Process For Treating Textile Materials

Abstract

A process and apparatus are described for impregnating a textile having relatively fine openings therein with a treating liquid whereby penetration and pick-up of the liquid are improved by relatively strong vacuum degassing the textile immediately before impregnation.

Parent Case Text

This application is a continuation-in-part of copending application Ser. No. 665,894, filed Sept. 6, 1967, now abandoned, and also of co-pending application Ser. No. 746,972, filed July 23, 1968, the latter application being a continuation-in-part of the former.

Description

The present invention is concerned with the treatment of textile materials with liquids.

In the textile industry, impregnation of a sheet-like or web-like textile material (e.g. a woven, nonwoven or knitted fabric) with treating liquid is often performed by repeated dipping and squeezing. For liquid of low viscosity and fabric or other material of relatively open structure, it is comparatively easy to achieve good impregnation. However when textile materials having relatively fine openings therein are involved, such as a tightly woven fabric, impregnation into the textile structure becomes increasingly difficult as the liquid must be forced into spaces between adjacent fibers or filaments which are occupied by air molecules. Previously proposed techniques usually involve dipping the textile into a vessel containing the liquid and then squeezing it between two pressurized rubber rollers. This process is repeated as many times as necessary to achieve the desired impregnation.

The principal object of the present invention is to provide a process which greatly improves the impregnation of textile materials having relatively fine openings therein with liquids. Other objects and advantages will be hereinafter apparent.

Broadly stated, the present process comprises degassing the textile by means of a relatively strong vacuum, i.e. removing the gases and vapors entrapped therein, just before the textile is subjected to liquid treatment. According to the invention, the desired degassing is accomplished by passing the textile through a chamber having a strong vacuum therein. When the thus processed textile is then contacted with the treating liquid, there is a pressure gradient between the liquid and the textile whereby the liquid, for all intents and purposes, is forced into the void spaces in the textile created by the vacuum treatment. Whatever the actual mechanism may be, however, it is apparent that application of the strong vacuum to the textile immediately prior to the impregnation with liquid brings about a much more effective impregnation than would otherwise be possible without using a strong vacuum for degassing the textile.

The invention is particularly valuable when "textile piece goods" are used as the textile material being impregnated in a continuous process. Textile piece goods have fine openings or interstices therein, as could be used, for example, for suitings and shirtings, as is understood in the art. Such textile piece goods ordinarily come in relatively short lengths (for example, in the order of normally 60 - 150 yards each) and have joints therein between adjacent sections (which joints commonly extend transversely of the length of the textile piece goods), joining a plurality of pieces or sections into a larger continuous length for further processing, such as dyeing or finishing. The invention is also particularly valuable when relatively low viscosity liquids are utilized as the impregnating liquid for such textile piece goods.

The invention is described in more detail by reference to the accompanying drawings wherein:

FIGS. 1, 2, 3, 5 and 6 illustrate schematically various different exemplary forms of apparatus for practicing the invention.

FIG. 4 is a fragmentary and enlarged perspective view of exemplary means for adjustment of sealing rollers for use herein, as will become apparent.

Referring now to the drawings wherein like or corresponding parts have been given the same or similar reference numerals, the apparatus shown in FIG. 1 comprises a rigid box member 2 which serves to define the degassing zone or vacuum chamber 4. Member 2 may be constructed of stainless steel or other metal as will be understood by those in the art.

Member 2 is provided with a first opening 6 and second opening 8 constituting the entrance opening and exit opening, respectively, for the web or sheet of textile material 10 moving in the direction shown by the arrows. As indicated above, the textile 10 has relatively fine openings therein and is of the type of textile where air spaces may occur between adjacent fibers or filaments and impregnation is normally effected with difficulty. Such textiles include, for example, woven or knitted fabrics, nonwovens and tufted nonwovens. So-called textile piece goods, as referred to above, are characteristic of a preferred type of known textile web or sheet with which the present invention is particularly useful. As typical examples of materials which may be advantageously treated by the present process, there may be mentioned any knit, woven or nonwoven construction comprising natural and/or synthetic fibers, e.g. wool, cotton, glass, polyester, acrylic, rayon, etc.

Suitable sealing means for maintaining the vacuum within the chamber 4, while permitting entrance and exit of the textile therefrom, must also be provided for present purposes. These sealing means may take a variety of forms but a particularly preferred embodiment herein, as shown in FIG. 1, involves the use of pairs of entrance and exit rubber sealing rollers 12 and 14 respectively, mounted adjacent the entrance and exit ends of chamber 4 and cooperative with plate members 16. The latter members 16, in one exemplary form, are steel-backed, Teflon-coated rubber flaps used as a sliding seal for the pairs of rubber rollers 12 and 14.

These pairs of rollers 12 and 14 serve to guide the movement of the textile in and out of the chamber 4 while effectively maintaining the vacuum in the chamber. Resilient seal rollers of this type are well known in the art and any available design thereof may be used for present purposes. See also, U. S. Pat. Nos. 3,137,151 and 3,213,470 disclosing seals suitable for use herein.

The seal rollers 12 and 14 are rotated simultaneously at the same surface speed in the direction of the arrows so as to draw the textile 10 through chamber 4. This may be accomplished by appropriate motor means 17 which function to drive one each of the pairs of rollers 12 and 14 through a suitable driving chain arrangement 18, as indicated, each of the other rollers 12 and 14 being rotated by contact with its chain-driven mate. The speed of rollers 12 and 14 is regulated to subject the textile to degassing for the desired length of time. It will be recognized that the time the textile spends in the degassing or vacuum chamber can be widely varied and will depend on other operating conditions, e.g. the nature of the fabric involved. Typical exposure times may range from about 1 - 15 seconds, for example, 2 - 5 seconds, although times outside this range may also be effectively used. Advantageously, conventional means (not shown) are provided for heating the chamber 4, e.g. infrared, dielectric, radiant and other types of heaters, so as to increase the temperature of the textile and thus improve the efficiency of the degassing treatment.

The chamber 4 may be evacuated to the desired degree of vacuum by means of a conventional high capacity vacuum pump or the like (not shown) through an appropriate takeoff conduit 19. The vacuum in chamber 4 is advantageously high or strong, for example, in the range of 80 - 98 percent of a complete or perfect vacuum, that is, about 0.6 - 6 inches of mercury, absolute pressure. In an exemplary and preferred embodiment the vacuum in chamber 4 is at least 80 percent of a complete or perfect vacuum and could go as high as 95 percent or higher.

In the embodiment of FIG. 1, the top nip of the exit seal rollers 14 is filled with treating liquid 20 so that immmediately after being degassed in chamber 4, the textile is drawn through the rollers 14 and the liquid 20. The textile is shown as thereafter passing through a set of conventional padder rollers 22 or an extractor or any other suitable means, if needed, to remove any excess liquid from the textile, and then over guide roll 24 to any desired subsequent treatment, as will be understood. One of the padder rollers 22 is shown as being driven by means of motor 17 and the chain means 18.

The apparatus of FIG. 2 is identical to that shown in FIG. 1 except that, in FIG. 2, the upper portion of the box member 2 is extended to provide a larger box-like liquid treating zone or tank 26 which may contain as much treating liquid 28 as desired. This arrangement makes it possible to provide as long a passage of the fabric through the treating liquid as may be desirable or necessary and has the advantage of permitting the use of greater volumes of treating liquid than possible where the liquid is in the nip of the top seal rollers as in FIG. 1.

In the system of FIG. 3, the rotating seal rollers 12 and 14 of FIG. 2 have been replaced by fixed or non-rotating pairs of seals 29 and 30. These may comprise, as shown, cooperating elastic or flexible sealing members which are sufficiently flexible to permit passage of the fabric 10 therethrough while maintaining the desired vacuum condition in chamber 4. The seals 29, 30 are shown as being of the inflated seal type, in pressure contact with the fabric or textile as it passes therethrough, thus inhibiting passage of atmosphere or liquid from tank 26 into the chamber 4.

FIG. 4 diagrammatically shows one arrangement for maintaining the desired sealing contact between each set or pair of sealing rollers 12 and 14 in the FIG. 1 and FIG. 2 embodiments. The arrangement, as applied to the top sealing rollers 14a and 14b is shown as comprising a hand crank 32 or the equivalent, and shaft 33 rotatable therewith as indicated, to operate a spring loaded cam arrangement, broadly identified by the numeral 34, for the purpose of sliding the movable roller 14a on bar members 36 towards the other roller 14b, the latter being held in a fixed position, to provide the desired seal while permitting passage of the fabric through the rollers. Similar adjusting means may also be provided at the other end of the rollers (now shown). It will be appreciated that other means for maintaining the rollers in the desired sealing contact, e.g. air pressure, may also be used.

The degassing effect on the textile and the fibers and/or filaments therein, when exposed to the high vacuum condition in chamber 4 has been found to result in removal of substantially all gaseous or atmospheric impedance to thorough and immediate wetting or impregnation of the textile. Under conditions of vacuum and temperature combinations within the vacuum chamber 4, entrapped or residual or uneven moisture content has been found to be readily removed.

It has been found further that the pressure differential existing between the vacuum chamber 4 and the chamber containing the impregnating or treatment liquor, exerts a substantial influence on the successful and effective impregnation realized by the subject process.

In the process of the invention, when the textile 10 emerges from the vacuum chamber 4 into direct contact with the treatment liquid at atmospheric pressure, in the FIGS. 1-3 embodiments, the pressure differential is substantial because of the extremely high vacuum conditions within the vacuum chamber. As indicated, this pressure differential has been found to be most effective in bringing about thorough and complete impregnation of the textile. This pressure differential may be still further increased and made more effective, if desired for certain applications, by means of the embodiment of the invention shown in FIG. 5. In this embodiment, the treating or impregnation chamber 26' is made fluid-tight for pressurizing. For this purpose, a pair of rotating, pressure, rubber sealing rollers 50 are arranged at the exit side of the treatment chamber 26' and in suitable sealing contact with structure at the upper end of the walls thereof, whereby the entire chamber within tank 26' is fluid-tight or hermetically sealed.

In the FIG. 5 embodiment, it will be noted that the seals 29', 30' at the entrance and exit ends respectively, of the vacuum chamber 4' are shown as being of the inflated seal type. It will be understood, however, that rotating seal rollers (or other equivalent structures) may be utilized in lieu thereof, if desired, and of the type shown in FIGS. 1 and 2. The textile material 10' is shown as passing over a plurality of rollers 52 within the vacuum chamber and suitable heating means may be provided to raise the temperature of the vacuum chamber, if desired.

When the textile leaves the vacuum chamber 4', it passes immediately into contact with the impregnating liquid in the treatment chamber or tank 26', as shown, after which it passes around the roller 54 and up through the liquid and to be discharged through the exit sealing rollers 50.

In the embodiment of FIG. 5, the vacuum chamber is capable of having a vacuum of from about 0.6 to 6 inches of mercury, absolute pressure, provided therein. The pressure within the treatment chamber or tank 26' is superatmospheric and, for example, in the range of up to about 40-50 p.s.i. Tank 26' may be pressurized in any suitable manner, as by the introduction of fluid under pressure through conduit 56 opening thereinto and communicating with a source of fluid at the desired pressure.

Thus, it will be seen that when using the same high vacuum for the vacuum chamber 4' in FIG. 5, as previously noted herein, the pressure differential between the treating chamber 26' and the vacuum chamber 4' in FIG. 5 will be considerably greater than in the FIGS. 1-3 embodiments, thereby increasing and maximizing the effect of pressure differential in the impregnation step.

The FIG. 5 embodiment does provide a system whereby impregnation liquors may be applied at reduced or elevated temperatures, as may be advantageous in certain applications. Furthermore, it provides a system wherein the impregnation liquors may be applied in a fully closed system, thus avoiding the escape of fumes or gases into the atmosphere. As the overpressure in the treatment chamber 26' in FIG. 5 may be effected by suitable injection or introduction into that chamber of steam, inert gases, or other suitable fluid, this system may be effectively applied where oxygen or other atmospheric gases are sought to be eliminated from the impregnation stage of the process.

FIG. 6 shows a still further embodiment of the invention wherein the treating liquid chamber 26" is pressurized as in the case of the FIG. 5 embodiment. In this case, however, provision is made for the further treatment of the textile with a treating gas, under pressure, after the textile has passed through the impregnating liquid. As shown, the textile first passes through the vacuum chamber 4", through the entrance 29" and exit 30" seals therein and then through the impregnating or treatment liquid 28" which is under superatmospheric pressure, for example, up to about 40-50 p.s.i., as in the case of the FIG. 5 embodiment. The textile 10" then passes from the impregnating liquid 28" into the larger chamber 59 in fluid-tight tank 60 with which it is in open communication. A pair of squeezing nip rollers 22" is shown above the impregnating liquid in tank 60 for the passage therethrough of the textile. A plurality of cloth carrying rolls 62 is shown arranged in tank 60 for directing the passage of the textile through chamber 59, as indicated, the textile exiting through sealing means 50', shown to be of the inflated type.

The chamber 59 may be pressurized through the injection thereinto of steam or suitable reactant vapor or air, for example, through conventionally valved inlet ducts indicated by reference numeral 64.

An inlet 66 is shown opening into the jacketed vessel or tank 26" for the introduction of treatment or impregnating liquid thereinto and with suitable valving (not shown) provided in that line. The jacketing of the tank 26" will control the temperature of the treatment bath, as will be evident.

Line 19" is shown communicating with the vacuum chamber 4" for producing the desired strong vacuum therein, of the same order of magnitude noted above.

The entrance 29" and exit 30" seals for the vacuum chamber 4" are shown as being of the inflated seal type but they may also be of the rotating seal type, if desired, as in the FIGS. 1 and 2 embodiments, or other equivalent sealing structures may be utilized therefor.

The pressurized reaction chamber 59 may be provided with suitable jacketing or insulation (not shown) for temperature control and it will be seen that the vacuum chamber 4" and liquid containing chamber 26" are formed therewithin, providing a simplified and compact unitary construction.

A liquid chemical reaction bath 68 is shown in a tank 70 in the reaction chamber 59, disposed so as to permit the passage of the textile therethrough for additional processing of the textile, as will be evident. The textile will make two passes through that bath 68 in the manner shown, it being evident that the number of passes therethrough may be changed as desired.

Thus, it will be seen that the embodiment of FIG. 6 retains all of the advantages of the FIG. 5 embodiment and includes the additional advantages of providing a substantially enlarged pressure reaction chamber in which more complex reactions might be carried out and completed, as desired, as through the use of gaseous materials introduced into chamber 59. Furthermore, it provides the option of a still further liquid reactant application, in bath 68, within the system.

The process described herein may be used for any type of liquid treatment where good penetration or impregnation into the textile is normally difficult to obtain. Thus, for example, the process may be employed for dyeing, resin treating, mercerizing, scouring and the like, wherein a relatively low viscosity treating or impregnating liquid is utilized. Representative operations, which are given only for the purpose of illustration, are described in the following examples, wherein percentages are by weight.

Example 1

A tight weave cotton/nylon raincoat fabric was threaded up in the manner shown in FIG. 1. The fabric was subjected to vacuum degassing in chamber 4 at ambient temperature and at about 4 inches of mercury (absolute pressure) for about 2 seconds. The treating liquid 20 on the top nip of the exit sealer rollers 14 was a solution of direct dyestuff in water (Sky blue FF, 0.5 grams per liter of water). The fabric was passed from the degassing chamber through the dyebath 20 and the padder rollers 22 and a wet sample was then cut off and immediately weighed. A control sample was treated in the same manner except the application of the vacuum was omitted. The two samples were then dried so as to be in equilibrium with atmospheric conditions and reweighed. The advantage of dyeing by vacuum degassed impregnation was shown by the following:

Control Vacuum Degassed Sample Sample Weight of fabric wet 64.8 gms. 76.3 gms. Weight of fabric dried 49.0 gms. 46.1 gms. Weight of water 15.8 gms. 30.2 gms. % pick up 32.2% 65.5%

As will be apparent, the process with vacuum decreasing increased the wet pick up by more than 100 percent and the vacuum degassed sample was dyed to a much darker blue as shown by spectrophotometric measurements, the shade being 112 percent stronger with vacuum degassing than without.

Example 2

Example 1 was repeated except that the dyestuff was a dispersed dye, the dyebath including the following:

1 percent Cellathrene Brilliant Blue FFS (Color Index No. 61505)

0.1 percent Blancol N (Anionic dispersing agent)

20 percent Keltex (2 percent aqueous solution of sodium alginate)

As in Example 1, two samples were prepared, one with vacuum degassing and one without. The two samples were dried at 150.degree.F., thermosolled for 2 minutes at 370.degree.F on a pin frame and then subjected to treatment for 15 minutes at 160.degree.F in an aqueous stripping solution containing the following:

sodium hydroxide 1 gram per liter sodium hydrosulfite 2 grams per liter Aerosol OT (detergent) 1 gram per liter

The samples were then rinsed and steam pressed. The vacuum sample was much darker blue (i.e. about 28 percent stronger) than the sample which had not been vacuumed.

Example 3

Example 2 was repeated except that, instead of treating the samples in stripping solution, they were washed in an aqueous solution containing 0.5 percent sodium carbonate and 0.1 percent Aerosol OT. The samples were washed for 5 minutes at 140.degree.F in this solution, rinsed and steam pressed. The vacuumed sample demonstrated a much better shade than the non-vacuumed sample.

Example 4

a. A piece of heavy weight textured fiberglass fabric was treated as in Example 1 using the system shown in FIG. 1 except that the liquid 20 was a resin mixture (A) of the following composition:

0.2 percent gamma glycidoxypropyltrimethoxysilane coupling agent

0.5 percent ammonium hydroxide

8 percent acrylic resin Polycryl 7Fl-polymer

1 percent Emery fatty type softener (7777-softener )

2 percent epoxy resin (Moretex 7020 )

2 percent Ciba Blue BCT (Color Index No. 74160/74250)

b. Another piece of the same fabric was similarly treated using the following resin mixture (B) as the treating liquid:

0.2 percent glycidoxypropyltrimethoxysilane coupling agent

1 percent Emery fatty type softener

8 percent acrylic resin

2 percent epoxy resin

2 percent Reservol CT sol

2 percent Ciba Blue BCT (Color Index No. 74160/74250)

The epoxy, acrylic resin and softener used in Example 4 b were the same as those used in Example 4 a.

After passing through the padder rollers 22, the fabric in 4 a and 4b was oven dried for 3 minutes at 400.degree.F. The resulting products demonstrated significantly better penetration and appearance when compared with otherwise similarly processed products where the vacuum degassing step was omitted. Quantitatively, the vacuum degassing increased the resin pick up by 7.3 percent and 4 percent, by weight for resin mixtures (A) and (B), respectively.

Essentially similar advantages are shown when other types of fabric, e.g. a tight weave cotton, are resin treated as described in lieu of the fiberglass fabric used herein.

It will be appreciated that various modifications may be made in the invention as described above. For example, the padder rollers 22 may be replaced by a high expression pad to reduce the water or liquid content of the goods to the desired level, e.g. to about 50 percent after which the fabric is passed through another vacuum chamber (not shown) or perhaps back through the same vacuum chamber so as to complete the drying by vacuum.

While the vacuum or degassing treatment is shown at ambient temperature in the foregoing examples, even better results can be operated by heating the textile material while it is in the vacuum chamber, as noted above. Heating improves the efficiency of the degassing and the resulting textile has even greater imbibitive properties. Elevated temperatures of the order of, for example, 35.degree. - 100.degree.C., may advantageously be employed for the degassing operation.

Claims

Having described the invention, what we claim as new is:

1. In a process for impregnating a textile material in the form of a sheet or web having relatively fine openings therein, the improvement which comprises: subjecting the textile material to a relatively strong vacuum in a first chamber in order to degas the textile material; then passing the textile material from the first chamber into a second chamber containing a relatively low viscosity impregnating liquid whereby said textile material is thoroughly impregnated with said liquid; said textile material passing between said chambers while the two chambers are effectively maintained out of fluid communication with each other; and wherein textile piece goods are used as the textile material, such textile piece goods being of a fine weave, as could be used for suitings or shirtings, and comprising separate lengths or sections of material with joints or seams between adjacent sections joining a plurality of sections into a larger continuous length; and wherein the textile material is of indefinite length for continuous passage and movement serially through the first and second chambers; the first chamber having sealing means at the entrance and exit ends thereof for passage therethrough of the textile material without loss of the vacuum within said first chamber, and the sealing means at the exit end of the first chamber constituting the inlet into said second chamber, said latter sealing means also carrying, at least in part, the impregnating liquid so that, as the textile material passes therethrough, it passes directly and immediately into the impregnating liquid; and wherein the second chamber is rendered fluidtight and is placed under superatmospheric pressure so that the impregnating liquid therein is pressurized; and further wherein the textile material is not subjected to said impregnating liquid until after it passes through the first chamber.

2. The process defined in claim 1 wherein sealing means are provided at the exit end of the second chamber and further wherein the textile material is fed continuously through said inlet and exit ends of said second chamber and through the pressurized impregnating liquid therein without loss of vacuum in the first chamber and without loss of pressure in the second chamber.

3. The process defined in claim 2 wherein said second chamber also includes a treating gas therein and wherein the textile material is passed first through the impregnating liquid in the second chamber and then through the treating gas therein before exiting from that chamber.

4. The process defined in claim 3 wherein the treating gas is steam.