GB2034781A - Continuous compressive shrinking resin curing or heat setting method and apparatus - Google Patents

Abstract

A tubular knitted fabric 10 is treated with a stabilizing resin, the treated fabric is moistened, e.g. by a steam box 19, and then subjected to compressive shrinking, the compressively shrunk fabric is then heated in a first zone to drive off the moisture and is then heated in a second zone to cure said resin. The compressive shrinking may be effected by a device 23 comprising a flexible shoe 21, a blanket 22 and a heated drum 23a, the surface of the drum 23a forming the first heating zone. The second heating zone is formed by a curing oven 25. Alternatively, the process is applicable to heat setting and compressively shrinking a fabric. <IMAGE>

Description

SPECIFICATION Continuous compressive shrinking resin curing or heat setting method and apparatus BACKGROUND OF THE INVENTION The present invention concerns the compressive shrinking and resin curing or heat setting of fabrics, particularly knit fabrics.

Typically, such fabric treated with uncured resin.is moistened and compressively shrunk while moist and while the resin is in an uncured state.

Thereafter, the compressively shrunk fabric is sent through a Paimer, (drum type drier), which dries the fabric and cures the resin. Unfortunately, both drying and curing limit the speed at which the fabric can be processed. It is normal for such fabric to be processed at say 1 2 to 1 5 yards per minute.

Even at such relatively low speeds, the resin is not altogether cured, since curing cannot occur until the fabric is dry or very nearly dry. Also, when tubular knit fabric is processed, because only one side of the fabric comes into contact with the drier drum, the curing is non-uniform vis-a-vis each side or layer of the tube. Similar limitations apply to heat setting of fabrics.

One possible solution to the foregoing difficulties would be to add a second drier drum, thus minimizing one sidedness. However, this cannot be totally eliminated since, as mentioned, curing or heat setting begins only after the fabric is fully dried or very nearly dried and contact with the respective drums will vary once curing or heat setting has begun.

In accordance with the present invention, the functions of drying, curing, or heat setting are separated in order to enable compressive shrinking of fabric to occur at approximately twice the speed of the presently known process. Since normally, woven fabric is precured, (with respect to compressive shrinking), and knit fabric is normally post-cured, the present invention is preferably applicable to the compressive shrinking and resin or heat setting treatment, (for stabilization thereof), of knit fabric.

SUMMARY OF THE INVENTION According to the present invention, fabric, (preferably knit fabric), which has been treated with an uncured stabilizing resin is moistened and steamed preparatory to being compressively shrunk in the manner presently known. The fabric is compressively shrunk in a conventional rubber belt shrinking unit or by the use of a coated apron as shown in copending Ser. No. 810,854. Next the fabric is dried to remove all moisture. Although some resin curing may occur in the drier, this is not essential to the invention. The fabric is then passed in a relatively tensionless manner through a curing oven, preferably of the loop type with a dwell time therein of 30-90 seconds. Nonresinated heat settable fabric is similariy treated.

More specific aspects of the means to accomplish the foregoing will be found with reference to the specification.

BRIEF DESCRIPTION OF THE DRAWING Fig. 1. illustrates diagrammatically a partial side elevation of a section of one form of apparatus suitable for practicing the invention.

Fig. 2. is a continuation of Fig. 1.

DESCRIPTION OF PARTICULAR EMBODIMENT Referring to the drawing in detail, it will be seen that a continuous web 10 of an uncured resin treated tubular knit textile fabric is fed from a truck 11 to skying rolls 12, 13, and 14 around an idler roll 15 to a pair of feed rolls 17 and 18 thence through a steam box 1 9 wherein the web 10 has its moisture content adjusted by spraying with steam and/or water. The resin is of a type normally used to effect stabilization of the compressive shrinking process. Prior to being compressively shrunk the web 10 then passes through a spreader 20 to allow the fabric to relax before being fed between a flexible shoe 21 and the blanket 22 of the heated drum felt belt compressive shrinker 23. The arrangement being more particularly shown in patentees copending application Ser. No.810,854.It will be understood that a rubber belt compressive shrinking machine with or without a flexible shoe is considered an equivalent to the illustrated apparatus.

The fabric, when passing about heated drum 23a will, during its initial passage be fully dried.

Some curing of the resin may then occur but the function of this initial heating of the fabric is primarily to dry the fabric and not to cure the resin.

After the fabric 10 is fully dried complete curing of the stabilizing resin is effected by feeding the web 10 over conveyor belt 24 into a loop type low tension curing oven 25. The poles 26 therein are driven by a differential drive and the conveyor belt 24 is driven by a different differential drive so that varying the speeds of the two drives will result in variations of the loop lengths of the web 10 between poles 26 thereby increasing or decreasing the curing time of the fabric in the oven 25 and also providing high dwell time in the same volume. A most important aspect in feeding the fabric and in the use of the oven 25 is to provide relatively tension less handling of the fabric throughout the curing in order to prevent altering the shrinkage characteristics of the web 10 while the stabilizing effect of the resin is being achieved.

After curing the fabric is fed through a plaiter 26 which deposits or lays the web 10 in folds of preselected lengths on table 27.

Heretofore, in the standard, range, resin curing took place in the drier, more or less as part of the drying step. Effectively, the compressive shrinking apparatus had to be slowed to about 12 yards per minute to accommodate the necessary curing time; but even at this slow speed the resin was only partially cured or the fabric partially heat set.

With the addition of a loop type curing oven 25 in tandem with the compressive shrinking range 23, operating speeds of 25-50 yards per minute are possible and dwell times of 30 to 90 seconds in the curing oven 25 are possible while assuring a complete curing of the resin.

Claims (14)

1. The method of integrating compressive shrinking of a fabric and curing of a stabilizing resin with which said fabric has been treated comprising the steps of: applying a stabilizing resin to said fabric, moistening said fabric to prepare the fibers thereof for compressive shrinking, subjecting said fabric to compressive shrinking to a predetermined degree, subjecting said fabric in a first zone to heat primarily to drive off said moisture and subjecting the dried fabric in a second zone to heat to completely cure said resin.

2. The method according to claim 1 wherein said fabric is a knit fabric.

3. The method according to claim 2 wherein heat is applied in said first zone by a drier drum and partial curing of the resin is effected in said first zone.

4. The method according to claim 3 wherein said fabric is maintained substantially tensionless throughout said second zone.

5. The method according to claim 4 wherein said resin is cured completely by passing said fabric through a loop type curing oven.

6. The method according to claim 5 wherein the speed of the process of treatment is approximately 25-50 yards per minute.

7. The method of integrating compressive shrinking of a fabric and heat setting of a fabric comprising the steps of: conditioning a heat settable fabric, to prepare the fibers thereof for compressive shrinking, subjecting said fabric to compressive shrinking to a predetermined degree, subjecting said fabric in a first zone to heat primarily to drive off said moisture and subjecting the dried fabric in a second zone to heat to completely heat set said fabric.

8. The method according to claim 7 wherein said fabric is a knit fabric.

9. The method according to claim 8 wherein heat is applied in said first zone by a drier drum and partial heat setting of the fabric is effected in said first zone.

10. The method according to claim 9 wherein said fabric is maintained substantially tension less throughout said second.zone.

11. The method according to claim 10 wherein said fabric is heat set completely by passing said fabric through a loop type curing oven.

12. The method according to claim 11 wherein the speed of the process of treatment is approximately 25-50 yards per minute.

13. A method of integrating compressive shrinking of a fabric and curing of a stabilizing resin with which said fabric has been treated, being a method substantially as hereinbefore described and as illustrated in the accompanying drawing.

14. A fabric whenever treated by a method according to any one of claims 1 to 13.