Method and device for whiteness measurement and/or staining control

filaments

The present invention relates to a method and a device for measuring the degree of whiteness and/or checking the dyeing of yarns and filaments.

State of the art

Yarns and filaments, in particular those based on cellulose, are produced on a large scale and used in many areas, such as the textile industry, but also in technical areas. An example of such filaments are filaments made by the lyocell process from a composition of cellulose in a solvent, usually a mixture of water and N-methylmorpholine-N-oxide (NMNO). With regard to the quality control of the filaments produced, the degree of whiteness and the ability to be dyed are relevant in addition to mechanical parameters.

In the production of yarns, such as staple fiber yarns, filament yarns (mono- and multifilament yarns), which are referred to below as yarns/filament yarns, in particular Lyocell filament yarns, the yarns/filament yarns produced are after the spinning process and, if necessary, after optional post-treatments Spools wound up and made available for further use. Due to the high production speeds, several thousand such spools may be produced in a lyocell plant per day, which then have to be subjected to the post-control of the desired properties. The results obtained should be as exact and reproducible as possible, particularly with regard to controlling the degree of whiteness and the ability to be colored. At the same time, the effort (expenditure of work as well as space required for the devices) for these measurements should be as low as possible and preferably an essentially automated process should be realizable.

[0003] Currently, test samples are knitted (knitted tube) for whiteness measurement and/or dyeing control of yarns/filament yarns, in particular Lyocell filament yarns, which are then used for whiteness measurement and/or dyeing control. Such methods are in WO 99/40428 A1, US 2009/190132 A1, EP 1 006 225 A2 and in Wehlow A. et al, Test Methods in Textile and Clothing Technology, Springer, 2000, Chapter 8.1, pages 727 to 776 and Abdel-Fattah M Seyam et al, Fibers and Polymers, The Korean Fiber Society, Heidelberg, Vol. 13, No. 6, August 1, 2012. These are largely still to be carried out manually, so that a scattering of the

Results due to the influencing factor "human" is unavoidable. In particular, it has been shown that the results of these checks can be incorrect, for example because the knitted samples tend to falsify the measured values ​​due to different mechanical loads (e.g. stretching of the sample). A comparison with a standard material is also difficult with such samples. Furthermore, the respective knitting heads must be adapted to the titers of the filaments to be tested. This leads to downtimes due to the necessary replacement of the knitting heads, automation or continuous testing of a large number of samples is also not possible. In addition, knitting machines are also comparatively prone to failure, which can again lead to downtimes. The space required for storing the samples is also comparatively high.

Object of the present invention

It is therefore the object underlying the present invention to provide a method and a device which enables whiteness and/or staining control, preferably both, in filament yarns, in particular in lyocell filaments, which overcomes the disadvantages of the prior art .

Brief description of the invention

The present invention therefore provides a method according to claim 1 and an apparatus according to claim 8. Preferred configurations are specified in the subclaims and the following description.

Brief description of the character

[0006] FIG. 1 schematically shows a process sequence of the present invention or a schematic representation of a device according to the invention.

Detailed description of the invention

It has unexpectedly been found that the disadvantages of the prior art can be overcome by using woven samples instead of knitted samples. The invention is first described in detail below with regard to the claimed method. However, it is clear to the person skilled in the art that the following explanations also apply with regard to the claimed device.

With regard to the yarns/filament yarns to be evaluated, the present invention is not limited to one yarn type. Filament yarns, i.e. both mono and multifilament yarns, can be tested, as well as other yarn types such as staple fiber yarns. For convenience, these different types are referred to below with the term called yarn/filament yarn.

As already stated, the yarns/filament yarns are preferably lyocell yarns/filament yarns. However, other yarns/filament yarns based on cellulose can also be used. Also particularly suitable are cellulosic yarns/filament yarns obtained by the viscose process, the cupro process or by regeneration from ionic liquids.

According to the invention it is essential that a woven sample is used for the degree of whiteness and/or staining control. By using a woven sample, the control of the properties relevant here does not suffer from the fluctuations and irregularities in the measurements, which occur due to the lower mechanical strength of the knitted samples in the prior art. At the same time, the devices to be used to produce the woven samples, preferably ribbon weaving machines, are less prone to malfunction than knitting machines, so that a larger number of bobbins with yarn/filament yarn can be tested per unit of time.

In the production of the woven samples, which are given the shape of a rectangular fabric, for example, the yarns/filament yarns to be tested are preferably used as weft threads. Standard filament yarns of a precisely defined titer and a known degree of whiteness are preferably used as warp threads. These warp threads can be lyocell yarns/filament yarns, but the use of warp threads made of other materials is also possible and even preferred in embodiments. For example, other natural yarns or synthetic yarns are suitable. An example of a synthetic thread is polyester thread, which is readily available commercially in consistent, standardized quality. Due to the higher strength of these materials, the use of such warp threads can again increase the strength of the woven sample, which further increases the advantage of using a woven sample (compared to knitted samples). The warp threads can be monofilament or multifilament threads, but all other types of yarns and threads are also suitable. Because ribbon looms of this type can produce fabrics of the same quality regardless of the count of the weft threads (e.g. by adjusting the number of wefts, something that is automatically carried out during the production of the test pieces under

The titre of the filament to be evaluated can be taken into account), no special adaptation of the ribbon loom as such to different yarn/filament yarn types (titre) is necessary. In this way, samples can be generated from different types of filament yarns without great expenditure on equipment (no conversion work necessary, unlike in the case of knitting machines, in which the knitting heads have to be exchanged depending on the titer of the filament yarns to be tested).

Since the introduction of filament yarns into such ribbon looms is possible through the use of commercially available yarn feeders, which either automatically connect the beginning of a new filament yarn (typically from a spool) to the end of the previously fed filament yarn, or the beginning of a new one If the filament yarn is fed directly to the weaving needle by an automatic machine and then fixed, samples (e.g. woven samples of around 6 x 10 cm) can be produced continuously from yarns/filament yarns on different spools. By appropriate control, for example pausing the weaving needle, which results in filament yarn connections between the individual woven samples, it is easy to distinguish between the individual woven samples. This woven construction also forms a connection between the respective beginning and end of the sample to be tested, so that a continuous and also automated process control remains possible with regard to the still taking place control of the whiteness and/or the dyeability.

As already stated, a suitable yarn, preferably monofilament or multifilament yarn, can be used as the warp thread. This can be prepared for weaving, for example by providing a size or by preparing it with an oil. Twisted, twisted, intermingled or flamed yarns/filament yarns are particularly suitable. Yarns/filament yarns of all these variants with a titer of 60 to 160 dtex, preferably 80 to 120 dtex, are particularly suitable. If the type of weave (weaving conditions) remains the same, these warp threads only have a negligible influence on the properties that are relevant and to be determined here. The yarn/filament yarn to be tested is used as a weft yarn so that the woven sample will have a dominant, weft-accentuated side on which the relevant measurements can then be made. By adjusting the weft density, yarns/filament yarns of different counts can also be processed into comparable fabric samples . In general, with finer counts, the weft density is increased, in particular to ensure sufficiently high fabric strength values ​​and weft thread densities as the measuring surface. Exemplary combinations of titers of the yarns/filament yarns to be evaluated and

Weft densities are as follows: (weft yarn count/weft density) 40 dtex/26 picks per cm; 500dtex/10 picks per cm (when using a warp beam with 25 warp threads per cm and satin weave 3/1).

It has been shown that in this way yarns/filament yarns with different titres (weft thread counts), for example from 10 to 500 dtex, can be processed into fabric samples for subsequent whiteness determination and/or dyeing control without any problems.

By using woven samples, it is already possible to overcome several of the disadvantages of the prior art. Sample pieces of bobbins can thus be produced in an automated and continuous manner, since automated and continuous sample production can be implemented using commercially available ribbon weaving machines and yarn feeders. These systems are also less prone to failure than knitting machines and there are no downtimes due to the exchange of the knitting head (for checking bobbins with different filament yarn counts) that may be necessary during the production of knitted samples. At the same time, the linking or the automated direct addition of yarn/filament yarn to the woven samples simplifies further continuous evaluation without, for example, having to create links/connections manually. Compared to the production of knitted samples, the production of woven samples is also faster, which increases the potential package throughput. The woven samples are also mechanically less susceptible, so the measurements of brightness and/or dyeability are less prone to error/variance. By using a yarn/filament yarn with known properties as the warp thread, this can theoretically also be regarded as an internal standard in the fabric samples and used accordingly in subsequent evaluations.

The samples produced as described above can then be fed individually and manually, but preferably automatically and continuously, for further evaluation.

[0014] An evaluation to be carried out according to the invention is the determination of the degree of whiteness. As already described above, this determination is made on the dominant shot-prone side. As a result, the influence of the warp threads used becomes irrelevant for the measurement. The conditions and apparatus required to determine the degree of whiteness are known to those skilled in the art. Known, commercially available measuring apparatus can be used.

Another evaluation to be carried out according to the invention is a dyeing control of the yarns/filament yarns. For this purpose, the woven sample is dyed using a standardized process and the color value is then determined. Here, the fabric is usually first subjected to an application of dye in a dye padder, followed by fixing, for example in a steamer, washing and drying. Suitable dyes are, in particular, direct dyes such as solophenyl blue. Essential with regard to the evaluation and comparability of the measurement results are constant staining conditions, which are known to the person skilled in the art, as are the conditions in the individual steps (such as staining, fixing, washing, drying). The method according to the invention, which can be run continuously, makes it possible to minimize the use of chemicals in the staining control, in comparison with the non-continuous staining controls with knitted samples.

[0016] After the coloring is completed, the color value is determined. This is again done on the dominating weft side of the fabric, so that again the influence of the warp thread on the result of the determination is negligible. The necessary conditions and systems are also known to the person skilled in the art for this purpose. Known and commercially available measuring apparatus can also be used.

According to the invention, the method according to claim 1 is designed in such a way that the whiteness of the yarn/filament yarn is determined in a whiteness measuring station on the dominant weft side of the woven sample piece and/or the color value of the yarn/filament yarn after dyeing of the woven sample piece is determined on the dominant weft side of the woven sample is determined.

[0017] According to the invention, both a determination of the degree of whiteness and a determination of the color value are preferably carried out in this order. Through the above-described connection between the individual woven specimens, these can in turn be continuously and automatically through the individual n steps of determining the degree of whiteness and the color value.

After the color value has been determined, the samples can be stored. For this purpose, they can be wound up, for example, so that rolls with the individual test pieces, which are preferably still connected, are obtained. Such rolls can be stored easily and with little space requirement, a further advantage over the use of knitted samples, since the space requirement for storage is larger and also associated with greater manual effort.

Since on the one hand the production of the woven test pieces and on the other hand the determination of the degree of whiteness and the staining and color value determination take different lengths of time, the test pieces are temporarily stored between the above-mentioned steps in embodiments. Due to the normally longer time requirement of the dyeing step, compared to the weaving of the test pieces as well as the whiteness determination and color value measurement, intermediate storage of the woven test pieces is particularly helpful in many embodiments before the dyeing step. In the case of continuous processes, such intermediate storage can also be effected by adjusting the length of the connections (the link between the end and beginning of filament yarns of two filament yarns, which originate, for example, from spools to be tested one after the other) between the individual woven specimens. In this way, a largely automated and continuous process can be implemented. The woven test pieces that are connected to one another are continuously fed to the individual steps of the process by suitable transport systems.

With reference to FIG. 1, a method according to the invention can therefore include the following steps:

1.) The bobbins with filament yarn originating from the filament production (e.g. from the dishwasher) are introduced one after the other into the automatic yarn feeder (1). The beginning of a new filament (from a new spool) can be introduced into the weaving machine and automatically linked to the end of the filament of the previous spool. Alternatively, each yarn/filament yarn can also be directly inserted fresh (see also [0012]).

2.) A sufficient length of filament yarn is drawn off the spool and placed in a

Weaving machine (2), for example a ribbon loom, woven into a sample piece. The filament yarn to be tested is used as a weft thread.

3.) After a sufficiently large test piece has been woven (e.g. with a

width of about 10 cm and a length of 6 cm) and a sufficiently long end piece of the filament yarn was additionally drawn off (for the possible connection with the filament yarn of the next spool and to control/enable the optional intermediate storage times, for example in a storage (3) between the individual further steps that follow), the filament yarn is cut so that the bobbin can be packed, stored and made available for further use.

4.) The woven test piece is now fed to the degree of whiteness measurement (4) and then an optional interim storage can take place in another store (5).

5.) The sample piece is then stained, for example in a

Dyeing padder (6), followed by a steam treatment (7) to fix the dyeing, a washing stage (8) and drying (9). Optionally, prior to the subsequent determination of the color value (11), renewed intermediate storage in a memory (10) can take place.

6.) After going through the steps described above, the test pieces can be wound up by a winder (12) and then stored, for example in the form of a roll.

In the method according to the invention, the relevant data are preferred, i.e. in particular the bobbin number (product information on the filament or filament yarn, such as titer, etc.), weaving parameters (number of picks but also type and titer of the warp thread), result of the whiteness measurement, parameters of the dyeing , result of the determination of the color value, day of the production of the sample piece, etc. are automatically stored by suitable methods, so that a data set with the relevant information is available for each coil evaluated. This can be done by automatically recording the operating parameters of the weaving machine, the dyeing pad, etc., and by corresponding recording of the measurement results. The systems required for this are known to those skilled in the art. This data can then also be fixed in whole or in part in the form of a label on the sample piece itself, so that direct identification of the sample pieces is also possible. Labels can be attached to the test piece in a suitable manner (glued, attached, etc.) or printed directly onto the test piece, for example as a bar code etc. The devices etc. required for this are known to the person skilled in the art.

[0 022] This creates a complete data set of relevant information for each coil, which enables the relevant product parameters to be stored via the unique identification of the sample piece and the coil.

According to the invention, in addition to the method described above, a device for the continuous and preferably automated production and evaluation of yarns/filament yarns is also provided. This device comprises at least one weaving machine for producing a woven test piece and at least one unit for determining the degree of whiteness of the test piece or a unit for coloring and determining the color value of the test piece. Preferably, these devices are through

connected suitable devices that allow a continuous and largely automated guidance of a plurality of optionally interconnected specimens through the device.

With reference to FIG. 1, such a device can therefore have the following components:

A.) An automatic yarn feeder (1). This introduces the beginning of a filament yarn from a bobbin into a weaving machine (2) where this beginning is optionally automatically linked to the end of the filament yarn from the previous bobbin. Alternative configurations are possible as described in paragraph [0012]. An automatic inserter is then used for this purpose, for example. The yarn/filament yarn to be evaluated is used as weft thread in the weaving machine and processed into a woven test piece.

B.) A store (3) can be provided after the weaving machine. A whiteness meter (4) is then provided, followed again by an optional memory (5).

C.) A dye padder (6) can then be provided, followed by a

Damper (7) for fixing the dyeing, a washer (8) and a dryer (9). A renewed memory (10) can then optionally be provided upstream of the subsequent unit for color value determination (11).

D.) Finally, a unit for producing a compact form of storage for a large number of specimens can be provided, such as a winder (12) which rolls up the specimens into a roll of retaining samples which can be stored easily.

Not shown in Figure 1 is necessary for a continuous and automated procedure submission for continuous and controlled guiding the specimens through the device. However, such devices are known in particular to those skilled in the field of filament yarn production and weaving machines, for example roller and roller systems.

With the method according to the invention and the device according to the invention, yarn/filament yarn samples can therefore be processed continuously and automatically into test pieces and then subjected to a whiteness measurement and/or color value determination after dyeing, so that relevant yarn/filament yarn data can be obtained in a reproducible manner be able. The space requirement of the device is lower compared to methods that work with knitted test pieces and the throughput of bobbins is also significantly higher according to the invention (no exchange of the knitting heads, the system as a whole is more robust and less susceptible to faults due to the use of a weaving machine). The data obtained by the method according to the invention are subject to fewer errors with regard to the yarns/filament yarns to be measured/evaluated, since the woven specimens are less stretchable, the titre of the yarn/filament yarn due to the use of a woven specimen has no influence on the determinations of the whiteness and color value. The space requirements for storing the retained samples are also lower, so that costs can also be saved here. Likewise, the scattering of the results, which occurs with manual and batch measurements, can be significantly reduced through the automatic and continuous acquisition of the relevant data.

The continuous dyeing of the woven test pieces can also significantly reduce the use of material and energy consumption in these steps compared to discontinuous methods, in particular with knitted test pieces.

[0028] Overall, therefore, a significantly improved system for acquiring relevant data for yarns/filament yarns, in particular Lyocell filament yarns, is provided.

Expectations

1. A method for determining the degree of whiteness and/or the color value of a cellulosic yarn/filament yarn, in particular a Lyocell filament yarn, characterized in that a woven test piece is produced from the yarn/filament yarn to be evaluated, the yarn/filament yarn to be evaluated being used as the weft thread and wherein the whiteness is determined on the dominant fill side of the woven sample and/or the color value of the yarn/filament yarn, after dyeing the woven sample, is determined on the dominant fill side of the woven sample.

2. The method according to claim 1, wherein a Lyocell filament yarn or a synthetic fiber with a titre of 60 to 160 dtex is used as the warp thread.

3. The method according to any one of claims 1 or 2, wherein after the production of the woven test piece, first the degree of whiteness is determined and then, after the test piece has been dyed, the color value is determined.

4. The method according to any one of claims 1 to 3, wherein different yarns / filament yarns are successively processed in a continuous process to woven test pieces and these continuously determine the degree of whiteness and the determination of the color value after dyeing the test pieces are subjected.

5. The method of claim 4, wherein the individual specimens are joined together by non-woven warp sections.

6. The method according to claim 4 or 5, wherein the test pieces are wound up into a roll after the determination of the degree of whiteness and the color value.

7. The method according to any one of claims 1 to 6, wherein the staining is carried out by using a direct dye.

8. Device for determining the degree of whiteness and/or the color value of a yarn/filament yarn, in particular a lyocell filament yarn, comprising a weaving machine in which yarns/filament yarns to be evaluated are processed into woven specimens, and a unit for determining the degree of whiteness and/or a unit for determining the color value of the yarn/filament yarn from the woven sample.

9. Apparatus according to claim 8, comprising an automatic yarn feeder for introducing a yarn/filament yarn into the loom.

10. Device according to claim 8 or 9, wherein the unit for determining the color value additionally comprises a dye padder, a steam unit for fixing, a washer and a dryer.

11. An apparatus according to any one of claims 8 to 10, further comprising a unit for continuously feeding a plurality of specimens through the apparatus.

12. Device according to one of claims 8 to 11, further comprising systems for the automated acquisition of data from the weaving machine, the unit for measuring the degree of whiteness and the unit for determining the color value.