Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
  • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
  • C08J3/075—Macromolecular gels
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
  • C08J3/122—Pulverisation by spraying
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/016—Flame-proofing or flame-retarding additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D101/00—Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
  • C09D101/02—Cellulose; Modified cellulose
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J101/00—Adhesives based on cellulose, modified cellulose, or cellulose derivatives
  • C09J101/02—Cellulose; Modified cellulose
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
  • C08J2301/02—Cellulose; Modified cellulose
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
  • C08L2205/16—Fibres; Fibrils

Definitions

• the present invention describes a novel micro- or nanoscale cellulosic suspension of the structural type cellulose II
• 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).
• MMC microcrystalline cellulose
• Cellulose can be obtained.
• Cellulose derivatives are used, for example, to adjust the viscosity or to impart desired structures to pastes, gels or the like.
• solutions of celulose derivatives in drying are partially film-forming and therefore can be used for coating or the like.
• Viscosity modifier added as a component can be natural products such. Carrageenan, AgarAgar, starch or chelatine. Synthetic products often consist of mixtures of cellulose powder
• Celiulose derivatives such. B. carboxymethylcellulose or
• Suspensions or gels can also be further processed into films or other shaped bodies, is also known from the literature.
• bacterial cellulose should also be mentioned.
• This can already be grown as a hydrogel, but this process is by no means easy and inexpensive.
• brittle films are formed, which in turn limits their application.
• solutions are already to be found in the literature.
• DE 10 2008 034 281 A1 describes the addition of plasticizers to the cellulose gel in order to make the resulting film more flexible.
• microfibrillated cellulose but also all other types of nanocellulose, are in fibrous form.
• the preparation is done by peeling off the existing fibers 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.
• 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.
• WO2009 / 036480 A1 describes, for example, the production of
• Coatings with improved properties, such as higher flexibility, can be produced. Also, the suspensions should be different
• This workup is preferably chosen so that it can be done in a single step with simple aggregates.
• Suspension or the gel can be adapted to different requirements.
• the resulting cellulosic suspension differs from the already known materials (such as MFC) in that it contains contained Celluiosepumble no purely fibrous form, but are largely isotropic. In addition, these (isotropic) particles are highly porous and swollen, forming a loose network.
• the process for the preparation of the suspensions according to the invention and the further processing of the resulting materials are described in detail and by way of examples.
• the invention relates to a novel cellulosic suspension, wherein the Celluiosepumble 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.
• 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
• Celluiosep the suspension is highly viscous even at low solids content and forms a homogeneous gel.
• the subject of the present invention is a
• Cellulose suspension containing 0.01 to 20 wt.%, Preferably 0.1 to 10 wt.% Cellulose, wherein the cellulosic material during its
• the cellulosic material may be 1 to 200% by weight, based on the
• Amount of cellulose 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.
• 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.
• the cellulosic material may also contain over 200% by weight up to 000% by weight of additives.
• the cellulosic material acts in such an embodiment as a binder or
• Another object of the present invention is therefore also a
• 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.
• 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.
• 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.
• an organic substance here again preferably selected from the group amine oxides, in particular N-methylmorpholine-N-oxide.
• the solvent system contains a certain amount of water.
• compositions are generally known to the person skilled in the art.
• 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.
• suitable additives see above
• 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 an agitator or by suitable aggregates (eg granulator).
• 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.
• the solution is free-flowing To cool below its solidification temperature and to crush the solidified cellulose solution into granules. Subsequently, the solvent is washed out and gives again a highly swollen cellulose granules 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.
• 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 into a suspension in a comminuting 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.
• 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. Also during the crushing can the
• Cellulose suspension can still be added additives.
• 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.
• additives which, for example, are not stable in the cellulose solution initially present.
• the additives can easily be used in the comminution process
• 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 by drying and formation of
• Cellulose suspension the other material in a proportion of 200 to 1000 wt, -%, based on the amount of cellulose before.
• Cellulose suspension according to the invention are 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.
• cellulose films have only a very low permeability to oxygen.
• the cellulose layers can be obtained 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, to be formed.
• additional operations such as heating or pressing, in particular for. Film formation, to be formed.
• cellulose suspension As 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.
• Manufacturing parameters can be set the amount of bound water and thus the thickening effect. Surprisingly, the
• the cellulosic suspensions according to the invention can thus be used for many purposes, for example as thickening agents for foods or cosmetics.
• the cellulosic suspension can be used as a starting material for the production of dried cellulose powder.
• Process control such as temperature or the cellulose used itself (purity or degree of polymerization) influence this value.
• Cellulose granules are not dried, but always with sufficient water is surrounded, that is present in so-called “never dried” form Dissolution and subsequent precipitation of the cellulose represent 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.
• Shredders are, for example, refiners, cone mills or Ultra-Turrax, but other devices or processes are also possible. So can also aggregates with very high energy input such as
• Agitator ball mills or high-pressure homogenizers are used. In order to process the cellulosic material with these devices, but usually a pre-crushing is necessary. Optionally, the crushing of the cellulose by a corresponding
• Pretreatment be accelerated - 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.
• the cellulose granules are comminuted, whereby the suspension thickens and a gel-like mass is formed.
• Cellulose concentration in the solution before forming the granules depends.
• the process according to the invention gives a suspension which consists of particles which can be detected macroscopically in a light microscope
• suspensions of dilute solution already have a significantly lower solids content in order to obtain a highly viscous gel.
• solids contents below 2% by weight, no separation occurs, since the water requirement of the fine cellulose structures is correspondingly high.
• Such structural or viscosity adjustments while retaining larger amounts of water are for example in the food or cosmetics of interest.
• additional substances can be introduced via the cellulose gels as a carrier.
• 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) -.
• 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, while at the same time increasing density and thus increasing the strength of the material
• 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.
• Cellulose suspensions form films and coatings which are also the subject of this invention.
• the films differ significantly depending on which suspension they are formed from.
• the films of a suspension of highly concentrated dope are not transparent and still have a clearly recognizable structuring on.
• 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.
• these films are very uniform and compact. This results in a cellulose film which is partially comparable with known, extruded cellulose films.
• Cellulosic suspensions nor wet strength agents or plasticizers are added; it is also possible to crosslink the cellulose molecules in the film.
• 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 sprayed layers include, for example, agricultural films which, after use, can easily be incorporated into the soil.
• 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 like a cling film. Namely, water vapor can diffuse through the cellulose film while being a barrier to oxygen.
• the cut surfaces of suitable materials such as fruits and vegetables, whereby the film, which forms directly on the surface, acts like a cling film. Namely, water vapor can diffuse through the cellulose film while being a barrier to oxygen.
• Cellulose suspensions on drying preferably prefers compact film-like structures. 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
• cellulosic suspensions 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 too
• Regeneratfasern synthetic fibers can absorb little or little water.
• 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.
• the grinding was carried out in the circulation with a
• the cellulosic suspension to be admired contained 4% by weight in one experiment.
• the water retention capacity (WRV) of the cellulose particles was determined. This was a defined amount of suspension in special
• Example 2 Grinding took place again with the smallest grinding gap (150 pm) for 90 minutes at 12,000 rpm in the circulation. In contrast to Example 1, however, no spinning mass with 13 wt .-% was used as starting material, but solutions with lower cellulose concentrations. The used
• Example 2 prepared from 2 wt .-% pure dope, 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:
• the film had a similar shape as above,
• Paper This resulted in a homogeneous 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.
• the thickness of the withdrawn from the PTFE substrate film was determined with about 13 ⁇ .
• FIG. 6 shows the dependence of the shear viscosity on the shear rate for the cellulose suspensions of various concentrations according to the invention.
• FIG. 7 shows a comparison with the 25% Vivapur suspension from Example 6.

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• Chemical Kinetics & Catalysis (AREA)
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• 2011
  • 2011-11-02 AT ATA1609/2011A patent/AT511624B1/de active
• 2012
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