Polysaccharide fibers with an increased fibrillation tendency and method for the production thereof

Abstract

The present invention relates to a method for the production of polysaccharide fibers having increased fibrillation tendency, which, as a fiber-forming substance, comprise a mixture of cellulose and α(1.fwdarw.3)-glucan, as well as to the fibers made thereof and to their use.

Claims

1. A process for making a textile product that comprises a lyocell fiber, wherein the lyocell fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the lyocell fiber comprises cellulose and α(1.fwdarw.3)-glucan, and wherein the process comprises a step of mechanical or enzymatic polishing of the lyocell fiber.

2. A nonwoven product comprising a lyocell fiber, wherein said lyocell fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the lyocell fiber comprises cellulose and α(1.fwdarw.3)-glucan.

3. The non-woven product of claim 2, wherein the lyocell fiber comprises between 1% and 99% by weight of said α(1.fwdarw.3)-glucan.

4. The non-woven product of claim 2, wherein at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

5. A paper product comprising a lyocell fiber, wherein said lyocell fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the lyocell fiber comprises cellulose and α(1.fwdarw.3)-glucan.

6. The paper product of claim 5, wherein the lyocell fiber comprises between 1% and 99% by weight of said α(1.fwdarw.3)-glucan.

7. The paper product of claim 5, wherein at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

8. A textile product that comprises a lyocell fiber, wherein the lyocell fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the lyocell fiber comprises cellulose and α(1.fwdarw.3)-glucan, and wherein the textile product is selected from the group consisting of yarns, woven fabrics, and knitted fabrics.

9. The textile product of claim 8, wherein the lyocell fiber comprises between 1% and 99% by weight of said α(1.fwdarw.3)-glucan.

10. The textile product of claim 8, wherein at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

11. A nonwoven product comprising a fiber, wherein said fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the fiber comprises cellulose and α(1.fwdarw.3)-glucan.

12. The non-woven product of claim 11, wherein the fiber comprises between 1% and 99% by weight of said α(1.fwdarw.3)-glucan.

13. The non-woven product of claim 11, wherein at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

14. The nonwoven product of claim 11, wherein the α(1.fwdarw.3)-glucan has a weight-average degree of polymerization between 200 and 2000.

15. The nonwoven product of claim 14, wherein the weight-average degree of polymerization is between 500 and 1000.

16. The nonwoven product of claim 11, wherein said nonwoven product is a nonwoven fabric.

17. A paper product comprising a fiber, wherein said fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the fiber comprises cellulose and α(1.fwdarw.3)-glucan.

18. The paper product of claim 17, wherein the fiber comprises between 1 and 99% by weight of said α(1.fwdarw.3)-glucan.

19. The paper product of claim 17, wherein at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

20. The paper product of claim 17, wherein the α(1.fwdarw.3)-glucan has a weight-average degree of polymerization between 200 and 2000.

21. The paper product of claim 20, wherein the weight-average degree of polymerization is between 500 and 1000.

22. A textile product that comprises a fiber, wherein the fiber has increased fibrillation tendency and a wet abrasion resistance value (NSF value) of less than 45, wherein the fiber comprises cellulose and α(1.fwdarw.3)-glucan, and wherein the textile product is selected from the group consisting of yarns, woven fabrics, and knitted fabrics.

23. The textile product of claim 22, wherein the fiber comprises between 1 and 99% by weight of said α(1.fwdarw.3)-glucan.

24. The textile product of claim 22, wherein at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

(1) FIGS. 1 and 2 are magnified photographs of reference fibrils of pure cellulose made in accordance with Example 8.

(2) FIGS. 3 and 4 are magnified photographs of exemplary glucan-containing fibrils of the present invention made in accordance with Example 9.

DESCRIPTION OF THE INVENTION

(3) The above described object is solved by a method for the production of a lyocell fiber having increased fibrillation tendency, especially having a wet abrasion resistance value (NSF value) of less than 45, wherein the spinning solution contains aqueous amine oxide and, as a fiber-forming substance, a mixture of cellulose and α(1.fwdarw.3)-glucan. For the purposes of the present invention, such a fiber shall also be referred to as a lyocell fiber even though it contains yet another fiber-forming polysaccharide in addition to cellulose, namely, the α(1.fwdarw.3)-glucan.

(4) For the purposes of the present invention, the term “fiber” shall comprise both staple fibers having a defined staple length and continuous filaments. All principles of the invention that are described hereinafter apply, in principle, to both staple fibers and continuous filaments.

(5) The single fiber titer of the inventive fibers can be between 0.1 and 10 dtex. Preferably, it is between 0.5 and 6.5 dtex, and more preferably between 0.9 and 3.0 dtex. In the case of staple fibers, the staple length is usually between 0.5 and 120 mm, preferably between 20 and 70 mm, and more preferably between 35 and 60 mm. In the case of continuous filaments, the number of individual filaments in the filament yarn is between 50 and 10,000, preferably between 50 and 3,000.

(6) The α(1.fwdarw.3)-glucan can be prepared by bringing an aqueous solution of saccharose into contact with GtfJ glucosyltransferase isolated from Streptococcus salivarius (Simpson et al. Microbiology, vol. 41, pp 1451-1460 (1995)).

(7) In a preferred embodiment of the method according to the invention, at least 90% of the α(1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

(8) The method for the preparation of the inventive fiber consists of the following steps:

(9) 1. Preparation of a spinning solution containing aqueous amine oxide and, as a fiber-forming substance, a mixture of cellulose and α(1.fwdarw.3)-glucan, according to one of the two following methods: a. The α(1.fwdarw.3)-glucan can be added in the form of a solution in aqueous amine oxide to the cellulose solution prepared according to known methods. b. The α(1.fwdarw.3)-glucan can be admixed to the pulp already before the bringing into contact with aqueous amine oxide.

(10) 2. Extruding the spinning solution through a die, via an air gap, and into a spinning bath containing aqueous amine oxide, washing the regenerated fiber for removal of amine oxide, and drying.

(11) The concentration of the fiber-forming substance in the spinning solution can be between 5 and 20% by weight, preferably between 8 and 15% by weight, and more preferably between 10 and 14% by weight.

(12) The fiber-forming substance in the method according to the invention may comprise between 1 and 99% by weight of α(1.fwdarw.3)-glucan. Preferred is a content of the α(1.fwdarw.3)-glucan between 5 and 30% by weight and in particular preferred a content of the α(1.fwdarw.3)-glucan between 10 and 20% by weight. Below 5%, the fibrillation-enhancing effect of the added α(1.fwdarw.3)-glucan is too low for typical types of use of the inventive fibers; above 30%, fibers may to an increasing extent be caused to stick together in the spinning process. However, under certain conditions and/or for certain types of use of the inventive fibers, both limits may be exceeded; the scope of the present invention expressly also includes fibers having an α(1.fwdarw.3)-glucan content between 1 and 5% by weight and between 30 and 99% by weight, respectively. For example, in the event of a low perforation density of the spinneret, i.e., a large spacing between the individual filaments in the air gap, the risk of sticking together is significantly lower.

(13) The degree of polymerization of the α(1.fwdarw.3) glucan employed in the method according to the invention, expressed as weight average DP.sub.w, can be between 200 and 2000; values between 500 and 1000 are preferred. Preferably, the amine oxide is N-methylmorpholine-N-oxide.

(14) In the process according to the invention are also the following process parameters preferred: Extrusion temperature of the spinning solution at the dies between 90 and 135° C., preferably between 120 and 130° C.; output from the spinneret between 0.01 and 0.2 g/perforation*min, depending on the target single fiber titer, preferably between 0.02 and 0.1 g/perforation*min; length of the air gap between 7 and 70 mm, preferably between 20 and 35 mm; concentration of NMMO in the aqueous spinning bath between 0 and 35% by weight, preferably between 0 and 25% by weight.

(15) A lyocell fiber that comprises cellulose and α(1.fwdarw.3)-glucan is also subject-matter of the present invention.

(16) According to the invention, the fiber-forming substance of the inventive fiber can comprise between 1 and 99% by weight of α(1.fwdarw.3)-glucan. More preferably, the content of α(1.fwdarw.3)-glucan is between 5 and 30% by weight and most preferably the content of α(1.fwdarw.3)-glucan is between 10 and 20% by weight. Below 5%, the economic benefit of the added α(1.fwdarw.3)-glucan is too low for typical types of use; above 30%, fibers may to an increasing extent be caused to stick together. However, in certain cases and for certain types of use of the inventive fibers, both limits may be exceeded; the scope of the present invention expressly also includes fibers having an α(1.fwdarw.3)-glucan content between 1 and 5% by weight and between 30 and 99% by weight, respectively.

(17) In a preferred embodiment, at least 90% of the α(1.fwdarw.3)-glucan of the inventive lyocell fiber are hexose units and at least 50% of the hexose units are linked via α(1.fwdarw.3)-glycosidic bonds.

(18) The use of the inventive fibers for the production of textile products such as yarns, woven fabrics, or knitted fabrics is also subject-matter of the present invention.

(19) Surprisingly, it was discovered that the inventive fibers are very well suited—even better than commercially available lyocell fibers without α(1.fwdarw.3)-glucan—to produce textiles with peach-skin-effect by treatment methods generally known to those skilled in the art from the processing of lyocell fibers, for example, from Schmidt M., Lenzinger Berichte 9 (1994), pp 95-97. This suitability is due to the high fibrillation tendency of the fibres according to the invention.

(20) In order to remove fibrils, which appear in various treatment steps of the textile chain, from the fiber surface, often a so-called mechanical polishing step or also an enzymatic polishing step (“bio-polishing”; see for example Schmidt M., Lenzinger Berichte 9 (1994), pp 95-97) is employed. The inventive fibers are generally very well suited for use in a production method for textiles wherein such a step of mechanical or enzymatic polishing is employed. Hence, such use of the inventive fibers is also subject-matter of the present invention. Dyed fabrics (textiles) made out of the fibers according to the invention further show an improved white-abrasion behavior and after washing show less greying and less pilling.

(21) The inventive fibers are particularly well suited for all products that can be produced in the dry or wet laying processes. This includes for example all paper applications and nonwoven fabrics, the so-called nonwoven products. Fibrillation can also be induced by strong mechanical impact on the fibers according to the invention when they are dispersed in a liquid like e.g. water. Suitable machines are e.g. refiners, which are well-known in paper industry. Compared to Lyocell fibers consisting of 100% cellulose the fibers according to the invention are forming fibrils of larger diameter which results in a particular good suitability of such fibrillated fibers for the nonwovens applications described above.

(22) Furthermore, the inventive fibers are very well suited for all types of use where they are used in a greatly shortened form for the surface treatment of other shaped bodies or sheet-like structures. This includes surface coatings and flockings, among others. For this purpose, the inventive fibers are produced in lengths from 10 to approx. 500 μm, for example, by cutting or grinding in a cutting mill.

(23) The invention will be described below with reference to examples. However, the invention is not expressly limited to these examples but also includes all other embodiments that are based on the same inventive concept.

EXAMPLES

(24) Determination of the Fibrillation Behavior According to the Wet Abrasion Method:

(25) The method described in the publication Helfried Stöver: “Zur Fasernassscheuerung von Viskosefasern”, Faserforschung and Textiltechnik 19 (1968), issue 10, pp 447-452, was used. In the present case, the tests were conducted using an abrasion machine suited for these methods and marketed by Lenzing Instruments under the name Delta 100. Other companies make similar devices that can also be used to conduct the above mentioned method. Departing from the above mentioned publication, the fiber was moved in the longitudinal direction during the measurement in order to avoid the formation of grooves on the filament hose. The filament hose was obtained from the following source: Vom Baur GmbH & KG. Marktstraβe 34, D-42369 Wuppertal.

(26) The principle is based on the abrasion of individual fibers in the wet state by means of a rotating steel shaft covered by a viscose filament hose. The hose is constantly moistened with water. The number of revolutions until the fiber has been worn through and will break and the biasing weight triggers a contact is determined and related to the respective fiber titer. The result corresponds to the wet abrasion resistance value (NSF value). Above a wet abrasion resistance value of 300, we are talking about low fibrillation, while below a wet abrasion resistance value of 50, we are talking about high fibrillation.

(27) Test conditions: water flow volume: 8.2 ml/min; rotating speed: 500 r.p.m.; abrasion angle: 50°; biasing weight: 70 mg.

(28) Determination of the Fibrillation Behavior According to the Shake Test:

(29) 8 fibers with a length of 20 mm are filled into a 20 ml test bottle together with 4 ml water and are shaked for 9 h in a laboratory shaker, type RO-10 (manufacturer: company Gerhardt (Bonn/Germany)) at level 12.Thereafter the fibrillation behavior of the fibers is evalutated under a microscope in polarized light. This text is described e.g. in WO 1997/07266 A1.

(30) The degree of polymerization of the α(1.fwdarw.3)-glucans was determined by means of GPC in DMAc/LiCl. Subsequently, it is always the weight average of the degree of polymerization (DP.sub.w) that is specified.

Examples 1-7

(31) Spinning solutions each containing 13% by weight of solids (cellulose+α(1.fwdarw.3) glucan)/77% by weight of N-methylmorpholine-N-oxide/10% by weight of water were spun at 130° C. from a spinneret via an air gap (length 30 mm) in water. In the air gap, dry air (i.e., humidity=0% r.h.) resp. with humid air (i.e. a humidity of 80% r.h.) was used for blowing at room temperature. The output from the spinneret was 0.05 g/perforation*min. The cellulosic raw material used was Saiccor pulp having a SCAN viscosity of 450 ml/g. α(1.fwdarw.3) glucans having two different degrees of polymerization were used. The glucan quantities are related to the proportion of the α(1.fwdarw.3)-glucan in the fiber-forming substance.

(32) The properties of the fibers obtained are listed in Table 1:

(33) TABLE-US-00001 TABLE 1 quantity of glucan titer FFk FDk FFn FDn NSF example additive % % r.h. dtex cN/tex % cN/tex % U/dtex 1 none — 0 1.58 34.2 10.1 27.0 11.9 50 reference example 2 glucan 5 0 1.58 34.5 11.2 26.4 14.7 43 DP.sub.w1000 3 glucan 10 0 1.59 31.8 10.7 20.9 14.7 26 DP.sub.w1000 4 glucan 20 0 1.61 27.4 9.2 16.3 9.2 5 DP.sub.w1000 5 glucan 20 0 1.65 25.4 9.6 18.6 10.7 7 DP.sub.w 800 6 none — 20 1.33 33.2 11.4 28.7 15.5 52 reference example 6 glucan 20 20 1.23 26.9 9.6 18.4 10.7 11 DP.sub.w 1000 Therein means: FFk fiber strength, conditioned FDk fiber elongation, conditioned FFn fiber strength, wet FDn fiber elongation, wet NSF fibrillation behavior (revolutions per dtex until fiber break)

Examples 8-9

(34) Spinning solutions each containing 13% by weight of solids (cellulose+α(1.fwdarw.3) glucan)/76% by weight of N-methylmorpholine-N-oxide/11% by weight of water were spun at 120° C. from a spinneret via an air gap (length 25 mm) in 25% aqueous NMMO solution. In the air gap, humid air (i.e. a humidity of 80% r.h.) was used for blowing at room temperature. The output from the spinneret was 0.05 g/perforation*min. The cellulosic raw material used was Saiccor pulp having a SCAN viscosity of 450 ml/g. The glucan quantities are related to the proportion of the α(1.fwdarw.3)-glucan in the fiber-forming substance. The properties of the fibers obtained are listed in Table 2:

(35) TABLE-US-00002 TABLE 2 quantity of glucan titer FFk FDk FFn FDn NSF example additive % % r.h. dtex cN/tex % cN/tex % U/dtex 8 none — 80 1.26 35.7 10.1 29.7 15.0 53 reference example 9 glucan 20 80 1.23 31.8 10.3 23.8 14.0 23 DP.sub.w1000

(36) Optical Evaluation of the Fibrillation According to the Shake Test:

(37) After 9 h shaking time the glucan-containing fibers according to the invention of example 9 (FIGS. 3 and 4) show—compared to the pure cellulose fibers of example 8 (FIGS. 1 and 2) a completely different appearance of the fibrils. This shows that the fibers according to the invention form significantly longer and thicker fibrils.