Cellulose and lyocell tablets with reduced cellulose content
The present invention describes special pulp compositions which allow a lyocell fiber with a reduced cellulose content to be produced on an industrial scale in a stable manner, as well as the lyocell fiber produced therefrom.

State of the art

Lyocell fibers are used in a variety of applications. Purified cellulose is often used as a raw material, with a very low proportion of components other than cellulose.

Cellulose is obtained from wood, which consists of only 40-44% by weight of cellulose. Since a high content of cellulose in the pulp of over 95% by weight is generally required for the production of lyocell molded bodies, a large part of the raw material is lost for material use during cooking and bleaching. A large number of possibilities are known to specifically reduce the proportion of hemicelluloses, both in the production of pulp on the way from the wood to the pulp or to the lyocell end product:

a) Digestion: A large part of the hemicelluloses is lost in the sulphite boil; while in the alkaline digestion, the pre-hydrolysis, especially to remove the hemicelluloses, takes place before the boil.

b) Bleaching: usually to eliminate residual lignin and / or to brighten up the appearance, but also destroys hemicellulose components

c) Partial insolubility of branched hemicellulose components in Lyocell solvent d) Degradation in DOPE with subsequent dissolution in the spinning bath

It is true that there are strong efforts to use these other components materially as by-products. The implementation takes place only in small amounts due to known technical restrictions. In the waste liquors from cellulose production, these other wood components are present in the form of a large number of different degradation products, also mixed with strong acids or alkalis, which makes separation and further processing extremely difficult. WO 98/16682 describes a production method for a cellulose composition suitable for fiber production. A starting mixture that is not considered suitable for fiber production (but only for paper production) is processed in such a way that the hemicellulose content, in particular the xylan content, is reduced.

Nevertheless, efforts have been made in recent years to broaden the raw material base for lyocell products by using celluloses with an increased proportion of lignin and / or hemicelluloses.

US 6440523 and US 6444314 describe such approaches as examples:

The approach pursued in these documents essentially consists in describing either the corresponding cellulose (pulp) and / or the lyocell products made therefrom which, in addition to the cellulose content, also have a hemicellulose content of more than 5% by weight. However, in all of these documents it is considered essential that the higher hemicellulose proportions described there are only possible if a number of further essential conditions are met at the same time. These are, for example, a certain viscosity of the pulp, a maximum copper number and / or a maximum Kappa number.

Although lyocell products are described in these documents, it is noteworthy that the developments based on these protective rights have not yet been implemented on an industrial scale, although the use in particular of pulps with a higher hemicellulose content should bring significant cost and thus competitive advantages. This could probably be due to the difficulties in scaling up from the laboratory scale and the achievable fiber properties, which do not meet the expectations of the textile and nonwovens market. US 2015/0184338 A1 discloses Kraft Pulp with a low content of hemicelluloses.

Object of the invention

In the sense of the highest possible use of resources, it would be desirable to be able to use as many material components as possible from the raw material wood for the production of a lyocell fiber. The primary goal in striving for the greatest possible sustainability and a really effective biorefinery concept must be to use the natural raw material wood as extensively as possible for the main product, namely lyocell moldings, right from the start. The extraction of by-products remains of great importance, but overall this remains subordinate. The efforts made so far have failed,

On the contrary, for the large-scale use of chemical pulp in the Lyocell process, a large number of patents and publications demand that the content of lignin, hemicelluloses and accessory components should be extremely low.

For these reasons, it is desirable to provide technologies that can be used on an industrial scale and that reduce the cellulose content in the finished fiber

Enabling an increase in the proportion of other wood components, in particular hemicelluloses, but also lignin, without significant restrictions in relation to the resulting material parameters. In spite of the large number of approaches in the state of the art, there are currently none

Process for the production of such Lyocell products which can be used on an industrial scale

reduced cellulose content known.

Brief description of the invention

The aforementioned problems in the prior art are overcome by the present invention. The present invention provides a pulp according to claim 1, a lyocell product according to claim 9, and the methods according to claims 16 and 18. Preferred embodiments of the invention are given in the subclaims and the following detailed description of the invention.

In particular, the present invention provides the following aspects, as well as the preferred embodiments listed in the subclaims and the description.

1. Cellulose, suitable for the production of Lyocell moldings, with a proportion of cellulose of 90 wt .-% or less, preferably 85 wt .-% or less and a proportion of hemicelluloses of at least 7 wt .-%, characterized in that the The ratio of the C5 / xylan to the C6 / mannan fraction (C5 / C6 ratio) present in the hemicellulose is in the range from 125: 1 to 1: 3.

2. Pulp according to embodiment 1, wherein the C5 / C6 ratio is in the range from 25: 1 to 1: 2.

3. Pulp according to embodiment 1 and / or 2, the proportion of hemicelluloses being 10% by weight or more.

Cellulose according to at least one of the preceding embodiments, the hemicelluloses of which are in the native state, have been chemically modified by processing processes or have been chemically modified or functionalized in a separate process step.

Pulp according to at least one of the preceding embodiments, with a lignin content of more than 1% by weight.

Pulp according to at least one of the preceding embodiments, wherein the cellulose content is further reduced by the presence of lignin, accessory components from the wood and / or the addition of metallic compounds.

Pulp according to at least one of the preceding embodiments, with a xylan content of 9% by weight or more and / or a mannan content of 6% by weight or more.

Pulp according to embodiment 7, having a xylan content of 9% by weight or more and a mannan content of 1% by weight or less.

Lyocell molded body produced using the cellulose according to one of embodiments 1 to 8.

Lyocell molded body according to embodiment 9, wherein the molded body is selected from fibers, filaments, staple fibers, nonwoven fabrics, films and powders in spherical shape.

Lyocell molded body according to at least one of embodiments 9 and / or 10, wherein the molded body is a fiber, a filament or a staple fiber with a cellulose content of less than 90% by weight, a hemicellulose content of more than 5% by weight and a C5 / C6 ratio of 125: 1 to 1: 3, preferably 25: 1 to 1: 2.

Lyocell molded body according to at least one of embodiments 9 to 11, the hemicellulose content being more than 10% by weight.

Lyocell molded body according to at least one of embodiments 9 to 12, wherein the molded body is a fiber, a filament or a staple fiber with a WRV of greater than 70%, preferably greater than 75%, in particular greater than 80%.

Lyocell molded body according to at least one of embodiments 9 to 13, wherein the molded body has a crystallinity of 40% or less.

Lyocell molded body according to at least one of embodiments 9 to 14, with a lignin content of more than 0% by weight up to 5% by weight.

A method for producing a lyocell molded body, comprising the dissolution of a cellulose with a proportion of cellulose of 90% by weight or less, preferably 85% by weight or less and a proportion of hemicelluloses of at least 7% by weight, characterized in that the ratio of the C5 / xylan to the C6 / mannan fraction (C5 / C6 ratio) present in the hemicellulose is in the range from 125: 1 to 1: 3, in a suitable solvent, and the solution is formed into a lyocell molding.

Method according to embodiment 16, wherein the lyocell molded body is obtained by a lyocell spinning process.

A method for producing a pulp according to any one of embodiments 1 to 8, the method comprising at least one of the following steps:

a) mixing a pure pulp with xylan and / or mannan;

b) treating a pulp with a hemicellulose portion including mannan, by chemical and / or physical processes in order to modify the hemicellulose portion and / or the composition of the hemicellulose contained;

c) production of a pulp using conifer and / or hardwood;

d) mixing a mannan-free pulp with a hemicellulose-rich pulp and optionally subsequent chemical and / or physical treatment of the mixture to adjust the hemicellulose content and / or the composition of the hemicellulose portion;

e) Mixing two pulps with different hemicellulose content and / or hemicellulose composition, and optionally subsequent chemical and / or physical treatment of the mixture to adjust the hemicellulose content and / or the composition of the hemicellulose portion.

Method according to embodiment 18, wherein the different pulps are selected from hardwood and softwood-based pulps.

Brief description of the figures

Figure 1 shows the correlation of crystallinity and water retention capacity of lyocell fibers of the present invention and of standard lyocell fibers.

Fig. 2 shows the ratio of xylan to mannan in sulphite pulp as a function of the H-factor when using beech wood.

Fig. 3 shows the ratio of xylan to mannan in sulfite pulp as a function of the H-factor when using spruce wood.

Detailed description of the invention

If the proportion of cellulose is reduced in the Lyocell process, this means that the savings should be made up for by other substances from the wood raw material. The problem of process stability or the change in properties arises when the cellulose content is reduced, as already stated above. The essential proportions of non-cellulosic material in the raw material wood are the hemicelluloses (mainly polyoses from the sugar monomers xylose, arabinose, mannose, galactose, glucose and rhamnose), lignin and accessory components.

Cellulose: It represents the structural substance of the cell walls in wood and is mainly used for tensile strength. The long molecular chains made up of glucose units are arranged in so-called fibrils several times in a helical structure. This helical arrangement in the cell wall ensures good flexural strength of the tree, for example in the event of wind load or the wood e.g. B. in a roof structure. Cellulose is hydrophilic but, due to its high crystallinity, is not soluble in water.

Lignin: Binder for the firm bond of the cellulose in the form of an amorphous matrix. Lignin is mainly responsible for the compressive strength, but on the other hand it is not very flexible and, in contrast to cellulose, it is hydrophobic. It is responsible for the stamina of the tree. Plants that do not store lignin only reach low heights. Lignin is relatively stable biologically and only slowly biodegrades.

For the purposes of the present invention, hemicellulose are components present in wood in the form of short-chain polymers composed of C5 and / or C6 sugars. In contrast to cellulose, they have side groups and can therefore only form crystals to a much lesser extent. Its basic building blocks are mannose, xylose, glucose, rhamnose and galactose. The side groups preferably consist of arabinose groups, acetyl groups and galactose residues as well as O-acetyl groups and 4-O-methylglucuronic acid side groups. It is known that mannans tend to be associated with cellulose, while xylans tend to associate with lignin. The composition of the hemicelluloses is very different depending on the type of wood used. In the course of the manufacturing process in the manufacture of cellulose, side chains are partially separated and the polymer chains are split up. In the context of this invention, the term hemicelluloses includes those in their native structure as well as those that have been changed through their processing and also those that have been adjusted for the respective intended use through targeted chemical modification. Short-chain celluloses and other polyoses with a DP of up to 500 are also included.

Accessory components: Accessory components are organic and inorganic accompanying substances from the wood that are not lignin, cellulose and hemicellulose, and usually salts and low molecular weight organic compounds with up to about 100 atoms, such as tannins, resins, fats and waxes , Tannins and humic substances, terpenes, terpenoids and phenolic compounds, pectins, suberins, polyphenols and polyoses.

If the cellulose content is now reduced as desired in a cellulose material and other components of the raw material wood are to compensate for this reduction, it has surprisingly been shown that it is only possible by combining different types of sugar in a certain ratio, a pulp indicate which, despite its reduced cellulose content, reliably enables large-scale production of lyocell products, these products also having a reduced cellulose content, but nevertheless having satisfactory product properties.

According to the invention it is essential that with a reduced cellulose content in the pulp of less than 90 wt .-%, a proportion of hemicelluloses of at least 7 wt .-% is present, wherein the ratio of sugars with five carbon atoms such. B. xylan to sugars with six carbon atoms such. B. mannan (hereinafter referred to as the C5 / C6 ratio) is in the range from 125: 1 to 1: 3.

With such a pulp, the large-scale production of lyocell products can surprisingly be realized safely, although the cellulose content in the pulp is reduced.

The pulps used here, which are preferably used in the context of the present invention, show, as already stated, a relatively high content of hemicelluloses with the composition defined here. In comparison with standard pulps with a low hemicellulosic content, used in particular in the prior art for the production of standard lyocell fibers, the pulps preferably used in the context of the present invention also show further differences, which are listed below.

In comparison with standard pulps, the pulps preferably used in the context of the present invention show a rather fluffy appearance. After grinding (during the production of starting materials for the production of spinning solutions for the Lyocell process), this results in a particle size distribution with a high proportion of larger particles. As a result, the bulk density is much lower compared to standard pulps with a low hemicellulosic content. Such a low bulk density requires adaptations with regard to the dosage parameters (eg dosage using at least two storage containers) in the production of the spinning solutions. In addition, the pulps preferably used in the context of the present invention show an impregnation behavior towards NMMO, in comparison with standard cellular fabrics, this shows that impregnation is more difficult here. This can be checked by evaluating the impregnation behavior with the Cobb evaluation. While standard pulps typically show a Cobb value of more than 2.8 g / g (determined in accordance with DIN EN ISO 535 with adaptations with regard to the use of an aqueous solution of 78% NMMO at 75 ° C with an impregnation time of two minutes) the pulps preferably used in the context of the present invention show Cobb values ​​of about 2.3 g / g. This requires adaptations during the production of spinning solutions, such as increased dissolution time (e.g. explained in WO 94/28214 and WO 96/33934) and / or temperature adjustment and / or increased shear during dissolution (e.g. WO 96/33221 , WO 98/05702 and WO 94/8217).

In a preferred embodiment of the present invention, the pulp used for the production of lyocell products, preferably fibers, as described here, has a SCAN viscosity in the range from 300 to 440 ml / g, in particular 320 to 420 ml / g, more preferably 320 to 400 ml / g. The SCAN viscosity is determined in accordance with SCAN-CM 15:99, using a cupriethylenediamine solution, a method known to those skilled in the art and which can be performed with commercially available devices such as the Auto PulpIVA PSLRheotek device available from from PSL-Reotek. The SCAN viscosity is a

important parameter that particularly influences the processing of pulp in the production of spinning solutions. Even if two pulps show a great similarity with regard to their composition etc., different SCAN viscosities lead to completely different behavior during processing. In a direct solution spinning process, such as the Lyocell process, the pulp is dissolved in NMMO as such. There is no ripening step, comparable to the viscose process, for example, where the degree of polymerisation of the cellulose can be adapted to the requirements of the process. Therefore, the specifications for the viscosity of a raw pulp are typically within a small target window for the lyocell process. Otherwise problems can arise during production. In accordance with the present invention, it has been found that the pulp viscosity is preferably as described above. Lower viscosities lead to a deterioration in the mechanical properties of the Lyocell products. Higher viscosities can in particular lead to an increased viscosity of the spinning solution, so that spinning becomes slower overall. With lower spinning speeds, lower draw ratios are also obtained, which can again have a significant influence on the fiber structure and the fiber properties (Cabohydrate Polymers 2018, 181, 893-901). This would require process adaptations that would lead to a reduction in capacity.

The expression "Lyocell process" or the expressions "Lyocell technology" and "Lyocell process", as they are used here, designate a direct dissolution process of wood cellulose pulp or other cellulose-based starting materials in a polar solvent (e.g. N-methylmorpholine -n-oxide (NMMO, NMO) or ionic liquids). Commercially this tech nology is used to produce a group of cellulose staple fibers, commercially available from Lenzing AG, Lenzing, Austria under the brand name TENCEL ®or TENCEL ™), which are widely used in the textile and nonwoven industries. Other molded cellulose bodies obtained through lyocell technology have also already been produced. In accordance with this method, the cellulose solution is usually extruded in a so-called dry-wet-spinning process, using a molding tool and the shaped solution reaches, for example, after passing an air gap in a precipitation bath, where the shaped body is obtained by the precipitation of the cellulose. The shaped body is washed and optionally dried, after further treatment steps. A method for the production of lyocell fibers is described, for example, in US 4246221, WO 93/19230, WO 95/02082 or WO 97/38153. As far as the present invention discusses the disadvantages of the prior art,

In connection with (semi-commercial) pilot plants and commercial fiber spinning units, the present invention is to be understood in such a way that it refers to units which, with regard to their respective production capacities, can be defined as follows:

Semi-commercial pilot plant: around 1 kt / a

Commercial unit greater than 30 kt / a

In the context of the present invention it has been shown that, in particular during fiber production in the context of a Lyocell process, an orientation in the direction of production and a stretching of the fibers take place. From an initially more or less disoriented mix of different polymers and other ingredients in the dope

a first orientation of the polymers in the direction of production is achieved through the strong cross-sectional constriction at the spinneret. The additional stretching in the air gap after the spinneret and during the following process steps results in a stretched, oriented fiber structure of the polymers. These processes are well known from the specialist literature.

The fiber properties are strongly influenced by the type and the way in which the polymers are stored together. It is also known that cellulosic fibers which are produced according to the Lyocell process have a very high crystallinity of approx. 44 to 47%, while fibers from the viscose process have a crystallinity of approx. 29 to 34%. The crystallinity describes the alignment of the cellulose polymers to one another and thus, for example, their ability to absorb, swell and store water. In addition, the polymer chains in the non-crystalline areas of Lyocell fibers are more ordered than in viscose fibers. As a result, ordinary Lyocell fibers swell less and are less suitable for highly absorbent products than viscose fibers.

By using the pulps according to the invention with a reduced cellulose content, a completely different type of aggregation of the polymers and thus a different structure of the Lyocell fibers is unexpectedly made possible. Their crystallinity is significantly lower, typically 40% or less, such as 39% or less and, for example, in the range from 38% to 30%, such as, for example, in the range from 37 to 33%.

The values ​​for WRV for fibers in accordance with the present invention, isolated or in combination with the other preferred embodiments described here, preferably in combination with the values ​​described here for the crystallinity of the fiber, are preferably 70% or more, in particular 75 % or more, such as 80% or more, for example from 70 to 85%.

It is known from the literature that xylans also form a crystal structure if their side chains were split off in the course of the production process and they are precipitated from a pure xylan solution (Fengel, Wegener p. 113; Fengel D, Wegener G (1989) : Wood, Chemistry, Ultrastructure, Reactions; Walter de Gruyter Verlag). The same applies to Mannan (ibid; p.119). In the present invention, however, opposite effects are exhibited. The polymers including the cellulose are present in a mixture in the dope and are thus also spun out and precipitated. The hemicelluloses also have side groups, since the glucuronic acid side groups of the xylan are comparatively stable under the conditions of acid digestion (Sixta H (Ed.) (2006): Handbook of Pulp Vol. 1; Wiley VCH p. 418). The hemicelluloses therefore meet all the requirements to disrupt the crystal formation of the cellulose and thus to form a more disordered structure compared to standard Lyocell fibers. The person skilled in the art would therefore expect that unusable products, in particular fibers, would result with a higher hemicellulose content and a reduced cellulose content. However, it has unexpectedly been shown that the hemicelluloses content in combination with the C5 / C6 ratio can be used to control product properties in a targeted manner. This mixture of different sugar polymers still achieves crystallinity values ​​that are higher than the crystallinity values ​​of viscose fibers, but now the overall accessibility of the fiber to water is increased, so that the water retention capacity (WRV) can be significantly increased. This improved absorbency is of decisive advantage for various areas of application, e.g. B. for use in the nonwovens sector. This relationship between decreasing crystallinity and increasing water retention capacity for Lyocell fibers is shown in Figure 1 and, as described above, can be adjusted by the targeted reduction of the cellulose content in the fiber.

[0029] As shown in the examples, the qualities of the new Lyocell fibers with a reduced proportion of cellulose which are conventional TENCEL ® fibers similar. It becomes clear that the fiber strengths are slightly below those of the TENCEL ® fibers, measured in the examples as strength and work capacity . At the same time, the cellulose content could be reduced significantly, recorded in the examples as a glucan value. The absorption of other wood components reduces the crystallinity by up to 21% and the absorbency increases significantly by up to 27%, measured in the examples as the crystallinity index and water retention capacity. Interestingly, lie the crystallinity of the new lyocell invention between those of conventional TENCEL ®Fibers and nonwovens Lenzing Viscose ® fibers, at the same time the WRV is in the range of Lenzing Viscose ® . The WRV increases more than it could be explained by the decreasing crystallinity of the fibers. This is a clear indication of the unexpected properties that can be realized with the present invention. The other components such as in particular

Hemicelluloses, but also lignin and accessory components from wood not only ensure a significant increase in yield, i.e. improved sustainability, but also a significant improvement in product properties, such as water retention.

Embodiments

As defined in claim 1, the pulp according to the invention is characterized by a reduced cellulose content, a minimum content of hemicelluloses and a certain C5 / C6 ratio with regard to the composition of the hemicellulose.

In a preferred embodiment, the pulp, which can also be a mixture of different pulps (as long as the essential conditions are met), is a pulp which has a hemicellulose content of 7 to 50% by weight, preferably 7 to 30% by weight. %, more preferably 15 to 25% by weight, such as 10 to 20% by weight.

The pulp to be used according to the invention is furthermore preferably a pulp which has a xylan content of at least 9% by weight, preferably a content of at least 10% by weight. The proportion of mannan can, in combination or independently thereof, be selected within a wide range, as long as the ratio defined according to the invention is met. Suitable mannan contents are in the range from 0.1 to 10% by weight, such as from 0.1 to 9% by weight and in embodiments from 0.1 to 6% by weight, from 0.1 to 4% by weight %, from 5 to 10% by weight, from 6 to 10% by weight etc. In embodiments, the mannan content is in the range from 0.1 to 1% by weight, preferably in combination with a xylan content of at least 9% by weight. -%, preferably at least 10% by weight. In other embodiments the mannan content is higher, preferably in the range of 6% by weight or more.

In a preferred embodiment, isolated or in combination with the embodiments described above and below, the cellulose content in the pulp is in a range of equal to or less than 90% by weight to 50% by weight, preferably in the range of 90 Wt% to 60 wt%, such as from 85 wt% to 70 wt%.

The weight ratio of cellulose to hemicellulose can be in the range from 1: 1 to 20: 1. The proportion of accessory components can be more than 0.05% by weight, preferably more than 0.2% by weight, more preferably more than 0.5% by weight. It has unexpectedly been shown that with such proportions of accessory components in the pulp according to the invention, the effect can be supported that the C5 / C6 ratio is stable in the lyocell products produced, especially fibers, and the hemicellulose content does not change significantly (i.e. the Content does not decrease in the lyocell product or only to a small extent compared to pulp).

In a further preferred embodiment, such a high retention capacity is achieved by the inventive C5 / C6 ratio that at the same time a proportion of metal compounds, usually present as their oxides and hydroxides of up to 25 wt .-% based on the Weight of the Lyocell product (e.g. Mg (OH) 2 0derAI (OH) 3ZU flame retardant purposes) is made possible, which further reduces the cellulose content substantially. Such metal compounds are in particular PO2, Al2O 3, MgO, S1O2, Ce02, Mg (OH) 2, Al (OH) 3, BN, ZnO and partly come from the mineral components of the wood or can be used as functional additives in the cellulose solution (flame retardant, Matting agents, biocides ...) can be added.

In a further preferred embodiment, lyocell fibers can be produced with a cellulose content reduced to below 70%, which not only meet the practical requirements in comparison with the known lyocell fibers (mechanical strengths, etc.), but also due to the new properties resulting from the invention are even better suited for some applications. The corresponding investigations have shown that fibers in the proposed composition have, in particular, an increased water retention capacity and rapid biodegradability during composting.

According to the invention, the ratio of C5 / C6 sugars of the non-cellulosic polymers has been shown to be an important factor for setting the fiber composition and its properties resulting therefrom. Targeted setting of this ratio, also in combination with the hemicelluloses content, enables the desired product properties to be set in a targeted manner.

In this context, the person skilled in the art knows how to control or set the C5 / C6 ratio. This can be achieved by a mixture of different pulps such as B. Softwood pulps with a higher proportion of mannan can be achieved with hardwood pulps with a higher proportion of xylan. Tests have confirmed another very effective way of making the appropriate setting. Through a targeted setting of the cooking parameters such. B. the H-factor, the ratio of C5 to C6 sugars can be controlled. This is illustrated in Figures 2 and 3. The H-factor is an essential parameter for controlling sulphite boiling (Sixta (Vol. 1 2006) p. 432). It combines cooking temperature and cooking time as one variable.

Figure 2 shows the influence of the H-factor in the sulfite boiling on

Hemicellulose ratio in hardwood using the example of beech. In hardwoods, the xylan content is naturally higher. With increasing H-factor, xylan is broken down more strongly than mannan. The ratio C5 / C6 decreases.

When using softwood, the hemicellulose ratio is the other way around. The proportion of mannan in wood and pulp is higher. Contrary to expectations, mannan is broken down more quickly than xylan, as can be seen from FIG.

Another way to adjust the pulp composition according to the invention is the admixture of C5 and / or C6 sugars that have previously been obtained in other processes or process steps, such as. B. in an alkaline extraction, be it a cold alkali extraction or an E-stage or the like. For the production of viscose, the addition of hemicelluloses in dissolved form to the spinning mass and the subsequent joint spinning are known (WO2014086883). This enables viscose fibers to be produced with a reduced cellulose content. This is only possible because the viscose process takes place in an aqueous medium and the hemicelluloses are correspondingly alkali-soluble, so the cellulose xanthate and the dissolved hemicelluloses can be mixed together and spun out together. In contrast, the pulp is dissolved in the Lyocell process in NMMO or similar solvents, so no alkaline or aqueous solutions can be added here. They would dilute the solvent and reduce the solubility or even lead to unwanted precipitations. The hemicelluloses cannot therefore be added in the form of solutions during the production of the spinning solution, but have to be introduced into the process in a different way. One possibility is the addition in the pulp production process so that the mixture can then be dried with the pulp. They would dilute the solvent and reduce the solubility or even lead to unwanted precipitations. The hemicelluloses cannot therefore be added in the form of solutions during the production of the spinning solution, but have to be introduced into the process in a different way. One possibility is the addition in the pulp production process so that the mixture can then be dried with the pulp. They would dilute the solvent and reduce the solubility or even lead to unwanted precipitations. The hemicelluloses cannot therefore be added in the form of solutions during the production of the spinning solution, but have to be introduced into the process in a different way. One possibility is the addition in the pulp production process so that the mixture can then be dried with the pulp.

It has surprisingly been found that the precise observation of the hemicellulose composition is a crucial point for the industrial production of lyocell molded bodies, in particular fibers. The use of hemicellulose in the fiber structure that can be implemented on an industrial scale is only possible if the proportion of the C5 fraction is correlated with the proportion of the C6 fraction. The ratio of xylan to mannan is preferably between 18: 1 to 1: 3, preferably 9: 1 to 1: 2. At the same time, such a mixing ratio enables the incorporation of 0.5-5% by weight of lignin (and / or other accessories Components) into the fiber structure without adversely affecting the desired properties.

The fibers provided according to the invention have conventional fiber titers, such as 7 dtex or less, for example 2.2 dtex or less, such as 1.3 dtex, or less, possibly even lower, such as 0.9 dtex or less, in Depending on the desired application. For applications in

In the nonwoven range, titers of 1.5 to 1.8 dtex are typical, while lower titers, such as 1.2 to 1.5 dtex, are suitable for textile applications. However, the present invention also includes fibers with even lower titers, as well as fibers with significantly higher titers, such as 10 dtex or less, such as 9 dtex or less, or also 7 dtex or less. Suitable lower limits for fiber titers are values ​​of 0.5 dtex or more, such as 0.8 dtex or more and, in embodiments, 1.3 dtex or more. The upper and lower limit values ​​disclosed here can be combined and the ranges formed thereby, such as from 0.5 to 9 dtex, are also included. Surprisingly, the present invention enables the production of fibers with titers that allow use in the entire spectrum of fiber applications,

Insofar as reference is made to parameters in this application, these are determined as described here. It is essential that these parameters are obtained with the fibers as such, comprising a maximum of 1% by weight of additives, such as matting agents etc. / or affects the manufacturing process of the fibers.

The following examples illustrate aspects of the present invention.

Methods

Determination of the crystallinity index [%]

The crystallinity index is determined by means of Raman spectroscopy. This method is calibrated with data from the wide-angle X-ray method (WAX) and was developed by Röder et al. (2009) (Röder T, Moosbauer J, Kliba G, Schiader S, Zuckerstätter G, and Sixta H (2009): Comparative Characterization of Man-Made Regenerated Cellulose Fibers. Lenzinger Reports Vol. 87, p. 98 ff.).

Determination of the water retention capacity [%]

The sample is left to swell at 20 ± 0.1 ° C. overnight. After further dilution, the sample is spun off in a centrifuge according to Zellcheming-Merkblatt IV / 33/57 at 3000 times the acceleration due to gravity. The water retention capacity is then calculated as follows:

^ (Weight of wet sample - weight of dry sample),

WRV = - - - x 100

Weight dry sample

Examples

Example for setting the xylan-mannan ratio

Table 1 shows the results of setting the C5 / C6 ratio for two types of wood, using the example of the variation of the H factor in the magnesium bisulfite digestion.

Table 1: Adjustment of the xylan / mannan ratio in the magnesium bisulfite cooking of Fagus sylvatica (beech) and Picea abies (spruce) with the help of the H factor.

Example of a eucalyptus kraft pulp

In the pilot plant, a new inventive Kraft chemical pulp was produced from eucalyptus wood using the VisCBC process. The H-factor was 1200, the effective alkali in the cooking liquor was 25 g / l. The bleaching was carried out according to a TCF sequence. Relevant process information and product properties are given in Table 2.

Lyocell fiber.

In this new chemical pulp with reduced cellulose content, the xylan-to-mannan ratio was increased extremely, namely to 121 in the finished fiber, and at the same time the cellulose content was kept very low at approx. 85%. This new pulp meets the requirements of the Lyocell process for the production of the new Lyocell fiber with a reduced cellulose content in every respect.

Example of the fiber properties when using the new cellulose-reduced pulps

Table 3 summarizes the sugar monomer salaries of the starting pulps for lyocell fiber production.

Table 3: Sugar contents of cellulose-reduced pulp compared to a standard Lyocell pulp

Table 4 shows mechanical characteristic values ​​for standard fibers (lyocell and viscose) in comparison with characteristic values ​​that were achieved with lyocell fibers produced with pulps according to the invention. The results clearly demonstrate the advantages of the present invention.

Both in pilot plant tests and in the case of large-scale lyocell fibers produced in accordance with the present invention, it has been shown that values ​​for strength and working capacity that are acceptable for commercially relevant titers can be achieved, despite the significantly reduced cellulose content. At the same time, the WRV increases drastically, so that such fibers are interesting for new areas of application that were previously occupied by viscose fibers. In comparison with commercially available viscose fibers, however, significantly higher mechanical characteristics can be achieved with the lyocell fibers according to the invention.

The new lyocell fibers according to the invention thus combine the respectively advantageous properties of previously commercially available lyocell or viscose fibers.

' Abeile 4: properties of conventional cellulose and reduced lyocell fibers as compared to a standard viscose fiber.

Expectations

1. Cellulose, suitable for the production of lyocell moldings, with a proportion of cellulose of 90% by weight or less and a proportion of hemicelluloses of at least 7% by weight, characterized in that the ratio of the C5 / xylan present in the hemicellulose - to the C6 / mannan fraction (C5 / C6 ratio) is in the range from 125: 1 to 1: 3.

2. Pulp according to embodiment 1, wherein the C5 / C6 ratio is in the range from 25: 1 to 1: 2.

3. Pulp according to embodiment 1 and / or 2, the proportion of hemicelluloses being 10% by weight or more.

4. Pulp according to at least one of the above embodiments, the hemicelluloses of which are in the native state, have been chemically modified by processing processes or have been chemically modified or functionalized in a separate process step.

5. Pulp according to at least one of the preceding embodiments, with a

Lignin content of more than 1% by weight.

6. Pulp according to at least one of the preceding embodiments, wherein the

Cellulose content is further reduced by the presence of lignin, accessory components from the wood and / or the addition of metallic compounds.

7. Pulp according to at least one of the preceding embodiments, with a xylan content of 9% by weight or more and / or a mannan content of 6% by weight or more.

8. Pulp according to embodiment 7, having a xylan content of 9% by weight or more and a mannan content of 1% by weight or less.

9. Lyocell molded body, produced using the cellulose according to one of embodiments 1 to 8.

10. Lyocell molded articles according to embodiment 9, wherein the molded article is selected from fibers, filaments, staple fibers, nonwoven knitted fabrics, films and powders in spherical shape.

1 1. Lyocell molded body according to at least one of embodiments 9 and / or 10, wherein the molded body is a fiber, a filament or a staple fiber with a cellulose content of less than 90% by weight, a hemicellulose content of more than 5% by weight and a C5 / C6 ratio of 125: 1 to 1: 3, preferably 25: 1 to 1: 2.

12. Lyocell molded body according to at least one of embodiments 9 to 11, the hemicellulose content being more than 10% by weight.

13. Lyocell molded body according to at least one of embodiments 9 to 12, wherein the molded body is a fiber, a filament or a staple fiber with a WRV of greater than 70%, preferably greater than 75%, in particular greater than 80%.

14. Lyocell molded body according to at least one of embodiments 9 to 13, wherein the molded body has a crystallinity of 40% or less.

15. Lyocell molded body according to at least one of embodiments 9 to 14, with a lignin content of more than 0% by weight up to 5% by weight.

16. A method for producing a lyocell molding, comprising the dissolution of a cellulose with a proportion of cellulose of 90% by weight or less and a proportion of hemicelluloses of at least 7% by weight, characterized in that the ratio of those present in the hemicellulose C5 / xylan to C6 / mannan fraction (C5 / C6 ratio) is in the range from 125: 1 to 1: 3, in a suitable solvent, and forming the solution into a lyocell molding.

17. The method according to embodiment 16, wherein the lyocell molding is obtained by a lyocell spinning process.

18. A method for producing a pulp according to any one of embodiments 1 to 8, the method comprising at least one of the following steps:

f) mixing a pure pulp with xylan and / or mannan;

g) treating a pulp with a hemicellulose portion including mannan, by chemical and / or physical processes in order to modify the hemicellulose portion and / or the composition of the hemicellulose contained;

h) production of a pulp using needles and / or hardwoods;

i) mixing a mannan-free pulp with a hemicellulose-rich pulp and optionally subsequent chemical and / or physical treatment of the mixture to adjust the hemicellulose content and / or the composition of the hemicellulose portion;

j) Mixing two pulps with different hemicellulose content and / or hemicellulose composition, and optionally subsequent chemical and / or physical treatment of the mixture to adjust the hemicellulose content and / or the composition of the hemicellulose portion.

19. The method according to embodiment 18, wherein the different pulps are selected from hardwood and softwood-based pulps.