JP2001316938A - Method for producing cellulose formed article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for producing a high quality cellulose formed article, which can industrially be utilized and can also stabilize the quality of the cellulose formed article when recycling a cellulose resource except high quality chemical cellulose. SOLUTION: This method for producing the cellulose formed article is characterized by extruding a cellulose tertiary amine oxide solution containing >=1 wt.% of chemical pulp and kenaf pulp in a controlled shape and then coagulating and solvent-extracting the extrusion product. The method for producing the cellulose formed article further comprises separately dissolving the chemical pulp and the kenaf pulp in the tertiary amine oxide, and then extruding the cellulose solutions from an extrusion nozzle in a conjugate fiber shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a raw material of cellulose into a solution with a solvent such as tertiary amine oxide to form fibers, rods, sheets, membranes and the like.

[0002]

2. Description of the Related Art Instead of the viscose method, cellulose is replaced with N.
A method of molding -methylmorpholine-N-oxide (NMMO) hydrate as a solvent is industrially used,
As a typical example, lyocell fiber is well known. NMMO is a kind of tertiary amine oxide and is an organic solvent, and it is disclosed in International Publication WO96 / 07778 that the use of this solvent can convert used cloth, annual grass, waste paper and the like into fibers. However, it has been difficult to produce a cellulose molded article having a stable quality as compared with a high-purity chemically purified pulp. In particular, there has been a problem that unevenness in the degree of polymerization causes unevenness in mechanical properties and fluid properties of a cellulose solution (hereinafter referred to as a dope for molding) are not stable, so that they are liable to be broken at the time of production. In addition, International Patent Publication WO
No. 98/22642 discloses a technique for fibrillating hemicellulose such as kenaf or cellulose having a high content of lignin. However, if lignin is contained in pulp, undissolved matter may cause a decrease in spinnability or high polymerization. There was a problem that the mechanical properties were not sufficiently high as compared with fibers obtained from highly purified cellulose. In addition, as a raw material for molded articles such as cellulose fibers, cellulose films, and cellulose shells and paper, chemical pulp purified from wood, such as softwood or hardwood, to have an α-cellulose content of 90% or more is industrially used. Has been used in many ways. This chemical pulp has a controlled degree of cellulose polymerization and components, and can be stably produced without breaking even in a molding method having a step of stretching thinly such as a fiber or a film. However, given the recent deforestation,
Effective utilization of non-wood cellulose is desired. From this point of view, kenaf pulp is a remarkable raw material because of its high cellulose production even with low resource input.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a technique for producing a high-quality molded product which is stable in quality even when using cellulose resources other than high-quality chemical cellulose, and is industrially applicable. Is what you do.

[0004]

That is, the present invention provides: 1. A method for producing a cellulose molded article, comprising discharging a cellulose tertiary amine oxide solution containing 1% by weight or more of chemical pulp and kenaf pulp to control the form, followed by coagulation and solvent extraction. 2. The method for producing a cellulose molded article according to the above item 1, wherein each pulp is individually dissolved in a tertiary amine oxide, and each pulp solution is mixed in a molding step. 2. The method for producing a cellulose molded article according to the item 1, wherein each of the pulp solutions is discharged in a composite manner from an extrusion die.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The chemical pulp in the present invention is a pulp subjected to delignification treatment which is generally called a chemical pulp, and examples thereof include sulfite pulp, sulfate pulp, and soda pulp. In the mixing ratio of the chemical pulp and the kenaf pulp in the present invention, the ratio of the chemical pulp is 1% by weight or more.
When the amount of the chemical pulp whose quality is controlled is less than 1%, the effect of improving poor dope moldability in the case of kenaf pulp alone is small.

[0006] In addition, it is possible to produce a cellulose molded product having a stable quality by performing composite molding such as multilayer discharge of each molding dope obtained from each different cellulose pulp. When using a method such as multilayer extrusion,
It is preferable that one component is at least 5% by weight in order to stably coextrude. It is preferable that the degree of polymerization of the chemical pulp to be used is appropriately selected according to the quality of the kenaf pulp to be combined. When the degree of polymerization of kenaf pulp is high,
Combinations that lower the degree of polymerization of chemical pulp are also possible, and if the quality of kenaf pulp is unstable,
It is preferable to increase the mixing ratio of the chemical pulp.

The tertiary amine oxide in the present invention is an organic solvent capable of dissolving cellulose represented by N-methylmorpholine-N-oxide hydrate at a concentration of 10% by weight or more. The tertiary amine oxide solution may contain an antioxidant, a pH adjuster, and a third component for adjusting the fluid properties of the solvent.

In the present invention, a spinneret is used for producing a fiber, a slit die is used for producing a film,
In addition, a tertiary amine oxide solution of cellulose is discharged from a mold gate or the like, and the form of the discharged material is controlled by uniaxial stretching, blow stretching, foam molding, or the like. The present invention is not limited to the above-described example regarding the method of controlling the form of the discharged solution, and it is possible to select a molding method suitable for a desired molded product.

[0009] The solution whose form is controlled is brought into contact with a non-solvent and solidified to fix the form. As the non-solvent used here, water, lower alcohols, ketones such as acetone can be used, but water is preferable when industrially a large amount is used. During and after the coagulation, the solvent in the compact is extracted. For the extraction, non-solvent water or the like can be used, but a supercritical fluid may be used.

The above-mentioned molded product may be used as a porous material containing a non-solvent. However, when it is used as a fiber or a film, a drying step for removing the non-solvent in the molded product is required. Drying can be performed by any method such as hot air heating, air drying at room temperature, and freeze drying. It is also possible to crimp the fiber after drying or before drying, cut and use it, or cut the film into a tape shape and use it as a flat yarn. Before or after the molded article is processed into a knitted or woven fabric, dyeing, kneading, surface treatment or modification treatment can be performed.

In the present invention, two or more kinds of cellulose raw materials can be used. When dissolving cellulose in a tertiary amine oxide solution, the dissolution rate varies depending on the cellulose raw material. Therefore, it is necessary to adjust the pulverization conditions and the dissolution time of the raw material accordingly. Further, it is necessary to change the conditions for filtering the foreign matter in the raw material according to the amount and size of the foreign matter contained. Therefore, it is preferable to separately feed the chemical pulp and the kenaf pulp to the melting facility.

This method is advantageous when the dissolved cellulose dope is mixed with a liquid or when extruded individually to form a composite. That is, it is difficult to uniformly disperse and mix a plurality of types of cellulose in the state of pulverized cellulose, but in the case of liquid, uniform mixing can be achieved by appropriately using a mixing device. As a means for mixing uniformly, in an undissolved or semi-dissolved slurry state or a completely dissolved state, a kneader, a twin-screw extruder, a single-screw extruder having a mixing mechanism, a horizontal or vertical stirring can be used. it can. When mixing in a short time, an apparatus capable of mixing at a high shear rate with a small clearance of the stirrer is preferable. On the other hand, when multiple types of cellulose are extruded individually, individual dissolution is essential.

Although kenaf pulp can be bleached, it has a slightly brownish tint as compared with chemical pulp made of wood. In addition, it is also possible to make it unbleached in consideration of environment and raw material cost. In such a case, unbleached kenaf pulp is placed on the core by composite molding,
Chemical pulp can be arranged on the outer periphery or on the surface, and the design is improved.

As a method of composite molding of different types of cellulose, a known sea-island or side-by-side composite die, a multi-layer slit die, or the like, which is mixed with a static mixer in the middle of piping, can be selected. It is also possible to use a method in which the material is discharged independently from the die and joined before solidification.

As described above, the molded article according to the present invention can be used as a material for clothing, a packaging material, and an industrial material.

[0016]

The present invention will be described below with reference to examples.
The present invention is not limited to these. The measuring method used in the present invention is as follows. <Measurement of Cellulose Degree of Polymerization> The degree of polymerization of cellulose was measured by the Cucumber ethylenediamine method ("Polymer Material Test Method 2" edited by The Society of Polymer Science, page 267, Kyoritsu Shuppan (19)
65)). A sample was weighed in an amount of 0.0075 to 0.0085 g and placed in a Cucumber / ethylenediamine solution.
After stirring at room temperature for about 30 minutes to completely dissolve the sample, the temperature was kept constant at 20 ° C., and the viscosity was measured using an Ubbelohde viscosity tube to determine the degree of polymerization.

<Measurement of moisture content in dope> The moisture content in the dope was measured using a trace moisture analyzer (Model A, manufactured by Hiranuma Sangyo Co., Ltd.).
Q-7). About 1 g of a test piece was weighed, about 10 ml of absolute ethanol (99.5%) was added, and the mixture was allowed to stand at room temperature overnight, after which measurement was performed.

Example 1 Chemical cellulose (pulp) 5
5600 g of NMMO solvent containing 65 g and 50% by weight of water
The mixture was heated to 110 ° C. while stirring and a dope having a cellulose concentration of 15% was prepared by reducing the pressure. The water content in the dope was 10.7%. Furthermore, 550 g of powder obtained by cutting and pulverizing kenaf whole stem kraft pulp and 50
5,000 g of an NMMO solvent containing water by weight was heated to 110 ° C. while stirring, and the pressure was reduced to obtain a cellulose concentration of 16%.
% Dope was adjusted. The moisture content in this dope is 11.
2%. Both of these two types of dopes were candy-colored viscous materials. The individual dopes of chemical cellulose and kenaf pulp were coagulated, precipitated, washed and dried with water, and the degree of polymerization of each cellulose obtained was 600 and 420, respectively.

Each of these dopes was filled in two plunger type supply tanks each having a piston. The dope supplied from these was metered through individual gear pumps such that the weight ratio of chemical cellulose dope to kenaf pulp dope 75 was 25, and a Kenix type of 3.2 mm in diameter, consisting of 18 elements. The mixture was mixed using a static mixer and discharged from a spinneret.

A spinneret having an exit diameter of 10 holes and a diameter of 200 μm was used, and the total dope discharge amount was 6.7 g / d.
Minutes. The temperature of the spinneret was set at 108 ° C, and the yarn was cooled with air adjusted to 15 ° C at a wind speed of 1.2 m / sec immediately below the spinneret. 50mm 300mm below the nozzle
After being brought into contact with water by a coagulation funnel having a diameter of mm, the film was wound on a Nelson roller to which water had been dropped. The speed of the Nelson roller was 450 m / min and the fiber denier after air drying was 23.3 dTex. Table 1 shows the physical properties of the obtained regenerated cellulose fiber. It has comparable mechanical properties as compared to fibers obtained from chemical cellulose.

Comparative Example 1 Only a single dope obtained from the chemical cellulose of Example 1 was filled in a plunger type supply tank equipped with a piston. The supplied dope was metered into a spinneret through a gear pump. A spinneret having 10 holes and an outlet diameter of 200 μm was used, and the total dope discharge amount was 6.7 g / min. Spinneret temperature is 10
The temperature was set to 5 ° C, and the yarn was cooled with air adjusted to 15 ° C at a wind speed of 1.2 m / sec immediately below. After being brought into contact with water using a 50 mm deep coagulation funnel provided 300 mm below the nozzle, it was wound on a Nelson-type roller on which water had been dropped. The speed of the Nelson roller was 450 m / min, and the fiber denier after air drying was 23.1 dTex. Table 1 shows the physical properties of the obtained regenerated cellulose fiber.

Comparative Example 2 Only a single dope obtained from the kenaf whole stalk pulp of Example 1 was filled in a plunger type supply tank equipped with a piston. The supplied dope was metered into a spinneret through a gear pump. A spinneret having 10 holes and an outlet diameter of 200 μm was used, and the total dope discharge rate was 5.2 g / min. Spinneret temperature is 1
The temperature was adjusted to 05 ° C, and the yarn was cooled with air adjusted to 15 ° C at a wind speed of 1.2 m / sec immediately below. 300mm from nozzle
After being brought into contact with water using a 50 mm deep coagulation funnel provided below, it was wound on a Nelson-type roller on which water had been dropped. The speed of the Nelson roller was 350 m / min, and the fiber denier after air drying was 23.0 dTex.
Table 1 shows the physical properties of the obtained regenerated cellulose fiber.

Example 2 604 g of chemical cellulose and 5
While stirring with 5600 g of an NMMO solvent containing 0% by weight of water, the mixture was heated to 110 ° C. and depressurized to perform a cellulose concentration of 1%.
A 6% dope was prepared. The water content in the dope is 9.8%
Met. N containing 529 g of powder obtained by cutting and pulverizing kenaf kraft pulp and 50% by weight of water
5600 g of the MMO solvent was heated to 110 ° C. while stirring, and the pressure was reduced to prepare a dope having a cellulose concentration of 14%. The water content in this dope was 11.9%. Both of these two types of dopes were candy-colored viscous materials. The individual dopes of the chemical cellulose and the kenaf core pulp were coagulated, precipitated, washed and dried with water, and the degree of polymerization of each cellulose obtained was 660 and 320, respectively.

Each of these dopes was filled into two plunger type supply tanks each having a piston. The dopes supplied from these were metered through individual gear pumps into a sea core type spinneret so that the chemical cellulose was sheathed and the kenaf core pulp was in the core. The weight ratio of the ejection amount was 65 for kenaf dope and 3 for sheath component dope.
The ratio was 5. 10 holes sea core type, outlet diameter 2
A spinneret having a diameter of 00 μm was used, and the total dope discharge amount was 6.7 g / min. Spinneret temperature is 108 ℃
The yarn was cooled with air adjusted to 15 ° C. at a wind speed of 1.2 m / sec immediately below. After contact with water with a 50 mm deep coagulation funnel 300 mm below the nozzle,
The film was run on a Nelson roller to which water had been dropped, and wound up. The speed of the Nelson roller was 450 m / min and the fiber denier after air drying was 23.4 dTex. Table 1 shows the physical properties of the obtained regenerated cellulose fiber. It has comparable mechanical properties compared to fibers obtained from chemical cellulose.

Comparative Example 3 Only a single dope obtained from the kenaf core of Example 3 was charged into a plunger type supply tank equipped with a piston. The supplied dope was metered into a spinneret through a gear pump. Outlet diameter 2 with 10 holes
A spinneret having a diameter of 00 μm was used, and the total dope discharge rate was 5.2 g / min. Spinneret temperature is 105 ℃
The yarn was cooled by air adjusted to 15 ° C. at a wind speed of 1.2 m / sec immediately below. After contact with water with a 50 mm deep coagulation funnel 300 mm below the nozzle,
The film was run on a Nelson roller to which water had been dropped, and wound up. The speed of the Nelson roller was 350 m / min, and the fiber denier after air drying was 23.1 dTex. Table 1 shows the physical properties of the obtained regenerated cellulose fiber.

[0026]

[Table 1]

As is clear from Table 1, those satisfying the requirements of the present invention can obtain mechanical strength comparable to that of regenerated cellulose fibers obtained from chemical cellulose alone.

Example 3 463 g and 50 of chemical cellulose
NMMO solvent containing 6000 g of water containing 100% by weight of water was heated to 100 ° C. while stirring, and the pressure was reduced.
A 2% dope was prepared. Moisture content in the dope is 10.3
%Met. Further, 550 g of a powder obtained by cutting and pulverizing unbleached kenaf pulp and 5000 g of an NMMO solvent containing 50% by weight of water were heated to 100 ° C. with stirring, and the pressure was reduced to adjust a dope having a cellulose concentration of 16%. The water content in this dope was 11.2%. The individual dopes of the chemical cellulose and the waste paper were coagulated and precipitated with water, washed and dried, and the polymerization degrees of the respective celluloses were 600 and 380, respectively. Both of these two types of dopes were candy-colored viscous materials.

Each of these dopes was charged into two plunger type supply tanks each having a piston. The dope supplied from these is passed through a separate gear pump to the sheath core type spinneret, and the chemical cellulose dope is sheathed.
The kenaf pulp dope was metered into the core. The weight ratio of the discharge amount was 70 for the core kenaf pulp dope and 30 for the sheath component dope. Using a spinneret having an outlet diameter of 200 μm with a 10-core sea core type,
The total dope discharge amount was 6.7 g / min. The temperature of the spinneret was set at 108 ° C, and the yarn was cooled with air adjusted to 15 ° C at a wind speed of 1.2 m / sec immediately below the spinneret. After being brought into contact with water using a 50 mm deep coagulation funnel provided 300 mm below the nozzle, it was wound on a Nelson-type roller on which water had been dropped. The speed of the Nelson roller is 450 m / min and the fiber denier after air drying is 23.3 dTe.
x. As in this example, it is possible to confine the cellulose component derived from kenaf pulp inside the molded body.

[0030]

According to the present invention, a stable quality cellulose molded article is produced by using pulp derived from kenaf, which is a non-wood material, as a raw material in combination with high quality wood chemical pulp. I can do it.

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Claims (3)

[Claims] 1. A method for producing a cellulose molded article, comprising discharging a cellulose tertiary amine oxide solution containing 1% by weight or more of chemical pulp and kenaf pulp to control the form, followed by coagulation and solvent extraction. 2. The method for producing a cellulose molded article according to claim 1, wherein each pulp is individually dissolved in a tertiary amine oxide, and each pulp solution is mixed in a molding step. 3. The method for producing a cellulose molded article according to claim 1, wherein each of the pulp solutions is compositely discharged from an extrusion die.