JPS6031331B2 - Method of dissolving cellulose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dissolving cellulose.

Investment costs and environmental concerns are increasingly requiring other manufacturing methods to replace the viscose process for rayon production.

Numerous alternative production methods have been considered and published in the literature, but there is still no clear universal method that would allow the production of rayon in large enough quantities to replace the viscose process. It has not been done. The main object of the present invention is to use for the production of reconstituted cellulose products.
An object of the present invention is to provide a cellulose solvent system.

An additional object of the present invention is to provide a cellulose solvent system from which cellulose can be dissolved and from which high quality cellulosic products can be produced pharmaceutically in large quantities.

It is a further object of the present invention to provide a cellulose solvent system that allows the cellulose components to be easily regenerated and recycled with minimal impact on the surrounding environment.

The foregoing objects and other objects of the present invention are achieved by the following. That is, first, activated cellulose is treated with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone, and mixtures thereof, at a temperature that does not significantly cause decomposition.
Lithium chloride is mixed in an amount of 3 to 15% by weight based on the weight of the cellulose solution, and the cellulose is dissolved in the mixture of amide and lithium chloride. This dissolution step is particularly useful for producing reconstituted cellulose products. This method has the feature that cellulose can be dissolved without the formation of derivatives, which occurs, for example, in the viscose process. Therefore, the product regenerated from solution is in reconstituted rather than regenerated form. As a result, there is almost no depolymerization of cellulose from its initial, unaltered state to the molded product, and the degree of polymerization undergoes only a very small change. In addition to being useful in molded products such as fibers, films, or tubular containers, foams, etc., cellulose solutions are also useful as listed below. i.e. as adhesives, bonding agents for nonwovens, coatings, gluing agents for textiles, saturants for reinforcing textiles (cloths) and other matrices, as well as mediating further reactions to the cellulose backbone. It is effective as a medium and also stands in the study of the physical properties of cellulose.
Molded cellulosic products can be manufactured from solutions according to the invention using a variety of techniques.

Cellulose can be reconstituted into the desired form by contacting the cellulose solution with something that is not a solvent. The fibers are processed by wet spinning, dry jet-to-wet spinning, or dry spinning. Wet spinning technology involves spinning the cellulose solution directly into water,
It includes spinning techniques that expel into coagulants such as low alcohols with mono-acid groups, pyri-diso, acetonitrile, tetrahydrofuran, or mixtures thereof. Dry jet-to-wet pinning technology involves a spinisog technique in which the fibers are spewed into the air to align the cellulose molecules prior to coagulation, and then the fibers are passed through a non-solvating coagulating solution. ing. In the dry spinning technique, the cellulose solution is
The solvent is evaporated by a vigorous blast of heated air expelled into the air. The fibers are then passed through a paper thread or the lithium chloride is washed off.
Both dry-wet spinning and dry spinning are typically carried out using high solids cellulose solutions, ie, about 10% or more cellulose by weight. It is known that lithium chloride and dimethylacetamide are used to dissolve nylon polymers. L. Macromole by Wwolek
Cyama es, Vol. 10, No. 6, p. 1390, 1977 and T. 1. (See Bajr et al., p. 1396).
In addition, it is also shown in US Pat. No. 4,062,921 that a mixture of lithium chloride and dimethylacetamide with either 1-methyl-2-pyrrolidinone dissolves chitin.

Chitin is a substance that is a component of the hard shells of insects and crustaceans, and is an acetylated form of D-glucoseamine, which has amide bonds like nylon. Similarity to chitinous nylon is
This explains why they have similar solubility in the melting method. However, the chemical reactions and solubility of chitin are quite different from those of cellulose, and so far no dissolution method using cellulose has been used or even suggested. On top of that,
As will become apparent from the following description, the present invention involves more than simply dissolving cellulose in a solvent system. An important aspect of the present invention includes the use of activated cellulose to swell the cellulose and raise the pongee pores.

The pores of cellulose fibers have the property of closing naturally when they are wetted by an ionized solution such as water and then dried; once the pores are closed, hydrogen bonds continue to close the pores. It has a nature. Cellulose fibrils have potentially very large surface areas. However, these must be left unhindered so that they can be utilized for lithium chloride. Dimethylacetamide or 1-methyl-
The 2-pyrrolidinone solvents alone cannot be said to be sufficiently effective wetting agents to open the cellulose pores when they are not heated. Therefore, cellulose is activated by additional means in dissolving it in the dissolution method according to the invention. Cellulose dissolves when a mixture of lithium chloride and dimethylacetamide with either 1-methyl-2-pyrrolidinone is heated to a temperature of approximately 15,000 degrees Celsius or more. However, at these temperatures, the solution changes color and its inherent viscosity decreases significantly (e.g., from about 3.0 to 1.8 or less), causing the polymer chain structure to change. It is clear that this causes shortening of the body. As a result, a cellulose product of satisfactory quality cannot be produced from the solution and is therefore unsatisfactory. Thus, dissolution must occur at a temperature below that which causes significant degradation of the cellulose. Activation of the cellulose according to the invention is carried out at ambient temperature or at least 100 ml, where significant depolymerization is avoided.
This is accomplished by infiltrating the cellulose with a polar medium that causes the cellulose to swell and create pores so that the solvent can act on it at temperatures below 50 qo. It has been found that the dimethylacetamide or 1-methyl-2-pyrrolidinone used for activation must be substantially absent during the dissolution period for dissolution to be complete. There are many ionic substances that have the effect of wetting and swelling cellulose, and these contain activated hydrogen and act as cellulose precipitants or regenerants. The organic medium also wets the cellulose and counteracts the action of the amide-lithium chloride solvent system. If such an ionic solvent is used to activate cellulose, this solvent should therefore be removed for the final concentration, and this concentration is lower than that of cellulose and is generally Lower than 5%. These two seemingly prerequisite requirements, that a polar medium must be used for the activation of cellulose, but at the same time must be substantially absent for the dissolution of the cellulose, This led to the discovery of numerous methods to take. All of these methods discovered include the step of infiltrating the cellulose with a polar medium. If the polar homogeneous medium is not one of the amide solutions, the solvent is removed by a less polar medium than water or by replacing dimethylacetamide with 1-methyl-2-pyrodinone. Once replaced with a less polar solvent, this is then dried prior to dissolution. When drying, the pongee pores of cellulose become less likely to collapse because the cellulose impregnated with the silica solvent is dried. Examples of less ionic media than water that do not swell the cellulose and are useful in this invention include acetone, methanol, ethanol, isopro/f-nol, acetonitrile, and tetrahydrofuran. If it is replaced with midimethylacetamide or 1-methyl-2-pyrrolidinone,
Cellulose dissolves simply by adding lithium chloride. A number of polar media acting as swelling agents for the cellulose are used to open the cellulose tissue sufficiently so that the amides and lithium chloride can degrade the cellulose under normal environmental conditions.

Water, steam, and liquid ammonia are typical polar solvents that can produce clear solutions. The pre-use of water on cellulose before it is expanded is well known, and in practice the use of water before activation and subsequent replacement of water with acetic acid is currently not used industrially in the production of cellulose triacetate. It is used. however,
It has never been thought of to carry out activation and displacement with water to achieve the solubility obtained with a dissolution process similar to that in the present invention. In the present invention, cellulose is soaked in water, squeezed to remove excess water, and then treated with dimethylacetamide or 1-methyl-2 to create an activated cellulose that is ready to dissolve.
- substituted with pyrrolidinone. Softening by exposure to steam for several minutes and subsequent substitution of dimethylacetamide with 1-methyl-2-pyrrolidinone can also produce activated cellulose which dissolves readily under normal environmental conditions. . Even when cellulose is soaked in ammonia solution and then evaporated, if the amide is added before the ammonia evaporates, a clear solution is produced that dissolves at room temperature. As previously mentioned, unactivated cellulose can be heated in a solution of amide and lithium chloride until the temperature of the solution reaches a point where significant annihilation or complete depolymerization occurs (usually about 150°C or higher). It will not melt directly unless it is heated.

However, it has been found that cellulose can be activated by using heated vapor of one of the solvent amides. Cellulose is mixed with dimethylacetamide or 1-methyl-2-pyrrolidinone and the mixed suspension is briefly boiled. After stopping the heating, the suspension is cooled to a temperature well below 150°C (e.g. about 100°C) before lithium chloride is added and the mixture is stirred several times until the cellulose is in complete solution. Time is worshiped. At or near the boiling point, the amide is allowed to penetrate through the capillaries of the fiber by steam with a sufficiently high pressure;
This causes the fiber to expand. L added to suspension
Regarding iCI, dissolution occurs due to interaction between LiCI and dimethylacetamide in or around the cellulose fibers. The resulting solution is colorless and transparent and has not been modified in any way. V. (intrinsic viscosity hereinafter abbreviated as 1.V.) is 3.0, which is not much lower than 2.7. V. Creates regenerated cellulose with 1. V. It is generally believed that the slightly lower value is due to slight degradation or depolymerization of the polymer.

It was recognized that amide and lithium chloride form an acidic complex, and the methods for activating and dissolving cellulose described so far are based on this discovery.

A simple litmus check shows that the dissolution of dimethylacetamide and lithium chloride in water is acidic, but surprisingly neither solution is acidic on its own. The above results indicate that the decomposition of the polymers that occur when cellulose, dimethylacetamide, and lithium chloride are heated occurs as a result of the acidity of the aforementioned amide and lithium chloride complexes. By impregnating the cellulose with only a heated solution without lithium chloride, the cellulose is activated with amides without damaging the polymer. Lithium chloride is then added at a temperature such that the presence of the acid-producing complex does not interfere with polymerization. Yet another method of activating cellulose to dissolve is by mechanically opening the cellulose tissue to facilitate penetration of the cellulose by one of the polar media. This is accomplished by passing the cellulose suspension through a homogenizer under high pressure. In such processes, energy is imparted to a low viscosity cellulosic suspension by flowing it at high velocity through a confined area. By repeatedly passing a cellulose suspension through such a homogenizer, a microfibrillar structure of cellulose can be created without significantly affecting the degree of polymerization. The liquid in which the cellulose is suspended for passage through the homogenizer may be water, dimethylsulfonate oxide, aqueous ammonia, dimethylacetamide or other polar solutions. Cellulose with a microfiber structure does not need to be heated,
Cell again. - There is no need to use other aionic solutions for activation of the gas, and it is dissolved in dimethylacetamide or a mixture of 1-methyl-2-pyrrolidinone and lithium chloride. If the polar liquid used to treat the microfibrous slurry is not dimethylacetamide or 1-methyl-2-pyrrolidinone, water such as acetone, tetrahydrofuran, or isopropanol, which does not wet the cellulose, Less polar liquids or dimethylacetamide or 1-
It should be replaced with methyl-2-pyrrolidinone. If replaced with a non-polar liquid, it must be dried before dissolution. If dimethylacetamide is exchanged for 1-methyl-2-pyrrolidinone, it is dissolved by adding lithium chloride. All of the methods for activating cellulose that have been described so far involve separate treatment of the cellulose, thus increasing the final production cost.

Naturally, it would be preferable to eliminate such a separate treatment, but it has been found that cellulose can be activated even without a separate treatment by using its melting step in combination with a regeneration and recycling step. The cellulose-lithium chloride-amide stock solution must finally be washed with water to remove the lithium chloride and dimethylacetamide, so in the mass production process, the lithium chloride/amide/water solution is used for regeneration and IJ cycles. Produce a solution of

so that it can be used to dissolve activated cellulose.
Rather than attempting to purify the lithium chloride amide by removing the water, the lithium chloride/amide/
It has been found that an excellent cellulose solution can be obtained by adding standard cellulose to an aqueous cellulose regeneration solution and then decomposing the excess water. This fractional distillation of water must be carried out until the remaining amount of water is at most approximately 5%, preferably less than 4%, of the total weight of the solution. Otherwise, dissolution of cellulose will not occur. There were some fibers that did not dissolve into the solution above about 5% water. The presence of more than 5% water appears to hydrate the lithium chloride and impair its affinity with cellulose.

(5% from the percentage of water relative to the total weight of lithium chloride, of course, now occurs). The melt-recycle-recycle sequence, which combines a cellulose melting step with a regeneration and recycling step, is more economical than any other method for activating and dissolving cellulose. Cellulose solutions are made using this method with up to 16% cellulose by total weight. High-quality textiles and films can then be spun from this cellulose solution. The invention has a specific meaning for lithium chloride on the one hand, and also for dimethylacetamide and 1-methyl-2-pyrrolidinone on the other hand.

Experiments were conducted using solutions of a number of halogenated salts at various concentrations, temperatures, and pressures as listed below. The solution is dimethylacetamide, 1-methyl-2-pyrrolidinone, dimethylformamide, formamide, trifluoroacetamide, tetramethylurea, dimethylsulfoxide, piverizine, pyridine, sulfur, fluorene, ethylfluoromate, etc. The temperature ranges up to 21,000 degrees Celsius, and the pressure ranges from atmospheric pressure to 572 kilopascals. Among these tests, the only ones that were able to melt cellulose were lithium chloride and 1 - Either methyl-2-pyrrolidinone or dimethylacetamide. All other salts and compounds in solution did not dissolve cellulose, regardless of temperature or pressure. Lithium chloride It should be present in the solution in an amount within the range of 3-15% of the total amount.

If lithium chloride is less than 3% of the total amount of the solution, it tends to be insufficient for dissolving cellulose, and if it is more than 15%, the amide becomes supersaturated and the dissolved cellulose becomes a salt and separates from the solution. It tends to be. The preferred concentration of lithium chloride is about 5-12% by weight. In the method of the invention it was possible to obtain a solution with a concentration of 16% by weight of cellulose based on the total weight of the solution. Typically, the remaining components of the solution are dimethylacetamide or 1-methyl-2-pyrrolidinone. There are many types of cellulosic raw materials that can be used to process the cellulose solution in this invention, such as chemical pulp, sulfites, pre-hydrolyzed, bleached or unbleached kraft paper. Short fiber fluff, regenerated cellulose, and refined knot fibers remaining on the seeds after long fibers are explored in a cotton dryer are also typical cellulose raw materials. Unrefined cellulose (e.g.
Sawdust) is also available, but it is far less efficient than purified cellulose. The examples listed below are examples of the invention.

All parts and percentages are by weight unless otherwise indicated. Example 1 An example of activation of cellulose by the use of heated steam of one of the solvent amides will now be described.

Pre-hydrolyzed kraft pulp cut through a 0.125 inch screen was placed in a flask and dimethylacetamide was added thereto.

Heat the mixture at renuk temperature (16500) for 30 minutes with constant stirring. The suspension is then slowly cooled to 10,000 ℃, at which point anhydrous lithium chloride is added at a constant rate. The resulting mixture is then allowed to cool to room temperature and left stirring overnight. The weight ratio of cellulose/lithium chloride nodimethylacetamide, which is a component of the above-mentioned mixture, was 5.9/8.6/85.5 when expressed as a percentage. The next morning, the cellulose was completely dissolved and the mixture became a clear aqueous solution. Therefore, this solution was diluted with 60% dimethylacetamide, and then centrifuged for 1 hour, suctioned through a sieve, and filtered. The permeate is regenerated underwater and its inherent viscosity determined. This experiment was repeated using different solvents and different relative proportions of cellulose, solution, and salt for each of a series of different grades of pulp. We also conducted an experiment using rice grains instead of cellulose. However, in each case the salt used was lithium chloride. The results of these experiments are shown in Table 1. Cuenel in the table. V.
is the intrinsic viscosity of regenerated cellulose calculated based on a concentrate of 1 mole of Kippur ethylene diamine. Table 1 * Weight % Cellulose/LiC and/Solvent Table 1
This shows that among the solvents tested, only de/methylacetamide and 1-methyl-2-pyrrolidinone were effective in dissolving cellulose in the presence of LjCI.

Even materials with a very high degree of polymerization (D.P.) have a relatively small D.P. It was possible to dissolve it due to P loss. Experimental Example 2 Here, an example will be described in which cellulose is activated using water and then the solvent is replaced to dissolve the cellulose.

280% pre-hydrolyzed kraft pulp (Cue
nel. V. = 3.00) into 5 x 5 inch sheets, soaked in water for 10 minutes at room temperature, then placed the kraft pulp sheets between 6 x 6 inch stainless steel mesh screens. 2.000 psig (×6.8
9=13.780 kpa) was applied.

The pulp sheet was then immersed in 800' dimethylacetamide for 30 minutes at room temperature and a pressure of 2,000 ps g was applied again as above. A sample of the activated pulp was analyzed to determine how much water it contained and found to be 8.5% of the total amount. The pulp sheet is then cut into pieces and mixed with 400 grams of anhydrous lithium chloride in a total of 4000 grams of dimethylacetamide for 3 hours at room temperature. When it was left as it was overnight, it was able to dissolve. This solution contained 0.51% of the total amount of water. Using this water and using activation techniques, it was possible to create a cellulose concentrate reaching a concentration of 6.5%. Thus Cuenel. V. (Intrinsic viscosity)2
．． 83 regenerated cellulose could be obtained. Experimental example
3 Here, we further changed the combination of salt/polar solution using the method described in Example 2 to create various combinations other than those discussed in Example 2, and conducted experiments for each.

To give an example of a combination, first, use lithium chloride as the salt,
A method of combining with 1-methyl-2-pyrrolidinone, dimethyl formamide, dimethyl sulfoxide, formamide, or ethanolamine, and
We tried a method using calcium chloride or magnesium chloride as a salt to be combined with dimethylacetamide. Regardless of the combinations mentioned above, in all cases the cellulose was activated by immersion in water, this water was replaced with the solvent mentioned above, and cellulose dissolution was attempted by the salt/solvent combination. The results of this experiment are shown in Table 0. Table 1-DMAC: Dimethylacetamide 3
-DMSO: dimethyl sulfoxide 2-MP:
1-Methyl-2-pyrrolidinone 4-DMF: Dimethylformamide From the table below, only when lithium chloride is used as the salt and dimethylacetamide or 1-methyl-2-pyrrolidinone is used as the solvent, cellulose can be dissolved as described in Experimental Example 2. The solution was dissolved using a water activation and solution exchange technique.

Experimental Example 4 Here, as an example of activating cellulose using steam and subsequently dissolving the cellulose by exchanging the solvent, such a method is used to obtain a mixture of cellulose/LiCI/dimethylacetamide and a percentage of their respective weight ratios. 6.
A solution of 0/8.5/85.5 was used to treat 2.5.

140 ml of pre-hydrolyzed kraft oil sheets were cut into 5 x 5 inch sheets and exposed to steam for 2 minutes each, then soaked in 700 ml of dimethylacetamide and subjected to solvent displacement. In order to complete this, we performed rope worship at a constant speed for an hour.

After applying a pressure of 15,000 psig, the water content of the displaced pulp sheet was analyzed to be 5.
It was 24%.

As described in Example 2, the sheet was cut into pieces and then mixed with a solution of 200 ml of LjCI in 2,000 ml of dimethylacetamide. At room temperature, melting of the pulp took place in less than 4 hours, and the water content of the solution thus formed was 0.29% of the total volume.
Instead of pre-activating the pulp using water or steam in Experimental Examples 2 to 4, 5.10% of each
, and 20% cedar.

If lithium chloride was added too late, it was not possible to obtain a cellulose solution at room temperature. This indicates that it is not just the presence of water that is important, especially if the sample is not heated, but the order of exposure to water that is important for cellulose dissolution. Experimental example
5 Here, an example of activating cellulose using liquid ammonia will be described.

1 piece of pre-hydrolyzed kraft pulp cut to pass through a 0.125 inch screen;
Measured in a glass trap immersed in a dry ice-acetone solution.

Gaseous N ratio was passed through this trap and in 10 minutes a liquid N ratio of about 35 was concentrated in the trap. Next, the pulp is soaked in this N ratio for 15 minutes, after which the N
& was slowly evaporated over 2 minutes. This evaporation effect was carried out using a heated pot. Forty minutes of dimethylacetamide was added before all of the N was evaporated, and the last traces of NH3 were removed by bubbling N2 vapor into the mixture. The pulp was then treated in dimethylacetamide with 10% lithium chloride and left overnight at room temperature. The weight ratio of the constituents cellulose/lithium chloride/dimethylacetamide of the initial mixture was 2.2/8.9/88.9 in percentages. In this way, a transparent cellulose solution could be obtained. Gaseous ammonia alone was not enough to bring about the outcome of the aircraft. Experimental Example 6 This example and the three experimental examples that follow all relate to a method of mechanically opening cellulose tissue in order to aid in the penetration of acetic solvents into cellulose and promote its activation. It is.

A slurry of pre-hydrolyzed kraft pulp containing 2% dimethyl sulfoxide
Microfibrous tissue was obtained by passing through a homogenizer at 0 and 8000 psig pressure. The cellulose with a microfiber structure was suctioned through a sieve filter, washed with Ascent, then dried in an oven at 60 qo for 2 hours, and then in a dimethylacetamide solution containing 5% lithium chloride. It was incubated overnight at room temperature. As a result, a transparent solution was formed in which the component weight ratios of cellulose/lithium chloride/dimethylacetamide were 2.3/4.7/93.0, respectively. Microscopic photography revealed the presence of some fibrils. cell. The base can be in the form of fibers, tubular films, or flakes; various non-solvents,
For example, it can be regenerated from acetone or acetonitrile.As is clear from the fact that Cuenel. Example 7 Here, a 2% slurry of water containing the cellulose pulp according to Experimental Example 6 was heated in advance at 7500, then passed through a homogenizer at 10000, applying a pressure of 8.000 pSjg. did.

Then, the slurry was filtered by suction using a filtration device, and the pulp was replaced with dimethylacetamide over 4 hours at room temperature, after which the slurry was filtered by suction using a filtration device. The resulting pulp was treated at room temperature with a dimethylacetamide solution containing 10% lithium chloride, with a component weight ratio of cellulose/lithium chloride/dimethylacetamide in percentages of 2.2/8.9/88. A clear, colorless solution was formed. Experimental Example 8 Another method of using cellulose with a microfibrous structure to promote cellulose activation and dissolution is to simultaneously mix the three components of cellulose, lithium chloride, and dimethylacetamide in a homogenizer. be.

By adding increasing amounts of cellulose pulp according to Example 6 to the dimethylacetamide circulating in the homogenizer until a 4% slurry is formed with respect to the total pulp with microfibrous structure. A microfibrous tissue was obtained. Successive batches of anhydrous lithium chloride were added at levels of 2.5%, 5%, 7.5%, and 10%.

The temperature of the circulating slurry is kept below 110 oo.
It was dropped into a homogenizer at a pressure of 6.00 sig. Samples of the mixture were collected after all lithium chloride additions at each level were completed, and this was then stirred overnight at room temperature. From micrographs, at least 5%
It was found that in mixtures containing lithium chloride, lithium chloride was only partially dissolved without caramelization. However, when a batch containing 10% lithium chloride was heated at 160 qo for an additional 18 minutes and then cooled to room temperature, it dissolved but was accompanied by caramelization, indicating significant polymerization failure. EXPERIMENTAL EXAMPLE 9 A 3% slurry of pre-hydrolyzed kraft pulp in dimethylacetamide was microfibrillated by applying a pressure of 3.000 psig in a homogenizer at a maximum temperature of 1250. .

Lithium chloride was then added externally to each of the two batches of homogenized slurry, each under different conditions. The weight ratio of cellulose/lithium chloride/dimethylacetamide in the first batch was 3/8/
It was 89 (%). When this was heated at 165 oo for 30 minutes, cooled to room temperature, and stirred overnight, it dissolved but caramelized. Cuenel. of cellulose thus regenerated. V. was also 1.77, compared to 3.0 for the unaltered original. The second batch (this ingredient ratio is 2.2/7.8/90.0) was heated to 8000C;
It was also cooled to room temperature.

As a result, dissolution occurred within 2 hours. and regenerated cellulose Cuenel. V. was 2.54. Experimental Example 10 This is an example of the melting of cellulose in a regeneration solution consisting of lithium chloride/amide/water.

This regenerant solution contains 20% LiC, 200% dimethylacetamide, 500% dimethylacetamide, and is kept at atmospheric pressure until the distillation pot temperature reaches 110% until the 450% water is removed. °C, average temperature 100oo
It was partially distilled. Once 450 m of water had been removed, 10 m of cellulose pulp was added and distillation continued until all remaining water had been removed.

This means that the temperature of the pot is 12,000℃ and the pressure is 20℃.
It was carried out at m. Although the water content of the suspension remaining in the pot is less than 1% of the total amount of liquid, cellulose
The fibers were still completely intact and could be dispersed without difficulty. It is industrially advantageous to be able to use pumps to move the slurry. This is because if the pump is not available, the slurry will be transferred to its own storage tank. The dispersion is allowed to remain undispersed without stirring to cool the slurry. Also, after being allowed to cool for at least 6 hours, a very sticky clear cellulose appeared in the lithium chloride/dimethylacetamide in the flask. Experimental Example 11 Here, a solution of cellulose in lithium chloride and dimethylacetamide was prepared as described in Experimental Example 10.

The viscosity of this solution was measured using a Brookfield viscometer and was found to be 40.00 specific ps at 2500 ps. The solution was filtered through a pancake-shaped polypropylene filter and discharged into a multi-type primary paper yarn chamber maintained at 2500 ℃ in a bench scale vertical spinning apparatus. The components of the liquid in the primary spinning bath are as follows: water, methanol, isopropanol, pyridine, acetonitrile, tetrahydrofuran, and the aforementioned mixture containing corresponding amounts of lithium chloride and dimethylacetamide.

The fibers formed by the primary edge filament are guided through the second air filament to the next godet.

In the spinning machine, a glass spinning hole with 30 holes of 63.5 microns each on the surface was used. All samples were chemically processed as staple fibers in 7,000 ml of water.
Centrifuge and dry in oven at 100 oo overnight.

Cuenel. of exhaled fibers and refined wood pulp reconstituted from the original cellulose solution. V
．． When measured, the intrinsic tackiness of the final reconstituted cellulose was 2.95, compared to 3.0 for the original solution. In addition to the above-mentioned fibers, by changing the design of the glass spinning tip, you can easily create the desired shape: for example, a high-quality film, a membrane with a natural pure tubular structure. cellulose, and even cellulose films for packaging materials. Experimental Example 12 Here, a method is described in which undried grated pine sawdust is used instead of refined wood pulp.

20 mesh of undried sawdust (containing 47% water) was soaked mechanically in 200 °C of water for 1 minute, left overnight, and then I sucked it up with a device.

The regeneration solution, containing 20 g of lithium chloride, 20 g of dimethylacetamide, and a total of 10 g of water, was partially distilled as described in Example 10. Analysis of the dissolved material in LiCI/DMAC revealed that the theoretical cellulose content of sawdust (approximately 40%)
13.5% of the amount was dissolved. EXPERIMENTAL EXAMPLE 13 Here, 300 grams of pre-hydrolyzed kraft pulp, cut to a size that would pass through a 0.125 inch screen, was suspended in water.

After soaking for 3 minutes, the suspension was evacuated using a house vacuum through a hole in a large piece of coarsely crushed glass.

The wet refined wood pulp is further pressed using a rubber dam to remove excess adhering water. Dimethylacetamide was then added to the filter funnel and the water activated refined wood pulp was suspended. A vacuum was applied to remove excess liquid and the solids were squeezed out again through a rubber dam. The treatment with dimethylacetamide is repeated again and the activated, substituted cellulose pulp, after being squeezed by a final rubber dam, is cooled overnight and subjected to solution preparation as described below. agent). 1.380 cc (1.286 m) of dimethylacetamide was placed in a 1 gallon capacity, two-blade mixer.

After applying the heating brine jacket, the mixer was started and then 235 m of lithium chloride was introduced. Lithium chloride LiCI and dimethylacetamide DMAC were added at 61% to ensure a good solution of LiCI.
Mixed for 1 hour at °C. The previously activated pulp was added to the LiCI/DMAC mixture solution over a period of 4 minutes. The heated brine was turned off and the whole mixture
and mixed for minutes. Cold brine was then circulated in a cooling jacket to prevent overheating and incubated at 0° C. for an additional 4 hours. The thoroughly mixed and fully expanded slurry was placed in a refrigerator for two days at 5° C., so that the cellulose was completely dissolved as evidenced by microscopic examination. Solution is 15% cellulose
, 12% lithium chloride LiCI, and 73% dimethylacetamide DMAC. Experimental example
14 Here, a solution containing 6% cellulose in one LiCI/DMAC is added to the cellulose/
In order to make the weight ratio of LiCI/DMAC 6//8/86, it was activated with water as described in Experimental Example 2,
Processed using pulp substituted with DMAC.

The inherent viscosity of the resulting solution is 54.00 ps at 2500.
Through the glass paper pile protrusion opening with 300 holes with a size of 63.5 microns per hole on the surface, 31p of acetonitrile is passed into the acetonitrile case that performs the coagulation action.
・I was spit out by s.i. The conditions during spinning were as follows. Jet extension = 1.655, Godet extension = 78
．． 5%, 1st coagulation = 2300 using acetonitrile, 2nd spinning rate = 2300 using air The fibers were washed with 6500 ml of water, wrung dry, and the finished standard season fiber (trade name NopcoRSF15), centrifuged to remove excess finish, and dried in an oven at 100°C overnight.

The inherent tackiness of this fiber is Cuene l. V. is 2.68 compared to 3.0 of the original pulp (starting material).
As a result of the overall treatment, the degree of polymerization (D.P.) was only slightly reduced. The amount of water held in this fiber accounted for 72% of the total water content, and it had the following physical properties. fiber thickness
1.23 denier conditional adhesive strength
3.74 t/d wet adhesion
2.649/d conditional extension 6
．． 20% tide elongation 8.70
% wetting coefficient: 1.40/d at 5% elongation From these results, it can be seen that a high quality fiber with a high wetting coefficient can be produced by using wet spinning technology.
It was revealed that it was created from I/DMAC.

Example 15 15% cellulose, 12% LiC1, and 73%
A cellulose semi-solid solution containing DMAC and having a high solids content such as that taken up in Experimental Example 13 has a viscosity of several million cps at 2500° C. and is essentially a transparent gel.

300 cc of this cellulose solution is placed in a high pressure extrusion device equipped with a glass spinneret having 36 holes of 200 microns each on the surface. The solution was heated to 110°C with an electric band heater surrounding the solution extrusion cylinder in the high-pressure extrusion device.
It is kept free of air in a vacuum house for at least 3 hours to remove any bubbles that were initially present. The extruder was moved to a fully upright vertical position and the fibers were extruded downward through gaps ranging in length from 0.5 inches to 3 feet at a rate of 10 grams per minute.

The draw rate is adjusted to provide a fiber of the desired final denier, and the air drawn fiber passes through a coagulation chamber. This bath may contain any of the coagulants described above, but in this example water was used. The fiber passes under the primary godet and is directed to a secondary godet where additional secondary stretching is performed sufficient to give a final fiber thickness of 2 denier. The fibers are then washed to remove residual LjCI and dimethylacetamide, wrung and subjected to standard rayon final processing, centrifuged and dried in a heated air oven. Fibers can be produced by this technique.

Dry jet wet yarns in high solids cellulose solutions have excellent wet/dry tack retention ratios, with wetting coefficients greater than 0.40 that increase with dry jet elongation to wet godet secondary elongation levels. . Experimental example 1
6 In this example, the high solids content cellulose solution described in Experimental Example 13 has a cellulose/LiCI/DMAC composition ratio of 1.
5/12/73, and was spun using a pilot plant spinning device normally used for spinning cellulose acetate liquid.

However, in this case the temperature of the heated air was changed to allow the dimethylacetamide to be removed without fiber destruction or cellulose force ramelization.
For this purpose, the air heating device and air flow were designed so that the extruded fibers did not reach a temperature above 140 oo. The fibers exiting the bottom of the apparatus at 300 rpm are directed into a counter-flowing heated water bath where they are further stretched, while the LiCI is washed away and directed to the regeneration and recycling tower. Fibers can be produced by this technique, and dry spinning of high solids cellulose solutions can provide an excellent balance of conditional/wet adhesion, conditional/wet elongation, and high wet modulus.

Claims (1)

[Scope of Claims] 1. Activated cellulose is treated with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone, and mixtures thereof, at a temperature that does not cause significant degradation. Dissolution of cellulose, characterized in that it is mixed with 3 to 15% lithium chloride by weight dissolved in the amide, and the cellulose is dissolved in the amide solution containing the lithium chloride without significant degradation. Method. 2 The amount of lithium chloride dissolved in the amide is 3 by weight.
12%, and the cellulose is dissolved in the amide and lithium chloride without significant deterioration in the absence of substantially any polar medium other than the amide. Method of dissolving cellulose. 3. The method for dissolving cellulose according to claim 2, wherein the activation of cellulose is by infiltration of a polar medium which has the property of swelling cellulose and is different from the amide which is removed before the cellulose is dissolved. 4. The method for dissolving cellulose according to claim 2, wherein the activation of cellulose is promoted by the microfiber structure of cellulose. 5. The method for dissolving cellulose according to claim 3, wherein the polar medium is a liquid that swells cellulose. 6. The method for dissolving cellulose according to claim 3, wherein the polar medium is replaced with a medium less polar than water before dissolving the cellulose. 7. The method for dissolving cellulose according to claim 5, wherein the polar medium is a liquid selected from the group consisting of water, ammonia, dimethylacetamide, and dimethylsulfoxide. 8. The method for dissolving cellulose according to claim 3, wherein the polar medium is dimethylacetamide vapor. 9. The method for dissolving cellulose according to claim 7, wherein the polar solution is water. 10. The method for dissolving cellulose according to claim 2, wherein the activated cellulose is cellulose pulp from which water has not been removed after pulp production. 11. The method of claim 10, wherein the water in the cellulose pulp is replaced with a liquid that does not swell the cellulose before dissolving it. 12. The method of dissolving cellulose according to claim 3, wherein the cellulose is a cellulose pulp that has been dried before activation. 13. The method for dissolving cellulose according to claim 2, wherein the cellulose is dissolved at a temperature of 150°C or lower. 14. The method for dissolving cellulose according to claim 2, wherein the cellulose is dissolved at room temperature. 15. The method for dissolving cellulose according to claim 2, wherein dimethylacetamide is used as the amide. 16 Before lithium chloride is added, cellulose is added to the amide and the mixture of cellulose and amide is heated to a temperature of at least 150 °C, then 10
The method for dissolving cellulose according to claim 2, wherein lithium chloride is added after cooling to below 0° C., and the mixture is stirred until dissolution is complete. 17 Cellulose is activated by infiltrating the cellulose with a polar medium that has the property of swelling the cellulose, and up to 16% by weight of the activated cellulose is produced at a temperature that does not cause significant degradation of the cellulose. 2. The method for dissolving cellulose according to claim 1, further comprising stirring in order to dissolve cellulose in the amide solution containing lithium chloride in addition to the amide solution containing lithium chloride. 18. The method for dissolving cellulose according to claim 17, wherein the cellulose is dissolved at a temperature of 150° C. or lower. 19. The method for dissolving cellulose according to claim 1, wherein the cellulose is dissolved in the presence of a polar medium other than an amide having an active hydrogen atom in an amount not exceeding 5% by weight. 20 An amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof, at a temperature such that no significant degradation occurs, and 3 to 15% by weight dissolved in this amide. Cellulose, which is characterized by adding cellulose to a solution containing lithium chloride and water, evaporating water from the solution until the water content in the solution becomes 5% or less by weight, and dissolving the cellulose in the solution. Method of dissolving cellulose to form a solution.