US3447885A - Crease-proof woven and knitted fabrics - Google Patents

Description

United States Patent M model), 1,857,993; Oct. 31, 1962, D 40,175; Nov. 14, 1962, D 40,280

Int. Cl. D061) 7/00 US. Cl. 8-17 11 Claims ABSTRACT OF THE DISCLOSURE A process for finishing woven or knitted secondary cellulose acetate fabrics to impart wash and wear properties thereto comprising embossing said fabrics on at least one side at an elevated pressure and at a temperature of between about 80 and 150 C., washing, treating the embossed fabric with dry steam, coloring and steam fixing the embossed and steam treated fabric for between about 3 to minutes, 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. 274,329, filed Apr. 19, 1963, now abandoned.

The present invention relates to crease-resistant woven and knitted fabrics, which retain their shape after wearing and Washing and a method of producing such wash and wear fabrics. These woven and knitted fabrics consist mainly of filaments or threads of partially hydrolyzed, acetone-soluble or secondary cellulose acetate. The fabrics may also contain some amounts of metal threads or textiles other than secondary cellulose acetate, such as wool or nylon. Ready-made goods consisting of the fabrics of the invention are easily handled and have an appearance so satisfactory that they need not be ironed but may be re-used immediately after washing and drying.

Up to now woven and knitted fabrics of secondary cellulose acetate exhibiting the above-mentioned properties have not been available. Various finishing processes have been described for imparting wash and wear properties to fabrics of cellulose acetate threads or filaments. For this purpose resins have been used, but satisfactory results have not been obtained. A somewhat better effect has been attained for Woven fabrics when the fabric has been found 'by flotation, pre-embossed and finished without stretching. By the use of this method, however, it has still not been possible to obtain fabrics of secondary cellulose acetate which need not be ironed after washing.

One object of the invention is a process for preparing essentially crease-proof woven and knitted fabrics made essentially of secondary cellulose acetate which exhibit the properties above described. Further objects of the invention are apparent from the following detailed description.

The process of the invention comprises subjecting woven or knitted fabrics to a particular combination of steps. These steps, although they have been known individually, have not heretofore been applied under the conditions specified or in such a combination to woven or knitted fabrics of secondary cellulose acetate. It is most surprising that by this combination of steps and conditions such unique results may be obtained, i.e., fabrics are obtained having the above-mentioned excellent properties.

According to the novel process of the present invention Patented June 3, 1969 and with regard to the treatment of woven fabrics, the following sequence of steps and conditions are applied:

(a) The crude woven fabric is embossed on one or both sides to obtain preferably a finely grained appearance or pattern. The temperature is maintained between about and 150 C. and the pressure is elevated, e.g. about 8,000 kg. for a calendering machine having .a width of 150 cm.

(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 roughly 65 to C. and preferably at about 75 to 80 C. Depending on the size used (eg, glue or starch size) temperatures as low as 40 C. may be sufficient. The Water is separated from the fabrics, 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 subjected to .a dry steam treatment 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). 3'

(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.

It is essential that all of the above process steps be carried out with minimal stretching and tensile stress applied to the fabric in both length and width. The entire process is conducted under slack conditions which allow free shrinkage. It is further important that the fabric not be pressed (except, of course, or folded, but that it be flattened or spread out while being treated, since wrinkles or creases would otherwise be fixed in the treated fabric.

After these process steps have been carried out, the fabric, if desired, may be used for tailoring. It has been found that the retention of dimensions of the thus treated fabric is at least about :*:I%.

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, e.g., 7,000 kg. for a calendering machine having a width of 150 cm.

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 be tween and C. The elevated pressure utilized is somewhat dependent up 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 machines 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 preferred 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 linearly 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 for step (a) embossing) 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 sufiiciently 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 coarse as to leave a readily discernible 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 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 no stretching or 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 knitted fabrics one side is embossed while with woven fabrics both sides are embossed.

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 (b) 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 preceeds 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 percent during washing) and the shrinkage tends to minimize the effects of embossing in step (a). As such, with knitted fabrics step (b) is conducted before step (a). With woven fabrics step (b) may also be conducted before step (a) if desired, particularly where the woven fabric has a lower mechanical stability since after washing the threads are better able to stand the subsequent embossing step.

Step (c), as all other steps, is conducted under conditions where the fabric can freely shrink, i.e., no tensile stress is applied in any direction. As such, the step is conducted when the fabric is in a slack condition such as placing it over a frame or stenter. The fabric, under free shrink conditions is contacted with dry steam preferably at temperatures between 115 to 125 C. e.g., 120 C. The step is conducted for a short period of time preferably between 8 to 20 seconds, e.g., 12 seconds.

Step (d) is a conventional dyeing or printing step known per se in the art. Step (d) normally follows step (c) particularly where a pattern is to be imparted to the fabric. However, in the case of uniform dyeing or printings, step (d) may come before step (c) since shrinkage during step (c) will have no effect on the colored fabric. With patterened fabric the shrinkage may not be uniform and the pattern mayb'ecome distorted. When step (0) follows step (d), step (c) is actually combined with step (e) and the time of step (e) is extended by the time normally used for step -(c) Step (e) is conducted by contacting the fabric with dry steam (as dry as possible) for a period of about 3 to 5 mins. 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 increase worth mentioning 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 and 125 C. e.g., C. This step imparts the final dimensional stability to the fabric and improves the wash and wear properties. Step (e) may also be conducted with wet steam (temperatures of about 100 to 115 C.) provides the time of treatment is extended for a longer period of time (e.g., 5 to 8 minutes). However, in this case the fabric becomes wet during treatment and this practice is not preferred.

The temperatures above referred to are temperatures at which the fabric is treated during processing (e.g., 115 to C. in step (e) refers to steam temperature).

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

For the sake of a different appearance of the woven or knitted fabrics treated according to the invention, warp or weft threads may be used having an irregular titre. This may be illustrated by the following: The thread leaving the spinning nozzle has a constant thickness if the thread is subjected to a constant tension. in this manner the thread 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 threads exhibits a regular pattern. The fabrics used in the present process are made of threads which When woven or knitted do not lead to an undesired regular pattern of the fabric, but to a linen-like texture. Threads are used which have, e.g., an average titre of 4 denier and have their changes in titre arranged at irreggular intervals.

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 are not ob tained. For example tests wherein embossing was carried out at 30 C.; where the steam treatment was deleted; where some or all of the steps were conducted under substantial tensile; where embossing and/or final dry steam treatment were deleted, all other process steps being the same, establish inferior wash and wear properties resulting.

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

EXAMPLE 1 The woven fabric to be treated is in the condition of a basket (mat) weave. The warp threads are threads of secondary cellulose acetate of 75 denier with 50 individual fibrils. The weft threads are threads 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.

This woven fabric is treated in the following way:

First it is embossed to obtain a finely crystalline (grained) pattern while the temperature is maintained between 80 and 90 C. and the pressure at 6 tons (6,000 kg.) using a calendering machine having a width of 150 cm. Then the fabric is desized at a temperature of 75 to 80 C. The water is withdrawn by reducing the pressure below atmospheric, and the fabric is dried without stretching.

EXAMPLE 2 The woven fabric is in the condition of a serge weave. The warp threads consist of secondary cellulose acetate of 75 denier with 50 individual fibrils. The weft threads consist of secondary cellulose acetate of 150 denier with 32 individual fibrils having an irregular titre. The number of threads 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 embossing is carried out at a temperature of 130 to 150 C. and at a pressure of 6 tons (6,000 kg.) for the calendering machine having a width of 150 cm. The resulting fabric has excellent hand and crease-resistance and is especially desirable for tailored suits.

' EXAMPLE 3 The woven fabric is in the condition of a basket (mat) weave. The warp threads are threads of secondary cellulose acetate of 100 denier with 24 individual fibrils having an irregular titre. The weft threads are threads of secondary cellulose acetate of 150 denier with 32 individual fibrils having an irregular titre. The number of threads in the warp is 38/cm. and in the weft 28/cm. This woven fabric is treated as described in Example, 1, and the product has substantially the same excellent properties as the product of Example 1.

EXAMPLE 4 The Woven fabric is again in the condition of a basket (mat) weave. The warp threads consist of secondary cellulose acetate of 75 denier with 50 individual fibrils. The weft threads consist of secondary cellulose acetate of 150 denier with 75 individual fibrils. The number of threads in the warp is 73/cm. and in the weft 30/cm.

This woven fabric is treated by first embossing one side of the fabric at 90 C. and at a pressure of 6,000 kg. using a calenden'ng machine having a width of 15 cm., to obtain a finely grained pattern, followed by embossing the other side of the fabric at 130 C. and the same pressure, to obtain a somewhat coarse-grained pattern. The further proc ess steps are the same as in Example 1.

EXAMPLE 5 A knitted fabric is used in carrying out the following embodiment of the invention. It comes from the warploom and consists of threads of secondary cellulose ace tate, some of 60 denier with 18 individual fibrils and the rest of 75 denier with 24 individual fibrils. This knitted fabric is first cleaned for 30 minutes at a temperature of 40 C. in a bath which has been provided with 2 g./liter of a conventional synthetic detergent.

After rinsing, removal of the excess water and drying, and knitted fabric is embossed at a pressure of 7,000 kg. using a calender-ing machine having a width of 150 cm., and at a temperature of 130 C. to obtain a pattern of medium size granulation.

The knitted fabric is then printed, dried and steamtreated for 30 minutes at a pressure of 1 atmosphere. The fabric is then washed and dried at 120 C. on a stenter without stretching. After these steps have been carried out, it is fixed for 4 minutes by means of steam as dry as possible at a temperature of 120 C. (If desired, knitted fabrics may be conventionally brightened prior to or after the step of printing.)

EXAMPLE 6 The woven fabric to be treated is the same as in Example l. The fabric is embossed on both sides with a fine grain pattern at a temperature between 120 and 130 C. at a pressure of 9 tons on a 150 cm. working width embossing machine. After washing and desizing, the fabric is dry steam treated in a slack condition at 120 for 12 seconds. The fabric is printed in a conventional manner and this step is followed by dry steam treatment for 4 minutes at 120 C. The product shows excellent wash and wear properties and good dimensional stability.

EXAMPLE 7 Woven fabric as in Example 3 is treated by embossing on one side at an elevated pressure of 7 tons on a cm. working width embossing machine having a crystal crepe pattern. The temperature is to C. After washing, desizing and removing the water by vacuum, the fabric is placed on a stenter and, without stretching, is dry steam treated for 9 seconds at 115 C. The fabric is dyed, washed and dried in a conventional manner and then dry steam treated for 3 minutes at 115 C.

EXAMPLE 8 A knitted fabric of secondary cellulose acetate is cleaned by washing in a bath containing a synthetic detergent in a conventional manner. The fabric is then embossed on one side by an embossing machine having a 150 cm. working width at a pressure of 8 tons and a temperature of 120 to C. to give a fine grain pattern. The fabric is dry steam treated in a slack condition for 14 seconds at 120 C. Thereafter the fabric is printed, steamed, washed and dried in a conventional manner. It is then dry steam treated for 4 minutes at 120 C. The resulting fabric has excellent wash and wear properties.

EXAMPLE 9 The knitted fabric is treated as in Example 5 except that a 100 cm. working width machine is utilized at a pressure of 6 tons and a temperature of 120 C. The fabric is fixed as the final step for 3 minutes by dry steam treatment at a temperature of 125 C.

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 wrinkle-free 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 woven or knitted secondary cellulose acetate fabrics to impart to the fabric the ability to be reused after washing and drying without ironing, said process comprising embossing said fabrics in essentially a dry condition on at least one side at an elevated pressure and at an embossing temperature of between about 80 and C. to impart a pattern to the fabric whereby the threads are stabilized, washing and drying, treating the fabric in essentially a dry condition with dry steam, permanently coloring and drying the colored fab- 7 ric and steam fixing the fabric in an essentially dry condition for between 3 to minutes, all steps in said process being conducted under conditions wherein the fabric is not stretched.

2. 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 100 to 200 cm. and at a temperature of between about 120 to 130 C.

3. The process for finishing woven secondary cellulose acetate fabric according to claim 1 comprising:

(a) embosing said fabric with embossing rolls at an elevating 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 and 200 cm. and at a temperature of between about 120 and 130 C.,

(b) washing, desizing and drying,

(c) dry steam treating at temperature between 115 to 125 C. for from 8 to 20 seconds,

((1) coloring and (e) steam fixing with dry steam for a period of between about 3 to 5 minutes at a temperature between about IIS and 125 C., all steps in said process being conducted under conditions wherein the fabric is not stretched or subjected to tensile stress.

4. The process for finishing knitted secondary cellulose acetate according to claim 1 comprising:

(a) washing,

(b) embossing said fabric 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 7 to 11 tons at a working width of 100 and 200 cm. and at a temperature of between about 120 and 130 C.,

(c) dry steam treating at a temperature between 115 and 125 C. for from 8 to 20 seconds,

8 (d) coloring and (e) steam fixing with dry steam for a period of between about 3 to 5 minutes at a temperature between about and C., all steps in said process being conducted under conditions wherein the fabric is not stretched or subjected to tensile stress.

5. The process according to claim 1 wherein the fabric is knitted and the fabric is first washed and then subjected to embossing.

6. The process according to claim 2 wherein the dry steam treatment is conducted at a temperature of between about 115 and 125 C. for from about 8 to 20 seconds.

7. The process according to claim 6 wherein the steam fixing is conducted at a temperature of between 115 and 125 C.

8. The process according to claim 1 wherein the coloring step precedes the step'of treating with dry steam.

9. The secondary cellulose acetate fabric produced by the process of claim 1.

10. The secondary cellulose acetate fabric produced by the process of claim 3.

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

References Cited UNITED STATES PATENTS 2,440,209 4/1948 Redman 260- 3,166,824 l/l965 Fuhr 2876 3,081,513 3/1963 Marek et al 28-76 OTHER REFERENCES Mawaco Advertisement, May 9, 1950.

NORMAN G. TORCHIN, Primary Examiner.

I. E. CALLAGHAN, Assistant Examiner.

US. Cl. X.R.

UNITED STATES RATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,447 ,885 June 3 1969 Eugen Hasselkuss et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 3, "Khodiaceta" should read Rhodiaceta line 53, "found" should read bound Column 2, line 15, "fabrics" should read fabric line 55, "up" should read upon line 59, "machines" should read machine Column 3, line 57, "lower" should read low Column 4, line 18, "provides" should read provided Column 5, line 31, "Example," should read Example Column 7, line 13, "embosing" should read embossing line 14, "elevating" should read elevated line 17, "and", first occurrence, should read to line 37, "and", first occurrence, should read to Signed and sealed this 12th day of May 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer