TW202129107A - Roller surface - Google Patents

Abstract

The present invention relates to the surface adaptation of a roller to be employed in the production of cellulose filament yarns.

Description

Roller surface

The present invention relates to the surface adjustment of the drum to be used for the manufacture of cellulosic filament yarns.

Continuous filament yarns are widely used in the textile industry to manufacture fabrics with significantly different characteristics from fabrics made from yarns made from staple fibers. Continuous filament yarn is a yarn in which all fibers are continuous in any length of the yarn. Continuous filament yarns are usually composed of 10 to 300 or more individual filaments that are all parallel to each other and parallel to the axis of the yarn at the time of manufacture. The yarn is manufactured by extruding a solution or melt of a polymer or polymer derivative, and then winding the manufactured yarn on a bobbin or reel, or forming a yarn cake by centrifugal winding.

Synthetic polymer continuous filament yarn is very common. For example, nylon, polyester and polypropylene continuous filament yarns are used in various fabrics. It is manufactured by melt-spinning molten polymer through a spinning nozzle with a number of holes corresponding to the number of filaments required for the manufactured yarn. After the molten polymer starts to solidify, the yarn can be stretched to align the polymer molecules and improve the properties of the yarn. Continuous filament yarns can also be spun from cellulose derivatives such as cellulose diacetate and cellulose triacetate by dry spinning. The polymer is dissolved in a suitable solvent and then extruded through a spinning nozzle. The solvent evaporates quickly after extrusion, causing the polymer to precipitate in the form of filaments to form yarn. The newly made yarn can be stretched to orient polymer molecules.

One way to manufacture filaments and fibers based on cellulose is the so-called lyocell process. Lyocell technology is to directly dissolve cellulosic wood pulp or other cellulose-based raw materials in polar solvents (such as n-methyl morpholine n-oxide), hereinafter referred to as "oxidation "Amine") is a technology based on the production of viscous high-shear viscosity-reducing solutions that can form a series of useful cellulose-based materials. Commercially, this technology is used to manufacture cellulosic staple fibers that are widely used in the textile and non-woven fabric industries (available from Lenzing AG, Lenzing, Hungary, under the trade name TENCEL®). Other cellulosic products from Lyocell technology such as filaments, membranes, shields, beads and non-woven nets have also been disclosed.

EP 823945 B1 discloses a method for manufacturing cellulose fibers, which includes extruding and coagulating a cellulose spinning solution according to a lyocell process, compulsorily including drawn filaments and cutting the filaments into cellulose fibers that can be used in various application fields step. According to the teachings of the prior art, the process steps of drawing the coagulated cellulose filaments are necessary to obtain staple fibers with the desired balance of properties. EP 0 853 146 A2 discloses a method for preparing cellulose-based fibers. According to the teachings of this document, two different raw materials with very different molecular weights are mixed to obtain fibers. WO 98/06754 discloses a similar method, which requires two different raw materials to be dissolved separately before blending the prepared solution to obtain the spinning solution. DE 199 54 152 A1 discloses a method for preparing fibers, in which a spinning solution with a relatively low temperature is used. WO 97/23667 discloses a method for manufacturing lyocell fibers. DE 10 2005 040 001 A1 discloses a device that can be used to manufacture lyocell fibers. In Journal of Food Engineering 64 (2004), 63-79, O. Santos et al. disclosed information about the surface of modified stainless steel that aims to reduce fouling. The benefits of cellulosic filament yarns made from lyocell spinning solutions have been described (Krüger, Lenzinger Berichte 9/94, S. 49 ff.). However, due to the increased demand for spinning efficiency, attempts have been made to increase the spinning speed in the lyocell process to a value of several hundred meters per second. However, at such high spinning speeds, various problems may occur, including an unsatisfactory high percentage of defects in individual filaments manufactured, which can cause a high percentage of products to be unsuitable for future use and/or cause production to stop.

During the lyocell process, after the initial filaments are coagulated in the coagulation tank, various rollers are used to transport the filaments and/or tows to another stage of the process, such as washing. At first, the filaments or tows are still vulnerable to damage and/or improperly adhere to each other when they come into contact. Therefore, care must be taken that the filaments or tows passing around the drum will not cause unwanted effects on the manufactured filaments. Impact. Examples of such negative effects are sliding due to unsatisfactory adhesion to the drum surface, axial movement of the filaments or tows on the drum surface (ie, lateral movement on the drum surface, so There will be undesired contact between adjacent filaments or tows), and due to the effect of excessive adhesion to the surface of the drum, so when the filaments or tows are separated from the surface of the drum, the filaments or tows are Generate mechanical force.

Therefore, the high-speed preparation of continuous filament lyocell yarn poses a new process challenge. It would be beneficial if slippage or other problems during the process can be minimized in a reliable manner. In particular, if it can be minimized or completely avoided not only during the initial stage of the process (immediately after spinning and the initial washing step) but also in the later stages of the process (such as applying additional substances, such as post-treatment (avivage) procedures or Such problems during the application of oils, moisturizing compositions, etc.) can be beneficial.

Therefore, the object of the present invention is to propose a method to prevent defects in lyocell filaments or tows and a method to prevent manufacturing problems caused by slippage during the production of lyocell filaments, especially at high speeds.

Therefore, the present invention proposes a roller as defined in Claim 1 and a method as in Claim 2. The preferred embodiments are in the claims 3 to 11 and this specification, and in the use claims 12 to 15.

As is well known in the art, the lyocell process involves extruding filaments through a nozzle after preparing a spinning solution, in most cases, initially cooling in an air gap, and then solidifying in a tank. Afterwards, the filament or tow is usually taken up by a guide roller to guide the product to other process steps, such as liquid removal and washing steps. In addition, during these stages, rollers are used to move the filaments or tows to subsequent process steps. The additional stage of filament manufacturing may be a stage of applying another substance to the filament or filament yarn, such as applying a post-treatment agent or the like.

Regarding the drum, especially the initial guide drum that winds up the filament after it leaves the coagulation tank, but it can also be the next drum and any other drum. It is important to perform additional processing steps as carefully as possible to avoid filaments. It is subjected to forces that are harmful to it, and at the same time, especially during the contact with the first few rollers, the movement of the filaments and/or tows is avoided to prevent the filaments and/or tows from contacting each other. In the initial stage after the solidification, the filaments are still subject to mechanical influences and undesired contact points between individual filaments and/or tows are easily generated. As this leads to further downstream problems during filament processing, it is related to careful control of these process stages. However, since production speed is the most important factor in commercial considerations, no compromise can be made on production speed. However, similar considerations also apply to the later stages of the process. The filament or filament yarn must again be transported around the rollers of the individual process steps as carefully as possible (especially to avoid slippage). When knotting) causes harmful effects, such as filament breakage or production problems.

In particular, since sliding may particularly cause various problems that may require an extremely undesirable overall process stop, it is necessary to convey the filaments and/or tows through the drum without sliding. As mentioned above, these requirements on the surface of the drum are not easily met, and the different requirements due to the nature of the fibers contradict each other. In addition, these requirements may be different in the different production stages mentioned above. In order to be able to transport quickly without sliding and without axial movement of filaments and/or tows, the adhesion to the surface should be as high as possible. At the same time, the filaments or tows themselves must be separated from the surface of the drum at a given point in time (ie, the filaments and/or tows detach from the surface of the drum without generating undesirable high mechanical forces on the filaments or tows), which requires The lowest possible adhesion. Therefore, solutions need to be found to comply with these conflicting requirements.

According to the present invention, it has been found that if the surface of the roller to be in contact with the lyocell filament or tow is selected so that the surface of the roller contains the first part showing the surface tension, so that depending on the liquid adhering to the filament or yarn, it satisfies One of the following conditions can satisfy these conflicting requirements: a) If the surface tension of the liquid is 45 mN/m or higher, the surface tension of the first part is 0.25 to 3.5 times, preferably 0.35 to 2.5 times, more preferably 0.4 to the surface tension of the liquid 0.8 times the range; or b) If the surface tension of the liquid is less than 45 mN/m, the surface tension of the first part is 0.5 to 10 times, preferably 0.8 to 2.5, more preferably 1 to 2 times the surface tension of the liquid Scope. In addition to the surface structure explained herein, other aspects of the design of the drum according to the principle of the present invention are based on common drum designs (such as diameter, etc.), so these details are not further explained in this article. It has been found that by adjusting the surface tension of the first part of the drum surface as described above, the filaments and/or yarns can be guided around the drum in individual process steps without harmful effects on the filaments or yarns. Taking the washing step as an example, the above principle means (using water as the washing liquid with a surface tension of about 72.8 mN/m) the first part can have a surface tension of 254.8 mN/m to 18.2 mN/m. In the case of a low surface tension liquid, for example, after finishing the composition with a surface tension of about 29 mN/m, the surface tension of the first part may range from 14,5 mN/m to 290 mN/m. The surface tension in the above range provides the necessary adhesion of the filament or tow, which, as described above, prevents the filament and/or tow from sliding and moving axially on the surface of the drum. However, there is also a need for a roller that can easily remove filaments or tows from the surface of the roller at a desired position. As mentioned above, this requirement is also met by the drum selected according to the above principle. However, the surface of the roller may also include a second part having a surface tension lower than that of the first part. This is particularly helpful for proper separation of the filaments or tows from the surface of the drum, which further avoids unwanted effects on the filaments or tows, such as filament breakage. Therefore, the drum according to the present invention may include a second surface portion, which enables the filaments or tows to be better removed or separated from the surface of the drum without harmful effects on the filaments or tows. According to the present invention, this is ensured by providing suitable separation portions on the surface of the roller, preferably with regular intervals, wherein the portions are characterized in that they exhibit a surface tension lower than the surface tension of the first portion. Preferably, the second parts exhibit a surface tension that is at least 5% lower than the surface tension of the first part, more preferably at least 10%, and still more preferably at least 25%. In an implementation aspect, the difference is at least 10 mN/m, preferably at least 25 mN/m. It is obvious from the above that the surface tension of the second part can in principle be covered by the range defined for the first part. However, as long as the surface tension of the second part is lower than the surface tension of the first part, the two-part types can be clearly defined, and the two-surface part types can be distinguished. This is more obvious if the second part has another structure (surface structure, such as roughness or a different three-dimensional structure, such as depressions or creases) or is made of a different material. However, as long as the required lower surface tension is provided, the second part can be used for the desired purpose (helping the separation of the filament/yarn from the drum), because during use, these differences are sufficient (even if the absolute value is still Within the surface tension range defined for the first part).

According to the present invention, various methods can be used to provide such a separated portion. One possibility is to provide creases or grooves on the surface of the drum, preferably extending parallel to the axis of the drum. By providing such creases or grooves, the (theoretical) surface of the roller becomes different from the main high surface tension material used for the roller (which satisfies the requirements for good adhesion by simply providing a non-existent surface (ie, air) The above requirements). Such a "non-existent" surface is regarded as a material with low surface tension in the context of the present invention. During filament processing, the folds or grooves can also be filled with water, which also provides surface tension within the required range.

Another option is to reduce the surface roughness, because this will also cause the surface tension of the separated part to fall within the above range.

In addition, it is also possible to provide a material (preferably a synthetic polymer) with a surface tension within the above range to fill the creases or grooves provided on the surface of the roller. In a similar way, that is, by using a low surface tension material, preferably a synthetic polymer, it is also possible to provide coated portions on the surface of the drum, which coated portions provide surface tension in the desired range. One way to ensure that the coating functions in the desired manner is to fill the microcracks or microcracks in the surface of the roller material. However, the present invention also envisages providing such a coating on the microscopic surface area of the drum surface.

In the case of providing pleats or grooves, it is preferable that these pleats or grooves have a width in the range of 0.5 to 5 mm, preferably 1.5 to 2.5 mm (that is, a dimension perpendicular to the axis of the drum). The distance between two such grooves or creases may be in the range of 2 to 25 mm, preferably 2.5 to 10 mm, more preferably 3 to 4.5 mm. This size can also be used in consideration of the coating on the surface of the drum to create separation points, for example by synthetic polymers.

Since the generation of the separated part (ie, the second part according to the present invention) requires additional manufacturing steps, such as a surface modification process and/or a coating process, it is preferable that most of the surface of the drum is made of the first part. Since these parts are usually made of the main material used in the manufacture of the surface of the roller, it is often commercially beneficial if the surface parts constitute the majority of the surface of the roller. The typical proportion of the first part relative to the surface of the whole drum is 40 to 95%, preferably 50 to 80%, inclusive of 60 to 70%. In the implementation aspect, the surface of the roller consists of only the first part.

The creases, grooves, and microcracks or microcracks to be provided on the surface of the roller can be prepared by appropriate surface treatment methods such as etching procedures according to methods known to those skilled in the art. Likewise, a skilled person can coat the surface of the drum with a synthetic polymer to produce a coating that provides separate parts. Similarly, providing a part with reduced surface roughness is also within the usual practice of the skilled person.

Suitable materials for the high surface tension part of the drum surface are especially metals, especially iron-based materials, stainless steel, chromium, aluminum, etc. However, it has been found that other materials, such as ceramics, can also be used as long as the surface tension requirements are met. If it is not only provided with creases or grooves, the material suitable for providing the separation part is usually a synthetic polymer, such as PVC, PA, polyolefin, PTFE, PET, PMMA, etc. In order to promote the production of the roller surface proposed by the present invention, it is better to use a thermoplastic polymer.

Surprisingly, it has been found that by following the above guidelines, in other words, by ensuring that the surface tension of the main material used on the surface of the drum is within the above range, and at the same time providing a separate part that also meets the surface tension of the above requirements. It can easily ensure that the filaments or tows are properly transported around the drum during the manufacture of lyocell filaments without causing unwanted effects such as slippage, contact of the filaments or tows, and filament breakage.

Therefore, the present invention proposes to use a drum as defined and described herein during the manufacture of lyocell filaments, especially as a guide drum for winding filaments or tows after coagulation, but also for liquid removal, washing or Any subsequent rollers used during the drying operation.

A chrome-plated steel drum is used to manufacture lyocell filaments. The surface tension of the roller is measured according to the following method. Using a drum with a surface tension of about 37 mN/m (the surface tension of the drum is about 0.5 times the surface tension of the washing liquid), even during high-speed filament manufacturing, high-quality lyocell yarns can be manufactured. There are no problems related to filament breakage. Similar results were obtained using roller surfaces with surface tensions of approximately 44, 56, 93, and 185 mN/m (ie, factors of 0.6, 0.75, 1.3, and 2.4). The surface tension values mentioned in this article are based on the method of Owens-Wendt-Rabel-Kaelble, using the surface energy measurement device from Krüss (DSA10HS), using the corresponding software (DSA10HSAJ1H "Drop shape Ananlysis System Serial Number 20012303 (Q161F800 INR.59028) ) Measurement. Use the following three standard measurements, using at least 1 droplet (30 measurement results per droplet) measurement results (60 seconds after the droplet deposition) to calculate the surface tension value: -HPLC water -Ethylene glycol used for analysis (density> 99.5%, available from Merck: K42538921 133 1.09621.1000) -Diiodomethane (purity> 99%, after stabilization, it can be obtained from Acros organics: 169830250 A0390451, for example)

Claims (15)

A drum suitable for use during the manufacture of lyocell filaments, wherein the surface of the drum contains a first part showing surface tension so that depending on the liquid adhering to the filament or yarn, one of the following conditions is satisfied By: a) If the surface tension of the liquid is 45 mN/m or higher, the surface tension of the first part is 0.25 to 3.5 times the surface tension of the liquid, preferably 0.35 to 2.5, more preferably 0.4 to 0.8 Times the range; or b) If the surface tension of the liquid is less than 45 mN/m, the surface tension of the first part is 0.5 to 10 times, preferably 0.8 to 2.5, more preferably 1 to 2 times the surface tension of the liquid Scope. A method of selecting a roller for process steps during the manufacture of lyocell filaments, characterized in that the roller is selected so that the surface of the roller contains a first part showing surface tension, so that it depends on adhesion to the filament or yarn The liquid that meets one of the following conditions: a) If the surface tension of the liquid is 45 mN/M or higher, the surface tension of the first part is 0.25 to 3.5 times the surface tension of the liquid, preferably 0.35 to 2.5, more preferably 0.4 to 0.8 Times the range; or b) If the surface tension of the liquid is less than 45 mN/m, the surface tension of the first part is 0.5 to 10 times, preferably 0.8 to 2.5, more preferably 1 to 2 times the surface tension of the liquid Scope. Such as the roller of claim 1 or the method of claim 2, wherein the surface tension of the first parts is such that the following conditions are satisfied: the surface tension of the first parts of condition a) is 1 to the surface tension of the liquid The range of 1.75 times; the surface tension of the first parts of condition b) is in the range of 0.9 to 5 times the surface tension of the liquid. The roller of claim 1 or 3 or the method of claim 2 or 3, wherein the surface of the roller includes a second part having a lower surface tension than the first parts. The drum or method according to any one of the preceding claims, wherein the first parts are made of metal, preferably made of chrome-plated steel. Such as the roller or method of any one of claim 4 or 5, wherein the second part is made of synthetic polymer. The roller or method of any one of claim 4 or 5, wherein the second parts are creases or grooves. The roller or method according to any one of the preceding claims, wherein the surface of the roller only includes a first part, or wherein the first and second parts extend substantially parallel along the roller axis. The roller or method according to any one of claims 4 to 8, wherein the second parts show a width of 0.5 to 5 mm, preferably 1.5 to 2.5 mm. The roller or method according to any one of claims 4 to 9, wherein the second parts are separated by 2 to 25 mm, preferably 3 to 4.5 mm. The roller or method according to any one of the preceding claims, wherein the first parts account for 40 to 95% of the surface area of the roller surface. A use of the roller according to any one of the preceding claims, wherein the roller is used during the manufacture of lyocell filaments. Such as the use of claim 12, wherein the roller is used as a guidance roller for lyocell filaments or tows after leaving the coagulation bath to take up the lyocell filaments or tows . Such as the use of claim 12, wherein the drum is used during liquid removal and/or washing steps. Such as the use of claim 12, wherein the roller is used during the application of additional substances to the filament.