US3447884A

US3447884A - Crease-proof woven and knitted fabrics

Info

Publication number: US3447884A
Application number: US549824A
Authority: US
Inventors: Eugen Hasselkuss; Emil Kimmig
Original assignee: Rhodiaceta AG
Current assignee: Deutsche Rhodiaceta AG; Rhodiaceta AG
Priority date: 1963-08-03
Filing date: 1966-05-13
Publication date: 1969-06-03
Anticipated expiration: 1986-06-03
Also published as: CH1012664A4; CH1770967A4; AT280930B; GB1074707A; BE651295A; DE1460546A1

Description

United States Patent 3,447 884 GREASE-PROOF W0"EN AND KNITTED FABRICS Eugen Hasselkuss and Emil Kimmig, Freiburg im Breisgau,

Germany, assignors to Deutsche Rhodiaceta AG, Freiburg, im Breisgau, Germany N0 Drawing. Continuation-impart of application Ser. No. 349,133, Mar. 3, 1964. This application May 13, 1966, Ser. No. 549,824 Claims priority, application Germany, Aug. 3, 1963, D 42,175; Aug. 13, 1963, D 42,231 Int. Cl. D06c 15/00 US. Cl. 8-17 15 Claims ABSTRACT OF THE DISCLOSURE A process for finishing secondary cellulose acetate woven and knitted fabrics to impart wash and wear properties thereto comprising embossing said fabric on at least one s1de at an elevated pressure and at a temperature of between about 80 to 150 C., washing, dry heating the embossed fabric at a temperature of between about 180 to 200 C. for from about 20 to 30 seconds, coloring, and steam fixing the embossed and dry heated fabric for from about 3 to minutes at a temperature of from about 115 to 125 C., all steps in said process being conducted under conditions wherein the fabric is not stretched.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 349,133, filed Mar. 3, 1964, now abandoned.

The present invention relates to crease-resistant woven and knitted fabrics, which retain their shape after wearing and washing. These woven and knitted fabrics consist mainly of filaments or threads made from secondary cellulose acetate. They may also contain some amounts of metal threads or textiles other than cellulose acetate, such as wool or nylon. Ready-made goods made of the fabrics of the invention are easily handled and have an appearance so satisfactory that they need no ironing and may be reused immediately after washing and drying.

Up to now, woven and knitted fabrics of secondary cellulose acetate showing the above mentioned properties have not been available. Various finishing processes have been described for rendering fabrics of cellulose acetate threads or filaments and spun yarn essentially creaseproof. For this purpose resins have been used, but satisfactory results have not been obtained. A somewhat better effect has been attained for woven fabrics in the manner wherein the fabric has been bound by flotation, preembossed and finished without stretching. By this method too, it has not been possible to obtain fabrics of secondary cellulose acetate which need not be ironed after washing.

The object of the present invention is essentially creaseproof woven and knitted fabrics made of secondary cellulose acetate showing the properties above described and methods of producing such fabrics. Further objects of the invention are apparent from the following detailed description.

It has been found that fabrics with a high degree of crease-proof and wash and wear properties can be obtained by using the following steps with regard to the treatment of woven fabrics:

(a) The crude woven fabric is embossed on one or both sides, preferably one, to obtain preferably a finely grained apearance or pattern. The temperature is maintained between about 80 and 150 C. and the pressure is elevated to from about 5 to 12 tons.

(b) The woven fabric is washed and desized by treatment with water, which may contain a small amount of synthetic detergent, at a moderately hot temperature of 3,447,884 Patented June 3, 1969 ice roughly 40 to 90 C. and preferably at about to C. Depending on the size used (e.g., glue or starch size) temperatures as low as 40 C. are sufficient. The water is separated from the fabric, preferably under subatmospheric pressure (vacuum) and not by pressing off, squeezing, or centrifuging. The material subsequently is dried, e.g., by hot air without stretching.

(c) The woven fabric is heated for about 20 to 30 seconds, preferably by hot air, under free shrink conditions by, for example, passing it over a stenter in slack condition (i.e., the web is fed faster than it is withdrawn) to a temperature of between about 180 to 190 C.

(d) The so-treated woven fabric is, in a conventional manner, dyed or printed and, if printed, normally steamed for stabilizing the color. It can then be washed and dried and finished with common finishing agents, and may then be re-dried with moderate steaming.

(e) The thus-treated woven fabric is fixed in the presence of steam for a period of about 3 to 5 minutes.

When knitted fabrics are to be treated according to the invention, steps (a) and (b) are reversed, i.e., step (b) is carried out before (a). The pressure during the embossing step may be somewhat lower.

Step (a) as outlined above is conducted on conventional embossing machines having a normal working width of between about to 200 cm. depending upon the width of the fabric treated. The broad temperature utilized is maintained between 80 and 150 C. and preferably between and C. The elevated pressure utilized is substantially dependent upon the working width of the particular embossing machine utilized and ranges broadly from between about 5 to 12 tons with the preferred range being between 7 and 11 tons. As the working width of the machine increases the elevated pressure also generally increases with the ranges being as follows: 100 cm. working width, 5 to 10 tons with 7 to 8 preferred; cm. working width, 6 to 11 tons with 8 to 9 prefered and 200 cm. working width, 7 to 12 tons with 9 to 10 preferred. As can be seen the elevated pressures which can be utilized increase linearally as the Working width increases. Generally, the elevated pressure utilized is somewhat higher with woven fabrics than with knitted.

The woven or knitted fabrics are embossed using standard embossing rolls. There is no industry standard by which such rolls are classified, the choice normally being made by visual inspection. The shape of the pattern on the embossing rolls is not critical and may be of any nature; geometric or non-geometric, square, triangular, irregular, etc. The pattern itself is preferably finely grained but there is no upper limit on the coarseness of the pattern except practical considerations. Preferably the pattern will be sufliciently fine such that after completion of all the process steps the pattern will be nearly unrecognizable on the finished fabric. Needless to say, if desired for special effects, the embossing pattern may be so course as to leave a readily discernable pattern on the finished fabric.

The minimum fineness of the embossing pattern should of course be more than totally smooth. Good results have been obtained with embossing patterns having from about 400 to 17 peaks per square centimeter. The effect of step (a) is essentially to increase the final wash and wear properties in the finished fabric and to impart dimensional stability (with respect to shrinkage) so as to minimize shrinkage in the subsequent process steps. The step appears to stabilize the thread and to impart a slight, superficial hardening or corification to the thread. At the temperature specified and with elevated pressure, the coarseness of the embossing pattern is at least sufficient to impart the dimensional stability above mentioned. This also insures the increase in final wash and wear properties.

In line with the essential requirement that minimal stretching and tensile stress is applied to the fabric during the process steps it goes without saying that the embossing rolls turn at the same speed to avoid any stretch in the fabric. The fabric may be embossed on one or both sides (i.e., one or both rollers may be engraved or patterned) and preferably in the case of woven fabrics one side is embossed while with knitted fabrics it is possible to emboss on one, two or even on neither side.

When utilizing a fine embossing pattern, the upper embossing roll is normally heated and patterned while the lower roll is an unheated, unpatterned roll of, for example, rubber or cotton. Thus only one side of the fabric is embossed during a single pass through the rolls. With coarse patterns, the lower roll usually bears a pattern corresponding with the upper roll (though still unheated) and the fabric is embossed on both sides in a single pass through the rolls.

Step (1)) above is essentially a conventional washing and, where necessary, desizing operation (knitted fabrics are normally not sized). The washing is designed to remove impurities remaining from the weaving or knitting operation. The use of vacuum to remove the water insures no stretching of the fabric. When operating with woven fabrics, step (a) normally precedes step (b) while with knitted fabrics generally the opposite is true. The reason for this is that knitted fabrics tend to shrink more than woven fabrics (up to 10 percent during washing) and the shrinkage tends to minimize the effects of embossing in step (a). As such, with knitted fabrics step (b) may also be conducted before step (a) if desired, particularly where the woven fabric has a low mechanical stability since after washing the threads are better able to stand the subsequent embossing step.

While the general temperature range of step (c) is between about 180 C. and 190 C., a slight exceeding of this temperature is not detrimental. Generally the tempera? ture may range from 180 to 200 C. This thermal fixing of the woven or knitted fabrics is carried out in general by dry-heating the woven or knitted fabric being under slack condition. For example, the fabrics may be fed to a stenter (frame) in such a way that they do not undergo stretching even after fixing. This feeding under slack condition must be applied in both the longitudinal as well as the transverse direction of the woven or knitted fabric.

The treatment of cellulose acetate at the high temperatures of about 180 to about 190 C. or 200 C. has not been carried out up to now, as detrimental effects upon the cellulose acetate substances have been expected. It is thu most surprising, that with such high temperatures the described advantageous properties of the woven and knitted fabrics of celluose acetate may be attained while avoiding any detrimental effects.

Step (d) is a conventional dyeing or printing step known per se in the art. Step ((1) normally follows step (c) particularly where a dyed or printed pattern is to be imparted to the fabric. Furthermore since step involves high temperatures, the dyestuffs may not be resistant to such high heat and may be adversely effected. However, in the case of uniform dyeings or printings and where heat stable dyestuffs are used, step (d) may come before step (0) since shrinkage during step (c) will have no effect on the colored fabric and the dyestuff will resist the high heat. With patterned fabric the shrinkage may not be uniform and the pattern may become distorted.

Step (e) is conducted by contacting the fabric with steam as dry as possible for a period of about 3 to 5 minutes. If the fabric is treated for less than 3 minutes, some effect will be obtained but at less than 1.5 minutes there is no worthwhile increase in the wash and wear properties of the finished fabric. If the dry steam contact is longer than 5 minutes the effect is obtained but the longer steaming does not improve the effect and hence becomes uneconomical. The temperature of the steam during treatment is between about 115 and 125 C., e.g., 120 C. This step imparts the final dimensional stability to the fabric and improves the wash and wear properties.

The temperatures above referred to are temperatures at which the fabric is treated during processing (e.g. to C. in step (e) refer to steam temperature).

The new process gives to woven and knitted fabrics a smoother and more pleasant touch then with the process of copending concurrently filed patent application Ser. No. 549,826 (a continuation-in-part of US. Ser. No. 274,329). This new process gives a further advantage as in the case of knitted fabrics the embossing can be omitted entirely without greatly affecting the final result of the process. This improved process is of special advantage in the case of knitted fabrics as embossing sometimes is connected with difficulties, e.g., by rolling of the edges of the knitted fabrics, thus causing conveying difiiculties in the finishing treatment. Normally, with woven fabrics, embossing on only one side is preferred. Where the woven fabric is heavy and thick embossing on both sides is of advantage. Twill fabrics, e.g., and fabrics with knop yarns may be embossed only on the back side at an approximate temperature of 90 C. to 100 C. in order to maintain their pattern. Similarly, woven fabrics with tabby (calico) weave may be handled.

Tests have shown that if the above conditions are not maintained during the process steps, the improved wash and wear properties of the present invention will not be obtained. For example, tests wherein the embossing was carried out at 30 C.; where the hot air treatment was deleted; where all or some of the steps were conducted under substantial tensile stress and where embossing and/or the final dry steam treatment were deleted, all other process steps being the same, establish inferior wash and wear properties resulting.

Except for this basic deviation, i.e., brief termal fixing at high temperature in place of the dry steam treatment taught in the copending application and the possibility of omitting the embossing step completely, if desired, with knitted fabrics and with woven fabrics preferably embossing on one side only, the new process uses the same process steps described in said patent application.

As in the case of the process of said patent application it is important that all the process steps are carried out without minimal stetching of the fabric in either length or width and with the application or minimal tensile stress to the fabric in any direction. It is further important that the fabric not be pressed (except of course during the embossing step) and folded, but rather be flattened or spread out while being treated, since wrinkles or creases would otherwise be fixed in the treated fabric. The entire process is conducted under slack conditions which allow free shrinkage.

After these process steps have been carried out, the fabric is ready for tailoring. It has been found that the retention of dimensions of the thus treated fabric is at least about i1%.

The properties of the thus treated woven or knitted fabrics are particularly favorable if these consist of filaments with fibrils of low count gauge, e.g., filaments of 75 denier with 50 fibrils or denier with 100 fibrils, and if their weave is loose, e.g., a flotation weave.

For the sake of a different appearance of the woven or knitted fabrics treated according to the invention, warp and/or weft filaments may be used having an irregular titre. This is illustrated by the following:

The filament leaving the spinning nozzle has a constant thickness if the filament is subjected to a constant tension. In this manner the filament is regularly reduced in thickness with regard to the diameter of the spinning nozzle. If the tension is periodically relaxed and increased, the fabric obtained from such filaments shows a regular pattern. The fabrics used in the present process are made of filaments which when woven or knitted do not lead to an undesired regular pattern of the fabric, but to a linen like texture. Fabrils are used which have, e. g., an average titre of 4 denier and have their changes in titre arranged at irregular intervals.

Beside the use of filaments with an irregular titre, the pattern of the woven fabric may be advantageously infiuenced by using woven fabrics with a dense set and bound alternately by flotation and shortly tied filaments as, e.g., in the case of a twill weave.

By secondary acetate is obviously meant the partially hydrolyzed full acetate which is acetone-soluble as opposed to the full acetate normally referred to as triacetate.

The following examples are not to be understood as a limitation of the invention but only as an illustration.

EXAMPLE 1 A woven fabric is treated. The warp filaments are filaments of secondary cellulose acetate 75 denier with 50 individual fibrils and 190 turns per meter. The weft filaments are filaments of secondary cellulose acetate of 150 denier with 75 individual fibrils and 80 turns per meter. The woven fabric is in the condition of a tabby weave, with very close set, i.e., 73 filaments per cm. in the warp and 30 filaments per cm. in the weft. The woven fabric is embossed on one side at 120 C. and at a pressure of 9 tons on a 150 cm. working width machine with a fine crystal like pattern. Then, the woven fabric is wetted and desized in book form up to a temperature of 75 to 80 C. using a bath containing soap and ammonia. Thereafter, the liquid is drawn off by vacuum and the fabric dried on a short-loop-drier. The woven fabric is put without additional stretching on a pinstenter and fixed at a temperature of 185 to 190 C. for 25 to 30 seconds under slack condition. The fabric is then printed with dispersed dyestuffs, steamed in a star streamer, carefully rinsed in conventional manner and dried on a short-loop-drier. Subsequently, the fabric is subjected to fixing with steam as dry as possible for 4 minutes at 120 C. in a finish decatizing machine. Thereafter the fixed fabric is dried and passed without additional stretching through a breaking machine for modifying the touch of the woven fabric.

The same treatment may be applied to plain woven fabrics.

The woven fabric thus treated shows excellent wash and wear properties and a touch like natural silk.

EXAMPLE 2 The woven fabric shows a serge-weave. The filaments used for warp are of secondary cellulose acetate 75 denier with 50 fibrils. The filaments used for weft are of secondary cellulose acetate 150 denier with 32fibrils. The number of filaments in the warp is 72/cm. and in the weft 30/cm.

This woven fabric is treated as described in Example 1 with the exception that the embossing is carried out with a medium crystal pattern at a temperature of 130 C. and a pressure of 7 tons for a calendering machine with a width of 100 cm. The obtained woven fabric has excellent touch and gives crease resistance and is especially suited for tailored dresses.

EXAMPLE 3 Woven fabric is used wherein the warp threads are of secondary cellulose acetate of 75 denier with 50 individual fibrils. The weft threads are also of secondary cellulose acetate of 150 denier with 100 individual fibrils. The number of threads in the warp is 73/cm. and in the weft 30/cm.

The fabric is treated by embossing a finely crystalline pattern on one side with a 200 cm. working width at 10 tons pressure and 125 C. temperature. The so embossed fabric is Washed and desized in the usual manner and then contacted under slack conditions with hot air at 190 to 195 C. for 20 seconds. The fabric is then dyed with conventional dyestuffs being careful not to stretch or crease during the dyeing operation. After the dyeing, the fabric is rinsed and dried. The fabric is then contacted with dry steam at C. for 3 minutes while in a slack condition.

The appearance and properties of the thus treated fabric, particularly its crease resistance, are excellent.

EXAMPLE 4 Woven fabric is used having Warp threads of 100 denier with 24 individual fibrils having irregular titre and weft threads of 150 denier with 32 individual fibrils of an irregular titre. The number of warp threads is 38/cm. and weft 28/ cm. The fabric is treated as in Example 3 except that embossing is conducted on a 150 cm. working width machine at C. and an elevated pressure of 8 tons and the hot air treatment is at 180 C. for 25 seconds. The resulting fabric shows excellent wash and wear properties.

EXAMPLE 5 The web is a knitted fabric (material derived from a warp loom in the sequence of L 1-0-4-5, L 1-001) which consists of yarns of secondary cellulose acetate. It is washed for 30 minutes at a temperature of 40 C. on a winch vat with a synthetic detergent (2 g./l. of water) for the sake of preliminary cleaning. Thereafter, the web is carefully rinsed, the liquid drawn otf and the knitted fabric then dried on a frame under slack condition and by setting the width given by the frame measurements. The washed fabric is then embossed on one side with a fine grain pattern at a pressure of 9 tons in a cm. working width machine at 120 C. The embossed knitted fabric is then fixed on the pinstenter under free shrink conditions at a temperature of to C. for 25 to 30 seconds. The fabric is then printed with dispersed dyestuffs by screen printing process, thereafter dried, steamed by star steamer during 30 minutes at 1 at pressure, carefully rinsed, moderately soaped, again rinsed, liquid drawn off and dried. The knitted web is then brightened (revived) with washfast products and then dried on a frame under slack condition and by setting the given width. Finally, the knitted web is fixed for 4 minutes with steam as dry as possible at 120 C. in a finish decatizing machine.

The same treatment may be applied to plain knitted fabrics. The fabric has excellent wash and wear properties.

EXAMPLE 6 The web is a knitted fabric which consists of yarns of secondary cellulose acetate. This knitted fabric is treated as described in Example 5 with the exception that after a preliminary cleaning, a one side embossing is carried out at a temperature of 130 C. and a pressure of 8 tons for a calendering machine with a width of 150 cm. The hot air treatment is conducted at a temperature of 185-190 C. for a period of 25 seconds. The obtained knitted fabric has excellent touch and very good crease resistance.

EXAMPLE 7 The fabric of Example 5 is processed in the same manner as Example 5 except that the knitted fabric is not embossed. The obtained fabric receives excellent touch and crease resistance properties.

EXAMPLE 8 Woven twill fabric was embossed on one side with a medium crystal pattern at a pressure of 7 tons, a temperature of 120 to 125 C. on a 100 cm. working width machine. The embossed fabric was desized at a temperature of 80 C., rinsed, the water removed by vacuum and dried at a temperature of 90 C.

The fabric was treated at 185 C. with hot air for 20 seconds in a slack condition. The fabric was then dyed and finally treated with dry steam for 4 minutes at 125 C.

It is understood that the above described illustrations and embodiments are set forth for the purpose of describingthis invention and are not intended to limit its scope which is determined by the appended claims.

The wash and wear fabric produced according to the present invention is unique and has properties unobtainable by other known processes. The dimensional stability and wrinklefree characteristics are superior. While the exact nature of the physical changes in the fabric are not clear it has been established that certain physical characteristics are changed by the process according to the invention.

For example, when filaments of the same titre and length are compared, each of the same secondary cellulose acetate, one treated according to the present invention and one not, the differences in solubility are readily apparent.

' For example, a comparison of solubility in freshly distilled cinnamic aldehyde at 55 C. shows that filaments treated by the present invention require over two times as long to dissolve and in many cases well over three times as long. Furthermore, when comparing the swelling values of treated and untreated secondary cellulose acetate fibers, it is seen that the swelling capacity of the treated fibers is reduced by about 30 percent as compared with the untreated fabric.

It is therefore clear that the process of the present invention produces certain physical changes in the fabric which seem to account for the superior wash and wear properties obtained by the present invention.

What we claim is:

1. A process for finishing secondary cellulose acetate woven fabrics to impart to the fabric the ability to be reused after washing and drying without ironing, said process comprising:

(a) embossing the fabric in esesentially a dry condition on at least one side at an elevated pressure and at a temperature of from about 80 to 150 C. to impart a pattern to the fabric whereby the thread is setabilized,

(b) washing and drying,

() dry heating the embossed fabric is essentially a dry condition at a temperature of between about 180 to 200 C. for from about 20 to 30 seconds,

(d) coloring and drying the colored fabric,

(e) steam fixing the embossed and dry heated fabric in essentially a dry condition for from about 3 to 5 minutes at a temperautre of from about 115 to 125 C., all steps in said process being under conditions wherein the fabric is not stretched.

2. A process for finishing secondary cellulose acetate knitted fabrics to impart to the fabric the ability to be reused after washing and drying without ironing, said process comprising:

(a) washing and drying,

(b) dry heating the fabric in an essentially dry condition at a temperautre of between about 180 to 200 C. for from about 20 to 30 seconds,

(0) coloring and drying the colored fabric,

(d) steam fixing the dry heated fabric in essentially a dry condition for from about 3 to 5 minutes at a temperature from about 115 to 125 C., all steps in said process being conducted under conditions wherein the fabric is not stretched.

3. A process according to claim 2 wherein the fabric is embossed on at least one side at an elevated pressure and at a temperature of from about 80 to 150 C. to impart a pattern to the fabric whereby the thread is stabilized prior to dry heating.

4. A process according to claim 1 wherein the fabric is embossed with embossing rolls at an elevated pressure which linearly increases with an increase in the working width of the embossing rolls and is equivalent to about 5 to 12 tons at a working width of to 200 cm.

5. A process according to claim 3 wherein the fabric is embossed with embossing rolls at an elevated pressure which linearly increases with an increase in the working width of the embossing rolls and is equivalent to about 5 to 12 tons at a working width of 100 to 200 cm.

6. The process according to claim 1 comprising the steps of (a) embossing said fabric with embossing rolls on at least one side at an elevated pressure which linearly increases with an increase in the working width of the embossing rolls and is equivalent to about 7 to 11 tons at a working width of 100 to 200 cm. and a temperautre of from about to 130 C.,

(b) washing, desizing and drying,

(c) dry heating at a temperautre of between about 180 to 190 C. for from about 20 to 30 seconds,

(d) coloring the fabric, and

(e) steam fixing for from about 3 to 5 minutes at a temperautre of between about 115 and C.

7. The process according to claim 1 wherein prior to step (a) the fabric is embossed with embossing rolls on at least one side at an elevated pressure which linearly increases with an increase in the working width of the embossing rolls and is equivalent to about 7 to 11 tons at a Working width of 100 to 200 cm. and at a temperautre of from about 120 to C.

8. The process according to claim 1 wherein the fabric after washing and drying, is colored and dried prior to dry heating.

9. The process according to claim 1 wherein embossing is conducted at a temperature of between 120 and 130 C.

10. The process according to claim 3 wherein the embossing is conducted at a emperature of between about 120 to 130 C.

11. The process according to claim 1 wherein the dry heating of the embossed fabric is conducted at a temperature of between to C.

12. The process according to claim 2 wherein the dry heating of the embossed fabric is conducted at a temperature of between 180 to 190 C.

13. The process according to claim 2 comprising:

(a) washing,

(b) dry heating at a tempearutre of between about 180 to 190 C. for from about 20 to 30 seconds,

(c) coloring the fabric, and

(d) steam fixing for from about 3 to 5 minutes at a temperature of between about 115 to 125 C.

14. The secondary cellulose acetate fabric produced by the process of claim 4.

15. The secondary cellulose acetate fabric produced by the process of claim 2.

References Cited UNITED STATES PATENTS 4/1948 Redman 26-l8.5 2/ 1967 Davis et al. 28-76 po-mso Patent No.

Dated June 3, 1969 lnv Eugen Hasselkuss et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line Column 2, line Column 2, line Column line Column line Column 5, line Column 7, line Column 7, line Column 7, line Column 7, line Column 7, line Column 8, line Column 8, line Column 8, line Column 8, line Column 8, line (SEAL) Attest:

Edward M. Fletcher, Ir. Attasting Officer change "prefered" to preferred change "corification" to cornification change "celluose" to cellulose change "etetching" to stretching change Fabrils" to Fibrils change "streamer" to steamer change "esesentiall to essentially change "setabilized to stabilized change "is" to in change "temperautre" to temperature after "temperature" insert of change "temperautre" to temperature change "temperautre" to temperature change "temperautre" to temperature change "temperautre" to temperature change "tempearutre" to temperature SIGNED 'A'ND SEALED MAY 5 WIILIAM E. 80m, JR- Gonmissionar 0! Rants