 13S-140 F. softening point asphalt and the bottom surface of the top coatingV there is a tendency for the top coating to detach itself from the top surface of the saturated asphalt unless the top coating has a softening point in excess of 200 F. Furthermore, and perhaps more important, the finished shingles containing a Saturant of 13S-140 F. softening point asphalt lack sufficient rigidity, and in strong winds tend to blow up or ap on a Vroof or similar structure which they cover, which action causes leaks.

In practice of my invention I have found that conventional felt employed for the production of shingles can be saturated with 175-185 F. softening point asphalt to produce a shingle having improved rigidity. Furthermore, I have found it unnecessary to employ a top coating asphalt having a melting point in excess of 200 F. and instead may employ a top coating of asphalt having a softening point below 200 F., preferably 175185 F. thereby increasing the life of the shingle when exposed to the atmosphere. When the top coating and the asphalt employed for use as Saturant have substantially the same softening point (ll85 F.) a firm bond is formed between the top coating and the saturated felt and the diculty of the top layer detaching itself from the saturated felt is obviated.

Further, the use of -185 F. softening point asphalt for saturating the felt permits the elimination ofa seal coat required when lower melting point asphalts are employed for saturating felt in the production of shingles. All that is necessary when employing the 175-185 F. softening point asphalt for saturating felt is simply coating the lower surface with talc or mica to prevent .stick- 9 ing. Thus, the practice of my invention permits the production of improved shingles having longer life and greater rigidity at lower cost.

Figure 7 is a cross section of a shingle illustrating its composition and structure. The inner layer 116 of the shingle is composed of felt of about 0.056" thickness saturated with asphalt having a softening point of 175-185" F. Top coating 117 is about 0.060 thickness and consists of asphalt having a softening point of about 175-190 F. The surface of top coating 117 is covered with a layer of granules 118. Beneath the saturated felt 116 is a thin layer of seal coat 119 of about .003- .005" thickness consisting of asphalt having a softening point of 175-190 F. The seal coat is covered with a layer 121 of talc or mica or other material to prevent sticking. lf desired, seal coat 119 may be omitted and the bottom surface of the saturated felt 116 directly covered with talc or mica 121. Shingles produced vvith 175-185 F. softening point asphalt in accordance with the present invention have greater rigidity and do not deteriorate as rapidly as conventional shingles formed by saturating felt with 13S-140 F. softening point asphalt.

When saturating felt with high melting point asphalt, e. g., l70185 F. softening point asphalt, it is highly desirable to iirst treat the felt in preheater 2, Figure 1, to facilitate the saturation of the felt. The use of the preheater while benecial is not necessary when impregnating felts with low melting point saturants.

Although certain preferred embodiments of the invention have been disclosed for purpose of illustration it will be evident that various changes and modifications may be made therein without departing from the scope and spirit of the invention.

I claim:

1. A continuous method for saturating felt which comprises continuously passing hot gas under pressure against one surface and through a continuously moving sheet of felt thereby heating and expelling entrapped moisture from the felt, continuously passing the thus heated dry felt around an imperforate circumferentially grooved rotating cylinder, continuously passing hot liquid bituminous saturant under superatmospheric pressure against the outer surface of the felt sheet lying against the grooved cylinder and through the felt and into the grooves of the cylinder thereby expelling entrapped gases from the felt and replacing it with saturant, continuously releasing excess saturant passing through the felt via the channels formed by the grooves into an overflow pan having walls surrounding the top of the imperforate grooved cylinder to receive and collect the released saturant, and continuously withdrawing the saturated felt sheet from the imperforate grooved cylinder.

2. A process for saturating felt which comprises passing a felt sheet through an annulus formed by an inner imperforate circumferentially grooved rotating cylinder` and an. outer shell surrounding all but the top of the imperforate grooved cylinder with seals provided to maintain pressure on said annulus, introducing hot liquid bituminous saturant under pressure through the outer shell into the annulus against the outer surface of the felt sheet around the grooved cylinder thereby expelling entrapped gases from the felt and forcing the saturant through the felt sheet into the grooves lying on the inner surface of the felt sheet, and releasing excess saturant passing through the felt sheet into the grooves at the top of the imperforate grooved cylinder into an overow pan having walls surrounding the top of the imperforate grooved cylinder to receive and collect the released saturant.

3. Apparatus for saturating felt comprising in combination, an imperforate circumferentially grooved rotating cylinder, a shell surrounding all but the topmost portion of the grooved imperforate cylinder, an inlet and an exit pressure roll disposed above on each side of the grooved cylinder immediately adjacent thereto, each said pressure roll being spaced from the grooved cylinder by about the thickness of the felt to permit the passage ci' felt between each pressure roll and the grooved cylinder, seals surrounding the outer sides and ends of the pressure rolls and the up -er exposed ends of the grooved cylinder adapted to maintain pressure on the liquid bituminous saturant introduced into the space between the grooved imperforate cylinder and the surrounding shell, and an overow pan having walls surrounding the pressure rolls and seals at the top of the outer shell adapted to receive and collect excess liquid bituminous saturant escaping from the grooves or" the grooved cylinder at a point between the two pressure rolls.

4. Apparatus as claimed in claim 3 including a doctor blade adjacent the inlet pressure roll adapted to guide felt sheet from the inlet pressure roll onto the imperforate grooved cylinder.

5. Apparatus as claimed in claim 3 wherein said shell surrounding said imperforate grooved cylinder is disposed to form an annulus of small cross-sectional area to insure high velocity ow of saturant through the annulus.

6. Apparatus as claimed in claim 3 including an entrance sheet guide adjacent the inlet pressure roll adapted to guide felt sheet into the nip of the inlet pressure roll and the imperforate grooved cylinder, a squeeze roll adjacent the exit pressure roll, and an exit sheet guide adjacent the exit pressure roll adapted to guide felt sheet into the nip of the exit pressure roll and the squeeze roll.

7. Apparatus as claimed in claim 3 including a conduit for draining saturant from the overflow pan, a tank into which saturant from the conduit ows and means for returning saturant from the tank to the space between the imperforate grooved drum and outer shell.

8. Apparatus as claimed in claim 3 including a weir partitioning the overow pan and adapted to control the height of saturant liquid in the overiow pan covering the exposed upper portion of the grooved cylinder.

9. Apparatus as claimed in claim 3 wherein the grooves in the imperforate cylinder have openings of about 329,2 width and the ridges of the grooves have a width of about 1/32".

10. In saturating felt sheet with bituminous saturant, the process comprising applying one side of the sheet to a support providing a multiplicity of raised spaced-apart surfaces having channels therebetween, forcing liquid bituminous saturant under superatmospheric pressure through said sheet from the unsupported side thereof to press said sheet against said surfaces and to bridge said channels, and conducting excess liquid bituminous saturant emerged from the supported side of said sheet as a multiplicity of streams along and in direct contact with said last named side through the conduits deiined by said sheet and channels.

References Cited in the le of this patent UNITED STATES PATENTS 263,668 Stelwagon Aug. 28, 1882 925,263 Ayrault June 15, 1909 1,109,819 Buhl Sept. 8, 1914 1,268,430 Cady iune 4, 1918 1,275,216 Cady Aug. 13, 1918 1,714,206 Black et' al May 21, 1929 1,736,633 Schutte Nov. 19, 1929 1,831,630 Manker Nov. 10, 1931 1,842,111 Pater Jan. 19, 1932 1,845,775 Zavertnik et al Feb. 16, 1932 1,942,383 Dickhaut et al Ian. 2, 1934 2,040,514 Dillon May 12, 1936 2,040,529 Pearl May 12, 1936 2,083,731 Miller June 15, 1937 2,117,355 Pearl May 17, 1938 2,176,835 Cumfer Oct. 17, 1939 2,206,915 Ochs July 9, 1940 2,326,723 Fasold et al Aug. 10, 1943 2,400,681 Bristol May 21, 1946

Claims

1. A CONTINUOUS METHOD FOR SATURATING FELT WHICH COMPRISES CONTINUOUSLY PASSING HOT GAS UNDER PRESSURE AGAINST ONE SURFACE AND THROUGH A CONTINUOUSLY MOVING SHEET OF FELT THEREBY HEATING AND EXPELLING ENTRAPPED MOSITURE FROM THE FELT, CONTINUOUSLY PASSING THE THUS HEATED DRY FELT AROUND AN IMPERFORATE CIRCUMFERENTIALLY GROOVED ROTATING CYLINDER, CONTINUOUSLY PASSING HOT LIQUID BITUMINOUS SATURANT UNDER SUPERATMOSPHERIC PRESSURE AGAINST THE OUTER SURFACE OF THE FELT SHEET LYING AGAINST THE GROOVED CYLINDER AND THROUGH THE FELT AND INTO THE GROOVES OF THE CYLINDER THEREBY EXPELLING ENTRAPPED GASES FROM THE FELT AND REPLACING IT WITH SATURANT, CONTINUOUSLY RELEASING EXCESS SATURANT PASSING THROUGH THE FELT VIA THE CHANNELS FORMED BY THE GROOVES INTO AN OVERFLOW PAN HAVING WALLS SURROUNDING THE TOP OF THE IMPERFORATE GROOVED CYLINDER TO RECEIVE AND COLLECT THE RELEASED SATURANT, AND CONTINUOUSLY WITHDRAWING THE SATURATED FELT SHEET FROM THE IMPERFORATE GROOVED CYLINDER.