RU2127775C1 - Method of manufacturing cellulose fibers with reduced tendency toward fibrillation - Google Patents

Abstract

FIELD: textile industry. SUBSTANCE: solution of cellulose in tertiary amine oxide is spun into fibers. Freshly spun fibers are brought into contact with textile-auxiliary substance having two reactive groups in alkaline medium. Textile- auxiliary substance can be either a dye or a colorless substance. Afterwards, fibers are washed with buffer solution and can undergo heat treatment caused by electromagnetic waves or microwaves. EFFECT: several-fold reduced tendency of fibers to fibrillation with no sacrifice of their physico-chemical properties. 8 cl, 4 tbl, 19 ex

Description

 The invention relates to a method for producing cellulose fiber with a reduced tendency to fibrillate.

 As an alternative to the viscose method, in recent years a number of methods have been described in which cellulose is dissolved without formation of a derivative in an organic solvent, combinations of an organic solvent with an inorganic salt, or in aqueous solutions of salts. The cellulosic fiber obtained from such solutions is called lyocell in BISFA (The International Bureau for the Standardization of man made Fiber). Lyocell, as defined by BISFA, is cellulose fiber obtained by spinning from an organic solvent. By "organic solvent", as defined by BISFA, is meant a mixture of an organic chemical and water. "Spinning in solution" means dissolution and spinning without formation of derivatives. However, to date, only one way to obtain cellulose fiber type lyocell has found application in industry. In this method, a tertiary amine oxide, in particular N-methylmorpholine-N-oxide (NMMO), is used as a solvent. Such a method is described, for example, in US Pat. No. 4,246,221; it allows you to get fiber, characterized by high strength, high modulus of moisture and high strength in the loop.

 However, the suitability of products of a flat shape, for example, fabrics made from the specified fiber, is greatly limited due to the pronounced tendency of this fiber to fibrillate in the wet state. By fibrillation is meant splitting of the wet fiber in the longitudinal direction under mechanical stress in the wet state, as a result of which the fiber becomes fleecy. A fabric made from this fiber and dyed loses much after several washings the color intensity. In addition, light streaks appear on shabby and wrinkled edges. Preferably, the cause of fibrillation is that the fiber consists of fibrils located in the direction of the fiber, between which there is only a small degree of polymer network formation.

 WO 92/14871 describes a method for producing fiber with a reduced tendency to fibrillate. This is achieved by the fact that all baths with which the freshly spun fiber is in contact before the first drying have a maximum pH of 8.5.

 WO 92/07124 also describes a method for producing fibers with a reduced tendency to fibrillate, in which freshly spun, i.e. fiber not yet dried is treated with a cationic polymer. As such a polymer, a polymer with imidazole and acetidine groups is used. In addition, treatment with an emulsifiable polymer, for example, polyethylene or polyvinyl acetate, can also be carried out, or glyoxal crosslinking can also be carried out.

 A report made by S. Mortimer at the 1993 CELLUCON conference in Lund, Sweden, mentioned that the tendency to fibrillate increases with increasing stretching.

 The objective of the invention is to provide a method that can be carried out in a simple way and allows you to get cellulose fiber type lyocell with a reduced tendency to fibrillation.

 According to the invention, a method for producing a cellulose fiber with a reduced tendency to fibrillate consists in contacting a freshly spun, not yet dried fiber with a textile auxiliary substance containing at least two reactive groups and washed with an aqueous buffer solution.

 As textile auxiliary substances, dyes having two reactive groups, in particular, have proven themselves well. Colorless textile substances, i.e. those that do not absorb visible light.

 Textile auxiliaries having one or two vinyl sulfone groups as reactive groups are preferably used according to the invention.

 A suitable embodiment of the method according to the invention is characterized in that the freshly spun fibers are contacted with a textile auxiliary substance in an alkaline environment.

 It turned out that the tendency to fibrillate is especially reduced when the alkaline environment is created by alkaline carbonate and alkaline hydroxide.

 A further preferred embodiment of the method according to the invention is that the fiber in contact with the textile excipient is heat treated. Heat treatment dramatically reduces the duration of the impregnation.

 European application EP-A-0538977, published April 28, 1993, describes the heat treatment of dye impregnated cellulose fibers. However, it turned out that heating the fiber impregnated with the textile auxiliary material with hot air can shorten the impregnation time, but there is a danger that the fiber heats up unevenly. So, for example, the fiber of the dried fiber bundle located outside may already be partially dry, while the fiber inside has not yet reached the required temperature. This adversely affects the quality of the produced fibers.

 It was found that this disadvantage arising from simple heat treatment can be eliminated if the fiber is irradiated with electromagnetic waves, in particular microwaves. When irradiated with microwaves, the fiber, on the one hand, heats up evenly, and, on the other hand, premature drying of the fiber can be eliminated, since irradiation with electromagnetic waves makes it possible to weld a fiber bundle, for example, in a plastic sheath, and to expose it to the electromagnetic field when brewed.

 The above advantages are also provided if the fiber, for example, in the form of an even product of a flat shape, is located on a conveyor belt and transported along a narrow channel in which it is exposed to electromagnetic waves. This channel can be made in such a way that there is only a small air space above the fibers, as a result of which partial drying of the external fiber can be avoided. At the same time, this option of fixing the textile auxiliary substance also opens up the technically simple possibility of industrial production.

 Accordingly, the invention further relates to a method for producing cellulose fiber with a reduced tendency to fibrillate, in which a solution of cellulose in a tertiary amine oxide is spun into a fiber and freshly spun fiber is contacted with a textile auxiliary material having at least two reactive groups, and is heat treated, and the method characterized in that the heat treatment is carried out by irradiation with electromagnetic waves.

 And according to this embodiment, the method according to the invention preferably uses a textile auxiliary substance having vinyl sulfone groups as reactive groups and which is preferably a dye. However, textile auxiliary colorless substances, that is, those that do not absorb visible light, can also be used.

 A further preferred embodiment of the method according to the invention is that the heat treatment is carried out using microwaves.

 The invention is explained in more detail using the following examples. All data in% should be understood as weight%.

Cellulose Fiber Production
According to the method described in European application EP-A-0356419, a solution of cellulose in NMMO was prepared, which was extruded through a die. The elementary fiber thus obtained entered through an air section into an aqueous precipitation bath in which cellulose coagulates. The fiber obtained in the precipitation bath was washed and had a titer of 1.72 dtex. The washed fiber was used for the examples described below and is a fiber, which in this description in these claims is referred to as freshly spun, not yet dried fiber.

 1) Processing textile auxiliary substances without subsequent heat treatment.

A) General method. 1 g of the fiber obtained by the above method was impregnated in 190 ml of an aqueous solution (bath) containing a textile auxiliary substance having two reactive groups, and Na ₂ SO ₄ , for 30 minutes at 40 ^° C. Then, to fix the textile auxiliary substances were added NaOH (3%), Na ₂ CO ₃ (4%) or a mixture of NaOH, Na ₂ CO ₃ (4% Na ₂ CO ₃ and 0.2 g / l NaOH).

After a further 60 minutes at 40 ^° C., the fiber was washed several times to remove the textile auxiliary material loose on the fiber. The washed fiber was then treated with an aqueous buffer for 30 minutes and then washed again with water (15 minutes) and dried at 60 ^° C. After that, the fiber was examined for fibrillation tendency and other data.

Fibrillation score
The friction of the fibers against each other during washing or finishing in the wet state was modeled using the following test: 8 fibers with a length of 20 mm with 4 ml of water were placed in a 20 ml sample bottle and vibrated for 9 hours in a laboratory vibration device type RO-10 company Gerhardt, Bonn (Germany) to a scale of 12. The fiber fibrillation behavior was then evaluated under a microscope by counting the number of fibrils per 0.276 mm fiber length.

Other fiber characteristics
Fiber strength and elongation were tested according to the requirements of BISFA "Internationally agreed methods for testing viscose, modal, cupro, lyocell, acetat and triacetate staple fibers and tows", 1993 edition.

 B) Examples. According to the method described above, the fiber was treated with Remazol Black B and Remazol Red RB dye as a textile auxiliary substance (manufacturer: Hoechst AG). The Remazol Black B dye has two vinyl sulfone groups and the Remazol Red RB dye has one vinyl sulfone group and one monochlorothiazine group. The solution contained 3% Remazol Black B or 0.5% Remazol Red RB. In each example, the pH of the solution was 4.6. The aqueous buffer used was an aqueous solution containing 3% acetic acid and 7% sodium acetate. The pH of this solution was 4.6. After treatment with a buffer solution, the fibers were washed with water for 15 minutes and then examined. Table 1a shows the fixing agent used, fibrillation (number of fibrils), titer (dtex), fiber strength (cN / tex) and fiber elongation (%). Examples 1, 2, and 3 were carried out with Remazol Red RB. Table 1b shows the results of comparative experiments conducted without dye.

A comparison of the results of Tables 1a and 1b shows that the textile auxiliary agent, in this case, Remazol Black B and Remazol Red RB dyes, sharply reduces the tendency of the fiber to fibrillate and that the combination of NaOH + Na ₂ CO ₃ used to fix the textile auxiliary substance, also significantly reduces the tendency to fibrillate.

 It turned out that the above results were also obtained using other textile auxiliary substances having two reactive groups, Remazol Black B and Remazol Red RB thus replace other textile auxiliary substances that also have at least two reactive groups.

 2) Processing textile auxiliary substances, followed by heat treatment.

Accordingly, 1 g of the fiber obtained by the above method was impregnated in 190 ml of a solution containing 0.2% Remazol Black B, 2% Na ₂ CO ₃ , 0.2% NaOH, pH 11.5, 3 times for 30 seconds, and the fiber after each impregnation was squeezed. Then, each sample was subjected to heat treatment 2 times for 40 seconds in an oven with air circulation at 180 ^° C. After that, each sample subjected to heat treatment was treated for 30 minutes with the above acetate buffer solution (pH 4.6), washed for 15 minutes with water, and dried at 60 ^o C and was investigated. The results are shown in table. 2, where Example 10 was a control (for Example 10, Example 9 was repeated, however, no textile auxiliary substance was used).

 From the table. 2 it follows that the heat treatment of a fiber impregnated with a textile auxiliary substance sharply reduces the time of impregnation and that, despite this, the tendency to fibrillate is reduced.

 Similar dye results were obtained with Remazol Red RB.

 3. Processing with textile auxiliary substances, followed by irradiation with microwaves.

10 g of the fiber obtained by the above method was impregnated in 900 ml of a solution (10% Remazol Black B, 10% Na ₂ SO ₄ , 8% Na ₂ CO ₃ ; the pH was adjusted to 11.5 with NaOH) for 9 minutes. Then the fiber was squeezed and divided into 2 identical large parts (examples 12, 13). Example 11 served as a control and showed the properties of the fiber, not treated with a textile auxiliary substance. For examples 12 and 13, after the solution was impregnated, the fiber was squeezed out and heated 180 seconds to 180 ^° C (example 12) or irradiated for 50 seconds with 90 W microwaves (example 13). Then the fiber was treated for 30 minutes in the above acetate buffer solution at pH 4.6, washed for 15 minutes with water and dried at 60 ^o C. The test results are shown in table. 3.

 From the table. 3 that microwave irradiation shortens the heating time and that the tendency to fibrillate decreases further. Similar good results in reducing the tendency to fibrillate were obtained when other textile excipients with at least two reactive groups were used instead of Remazol Black B. In particular, it turned out that the beneficial effect on the tendency to fibrillate is expressed as strongly as with glyoxal. Further, it turned out that the above-mentioned favorable effect, which gives irradiation with microwaves, is also observed with glyoxal and other dialdehydes, as can be seen from the following example.

2 g of the fiber obtained by the method described in Section 1 was soaked twice in 3 minutes in 140 ml of a solution containing 2% glyoxal and 0.66% crosslinking catalyst (e.g. Condensol FB, a mixture of ZnCl ₂ and MgCl ₂ , manufacturer: BASF ) Then the solution was squeezed out, the fiber was divided into 2 parts (examples 15, 16). Example 14 served as a control, for example 15, the fiber was treated for 10 min in an oven with air circulation at 100 ^° C, and for example 16, the fiber was exposed to a 500 W microwave twice in 60 seconds. The fibrillation results are shown below in table. 4.

 The above described action was repeated, however, glutardialdehyde (3.4%) was used instead of glyoxal. The results of fibrillation of the obtained fiber are also shown in table. 4 (examples 17, 18 and 19 correspond to examples 14, 15 or 16).

Claims (7)

 1. A method of producing cellulose fibers with a reduced tendency to fibrillate, in which a solution of cellulose in tertiary amine oxide is spun into fibers, characterized in that the freshly spun fibers are contacted with a textile auxiliary material having at least two reactive groups in a brush medium and washed with aqueous buffer solution.  2. The method according to claim 1, characterized in that a dye or a colorless substance is used as a textile auxiliary substance.  3. The method according to claim 1 or 2, characterized in that they use a textile auxiliary substance having at least one vinyl sulfone group as a reactive group.  4. The method according to claim 1, characterized in that the alkaline medium is created by alkaline carbonate and alkaline hydroxide.  5. The method according to one or more of claims 1 to 4, characterized in that the fiber in contact with the textile auxiliary substance is subjected to heat treatment.  6. The method according to claim 5, characterized in that the heat treatment of the fibers is carried out by irradiation with electromagnetic waves.  7. The method according to claim 6, characterized in that the heat treatment is carried out using microwaves.

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