JP3157224B2 - Manufacturing method of cellulose molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulose molded product represented by a film, a fiber (including a hollow fiber or a non-woven fabric), a powder, etc., by a dope comprising a substantially alkali-soluble cellulose and an aqueous alkali solution. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art In general, a molded product of cellulose (fiber, film, powder) is produced by dissolving cellulose in a solvent by a certain method and pouring the solution into a non-solvent medium. At present, a method for dissolving cellulose which is industrially used for the above-mentioned purpose is a method in which so-called cellulose, which was already discovered almost 100 years ago (late 1890s), is treated with alkali to form alkali cellulose. There are only two methods, the method of reacting carbon sulfide and then dissolving it in alkali (viscose method) and the method of dissolving cellulose in copper ammonia solution (copper copper method). Interesting in that it is a technology that was discovered before The cellulose in the solution obtained by these methods is not dissolved in the form of cellulose as it is, but in order to return to cellulose because it is dissolved as a certain cellulose derivative,
It requires a process called regeneration in addition to coagulation. It has been known that the control of the regeneration process is an important factor that determines the fiber properties of the fiber. The dope modification and coagulation conditions (coagulation bath composition, coagulation temperature, coagulation bath length, bath flow, nozzle, ), Etc., coagulation / regeneration conditions that provide optimum yarn physical properties have been studied from various angles. For example, the viscose rayon method uses a Mueller bath, the polynosic method, H
Examples thereof include a W modulus method, a strong rayon method, and a Lilyenfeld method using a high-concentration sulfuric acid for a coagulation bath, and a falling copper spinning method includes a falling tension spinning method. Both of the above methods cannot avoid the generation of toxic gas and the emission of heavy metals in the process of preparing solutions and in the process of manufacturing molded products, and there is no problem from the viewpoint of work environment and global environment. I can't say. In addition, as a method for dissolving cellulose, cadoxene (cadmium / ethylenediamine / alkaline), nioxene (nickel / ethylenediamine / alkali),
Although metal complexes such as EWNN (iron / tartaric acid / alkari) have been mainly studied, they do not surpass the copper cheap method or viscose method in terms of safety and economy. On the other hand, the viscose method using carbon disulfide is overwhelmingly adopted by many companies in the present regenerated cellulose fiber industry. Waking up. A remarkable manifestation is the withdrawal of many companies from the viscose rayon business in the 1960s and 1970s (first wave), and with the growing anti-environmental destruction movement that is currently being pushed on a global scale. It is urgent for companies to create an environment / safety-oriented system (second wave). In the former case, as a reflection on the existing dissolution method, a study to dissolve cellulose directly in an organic solvent and close the fiber and film manufacturing process to obtain a new regenerated cellulose molded product has been conducted since the 1970s in Canada. , Mainly in the United States. As a result, many dissolution methods were found, but all of them used complicated multi-component solvents and were practically used (industrialized) due to the high cost of the solvent itself, toxicity, explosive properties, and difficulty in solvent recovery. At present, there is no such example. Almost all of these newly discovered dissolving methods use techniques such as the viscose method and the copper copper method in that cellulose is formed into a certain derivative and the derivative is dissolved in an appropriate solvent. There is no significant difference.

[0003] On the other hand, a few attempts have been made to produce a cellulose molded article in an environmentally friendly process for these flows. JP-A-62-240328 and JP-A-62-240329 disclose a method for producing a molded product such as a film or a fiber from a dope obtained by dissolving cellulose in an aqueous alkali solution. According to these, a solid structure of a molded article obtained by selecting a coagulant, particularly one in which the intramolecular hydrogen bonding property has been significantly changed has been obtained. For example, in Japanese Patent Application Laid-Open No. 62-240328, coagulation using an acid directly, or coagulation in advance with water, a base, a neutral salt, or the like, and then neutralization in an acidic bath can destroy intramolecular hydrogen bonds.尺度 am (C, a measure of the degree
In contrast to the method described in JP-A-62-240329, a cellulose molded product having 3% or less of 55% or less is directly coagulated in an acid bath containing a salt, whereby Δam (C3) is 55 to 8%.
It is said that a 5% cellulose molded product can be obtained. Here, χam (C3) is a solid-state high-resolution NMR (CP / MAS
Method), which is the degree of breaking of intramolecular hydrogen bonds, which can be evaluated by the method described in JP-A-62-116601.

The coagulant used in the method described in JP-A-62-240328 is an acidic bath. The use of an acid directly in the first bath is similar to the method of the present invention, but the molded product obtained has a Δam (C3) of only 55% or less due to the low dehydration effect of the acidic bath. Also, Japanese Patent Application Laid-Open No. 62-2403
Similarly, in the case of the method described in No. 229, the dehydration effect of the acidic bath is not sufficient, so that the NMR-like solid structure (χam (C
3)) belongs to the same category as the molded article of the present invention, but there is a difference in the higher-order structure (agglomerated structure) as described later in the Examples, and the physical properties of the obtained cellulose molded article are different. In any case, the wet method suggests that the choice of coagulant controls the physical properties of the molded article obtained. In addition, the present inventors studied various methods for producing a cellulose molded product from the dope composed of cellulose and alkali by using alkali or water, which had low spinnability and was difficult with a normal spinning method, as a coagulant. Even when used, a cellulose molded article has been successfully obtained by forcibly flowing such a coagulation bath (Japanese Patent Laid-Open No. 40806/1991).

However, when producing a molded cellulose product by these methods, a dope consisting essentially of cellulose and alkali is basically used. However, there is no so-called regeneration process, which is an important element for controlling various physical properties. Therefore, in these systems, which were characterized by no regeneration process (chemical reaction), the neutralization process was immediate solidification or gelation, and the coagulation structure during coagulation was controlled, for example, the polymer was coagulated densely during coagulation. It is extremely difficult to control the formation of the solidified gel or to deform the solidified gel, and the physical properties of the obtained molded cellulose product are not sufficiently satisfactory.

[0006]

As described above, the viscose method and the copper copper method are historically classical production methods, but they still play a fundamental role in the textile industry. Absent. However, given the current status of environmental issues on an international scale, it must be said that the industry has many problems. That is: carbon disulfide or ammonia, which has an adverse effect on the human body, is used and has an explosive limit. : It contains copper which is a heavy metal, and harmful waste gas is generated in the process of dissolution / solidification / regeneration / smelting, so that a large amount of energy and water are required for their recovery / purification / disposal processing. :
And, more inevitably, a labor-intensive business form. And the like.

On the other hand, in the case of organic solvent spinning of cellulose,
Although there is an advantage of not using heavy metals or volatile gases, most of them involve a chemical reaction during dissolution, so that cellulose is dissolved in the form of a derivative in the dissolved state, and by-products are generated during regeneration (solvent itself). Of the cellulose derivative), or cannot be regenerated, and finally becomes a molded product with the cellulose derivative as it is. : There is also a problem in terms of solvent recovery, such as loss due to denaturation due to reaction / regeneration of the solvent itself and high cost, which requires a high recovery rate, and a large amount of high boiling point solvents, which requires a great deal of energy. : Of course, there are also problems such as toxicity, decomposability and explosiveness of the solvent itself. It is hard to say that it is industrial from such a viewpoint.

On the other hand, in the prior art relating to a method for producing a molded product such as a film or a fiber from a dope obtained by dissolving cellulose in an alkaline aqueous solution, control of the coagulation structure at the time of coagulation (eg, coagulation at the time of coagulation or coagulation gel) is carried out. Is extremely difficult, and the physical properties of the obtained cellulose molded product are not sufficiently satisfactory. In view of the above, the present inventors systematically examined the coagulability of a dope obtained by substantially dissolving cellulose in an alkaline aqueous solution, from the viewpoint of producing a cellulose molded product by an environmentally friendly process. As a result, it was surprisingly found that if a medium having a high dehydration effect is used as the coagulant, the coagulated structure and the solid structure during coagulation can be easily controlled. That is, in the case of the system of the present invention using a dope consisting essentially of cellulose and alkali, it was an important factor for controlling various physical properties in the molding process of the conventional method (viscose method or copper-aluminum method). The use of a highly dehydrating medium as a coagulant, despite the absence of a regeneration process, facilitates desolvation without causing immediate coagulation or gelation during the neutralization process. Successful and reached the present invention.

An object of the present invention is to provide a process for producing a novel cellulose molded article which does not generate waste gas or explosion during the spinning process and which is free from environmental pollution due to waste liquid and waste gas. It is an object. That is, an object of the present invention is to construct a method for producing a next-generation cellulose molded product that is sufficiently satisfactory from an industrial viewpoint and an environmental problem viewpoint.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a cellulose which is substantially soluble in alkali , or a cellulose having a degree of substitution of 0.2 or less.
In producing a cellulose molded product by a wet method from a dope obtained by dissolving a cellulose derivative in an aqueous alkali solution, the dope is mixed with 50 to 80% by weight of sulfuric acid, 40 to 42.
5% by weight hydrochloric acid, 60-80% by weight nitric acid, 60-90%
By weight polyphosphoric acid, 100% by weight trifluorovinegar
Acid and a mixture of 65% by weight sulfuric acid and 20% metaphosphoric acid
A method for producing a molded cellulose product, comprising coagulating and molding in a solution comprising at least one selected from the group consisting of a combined solution in a temperature range of -8 ° C to 10 ° C.

The cellulose which can be used in the method of the present invention is a so-called alkali-soluble cellulose which can be dissolved in an aqueous alkali solution at a low temperature.
Cellulose disclosed in No. 1 and JP-A No. 62-116601 are preferably used. Further, an alkali-soluble cellulose derivative having a substitution degree of 0.2 or less can also be used. The type of the substituent can be used irrespective of the ether group and the ester group if the degree of substitution is 0.2 or less,
When the degree of substitution is greater than 0.2, the properties of the resulting cellulose molded article are reflected in the properties of the substituent, which is not preferable in physical properties (for example, mechanical properties). In particular,
Methyl, ethyl, alkyl cellulose such as propyl, hydroxyethyl, hydroxyalkyl cellulose such as hydroxypropyl, carboxyethyl cellulose, carbamoylethyl cellulose, cyanoethyl cellulose,
Oxycellulose, cellulose nitrate and the like are used.

The degree of polymerization of cellulose is preferably at least 100 in consideration of the physical properties of the molded article obtained and the operability during molding. On the other hand, the concentration of cellulose is a matter to be determined depending on the degree of polymerization of cellulose and the composition of the solvent. However, it is preferable that the content of cellulose is 3% by weight or more from the viewpoint of economy and physical properties of the obtained molded article. Sodium hydroxide, lithium hydroxide and the like are suitably used as the alkaline aqueous solution as a solvent. In this case, the concentration of the alkali hydroxide is 5 to 15%, and the preferred concentration varies depending on the type. In the case of sodium hydroxide, 7 to 10% by weight is suitably used. The dissolution is performed at a temperature of 16 ° C. or less, preferably from −10 ° C. to 10 ° C. Also, if necessary, a third component, for example, titanium oxide for dull tone, a surfactant for adjusting spinnability,
A crosslinking agent for imparting a function, an alkali-soluble polymer, or the like may be added.

An alkaline solution of cellulose (hereinafter simply referred to as a dope) obtained by the above method is used for sulfuric anhydride, sulfuric acid, halogenated sulfuric acid, thiosulfuric acid, sulfurous acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, nitric acid, A highly dehydrating medium selected from at least one of phosphoric acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, hypophosphorous acid, trifluoroacetic acid, thiocyanate, metal halide salt and the like is used as a coagulant. Molded by use. Here, having a high dehydrating action means that the action of extracting water in the dope into the medium is high. For example, in the case of sulfuric acid, sulfuric acid having a concentration of osmotic pressure π of 390 atm or more is used. Therefore, upon use, these media
It is used in an aqueous solution having a relatively high concentration, that is, in a concentration range having a dehydrating effect on water or an aqueous alkaline solution. Since the concentration range varies depending on the medium used, it cannot be specified unambiguously.
80 to 80% by weight (π: 395 to 1620 atm), and in the case of hydrochloric acid, 40 to 42.5% by weight (π: 1355 to 1619).
atm), in the case of nitric acid, 60 to 80% by weight (π: 133
0 to 6070 atm), and in the case of polyphosphoric acid, 60 to 90
A weight percent range is preferably used. Here, the osmotic pressure π of hydrochloric acid and nitric acid is a value calculated as a regular solution (Raul's law is satisfied) even in a high concentration region. Although such an acid shows a high osmotic pressure π even at the above-mentioned concentration, it is not practical in terms of decomposition, dissolving, denaturing, and handling properties (high smoke emission and high viscosity) for cellulose. When these media are used as a mixture, the concentration of one component may be lower than the above-mentioned concentration. Similarly, the coagulant of the present invention can provide the effects described below even when used in a secondary coagulation bath after using another coagulant in the primary coagulation bath. On the other hand, the temperature of the coagulation bath at the time of molding does not need to be particularly limited, but the lower the temperature at which gelation of the dope does not occur, the more preferable. Particularly preferably, it is −8 ° C. to 10 ° C. -8 ° C not yet
If the temperature is full , the solvent in the dope freezes, which is not preferable. If the temperature exceeds 10 ° C. , the main chain of the cellulose molecule is cut (depolymerized) by the hydrolysis action of the medium, or the dope itself gels. Not preferred.

According to the method of the present invention, there is no particular restriction on the molding method, and it is sufficient to carry out ordinary film forming methods and spinning methods. For example, in the film forming method, a stock solution for film forming is cast on a support plate such as a glass plate using an applicator or a knife coater, and then immersed / coagulated (arbitrary temperature and time) in the medium having the dehydrating action. Thereafter, washing / drying may be performed.

Of course, the liquid may be directly discharged into the coagulation bath using a slit nozzle. In the fiberization, the spinning stock solution is discharged into a coagulation bath using a wet nozzle having a normal pore, a nozzle for hollow fiber, or a jet nozzle, and then, if necessary, is stretched, washed with water, dried, and wound. Just take it. In the case of powdering, the stock solution may be dropped into a coagulation bath under high-speed stirring to form a powder.

[0016]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0017]

Examples 1 to 3 and Comparative Examples 1 to 3 100 parts of softwood pulp (Alaska pulp) having a polymerization degree of 1300 were immersed in 1,000 parts of water for 3 hours, and the water was dehydrated with a dehydrator to remove 190 parts of hydrous cellulose. Obtained. This hydrous cellulose was subjected to a steam treatment at 235 ° C. for 25 seconds using an explosion treatment apparatus (manufactured by Nippon Kagaku Kikai) to obtain cellulose soluble in an aqueous alkali solution having a polymerization degree of 340. 100 g of this cellulose was dissolved in 1900 g of an 8% by weight aqueous solution of caustic soda at 5 ° C. using a homogenizer to obtain a uniform solution. Such a solution is
After filtration using two mesh metal nets and two polyamide non-woven fabrics, the mixture was defoamed by standing naturally to obtain a spinning stock solution.
Using an extruder equipped with a gear pump,
A nozzle having 100 holes of 0.08 mmφ was discharged into a sulfuric acid bath having the concentration shown in Table 1 at a discharge rate of 30.16 ml / min. The coagulation bath was coagulated at a temperature of −5 ° C. and a dipping length of 25 cm, then dried on a hot roll at 120 ° C. through a washing step, and wound around a paper tube at 60 m / min.
Table 1 shows Examples 1 to 3 and Comparative Examples 1 to 3. TS, T
E, KS, and Xc are tensile strength, tensile elongation, knot strength, and X-ray crystallinity, respectively. When 20% and 40% sulfuric acid is used, TS and T are good although spinnability is good.
Since the physical properties of E, KS, etc. are low, the utility as a fiber is low. When 90% sulfuric acid was used, dissolution and decomposition of cellulose in the dope occurred, and spinning was impossible. on the other hand,
In the case of the method of the present invention, Examples 1 to 3, TS, TE, KS, X
Both of them are comparable to existing regenerated cellulose fibers, and can be sufficiently used as clothing fibers.

As described above, according to the method of the present invention, a fiber having the same physical properties as existing ones can be obtained from an extremely simple dope composed of cellulose, alkali and water by a process without environmental pollution.

[0019]

Examples 4 to 8 and Comparative Examples 4 to 6 100 g of an alkali-soluble cellulose prepared according to the method of Example 1 was charged to 5.6.
A homogenizer was dissolved in 1900 g of a 1% by weight aqueous solution of lithium hydroxide at −5 ° C. to obtain a uniform solution. The solution was filtered using three 300-mesh metal nets, and then defoamed by standing naturally to obtain a stock solution. This film forming stock solution was cast on a glass plate using an applicator having a casting thickness of 1 mm, immersed in a coagulation bath shown in Table 2 for 5 minutes, and then sufficiently washed with cold water at 5 ° C. A part of the raw film after washing with water (wet film) was frozen with liquid nitrogen and dried with a freeze dryer. The cross-sectional structure of this dried film was observed using an electron microscope, and the coarseness of the aggregated state was evaluated.
The remaining film was sandwiched between filter papers and vacuum dried, and then used for measuring the elongation. The results are summarized in Table 2. The determination of the aggregated structure (cross-section) was made with the naked eye based on the presence or absence of a void, its size, etc., based on the density of the aggregated state observed with an electron microscope. ○ represents a dense structure having a void diameter of 50 nm or less, and x represents a coarse structure having a void diameter of 200 nm or more. The elongation was measured using a tensile tester "Tensilon" manufactured by Toyo Baldwin.

In Table 2, Examples 4 to 8 and Comparative Examples 4 to 6
Is shown. Example 8 and Comparative Examples 4 and 5 show the effect of the coagulation bath temperature. As is clear from the table, it is shown that the cohesive structure and strength of the obtained film do not increase even if the solidification temperature is low or high. In the case of Comparative Example 4, gelling and freezing of the dope occurred because the solidification temperature was lower than the freezing temperature of the dope,
In the case of Comparative Example 5, it is presumed that the film was inferior due to gelation of the dope and decomposition of cellulose itself. In Comparative Example 6, the degree of breaking of intramolecular hydrogen bonds was large as in the film obtained by the method of the present invention (Δa
m (C3) = 73%), but the aggregate structure and strength are inferior to those of the present invention.

This composition of the coagulation bath substantially corresponds to the Mueller bath composition used in the current viscose rayon method. On the other hand, as can be seen in Examples 4 to 8, according to the method of the present invention, a cellulose film having a strength comparable to that of a commercially available cellophane (viscose method) emits toxic gases such as carbon disulfide and hydrogen sulfide. It can be made from a process without.

[0022]

Examples 9-11, Comparative Examples 7-8 Acid hydrolysis of high α-cellulose pulp (manufactured by Leonia, α-cellulose content 95.4%) using 2.5N sulfuric acid aqueous solution at 50 ° C. for 60 minutes. Then, a cellulose having a viscosity average degree of polymerization of 340 was obtained.
Using this cellulose as a starting material,
The alkali-soluble low-substituted cellulose derivative of No. 3 was prepared to produce a cellulose molded product. (1) Preparation of methylcellulose (MC): 48.6 g of the cellulose prepared by the above method was dissolved in 923.4 g of a 9% by weight aqueous sodium hydroxide solution at 5 ° C., and 7.56 g of dimethyl sulfate (0.2 mol of cellulose) and After adding / mixing 30.2 g of dimethyl sulfate (based on 0.8 mol of cellulose), the mixture was heated to 50 ° C. and reacted for 60 minutes. These dopes were reprecipitated in ethanol, washed several times with ethanol / 2% by weight acetic acid (1/1, vol / vol), and then sufficiently washed with water. Subsequently, it was replaced with acetone and dried under vacuum. The obtained derivative was dissolved in an 8.65% by weight aqueous sodium hydroxide solution, and the degree of substitution was evaluated by NMR measurement. As a result, the degree of substitution was 0.08 and 0.41. (2) Preparation of hydroxypropylcellulose (HPC): 48.6 g of the cellulose prepared by the above method was added to 1
After being immersed in 600 g of a 7.5% by weight aqueous solution of caustic soda at 30 ° C. for 30 minutes, it was pressed to obtain 135 g of alkali cellulose. This alkali cellulose was placed in a sealed container having a deaeration port, deaerated by a vacuum pump, and then 2.6 g of propylene oxide (0.12 mol of cellulose).
l) was injected and reacted at 40 ° C. for 2 hours. The mixture was reprecipitated in ethanol and washed several times with ethanol / 2% by weight acetic acid (1/1, vol / vol).
Washed thoroughly with water. Subsequently, it was replaced with acetone and dried under vacuum.
Similarly, 17.0 g of propylene oxide as a reactant was used.
(To 0.8 mol of cellulose) The injection was also prepared. The obtained derivative was dissolved in an 8.65% by weight aqueous sodium hydroxide solution, and the degree of substitution was evaluated by NMR measurement. As a result, the degree of substitution was 0.06 and 0.38. (3) Preparation of carbamoylethylcarboxyethylcellulose (CEC): Cellulose 4 prepared by the above method
8.6 g was dissolved in 923.4 g of 9% by weight aqueous sodium hydroxide solution at 5 ° C., and 4.32 g of acrylamide (based on 0.2 mol of cellulose) was added / mixed, then heated to 50 ° C. and reacted for 60 minutes. . This dope was reprecipitated in ethanol, and several times ethanol / 2% by weight acetic acid (1/1, vo
(l / vol), and then sufficiently washed with water. Subsequently, it was replaced with acetone and dried under vacuum. The obtained derivative was dissolved in an 8.65% by weight aqueous solution of sodium hydroxide to prepare NM.
As a result of evaluating the degree of substitution by R measurement, the degree of substitution was 0.13.

Each cellulose derivative (42 g) was placed at 5 ° C.
The mixture was dissolved in 558 g of a 9.5% by weight aqueous sodium hydroxide solution using a homogenizer to obtain a uniform solution. This solution was filtered using one 400-mesh metal net and two polyamide non-woven fabrics, and then defoamed by standing naturally to obtain a spinning solution. Using an extruder equipped with a gear pump, this spinning stock solution was discharged from a nozzle having 22 holes of 0.08 mmΦ into a 65% by weight sulfuric acid bath at a discharge rate of 2.2 ml /
min. Coagulation bath temperature is -7 ° C and immersion length 3
After solidification under the condition of 0 cm, the water was washed and the temperature was reduced to 120 ° C.
And heated on a paper tube at 20 m / min.

Table 3 summarizes the physical properties of the obtained fibers. According to the method of the present invention, not only pure cellulose but also a low-substituted cellulose derivative exhibiting alkali solubility can be used to obtain a yarn having the same physical properties as existing regenerated cellulose fibers. When a cellulose derivative having a substitution degree in the above range (Comparative Examples 7 and 8) is used, it is not practical because the wet tensile strength (TSw) is low and the washing resistance is poor.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

According to the present invention, in producing a cellulose molded article having good physical properties from a dope substantially composed of cellulose, alkali and water, there is a danger of generation of waste gas and explosion during the molding process. There is an advantage that a process can be provided that does not cause environmental pollution due to wastewater, waste gas, and the like. In addition, in terms of physical properties, it was substantially the same as existing fibers and films which were not possible in the prior art, which had been attempted to obtain a cellulose molded product having good physical properties from a dope substantially consisting of cellulose, alkali and water. While having mechanical properties, a structure in which intramolecular hydrogen bonds are extremely broken can be formed. Due to such a structural feature, in the case of a fiber, a fiber having excellent resin processability and dyeability can be obtained. In the case of a film, a film having high flexibility can be obtained.

Claims (1)

(57) [Claims] 1. A cellulose substantially soluble in alkali ,
Alternatively , when a cellulose molded product is produced by a wet method from a dope obtained by dissolving a cellulose derivative having a substitution degree of 0.2 or less in an aqueous alkali solution, the dope is used in an amount of 50 to 80 times
% Sulfuric acid, 40-42.5% by weight hydrochloric acid, 60-80%
Wt% nitric acid, 60-90 wt% polyphosphoric acid, 100
Weight percent trifluoroacetic acid, and 65 weight percent sulfuric acid
20% metaphosphoric acid mixed solution selected from the group
Temperature range of -8 ° C to 10 ° C in both solutions
A method for producing a molded cellulose product, characterized by coagulating and molding by the above method.