US 3660013 A
A novel treating method and commercial apparatus for carrying out this method have been developed for reacting prepressed cellulosic and cellulosic-blend garments with cross-linking agents in a gaseous phase to impart a durable press thereto. The durable press finish is imparted by placing the garments in a closed chamber typically at room temperature from 70 DEG F to 80 DEG F or, if preheated, at a temperature not in excess of 150 DEG F, adding formaldehyde gas and sulphur dioxide gas and steam for several minutes causing the temperature in the chamber to rise due to the steam, cutting off the steam and allowing the temperature to drop to saturate the atmosphere and cause greater condensation of steam through the garments, and then heating the chamber to a temperature of the order of 250 DEG F to complete the crosslinking operation. Next, the garments may be freed of residual odors by flushing the chamber with fresh air and/or steam. The apparatus comprises an openable treating chamber adapted to be heated as by steam ducts and having therein a heated tray for receiving paraformaldehyde and vaporizing the same. Also, means are provided for introducing controlled amounts of steam and of sulphur dioxide as the catalyzing agent. The chamber has suitable ports enabling it to be flushed by fresh air and by steam.
Claims available in
Description (OCR text may contain errors)
United States Patent Payet et a1.
 METHOD AND APPARATUS FOR PRODUCING A DURABLE PRESS IN GARMENTS CONTAINING CELLULOSE OR CELLULOSIC DERIVATIVES  Inventors: George Louis Payet; John H. Forg, both of Cincinnati, Ohio  Assignee: McGraw-Edison Company, Elgin, Ill.
 Filed: Aug. 1, 1969  Appl. No.: 846,884
FORE1GN PATENTS OR APPLICATIONS 43 7,642 11/1935 Great Britain ..8/116.4 980,980 1/1965 Great Britain ..8/116.4
OTHER PUBLICATIONS Guthrie, Textile Research Journal, Vol 29, pp. 834- 836 (1959) 51 May 2,1972
American Dyestuff Reporter, March 27, 1967, pp. 207- 208 Mehta et al., Journal of the Textile Institute, Vol. 58, ppv 279- 292 1967) Primary Examiner--George F. Lesmes Assistant Examiner-J. Cannon Attorney-George H. Fritzinger  ABSTRACT A novel treating method and commercial apparatus for carrying out this method have been developed for reacting prepressed cellulosic and cellulosic-blend garments with cross-linking agents in a gaseous phase to impart a durable press thereto. The durable press finish is imparted by placing the garments in a closed chamber typically at room temperature from 70F to 80F or, if preheated, at a temperature not in excess of 150F, adding formaldehyde gas and sulphur dioxide gas and steam for several minutes causing the temperature in the chamber to rise due to the steam, cutting off the steam and allowing the temperature to drop to saturate the atmosphere and cause greater condensation of steam through the garments, and then heating the chamber to a temperature of the order of 250F to complete the crosslinking operation. Next, the garments may be freed of residual odors by flushing the chamber with fresh air and/or steam. The apparatus comprises an openable treating chamber adapted to be heated as by steam ducts and having therein a heated tray for receiving paraformaldehyde and vaporizing the same. Also, means are provided for introducing controlled amounts of steam and of sulphur dioxide as the catalyzing agent. The chamber has suitable ports enabling it to be flushed by fresh air and by steam.
9 Claims, 13 Drawing Figures PATENTEmme I972 8,560,013 sum 10F 5 GEORGE L.. PAYET JOHN H. FORG PATENTEDMAY 2 m2 SHEEI 20F 5 @IIIIIIIIIIIIIIHIIIINID INVENTORS GEORGE L. JOHN AGENT METHOD AND APPARATUS FOR PRODUCING A DURABLE PRESS IN GARMENTS CONTAINING CELLULOSE OR CELLULOSIC DERIVATIVES The invention is specifically described in terms of treating garments but is applicable to any cellulosic or part-cellulosic fabric articles of cloth or cloth-like nature including bed linens," tablecloths, curtains, drapes, etc., as well as those of non-woven or felted material such as disposables, i.e., garments made of paper or paper-like material. The term fabric articles" is herein used to comprehend all the items of this general category.
Cellulose fabrics comprise long polymers having attached (OH) radicals which can be reacted with crosslinking molecules between the polymers. These crosslinks permit some slippage between the polymers under stress, but return the polymers to their initial relationships when outside stresses are removed. By introducing such linkages into a cellulose fabric a durable press is obtained. Formaldehyde is well known to produce such linkages when diffused through the cellulose fabrics in the presence of an acidic catalyst, heat and moisture. An example of such a catalyst is sulphurous acid which can be produced in the apparatus from sulphur dioxide and moisture. It is known on a laboratory scale that cotton will crosslink in the presence of steam, formaldehyde vapor and sulphur dioxide gas but it is not known that this method can be carried out dependably and economically on a commercial scale.
An object of the invention is to provide a novel method and apparatus for carrying out this method on garments in an effective and efficient manner to produce a durable press having improved properties.
Another object is to provide a method of imparting a durable press to cellulose fabrics within a sufficiently short time cycle and with lower concentrations of formaldehyde gas and sulphur dioxide gas to render the method practical for commercial use.
Another object is to provide such novel method and apparatus which is adapted for treating individual batches of cellulose or cellulosic-blend clothing under controlled conditions to assure consistently good results.
Another object is to provide an improved method and apparatus for imparting a durable press to cellulosic fabrics, which has a sufficiently low installation cost and short time cycle to render the apparatus practical for commercial use by yard goods stores, garment manufacturers, retail stores and cleaning and dyeing shops.
These and other objects and features of the invention will be apparent from the following description and the appended claims.
In the description of our invention reference is hadto the accompanying drawings, of which:
FIG. 1 is a front vertical section on line 11 of FIG. 3 showing a treating chamber for carrying out the present invention according to one embodiment thereof;
FIG. 2 is a horizontal section on the line 2-2 of FIG. 1;
FIG. 2a is a fractional sectional view to enlarged scale also on the line 2-2 of FIG. 1;
FIG. 3 is a vertical sectional view on the line 3-3 of FIG. 1;
FIG. 4 is a horizontal sectional view through the blower box on line 4-4 of FIG. 1;
FIG. 5 is a fractional sectional view on the line 5-5 of FIG.
FIG. 6 is an exploded diagrammatic view showing an arrangement of heating channels on the back sides of the internal walls of the treating chamber;
FIG. 7 is a fractional sectional view on the line 7--7 of FIG. 3 showing the interconnecting passageways between successive heating channels;
FIG. 8 is a graph showing a typical temperature v. time cycle curve in the treating process by the embodiment shown in FIGS. 1 to 7;
FIG. 9 is a diagrammatic view showing a front elevation with the front door removed of a treating box according to a second embodiment of the invention;
FIG. 10 is a graph showing a typical temperature v. time cycle of the treating process according to the second embodiment of our invention;
FIG. 11 is a side elevational view of two treating boxes in sequential arrangement with a conveyor running therethrough; and
FIG. 12 is a top plan view of this sequential box arrangement.
The embodiment of our invention shown in FIGS. 1 to 7 comprises a treating box 10 for receiving batches of prepressed cotton or cotton-blend clothing 11 and of providing the same with a durable press by the novel treating method of our invention. This is a rectangular box which may for example be similar in outward size and shape to a large upright refrigerator. The box is double-walled and insulated between the walls but has steam heating channels applied against the outer sides of the inner walls for heating the inner treating chamber. The inner walls are preferably made of aluminum and comprise left and right vertical sidewalls l2 and 13 (FIG. 1), a back wall 14 (FIG. 2), a horizontal bottom wall 15 and a slanting top wall 16 which is inclined downwardly from frontto-back as shown in FIG. 3 to avoid dripping of any possible condensation onto the garments being treated. The inner walls are welded airtight at their seams into a unitary upright construction open at the front except for a short wall section 17 depending from the top wall 16. (FIG. 3). The remaining front opening is closed by a door 18 hinge at its left side as indicated at 19. The door overlaps the side edges of the inner walls and is sealed airtight thereagainst when closed by an intervening sealing strip 20.
Applied against the outer side of each inner wall of the box and door 18 is a series of side-by-side semicylindrical channel members 21. These channel members are welded along their edges to each other and to the inner walls of the box except at their end portions. At the end portions alternate pairs of adjacent edges of the channel members are cut away at 22 from the wall of the box and welded only to each other to provide interconnecting passageways between the channel members at the ends thereof. (FIGS. 6 and 7). In this way a continuous duct is formed proceeding zig-zag along each inner wall of the box with the inner wall constituting one side of each duct.
Steam for heating the inner chamber is led via a valve V and a pipe 23 through the back wall 14 near the top of the box and midway the sides thereof. The pipe extends to a point near the front door 18 and then curves upwardly through the top wall 16 to which it is secured airtight by a fitting 24 (FIG. 3). This horizontal portion of the pipe is free of condensation because of its heated condition and serves as a rack on which hangers for the clothing being treated may be attached. The extension of the pipe 23 through the top wall is at a junction between two ducts 21 (FIG. 6) so that the steam will divide between the two ducts on the top wall 16 as indicated by the arrows 25. By way of example, the steam ducts on the several walls may be connected as follows: At the end of the last duct at the right side of the top wall 16 the steam is led via a nipple 26, connecting tube 27 and nipple 28 to the first duct at the top of the side wall 13; at the end of the last duct at the bottom of the side wall 13 the steam is led by a nipple 29, connecting tube 30 and nipple 31 to the first duct at the top of the back wall 14; and at the end of the last duct at the bottom of the backwall 14 the steam is led back to the source via a nipple 32, tube 33 and intervening trap 34. Similarly, at the end of the last duct at the left side of the top wall 16 the steam is led via a nipple 3S, flexible tube 36 and nipple 37 to the top duct on the door 18; at the end of the last duct at the bottom of the door 18, the steam is lead via a nipple 38, flexible tube 39 and nipple 40 to the first duct at the top of the left side wall 12; and at the last duct at the bottom of the side wall 12 the steam is led back to the source via a nipple 41, tube 42 and intervening trap 43. The bottom wall similarly could be steam heated if desired.
Applied against the outer side of the ducts 21 are layers 44 of asbestos paper, and applied against the asbestos paper are layers 45 about PA inch thick of fiber glass having its aluminum side facing outwardly for the purpose of providing a smooth unimpeded surface for air flow. Spaced about 1% inches from the fiber glass are the respective walls of an outer steel shell 46. This shell has a flanged front edge 47 in a vertical plane which closes the space between the shell and inner walls at the front of the box along the sides and bottom thereof. Also, there is a horizontal flanged edge 48 between the lower portion of the top wall section 17 and the confronting portion of the shell. The door 18 underlies the horizontal flanged edge 48 and is sealed against the vertical flanged edges 47 at the bottom and sides of the door and against a lower strip of the wall 17 below the flanged edge 48 at the top of the door.
Just beyond the sides, top and bottom of the door 18 there are small slots or openings 49 in the flanged edge 48, and at the top of the door there is a series of openings 50 in the horizontal flanged edge 48. These openings allow air to be drawn inwardly past the side edges of the door 18 responsive to an exhaust blower 51 connected by a pipe 52 at the back of the box to the space between the inner walls and shell 46. This suction blower draws away gases which may leak from the box past the seal of the door to prevent these gases from escaping into the room in which the treating box is located. The chance of any gas leakage is kept however at a minimum by a latch 53 diagrammatically indicated in FIG. 2, which holds the door closed with pressure against the seal when the latch is locked.
Centrally located on the bottom wall 15 of the treating box is :1 formaldehyde reactor comprising a shallow rectangular case 54 having an inset top wall 55 forming a tray for receiving a quantity of solid paraformaldehyde. This case 54 contains electric heating coils 56 connected by an outgoing cable 57 leading through an opening 58 in the bottom wall 15 to a voltage supply. The case 54 is secured by bolts 60 to the bottom wall 15. The space between the electric heating coils and the bottom wall 15 is filled with a fiber glass insulation 61. This reactor is adapted to heat the solid paraformaldehyde in the tray 55 and vaporize the same during a treating operation.
Extending through a side wall of the box at a level above the tray 55 is a pipe 62 connected to a source 64 of sulphur dioxide (S0,) through a solenoid valve 65. Also, in each side wall 12 and 13 at a level above the tray 55 is a pipe 66 terminating flush with the inside surface of the side wall. These are connected to a source 67 of steam through a solenoid valve 68. A drain pipe 69 and valve 70 leading from the bottom wall of the chamber permits any water condensation to be drained after each press cycle.
In the walls of the box near the upper part thereof are portholes 71 and 72. These portholes are lined by walls 71a and 72a extending inwardly from the outer shell through the inner side walls of the box. Overlying these portholes are respective spiders 73 and 74 secured as by bolts to the inner walls 12 and 13. Mounted on the central hubs of these spiders are air cylinders 75 and 76 having armatures extending inwardly through the portholes and carrying respective dampers 77 and 78 at their inner ends. The damper 77 comprises a circular metal plate 770 as of stainless steel, a disk 77b as of silicone sponge applied to the metal plate and a disk 77c of solid silicon rubber applied to the sponge disk (FIG. 2a). Similarly, the damper 78 comprises the corresponding parts 78a, 78b and 78c. The dampers stand normally open (FIG. 2) and are closed and opened by air pressure to the air cylinders (FIG. 1). In the walls of the portholes are openings 71b and 7211 through which air is drawn inwardly responsive to the suction blower 51 so that any gas leakage past the dampers 77 and 78 when the dampers are closed may not escape into the atmosphere.
In the backwall of the box near the bottom thereof is a rectangular opening covered by a damper box 79 (FIGS. 1, 3, 4 and 5) having a rim flange 76 bolted to the outer shell. This damper box has a porthole 80 in its back wall near one end thereof coupled by a duct 81 to a suction blower 82. This blower has an outlet duct coupled by a stack 83 to the outside. The back half of the damper box is divided from the front half by a partition wall 84 having a porthole 85 therein at the other end of the damper box. This porthole is closed by a damper 86 (such as the dampers 77 and 78) secured to the armature 87 of an air cylinder 88 bolted to the back wall of the box (FIG. 4). Operation of the air cylinders 75, 76 and 88 in an inward direction open these dampers (FIG. 1) to enable the blower 82 to draw the gases from the treating chamber and to circulate air therethrough. To permit any rising pressure in the treating box to be relieved when the pressure reaches a predetermined level, as when steam and sulphur dioxide are injected into the box, a blow-off valve 89 is provided in the damper box 79. This valve comprises a tube 90 extending through the partition wall 84 and having a tumed-up end portion at the outer side of the wall 84 closed by a weighted cap 91 resting on the end of the tube. The cap has an internal silicone rubber gasket 92 to provide a good seal so long as the pressure is below the blow-off level.
The present method is carried out by placing the garments in the closed chamber and then injecting formaldehyde and sulphur dioxide gases and steam. During the injection of these gases the chamber is not heated other than by the heat of the steam. The initial temperature of the chamber may be at room temperature, say 70 to 80 F., or the chamber may be preheated but not in excess of 150 F. The steam is then cut off and the chamber allowed to cool to saturate the treating atmosphere and cause a greater condensation of steam through the fabrics being treated. When the box is initially at room temperature the steam is injected until the internal temperature reaches approximately F., whereupon the steam is cut off and the chamber allowed to cool typically from l0 to 25 F. If the chamber is in a preheated condition i.e., above room temperature not in excess of F. the temperature may be allowed to cool after the steam is cut off by more than the temperature rise due to the steam before the auxiliary heating is applied. By proper timing of the auxiliary heating, depending upon the type of auxiliary heating apparatus, the internal temperature is raised following the temperature drop just noted to a temperature of the order of 250 F. to complete the crosslinking operation. Thereupon, the chamber is allowed to cool and outside air is circulated through the chamber for several minutes to rid the garments of residual odors. Also, if necessary, steam may thereafter be circulated through the chamber for several minutes and then again outside air for several minutes to rid the garments wholly of any residual odors.
In a more precise procedure for carrying out the above method by the treating apparatus above-described, con sistently good results are obtained starting with the treating chamber at or about room temperature and with the reactor heater for the paraformaldehyde in a preheated condition but not to full vaporizing temperature. The garments to be treated are then placed on coat hangers attached to the pipe 23, the desired quantity of paraformaldehyde is placed on the tray 55, the reactor heater is turned up to full temperature, and the door 18 and all dampers are closed. Low pressure steam of approximately 4 p.s.i. is then admitted via the pipe 66 and sulphur dioxide gas is admitted via the pipe 62 for a period of approximately 2 minutes during which time the paraformaldehyde is being vaporized. During this period the steam, sulphur dioxide and formaldehyde gases permeate through the fabrics and the temperature in the chamber rises because of the steam typically to about 120 F. This is shown by the first portion A of the curve of FIG. 8. The time for carrying out this operation is typically about 2 minutes. At the end of this period the steam valve V is opened to start heating the chamber. However, since the steam ducts 21 are outside the chamber walls, there is a delay in heat transmission into the chamber causing the internal temperature to fall about 25 in the next 2 minutes as shown by the second portion A of the curve of FIG. 8 before the temperature begins to rise from the auxiliary heating. This temperature drop is a very important step in the present invention because it causes the treating atmosphere to become saturated with a resultant greater condensation of steam through the fabrics being treated. This greater condensation reduces the required concentrations of formaldehyde and sulphur dioxide and shortens the treating cycle. At the end of the 2 minute temperature drop the heat from the steam ducts 25 causes the internal temperature to begin to rise. This rise continues for a period of about minutes as shown by the portion A of the curve of FIG. 8 before the temperature reaches 250 F. to complete the crosslinkage operation. The time required to bring the temperature to 250 F. is important only from an economy standpoint since the completion of the linkage reaction depends only on the temperature reaching the 250 P. value. Accordingly, a time is selected taking into account the usual steam source, thermal mass of the box, etc., which enables the box temperatures to be increased to 250 F. or thereabout in a period comensurate with practical requirements and with maximum economy. When the temperature reaches 250 F. the steam valve V is turned off preferably by automatic control from the thermostat T in the chamber and the garments are purged by air and optionally also by steam to remove the residual odors.
The amounts of formaldehyde and sulphur-dioxide for each treating operation depend by the present invention on the volume of the treating chamber. For example, the volume of the treating chamber may be approximately 35 cubic feet. In terms of percentage by volume at atmospheric pressure the sulphur dioxide range is typically from 0.1 percent to 2 percent, and the formaldehyde range is from 2 percent to 10 percent. This volume range of formaldehyde is obtained by placing paraformaldehyde on the tray 55 in an amount from 26.25 grams (2 percent) to 131.1 grams (10 percent). However, for maximum results, the sulphur dioxide is provided at a volume percentage of 1.02 percent and the formaldehyde at 6.19 percent. This volume percentage of formaldehyde is obtained by placing 80 grams of paraformaldehyde on the tray 55. The maximum points in these ranges should not be exceeded because more than 2 percent sulphur dioxide will cause undue degradation of the fabric, and concentrations of formaldehyde above the range noted provides an explosive hazard.
The amount of moisture required for each treating operation is dependent primarily on the weight of the cellulose in each batch of garments being treated. If the clothing being treated is all cellulose the total weight of the batch is considered in determining the amount of moisture required. However, if the clothing is a blend of a given percentage of cellulose with another fiber, then only that percentage of the overall weight is considered in determining the amount of moisture required. It is desired that the moisture content of the clothing should reach from 10 percent to percent on a weight basis during a treating operation, but preferably the moisture content is to be held between 15 percent to 17 percent. A variable injection of steam into the treating chamber is achieved by controlling the time interval the steam valve 68 is held open during each treating operation. For this reason the solenoid valve 68 is controlled by a timer 94. This timer has a time setting knob 95 registering with a scale 96, and has a start button 97 for starting a treating operation and a start button 102 for starting a purge operation, as later described. The timer is connected to a power supply via a connector cable 98 and is connected to the solenoid valve 68 by a connector cable 99. Upon placing a batch of clothing in the treating chamber and then closing the door 18 the operator will press the start button 97 to start the flow of steam into the treating chamber for an interval depending upon the setting of the knob 95. The sale 96 may be calibrated in terms of the weight of cotton cloth in the batch being treated so that the operator after weighing a batch can readily set the knob for the right steam injection.
The timer 94 is also connected by a cable 100 to the sulphur dioxide control valve 65 to energize this valve for an internal independent of the setting of the knob 95 each time the start button 97 is pressed. However, this time interval of energization of the valve 65 may be adjusted to the desired setting for any given size of treating chamber by an adjusting screw 101 preferably as by a tool such as a wrench or screw driver.
The purging of the garments to rid them of residual odors is carried out by first replacing the gases in the treating chamber with room air as by opening the dampers 77 and 78 at the sides of the treating chamber, opening the damper 86 of the damper box 79 and starting the exhaust blower 82. After the exhaust blower 82 has run from 3 to 5 minutes to replace the gases in the treating chamber with outside room air, the garments may be removed. However, if further purging is required the dampers are closed to seal the treating chamber and the steam purge button 102 on the timer 94 is pressed to open the steam valve 68 without however opening the valve 65 controlling the sulphur dioxide gas. The timer 94 is adapted to hold the steam valve 68 open for a period of from 2 to 5 minutes when the purge button 102 is pressed. After the treating chamber is again exhausted from 2 to 5 minutes as above-described, the batch of clothing may be removed. Still further, the cycle of adding steam and of then exhausting the treating chamber may be repeated.
Extensive tests have shown that garments treated by the present method have a durable press with improved properties as follows:
Durability of crosslinks to acidic washing is superior to that found in conventional resinous type durable press. This is shown in Table I by the crease recovery for acid souring vapor phase treated samples and conventional resinated samples of the same type where the Symbol (W+F) means the recovery along the warp plus the recovery along the fill, it being understood that complete recovery in each direction would be Softness of hand is much greater than in conventional resin type durable press as there is no surface resin to give the fabric a harsh handle.
Retention of hand on successive washing As there is no surface resin which is subsequently washed off, vapor phase treated fabrics retain their handle after numerous washings, whereas conventional resin type durable press becomes softer and softer after nominal washings.
Superior Abrasion Resistance of vapor phase samples is due primarily to the softer hand, as the fabrics have not been embrittled with resins as in the case of resin type durable press. As an example, two like fabrics were compared, one containing conventional resin type durable press, the other the vapor phase treatment. These samples are shown in Table 11.
TABLE II Abrasion loss of fiber weight in accelerator at 3,000 R.P.M. for 3 minutes Original Final Percent Percent weight weight fiber fiber Sample number (grams) (grams) retained lost 619P conventional 3. 8791 3.1690 81. 7 18. 3
durable press. 6181 vapor phase durable 3. 0803 3. 4217 85. 8 14. 2
Both good wet and dry wrinkle recovery is evidenced in vapor phase durable press fabrics as shown in the following Table III.
TABLE I1I.-WE'I AND DRY GREASE RECOVERY Dry creasc recovery Wet crease recovery Sample No. W. F. (W.+F.) W. F. (W.+F.)
6181 (vapor phase) 155. 160. 0 315.0 152. 0 156. 3 308. 3 6101 (durable press) 150. 0 154. 3 304. 3 132. 3 143. 0 275. 3
TABLE IV Stain removal on resin durable press vs vapor phase durable press Chocolate Catsup syrup Sample number Salad dressing Number Treatment washes woamww impala.
Ratings f0r s0il removal are as follows: 1, no change; 2, slight change; 3, one, half stain; 4, stain not quite gone; 5, stain completely removed.
Alteration capabilities are very simplified where vapor phase treatments are employed, as garments may be altered prior to rendering the fabric durable press. In conventional resin type durable press, the alterations must be made after the garment is rendered durable press. Creases are then durable and cannot be changed as alterations require.
in the alternative embodiment of the invention shown in FIGS. 9 and 10, the same form of temperature-time relationship during the treating process is obtained to effect the same durable press with the use of lesser concentrations of treating agents than has been heretofore obtainable and again the period of each treating operation is substantially reduced. In this embodiment, the steam ducts 21 and insulation 45 are removed from between the internal chamber walls 12-14 and 16 and the outer shell 46, and instead the inside walls 12-14 and 16 are covered with a l-inch thick insulation 108 of expanded silica known as Careytemp, and a series of finned steam-operated heater units 109 are mounted on the inside walls against the insulation 108. These internal heating units 109 may comprise three vertically spaced units on the back wall 14 and three intervening units on each side wall 12 and 13. No heating units are placed against the top and bottom walls 15 and 16 or against the door 18.
Since the heating units 109 are inside the chamber to heat the internal atmosphere directly they are capable of heating the treating chamber with relatively little time delay. Accordingly, in carrying out the treating process starting with the chamber at room temperature, the formaldehyde and sulphur dioxide gases and the steam are provided in the chamber for about 2 minutes causing the internal temperature to rise again to about 120 F. from the heat of the steam, as shown by the portion A of the curve of FIG. 10. Next, the steam injection is cut off and the chamber is allowed to cool for about 2 minutes without any auxiliary heating applied. This causes the temperature to fall as shown by the portion A; of the curve of FIG. 10. This fall may typically be from 10 to 15. The steam is then turned on the heating units 109 causing the internal temperature to begin to rise immediately as shown by the portion A of the curve of FIG. 10. Further, since the heating units 109 are directly in the chamber the internal temperature rises to about 250 F. to complete the crosslinkage reaction in only about 6 minutes. Thereupon, as before, this steam is cut off from the heating units 109 and the chamber is allowed to cool. Also, the fabrics may then be purged with room air and/or steam to rid them of residual odors as may be required.
1. The method of producing a durable press in a fabric article containing cellulosic material, which comprises placing said fabric article in a closed chamber, providing in said chamber formaldehyde gas, steam and sulphur dioxide gas causing the temperature in the chamber to rise due to the heat of the steam, cu ing off said steam to allow the temperature in said chamber to drop and cause greater condensation of steam in said fabric article and thereupon heating said atmosphere after cut off of said steam to raise the temperature in said chamber to a value of the order of 250 F.
2. The method set forth in claim 1 including the step of circulating air and/or steam through said chamber after the chamber reaches said 250 F. temperature whereby to rid the fabric articles of residual odors.
3. The method set forth in claim 1 wherein the amount of sulphur dioxide gas provided in said chamber is from 0.1 percent to 2 percent by volume of the gases in said chamber at atmospheric pressure.
4. The method set forth in claim 1 wherein the amount of formaldehyde gas provided in said chamber is from 2 percent to 10 percent by volume of the gases in said chamber at atmospheric pressure.
5. The method of producing a durable press in a fabric article which contains cellulosic material and has been pressed, creased or finished as desired, which comprises placing said fabric article in a closed chamber, providing formaldehyde and sulphur dioxide gases in said chamber and providing simultaneously steam in said chamber causing the temperature in the chamber to rise and said fabric article to be permeated with moisture, cutting off the steam and allowing the temperature in said chamber to drop and cause greater condensation of steam in said fabric article, and then heating the atmosphere in said chamber to a temperature of the order of 250 F.
6. The method set forth in claim 5 wherein the temperature in said chamber is initially at room temperature.
7. The method set forth in claim 5 wherein said heating is effected indirectly through the chamber walls.
8. The method set forth in claim 5 wherein said heating is effected directly in the chamber.
9. A method of treating garments or other fabric articles made of cellulosic or part cellulosic materials pre-pressed, creased or finished as desired, comprising placing said garments or other fabric articles in chamber wherein the temperature is F or below, closing said chamber, introducing steam therein to impart a predetermined moisture content to said garments or other fabric. articles, concurrently introducing a predetermined amount of sulphur dioxide and a predetermined amount of formaldehyde gas by vaporizing paraforrnaldehyde in said chamber, cutting off the steam and allowing the temperature to drop by a predetermined amount to cause greater condensation of steam in said garments or other fabric articles, and nextapplying dry heat to raise the temperature in said chamber to about 250 F. whereby wrinkle-resistant, press-free properties are imparted to said garments or other fabric articles by a crosslinking reaction in the cellulosic material thereof.