Highly absorbent polysaccharide fiber and use thereof

Abstract

The present invention relates to a method for the production of highly absorbent polysaccharide fibers which contain a mixture of cellulose and (1.fwdarw.3)-glucan as a fiber-forming substance, as well as to the highly absorbent fibers made thereby, and to their use.

Claims

1. A method for the production of a highly absorbent polysaccharide fiber by a xanthogenate process comprising the steps of: (a) preparing an xanthogenate comprising alkali cellulose; (b) preparing a solution comprising (1.fwdarw.3)-glucan and NaOH; (c) combining the xanthogenate of step (a) with the solution of step (b) to form a spinning solution, wherein a fiber forming substance in said spinning solution is a mixture of cellulose and (1.fwdarw.3)-glucan; and (d) extruding said spinning solution to form said polysaccharide fiber.

2. The method according to claim 1, wherein the fiber-forming substance contains between 1 and 99% by weight of (1.fwdarw.3)-glucan.

3. The method according to claim 2, wherein the fiber forming substance contains between 5 and 45% by weight of (1.fwdarw.3)-glucan.

4. The method according to claim 1, wherein the method is a viscose process.

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

6. The method according to claims 1, 2, 4, or 5, wherein the fiber is selected from the group consisting of a staple fiber and a continuous filament.

7. A highly absorbent polysaccharide fiber produced according to claim 1, wherein a fiber-forming substance of the polysaccharide fiber is a mixture of cellulose and (1.fwdarw.3)-glucan.

8. A highly absorbent polysaccharide fiber comprising a fiber-forming substance, wherein the fiber forming substance is a mixture of cellulose and (1.fwdarw.3)-glucan.

9. The fiber according to claim 8, wherein the fiber-forming substance contains between 1 and 99% by weight of (1.fwdarw.3)-glucan.

10. The fiber according to claim 8, wherein at least 90% of the (1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via (1.fwdarw.3)-glucosidic bonds.

11. The fiber according to claim 8, wherein the fiber has a water retention capacity of at least 90%.

12. The fiber according to claim 7, wherein the fiber-forming substance contains between 1 and 99% by weight of (1.fwdarw.3)-glucan.

13. The fiber according to claims 12 or 9, wherein the fiber forming substance contains between 5 and 45% by weight of (1.fwdarw.3)-glucan.

14. The fiber according to claim 7, wherein at least 90% of the (1.fwdarw.3)-glucan are hexose units and at least 50% of the hexose units are linked via (1.fwdarw.3)-glycosidic bonds.

15. The fiber according to claim 7, wherein the fiber has a water retention capacity of at least 90%.

16. The fiber according to claims 15 or 11, wherein the water retention capacity is greater than 100%.

17. The fiber according to claims 7, 12, 14, 9, or 8, wherein the fiber is selected from the group consisting of a staple fiber and a continuous filament.

18. A product comprising the fiber according to claims 7 or 8, wherein the product is selected from the group consisting of nonwovens, hygiene articles, and of other, absorbent nonwoven products and papers.

19. The product according to claim 18, wherein the hygiene products are selected from the group consisting of tampons, panty liners, and diapers.

20. A textile product comprising the fiber according to claims 7 or 8, wherein the textile product is selected from the group consisting of yarns, woven fabrics, and knitted fabrics.

Description

DESCRIPTION OF THE INVENTION

(1) The above described object is solved by a method for the production of a highly absorbent polysaccharide fiber by using a xanthogenate process, wherein the fiber-forming substance contains a mixture of cellulose and (1.fwdarw.3)-glucan. According to the invention, this is accomplished in that an (1.fwdarw.3)-glucan-containing sodium hydroxide solution is added to the cellulose xanthogenate solution. The addition of this glucan solution can take place at various locations of the process. For the purposes of the present invention, such a polysaccharide fiber shall also be referred to as viscose or modal fiber even though, in addition to cellulose, it also contains another fiber-forming polysaccharide, namely, said (1.fwdarw.3)-glucan.

(2) 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 generally apply to both staple fibers and continuous filaments.

(3) 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 6.0 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.

(4) The (1.fwdarw.3)-glucan can be prepared by bringing an aqueous solution of saccharose into contact with glucosyltransferase (GtfJ) isolated from Streptococcus salivarius (Simpson et al., Microbiology, vol. 41, pp 1451-1460 (1995), U.S. Pat. No. 7,000,000).

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

(6) Generally, the method for the production of the inventive fiber consists of the following main steps:

(7) 1a. Preparing alkali cellulose, and its xanthogenation.

(8) 1b. Preparing an alkaline glucan solution.

(9) 2. Mixing of the two solutions.

(10) 3. Extruding the (1.fwdarw.3)-glucan-containing spinning solution through a spinneret into a sulfuric acid spin bath, stretching the fibers, and post-treatment.

(11) The total concentration of the fiber-forming substance in the spinning solution can be between 4 and 15% by weight, preferably it is between 5.5 and 12% by weight.

(12) In the inventive method, the fiber-forming substance can contain between 1 and 99% by weight of (1.fwdarw.3)-glucan. More preferably, the content of the (1.fwdarw.3)-glucan is between 5 and 45% by weight. Below 5%, the effect of the added (1.fwdarw.3)-glucan is too small for typical types of use of the inventive fibers; above 45%, competing reactions for the CS.sub.2 in the spinning solution become too intensive, and the spinnability of the solution decreases significantly. 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 encompasses fibers having an (1.fwdarw.3)-glucan content between 1 and 5% by weight and between 45 and 99% by weight, respectively.

(13) Preferably, the remaining part of the fiber-forming substance consists substantially of cellulose. As used in this context, substantially means that low quantities of other substances can be present which primarily originate from the cellulosic raw material, generally from said pulp. Such other substances include primarily hemicellulose and other saccharides, lignin residues, or the like. They are also contained in commercially available viscose and modal fibers.

(14) However, the scope of the present invention shall expressly also include such fibers that, in addition to the constituents mentioned so far, also contain other polysaccharides or functional additives as generally known in the nonwoven and textile industries.

(15) The degree of polymerization of the (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.

(16) A highly absorbent polysaccharide fiber produced by using a xanthogenate process and containing cellulose and (1.fwdarw.3)-glucan is also the subject-matter of the present invention. The fiber-forming substance of the inventive fiber contains between 1 and 99% by weight of (1.fwdarw.3)-glucan, preferably between 5 and 45% by weight of (1.fwdarw.3)-glucan.

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

(18) Surprisingly, it was discovered that the inventive fiber has an extraordinarily high water retention capacity of at least 90%. Depending on composition and production method, the water retention capacity is even greater than 100%.

(19) The use of the inventive fibers for the production of various dry-laid and wet-laid papers, nonwovens, hygiene articles such as tampons, panty liners, and diapers, and of other nonwovens, especially absorbent nonwoven products, but also of textile products such as yarns, woven fabrics, or knitted fabrics is also the subject-matter of the present invention.

(20) 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

(21) The degree of polymerization of the (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.

Example 1

(22) An aqueous viscose xanthogenate solution containing 29.8% by weight of cellulose, 14.9% by weight of NaOH, and 8% by weight of sulfur was reacted in a dissolving unit with a first dissolving liquor containing 4.5% by weight of NaOH and then with a second dissolving liquor containing 9% by weight of (1.fwdarw.3)-glucan and 4.5% by weight of NaOH, and finally with water. The viscose obtained in this way contained 8.90% by weight of fiber-forming material, 5.20% by weight of NaOH, and 2.4% by weight of sulfur (for 100% of cellulose as a fiber-forming material), with a ripeness index of 14 Hottenroth and a falling ball viscosity of 80 seconds (determined according to the Zellcheming Leaflet III/5/E). Viscose solutions with 10 and 25% of (1.fwdarw.3)-glucan were prepared. The glucan quantities were related to the proportion of the (1.fwdarw.3)-glucan in the fiber-forming substance. These viscose types contain 2.2% by weight of sulfur (10% of glucan and 90% of cellulose as the fiber-forming material) and 1.8% by weight of sulfur (25% of glucan and 75% of cellulose as the fiber-forming material), respectively. By using a spinneret, the solution was extruded into a regeneration bath containing 100 g/l of sulfuric acid, 330 g/l of sodium sulfate, and 15 g/l of zinc sulfate. The spinneret had 1053 perforations with a diameter of 50 m. 0.5% by weight of a nitrogen-containing auxiliary agent were added to the viscose spinning solution. In order to achieve adequate fiber strength, stretching by approx. 75% was carried out in the secondary bath (92 C., 15 g/l of H.sub.2SO.sub.4). The draw-off velocity is 50 m/min.

(23) In a reference example 1, the viscose from Example 1 was spun into fibers without the addition of the glucan/NaOH solution, but otherwise in the same conditions as in Example 1.

(24) The properties of the obtained fibers are listed in Table 1.

Example 2

(25) A viscose containing 8.70% by weight of cellulose, 5.20% by weight of NaOH, and 2.3% by weight of sulfur, with a ripeness index of 15 Hottenroth and a falling ball viscosity of 75 seconds (determined according to the Zellcheming Leaflet III/5/E) was, by means of a spinneret, extruded into a regeneration bath containing 100 g/l of sulfuric acid, 310 g/l of sodium sulfate, and 15 g/l of zinc sulfate. The spinneret had 1053 perforations with a diameter of 50 m. 0.5% by weight of a nitrogen-containing auxiliary agent were added to the viscose spinning solution. In order to achieve adequate fiber strength, stretching by approx. 75% was carried out in the secondary bath (92 C., 15 g/l of H.sub.2SO.sub.4). The draw-off velocity is 50 m/min.

(26) By using a positive displacement pump, suitable quantities of an aqueous (1.fwdarw.3)-glucan/NaOH solution (5% by weight of NaOH, 8% by weight of (1.fwdarw.3)-glucan) were added to the viscose solution upstream from the spinneret so that fibers having 10, 15, and 30% of glucan could be produced. These glucan quantities were related to the fraction of the (1.fwdarw.3)-glucan in the total fiber-forming substance of the polysaccharide fibers.

(27) In a reference example 2, the viscose from Example 2 was spun into fibers without the addition of the glucan/NaOH solution, but otherwise in the same conditions as in Example 2.

(28) The properties of the obtained fibers are listed in Table 1.

(29) TABLE-US-00001 TABLE 1 quantity of glucan titer FFk FDk WRV example additive % dtex cN/tex % % reference none 1.7 27.4 16.2 86 example 1 1a glucan 10 1.7 27.4 16.5 94 DP.sub.w800 1b glucan 20 1.7 24.7 14.6 107 DP.sub.w800 reference none 1.3 29.6 15.8 87 example 2 2a glucan 10 1.3 28.6 17.9 95 DP.sub.w1000 2b glucan 15 1.3 26.1 18.1 116 DP.sub.w1000 2c glucan 25 1.3 23.6 19.4 124 DP.sub.w1000 FFk fiber strength, conditioned FDk fiber elongation, conditioned WRV water retention capacity