JP3267781B2 - Method for producing regenerated cellulose molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a regenerated cellulose molded article, and more specifically, to obtain a regenerated cellulose molded article by an aqueous coagulation method using a stock solution using a tertiary amine oxide of cellulose and an aqueous solvent. The present invention relates to an industrially advantageous method for producing a regenerated cellulose molded article having excellent mechanical properties by using a novel aqueous coagulation liquid and further performing a heat treatment.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a regenerated cellulose molded article, cellulose or a derivative thereof is dissolved in a solvent,
A method for obtaining a molded product such as a fiber or a film from the obtained solution is known. As such a method, there are a viscose method and a copper-ammonia method. However, these methods involve complicated chemical reactions, not only require long steps, but also pose a serious problem in terms of various environmental pollutions.

In recent years, studies on solvents for cellulose have been advanced, and some solvents having strong dissolving power for cellulose have been found. As a result, as in the case of a synthetic resin, a molding stock solution can be obtained by simply dissolving cellulose in a solvent. Among these solvents, tertiary amine oxides, especially N-methylmorpholine-N-oxide, are specific and excellent solvents for cellulose, and there are several methods for producing regenerated cellulose fibers and films using the same. Proposed. Above all, for example, the method disclosed in JP-B-60-28848, that is, cellulose dissolved in a mixed solvent consisting of N-methylmorpholine-N-oxide and water,
A method for producing a regenerated cellulose molded article by a so-called dry-jet wet spinning method using water as a coagulant has attracted the most attention in practical use. According to the method, the solvent system is very simple, substantially only N-methylmorpholine-N-oxide, the recovery step can be simplified, and a molding solution having a high cellulose concentration of 10 to 40% by weight can be used. And, conventionally known dry jet wet spinning method can be easily applied, water is used for the coagulation liquid, molding, not only is convenient in the recovery step, but also virtually no side reactions in the process, pollution-free It has features such as a close manufacturing process, and some have started production on an industrial scale.

[0004] However, according to this method, when the drawing is performed in a non-solidified state in the process of forming a fiber or a film using a simple dry-jet wet spinning method, a molded article having mechanical properties that can withstand practical use is obtained. It is difficult to get. Therefore, in order to improve the mechanical properties of a molded product, a spinning device is generally devised so that coagulation and stretching are performed simultaneously. For such purposes,
For example, Japanese Patent Publication No. Sho 60-28848 discloses an improved dry jet in which a water supply roller is provided between a spinneret and a water surface to supply a small amount of water to the surface of a spinning stock solution to be stretched and to coagulate the spinning stock solution. There has been disclosed a wet spinning apparatus, an improved dry jet wet spinning apparatus, and the like, in which a mist chamber is provided, water is supplied in the form of mist from a conduit, and drawing is performed while solidifying a spinning solution. According to the apparatus, not only is the fiber production process extremely simple, but also it is possible to obtain regenerated cellulose fibers having mechanical properties comparable to conventionally known high-strength rayon by performing high-speed spinning at a spinning speed of several hundred meters / minute. it can. However, the mechanical properties of the regenerated cellulose molded article are improved as the draw ratio is improved, that is, as the spinning and film forming speeds are increased. It is necessary to increase the film speed, and the film is coagulated at the same time as the stretching at a high speed. Therefore, there is a drawback that there is a certain limit in equipment or operation.

In order to improve such disadvantages, a conventionally known ordinary dry-jet wet spinning method is used. In particular, as a method for improving the mechanical properties of regenerated cellulose fiber without increasing the spinning speed, a specific additive is used as a spinning dope. H. Chanzy et al. Proposed a method of adding
lymer 1990 31 400). According to this method, a conventionally known dry spinning solution is obtained by using a spinning solution obtained by adding n-propyl gallate and ammonium chloride or calcium chloride to a cellulose solution obtained from an N-methylmorpholine-N-oxide-water-based mixed solvent. By the wet wet spinning method, a regenerated cellulose fiber having excellent strength can be easily obtained at a relatively low spinning speed of 20 to 200 m / min. N-Propyl gallate is known as an antioxidant for cellulose (for example, Japanese Patent Publication No. 3-29).
No. 819), and therefore, a feature of the method is that a regenerated cellulose fiber having excellent mechanical properties is obtained by using a spinning solution to which ammonium chloride or calcium chloride is added. In particular, it is shown that the addition of ammonium chloride improves the mechanical properties, particularly the strength, up to 1.4 to 1.8 times as compared to the case where no ammonium chloride is added. However, the fibers obtained by this method have strength but no elongation. In other words, there is a fatal problem of hard but brittle fibers, and the practical range is extremely limited.The added ammonium chloride or calcium chloride also acts as a coagulation accelerator for cellulose, stabilizing the spinning solution over time. From a gender perspective,
Not preferred.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a special spinning or film forming apparatus for obtaining a regenerated cellulose molded product by an aqueous coagulation method using a stock solution using a tertiary amine oxide of cellulose and an aqueous solvent. It is an object of the present invention to provide a method for producing a regenerated cellulose molded article having excellent mechanical properties even at a relatively low spinning speed without the need for the above method.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, a cellulose solution dissolved in a tertiary amine oxide-water-based mixed solvent was used as a stock solution, and water was used as a coagulation bath. In a conventionally known dry-jet wet spinning method or a wet spinning method, a substance capable of changing the coagulation action of a coagulation bath, a water-soluble neutral organic compound, a water-soluble inorganic neutral salt, a water-soluble caustic alkali, a water-soluble acid Coagulation using a coagulation solution containing, and then drying and heat treatment under appropriate conditions, without the need for excessive elongation, regeneration that dramatically improved not only strength but also elongation Finding the surprising fact that a cellulose molded article can be obtained,
By appropriately selecting the type of the compound to be added and the drying and heat treatment conditions, it is possible to easily produce a regenerated cellulose molded article having a wide range of practical use and mechanical properties according to the purpose by a method extremely practically advantageous. The inventors have found and completed the present invention. That is, the present invention provides an industrially advantageous and simple method for producing a cellulose molded article having excellent mechanical properties without using a special spinning or film-forming apparatus and using a conventionally known apparatus. Things.

The first gist of the present invention resides in that an aqueous solution to which a substance capable of changing the coagulation action of a coagulation bath (hereinafter also referred to as an additive) is added as a coagulation liquid. When the aqueous solution to which the additive is added is spun as a coagulating liquid, the osmotic pressure of the water of the coagulating liquid with respect to the liquid yarn (filament spinning liquid discharged from the spinning nozzle) in the coagulating bath changes. That is, it is considered that coagulation due to the diffusion of water into the liquid yarn is suppressed, and the formation of the yarn by so-called concentrated coagulation is promoted by the diffusion of the solvent from the liquid yarn to the coagulation bath. Here, a strong alkali or a strong acid may have a hydration effect on cellulose, but considering the effects of other neutral substances, it is presumed that the effect of the change in osmotic pressure of water is mainly. There is no difference in the cross-sectional shape of the yarn irrespective of the presence or absence of the additive and the type of the additive. By using the additive, bonding between molecules or between higher-order structures (precipitated particle structure formed in the coagulation process) It was found that the properties and homogeneity were improved, and the denseness of the fiber structure was improved.

Examples of usable additives include water-soluble neutral organic compounds, water-soluble inorganic neutral salts, water-soluble caustic alkalis and water-soluble acids. Preferably, the water-soluble organic compounds are urea, pyrrolidone, ε- Caprolactam, as water-soluble inorganic neutral salts, ammonium nitrate, ammonium chloride, sodium sulfate, sodium chloride, potassium rhodanate, sodium rhodanate, magnesium chloride, zinc chloride, calcium chloride, tin chloride; and water-soluble caustic as water Examples of water-soluble acids include sodium oxide, potassium hydroxide, calcium hydroxide, and zinc hydroxide, and examples of the water-soluble acids include sulfuric acid, nitric acid, phosphoric acid, formic acid, and monochloroacetic acid. The concentration of the various additives to be added to the coagulation liquid varies depending on the composition of the forming stock solution, stretching conditions, drying and heat treatment conditions, or the use of the molded product, and cannot be specified differently, but generally, about 0.1 to 10% by weight is sufficient. Express its effect. In addition, although it differs depending on the heat treatment conditions and the like, generally, when strength is required, a water-soluble inorganic neutral salt such as sodium sulfate is used. When elongation is required, a water-soluble caustic such as sodium hydroxide or sulfuric acid is used. It is preferable to use a water-soluble acid such as urea or a water-soluble neutral organic compound such as urea when an intermediate is required.

Next, a second gist of the present invention lies in that the wet molded product after solidification is dried and heat-treated under appropriate conditions.
That is, by drying and heat-treating the wet molded product under appropriate conditions, the denseness of the fiber structure is dramatically improved,
In other words, the drying and heat treatment temperature plays a very important role in the densification of the fiber structure, and selection of appropriate drying and heat treatment conditions is extremely effective for the densification and homogenization of the fiber structure of the regenerated cellulose molded product. Was found. The drying / heat treatment temperature varies depending on the composition of the coagulating bath used, the purpose of use of the molded product, and the like, but is higher than the glass transition temperature of cellulose (referred to as -30C to 160C) by 15%.
If the temperature is in the range of from high temperature to 20 ° C. to the thermal decomposition temperature or less, the purpose is satisfied.
About 150 ° C. or less is appropriate. However, during drying and heat treatment, it is necessary to sufficiently wash with water to remove the solvent and the coagulating liquid, but the drying and heat treatment apparatus and method are not particularly limited. For example, dry heat treatment in a relaxed state is sufficient. The effect can be exhibited.

In carrying out the present invention, cellulose is dissolved in a mixed solvent comprising a tertiary amine oxide and water, but the cellulose used is not particularly limited, and pulp usually used for industrial use is sufficient. . The method for dissolving cellulose is not particularly limited, either, and cellulose may be dissolved in a mixed solvent comprising a tertiary amine oxide and water according to a conventionally known method. These methods are, for example, various methods and apparatuses described in JP-B-60-28848, but are not limited to the dissolving method or apparatus. As the tertiary amine oxide used in the present invention, any tertiary amine oxide can be used as long as it dissolves cellulose and mixes it with water and is stable to water. For example, dimethylethanolamine oxide, triethylamine oxide, certain monocyclic N-methylamine-N-oxides such as N-methylmorpholine-N-oxide, N-methylpiperidine-
N-oxide, N-methylpyrrolidine-N-oxide and other cyclic amine oxides in which the amine oxide group is outside the ring, such as dimethylhexylamine
N-oxide and the like can be mentioned, but N-methylmorpholine-N-oxide is preferable from a practical viewpoint. The composition of the cellulose solution varies depending on the type of the cellulose, the type of the solvent, the molding apparatus, the molding conditions and the like, and is not particularly limited. In general, the cellulose is about 5% to 40% by weight, and the tertiary amine oxide is about 90% to 40% by weight. %, 5 to about 20% by weight of water.

In the present invention, it is optional to add various additives for the purpose of preventing cellulose degradation during or after dissolution, for example, remarkable collapse or discoloration of cellulose chains. Examples of additives to be added for these purposes include compounds disclosed in JP-B-3-29819, for example, L (+) ascorbic acid, hydroquinone,
Examples thereof include isopropyl gallate and the like.

The obtained cellulose solution is generally kept at 70 ° C. to 150 ° C., preferably 90 ° C. to 130 ° C., and is first formed into a fiber or film by spinning or extrusion in air or in an aqueous solution containing the aforementioned additives. The cellulose is then stretched during or after coagulation to improve the mechanical properties of the molded article. The cellulose solution extruded from a molding nozzle or die is generally stretched by being stretched at a speed higher than its extrusion speed, but the degree of stretching is determined by the spinning (or film forming) stretching ratio, that is, the linear speed of the solidified molded product. It is determined by the value obtained by dividing by the linear velocity at which the liquid is discharged from the nozzle or die. Tokunosho 6
The method described in JP-A-28848 is based on the fact that cellulose molecules are oriented in a solution by stretching before coagulation, and the properties of the obtained cellulose are improved before complete coagulation of cellulose. Therefore, high stretching before complete coagulation is essential for improving the mechanical properties of regenerated cellulose,
Usually, a high stretching ratio of 3 or more, especially a stretching ratio close to 20 to 30 is required. In the case of the present invention, the mechanism of expressing the mechanical properties of the regenerated cellulose is different from such known techniques,
It is based largely on the selection of the composition of the coagulation solution as well as the improvement of the mechanical properties by drying and heat treatment, and does not require the above-mentioned conditions, that is, high stretching before complete coagulation of cellulose. Therefore, it can be easily understood that the method of the present invention provides a method for producing a regenerated cellulose molded article which is greatly improved in terms of equipment and operation management. Of course, depending on the purpose, even if the molded article obtained by the conventional technique as described above is completely coagulated by the coagulation bath of the present invention and further subjected to drying and heat treatment, it does not contradict the gist of the present invention. That is, it may be stretched while solidifying, or stretching after solidification is not contrary to the gist of the present invention, and the effect of the present invention is compensated by adopting a solidification and stretching process according to the purpose. What you do is optional.

[0014]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but it is needless to point out that the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In addition,
In the following examples, percentages and parts mean weight percentages and parts by weight. Example 1 [Examples: Sample 1-1 to Sample 4-4; Comparative Examples 1 to 4] 840 parts of N-methylmorpholine-N-oxide (manufactured by Nippon Emulsifier Co., Ltd.) containing 13.3% of water and water Wood pulp containing about 6.0 percent (KS
100 parts of powder (produced by Kojin Co., Ltd.) were charged into a jacketed Werner type pulverizer, and stirred at 90 ° C. for 2 hours to prepare a solution having a cellulose content of about 10%. The solution was spun by dry jet wet spinning using this solution to obtain a regenerated cellulose fiber. Air gap is 10mm, spinning temperature is 100 ℃, nozzle is 0.10mmφ
× 20 holes, coagulation bath temperature was 20 ° C. As examples, the coagulation bath was a 10% aqueous urea solution for samples 1-1, 2, 3 and 4, and samples 1 to 2 were for samples 2-1, 2, 3 and 4.
0% ammonium nitrate aqueous solution was added to Sample 3-1.
2, 3 and 4 contain 9% aqueous sodium sulfate solution,
Samples 4-1, 2, 3 and 4 were spun using 5% aqueous sodium hydroxide solution for the coagulation bath, respectively. In Comparative Examples 1, 2, 3, and 4, spinning was performed using water as a coagulation bath.
The spinning draft (the ratio of the average flow velocity (v ₀ ) of the spinning dope passing through the spinning nozzle to the winding speed (v ₁ ) of the coagulated yarn) during spinning was 1.01. Here, it is noted that spinning is performed in a region where the spinning draft is low. The obtained yarn (coagulated yarn) was washed with water to remove the solvent, and then dried and heat-treated. Drying and heat treatment temperatures were room temperature (19 ° C to 21 ° C), 100 ° C, 150 ° C, and 200 ° C. Drying and heat treatment were performed in a relaxed state, and shrinkage was free. The properties of the regenerated cellulose fibers thus obtained are summarized in Table 1. The effects of the additives added to the coagulation bath are clear from Samples 1-1, 2, 3 and 4 in Table 1 and Comparative Example 1. Samples 2-1, 2,
As is clear from Comparative Examples 2 and 3 and 4, Samples 3-1, 2, 3 and 4 and Comparative Example 3, and Samples 4-1, 2, 3 and 4 and Comparative Example 4, the appropriate drying and heat treatment temperature is fiber. It can be seen that the mechanical properties of the compound are greatly improved. The regenerated cellulose fibers obtained from the conventional water-coagulation-based bath decreased the elongation when the strength was increased, and decreased when the elongation was increased. That is, in each case, the toughness was only low, but the regenerated cellulose fiber obtained by the method of the present invention generally has a large toughness, and has extremely advantageous properties in practical use with a balance between strength and elongation. It can be said.

Example 2 Wood pulp (K) containing 850 parts of N-methylmorpholine-N-oxide (manufactured by Nippon Emulsifier Co., Ltd.) containing 13.3% of water and about 6.0% of water.
S powder (produced by Kojin Co., Ltd.) (160 parts) was charged into a jacketed Werner type pulverizer, and stirred at 90 ° C. for 2 hours to prepare a solution having a cellulose content of about 15%. The solution was spun by dry jet wet spinning using this solution to obtain a regenerated cellulose fiber. Air gap 35mm, spinning temperature 120 ° C, nozzle 0.085m
mφ × 17 holes, coagulation bath temperature was 20 ° C. Coagulation bath with sodium sulfate 7% aqueous solution, magnesium chloride 5%
An aqueous solution and a 3% aqueous solution of sulfuric acid were used, and a water bath was used as a comparative object. The obtained sample was sufficiently washed with water to remove the solvent, and then subjected to a dry heat treatment at 120 ° C. for 10 minutes. The results of fiber properties of the dried and heat-treated product are shown below. Coagulation bath Fineness (d) Strength (g / d) Elongation (%) Young's modulus (g / d) 9% aqueous sodium sulfate solution 3.4 3.5 25 120 120 9% aqueous sodium sulfate solution 1.7 3.5 25 130 Magnesium chloride 5% aqueous solution 3.4 2.7 23.4 100 Magnesium chloride 5% aqueous solution 1.7 2.5 24.0 105 5% sulfuric acid aqueous solution 3.4 2.7 23.4 103 5% aqueous sulfuric acid solution 1. 7 2.5 21.0 100 Water 3.4 1.1 10.4 95 Water 1.7 1.0 9.0 85 Based on the above results, the present invention is compared with the case where water as a comparative example is used as a coagulation bath. It is noted that the fibers have excellent mechanical properties when spun by the method. It is particularly effective for fine fibers.

Example 3 A spinning solution having a cellulose content of about 15 percent was prepared in the same manner as in Example 2. The solution was spun by dry jet wet spinning using this solution to obtain a regenerated cellulose fiber. Air gap is 5mm, spinning temperature is 10
The test was performed at 0 ° C., a nozzle of 0.35 mmφ × 17 holes, and a coagulation bath temperature of 20 ° C. Spin draft from 0.3 to 5.0
Changed in range. Coagulation bath is 7% aqueous solution of sodium sulfate,
A 10% aqueous solution of sodium rhodanate and a 7% aqueous solution of ε-caprolactam were used, and a water bath was used for comparison. The obtained fiber is sufficiently washed with water to remove the solvent, and then at 150 ° C.
A drying heat treatment was performed for 5 minutes. The results of fiber properties of the dried and heat-treated product are shown below. Coagulation bath: 7% aqueous solution of sodium sulfate Spinning draft Fineness (d) Strength (g / d) Elongation (%) Young's modulus (g / d) 0.3 3.1 4.0 14.0 130 1.0 3. 1 4.1 13.0 145 2.5 3.1 4.3 10.0 150 150 4.0 3.1 4.5 9.5 155 5.0 3.1 3.1 4.5 7.5 160 Coagulation bath: 10% aqueous solution of sodium rhodanate Spinning draft Fineness (d) Strength (g / d) Elongation (%) Young's modulus (g / d) 0.3 3.1 3.9 14.0 110 1.0 3.1 3 9.9 11.0 130 2.5 3.1 4.0 9.0 140 4.0 3.1 4.2 7.5 7.5 147 5.0 3.1 4.3 6.5 155 Coagulation bath: ε- 7% aqueous solution of caprolactam Spinning draft Fineness (d) Strength (g / d) Elongation (%) Young's modulus (g / d) 0.3 3.1 3.0 13.0 95 1.0 3.1 3.1 11.0 100 2.5 3 1 3.4 8.0 120 4.0 3.1 4.2 6.5 127 5.0 3.1 4.1 4.3 5.8 135 Coagulation bath: water (comparative example) Spinning draft Fineness (d) Strength ( g / d) Elongation (%) Young's modulus (g / d) 0.3 3.1 1.9 7.0 95 1.0 3.1 3.1 1.9 6.5 100 2.5 3.1 2. 0 6.0 103 4.0 3.1 2.1 4.5 4.5 107 5.0 3.1 2.1 3.8 108 From the above results, the present invention is compared with a comparative example in which water is used as a coagulation bath. It is noted that when the fiber is spun by the method described above, the mechanical properties of the fiber are excellent even in a region where the spinning draft is low. Also, even if the spinning draft increases, the rate of decrease in the fiber elongation at cutting is small.

Example 4 A spinning solution having a cellulose content of about 10 percent was prepared in the same manner as in Example 1. The solution was spun by dry jet wet spinning using this solution to obtain a regenerated cellulose fiber. Air gap 3mm, spinning temperature 100
C., the nozzle was 0.10 mmφ × 20 holes, and the coagulation bath temperature was 20 ° C. 9% aqueous solution of sodium sulfate in coagulation bath,
A water bath was used as a comparative object using a 10% aqueous urea solution.
The obtained fiber was sufficiently washed with water to remove the solvent, and then subjected to a drying heat treatment at each temperature for 10 minutes. The results of fiber properties of the dried and heat-treated product are shown below. Coagulation bath: 9% aqueous solution of sodium sulfate Drying temperature Fineness (d) Strength (g / d) Elongation (%) Young's modulus (g / d) Room temperature 2.5 2.6 33.0 85 100 ° C 2.5 3. 1 30.0 120 150 ° C 2.5 4.2 12.5 150 200 ° C 2.5 2.0 10.5 70 250 ° C 2.5 0.8 3.5 20 Coagulation bath: 10% urea aqueous solution Drying temperature Fineness (d) Strength (g / d) Elongation (%) Young's modulus (g / d) Room temperature 2.5 1.7 25.0 50 100 ° C 2.5 2.5 22.1 90 150 ° C 2.5 3.0 12.0 115 200 ° C 2.5 1.4 5.6 60 250 ° C 2.5 0.5 1.5 18 Coagulation bath: water (comparative example) Drying temperature Fineness (d) Strength (g / d) ) Elongation (%) Young's modulus (g / d) Room temperature 2.5 0.9 18.3 55 100 ° C 2.5 1.2 10.9 80 150 ° C 2.5 2.0 7.0 95 95 ° C 2.50 3.9 3.8 67 250 ° C 2.5 0.5 1.2 17

[0018]

As described above, according to the present invention, a special spinning or film-forming apparatus is not required, and excellent mechanical properties which cannot be achieved by the prior art can be obtained by using a conventionally known apparatus. It is possible to easily produce a regenerated cellulose molded article, and its practical significance is extremely large.

[Table 1]

Claims (6)

(57) [Claims] When a cellulose solution using a tertiary amine oxide-water mixed solvent is formed by a dry-jet wet spinning method or a wet spinning method, a coagulating liquid is formed of a water-soluble neutral organic compound or a water-soluble inorganic neutral salt. A method for producing a regenerated cellulose molded article, which is an aqueous solution containing at least one substance selected from a water-soluble caustic alkali and a water-soluble acid, and wherein the obtained solidified molded article is heat-treated. 2. The method according to claim 1, wherein the tertiary amine oxide is N-methylmorpholine-N-oxide. 3. The water-soluble neutral organic compound is urea, pyrrolidone, ε-caprolactam, and the water-soluble inorganic neutral salt is ammonium nitrate, ammonium chloride, sodium sulfate, sodium chloride, potassium rhodanate, sodium rhodanate, magnesium chloride, chloride. Zinc, calcium chloride, tin chloride,
The regenerated cellulose molded article according to claim 1, wherein the water-soluble caustic is sodium hydroxide, potassium hydroxide, calcium hydroxide, zinc hydroxide, and the water-soluble acid is sulfuric acid, nitric acid, phosphoric acid, formic acid, or monochloroacetic acid. Manufacturing method. 4. The heat treatment method is performed at a temperature of 100 ° C. or more and 200
4. The method for producing a regenerated cellulose molded article according to claim 1, wherein the dry heat treatment is performed at a temperature of not more than ℃. 5. The method for producing a regenerated cellulose molded article according to claim 1, wherein the regenerated cellulose molded article is a fiber. 6. The method for producing a regenerated cellulose molded article according to claim 1, wherein the regenerated cellulose molded article is a film.