US2590850A - Method of treating sheet material coated with gelatine - Google Patents

Description

Aplll l, 1952 1 DUNGLER l 2,590,850

METHOD OF' TREATING SHEET MATERIAL COATED WITH GELATINE Filed Jan. 14, 1950 l IN VEN TOR.

JULIEN DUNGL ER.

Patented Apr. l, 1952 METHOD OF TREATING SHEET MATER-IAL -GOAT-ED WITH GELATINE Julien Dungler, Basel, Switzerland Application January 14, 1950, Serial No. 138,685 In France October 10, 1949 The present invention -relates generally to a process of treating textile and other` cellulosic materials, especially for the removal of liquid therefrom.

Processes of the general character `referred to may serve a variety of purposes, such as, for example, the drying of high-quality paper after sizing or impregnation with gelatine, the evaporization of inflammable constituents of substances used for impregnating fabrics, the polymerization of impregnating agent or agents in the manufacture of paper products to render same washable or water resistant, the evaporization of a liquid serving as a vehicle for the agent in a suspension, solution, emulsion and the like to be fixed to and within the fibres of the treated textile or similar product.

In all the aforesaid and like processes, it is important that the desired effect be obtained as rapidly as possible for the following reasons:

From an economic point of View it will be apparent that a shorter duration of the treatment will allowprocessing of a greater number of units or a greater length of material (Where the latter is fed to the installation continuously and in bulk) in a given period of time.

Any prolongation of the treatment under heat A beyond the necessary minimum may detrimentally affect the finished product, causing, for

instance, the impregnating agent to travel to the 5 to be applied to the material within a given unit f of time is determined by the desired rate of heat treatment, i. e. by the quantity of liquid to be evaporized during such unit of time. tofore customary, a gaseous fluid is used as the carrier or vehicle of sensible heat which by its contact with the product under treatment progressively raises the temperature of the latter, the amount of heat (calories) made available will depend upon the specific heat of the duid employed, upon its quantity and upon its temperature. Inasmuch as the specific heat of the gases adapted to be used for this purpose is relatively W, and since their quantity and operating temperature is limited by practical considerations, such as available space and the need for avoiding harmful thermal effects, respectively, the minimum duration of a treatment according to conventional methods is necessarily quite long.

Y One of the objects of the present invention 1 Cla-im. (Cl. .S4-23) If, as hereis to provide a method of and means for treating a fabric and like cellulosic article from- Which moisture is to be removed, in such manner as to satisfy the above-stated requirements for high-speed operation.

Another object of the invention is to provide a method of and means for thermally treating impregnated fabric and like material from which volatile substances of inflammable character are to be removed, in such manner that all danger of fire or explosion is averted.

A further object of this invention is to provide a method of and means for applying heat to fan article of the aforesaid character with suicient heat impact that the heating effect will substantially instantaneously penetrate deep into the interior or core of the libres of the aforesaid article under treatment, thereby evaporizing the liquid present therein without necessitating a gradual or preliminary rise to the surface of said article.

Still another object of the invention isto provide a method of utilizing applied vand/or the latent heat (e. g. heat of condensation or of chemicalreaction) of a suitable carrier medium for purposes of the treatment desired.

Yet a further object of the invention is to Drovide a method which utilizes as a carrier medium a fluid available in great abundance and at low cost.

A still further object of the invention is to provide a method of removing liquid substance from the surface and the interior of an impregnated article, by the application of a heat carrying fluid, in such manner that the vapors of the liquid thus removed may themselves serve as part of the heat carrying fluid.

According to a further feature of the present invention, the above and other objects are attained by using as heat carrying medium superheated steam o1' vapor or a mixture of a suitable fluid containing superheated steam, the conditions of heat treatment being chosen or influenced so as to bring about at least partial condensation of the steam or of the aforesaid mixture on and within the fibrous material under treatment.

According to another feature of the invention, the heat carrying fluid is subjected to impin'gevment upon the surface of the aforesaid material 'the interior as Well as onto the surfacegcf the material while the latter, for example in the form of lengthy piece material, passes continuously through a substantially closed chamber or defined space.

The invention further contemplates the aforesaid treatment of the material with the exclusion or absence of air, the air being expelled from said chamber by admitting superheated steam into the latter and creating an atmosphere of superheated steam therein at the beginning of the process and operation.

According to the invention superheated vapor may be formed at least in part by moisture expelled from the material (inherent therein or previously added) treated, or by the moisture content of a treatment iluid which is being or was previously applied to the material while the latter is in the heating chamber.

Furthermore, superheated steam or a fluid mixture containing the latter may be admitted to the chamber from therewithout, or superheated vapor -or steam may be generated, at least in part,

within the substantially air-free chamber.

It is preferred to provide for a continuous exhaust of vapors accumulating within the treatment chamber, so as to maintain the pressure inside the chamber at a predetermined value, the exhausted vapor mixture being subjected, if desired, to fractional distillation for recovery of its constituents.

According to another aspect of the invention, an apparatus for treating fabric and like material in bulk and by a continuous process in the manner set forth above, comprises, in combination, essentially a thermally insulated and substantially closed treatment chamber, conveyor means for continuously advancing the material through said chamber, blower means inside the chamber for directing concentrated and individual jets of superheated fluid, representing a carrier of sensible or effective and/or latent heat, for impingement upon the surface or surfaces of the material to be treated, discharge means allowing for at least partial evacuation of fluid excess from the chamber, and means for impinging a treatment fluid on the material treated.

The above and other features and objects will become apparent from the following description of a preferred embodiment of the invention. In the drawing:

Fig. l indicates in section and somewhat schematically an apparatus for the treatment of elongated web or other fibrous, preferably sheetI material in a continuous operation.

Fig. 2 is a'fragmentary sectional view of a detail of the apparatus referred to in the specification.

Asshown in the drawing, a thermally insulated chamber I contains an upper blower box 2 and a lower blower box 3 which are equipped with sets of blower nozzles 4 and 5, respectively, these nozzles being separated from one another by respective exhaust channels 4a. and 5a. Fluid is supplied to the discharge orv blower nozzles by fans 6 and "I, respectively, whose respective intake ports 8 andS open into treatment chamber I. Heaters, schematically indicated at It and II, are disposed inside the blower boxes 2 and 3.

' The chamber I is furthermore provided with blower nozzles l2 and I3 to which a gaseous treatment fluid is supplied by way of a duct or pipe I4 having a shut-off valve I5. These latter nozzles are preferably disposed intermediate the blowers or fans 6 and I, respectively, on the one hand, and the heating elements I0 and II,

on the other hand; it will be understood, however, that they may also be mounted at some other suitable location within the heating chamber I.

Additional nozzles IGS-Il, receiving a treatment liquid by way of a conduit I8 provided with a shut-off valve I9, may be disposed in certain of the exhaust channels 4a between the aforesaid nozzles 4. It will be understood that additional nozzles may be similarly provided at exhaust channels 5a formed between the nozzles 5.

An exhaust conduit 20 opens into the chamber I in order to allow for the at least partial evacuation of the treatment fluid.

This exhaust conduit 20 may be connected to any suitable apparatus (not Shown) for utilizing the evacuated iluid, such as a condenser, a fractional distillation system, a gas turbine and like consumer unit. l

The web material 2| to be treated by this continuous process is introduced into the chamber I by way of an inlet slot 23, having previously passed between guide means 22, shown schematically as rollers. The material leaves the chamber I through an exit slot 24 and is then directed between similar guide roller means 22.

The inlet slot 23- is covered by a hood 25 having an inlet slit whose edges are formed by cylindrical elements 2S, 21 which allow for the passage of the web ZI while forming a substantially airtight seal against the atmosphere. 'Analogously, the exit slot or end 24 of the chamber is sealed off against the atmosphere by a similar hood 25a whose outlet slit is formed by cylindrical elements 28 and 29.

The spaces formed between the hoods 25, 25a and the outer wall of the chamber I are connected through pipes 30 and BI, respectively, to the exhaust conduit 20 for the purpose of recovering the fluids escaping from the chamber `I by way of the inlet and exit slots 23 and 24.

Admission of any air through the web material into the treatment chamber may be markedly reduced through suction means (not shown) extending into the space adjacent hood 25.

Within the treatment chamber I the material under treatment is moved and displaced within the space defined between the orices of opposite nozzles 4, 5 by means of endless conveyors 32 and 33, guided on rollers 34, 35, which are sufficiently porous or perforated to offer little resistance to the passage of the fluids.

The operation of the apparatus is now described by way of an example, with reference to the drying of a rubberized fabric. A fabric impregnated with a solution of known rubber composition having a benzene base, is especially delicate and diicult to be treated as the mixture of air and benzene vapors is highly inflammable and there is always present the danger of an explosion where such mixtures are allowed to develop. Actually, accumulation of small electric charges resulting from the rubbing or friction of the fabric against a support may be sufficient to produce a detonation or explosion.

According to the invention, the chamber I is heated at the beginning of operations by means of the heating elements I0 and II, the air being simultaneously agitated by fans 6 and 'I. After the temperature has been raised sufficiently to avoid any condensation, superheated steam i's admitted through nozzles I2 and I3 by opening valve I5, the steam gradually replacing vthe air initially present in the chamber I. In this'way, the formation of an explosive mixture during the "subsequent stages of operation will be prevented.

After the air has been driven off or removed from the chamber, or at least sufciently rarefied, thel fabric material 2| impregnated with the aforesaid rubber solution is introduced through the inlet slot 23. Rapid evaporation of the solvent of the rubber composition permeating the fabric material 2| is now brought about by projecting superheated steam at high speed and in the form of individual concentrated jets through nozzles 4 and 5 upon the two faces of the fabric over substantially its entire length within the chamber I, so that this steam will condense both on the surface and in the core or interior of the brous fabric material. Thus, the steam will give up, in addition to its sensible heat, a portion of its latent heat (heat of condensation), resulting in the simultaneous liberation of large calories which in turn will almost instantaneously vaporize the entire solvent present in the portion of the fabric material exposed to the treatment.. This` heat impact drives practically immediately the temperature of the material to the boiling point, even within the fiber cores, which causes instantaneous evaporization of the solvent in the very core of the fibrous fabric, in contradistinction to known methods in which the liquid or solvent is vaporized only after it has been brought up from within the material to the surface thereof through capillary action.

After the operation has been initiated in the manner described, the admission of steam by way of the duct I4 may be throttled or completely stopped.

Thus,v the liquid evaporated from the treated fabric may now be used to form at least part. of the superheated vapor or steam to be projected as a mixture upon the faces of the fabric by the blowers or fans 6 and I which draw on the fluid filling the interior of chamber I, the superheating effect being attained by the action of the heaters I0 and Il.

In order to maintain the atmosphere within the chamber I at a predetermined pressure regardless of the continuous influx or supply of fluid, caused by the evaporation of liquid permeating and impregnating the fabric material 2l and by the admission of steam from the duct I4, the fluid is at least partially evacuated or withdrawn from the chamber by means of exhaust conduit which for this purpose is connected to suitable suction means (not shown) such as blowers, condensers and the like.

It is to be mentioned that it is desirable to maintain a pressure slightly higher than atmospheric inside the chamber I, in order to prevent an-y entry of air from the outside. The danger of air leakage is, moreover, greatly diminished by the provision of the aforedescribed sealsv 25, a at the inlet and outlet ends of the chamber and by the connection between these seals and the exhaust conduit 29 which tends to intercept any air passing through slits 2G, 2l and sibility of an explosive mixture forming inside the chamber I. It should also be noted that the condensation of superheated steam on the surface as well as in the' interior of the treated product, together with the amount of sensible heat given oif by the iiuid, delivers such impact of heat to the material or product under treatment, that the material will be practically instantly brought to the boiling point of the liquid, thereby reducing the drying period very considerably to substantially less than one minute (of the order of not more than a few seconds).

The system described and illustrated may also be used to great advantage in connection with the polymerization of any known polymerizable resinoid-forming substances (synthetic resins) with which fabric is to be impregnated in order to render it wrinkle-proof. 1t is known that it is difficult in such processess to retain in the bers the resinous products dissolved in the liquid phase when the latter is being removed from the fabric by conventional methods. Such methods generally cause rising of the liquid to the surface, by capillary action, before vaporization can take place. This rise of the liquid will in turn result in and entail migration of resinous constituents toward the surface where due to the evaporation thereof a crystalline deposit will be formed which causes a hard and unpleasant feel to the fabric.

To effect the desired polymerization in accordance with the method and by means of the apparatus of the present invention as disclosed above, the air is again expelled from the treatment chamber I by the admission of superheated steam through the duct I4, as above indicated.

The fabric material impregnated with a suitable and known solution of synthetic resin, is introduced into the chamber. The intensive impact of heat produced by the condensation of superheated steam, impinging upon the fabric yand penetrating into the core of the brous layers thereof, instantly brings the material with the impregnating liquid to the boiling point of the latter. This, in turn, results in the instantaneous evaporation of the liquid even from the very core of the fibers, thereby causing in the interior thereof precipitation of the resinoid-forming substance, stabilizing same and effectively preventing its migration. At the same time, the supplied heat will effect the desired polymerization of the precipitated resinous or resinoidforming substances. As in the previously stated example, the operation is extremely rapid and is completed in a few seconds. Also, the quality of the finished and treated material or fibrous product obtained is greatly improved because not only the phenomenon of migration, which characterizes troublesome known forms of treatment, but also the detrimental effects of lengthy exposure to elevated temperatures are avoided. This result is in particular important in connection with the manufacture of paper material sized or impregnated with gelatine, as hereinabove mentioned.

In cases where the treatment involves the sprinkling of the treated material with a particular liquid, the latter may be applied by means of nozzles I6 and l? fed from the conduit I8. The steaming of fabric material may be mentioned as an example of such a treatment; the steaming operation is greatly enhanced by sprinkling the fabric, for example, with a hydrosulte solution during its treatment with superheated steam as hereinabove set forth.

Finally, it should be observed that in. cases where the superheated vapor is steam, the water may be directly introduced into the chamber I by way of the duct I4; it is also possible, however, to admit only saturated steam or vapor and to superheat same inside the chamber by means of the heating elements I0, I I.

The several treatments mentioned above by way of example will make it plain that the invention is Widely applicable to a large number of processes (paper impregnation, fabric drying, etc.), leading now in all cases to various advantages such as increased speed of operation and improvement of the character and quality of the final product. the latter by virtue of the elimination of the detrimental effects due to prolonged exposure to elevated temperatures; all of these advantages being the result of the application and impact of a large quantity of heat resulting from the combined action of the sensible and the latent heat of a superheated vapor allowed to condense on and below the surface of and within the product or material to be treated.

1 kg. `of dry air heated to 100 C. contains 0.3'7X100=37 calories, the heat coefficient being 0.37. In order to evaporate 1 kg. water, 100 calories are necessary for heating the same, whereas 540 calories of latent heat bring about evaporation. To this total of 640 calories are to be added losses due to the radiation and losses which are caused on account of the expulsion of saturated air from the heating chamber at the start of the drying process.

Consequently, at least 1280 calories would be needed for each kilogram of water to be evaporated. .1280 calories are, however, for all practical purposes a low estimate. Certain machines necessitate between three to six times the theoretical quantity of 640 calories. Thus, if it is assumed that the expulsion temperature for saturated air leaving the treatment chamber is 50 C., 1 kg. dry air would yield one half of 37 or about calories. Consequently, one would need 20 60.4 kg. an* of 100 C.

in order to evaporate 1 kg. water.

Superheated steam 1 kg. o1 superheated vapor contains approximately 100 calories for heating purposes and 540 calories latent heat for evaporation to which are added further calories which result from overheating according to the formula Q=606.5 37 (T-t); t being the temperature of the surrounding atmosphere and T the temperature of superheated steam. Consequently, 1 kg. superheated steam of 140 C. contains approximately 640 calories. If one assumes that 15% of the available calories are losses due to radiation, which 15% amount to 96 calories, approximately '736 calories would be available in order to evaporate l kg. of water. Thus,

g=l-l4 kg. of steam is required in order to obtain 1 kg. of water to be evaporated. In practice and in order to be on the safe side, approximately 1.3 kg. of steam should be taken into consideration for each kilogram of water to be evaporated.

From the foregoing it will be seen that there has been disclosed a process of treating lengthy piece of material in continuous operation, comprising the steps of impregnating said material with a reagent in a liquid phase, wherein the reagent may be dissolved or suspended, introducing superheated steam into a chamber, projecting superheated steam upon the surface of said material at a speed sufficiently high to effect penetration of said steam into and below said surface of said material, thereby evaporating at least a portion of said liquid phase, superheating said evaporated portion, and projecting a mixture of said steam and said superheated portion upon the surface of said material, thereby vaporizing a further portion of said liquid phase.

It can thus be seen that there has been provided in accordance with the present invention a method of continuously treating lengthy sheet material to which gelatine containing liquid is applied and which is moved through a substantially air-free enclosure; comprising the steps of maintaining an atmosphere of superheated steam within said enclosure and at a predetermined average pressure slightly higher than atmospheric pressure, directing individual jets of superheated vapor upon spaced surface areas of said material, controlling the velocity of said jets so that the superheated steam is impacted upon the material and partially condenses thereon and sufficient latent heat is removed from the superheated steam to raise the temperature of said material to the boiling point of the liquid contained in said gelatine and substantially immediately vaporized said liquid to force vapor by expansion from said material to the outside thereof, moving the material rapidly through the enclosure at a rate at which the treatment is completed without deleterious effects on the material, evacuating said vapor adjacent and between said surface areas to thereby draw off said vapor therefrom, reheating said evacuated vapor to the conditions of said superheated vapor, and recirculating such superheated vapor for further impact upon said material.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

The method of continuously treating lengthy sheet material to which gelaine containing liquid is applied and which is moved through a substantially air-free enclosure; comprising the steps of maintaining an atmosphere of superheated steam within said enclosure and at a predetermined average pressure slightly higher than asmospheric pressure, directing individual jets of superheated vapor upon spaced surface areas of said material, controlling the velocity 0f said jets so that the superheated steam is impacted upon the material and partially condenses thereon and sufficient latent heat is removed from the superheated steam to raise the temperature of said material to the boiling point of the liquid contained in said gelatine and substantially immediately vaporize said liquid to force vapor by expansion from said material to the outside thereof, moving the material rapidly through the enclosure at a rate at which the treatment is completed without deleterious effects on the material, evacuating said vapor adjacent and between said surface areas to thereby draw off said vapor therefrom, reheating said evacuated vapor to the conditions of said superheated vapor, and Number recirculating such superheated vapor for further 2,060,430 impact upon said material. 2,065,032

JULIEN DUNGLER. 2,119,261 5 2,133,330 REFERENCES CITED 2,193,412 The following references are of record in the 21339586 file of this patent:

UNITED STATES PATENTS lo Number Number Name Date 157,425 1,930,937 Hall Oct. 17, 1933 430,909 2,036,263 Dulken .11 Apr. 7, 1936 Name Date Spooner 1 Nov. 10, 1936 Spooner Dec. 22, 1936 Andrews May 31, 1938 Offen Oct. 18, 1938 McDonaldV Apr. 23, 1940 Andrews Nov. 27, 1945 FOREIGN .PATENTS Country Date Great Britain Apr. 10, 1922 Great Britain June 24, 1935

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