• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
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  • 优先权
    • 专利摘要:
    The present invention describes a novel micro- or nano-scaled cellulosic suspension of the structural type cellulose II. Furthermore, the preparation of this suspension by use of a direct dissolving process and possible applications are described, for example the production of coatings and films by drying.
    公开号:AT511624A1
    申请号:T1609/2011
    申请日:2011-11-02
    公开日:2013-01-15
    发明作者:
    申请人:Chemiefaser Lenzing Ag；
    IPC主号:
    专利说明:

    i «· · · · t t»
    Lenzing AG, PL0506 •
    Cellulose II suspension, the preparation of which was carried out by uhclifarae
    structures
    The present invention describes a novel micro- or nano-scaled cellulosic suspension of the structural type cellulose II. Furthermore, the preparation of this suspension by use of a direct dissolving process and possible applications are described, for example the production of coatings and films by drying.
    State of the art:
    Cellulose powders have been known for some time and are also used in a wide variety of applications - these are usually ground cellulose or so-called microcrystalline cellulose (MCC).
    This is prepared by treating cellulose with acids to dissolve the amorphous portion. Both the conventional cellulose powders and MCC are native cellulose I. Since cellulose is not water-soluble, its applications are sometimes limited. For use in aqueous systems therefore often cellulose derivatives are used, which are obtained by chemical reaction of cellulose. Cellulose derivatives are used, for example, to adjust the viscosity or to impart desired structures to pastes, gels or the like. Also, solutions of cellulose derivatives in drying are partially film-forming and therefore can be used for coating or the like.
    Recently, there is an increased effort to achieve such film and viscosity-forming behavior even with pure cellulose. One reason for this is undoubtedly that there is currently a strong trend towards the use of sustainable, natural materials. For example, there are now innovative, innovative cellulose particles, such as spherical cellulose powders made from regenerated cellulose II. A trend can also be observed in the processing of cellulosic material into very fine structures. By combining acid or enzyme treatment with extreme mechanical treatment processes, cellulose particles with particle sizes at or near the nano-scale can become 1
    Lenzing AG, PL0506 ............ • «« β Μ I «* * *
    «* · T · ·« I i t | 4 · «· · · ·« * »· *« *. As examples here are called vicfibrillated * IVfikrofibrillierte cellulose (MFC) or nanocellulose - Descriptions of these materials can be found for. In Turbak et al., J. Appl. Polymer Sei .: Appl. Polymer Symp. 37 (1983) and Bai et al., Cellulose 16 (2009). Due to the small size of the particles and the large amount of water they require for hydration, these materials form highly viscous gels even at low cellulose concentrations. That such suspensions or gels can also be further processed into films or other shaped articles is also known from the literature.
    Even if viscous and film-forming properties can be achieved with MFC or similar materials, all these methods have some disadvantages. For one, this is the considerable expense of production. In order to actually achieve the required fineness, it is necessary to separate the existing cellulosic structures. Mechanical treatment is not sufficient, which is why other treatment steps must be upstream. These serve to weaken the cohesion between the cellulose chains and thus allow comminution to the desired scale. A common method here is the oxidation by means of TEMPO radical as described, for example, in Besbes et al., Carbohydrate Polymers 84 (2011). Another method describes US 2011/0036522 A1, namely the treatment of the cellulosic starting material with amphoteric cellulose derivatives.
    Here, for the sake of completeness, bacterial cellulose (BC) should also be mentioned. This can already be grown as a hydrogel, but this process is by no means easy and inexpensive. In addition to the elaborate production is another disadvantage that sometimes form brittle, brittle films in the formation of films from such cellulosic suspensions or gels, which in turn restricts their use. Here again, solutions are already to be found in the literature. For example, DE 10 2008 034 281 A1 describes the addition of plasticizers to the cellulose gel in order to make the resulting film more flexible.
    As the name implies, microfibrillated cellulose, but also all other types of nanocellulose, are in fibrous form. The preparation takes place in that portions of the existing fibers are peeled off, 2 * ·······················································.
    Lenzing AG, PL0506 after weakening the bonds between the molecules. This fibrous structure is described throughout the literature and formed from such cellulose suspensions molded bodies still have a fibrous fine structure.
    Cellulose II has already been mentioned above. This is the type of cellulose that forms when dissolving and reprecipitating cellulose. The difference between cellulose I and II lies in the crystal structure (= arrangement of the macromolecules), whereby cellulose II is the thermodynamically more stable structure. The advantage of dissolving and subsequent precipitation of cellulose is that it gives rise to various possibilities for shaping and modification. Particularly advantageous are so-called direct dissolving processes, in which the cellulose is dissolved without prior chemical derivatization in suitable solvents. The most popular direct dissolving process is the lyocell process, which uses aqueous NMMO as a solvent. This process is also used on an industrial scale for the production of fibers. In addition, many other solvent systems which are suitable for this purpose, such as, for example, LiCl-DMAc, are known to the person skilled in the art. US 2009/0308552 already describes microfibrillated cellulose of the structural type II. However, conventionally prepared MFC has already been converted by means of treatment with sodium hydroxide solution to cellulose II, whereby of course the fiber structure of the suspended particles is also retained. W02009 / 036480 A1 describes, for example, the preparation of spherical cellulose particles starting from cellulose / NMMO solutions. However, these powders are dry and give only limited gels when resuspended in water. Above all, a drying of such suspensions does not lead to the desired closed film, but to brittle granular layers.
    Task:
    Compared to this prior art, the object was to develop novel cellulosic suspensions or gels with novel properties, as well as to provide a process for their production which, in comparison to already existing processes, has a 3 *
    Lenzing AG, PL0506 simplified manufacturing process. At the same time, however, the properties of the gel or of the cellulose suspension should be able to be varied over a wide range and it should be possible to produce films or coatings with improved properties, such as greater flexibility. Also, the suspensions should be suitable for different applications. Solution:
    The solution according to the invention of the abovementioned problem was achieved by dissolving cellulose in a direct solvent, subsequent reprecipitation of the cellulose and subsequent appropriate work-up. This workup is preferably chosen so that it can be done in a single step with simple aggregates. By varying the process parameters, the properties of the suspension or of the gel can be adapted to different requirements. The resulting cellulosic suspension differs from the already known materials (such as MFC) in that the cellulose particles contained therein do not have a purely fibrous form but are largely isotropic. In addition, these (isotropic) particles are highly porous and swollen, forming a loose network. In the following, the process for preparing the suspensions of the present invention and the processing of the obtained materials (e.g., films) are described in detail and by way of examples.
    The invention relates to a novel cellulosic suspension, wherein the cellulose particles are present in the structural type II. Contrary to the known state of the art, the cellulose is present not only in the form of very fine fibers, but as largely isotropic particles with only a low L / D ratio. Furthermore, the particles contained in the suspension are highly porous and heavily swollen. The fine primary particles form network-like structures among each other. Due to the high water binding capacity of the cellulose particles, the suspension is highly viscous even at low solids content and forms a homogeneous gel. 4 * «* * * * * * * * * * * * * * * * *« «* * * * * * * * - * ls M ··· ··
    Lenzing AG, PL0506
    In particular, the present invention is a cellulosic suspension containing 0.01 to 20 wt.%, Preferably 0.1 to 10 wt.% Cellulose, wherein the cellulosic material was never dried during its preparation.
    The cellulosic material may contain from 1 to 200% by weight, based on the amount of cellulose, of incorporated additives selected from the group comprising pigments, titanium oxides, in particular substoichiometric titanium dioxide, barium sulfate, ion exchangers, polyethylene, polypropylene, polyesters, activated carbon, polymeric superabsorbents, cellulose derivatives, other biopolymers (such as chitosan or starch) and flame retardants.
    In a further embodiment, the cellulosic material may also contain over 200% by weight, up to 1000% by weight of additives. The cellulosic material in such an embodiment acts as a binder or carrier.
    Another object of the present invention is therefore also a material formed from the cellulose gel according to the invention and additives in an amount of 200 to 1000 wt.% Based on the amount of cellulose, wherein the cellulose acts as a binder or carrier substance.
    The invention further consists in a method for producing the cellulosic suspension already described starting from a solution of underivatized cellulose by means of direct dissolving method. The cellulose concentration in the solution is chosen so that the cohesion between the cellulose chains is weakened so much that the subsequent comminution can be made with little effort.
    Preferably, the solvent used (system) contains an organic substance, here again preferably selected from the group amine oxides, in particular N-methylmorpholine-N-oxide. Also preferably, the solvent system contains a certain amount of water. Such compositions are generally known to the person skilled in the art. 5 • · · · · · * * * ♦
    Lenzing AG, PL0506
    For this purpose, a cellulose with low cellulose concentration is dissolved in a suitable solvent, the cellulose concentration should be well below the (depending on the particular solvent system) maximum soluble concentration. This ensures that the cellulose molecules are sufficiently separated to be processed later to the gel of the invention can. Already in the cellulose solution suitable additives (see above) can be introduced. The cellulose solution is now regenerated by introduction into a suitable regeneration medium - in NMMO z. As water or a water / NMMO mixture. The cellulose is already coarsely crushed, either simply by means of an agitator or by suitable aggregates (eg granulator). By means of suitable washing steps, the solvent is removed. This can be done batchwise or continuously. After this step, the cellulose is in the form of wet "granules" in water.
    Another way to get to this precursor for the cellulosic suspension according to the invention, is to cool the solution freely flowing below its solidification temperature and to comminute the solidified cellulose solution into granules. The solvent is then washed out and again a highly swollen cellulose granulate in water,
    It is important that the washed out, never dried granules from this stage is not dried too much, which would cause a collapse of the structure and thus no suspension according to the invention results. Although a portion of the water may be removed for ease of handling, the cellulosic material should always have a moisture content of at least 50%, preferably at least 100% and most preferably at least 150%.
    The moist cellulose granules are ground to a suspension in a comminution step, preferably a wet grinding. This suspension, as well as the precursor materials (solidified cellulose solution, the granules before and after washing out) should also be referred to as "cellulosic material" for the purposes of the present invention. 6
    Lenzing AG, PL0506 ·. / ........ * **
    The comminution of the starting material to the final suspension preferably takes place in the circulation, the cellulose content being in the range between 0.1% by weight and 20% by weight. Even during comminution, additives can be added to the cellulosic suspension. The crushing is done with suitable aggregates such as cone mills, refiners or grinding media mills.
    This final comminution step is also suitable for introducing additives. In this case, it is also possible to introduce those additives which, for example, are not stable in the cellulose solution initially present. The additives can be easily introduced into the comminution process and are thus distributed homogeneously in the suspension.
    The invention also relates to the use of the cellulose suspension for the production of cellulose layers.
    The cellulose layers in a preferred embodiment are films or coatings of other bodies.
    The coatings can be closed, for example packaging films or food coatings or incomplete coatings, for example binders for nonwovens or other materials, wherein the adhesion effect is achieved by drying and formation of hydrogen bonds.
    In such a use of the cellulosic suspension according to the invention, the other material is preferably present in a proportion of from 200 to 1000% by weight, based on the amount of cellulose.
    Especially in nonwovens or similar open structures, the cellulosic suspension of the invention can be applied so that the entire structure is penetrated by the cellulosic suspension and not only superficially coated. This again leads to a significant increase in the strength of the resulting composite material over the original structure. 7
    Lenzing AG, PL0506
    If closed layers are formed with the cellulosic suspension according to the invention, these act as barrier layers due to their dense, closed structure. For example, it is well known that cellulose films have only a very low permeability to oxygen. The cellulosic layers may be formed by spraying, knife coating or brushing and / or by evaporation of the aqueous phase and / or additional operations such as heating or pressing, in particular for film formation.
    In addition to the production of films or coatings, the production of other moldings from the cellulosic suspension according to the invention is possible, for example by extrusion or by the use of suitable molds. For this purpose, it is advantageous to use the cellulosic suspension as highly concentrated as possible or to add suitable additives.
    The cellulosic suspension can also be used as a viscosity modifier. The highly swollen cellulose particles bind a large amount of liquid and thus have a thickening effect. Depending on the production parameters, the amount of bound water and thus the thickening effect can be adjusted.
    By adding additives during the different stages of production, further functionalities can be introduced into the cellulosic suspension. It can also produce hybrid materials.
    Likewise, the cellulosic suspension can be used as a starting material for the production of dried cellulose powder.
    Depending on the solvent or solvent system, the amount of cellulose that can be dissolved varies. Other parameters of the process control such as temperature or the cellulose used itself (purity or degree of polymerization) influence this value.
    Normally, for reasons of economy, attempts are made in large-scale processes to dissolve as much cellulose as possible. The solved 8
    Lenzing AG, PL0506 • * ** »« * • · »•« »M · *» »· · > * * M **
    Cellulose can now be precipitated again and thereby brought into various forms such as fibers or films. For the present invention, however, the cellulose is precipitated as far as possible without distortion or shear, so that no or only a few fibrous structures can form. The exact procedure is described in W02009 / 036480 A1. The cellulose is comminuted and cleaned of solvent and is then present as granules. It is important that the cellulose granulate is not dried, but is always surrounded with enough water, so in so-called "never dried" form. The dissolution and subsequent precipitation of the cellulose are the first steps in the preparation of the cellulosic suspension according to the invention.
    The next step is the comminution of the never dried granules in a suitable wet process. Suitable commercially available comminuting units are, for example, refiners, conical mills or Ultra-Turrax, but other apparatus or methods are also possible in principle. So aggregates with very high energy input such as stirred ball mills or high-pressure homogenizers can be used. In order to process the cellulosic material with these devices, but usually a pre-crushing is necessary. Optionally, the crushing of the cellulose can also be accelerated by an appropriate pre-treatment - z. B. enzymatically or chemically (acid, etc.). The comminution can either be carried out in a continuous pass-through step or else by the corresponding unit being circulated for a suitable period of time. In the course of this work-up step, the cellulose granules are comminuted, whereby the suspension thickens and a gel-like mass is formed.
    It has surprisingly been found that the structure of a cellulose suspension clearly depends on the nature of the starting material used (cellulose granules), and this in turn on the cellulose concentration in the solution before forming the granules. At a cellulose concentration above a " transition concentration " in 9
    Lenzing AG, PL0506 • · • · «· · •« • * * ·
    , * ............ the solution before regeneration is obtained by the method according to the invention, a suspension consisting of macroscopically detectable in a light microscope particles. This suspension is also characterized in that it has a significantly lower water retention capacity compared to a suspension formed from a solution below the "transition concentration". Also, it is not so viscous and sedimented at lower concentrations. By contrast, at a cellulose concentration below the "transition concentration", a suspension in which macroscopically no particles can be detected is obtained by the method according to the invention. This means that the structure of the individual particles can no longer be sufficiently resolved in a light microscope - the suspension appears to be largely homogeneous. On the other hand, light scattering is not suitable for determining the particle size. Since the primary particles also form network-like structures, significantly larger particles are simulated in light scattering measurements, but they are not found under the microscope. Such suspensions are very uniform and feel like z. B. when rubbed between the fingers "smooth" and there is no sedimentation even at low cellulose concentrations.
    Common to the cellulosic suspensions formed is that they are highly viscous and have a gelatinous appearance. However, the suspensions prepared from higher concentration solution require a higher solids content to actually come to a gel-like structure. At lower solids content, there is still a sedimentation of cellulose particles and it forms a supernatant of water. Only when enough water is bound by the particles (from ~ 10% cellulose), a uniform suspension is formed, which also no longer sediments.
    In contrast, suspensions of dilute solution already have a significantly lower solids content in order to obtain a highly viscous gel. Already at solids contents below 2% by weight, separation no longer occurs since the water requirement of the fine cellulose structures is correspondingly high. 10
    Lenzing AG, PL0506
    Depending on the application, it may now be advantageous to use different types of cellulosic suspensions. In general, they are suitable for structure formation or adjustment of the viscosity in aqueous systems, with more or less cellulose being present in the system, depending on the system. Such structural or viscosity adjustments while retaining larger amounts of water are for example in the food or cosmetics of interest. Also here additional substances can be introduced via the cellulose gels as a carrier.
    Another area where high water retention in combination with the viscosity effect can provide benefits is in the field of building applications. For example, some types of mortar, such as thin-bed mortar or plaster, should not release the moisture to the environment too quickly to allow a crack-free hardening of the mortar. Furthermore, it is important for these mortars that they show an optimal, uniform coating behavior due to their Theological nature.
    Further possible fields of use for the cellulosic suspensions are those as binders as shown in FIG. 3. The suspensions can be adjusted so that they can still be applied well (such as by spraying) -. B. liquid enough to penetrate into spaces. Upon drying, hydrogen bonds probably form between the fine cellulosic structures and the appropriate substrate, providing some cohesion. This "adhesive effect" can also increase the strength of materials such as cardboard or paper. At the same time the density is increased and thus the permeability is lowered. It creates a barrier functionality. Depending on the type of application, these effects can be selectively controlled as illustrated in Example 3. In addition to cardboard or paper, for example, nonwovens or other nonwovens can be solidified.
    Since the cellulose is very finely divided, the suspensions tend to film formation during drying. This behavior was already used in the coating of a pulp sheet described in the above example. In this case, the coating is fixed to the (chemically similar) 11 • · * * • * • «k«
    Lenzing AG, PL0506 • * · *** »· · · *
    Pad connected. By suitable methods, however, the films can also be produced in such a way that they are present in separated form. This will be clarified with reference to Example 4.
    As stated, films and coatings, which are likewise the subject of this invention, can be formed from the cellulosic suspensions according to the invention. The films differ significantly depending on which suspension they are formed from. Thus, the films are not transparent from a suspension of highly concentrated dope and still have a clearly recognizable structuring. However, compared to structures formed from fibrous cellulosic materials of comparable size, these films tend to be film-like rather than paper-like.
    This film-like character is even more pronounced in films made from suspensions of dilute spun mass. Even simple drying without the addition of additives leads here to transparent films, which also withstand easier mechanical stress, since they are not too brittle. As shown in Example 4, these films are very uniform and compact. This results in a cellulose film that is partially comparable to known, extruded cellulose films. By adding additives to the cellulosic suspension in different stages of production as already described, it is of course also possible to influence the properties of the films formed. Especially for the purpose of film formation, wet strength agents or plasticizers may be added to the cellulosic suspensions; it is also possible to crosslink the cellulose molecules in the film. The fact that this film but forms from suspension and thus can be applied as by spraying or brushing, there are quite a few new applications - for example, "paints" or similar coatings of various materials based on cellulose as a binder possible.
    A particular advantage of the cellulosic suspensions according to the invention is the possibility of spraying them into layers. Applications for such 12 »·» *
    Lenzing AG, PL0506 ....... * ..... sprayed coatings are for example films for agriculture, which can easily be incorporated into the soil after use. Another application would be the use as a spray plaster or -Verband. A combination of cellulose and chitosan (for improved wound healing) would also be well suited for this purpose.
    The suspension can also be applied to foods such as fruits and vegetables, whereby the film, which forms directly on the surface, acts as a cling film. Namely, water vapor can diffuse through the cellulose film while being a barrier to oxygen. Similarly, for example, the cut surfaces of suitable foods can be treated.
    As described above, the cellulosic suspensions according to the invention preferably form compact film-like structures on drying. This is due to the formation of hydrogen bonds between the present cellulosic structures. Due to the fineness of these structures, this tendency to form compact layers is so pronounced that simple drying of the suspensions or gels according to the invention in order to obtain separated particles is not possible. However, there are methods that allow drying of such materials, such as freeze drying or spray drying.
    Spray drying is also suitable for producing a wide variety of particle structures. Thus, aggregates or agglomerates are possible in addition to individual compact particles. Spray drying also offers the possibility of producing hybrid particles. The additives can be introduced into the cellulosic suspension already during production (as explained above) or can only be metered in during the spraying process.
    Also, an exchange of the aqueous phase for an apolar solvent allows drying, since the strength of the
    Hydrogen bonds is reduced upon removal of the solvent. When choosing a suitable solvent can then be dried with supercritical CO2. As a result, not only the particles remain separated, but also the inner surface is retained and so-called aerogels are created. 13
    Lenzing AG, PL0506 • r · ♦ * · * k
    Another way to obtain redispersible particles that form gels again is to use suitable protective colloids in drying. This produces agglomerates that are significantly larger than the original primary particles. Since excessive binding between the cellulose particles is prevented by the protective colloids, they are redispersible again. Depending on the application, such larger agglomerates may be advantageous - eg. B. because larger particles are generally easier to dose than very fine particles.
    Finally, some examples of the use of the cellulosic suspensions according to the invention are given below. By coating or incorporating textiles or nonwovens of synthetic fibers with the cellulosic suspensions, their hydrophilicity can be improved. Compared to cellulosic fibers (such as cotton or regenerated fibers), synthetic fibers can absorb little or no water. For certain applications, a hydrophilic finish of synthetic fibers is therefore an advantage. If this is achieved by the cellulose gels according to the invention, the result is a more pleasant handle.
    Recently, the literature increasingly describes nanomaterials for plastic reinforcement, including very fine cellulose particles. An example of this can be found in Qu et al., BioResources 5 (2010). Also suitable for this invention are the cellulosic suspensions. Both the original suspensions and the dried particles can be used.
    Examples:
    The invention will now be explained by way of examples. These are to be understood as possible embodiments of the invention. By no means is the invention limited to the scope of these examples.
    Example 1:
    From a prepared according to the prior art NMMO spin mass having a cellulose content of 13 wt .-% was a 14
    Lenzing AG, PL0506 ... · ·: ** ·, * ·. :; :: * * "*::;; .......". ......... *
    Cellulose granules produced. The never dried granules were suspended in water and comminuted with a cone mill IKA MK 2000/4 (IKA Werke, Staufen). The grinding was done in the circulation at a speed of 12,000rpm with a minimum gap (150pm) for 90 minutes. The cellulosic suspension to be ground contained in an experiment 4% by weight of cellulose and in a further experiment 9% by weight of cellulose. Up to 4% by weight of cellulose content exceeded the own pumping power of the mill. In addition, an external pump had to be used to maintain the circulatory flow since the viscosity of the suspension was much higher. As the milling time progressed, the suspension thickened to form a viscous, gel-like mass. When rubbed between the fingers but were still noticeable particles. Even under an optical microscope (Olympus BX 51) were still clearly particles visible - see Fig. 1. A particle size measurement by laser diffraction (device Sympatec Helos) revealed an average particle size χ50 = 218μιτ) (xgo = 594pm).
    In addition, the water retention capacity (WRV) of the cellulose particles was determined. For this purpose, a defined amount of suspension in special centrifuge tubes (with drain for the water) was introduced. Thereafter, spin-off was carried out at 3000 rpm for 15 minutes and the wet cellulose was weighed immediately afterwards. The wet cellulose was dried for 4 hours at 105 ° C and then determined the dry weight. The WRV was calculated according to the following formula: WRV [%] - (mrmt) / m * 100 (mf mass wet, mt = dry mass)
    The results are summarized in Table 1.
    Example 2:
    Again, never dried cellulose granules were ground from NMMO solutions using an IKA MK 2000/4 cone mill. The milling was again carried out at the smallest grinding gap (150pm) for 90 minutes at 12,000rpm. In contrast to Example 1, however, no spinning material with 13% by weight was used as the starting material, but 15
    Lenzing AG, PL0506:: *:: ··· .:: •; ; mit ····· Solutions with lower cellulose concentrations. The cellulose concentrations used were 5% by weight, 3% by weight and 2% by weight.
    When processing granules from a 5 wt .-% solution, the result was comparable to that described in Example 1. The highly viscous suspension still contained clearly noticeable particles that could be detected under the microscope (Olympus BX 51) and by laser diffraction (χ5ο = 65μΓη, X90 = 180pm). Surprisingly, no particles were found in the gels prepared by milling from 2% strength by weight and 3% strength by weight solution. Under an optical microscope 10 particles could no longer be resolved. To get an impression of the existing structures, a drop of the suspension of the 2 wt .-% cellulose solution was placed on a sample carrier for the electron microscope and then frozen in liquid nitrogen. Thereafter, the sample was evacuated and steamed with gold. The recording was carried out with a Hitachi S-4000 electron microscope at 10 kV acceleration voltage, Fig. 2 shows such a recording. Also from these suspensions the WRV was determined. The results are also found in Table 1. 16
    Lenzing AG, PL0506
    Table 1: Properties of gels from Examples T and 2 * '
    Starting material Cellulose content in suspension [% by weight] WRV [%] Dope 13% by weight Cellulose 4.5 215 Dope 5% by weight Cellulose 3 575 Dope 3% by weight Cellulose 2.3 735 Dope 2% by weight Cellulose 1.8 850
    EXAMPLE 3 The influence of the workup on various substrates already described in the above examples was investigated, in particular whether suspensions according to the invention can also be prepared therefrom. The following raw materials were used: • Never dried cellulose granules of 13% cellulose 10 • Never dried cellulose pulp of 2% cellulose • Never dried 30dtex Tencel ribbon fibers
    First, the pulp was ground by means of IKA MK 2000/10 to determine the grinding parameters. The cellulose content in the milling was 2w% and the grinding time again at 60 minutes. However, the grinding gap could not be set to the minimum, but had to be left at 20 250pm. The remaining three materials were ground with identical settings.
    Already visually, the materials obtained were very different. The milling of the moist cellulose granules led to the suspensions already described above. The suspensions of fibers and pulp differed significantly: both showed clearly fibrous structures, some of which were also knotted into lumps. After 17
    Lenzing AG, PL0506 of the method already described above, cias WRV of the four suspensions was determined - the results are summarized in Table 2.
    Table 2: Properties of the suspensions from Example 3
    Starting material WRV [%] Dope 13% by weight Cellulose 255 Dope 2% by weight Cellulose 860 Ribbon fiber 30dtex 270 Pulp Saiccor 180 5
    Example 4:
    Each 6g of a long fiber pulp were pitched and formed from leaves. For some of these leaves, 5% by weight of the pulp 10 was replaced by an amount of the suspension of Example 2, which was prepared in an amount equal to 2% by weight, based on the cellulose contained, and leaves were also formed therefrom. Another part of the pure pulp sheets was also coated after drying with the cellulosic suspension of Example 2 by knife coating. On the 15 air-dry leaves both the strength (by Zwick Roell 1120) and the air permeability (according to DIN EN 9237) were measured. In each case 5 measurements were carried out here and the mean values were formed. The results are summarized in Table 3. The sheets were supplemented by electron micrographs (Hitachi S-4000 with 20 10 kV acceleration voltage). Fig. 3 shows an overview of the sheet with added suspension and Fig. 4 shows the coated sheet (transition from coated to uncoated area).
    Example 5: 25 The suspension from Example 2, prepared from 2% by weight spinning composition, was applied by means of a doctor blade to various substrates: glass, PP, PTFE and paper. Thereafter, the suspension was allowed to air dry - the following films were formed: 18 * · · ·
    Lenzing AG, PL0506 * · »· *
    Glass: The result was a transparent homogeneous film over the entire surface. However, the film could not be detached from the glass surface without completely destroying it. PP: Once again, a transparent homogeneous film was formed during drying, but it was partially torn and curled on the edge (thicker areas). Starting from these points, small pieces (a few cm 2) of the film could be peeled off. But even here no complete separated film could be obtained. PTFE: The film here had a similar shape to PP as described above. However, the film was carefully removed from the base and could be further investigated.
    Paper: This resulted in a continuous homogeneous coating, which was firmly bonded to the substrate (as in Example 3 on the pulp sheet). Compared to uncoated paper, the coated was smoother and showed a higher gloss.
    Using an optical microscope (Olympus BX 51 equipped with a digital camera), the thickness of the film removed from the PTFE substrate was determined to be about 13 μm. The film itself appeared completely homogeneous in the optical microscope and no structures could be resolved. Therefore, the film was additionally observed by electron microscope (Hitachi S-4000 with 10 kV accelerating voltage). Fig. 5 shows such a recording. The film is very consistent and has minimal irregularities. 19
    Lenzing AG, PL0506
    Table 3: Properties of the layers of Examples 3 and 4
    Sample elongation [%] Working capacity [J / m 2] Tear length [m] Air permeability [l / m 2] Long-fiber pulp 1.45 8.9 338 26 Long-fiber pulp + 5% by weight Cellulose Gel 1.19 14.1 638 16 Long-fiber pulp Cellulose gel laces 0.84 7 443 <5 20
    权利要求:
    Claims (21)
    [1]
    Lenzing AG, PL0506 Claims: 1. A process for the preparation of a cellulose gel from a solution of underivatized cellulose in a mixture of an organic substance and water, characterized in that the solution is cooled freely flowing below its solidification temperature, the solidified cellulose solution comminuted into granules is washed, the solvent is washed out and the washed out, never dried granules in a second crushing step, preferably a wet grinding, is ground to a suspension having a particle size (X50) between 1 and 50 pm.
    [2]
    2. A method according to claim 1, wherein the cellulose solution before cooling has a cellulose concentration below the limit for formation of particulate gels.
    [3]
    3. A method according to claim 1, wherein the cellulose solution before cooling has a cellulose concentration between 0.01% by weight and 5% by weight.
    [4]
    4. The method of claim 1, wherein the suspension in the second crushing step has a cellulose content of between 0.5% and 20% by weight.
    [5]
    5. The method according to claim 1, wherein the suspension is recycled in the second crushing step.
    [6]
    6. The method according to claim 1, wherein the cellulosic material always has a humidity of at least 50%, preferably of at least 100% and more preferably of at least 150%.
    [7]
    7. A process according to claim 1, wherein either the cellulose solution prior to cooling or the cellulosic material during a comminution step comprises from 1 to 200% by weight of additives based on the amount of cellulose selected from the group comprising pigments, titanium oxides, in particular substoichiometric Lenzing AG , PL0506

    Titanium dioxide, barium sulfate, ion exchangers, polyethylene, polypropylene, polyester, activated carbon, polymeric superabsorbents and flame retardants may be added.
    [8]
    8. The method according to claim 1, wherein the organic substance is an amine oxide, preferably N-methylmorpholine-N-oxide.
    [9]
    A cellulose gel prepared by the process of claims 1 to 8.
    [10]
    10. Cellulose gel containing 0.01 to 20 wt .-%, preferably 0.1 to 10 wt .-% cellulose, characterized in that the cellulosic material was never dried during its preparation.
    [11]
    11. The cellulose gel according to claim 10, wherein the cellulosic material contains 1 to 200% by weight, based on the amount of cellulose, of additives selected from the group comprising pigments, titanium oxides, in particular substoichiometric titanium dioxide, barium sulfate, ion exchangers, polyethylene, polypropylene, polyesters , Activated carbon, polymeric superabsorbents and flame retardants.
    [12]
    12. Use of the cellulose gel according to claim 10 for the production of cellulose layers.
    [13]
    Use according to claim 12, wherein the cellulose layers are films or coatings of other bodies.
    [14]
    14. Use according to claim 13, wherein the coatings are closed or incomplete coatings.
    [15]
    Use according to claim 12, wherein the cellulose layers are formed by spraying, knife coating or brushing
    [16]
    Use according to claim 12, wherein the cellulose layers have barrier properties.
    [17]
    17. Use of the cellulose gels according to claim 10 as a binder for other materials, wherein the adhesion effect is achieved by drying and formation of hydrogen bonds. 22 Lenzing AG, PL0506 ............ «. · · · * ** · · «« «« «· · · ·, t« · «· · · * * * * ··· ·· * · * ·· * · *
    [18]
    18. Use of the cellulose gels according to claim 17, wherein the other material is a non-wovens structure whose strength is thereby increased.
    [19]
    19. The use of the cellulose gels according to claim 17, wherein the other material is present in a proportion of from 200 to 1000% by weight, based on the amount of cellulose.
    [20]
    20. Use of the cellulose gel according to claim 10 for the production of dried cellulose powder.
    [21]
    21. The dry cellulose powder according to claim 20 prepared by spray-drying. 23
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    AT10242011|2011-07-13|
    ATA1609/2011A|AT511624B1|2011-07-13|2011-11-02|CELLULOSE II SUSPENSION, THEIR PREPARATION AND STRUCTURES MADE THEREFROM|ATA1609/2011A| AT511624B1|2011-07-13|2011-11-02|CELLULOSE II SUSPENSION, THEIR PREPARATION AND STRUCTURES MADE THEREFROM|
    CN201280034689.9A| CN103649178B|2011-07-13|2012-07-12|The structure of cellulose II suspension, its preparation and formation thereof|
    PCT/AT2012/000186| WO2013006876A1|2011-07-13|2012-07-12|Cellulose ii suspension, production thereof and structures formed therefrom|
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