WO2006106533A1

WO2006106533A1 - Dye-works control method in the manufacturing of denim-type fabric

Info

Publication number: WO2006106533A1
Application number: PCT/IT2005/000180
Authority: WO
Inventors: Andrea Busolo
Original assignee: Montebello S.R.L.
Priority date: 2005-04-04
Filing date: 2005-04-04
Publication date: 2006-10-12
Also published as: BRPI0520219A2; MX2007010686A; EP1866473A1

Abstract

A dye-works control method in the manufacturing of Denim-type fabric comprises the steps of: inserting a sample thread (13) along with a carpet of manufacturing threads (14); subjecting the sample thread (13) and the carpet of threads (14) to the same dyeing process; gathering the sample thread (13) at the end of the dyeing process; preparing a fabric support entirely made of the sample thread (13); correlating portions of fabric support to respective manufacturing instants; controlling the deviances of the shade of the end Denim fabric, by means of the changes of shade of the fabric portion.

Description

DYE-WORKS CONTROL METHOD IN THE MANUFACTURING OF DENIM- TYPE FABRIC

DESCRIPTION The present invention refers to a dye-works control method in the manufacturing of Denim-type fabric.

In the field of textile industry it is well-known to all the fabric known under the name of "Denim", characterized in that the warp threads, used for confectioning Jeans articles of clothing, are dyed with a specific method and dye prior to the weaving phase. These peculiarities give to the Denim fabric unique features that are enhanced by the subsequent treatments to which it is subjected. In fact, the aspect of the fabric customarily seen in articles of clothing on display in shops is not the one being sold to the confectioner. The latter, upon having prepared the articles, entrusts them to specialized laundries that wash, rub and deteriorate the fabric and the dye, attaining a look unique and inimitable with other textile bases.

Basically, the manufacturing procedure starts from the raw cotton in bales, feeding the cards. The latter are machines having a series of steel hooks, mounted on a large drum and on rollers, which straighten out and unfold the fibre tufts forming the roving ready for spinning. Uninterruptedly, the roving passes through the drawing frames and, finally, the open-end spinning machines . Once produced, the yarn reels go to feed the warping department, which will produce the sectional beams to be dyed in dye-works. More precisely, with the warping operation the so-called warp threads are made, i.e. that set of threads, longitudinally stretched onto a loom, intended to cross with the weft to form the fabric. The warp threads are wound, arranged on parallel lines in high number, on cylindrical drums that are denominated sectional beams.

The peculiarity of the Denim lies in dyeing only the warp threads prior to the weaving, so that by the subsequent loom crossing with the weft the Denim fabric, and therefrom the famous Jeans, be obtained. In fact, Denim weft is formed by undyed raw threads, allowing, interlaced with dyed warp threads, to attain the peculiar color effect that makes Denim so distinctive.

The sectional beams obtained in the warping phase, brought together in sets of 8-12, feed the dyeing lines, through which the yarn is dyed in the desired coloration. The dye-works fundamentally works with Indigo-based preparations. Indigo is generally applied to the cotton thread with the specific and characteristic sequential impregnation-squeezing technology. This technology, along with the peculiar features of the indigo dye, scanty fastness to rubbing and washing, allow a superficial dyeing of the thread, which only thus can generate fadings characteristic of the denim when it is subsequently treated (e.g., with a stone washing it exhibits a pepper-and-salt look inimitable on other textile bases) . Evidently, the problems to be found in dye-works are related to undesired changes of color caused by problems of various nature that may occur during the dyeing of a manufacturing.

These problems can, e.g., comprise atmospheric or raw material changes, mechanical problems or problems related to the specificity of the manufacturing, like the slowing down or the stopping of the line, for yarn breakages or other factors compelling to slow down or stop the line. The time interval in which the thread remains in contact with the baths is proportional to the dyeing rate. Therefore, evidently the absorption of the dye is proportional to the contact time, and the changes of line speed constitute a considerable problem of the dye-works .

At the end of the cycle, color measuring is purely indicative, as the operator in charge of control detects merely one of the dyeing aspects, i.e., the conformity of the dye to the sample and the preceding production.

However, the fastness of the color to the subsequent treatments is not measurable; therefore, in this phase its conformity cannot be effectively assessed.

Accordingly, the actual control can be performed only at the end of the cycle, by washing the fabric to imitate the client's treatments. However, at the end of the cycle the dyeing result is influenced also by the pattern of the fabric and by the finishing to which the latter is subjected, rendering problematic an assessing of the dye-works performances.

A viable solution consists in using complex instruments of chromatic analysis, already used in other phases of the manufacturing. However, such instruments, in view of their complexity and therefore of their cost, can be used merely to carry out sample tests for statistical ends and anyhow do not allow to assess the behavior of the color to the subsequent treatments. Moreover, said instruments are unsuitable for a continuous control, required for the abovedisclosed dye- works problems, if not at extremely high costs.

The main drawback of the end-of-cycle control lies in that the weaving requires rather long times; thus, dyeing problems cannot be singled out over times sufficiently short to readily intervene on the cycle under way.

A further drawback lies in that, even though shade is mainly linked to the dyeing operations, also the other phases of the manufacturing have an effect on the final shade of the product; thus, without an adequate control during the dyeing itself it is not possible to understand whether any problems are due to the dyeing phase or to issues of other nature, leading however to deviations in the final shade with respect to the one foreseen.

Hence, the technical problem underlying the present invention consists in providing a method for controlling the dyeing shade of Denim thread overcoming the drawbacks mentioned with reference to the known art.

Such a problem is solved by a dye-works control method prior to the manufacturing of Denim-type fabric as defined in the appended claim 1.

The control method according to the invention allows an effective control of the shade of the thread, and therefore of the fabric, in extremely short times, without waiting for the manufacturing of the end product.

Such a control does not require the complex instrumentations mentioned above.

Moreover, the problems influencing the shade of the finished fabric due to the dyeing phase may be differentiated from those linked to the subsequent manufacturing .

Other advantages, features and the modes of employ of the present invention will be made apparent in the following detailed description of some embodiments thereof, given by way of example and without limitative purposes. Reference will be made to the figures of the annexed drawings, wherein: figure 1 is a schematic illustration showing a dye- works for Denim fabric; figure 2 is a perspective view of sectional beams, detail of the dye-works for Denim fabric of figure 1; figure 3 is a perspective view illustrating a feeding section 1, in which there are loaded the sectional beams of figure 2, and the inlet of a dyeing section of the dye-works according to the present invention; figure 4 is a perspective illustration of a carpet of manufacturing threads and of a sample thread, inserted at the inlet of the dyeing section of figure 3; figure 5 is a perspective view showing a vat of the dyeing section of figure 3; figure 6 is a perspective view illustrating an outlet section in which the carpet of threads is gathered in a single beam.

With initial reference to figure 1, a dye-works for Denim fabric comprises a feeding section 1, in which a plurality of sectional beams 11 are loaded, a dyeing section 2, comprising a series of vats 21, downstream of each one thereof there being arranged a pair of rollers 22, an outlet section 3 and a gathering section 4, in which the threads coming from the sectional beams are, upon having completed the dyeing, gathered in a single beam 41.

The dyeing procedure essentially takes place according to a technique conventional for Denim. In particular, with reference to figures 1 to 3, the sectional beams 11, obtained in the warping phase, brought together in eight or twelve groups, feed the dyeing section 2, gathering the threads in a single carpet of threads 14. In the dyeing section 2 the yarn, formed by the carpet of threads 14, is dyed in the desired coloration. The dye-works fundamentally works with indigo-based preparations. Indigo is applied to the cotton thread with the impregnation-squeezing technology.

In other words, the carpet of threads 14 coming from the sectional beams 11 is passed in a series of vats 21 containing the dye bath. Between one vat and another one, the carpet of threads passes through a pair of squeezing rollers 22 eliminating the excess of liquid. Subsequently, the dye absorbed by the thread is oxidized in air, by natural or forced convection. Thus, the carpet of threads 14 can pass into the subsequent vat to repeat this operation. The latter can be repeated from six to ten times, depending on the line, prior to being washed and fixated with the same methodology.

The method according to the present invention provides, unlike the commonly used procedure, the inserting of a sample thread 13, along with the carpet of manufacturing threads 14 coming from the sectional beams 11 .

Incidentally, the Applicant experimented that the sample thread 13 may conveniently be of non-shot type, of twisted pure cotton, with Ne equal to 30/2. These features make the thread more resistant to breakage, without overly prejudicing its workability.

With reference to figure 4, the inserting of the sample thread 13 in the dyeing line is suitably carried out just downstream of the inlet section of the dye- works, upstream of the first vat of the dyeing section 2.

Moreover, it is appropriate that the sample thread

13 be inserted at a sufficient distance from the selvedge of the carpet of threads 14, so as not to be excessively near to the manufacturing ends, hence preventing the associating to the sample thread, in the way described hereinafter, of a portion of the carpet of threads not characterizing the manufactured end fabric.

As an indication, optimum results were attained by positioning the sample thread 13 at a distance ranging from 15 to 25 cm from the selvedge, which generally has a width not greater than 5 cm.

The sample thread, thus inserted, follows the carpet of warp threads 14 in the dyeing section, it being subjected to the same process of the others and therefore keeping all the changes of shade and the problems of various nature influencing the qualitative result of the end product .

It is important to note that, were it to be taken as sample thread merely a thread coming from the sectional beams 11, the gathering beam 41 would have an unevenness in the carpet of dyed warp threads entailing remarkable difficulties in the subsequent weaving phase. Moreover, as specified above, the sample thread 13 is suitably selected of a particular type and it undergoes some preparatory operations, prior to the dyeing phase, in order to facilitate the manufacturing thereof; operations that could not be viable when taking the thread from the carpet 14 .

The sample thread comes from a single lot expressly set apart therefor, in order to rule out raw material problems . Then, the sample thread 13 is gathered at the end of the dyeing process, at the outlet section 3, upstream of the gathering section.

In particular, with reference to figure 6, it is suitably used a reel winder 6 connected, e.g., electrically, to the remainder of the dyeing section. In fact, since the control should take place continuously, in case the reel winder detects an interruption in the gathering of the sample thread, e.g., due to a breakage of the thread itself, the entire dye-works is automatically stopped, allowing to repair the sample thread.

The reel winder works at the same dyeing rate, to allow perfect synchronism between the gathering of the outlet beam and of the sample thread onto the reel winder.

The length of the hank of sample thread to be inserted is suitably equal to the length of the entire manufacturing lot, so that the dyeing phase of the latter be completely described by a single thread reel. Anyhow, the manufacturing lot may also be described by plural reels of sample thread, provided that to each reel there be clearly and univocally associated a portion of the manufacturing lot.

However, evidently during the manufacturing of a single lot different beams are used, each one possibly having different features of shade, due to the variability of the several parameters coming into play in the dyeing^' phase, or for any influence of the spinning process . Therefore, it is advisable to leave a trace of the beam change operations onto the sample thread reel. For this purpose, at each beam change the sample thread is decolorized at the first outlet section of the dyeing section. To decolorize the thread there may be used a mere brushing of hypochlorite, which is capable of thoroughly eliminating the dye laid by means of the preceding passages into the vats.

Since Denim warp fabric is commonly characterized, after the dyeing phase, by a rather dark blue shade, the decolorized zone will be quite evident, enabling to univocally identify the beam changes in the sample thread.

Besides from beam changes, interruptions to the dyeing process can also occur for several other reasons, in particular when the sample thread breaks. As mentioned hereto, in case of such an occurrence taking place the dye-works is automatically stopped, it being connected to the reel winder, and thereby the two ends of the sample thread can be reunited therebetween. Also in this phase it may be advisable to mark, always by decolorization, the taking place of such an occurrence. Moreover, the operation of the dye-works is registered depending on the gathering of the sample thread onto the reel winder, so as to create an univocal correspondence between thread length and manufacturing instant. In practice, thus to each thread portion there could be associated a corresponding warp portion, coming from a definite instant of the manufacturing.

The method according to the present invention provides to use the sample thread to assess the shade obtained with the dyeing phase. Such a peculiarity entails a relevant advantage, as the warp threads do not give the option of assessing the shade obtained during the dyeing if not after the weaving phase and the subsequent finishing, whereas the sample thread 14 could give near-immediate indications on the dyeing pattern, when subjected to the remarkably quick operations described hereinafter. In fact, the method provides, following the gathering into the reel of the reel winder 6, the preparing of a support entirely made of the sample thread 14. In particular, such a support can be made starting from the reel of sample thread obtained in the dyeing phase, with a knitting machine, making the support in the form of a single continuous sock.

The use of the fabric in form of sock proves particularly suitable to the subsequent manufacturing, in particular to the washing phase to which the support is suitably subjected.

Therefore, the subsequent step is that of knitting the thread until obtaining a single sock corresponding to the manufacturing of the entire lot, or of the lot portion that the sample thread reel describes.

In the sock there will be evident the portions in which the thread has been decolorized, so as to facilitate the identifying therein of the beam changes, or optionally of the manufacturing downtimes.

It is important to specify that the knitting operation is extremely quick when compared to the operations that instead the warp yarn has to undergo after the dyeing phase. Moreover, instead of being knitted in the form of a sock, the sample thread may be manufactured in any other equivalent way, as long as there are obtained fabric portions associable to the dyeing process of the warp threads . In order to facilitate and speed up the knitting operations of the sample thread, the latter is suitably waxed. This operation is carried out by means of a reel rewinder, winding the thread on a new reel and passing it below a wax pellet. Thus, the sample thread becomes less rigid, more workable; lastly, during the knitting it produces much less dust, which has negative effects on the movable trolleys and the needles and needle holders of the knitting machine.

Upon producing a single sock from a reel of suitably waxed sample thread, the former entirely represents the manufacturing. In principle, in it there can be singled out the changes of shade taking place nearly continuously during the manufacturing.

However, the continuous analysis of the dyeing phase may suitably be replaced, with acceptable approximation, by a discontinuous analysis in preset points. Firstly, it may be observed that to each manufacturing instant there corresponds a determined manufacturing length, i.e., the quantity of thread, in length units, manufactured until that instant.

Hereinafter, the manufacturing length variable will suitably be used as indication of the advance of the manufacturing, as the analysis on the sample thread is carried out in order to control the shade of the end product, which can be represented univocally only by using a length variable. The length of the sock can be immediately correlated to the manufacturing length, as the sample thread 14 used in a certain portion of sock has been subjected to the dyeing operation along with a corresponding portion of warp threads, which will then be woven and manufactured until making the end product.

To this end product there corresponds, as disclosed above, a certain manufacturing length.

Therefore, the sample thread sock can be divided into individual portions, each characteristic of a certain manufacturing length. Moreover, in order to effectively represent the manufacturing it is not necessary to use the whole sock made with the sample thread; it will suffice to take characteristic portions thereof. By way of example, the knitting phase produces a sock of about 250 cm starting from a 4000m beam. From the whole sock there may be taken, always by way of example, two cuts of about 35 cm, the first one at the start of each beam and the second one starting from the middle of the beam. These portions are already adequate to characterize in a sufficiently accurate manner the entire length of manufacturing of the beam, as the manufacturing rate is high.

The socks thus subdivided should undergo an enzymatic washing. This operation is necessary, since the excess of dye remaining onto the thread does not allow to appreciate the differences in shade existing in different points of the mesh. By discharging the dye in excess, there are highlighted the discontinuities or the changes of shade.

Moreover, prior to the washing phase, it is advisable to sew the edge thus produced by trimming it along the periphery thereof. This operation is necessary, since in the subsequent washing phase the untrimmed edges of the knitted fabric would run, causing the sock portions to curl. This would cause a non-homogeneous discharge of the dye. As mentioned above, the shade of the sock portion would match a certain portion of the end product.

However, surely the sock will not have the same shade of the end product, not having been woven together with the weft and not having undergone the same manufacturing of the warp yarn.

However, in the control of the manufacturing of Denim fabric, rather than the full assessment of the shade in itself, it is more important to detect the changes of shade that may be found within a manufacturing lot.

In fact, it is of absolute importance that within a single sale lot the changes of shade occurring be sufficiently limited. In fact, it is essential, above all for high-level textile producers, that all articles of clothing produced from a single lot of fabric appear with a constant shade.

Any change on the end product, due to the dyeing phase, can however be observed on the sample thread support made in the manner illustrated hereto.

In fact, the sample thread having undergone the same dyeing process of the end product, any dyeing problem will produce in both a deviation from the expected value of the shade proportional to the extent of the problem.

The sample thread support can be made in an extremely quicker manner with respect to the making of the end product, therefore allowing to carry out a preliminary analysis to check any dyeing problems, and, when possible, to intervene.

In fact, as illustrated in the foregoing, to each portion of sample thread support there can be correlated a manufacturing length. The support may be divided into discrete portions, so as to create support portions.

The portions will have a certain changeability in shade, due to the unavoidable problems taking place during the dyeing.

Such changes in shade can be easily checked also visually, in view of the modest sizes of the individual sample thread support portions. However, always due to the reduced sizes, even an automatic analysis by means of chromatic vision instruments is not excessively burdensome . Such an analysis will lead to cataloguing the support portions, sorting them out in groups characterized by the same shade. The characteristic shade of a group will deviate of a certain percentage with respect to the preceding one. Thus, there could be catalogued all the support portions describing the manufacturing length of the whole lot. Among the groups there could be singled out the one with the higher recurrence, corresponding to the reference shade of the manufacturing lot . The distribution of the other groups in which the portions are catalogued will be related to the pattern of the dyeing phase: in the absence of problems, the other groups will exhibit a very low recurrence, whereas, in case of unforeseen events taking place in the dyeing phase, the distribution becomes irregular with evident deviances from the group of higher recurrence. What is relevant is that, anyhow, also the end product will be characterized by having the same distribution of the shade, as the dyeing problems will have, apart from any corrective actions, the same effect both on the sample thread and on the end product. Therefore, the control method according to the present invention allows to carry out an accurate detection in a quick and effective manner, of the pattern of the shade pattern in the end product.

Knowing the pattern of the production shade entails several advantages.

In fact, upon having selected the maximum admissible deviation, it is possible to evaluate, prior to the weaving phase, which percentage of manufacturing will have to be discarded. In theory, this would also allow to prevent the weaving of that portion of warp not falling within the admissible range of shade, as to each support portion of sample thread there univocally corresponds a certain manufacturing length. The manufacturing length corresponding to the support portions not falling within the admissible range will have to be discarded; therefore their manufacturing could be left unfinished.

Or, where possible, corrective actions could be enacted in order to bring back said manufacturing length within the admissible range of shade.

Moreover, the method according to the present invention allows an easy cataloguing of the pattern of the dyeing phase, a pattern that could be analyzed, e.g., monthly, in order to single out any cyclical errors, due, e.g., to sudden thermal changes, or to unskilled operators .

Lastly, since the control may occur prior to the subsequent manufacturing of the product, the method allows to distinguish between changes of shade due to the dyeing phase and changes due to other factors.

As mentioned hereto, in fact, the distribution of the shade in the sample thread support is the same of that in the end product in case no other problems intervene after the dyeing phase. Then, any deviations among distributions may be due solely to the presence of additional problems, external to the dyeing phase. Lastly, this method allows to assess the behavior (sample) of novel yarns or to study novel dyes. The specificity and the peculiarity of the indigo dye are hardly reproducible in a laboratory, entailing high costs of production whenever the problem occurs. On the contrary, by replacing the sample thread with that to be tested there can be obtained important information over short times.

The present invention has hereto been described with reference to preferred embodiments thereof. It is understood that there could be other embodiments afferent to the same inventive kernel, all falling within the protective scope of the claims set forth hereinafter.

Claims

1. A dye-works control method in the manufacturing of Denim-type fabric, comprising the steps of:

- inserting a sample thread (13) along with a carpet of manufacturing threads (14);

- subjecting said sample thread (13) and said carpet of threads (14) to the same dyeing process;

- gathering said sample thread (13) at the end of the dyeing process;

- preparing a fabric support entirely made of said sample thread (13) ;

- correlating portions of said fabric support to respective manufacturing instants; - controlling the deviances of the shade of said fabric portion.

2. The dye-works control method according to the preceding claim, wherein the inserting of said sample thread (13) occurs in a position downstream of an inlet section (1) and upstream of the first of a plurality of vats () of dyeing section (2).

3. The dye-works control method according to one of the preceding claims, wherein the inserting of said sample thread (13) occurs at a distance ranging from 15 to 25 cm from the selvedge of said carpet of threads (14) .

4. The dye-works control method according to one of the preceding claims, wherein said sample thread (13) is of non-shot type, of twisted essentially pure cotton, with Ne substantially equal to 30/2.

5. The dye-works control method according to one of the preceding claims, wherein the gathering of said sample thread (13) occurs at an outlet section (3), upstream of a gathering section (4) of said carpet of threads (14) .

6. The dye-works control method according to one of the preceding claims, wherein said step of gathering said sample thread occurs by means of a reel winder (6) .

7. The dye-works control method according to one of the preceding claims, wherein the gathering of said sample thread (13) is stopped owing to anomalies in the dye-works.

8. The dye-works control method according to one of the preceding claims, wherein said carpet of threads

(14) is taken by a plurality of sectional beams (11) housed in said inlet section and gathered in a gathering beam (41) .

9. The dye-works control method according to the preceding claim, comprising a further step of marking said sample thread (13) at each replacing of said gathering beam (41).

10. The dye-works control method according to one of the preceding claims, wherein said step of preparing a fabric support entirely made of said sample thread (13) is carried out with a knitting machine, apt to make said fabric support in the form of a single continuous sock.

11. The dye-works control method according to the preceding claim, wherein said sock is cut into said portions apt to be correlated to respective manufacturing instants.

12. The dye-works control method according to the preceding claim, wherein said sock portions have respective edges sewn along the periphery thereof in order to avoid the run thereof.

13. The dye-works control method according to one of the preceding claims, comprising a further step of waxing said sample thread after the gathering of the same .

14. The dye-works control method according to one of the preceding claims, comprising a further step of carrying out an enzymatic washing of said fabric support entirely made of sample thread (13) .

15. A dye-works for Denim-type fabric, comprising a feeding section (1), apt to house a plurality of sectional beams (11), a dyeing section (2), comprising a series of vats (21) , downstream of each one thereof there being arranged a pair of rollers (22), an outlet section (3), and a gathering section (4), in which a carpet of threads (14) coming from said sectional beams (11) is, upon having completed the dyeing, gathered in a single beam (41), characterized in that it comprises a reel winder (6) apt to the gathering of a sample thread (13) dyed along with said carpet of threads (14) .

16. A dye-works for Denim-type fabric according to the preceding claim, wherein said reel winder (6) is electrically connected to said dyeing section (2).

17. Denim fabric or the like made according to the method of the claims 1 to 14.