JP2672937B2 - Pre-doped granules of cellulose and tertiary amine oxide and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a pre-doped granule of cellulose and a tertiary amine oxide in which a tertiary amine oxide is homogeneously dispersed in a cellulose and permeates therein, and a method for producing the same. The invention also relates to a method of making a dope solution of cellulose for spinning into cellulosic articles such as fibers and membranes.

[0002]

The method of producing cellulosic fibers using tertiary amine oxides has significant advantages over conventional methods using viscose spinning solutions. This is because the tertiary amine oxide is a solvent that is less toxic than viscose. The method using a tertiary amine oxide can provide a clean environment for workers, and significantly reduce the amount of wastewater and possible environmental pollution in the process of producing fibers. Furthermore, the viscose method is very complicated and involves high energy consumption, but the tertiary amine oxide can be completely recovered. Therefore, the latter method is more economical than the former method in terms of manufacturing cost. Moreover, the fibers obtained by the latter method are superior to the fibers obtained from viscose rayon in terms of physical properties such as tensile strength. Therefore,
The latter fibers can be used as synthetic fibers with various advantages.

A process for making shaped cellulosic fibers from a solution of cellulose in a tertiary amine oxide solvent was first described by Graenacher et al. In US Pat. No. 2,179,181, issued 1939. Proposed. According to this proposed method, cellulose 7-1
0 wt% is dissolved in a tertiary amine oxide solvent.

Since then, numerous methods have been proposed for producing cellulosic fibers more effectively and economically. The majority of such methods have focused on producing solutions with high solids content, mainly eliminating the problem of low processability due to the high concentration of the solution. For example, a method using N-methylmorpholine-N-oxide solvent is proposed in US Pat. No. 3,447,939 to Johnson, which uses dimethylsulfoxide, N-methylpyrrolidone or sulfolane diluent in the solution. A method is proposed in US Pat. No. 3,508,941 to Johnson, and a method using amines as cosolvents is US Pat. No. 4,290,815 to Henry and US to Vargar. It is proposed in Japanese Patent No. 4,324,539.

A method for producing a solution containing a high concentration of cellulose solids in an amine oxide containing an appropriate amount of water is described in US Pat. No. 4,142,913 to McCorsley et al., US Patent to McCorsley. Fourth 4,144,080
No. 4,196,282 to Franks et al.
And U.S. Pat. No. 4,246,246 to McCorsley
No. 221 is disclosed. However, since the solutions according to the above patents are too viscous for wet spinning, these patents use air gap spinning technology to increase the production yield.

According to the methods disclosed in these patents,
Cellulose was added to a solution of a tertiary amine oxide containing 50% or more of water to form a slurry by swelling, and then excess water contained in the slurry was distilled off under reduced pressure.
A cellulose solution used for spinning is formed. The solution obtained is fed to an extruder equipped with a spinneret. However, these methods necessarily require a long time for distillation under reduced pressure. This causes pyrolysis of the cellulose and thus discoloration of the spinning solution with a decrease in the molecular weight. Moreover, the solution obtained has the drawback of causing some deterioration of the physical properties after spinning.

US Pat. No. 4,142, McCorsley et al.
913 and McCorsley U.S. Pat. No. 4,1.
44,080 discloses an azeotropic distillation method in which a non-solvent such as alcohol, dimethylformamide, dimethylsulfoxide, toluene or xylene is added to more easily remove excess water. However, these methods suffer from the additional complex step of separating the non-solvent material from the water, as large amounts of the non-solvent material contained in the removed water must be recovered for reuse. Have In addition, in the process of concentrating the cellulosic solution, the concentrating temperature must be raised as the concentration of cellulose increases to increase the concentrating time, and more energy is needed to stir the slurry, which may have higher viscosity. Becomes Therefore, it is difficult to carry out this by a continuous method, resulting in low productivity.

US Pat. No. 4,211, to McCorsley et al.
No. 574 is a method for producing a cellulose solution, in which a pulp sheet of cellulose is immersed in a liquid tertiary amine oxide at 89 to 95 ° C. having a water content of 5 to 15% to swell, A method is disclosed in which the mixture is stirred and heated without concentration. This method has an advantage that a cellulose solution having a high solid content can be produced in a short time without concentration. However, since the liquid phase of amine oxide can swell the cellulose at the same time as dissolving the cellulose, there is a possibility that a coating film may be formed on the surface of the undissolved pulp. This precludes deep penetration of the amine oxide into the pulp. Thus, this method has the drawback that even if the solution is vigorously stirred or heated, a homogeneous solution cannot be formed due to the presence of undissolved cellulose.

EP 356,419 to Stefan et al. Proposes a continuous process for producing large quantities of cellulose solution in a short time by the same concentration step as the above process. According to this method, a cellulose slurry having a weight average degree of polymerization (DP _w ) of 1,400, obtained by swelling cellulose dissolved in a tertiary amine oxide containing 40% by weight of water, is passed through a fan screw channel. Transfer to an extruder equipped with a screw that has,
In this extruder, it is distilled under reduced pressure with a residence time of 3 minutes to form a cellulose solution at a rate of 72 kg / h.
In this method, a fan screw is used to transfer the slurry simultaneously with its concentration. This method involves the problem of high manufacturing costs due to the energy used to drive the screw.

The various processes for preparing the tertiary amine oxide solution of cellulose proposed in the prior art patents as mentioned above can be divided into the following two categories.

Category I US Pat. Nos. 4,142,913 and 4,144,08
0, 4,196,282, 4,246,221
And 4,290,815 and European Patent No. 3
Method disclosed in 56,419

[0012]

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Category II The method disclosed in US Pat. No. 4,211,574.

[0014]

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[0015]

The cellulose solution obtained by the above method has a high viscosity and is in a phase in which cellulose is dissolved. It takes several hours to several days for the solution to solidify. Therefore, it is very difficult to convert the cellulose solution into chips. Moreover, even if the solution is converted to chips, cellulose decomposition and solution discoloration may occur during the further dissolution steps carried out in the extruder to spin the solution. Therefore, in order to avoid these drawbacks, the solution must be transferred in the liquid phase directly into the extruder without the chipping step. Otherwise, it will take a long time to manufacture the chip.

As mentioned above, the present inventor has extensively researched the above-mentioned conventional method for producing a cellulosic solution in order to provide a practical method capable of forming a cellulosic article. As a result, the present inventor
It has been found that the above problems can be overcome by grinding and kneading with a solid tertiary amine oxide powder having a specific water content. Grinding and kneading gave pre-doped granules in which the tertiary amine oxide was homogeneously dispersed in the cellulose and subsequently heating the pre-doped granules in the extruder barrel to dissolve the cellulose. The dope solution is extruded to obtain an extrudate for use in spinning and the extrudate is spun through a spinneret or die. The present invention has been completed based on this discovery.

[0017]

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide a method of making pre-doped granules of cellulose and tertiary amine oxide powder.

Another object of the present invention is to provide pre-doped granules produced by the above method.

Yet another object of the present invention is to provide a dope solution of cellulose for spinning the granules after they are transferred to the extruder without the chipping step.

Another object of the present invention is to provide a method for producing shaped cellulosic articles such as fibers and membranes from dope solutions of cellulose.

[0021]

These objects of the present invention can be achieved by a method of making pre-doped granules of cellulose and a tertiary amine oxide uniformly dispersed throughout. The production of the granules comprises the steps of sending the cellulose together with a tertiary amine oxide powder having a water content of 5 to 17% by weight to a mill equipped with blade blades and grinding and kneading the solid mixture in the mill. including. Completely agglomerates both cellulose and tertiary amine oxide powder without dissolving the cellulose,
Grind the solid mixture at a temperature sufficient to half melt. Therefore, the temperature is below the melting temperature of the tertiary amine oxide powder so that it will be in an interdiffusion state without dissolution of the cellulose. Pre-dope granules are solid composites of cellulose that are not dissolved in amine oxide.

According to one embodiment of the present invention, there is provided a method of making pre-doped granules of cellulose and a tertiary amine oxide dispersed therein. The method according to the invention comprises the steps of: (a) sending the cellulose to a mill together with a tertiary amine oxide powder having a water content of 5 to 17% by weight, and (b) in the mill without the dissolution of the cellulose Complete aggregation of amine oxide powder and cellulose,
Milling and kneading the resulting solid mixture while maintaining a temperature sufficient to cause half-melting.

In the method of the present invention, the tertiary amine oxide powder is homogeneously dispersed throughout the cellulose by mixing the tertiary amine oxide powder component having a specific water content and the cellulose component in a mill. It uses a tertiary amine oxide powder having a water content of 5 to 17% by weight, which is sufficient to completely agglomerate and semi-melt the powder and the cellulose without dissolving the cellulose. Achieved by heating at temperature.

The pre-doped granules thus obtained are stored without exposure to moisture until formed into cellulosic articles such as fibers and membranes. If desired, the pre-dope granules may be sent to an extruder to form a dope solution of cellulose for use in spinning.

Preferably, the tertiary amine oxide used in the practice of this invention is N-methylmorpholine-N-oxide, N-methylpyrrolidine-N-oxide, N-methylpiperidine-N-oxide, N, N. -Dimethylethanolamine-N-oxide, N, N-dimethylbenzylamine-N-oxide, N, N-dimethylcyclohexylamine-N-oxide and the like or mixtures thereof. Generally, the amount of cellulose sent to the mill is not more than 45% by weight, preferably 6 to 45% by weight, based on the total weight of the mixture of cellulose and tertiary amine oxide.

The temperature is controlled by adjusting frictional heat and cooling water. The milling time should be adjusted to achieve the desired results as described herein. The preferred temperature range in the mill depends on the cellulose content, but is typically 40-100 ° C.
The kneading may be carried out at any speed with the blade blade of the mill, as long as the tertiary amine oxide is homogeneously dispersed in the cellulose to form pre-doped granules. 50
Kneading at 0-10,000 rpm gave the desired results.

In the pre-dope granules according to the invention, the tertiary amine oxide is dispersed in the cellulose fibrils, so that the pre-dope granules can be obtained in a short time during the passage through the extruder with a conventional outlet. A cellulose dope solution for spinning can be formed by completely dissolving the dope. According to conventional methods, either a solution of cellulose or solid chips of the solution in which the cellulose is completely dissolved in the amine oxide are transferred directly to the extruder. In contrast, according to the present method, as described below with reference to the accompanying drawings, pelletized pre-doped granules consisting of cellulose and amine oxide, in which amine oxide and cellulose are semi-molten, are heated to a predetermined temperature. It can be transferred directly from the mill to the extruder. Thus, the method of the present invention is quite different from prior art methods.

The method of the present invention has the following important advantages:

First, by minimizing the time to dissolve a large amount of cellulose in the tertiary amine oxide, it is possible to prevent the decomposition of cellulose and tertiary amine oxide and the discoloration of the resulting solution, The mechanical properties of fibers and membranes are improved. The cellulose dope solution produced by the method of the present invention is less susceptible to thermal discoloration as compared to the discoloration produced by conventional methods. Furthermore, the molecular weight of the cellulose in the solution remains substantially unchanged. As a result, it is not necessary to use antioxidants such as propyl gallate to maintain the molecular weight of cellulose.

Secondly, there is no need to prepare solid chips, since the pre-dope granules can be transferred directly into the extruder. The pre-dope granules can also be used in conventional extruders.

Finally, a dope solution of cellulose with a high solids content can easily be obtained. The preparation of a cellulose solution having a high solid content by the conventional method requires severe conditions that cause the cellulose to be broken down, such as high temperature, long time, and vigorous stirring. But,
According to the invention, the use of solid / solid phase milling does not require such stringent conditions. Also, in the process of the present invention, the pre-dope granules completely melt in a short time during passage through the extruder, even when their cellulose content is high (up to 45% by weight).

The present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a method for producing pre-doped granules of cellulose and tertiary amine oxide powder. According to this method, cellulose is contained in an amount of 5 to 17% by weight.
Sent to the mill with a tertiary amine oxide powder having a water content of. The solid mixture obtained is ground and kneaded to form pre-doped granules. Then, the pre-dope granules thus obtained are melted in an extruder to form a cellulose dope solution for use in spinning, and the obtained dope solution is extruded through a spinneret or die.

FIG. 2 schematically shows the structure of the method shown in FIG. 1 and an apparatus for carrying out the method. Cellulose is cut into equal-sized sheets by a cutting machine, and the cut pieces are introduced into a mill 1 through a supply port 2 together with a tertiary amine oxide powder having a water content of 5 to 17% by weight. The amount of cellulose fed in is up to 45% by weight, preferably 6-45% by weight. The obtained solid mixture is passed through a blade 3 to 500-10,000 rpm.
And homogenize. At this time, the temperature controller 4 provided on the outer wall of the mill 1 is maintained at 40 to 100 ° C.

During the milling and kneading steps, the tertiary amine oxide powder is homogeneously dispersed in the cellulose. Further, since the tertiary amine oxide powder is infiltrated into the undissolved cellulose fibrils to be semi-melted, a homogeneous solid granule composite, that is, a pre-doped granule can be obtained.

The pre-dope granules are taken out of the mill 1 via the suction port 5 by the suction device 6. The obtained pre-dope granules are packed and stored so as not to be exposed to moisture. Alternatively, the cellulose solution for use in spinning can be continuously prepared by directly connecting the mill 1 as shown in FIG. 2 to the hopper of the extruder.

FIG. 3 is a photomicrograph obtained through a microscope equipped with a polarimeter, showing the pre-doped granules produced in Mill 1. FIG. 4 is a photomicrograph of a dope solution of cellulose produced by passing the pre-dope granules through an extruder at a given temperature.

When observing the pre-doped granules with a microscope equipped with an polarimeter, the cellulose fibrils are seen in an undissolved state. However, since the tertiary amine oxide powder is homogeneously dispersed in the cellulose fibrils, the tertiary amine-N-
No oxide particles are found in the pre-doped granules. In order to melt the pre-dope granules,
It is passed through a single-screw extruder equipped with an outlet having an L / D ratio of 20 in mm. The dope solution thus obtained can be observed under a microscope to determine if the pre-dope granules are completely molten.

[0039]

The present invention will be described in more detail by the following examples. These examples do not limit the invention.

Example 1 N containing 12.5% by weight of water, as shown in FIG.
-Methylmorpholine-N-oxide (NMMO) granules 8
5% by weight was introduced into the mill, and the weight average polymerization degree (DP _w ) was 9
5 x 5 cm cellulose pulp sheet (Rayonex-P
) 15% by weight was added thereto. The inner wall of the mill was maintained at 50 ° C. by temperature controller 4 and the resulting mixture was mixed at that same temperature and 2,500 rpm to form pre-doped granules.

The pre-dope granules obtained were introduced into a single-screw extruder with a diameter of 25 mm and an L / D ratio of 20, equipped with an outlet. After adjusting the temperature of the die area of the extruder to 90 ° C., a dope solution was prepared under the processing conditions shown in Table 1 below. A portion of the resulting solution was examined by microscopy for melting of the cellulose and discoloration of the resulting solution. At that time, the temperatures of the solid phase moving region, the melting region and the liquid phase moving region in the extruder are 50 ° C. and 90 ° C.
C and 100C were set. The degree of dissolution is shown in Table 1 below.
Shown in

The pre-dope granules which were not passed through the extruder were observed in the same manner as described above. as a result,
It was confirmed that the cellulose remained undissolved in the mixture and the amine oxide particles were not observed as they had penetrated into the cellulose. In addition, it was observed that the pre-dope granules passed through the extruder were in the liquid phase, in which the cellulose was completely dissolved.

The dope solution thus obtained was immersed in water to completely remove the solvent. The molecular weight of the cellulose was calculated by placing about 3 g of the residue in a vacuum drier for 1 hour, where the inherent viscosity was measured using a 0.5 M cuene solution. It was found to have a reduced molecular weight than in conventional solutions.

[0044]

[Table 1]

Example 2 In this example, the temperatures of the extruder die, solid phase transfer zone, dissolution zone and liquid phase transfer zone were 110 ° C. and 50 ° C., respectively.
C., 110.degree. C. and 110.degree. C., except that the dope solution of cellulose was obtained under the same conditions as described in Example 1.

The obtained dope solution was extruded with a metering pump and a spinneret (diameter 0.5 mm, L / D).
It was extruded into the coagulant (distilled water) at a rate of 0.6 g / min. The fibers thus formed were wound at 100 m and 200 m / min, respectively. The fibers thus solidified were washed with water and dried, and their mechanical properties were examined. The results are shown in Table 2 below.

[0047]

[Table 2]

As can be seen from Table 2, no cellulose fibrils were found in the solution under this treatment condition.
However, as the temperature in the extruder increased and the residence time of the pre-dope granules increased, the color of the solution gradually changed to brown due to the decomposition of the solution.

Example 3 As shown in FIG. 2, 75% by weight of N-methylmorpholine-N-oxide powder containing 10% by weight of water was added to a mill 1.
Was introduced. Cellulose pulp sheet (Cellunier F)
25 wt% was added there. The temperature of the inner wall of the mill was maintained at 60 ° C. by the temperature controller 4, and the mixture was heated to
Mix at 000 rpm to form pre-doped granules. The obtained granules were treated under the conditions described in Example 2,
A dope solution of cellulose was prepared. No cellulose fibrils were found in the solution.

The dope solution thus obtained was subjected to the same procedure as described in Example 2 by using an extruder equipped with a metering pump and a spinneret (caliber 0.25 mm, L / D).
5, 24 holes) and 0.2 g / min of about 20% by weight of an aqueous solution of coagulant (N-methylmorpholine-N-oxide).
Including). The fibers thus formed were wound at 100 m / min. Wash the solidified fiber with water,
It was dried and its mechanical properties were inspected. The results are shown in Table 3 below.
Shown in

[0051]

[Table 3]

Example 4 80% by weight of N-methylmorpholine-N-oxide powder containing 10% by weight of water in a mill 1 as shown in FIG.
Was introduced and 20% by weight of cotton pulp (DP600) was added thereto. The inner wall of the mill was maintained at 60 ° C and the mixture was mixed at that temperature and 4,000 rpm to form pre-doped granules. The resulting granules were processed under the same conditions described in Example 2 except that the temperature of the extruder die area was changed to 120 ° C. to obtain a dope solution of cellulose. No cellulose fibrils were found in the solution.

The dope solution thus obtained was subjected to the same treatment as described in Example 2 by means of an extruder equipped with a metering pump and a spinneret (caliber 0.25 mm, L / D).
An aqueous solution of coagulant (N-methylmorpholine-N-oxide of about 20% by weight) at 0.15 g per minute through 3, 24 holes).
Including). The fibers thus obtained were wound at 100 m / min. The coagulated fiber was washed with water, dried and examined for its mechanical properties. The results are shown in Table 4 below.

[0054]

[Table 4]

Example 5 65% by weight of N-methylmorpholine-N-oxide powder containing 6% by weight of water were introduced into a mill 1 as shown in FIG. Cellulose pulp sheet (DP200) 35% by weight
Was added there. The inner wall of the mill was maintained at 80 ° C and the mixture was mixed at that temperature and 5,000 rpm to form pre-doped granules. The obtained granules were treated under the same conditions as described in Example 1 to obtain a dope solution of cellulose.

A small amount of cellulose fibrils were found in the cellulose solution after passing through the extruder at 30 rpm and 50 rpm. However, this fibril could be easily removed by a filter.

Example 6 N-methylmorpholine-N-oxide powder containing 9% by weight of water, N, N-dimethylethanolamine-N-oxide containing 8% by weight of water and 7% by weight of water, Other tertiary amine oxide powders shown in Table 5 below were added
It was introduced together with 10% by weight of cellulose pulp sheet (Cellunier Q) into mill 1 maintained at 60 ° C. to form pelletized pre-dope granules. The resulting pre-dope granules were processed under the same conditions as described in Example 1, except that the extruder die temperature was changed to 100 ° C and the screw rotation speed was changed to 20 rpm.

No cellulose fibrils were found in the cellulose solution after passing through the extruder. The results are shown in Table 5 below.

[0059]

[Table 5]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a procedure of a method for producing a cellulose solution according to the present invention.

FIG. 2 shows the structure of a mill with blade blades for grinding cellulose with tertiary amine oxide powder.

FIG. 3 is a micrograph of pre-doped granules of cellulose and tertiary amine oxide.

FIG. 4 is a micrograph of a dope solution of cellulose produced by passing the pre-dope granules through an extruder.

[Explanation of symbols]

 1 mil 2 supply port 3 blade type blade 4 temperature controller 5 suction port 6 suction device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location D01D 5/06 D01D 5/06 Z D01F 2/00 D01F 2/00 Z (72) Inventor Kim Dong Fu No. 78, No. 78, Jamdo 2-dong, Dongjak-gu, Seoul, Republic of Seoul, Korea (72) Inventor Park Jong-Hu, No. 188, No. 188, Huijeong-dong, Dongdaemun-gu, Seoul, Republic of Korea (56) References JP-B-55-41691 (JP) , B2) Japanese Patent Publication Sho 55-41693 (JP, B2)

Claims (5)

(57) [Claims] 1. A method for producing pre-doped granules of cellulose and a tertiary amine oxide powder dispersed throughout, comprising: (a) cellulose together with a tertiary amine oxide powder having a water content of 5 to 17% by weight. And (b) maintaining the temperature in the mill at a temperature sufficient to completely agglomerate and semi-melt both the cellulose and the tertiary amine oxide powder without dissolving the cellulose. Pulverizing and kneading the obtained solid mixture. 2. The tertiary amine oxide is N-methylmorpholine-N-oxide, N-methylpyrrolidine-N-oxide, N-methylpiperidine-N-oxide, N, N.
A process according to claim 1 selected from the group consisting of: -dimethylbenzylamine-N-oxide, N, N-dimethylethanolamine-N-oxide, N, N-dimethylcyclohexylamine-N-oxide or mixtures thereof. . 3. The method according to claim 1, wherein the cellulose is used in an amount of 6 to 45% by weight, based on the total weight of cellulose and tertiary amine oxide. 4. The method according to claim 1, wherein the crushing and kneading are carried out at 40 to 100 ° C. 5. Pre-doped granules of cellulose and tertiary amine oxides, which can be produced by the process according to claim 1.