EP4070091A1

EP4070091A1 - Method and apparatus for measuring whiteness and/or testing dye affinity of filaments

Info

Publication number: EP4070091A1
Application number: EP20812096.4A
Authority: EP
Inventors: Erich KURZBÖCK; Christoph RAMSAUER; Christa UNTERBERGER; Dominik OSTASZEWSKI; Christoph Schrempf
Original assignee: Lenzing AG; Chemiefaser Lenzing AG
Current assignee: Lenzing AG
Priority date: 2019-12-02
Filing date: 2020-12-01
Publication date: 2022-10-12
Also published as: EP3845899A1; BR112022010342A2; CN114729921A; WO2021110643A1; TW202134500A; US20230304988A1; KR20220108112A; JP2023504684A; TWI772985B

Abstract

The present invention relates to a method and to an apparatus for measuring the whiteness and/or testing the dye affinity of filaments.

Description

Method and device for measuring the degree of whiteness and / or checking the color of

Filaments

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

State of the art

Yarns and filaments, especially 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 which are produced 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, not only mechanical parameters but also the degree of whiteness and the ability to be dyed are relevant.

In the production of yarns, such as staple fiber yarns, filament yarns (mono- and multifilament yarns), which are hereinafter referred to as yarns / filament yarns, especially Lyocell filament yarns, the yarns / filament yarns produced are after the spinning process and possibly after optional aftertreatment Coils wound up and made available for further use. Due to the high production speeds, several thousand such bobbins may accumulate in a Lyocell system per day, which then have to be fed to the post-control of the desired properties. The results obtained should be as exact and reproducible as possible, especially with regard to the control of the degree of whiteness and the ability to be colored. At the same time, the effort (workload as well as space requirement of the devices) for these measurements should be as low as possible and an essentially automated process should preferably be realizable.

[0003] At present, test samples are knitted (knitted tube) for measuring the degree of whiteness and / or control of the color of yarns / filament yarns, in particular lyocell filament yarns, which are then used for measurement of the degree of whiteness and / or control of the color. Such methods are described in WO 99/40428 A1, US 2009/190132 A1, EP 1 006 225 A2 and in Wehlow A. et al, Prüfverfahren der Textil- und Clothingstechnik, 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 determinations that still have to be carried out manually, so that the Results through the influencing factor "human" is inevitable. It has been shown in particular that the results of these controls can be incorrect, for example because the knitted samples tend to falsify the measured values during the measurements due to different mechanical loads (eg 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 titre of the filaments to be tested. Due to the necessary exchange of the knitting heads, this leads to downtimes; automation or continuous testing of a large number of samples is also not possible. In addition, knitting machines are 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 of the present invention to provide a method and a device that enables whiteness and / or staining control, preferably both, in filament yarns, especially in Lyocell filaments, which overcome 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 available. Preferred configurations are given in the subclaims and the following description.

Brief description of the figure

Figure 1 shows schematically 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. In the following, the invention is first described in detail with regard to the claimed method. However, it is clear to the person skilled in the art that the following statements 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 type of yarn. Filament yarns, i.e. both mono- and multifilament yarns, can be tested, as well as other types of yarn, such as staple fiber yarns. For the sake of simplicity, these different types are referred to below with the term yarn / filament yarn.

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

According to the invention, it is essential that a woven sample is used for the whiteness and / or color control. By using a woven sample, the control of the properties relevant here does not suffer, in particular, 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 looms, are less prone to failure 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 denier and a known degree of whiteness are preferably used as warp threads. These warp threads can be Lyocell threads / filament threads, but the use of warp threads made of other materials is also possible and, in embodiments, is even preferred. For example, other natural yarns or synthetic yarns are suitable. An example of a synthetic thread are polyester threads, which are easily commercially available in a constant, standardized quality. By using such warp threads, due to the higher strength of these materials, the strength of the woven sample can again be increased, which further increases the advantage of using a woven sample (compared with knitted samples). The warp threads can be mono- or multifilament threads, all other types of yarns and twisted threads are also suitable. Since such ribbon weaving machines can produce fabrics of the same quality regardless of the titer of the weft threads (for example by adjusting the number of wefts, something that is automatically included in the production of the test pieces Taking into account the titer of the filament to be evaluated), no special adaptation of the ribbon loom as such to different yarn / filament yarn types (titer) is necessary. In this way, samples can be generated from different types of filament yarns without a great deal of equipment (no modification work necessary, unlike with knitting machines, where the knitting heads need to be replaced depending on the titer of the filament yarns to be tested).

Since the introduction of filament yarns in such ribbon looms is possible through the use of commercially available yarn feeders that 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 Filament yarn inserted directly into the weaving needle by a machine and then fixed, sample patterns (for example woven samples of about 6 x 10 cm) of yarns / filament yarns from different bobbins can be generated continuously. By means of a corresponding control, for example the pausing of the weaving needle, which results in filament yarn connections between the individual woven test pieces, it is easy to distinguish between the individual woven samples. This woven construction also forms a connection between the respective beginning or end of the specimen to be tested, so that with regard to the still ongoing control of the degree of whiteness and / or the ability to be colored, a continuous and also automated process control remains possible.

As already stated, a suitable yarn, preferably mono- or multifilament yarn, can be used as the warp thread. This can be prepared for weaving, for example by providing a size or by preparation 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. With the same type of weave (weaving conditions), 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 thread, so that the woven sample piece will have a dominant, weft-accentuated side on which the relevant measurements can then be carried out. By adjusting the weft density, yarns / filament yarns of different titers can also be processed into comparable fabric samples. In general, with finer titers, the weft density is increased in order to ensure, in particular, sufficiently high fabric strength values and weft thread densities as a measuring surface. Exemplary combinations of titer of the yarns / filament yarns to be evaluated and Weft densities are as follows: (titer weft thread / weft density) 40 dtex / 26 wefts per cm; 500 dtex / 10 wefts per cm (when using a warp beam with 25 warp threads per cm and a satin weave 3/1).

It has been shown that in this way yarns / filament yarns with different titers (weft thread sizes), for example from 10 to 500 dtex, can easily be processed into fabric samples for the subsequent whiteness determination and / or color control.

By using woven samples it is already possible to overcome several of the disadvantages occurring in the prior art. Thus, sample pieces of bobbins can be produced in an automated and continuous manner, since an automated and continuous sample production can be realized with commercially available ribbon looms and yarn feeders. These systems are also less prone to malfunctions than knitting machines and there is no downtime due to the need to replace the knitting head when producing knitted samples (for checking bobbins with different filament yarn counts). At the same time, the linking or the automated direct addition of yarn / filament yarn simplifies further continuous evaluation of the woven samples without, for example, manual links / connections having to be created. Compared to the production of knitted samples, the production of woven samples is also faster, which increases the possible bobbin throughput. In addition, the woven samples are mechanically less susceptible, so that the measurements of whiteness and / or dyeability are less susceptible to errors / deviations. By using a yarn / filament yarn with known properties as a warp thread, this can also theoretically be viewed as an internal standard in the fabric samples and used accordingly in subsequent evaluations.

[0013] The samples produced as described above can then be fed to further evaluation individually and manually, but preferably automatically and continuously.

An evaluation to be carried out according to the invention is the determination of the degree of whiteness. As already described above, this determination takes place on the dominant side with the emphasis on the shot. This makes the influence of the warp threads used irrelevant for the measurement. The conditions and apparatus required to determine the degree of whiteness are known to the person skilled in the art. Known, commercially available measuring devices can be used. Another evaluation to be carried out according to the invention is a staining 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 color in a dye padding, followed by fixing, for example in a steamer, washing and drying. Suitable dyes are in particular direct dyes, such as solophenyl blue. With regard to the evaluation and comparability of the measurement results, constant staining conditions, which are known to the person skilled in the art, as well as the conditions in the individual steps (such as staining, fixing, washing, drying) are essential. The method according to the invention, which can be carried out continuously, makes it possible to minimize the use of chemicals in the staining control, in comparison with the discontinuous staining controls with knitted samples.

After the coloring is complete, the color value is determined. Again, this takes place on the dominant weft-emphasized 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 for this are also known to the person skilled in the art. Known and commercially available measuring devices 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-accentuated side of the woven sample piece and / or the color value of the yarn / filament yarn after coloring the woven sample piece on the dominant weft-emphasized side of the woven specimen is determined.

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 sequence. Due to the connection between the individual woven test pieces already described above, these can in turn be guided continuously and automatically through the individual steps of determining the degree of whiteness and the color value.

After the color value has been determined, the samples can be sent for storage. For this purpose, these can be wound up, for example, so that rolls are obtained with the individual, preferably still connected, test pieces. Such roles can be stored easily and with little space requirement, another advantage over this the use of knitted samples, as the space required for storage is greater and also involves 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 coloring and color value determination take different lengths of time, the sample pieces are temporarily stored in embodiments between the above-mentioned steps. Due to the normally higher time requirement of the dyeing step in comparison with the weaving of the test pieces and the determination of the degree of whiteness and color value measurement, intermediate storage of the woven test pieces is helpful in many embodiments, especially before the dyeing step. In the case of continuous processes, such intermediate storage can also take place by adapting the length of the connections (the link between the end of the filament yarn and the beginning of the filament yarn of two filament yarns, for example from spools to be tested one after the other) between the individual woven test pieces. In this way, a largely automated and continuous process can be implemented. The interconnected woven test pieces 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 thus comprise the following steps:

1.) The spools of filament yarn from filament production (for example from the dishwasher) are fed into the automatic yarn feeder (1) one after the other. The beginning of a new filament (from a new bobbin) can be brought into the weaving machine and automatically linked to the end of the filament from the previous bobbin. Alternatively, each yarn / filament yarn can also be freshly inserted directly (see also [0012]).

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

Loom (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 sample has been woven (for example 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 removed (for the possible connection with the filament yarn of the next bobbin and to control / enable the optional intermediate storage times, for example in a storage (3) the individual, subsequent further steps), the filament yarn is cut so that the spool can be packaged, stored and made available for further use. 4.) The woven sample is now fed to the whiteness measurement (4) and then an optional intermediate storage in a further storage (5) can take place again.

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

Dye pad (6), followed by steam treatment (7) to fix the dye, a washing stage (8) and drying (9). Optionally, prior to the subsequent color value determination (11), renewed intermediate storage in a memory (10) can then 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, in particular the bobbin number (product information on the filament or filament yarn, such as titer, etc.), weaving parameters (number of wefts but also type and titer of the warp thread), result of the whiteness measurement, parameters of the coloring are preferred , Result of the color value determination, day of production of the sample, etc. automatically saved by suitable processes so that a data set with the relevant information is available for each evaluated coil. This can be done by automatically recording the operating parameters of the loom, the dye pad, etc., as well as by corresponding recording of the measurement results. The systems required for this are known to the person skilled in the art. These data can then also be fully or partially fixed in the form of a label on the sample piece itself, so that a direct identification of the sample pieces is also possible. Labels can be connected to the test piece in a suitable manner (sticking, attaching, etc.) or printed directly on the test piece, for example as a barcode, etc. The devices etc. necessary for this are known to the person skilled in the art.

In this way, a complete data set of relevant information is generated 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 loom for producing a woven sample piece and at least one unit for determining the whiteness of the sample piece or one unit for coloring and determining the color value of the sample piece. Preferably these devices are through connected suitable devices that allow a continuous and largely automated guidance of a plurality of optionally interconnected sample pieces through the device.

With reference to Figure 1, such a device can thus have the following components:

A.) An automatic thread feeder (1). This feeds 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 a weft thread in the weaving machine and processed into a woven sample piece.

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

C.) A dye padding (6) can then be provided, followed by one

Damper (7) to fix the staining, a washer (8) and a dryer (9). Optionally, a new memory (10) can then be provided in front of the subsequent unit for color value determination (11).

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

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

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

Due to the continuous dyeing of the woven test pieces, the use of materials and the energy consumption in these steps can be significantly reduced compared to discontinuous processes, in particular with knitted test pieces.

Overall, a significantly improved system for recording relevant data for yarns / filament yarns, in particular Lyocell filament yarns, is provided.

Claims

Expectations

1. A method for determining the 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 as a weft thread is used, and wherein the degree of whiteness is determined on the dominant weft-stressed side of the woven specimen and / or the color value of the yarn / filament yarn, after dyeing the woven specimen, is determined on the dominant weft-stressed side of the woven specimen.

2. The method according to claim 1, wherein a Lyocell filament yarn or a synthetic fiber with a titer 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, the whiteness is first determined and then, after the test piece has been colored, the color value is determined.

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

5. The method of claim 4, wherein the individual coupons are connected to one another by nonwoven warp sections.

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

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

8. Device for determining the whiteness and / or the color value of a yarn / filament yarn, in particular a Lyocell filament yarn, comprising a loom in which the yarns / filament yarns to be evaluated are processed into woven test pieces, as well as a unit for determining the whiteness and / or a unit for determining the color value of the yarn / filament yarn on the basis of the woven test piece.

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

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

11. 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 the data from the loom, the unit for measuring the degree of whiteness and the unit for determining the color value.