Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
  • D01F2/06—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from viscose
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
  • D01F2/06—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from viscose
  • D01F2/08—Composition of the spinning solution or the bath

Definitions

• the invention relates to a process for producing cellulosic shaped bodies by the viscose process.
• the invention relates to the production of fibers and filaments.
• the production of viscose fibers by the viscose process comprises the following steps
• alkali cellulose Reacting the alkalized cellulose starting material
• the pulp used in the viscose process must meet certain criteria to allow appropriate fiber qualities.
• the pulp used in the viscose process has an alpha-cellulose content of greater than 90% and has only low levels of secondary compounds, such as xylan and others
• Hemicelluloses such as mannan
• These compounds are for the most part degraded and leached out during the alkalization of the pulp at the beginning of the viscose process (FIG. 1).
• Hemicelluloses remaining in the pulp are depolymerized in pre-maturity together with the cellulose and therefore have a much lower content average molecular weight than in the starting pulp. This applies both to the use of chemical pulps and to the use of paper pulps.
• WO 95/00698 describes a process in which, during the production of Kraft pulp, initially a substantial amount of hemicellulose is removed from the production flow and is deposited again on the pulp in a later stage.
• US Pat. No. 7,390,566 B2 and WO 2007/128026 disclose the use of pulp with a relatively high proportion of xylan for producing viscose fibers.
• the use of hemicellulose-rich pulp for the production of lyocell fibers is known from WO 99/47733 A1 and WO 01/88236 A2.
• WO 2005/118950 describes the separation of beta-cellulose from lye obtained by pressing after a cold or hot alkaline extraction (CCE, HCE) of a pulp.
• the object of the present invention is in one aspect by a method for producing a cellulosic molded body by the viscose method
• a spinning mass containing cellulose xanthate dissolved which is characterized in that the cellulose xanthate xylan in a proportion of at least 1 wt.%, Based on cellulose, preferably 1 wt.% To 20 wt.%, Particularly preferably 3 wt.% To 15 wt .% is added.
• the invention relates to a obtained by the viscose cellulosic molding with a proportion of high molecular weight xylan with an average degree of polymerization (DP) of from 75 to 350, preferably from 110 to 220, of at least 0.5% by weight, based on cellulose, preferably from 2% by weight to 8% by weight.
• DP average degree of polymerization
• FIG. 1 shows the degradation of low-molecular constituents in the viscose process.
• FIG. 2 shows the molecular mass distributions of high-molecular hemicelluloses
• Figure 3 shows fiber strengths of viscose fibers having an increased content
• FIG. 4 shows the evolution of the water retention capacity (WRV) of viscose fibers by the addition of high molecular weight xylan in the solution liquor
• FIG. 5 shows the molecular weight distribution of xylan precipitated after CCE treatment of a eucalyptus kraft pulp and the molecular weight distribution of a viscose fiber after addition of this high molecular weight xylan.
• FIG. 6 shows the molecular weight distribution of a viscose fiber with a proportion of 4.8% high molecular weight xylan and its molecular weight distribution after mathematical removal of the high molecular weight xylan content.
• Cellulose molding can be achieved.
• the xylan is added to the cellulose xanthate according to the invention.
• the xylan is preferably added in the form of an alkaline solution.
• the alkaline solution may have a xylan content of 1 to 60 g / l.
• the xylan can be added to the cellulose xanthate as a constituent of an alkaline solution.
• an alkaline solution is known to be used.
• the xylan to be added.
• the xylan originates from a pressing liquor produced during the pressing off of alkalized pulp at the beginning of the viscose process.
• the xylan originates from a pressing liquor produced during the pressing off of alkalized pulp at the beginning of the viscose process.
• the pulp is alkalized at the beginning of the viscose process.
• an alkaline press liquor is obtained which contains a high proportion of xylan dissolved out by alkalization from the pulp.
• this press liquor is used as the dissolving liquor to dissolve the cellulose xanthogenate, the xylan previously dissolved out of the pulp is returned to the process, thus increasing its yield.
• This xylan is relatively low molecular weight.
• One skilled in the art would expect that addition of low molecular weight xylan would adversely affect the strength properties of the resulting fiber.
• At least a portion of the added xylan is a high molecular weight xylan having an average degree of polymerization (DP) of 75 to 350, preferably 110 to 220.
• DP average degree of polymerization
• the xylan derived from the caustic liquor of the alkalization of the pulp by the viscose process is comparatively low in molecular weight during the degradation in the alkalization (see FIG. 2). It has been shown that viscose fibers by adding such low molecular weight xylans in their properties such as strength and elongation do not fall behind conventional viscose fibers.
• the high molecular weight xylan is added in a proportion of 1% to 20%, preferably 3% to 15%, based on cellulose.
• the high molecular weight xylan may preferably originate from a hemicellulose-rich material stream obtained in the course of an extraction step in the production of a pulp.
• press liquor obtained by pressing off the pulp after extraction is removed by appropriate methods, e.g. Membrane filtration as in WO 2005/118050,
• This liquor may e.g. be added again directly as L educatelauge or as part of the cellulose xanthate.
• the present invention also relates to a cellulosic molded body obtained by the viscose process with a high molecular weight xylan content having an average degree of polymerization (DP) of 75 to 350, preferably 110 to 220, of at least 0.5% based on cellulose, preferably 2% to 8 %.
• DP average degree of polymerization
• the molding according to the invention is new, since - without the fiction, according to the proposed addition of high molecular weight xylan to cellulose xanthate - in the conventional viscose process due to the degradation and leaching of xylan no
• the cellulosic shaped body according to the invention is preferably in the form of a fiber, e.g. Staple fiber or filament fiber.
• the invention also relates to the use of fiction, contemporary cellulosic
• Shaped body in absorbent products is
• the manufacturing process follows the conventional viscose process.
• the solution solution used is a pure alkali which has been enriched with xylan or an alkali which already contains xylan.
• the lye may contain low molecular weight and / or high molecular weight xylans.
• the lye can be added together with a possibly also used dissolving water.
• Figure 2 shows the molecular weight distribution of high molecular weight xylan as prepared from a CCE liquor from coniferous or hardwood pulps. It can be clearly seen that the xylan obtained after application of a CCE stage has a much higher average molecular weight than the xylan already degraded in the mash of the viscose process.
• the xylan was added to the xanthate from a conventional beech sulfite pulp and therefore was not present during the sulfidation, but only in the subsequent process step, the dissolution of the xanthate.
• the xylan is thus not xanthogenated, but dissolved in NaOH.
• the fibers were spun out in the laboratory. Fibers were thus produced with a significantly higher content of xylan (see Table 2 below).
• a pulp (beech sulfite pulp) was mixed with about 18% NaOH, pressed and subjected to a pre-ripeness at about 34 ° C for 19 hours.
• the Lettelauge contained 0% xylan.
• the resulting dope was conventionally spun into fibers having the properties shown in Table 2, Example 1.
• the present in the fibers (low molecular weight) xylan of 0.6 and 0.7% comes from the pulp used.
• Example 2 To a xanthate according to Example 1, a Lettelauge with 8.5 g / 1 high molecular weight xylan was added. The resulting dope was spun into fibers having the properties shown in Table 2, Example 2. The xylan uptake was 63% of the high molecular weight xylan present in the L Harborlauge, which corresponds to a proportion of high molecular weight xylan of 0.7% based on the fiber.
• Example 2 To a xanthate according to Example 1, a Lettelauge with 31.7 g / 1 xylan was added. The resulting dope became fibers having the properties given in Table 2, Example 5 Spun shown properties. The xylan uptake was 60.2% of the high molecular weight xylan present in the L Harborlauge, which corresponds to a high molecular weight xylan content of 6.9% based on the fiber.
• Example 2 To a xanthate according to Example 1, a Lettelauge with 66.3 g / 1 xylan was added. The resulting dope was spun into fibers. The xylan uptake was 54.4% of the high molecular weight xylan present in the L Harborlauge, which corresponds to a high molecular weight xylan content of 10.0% based on the fiber.
• the xylan-containing solubilizer was added to the cellulose xanthate along with solvent water. Obviously due to this, there was a partial precipitation of the xylan in the spinning mass, so that the quality of the spinning solution (filter value etc.) and also those of the spun fibers lagged behind those of Examples 2 to 5.
• Viscose fibers used. After the mash of the pulp, a low-molecular-weight xylan enriched press liquor was obtained by pressing. This liquor was subjected to nanofiltration. The permeate from the nanofilter, which has only a low content of low molecular weight xylan, was then used as L Harborlauge in the pilot plant.
• Viscose fibers used. As Lenderlauge the rich low molecular weight xylan retentate from the nanofiltration described in Example 7 was used. The xylan supply in the dope was 5.67% based on cellulose. Of these, 30.0% were spun into the fiber. A fiber with 2.2% xylan was obtained.
• the molecular weight distribution in fibers was determined by size exclusion chromatography (SEC).
• SEC size exclusion chromatography
• the samples were dissolved in DMAc-LiCl (dimethylacetamide / lithium chloride).
• a MALLS detector multi-angle laser light scattering
• Further details were published by Schelosky N, Röder T, Baldinger T (1999), Molecular Distribution of Cellulosic Products by Size-exclusion chromatography in DMAc / LiCl, Paper 53, 12: 728-738.
• the high molecular weight xylan was taken up to an unexpectedly high level by the fiber.
• the uptake into the viscose fiber was 63% to 79% of the xylan offered in the Léelauge. From the filter value and the particle number it becomes clear that the
• the water retention capacity WRV could also be significantly increased by the incorporation of xylan into the viscose fiber (see Table 2 and FIG. 4). That The uptake of water and the ability to adsorb water could not only be increased, but also selectively adjusted via the xylan content of the fiber. This is z. B. for use in absorbent products a whole new way to make product features.
• the abscissa (xylan content) in Figure 4 again refers to the total content of xylan in the fiber.
• FIG. 4 also shows the water retention capacity of the fiber produced according to Example 6 (high molecular weight xylan content: 10.0%). This was 106.0%.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)

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• 2012
  • 2012-12-06 AT ATA50564/2012A patent/AT514001B1/de active
• 2013
  • 2013-12-04 WO PCT/EP2013/075575 patent/WO2014086883A1/de active Application Filing
  • 2013-12-04 ES ES13801568.0T patent/ES2622567T3/es active Active
  • 2013-12-04 PL PL13801568T patent/PL2929071T3/pl unknown
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