CN1165544A - Cellulose Fiber - Google Patents

Abstract

This invention relates to a method for manufacturing cellulose fibers by the amine oxide process, in which a solution of cellulose in an aqueous tertiary amine oxide is spun into fibers and the fibers are contacted with a crosslinking agent. The method is characterized by using a sulfonium compound of formula (I) and/or a sulfonium compound of formula (II) as the crosslinking agent, wherein in formula (I), _R1 is _CH2CH2Z , _alkyl , aryl, substituted alkyl, or heterocyclic, Z is a halogen, sulfate group, thiosulfate group, phosphate group, or hydroxyl group, and ^Y- is an anion; in formula (II), _OW is a polyacid residue in the form of a salt or acid, and _R2 is _CH2CH2OW , alkyl, aryl, substituted alkyl, or heterocyclic.

Description

Cellulose Fiber

The present invention relates to a novel cellulose fiber and a method of making the cellulose fiber.

In recent years, instead of the viscose method, a series of methods have been reported in which cellulose is dissolved in an organic solvent, a mixture of an organic solvent and an inorganic salt, or an aqueous solution of a salt without generating a derivative. The cellulose fibers produced from this solution received the generic name Lyocell from BISFA (International Bureau for the Standardization of Man-Made Fibres). BISFA defines such a cellulose fiber as Lyocell, which is a fiber obtained from an organic solvent by spinning. By "organic solvent" BISFA understands a mixture of organic chemicals and water.

So far only one method of manufacturing cellulose fibers under the generic name Lyocell has been industrialized. In this process, hereinafter referred to as the amine oxide method, tertiary amine oxides are used as solvents, in particular N-methylmorpholine-N-oxide (NMMO). This method is described, for example, in US-A-4,246,221, which provides fibers characterized by high tenacity, high wet modulus and high interlocking strength.

The characteristic of Lyocell fiber is that it has a prominent tendency to oxidize in wet state. Fibrillation is understood to mean the splitting of wet fibers in the wet state under mechanical stress along their length, whereby the fibers acquire a hair-like, fur-like appearance. The cause of the fibrillation is conceivable: the fiber is composed of fibrils aligned along the fiber direction, with only a slight degree of crosslinking between the fibrils.

WO 92/14871 describes a method for producing fibers with a small fibrillation tendency. This is achieved by adjusting the pH of all baths with which the freshly spun fibers come into contact prior to the first drying to a maximum of 8.5.

WO 92/07124 likewise describes a method for producing fibers with a tendency to microfibrillation, in which freshly spun fibers, i.e. not yet dried fibers, are treated with a cationizable polymer. Polymers of this type are polymers containing imidazole- and acridine groups. In addition, it can be treated with emulsifiable polymers, such as polyethylene or polyvinyl acetate, or cross-linked with glyoxal.

In the report made by S. Mortimer at the CELLUCON meeting held in Lund, Sweden in 1993, it was mentioned that the tendency of fibrillation increases with the increase of stretching.

Several methods have been published to reduce the fibrillation propensity of Lyocell fibers:

It is known, for example, from WO 95/02082 of the applicant that fibrillation can be reduced by certain combinations of spinning parameters.

It is also known that the fibrillation properties of Lyocell fibers can be improved by chemical crosslinking, for example EP-A-0538977 describes the crosslinking of Lyocell fibers with chemical reagents that can react with cellulose, which can be done in the undried state, i.e. It can be carried out in fiber manufacturing, but also in the dry state, that is, basically in fabric finishing.

In the above-mentioned patent application EP-A-0538977, the cross-linking agents introduced by way of example have halogen-substituted nitrogen-containing ring structures, as cross-linking capable groups, which are able to react with the hydroxyl groups of cellulose under basic conditions. In addition, compounds having vinylsulfon groups or their precursors have also been reported. These compounds also essentially only react when a base is added or the base required as a neutralizing agent to cleave the acid is added.

One of the disadvantages is that during the reaction of halogenated nitrogen-containing rings or vinyl sulfones or their precursors, salts are formed which must subsequently be washed out of the fibers, and in addition excess and unreacted cellulose fibers Residual chemicals must also be washed out. This means that a further post-treatment step is required in the continuous fiber production process, which results in additional capital and operating costs and also creates sewage problems.

A similar process is suggested in WO 94/24343 of the applicant for the crosslinking of Lyocell fibers to prevent fibrillation, where it is mentioned that it is particularly advantageous to use a basic buffer and to irradiate with electromagnetic waves.

It is described in WO 94/20656 that the reduction of fibrillation of Lyocell fibers by crosslinking with conventional crosslinking chemicals generally used to improve the crease angle of cellulosic textiles, if crosslinked in a flexible, linear polymer In the presence of both, the dyeability of the fiber will not be reduced. Basically conventional N-methylol resins (with low methanol content) and conventional acidic catalysts are used. It is also shown that the method can be successfully applied to fibers that have been dried as well as fibers that have never been dried.

From US-A-3,251,642 it is known to treat fibers obtained from regenerated cellulose, such as viscose or cotton, with sulfatoalkyl-sulfonium salts, especially when treating fabrics of these fibers , resulting in improved wet- and dry crease angle recovery properties due to crosslinking of the regenerated cellulose. These salts are therefore used as so-called wrinkle-free finishes. In addition, it is also known that under strongly alkaline conditions, cotton and sulfated alkyl-sulfonium salts, especially the internal salts of disodium-three (β-sulfatoethyl) sulfonium (this internal salt is hereinafter referred to as trisSS) started at room temperature.

Treatment of reactive NH-, OH- - or SH-group polymers. The crosslinking of cellulosic textile materials with trisSS is described in US-A-3,480,382 and US-A-3,542,503. It is also known from GB-A-1,082,600 to use trisSS in combination with dyes to crosslink cellulose during the dyeing process.

In the patent documents cited above, dried substrates such as fibers, fabrics, films and paper are impregnated with a 5-25% aqueous solution of a cross-linking agent and a 4-35% aqueous solution of an alkali, wherein first the cross-linking agent is followed by the alkali , or vice versa first with a base and then with a cross-linking agent.

When using a latent basic compound, such as an alkali metal bicarbonate, the crosslinking agent can be applied from a bath together with the base, followed by a high temperature treatment to effect the crosslinking. In addition, intermediate drying may be performed between the crosslinking treatment and the treatment with alkali. As basic compounds, alkali metal hydroxides, alkali metal carbonates and bicarbonates, quaternary ammonium bases such as trimethylammonium hydroxide are used. The reaction time is 10 minutes at room temperature and shorter residence times at higher temperatures, for example 3 minutes at 150°C. After the reaction is completed, the substrate must be washed free of alkali.

In the prior art, no method is known to control the fibrillation tendency of fibers produced by the amine oxide method. It is therefore the object of the present invention to provide a method for producing Lyocell fibers with which fibers having a predetermined tendency to fibrillation can be produced.

其中OW是盐或酸形式的多元酸残基，R₂是CH₂CH₂OW、烷基，特别是C_1-4烷基，芳基、取代的烷基或杂环。In the method of the present invention for producing cellulose fibers by the amine oxide method, a solution of cellulose in an aqueous amine oxide is spun into fibers, and the fibers are brought into contact with a crosslinking agent, characterized in that as the crosslinking agent The sulfonium compound of formula (I): wherein R ₁ is CH ₂ CH ₂ Z, alkyl, especially C _1-4 alkyl, aryl, substituted alkyl or heterocycle, Z is halogen, Sulfato, thiosulfate A group (Thiosulfato), a phosphate group (Phosphato) or a hydroxyl group, Y- is an anion, and/or a sulfonium compound of formula (II),

wherein OW is a polyacid residue in salt or acid form, R ₂ is CH ₂ CH ₂ OW, alkyl, especially C _1-4 alkyl, aryl, substituted alkyl or heterocycle.

It has surprisingly been found that the treatment of fibers produced by the amine oxide process with the aforementioned sulfonium compounds opens the way for the fibrillation tendency of the fibers not only to be reduced but also to be controlled as desired.

In the process of the present invention, as the sulfonium compound of formula (II) preferably the inner salt of dialkali metal-tri-(β-sulfatoethyl)sulfonium, in particular disodium-tri-(β-sulfatoethyl)sulfonium Inner salt of ethyl) sulfonium.

According to the method of the present invention, the fibers can be contacted with the crosslinking agent either in the never-dried state or in the dried state, but preferably in the never-dried state, for example freshly spun The state is in contact with the cross-linking agent.

The fibers are preferably treated with an alkali prior to contacting with the crosslinking agent, wherein the fibers may be dried prior to the alkali treatment.

In a particularly advantageous embodiment of the method of the invention, the fibers are treated with alkali and simultaneously contacted with a crosslinking agent, wherein the molar ratio of alkali to crosslinking agent is essentially 3:1 (alkali:crosslinking agent). The fibers are then dried. It has been shown that in this embodiment of the method of the invention the fibers do not need to be washed. This is an advantage insofar as it saves an operating step in the production method.

Preferably, the fibers are brought into contact with an aqueous solution of trisSS having a concentration of 0.3-25% by mass, preferably 0.5-5% by mass. In the aqueous solution, based on trisSS, the amount of alkali is 0.8-100 moles, preferably 2.5-3.5 moles. As bases, in particular alkali metal hydroxides, alkali metal carbonates and bicarbonates, quaternary ammonium bases and polymeric amines are used. It has also been found that according to the invention it is also possible to add buffer solutions in the pH range from 5-12, preferably from 7-9.

If the added base is a potentially basic compound, such as bicarbonate, no washing is necessary.

The invention also relates to cellulose fibers with a predetermined tendency to fibrillation, obtainable by the process of the invention.

其中，R₁，Z和Y^-的意义同上，其中，OW和R₂具有在权利要求1所述的意义。The invention also relates to the use of sulfonium compounds of the formula (I) and/or of the formula (II) for the treatment of fibers produced by the amine oxide process and yarns and fabrics consisting of fibers produced by the amine oxide process ,

Wherein, R ₁ , Z and Y ^- have the same meaning as above, Wherein, OW and R ₂ have the meaning described in claim 1.

The invention also relates to the treatment of fibers produced by the amine oxide process and yarns and fabrics consisting of fibers produced by the amine oxide process with an aqueous solution of an inner salt of a dialkali metal-tris-(β-sulfatoethyl)sulfonium in the application.

Particularly suitable is the treatment of fibers produced by the amine oxide process and fibers consisting of fibers produced by the amine oxide process with an aqueous solution containing an alkali and an internal salt of a dialkali metal-tris-(β-sulfatoethyl)sulfonium Yarns and fabrics wherein the molar ratio of base to crosslinker is substantially 3:1 (base:crosslinker).

Freshly spun, never-dried fiber bundles or never-dried loose fibers can be impregnated with trisSS solution first, and then impregnated with lye after pressing to a moisture content of 100 to 150%, wherein the sequence of treatment is also Can be reversed. After about 10 minutes at room temperature, it can be washed and dried.

In addition, it is also possible to impregnate the fibers first with a trisSS solution, press to a content of 100-150%, dry the fibers and treat them with alkali directly thereafter, or at a later time.

Furthermore, the process according to the invention can be carried out in one step, wherein the fibers are simultaneously treated in one step with a solution of trisSS and a small amount of alkali. It was surprisingly found that, for the one-step process, not only potentially basic compounds, such as alkali metal bicarbonates, but also rather low concentrations of base can be used.

In the one-step process, a subsequent temperature treatment of the impregnated fibers is required. Temperature treatment can be achieved by drying at a temperature of at least 60°C. If the molar ratio of base to trisSS is not greater than 3:1, no subsequent wash is required.

Facts have shown that using the above-mentioned sulfonium compounds can reduce or even eliminate fibrillation as required through a series of reaction conditions (concentration of crosslinking agent, amount and type of alkali).

It has also been shown that the treatment with crosslinking agents according to the invention can be carried out before, simultaneously or after the dyeing process. For example, the abovementioned sulfonium compounds can be added to basic dyebaths.

The invention is further explained by the following examples. For the manufacture of TrisSS reference is made to Belgian patent applications No. 627204 and No. 620775.

Evaluation of Fibrillation

In order to evaluate the tendency of fibrillation, put 8 fiber samples each with a length of 20 mm and 4 ml of water in a 20 ml glass bottle, and carry out 9 hours and 12 hours with a laboratory oscillator model RO-10 produced by Gerhardt Company in Bonn, Germany. stage oscillation. The fibrillation properties of the fibers were then evaluated by counting the number of fibrils per 0.276 mm fiber length under a microscope.

According to this measurement, a conventional cellulose fiber with the genus name Lyocell has about 50 fibrils in a fiber length of 0.276 mm. Conventional cellulose fibers with the generic name Modal, which are known to have no tendency to fibrillate, have, by way of comparison, 1 to 2 fibrils.

Example 1 - Scenario A

1 g of freshly spun Lyocell fibers in the form of loose fibers in 100 ml of trisSS aqueous solution for 3 minutes at room temperature, pressed to a water content of 140%, and then immersed in 100 ml of caustic soda solution for 10 minutes at room temperature . The fibers were then washed with 3% acetic acid and water until alkali-free, and dried overnight at 60°C.

The fiber was then studied for its tendency to fibrillate according to the test described above. The results are listed in Table 1 below.

Example - Scenario B

1 g of freshly spun Lyocell fiber that has not been dried is immersed in 100 ml trisSS aqueous solution at room temperature for 3 minutes in the form of loose fibers, dried at 60 ° C for 2 hours, and then immersed in 100 ml caustic soda aqueous solution at room temperature for 10 minutes. Then the fiber was washed with 3% acetic acid and water until alkali-free, and dried overnight at 60°C.

The fiber was then studied for its tendency to fibrillate according to the test described above. The results are listed in Table 1 below.

In Table 1 the concentrations of trisSS are expressed in g/l. The concentration of caustic soda is expressed in g NaOH/l.

Table 1 Instance Number TrisSS Concentration Caustic Soda Concentration Scheme Fibril Number

1 - - - - 50

2 1 0.16 A 50

3 50 11.6 A 20

4 50 116 B 10 5 10 2.22 B 456 10 4.44 B 457 10 44.4 B 178 10 88.8 B 6

Examples 5-8 show that as the concentration of caustic soda increases, the number of fibrils decreases and the resulting fibers are less fibrillated. Therefore, the use of trisSS according to the present invention can control the fibrillation tendency of Lyocell fibers through the alkali concentration. When a large amount of alkali is used, it is of course necessary to wash the fibers to be alkali-free.

The same result was obtained with fibers in skein form.

Example 2 - Scenarios C1, C2, D1 and D2

Immerse 1g of freshly spun and not yet dried Lyocell fibers in 100ml trisSS aqueous solution and alkali solution [TBAH (tetrabutylammonium hydroxide), NaOH or KHCO ₃ ] in the form of loose fibers for 5 minutes, and press to a water content of 140 %. The fibers are then subjected to the following treatments:

Dry overnight at 60°C, wash and re-dry (=Scheme C1); or

Dry overnight at 60°C without washing (=Scheme C2); or

Dry at 100°C for 10 minutes, wash and re-dry (=recipe D1); or

Dry at 100° C. for 10 minutes without washing (=Variant D2).

The fiber was then studied for its tendency to fibrillate according to the test described above. The results are listed in Table 2. In Table 2, trisSS concentrations are expressed in g/l. The alkali concentration is expressed in g/l.

Table 2 Instance number TrisSS concentration Alkaline concentration Scheme Fibril number

1 - - - - - 50

9 15 0.34 TBAH D1 50

10 15 0.34 TBAH D2 50

11 15 25.7 TBAH C1 20

12 15 25.7 TBAH C2 20

13 15 25.7 TBAH D1 20

14 15 25.7 TBAH D2 25

15 15 4.5 NaOH C1 sporadic 16 15 4.5 NaOH C2 017 15 4.4 NaOH C1 sporadic 18 15 4.4 NaOH C2 sporadic 19 15 3.5 NaOH C1 3320 15 3.5 NaOH C2 3521 15 3.5 NaOH D1 2OH 3 322 10 2.7 NaOH D1 024 10 2.7 NaOH D2 025 15 79.0 KHCO ₃ C1 2026 15 79.0 KHCO ₃ C2 3527 15 79.0 KHCO ₃ D1 2028 15 79.0 KHCO ₃ D2 35

Examples 9 to 24 show the effect of alkali concentration on the reduction of fibrillation. When the molar ratio of alkali to crosslinking agent is 3:1, the use of NaOH as the alkali component can already make fibrillation disappear (see examples 23 and 24 ), and there is no need to use a larger amount of NaOH (see examples 15-18).

At a molar ratio of 2.7:1 (Examples 10-22) fibrillation was reduced by 40%.

Fibrillation was reduced by 50% when TBAOH was used at a ratio of 3:1 to crosslinker.

Furthermore, it is apparent from the examples that no washing is necessary when using small amounts of base (eg, 2.5 to 3.5 moles of base to 1 mole of crosslinker).

The same result was obtained with fibers in the form of skeins.

It has also been shown that fabric parameters such as strength, elongation, etc. are substantially not impaired when fibers are treated with the above-mentioned sulfonium compounds according to the invention.

Claims (12)

1. A method for producing cellulose fibers by the amine oxide method, in which a solution of cellulose in an aqueous tertiary amine oxide is spun into fibers, and the fibers are contacted with a crosslinking agent, characterized in that as crosslinking agent The coupling agent adopts the sulfonium compound of chemical formula (I) and/or the sulfonium compound of chemical formula (II), In formula (I), R ₁ is CH ₂ CH ₂ Z, alkyl, aryl, substituted alkyl or heterocycle, Z is halogen, sulfate group (Sulfato) group, thiosulfato group (Thiosulfato) Group, Phosphato (Phosphato) group or hydroxyl group, Y- is an anion;

In formula (II), OW is a polyacid residue in salt or acid form, and R ₂ is CH ₂ CH ₂ OW, alkyl, aryl, substituted alkyl or heterocycle. 2. The process according to claim 1, characterized in that dialkali metal-tris(β-sulfatoethyl)sulfonium internal salts are used as sulfonium compounds of the formula (II). 3. The method according to claim 2, characterized in that the inner salt of disodium-tris(β-sulfatoethyl)sulfonium is used as crosslinking agent. 4. The method as claimed in one of claims 1 to 3, characterized in that the fibers are brought into contact with the crosslinking agent in an undried state. 5. The method as claimed in one of claims 1 to 4, characterized in that the fibers are treated with alkali and then brought into contact with a crosslinking agent. 6. A method according to claim 5, characterized in that the fibers are dried before the treatment with alkali. 7. Process according to any one of claims 1 to 4, characterized in that the fibers are treated with alkali while contacting the fibers with a crosslinking agent, wherein the molar ratio of alkali to crosslinking agent is substantially 3:1 (alkali: crosslinking agent). 8. A method according to claim 7, characterized in that the fibers are dried. 9. Cellulosic fibers having a predetermined fibril tendency, obtainable according to a method according to one or more of claims 1 to 8. 10. Use of sulfonium compounds of formula (I) and/or of sulfonium compounds of formula (II) in the treatment of fibers produced by the amine oxide process and yarns and fabrics made of fibers produced by the amine oxide process, wherein R, Z and Y- have the meanings given in claim 1, wherein OW and R have the meanings given in claim ₁ . 11. Use of an internal salt of a dialkali metal-tris(β-sulfatoethyl)bone for the treatment of fibers produced by the amine oxide process and yarns and fabrics consisting of fibers produced by the amine oxide process. 12. An aqueous solution containing a base and an internal salt of a dialkali metal-tris(β-sulfatoethyl)sulfonium in the treatment of fibers produced by the amine oxide method and composed of fibers produced by the amine oxide method Applications in yarns and fabrics wherein the molar ratio of base to crosslinking agent is substantially 3:1 (base:crosslinking agent).