KR100451083B1 - Method For Preparation Of Highly Homogeneous Cellulosic Solution With Neader - Google Patents

Abstract

The present invention relates to a method for producing a highly homogeneous cellulose solution using a kneader, injecting cellulose powder and liquid concentrated NMMO at the same time into the kneader, and then swelling the cellulose into a paste without decompression process in the kneader, and then using an extruder. It is characterized by a method of supplying and dissolving in a homogeneous state and extruding through a spinneret, and can be produced homogeneous cellulose solution immediately in the dissolution manufacturing process without a separate swelling process in the vacuum distillation process and the extruder. A more homogeneous solution can be prepared in a shorter time.

Description

Method for Preparation of Highly Homogeneous Cellulosic Solution With Neader

The present invention relates to a method for preparing a high homogeneous cellulose solution using N-methylmorpholine N-oxide (hereinafter referred to as "NMMO") as a solvent in the preparation of cellulose fibers or films, and more specifically, NMMO By improving the swelling process of the cellulose used to increase the dissolution rate of cellulose and to reduce the amount of undissolved cellulose it relates to a method for producing a highly homogeneous cellulose solution.

Cellulose fiber and film manufacturing process using NMMO solvent has been widely used in the manufacturing process of cellulose-based products due to the pollution-free process according to the recovery and reuse of the solvent and the high mechanical strength of the fiber and film.

Cellulose has very high affinity with other materials, but due to the crystal structure made by strong hydrogen bonds in molecular chains or chains, it is difficult to dissolve in general solvents and NMMO is widely used among solvents that can break down the structure and prepare solutions. The method for producing and fiberizing a cellulose solution using the same has begun to propose an efficient and economical fiber manufacturing method, starting with US Patent No. 3,447,935.

In U.S. Pat. I suggested how to make it. This may take a long time from dissolution to spinning, resulting in a decrease in physical properties due to pyrolysis. In addition, there is a large amount of energy used, which is a factor of cost increase in economic terms.

International Patent WO 94/06530 proposes a method of concentrating a cellulose solution by removing moisture using a thin film distillation apparatus, but this method has disadvantages such as a reduction in production efficiency for preparing a high viscosity cellulose solution.

U. S. Patent No. 4,221, 574 proposed a method of swelling a cellulose sheet at 65 to 95 DEG C as a solvent with a liquid tertiary amine oxide containing 5 to 15% by weight of water and immediately stirring and heating it.

U.S. Patent No. 4,416,698 proposed a method of spinning by stirring a solid NMMO and cellulose pulp rather than a liquid phase, and WO 1997/47790 discloses a fibrillated cellulose powder having a water content of 5 to 5 instead of a cellulose pulp sheet. A method of mixing and spinning a high concentration NMMO aqueous solution maintained at 50 to 130 ° C. at 20% by weight in twinscrew was used. Since these methods cannot obtain a completely dissolved solution, there are disadvantages such as a cost increase by increasing the number of replacement of the filter to remove undissolved impurities and impurities before spinning.

U. S. Patent No. 5,584, 919 proposes a method for producing pellet-like cellulose mixed powder dispersed into the powder by uniformly dispersing tertiary amine oxide in cellulose powder, which has disadvantages such as low productivity and complicated process.

The present invention is to solve the problems as described above in the production of cellulose solution using a liquid NMMO concentrated liquid solution, unlike the conventional process by using the concentrated NMMO concentrated vacuum distillation of the concentrated NMMO from kneader process to extrusion process The purpose is to produce a highly homogeneous cellulose solution by making the swollen cellulose paste in the kneader by changing only the temperature conditions without removing the water by dissolving it in the extruder and dissolving it in the extruder.

1 is a process schematic diagram showing a homogeneous cellulose solution manufacturing process of the present invention

In order to produce a homogeneous cellulose solution in which undissolved cellulose particles do not exist, a step of uniformly mixing the cellulose powder with the liquid NMMO before the dissolving process and injecting and swelling the liquid NMMO into the cellulose powder is essential.

Method for producing a highly homogeneous cellulose solution according to the present invention for achieving the above object is to simultaneously inject the powdered cellulose and the concentrated liquid NMMO into the kneader maintained at lower than the extruder temperature and mixed by mixing, dispersing, shearing, pressing It is to prepare a homogeneous cellulose solution by pasting, pulling and superimposing the paste to swell the pulp and continuously injecting it into an extruder to dissolve it.

Therefore, the present invention,

(a) preparing a concentrated NMMO solution

(b) powdering the cellulose sheet

(C) injecting (a) and (b) into the kneader, respectively

(d) preparing a cellulose paste by mixing and swelling the injected NMMO solution with cellulose powder

(e) injecting the paste prepared in (d) into an extruder to dissolve to provide a method for producing a highly homogeneous cellulose solution.

More specifically, the high homogeneous cellulose solution according to the present invention,

(a) concentrating 50% by weight of NMMO hydrate to 87% by weight liquid NMMO (monohydrate) by distillation under reduced pressure

(b) powdering the cellulose sheet to 500 μm or less using a grinder;

(c) injecting the liquid NMMO and cellulose powder prepared in (a) and (b) into a kneader at 75 to 80 ° C.

(d) swelling the injected liquid NMMO and cellulose powder to prepare a paste of 10-15% by weight of cellulose powder;

(e) The cellulose paste prepared in (d) may be injected into an extruder and dissolved at 85 to 105 ° C.

U.S. Patent No. 4,416,698 and International Publication No. WO 1997/47790 disclose a method for producing a cellulose solution by mixing, swelling (pasting) and dissolving in an extruder, but the present invention provides a method for preparing a high homogeneous cellulose solution separately in an extruder. Since it is prepared by dissolving only by heating without swelling process, it is completely different from the existing patent in the method and principle of solution preparation.

Comparing the extruder structure to that presented in US Pat. No. 4,416,698 and International Publication WO 1997/47790, the patent describes that the extruder has more than nine blocks formed by complex sections of injection, swelling, and discharging. Since there is no swelling block, the structure of the extruder is simple and the manufacturing cost can be reduced, and the cellulose undissolved portion of the prepared solution is very small, so that the filter replacement cycle of the solution can be reduced, thereby reducing the manufacturing cost.

Hereinafter, a method for preparing a highly homogeneous cellulose solution according to the present invention will be described in more detail with reference to the accompanying drawings.

Figure 1 schematically illustrates a process for producing a highly homogeneous cellulose solution of the present invention.

In Figure 1, the cellulose powder can be obtained with a powder of less than 500㎛ using a grinder with a knife, preferably 300㎛ or less. When it is 500 micrometers or more, it does not disperse | distribute and swell uniformly in a kneader.

The 50 wt% NMMO aqueous solution is concentrated by distillation under reduced pressure to lower the water content to 10 to 20 wt%, which is used to swell the cellulose powder in the kneader and maintain the NMMO temperature at 80 to 90 ° C. during transport to the kneader. . The prepared cellulose powder and the concentrated NMMO solution were injected into a kneader maintained at 75 to 80 ° C., and the ratio of cellulose to NMMO was 5-20 wt%, preferably 9-14 wt%, depending on the degree of polymerization of the cellulose polymer. To be. The injected cellulose powder and the liquid NMMO produce uniformly dispersed cellulose paste through compression, tension, overlap, and shear in a kneader, and maintain the temperature at 75 to 80 ° C. while transferring it to the extruder. The cellulose paste forcedly transferred to the extruder at a predetermined speed is dissolved at 85 to 105 ° C., filtered, and then spun onto cellulose fibers and films.

Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited by the following examples.

The solution prepared in Example was evaluated in the following manner.

(a) Homogeneity of cellulose solution

Evaluation of the solubility of the cellulose powder prepared in the present invention was added to each of the cellulose powder treated according to the present invention in a reactor at 12% by weight relative to monohydrate NMMO (monohydrate NMMO) in the extruder and dissolved at 100 ℃ for 25 minutes Particles not evaluated were evaluated with a polarizing microscope.

(b) weight average degree of polymerization (DP _w )

The intrinsic viscosity [IV] of the dissolved cellulose was measured in a concentration range of 0.1-0.6 g / dl at 25 ± 0.01 ° C with a 0.5M cupriethylenediamine hydroxide solution made according to ASTM D539-51T using a Uberod viscometer. . The intrinsic viscosity was obtained by extrapolating the specific viscosity according to the concentration and substituting it into the equation of Mark-Houwink to obtain the polymerization degree.

[IV] = 0.98 × 10 ^-2 DP _w ^0.9

<Example>

A cellulose sheet having a weight average polymerization degree of 700 was placed in a grinder equipped with a 100 mesh filter to prepare a cellulose powder having a diameter of 500 μm or less, and the liquid NMMO (monohydrate) of 100 ° C., concentrated by a conventional method, was brought to 78 ° C. inside. The maintained kneader is injected at a speed of 7120 g / hour with a gear pump and the cellulose powder is injected at 880 g / hour with a screw feeder so that the final concentration of the prepared cellulose paste is 11% by weight. The retention time in the kneader was 8 to 10 minutes to prepare a cellulose paste, which was fed to the twin screw extruder laterally. The supplied cellulose paste was discharged after dissolving while maintaining each block temperature of the extruder at 90 to 95 ° C.

The concentration of the solution was 11% by weight, a homogeneous state containing little undissolved cellulose particles and the degree of cellulose polymerization in the discharged solution was 640.

Comparative Example

Cellulose powder having a diameter of 500 μm or less and liquid NMMO (monohydrate) at 100 ° C. were directly injected into a twin screw extruder, each block temperature was maintained at 90 to 95 ° C., dissolved, and discharged. The concentration of the solution was 11% by weight. When the solution was observed under a polarizing microscope, an undissolved powder having a diameter of 50 to 100 µm was present, and the degree of cellulose polymerization was 640.

The present invention powders the cellulose and injects it into the kneader simultaneously with the liquid-concentrated NMMO, and the swelled cellulose paste in the kneader is fed to an extruder of a somewhat higher temperature than the kneader, and then dissolved at a constant temperature, and then through a spinning nozzle. By manufacturing a highly homogeneous cellulose solution by extruding, it is possible to prepare a homogeneous cellulose solution in the dissolving process without decompression distillation and in the extruder without a separate swelling process. can do. Since there is no swelling block in the extruder structure, the extruder structure is simple and thus the manufacturing cost can be reduced, and the cellulose undissolved portion of the prepared solution is very small, so that the filter replacement cycle of the solution can be reduced, thereby reducing the manufacturing cost.

Claims (4)

Cellulose powder characterized in that the cellulose powder having a diameter of 500㎛ or less and the liquid concentrated NMMO at the same time injecting into the kneader, and then swelling the cellulose without kneading in the kneader to make a paste and then supply it to the extruder to dissolve in a homogeneous state Method of preparation of the solution. delete The method of claim 1, The temperature of the NMMO injected into the kneader is 80 to 90 ° C., the temperature of the kneader is 75 to 80 ° C., the temperature of the cellulose paste swelled in the kneader is maintained at 70 to 80 ° C. and transferred to the extruder. A method for producing a cellulose solution, which is dissolved in an extruder at 105 ° C. delete