JP2001316936A - Method for producing solvent spun cellulose fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a solvent cellulose fiber, by which the solvent cellulose fiber can be produced without causing the generation of a whirlpool due to an unstable flow in a spinneret even on high extrusion and without unstabilizing the extrusion. SOLUTION: This method for producing the solvent spun cellulose fiber is characterized by spinning a tertiary amine oxide solution of the cellulose by the use of a spinneret 1 having two or more taper introduction angles, an L/D of <5 [L: the length (7) of a capillary portion; D: a hole diameter (8)], the larger taper angle α near to a flow exit than an angle β and the angle αof <=30 deg..

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 cellulose raw material into a solution with a solvent such as tertiary amine oxide into a solution, and to a method for producing a cellulose fiber solvent.

[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 one type of tertiary amine oxide and an organic solvent. A method for producing cellulose fibers using cellulose as a solvent with NMMO hydrate is disclosed in Japanese Examined Patent Publication No. 28848/1985, and has attracted much attention in recent years because of its light environmental load and excellent physical properties. Japanese Patent Application Laid-Open No. 4-308220 discloses that when spinning is performed using this solution, it is possible to obtain a fine yarn with a low draft ratio from a spinneret having a small pore diameter. However, when a spinneret having a small hole diameter is used, a melt fracture that is unstable in ejection occurs due to a vortex (10 in FIG. 2) generated due to the unstable flow inside the spinneret, and the hole diameter D is 0.2 mm. This is particularly likely to occur in the following cases. When ejection instability occurs, winding at a high spinning speed becomes difficult. This phenomenon becomes more remarkable at the time of high ejection, and it becomes difficult to wind the yarn at a high speed.

[0003] In order to control the occurrence of melt fracture, the diameter D of the hole may be increased. However, the hole diameter D
When the spinning speed is increased, the ejection linear velocity decreases and the draft ratio increases. The smaller the hole diameter of the spinneret, the higher the discharge linear speed and the lower the draft ratio, and it is possible and effective to take up at a high spinning speed.On the other hand, high discharge is affected by the unstable flow inside the spinneret. Melt fracture occurs due to the generated vortex, and winding at a high spinning speed is difficult.

A spinneret having a small hole diameter D and capable of high discharge without generating melt fracture is disclosed in International Patent Publication WO 97/41284. By providing two stages of taper introduction angles, generation of vortices due to unstable flow near the outlet is suppressed, and high discharge is possible. However, in the case of industrial production, the discharge amount is still insufficient and high production is difficult. Also, the taper angle α near the outlet is smaller than the angle β, but in this case, vortices due to instability of flow are more likely to be generated than when the taper angle α near the outlet is larger than the angle β, which is not preferable. . Japanese Patent Application Laid-Open Nos. 10-158922 and 10-158924 disclose a spinneret capable of performing high ejection by minimizing the taper introduction angle. However, when the hole diameter D is 0.25 mm or less, even when the taper introduction angle is reduced, a vortex is likely to be generated due to unstable flow near the outlet, and high discharge is practically impossible.

[0005]

Therefore, according to the present invention, even at the time of high discharge, vortices due to unstable flow inside the spinneret do not occur, and higher discharge is possible than in the prior art. It is an object of the present invention to propose a method for producing a solvent cellulose fiber that can be wound up.

[0006]

That is, the present invention is as follows. 1. Using a spinneret having two or more taper introduction angles, L / D smaller than 5, a taper angle α close to the outlet, larger than angle β, and an angle α of 30 ° or less. A method for producing a solvent-spun cellulose fiber, comprising spinning a tertiary amine oxide solution of cellulose.

[0007] 2. 2. The method for producing a solvent-spun cellulose fiber according to the above item 1, wherein the spinneret is provided with electroless metal plating inside the spinneret.

[0008] 3. 2. The method for producing a solvent-spun cellulose fiber according to the above item 1, wherein the fiber having a hole in which the spinneret is arranged and having a cross section of an irregular or hollow shape can be spun.

4. 2. The method for producing a solvent-spun cellulose fiber according to the above 1, wherein the angle β of the spinneret is from 3 ° to 15 °.

[0010] 5. The hole diameter D of the spinneret is 0.1 mm
3. The method for producing a solvent-spun cellulose fiber according to the above 1, wherein the diameter D1 at the boundary where the taper angle is switched is 0.7 mm or less.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First,
FIG. 1 which is a cross-sectional view of a spinneret used in the present invention will be described. The inflow port of the capillary portion having the length L and the diameter D is provided with two or more taper angles. The taper angle becomes smaller in the direction away from the outlet, and the taper angle α closer to the outlet is larger than the angle β. The diameter at the boundary where the taper angle switches is defined as D1, and the smaller D1 is, the less vortex generated due to the influence of the unstable flow is, and the higher the discharge rate is. Thus, D1 is preferably 0.7 mm or less.

Vortices generated due to unstable flow inside the spinneret can be eliminated by reducing the taper angle at the inlet, and the taper angle α at the inlet near the outlet is from 5 ° to 30 °. ° is preferred. However, making the taper angle of the introduction part extremely small,
It becomes very difficult to machine the inside of the spinneret, and it is difficult to perform sufficient processing. If sufficient processing cannot be performed, ejection may become unstable. In particular, when the taper angle α of the capillary introduction portion is 10 ° or less, it is extremely difficult to perform machining with high accuracy and the production cost increases. Therefore, the taper angle α of the introduction portion is more preferably in the range of 10 ° to 25 °.

[0013] If the taper angle of the introduction portion is provided in two stages, or more than three stages, a vortex generated due to flow instability at the entrance of the introduction portion is less likely to occur, and the taper angle of the introduction portion is one stage. This is preferable because high discharge can be achieved as compared with the case. In addition, the vortex generated due to unstable flow inside the spinneret has a taper angle α of the capillary introduction part,
When the angle is larger than the taper angle β, it hardly occurs and it is desirable. The smaller the introduced taper angle β is, like α, the smaller the vortex generated due to unstable flow inside the spinneret is preferably generated. The taper angle β is preferably in the range of 5 ° to 15 °.

A spinneret having two stages of taper angles of the introduction portion is disclosed in International Publication WO97 / 41284. The taper angle of the introduction portion is shown in FIG. Is smaller than β in FIG. When the introduction angle β is the same as the introduction angle α, a vortex generated due to unstable flow inside the spinneret shown in FIG. 2 is more likely to be generated than when the introduction angle β and the introduction angle α are different. When the relationship between the taper angles α and β and the ejection stability of the introduction portion was examined, it was found that a larger ejection angle was possible when the angle α was larger than the angle β than when it was smaller. It has been found that the taper angle α of the introduction portion is preferably larger than the angle β. In addition, the larger the taper angle α, the more accurate the processing can be performed, and the vortex generated due to the unstable flow caused by insufficient processing can be suppressed. Therefore, the taper angle β is desirably smaller than the taper angle α.

At the same time, when the diameter D1 at the boundary where the taper angle is switched is made as small as possible, the generation space of the vortex due to instability of the flow generated near the switching of the taper angle can be narrowed, and high discharge can be achieved. D1 is preferably 0.7 mm or less.

Japanese Patent Application Laid-Open No. 7-3523 discloses that it is effective to increase the L / D in order to enhance the flow stability of the spinning solution in the spinneret. However, the lengthening of L / D and the vortex generated due to flow instability were irrelevant. Further, if L / D is lengthened, processing cost increases, which is not preferable. It is preferable to use a spinneret having an L / D of less than 5, more preferably an L / D of 3
These are:

Further, by subjecting the inside of the spinneret to electroless metal plating with low wettability, the flow resistance generated on the wall surface can be reduced. For this reason, even when a high shear rate is applied, that is, at the time of high discharge, the flow stability is enhanced, and discharge is less likely to be unstable. Nickel, copper, tin, and aluminum are preferred as the metal for plating.

The hole shape of the spinneret is not limited to a round shape. By overlapping the holes, the present invention can be applied to a spinneret for producing fibers of irregular cross-section such as a multi-leaf or a cross as shown in FIG. 3 and a spinneret for producing hollow fiber.

Hereinafter, the method for producing a solvent-spun cellulose fiber according to the present invention will be specifically described.

The present invention uses any of the spinnerets described above to produce solvent cellulose fibers. It is preferable to use wood refined pulp having a cellulose average polymerization degree of about 800 as a raw material. The solution can be adjusted even when cellulose having a high degree of polymerization and cellulose having a low degree of polymerization are mixed. When cellulose is dissolved in NMMO hydrate, the temperature during dissolution is preferably 90 to 135 ° C.
Further, when the cellulose concentration is adjusted to 5 to 35 wt%, uniform dissolution is possible, and preferably 10 to 20 wt%. In dissolving the cellulose, 0.1% of an antioxidant is used for the purpose of preventing a decrease in the degree of polymerization of cellulose and decomposition of NMMO.
It is desirable to add ~ 2.0 wt%. The adjusted spinning dope is sent to a spinning head, measured by a gear pump, and supplied to a spin pack. The temperature is preferably from 90 to 135 ° C. If the temperature is lower than 90 ° C., the viscosity of the spinning stock solution is high, and it is practically difficult to discharge. It is effective to perform filtration in order to remove foreign substances in the spinning solution, and it is desirable to use a sand during spin pack or to perform filtration with a mesh metal filter or the like.

The spinning solution discharged from the spinneret is stretched between the spinneret and the surface of the coagulating liquid (air gap). The air gap may be set to about 10 mm to 100 mm, and at the time of high spinning speed, it is preferable to adopt a method of actively cooling the discharged yarn using a quench chamber or the like. As the coagulation bath, an aqueous solution of NMMO is preferably used, and the coagulation bath temperature is preferably about room temperature. The yarn that has passed through the coagulation bath is subsequently washed with water and dried, and then wound up as a yarn by a winder.

If the cellulose concentration of the spinning dope and the cellulose pulp used as a raw material differ in the cellulose average polymerization degree, the melt viscosity of the spinning dope differs, so that the viscosity increases as the cellulose concentration and the cellulose average polymerization degree increase. Discharge instability tends to occur. When the spinning temperature is 10
When the temperature is 0 ° C. or lower, ejection instability is likely to occur, and the temperature is preferably 100 ° C. or higher, and more preferably 110 ° C. The pore diameter D is set at 0.
When the thickness is 1 mm or less, ejection instability is likely to occur, and it is difficult to perform sufficient ejection.

[0023]

The present invention is not limited to the following embodiments, but the present invention is not limited to these embodiments. The composition of the spinning dope and the average degree of cellulose polymerization were confirmed by the methods described below.

<Method of Evaluating Degree of Cellulose Polymerization> The degree of polymerization of cellulose was measured by the cubic ethylenediamine method. A sample is weighed in an amount of 0.0075 to 0.0085 g and put into a Cucumber / ethylenediamine solution. The mixture was stirred at room temperature for about 30 minutes to completely dissolve the sample.
The measurement was performed while the temperature was kept constant at 0 ° C.

<Method of Evaluating Dope Composition> The moisture content in the spinning stock solution was measured by a trace moisture analyzer (Model AQ-7, manufactured by Hiranuma Sangyo Co., Ltd.). About 5 g of the test piece was weighed, about 20 ml of absolute ethanol (99.5%) was added, and the mixture was allowed to stand at room temperature overnight, after which measurement was performed. The cellulose concentration in the spinning dope was determined by measuring the weight of the spinning dope and then thoroughly washing the spinning dope with water to precipitate cellulose. And the weight after drying at 60 degreeC all day and night was measured. The cellulose solution was washed well with the weight of the spinning dope to precipitate cellulose, and the cellulose concentration was calculated from the difference in weight after drying at 60 ° C. overnight.

In order to produce a solvent cellulose fiber, a wood refined pulp made by Nippon Paper having an average degree of polymerization of 800 was used as a raw material. When dissolving cellulose in NMMO hydrate manufactured by Nippon Emulsion, raw materials were added by mixing under reduced pressure so that the cellulose concentration became 15 wt%. Also, gallic acid n as an antioxidant
-Propyl was added at 0.25 wt%. Temperature 110 ° C,
By stirring under reduced pressure for about 3 hours, a spinning stock solution was obtained. The adjusted spinning solution was sent to the spinning head, measured by a gear pump, supplied to a spin pack, and discharged using the spinneret of the present invention. The temperature at the time of ejection was kept constant at 110 ° C. In addition, in order to remove foreign substances in the spinning solution, filtration was performed immediately before the spinneret using a mesh metal filter.

The spinning solution discharged from the spinneret is 50 m
m in the air gap. In addition, the discharge yarn was heated at a temperature of 20 ° C. and a wind speed of 0.8 m using a quench chamber.
/ Sec. Coagulation bath is NM at 13 ℃
An aqueous solution having an MO concentration of 18 wt% was used.

As a result of confirming the cellulose concentration and the degree of cellulose polymerization of the adjusted spinning solution, the cellulose concentration was 1%.
It was 5.3 wt% and the degree of cellulose polymerization was 489.

Example 1 Using the above spinning stock solution,
= 0.2 mm, D1 = 1.0 mm, L / D = 1, α = 2
A spinneret having 0 °, β = 10 °, and 20 holes was heated at a temperature of 11 °.
The temperature was kept at 0 ° C., and the discharge amount at the limit where flow instability occurred was measured. As a result, discharge at 9.8 g / min was possible. When spinning was performed at a spinning speed of 400 m / min, thread breakage occurred once / day, but the spinning state was stable.

Example 2 Using the above spinning dope, D
= 0.2 mm, D1 = 0.5 mm, L / D = 1, α = 2
A spinneret with 0 °, β = 10 °, and 20 holes arranged in a cruciform shape was held at a temperature of 110 ° C., and a limit discharge amount at which flow instability occurred was measured. Was possible. By making D1 small, high ejection becomes possible. When spinning was performed at a spinning speed of 400 m / min, no yarn breakage occurred and the spinning was stable.

<Example 3> Using the above spinning dope, D
= 0.2 mm, D1 = 0.5 mm, L / D = 1, α = 2
A spinneret having 0 °, β = 10 °, and 20 holes was heated at a temperature of 11 °.
The temperature was kept at 0 ° C., and the limit discharge amount at which flow instability occurred was measured. As a result, discharge at 38.8 g / min was possible.
By making D1 even smaller, higher ejection was possible. When spinning was performed at a spinning speed of 500 m / min, no yarn breakage occurred and the spinning was in a very stable state.

Example 4 Using the above spinning dope, D
= 0.1 mm, D1 = 0.5 mm, L / D = 1, α = 2
A spinneret having 0 °, β = 10 °, and 20 holes was heated at a temperature of 11 °.
The temperature was kept at 0 ° C., and the limit discharge amount at which flow instability occurred was measured. As a result, discharge at 3.0 g / min was possible. When spinning was performed at a spinning speed of 200 m / min, no yarn breakage occurred and spinning was stable.

Example 5 Using the above spinning dope, D
= 0.2 mm, D1 = 0.5 mm, L / D = 1, α = 2
The spinneret with electroless nickel metal plating inside the spinneret at 0 °, β = 10 ° and 20 holes was kept at a temperature of 110 ° C., and the limit discharge amount at which flow instability occurred was measured. Discharge of 2 g / min was possible. By applying electroless nickel metal plating inside the spinneret, a higher discharge was possible. When spinning was performed at a spinning speed of 550 m / min, no yarn breakage occurred and the spinning was very stable.

Example 6 Using the above spinning dope, D
= 0.1 mm, D1 = 0.5 mm, L / D = 1, α = 2
4. The spinneret with electroless nickel metal plating inside the spinneret at 0 °, β = 10 °, and 20 holes was held at a temperature of 110 ° C, and the limit discharge amount at which flow instability occurred was measured. Discharge of 0 g / min was possible. When spinning was performed at a spinning speed of 250 m / min, no yarn breakage occurred and spinning was stable.

<Comparative Example 1> Using the above spinning stock solution,
= 0.2 mm, L / D = 1, α = 20 °, β = 0 °, the number of holes was kept at 110 ° C, and the limit discharge amount at which flow instability occurred was measured. 0.6 g / mi
It was possible to discharge n. When spinning was performed at a spinning speed of 300 m / min, thread breakage occurred frequently and the spinning was very unstable.

<Comparative Example 2> Using the above spinning stock solution,
= 0.2 mm, D1 = 0.5 mm, L / D = 0.1, α
= 10 °, β = 60 °, the number of holes was 20 and the spinneret was maintained at a temperature of 110 ° C, and the limit discharge amount at which flow instability occurred was measured. As a result, discharge at 16.6 g / min was possible. . When spinning was performed at a spinning speed of 400 m / min, thread breakage occurred four times / day and spinning was unstable. Further, when the yarn was spun at a discharge rate of 19.1 g / min, the yarn could not be passed.

<Comparative Example 3> Using the above spinning stock solution,
= 0.1 mm, D1 = 0.5 mm, L / D = 0.1, α
= 10 °, β = 60 °, the number of holes was 20 and the spinneret was maintained at a temperature of 110 ° C, and the limit discharge amount at which flow instability occurred was measured. As a result, 2.6 g / min discharge was possible. . When spinning was performed at a spinning speed of 200 m / min, thread breakage occurred 7 times / day, and spinning was unstable. When spinning was performed at a discharge rate of 3.0 g / min, it was very difficult to pass the yarn.

<Comparative example 4>
= 0.2 mm, L / D = 15, α = 20 °, β = 0 °,
The spinneret having 20 holes was held at a temperature of 110 ° C., and the limit discharge amount at which flow instability occurred was measured.
/ Min was possible. Spinning speed 300m / m
When spinning was performed in, yarn breakage occurred three times / day, and spinning was unstable. When spinning was performed at a discharge rate of 9.8 g / min, the yarn could not be passed.

[0039]

[Table 1]

As shown in Table 1, the taper introduction angle α is an angle larger than β, and Examples 3 and 4 where D1 is small and Comparative Examples 2 and 3 where the taper introduction angle α is an angle smaller than β. Also, it can be understood that the dischargeability and the spinning stability are excellent. In addition, the use of a spinneret that has been subjected to electroless metal plating enables extremely high discharge,
Also at high spinning speed, spinning stability is very good,
It can be understood that it is significantly superior to the comparative example. Also,
It can be understood that high ejection is possible even if L / D is sufficiently small, and that spinning stability is sufficient.

[0041]

According to the manufacturing method using the spinneret according to the present invention, vortices caused by unstable flow inside the spinneret are less likely to occur, and high discharge can be achieved even when the hole diameter D is small, and high spinning speed can be achieved. Also, the productivity can be greatly improved without deteriorating the spinning stability.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of a spinneret for a solvent cellulose fiber used in the present invention.

FIG. 2 is a schematic view of the occurrence of melt fracture in a spinneret.

FIG. 3 is an example of a hole arrangement of a spinneret for a modified section and a spinneret for a hollow.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Spinneret 2 ... Outlet 3 ... Hole diameter at the boundary where the taper angle is switched 4 ... Taper angle near the outlet 5 ... Taper angle far from the outlet 6 ... Inlet hole diameter 7 ... Capillary part length 8 ... Hole diameter 9 ... Melt fracture 10 ... vortex 11 ... stable flow a ... multi-leaf b ... cross-shaped c ... triangular hollow

Claims (5)

[Claims] An L / D having two or more taper introduction angles.
Is smaller than 5, the taper angle α close to the outlet is an angle larger than the angle β, and the angle α is 30 ° or less, using a spinneret to spin a tertiary amine oxide solution of cellulose. A method for producing a solvent-spun cellulose fiber. 2. A method for producing a solvent-spun cellulose fiber according to claim 1, wherein said spinneret is provided with electroless metal plating inside the spinneret. 3. The method for producing a solvent-spun cellulose fiber according to claim 1, wherein said spinneret has holes in which the spinnerets are arranged, and is capable of spinning a fiber having an irregular or hollow cross section. 4. The angle β of the spinneret is from 3 ° or more to 1 °.
The method for producing a solvent-spun cellulose fiber according to claim 1, which is at most 5 °. 5. The production of a solvent-spun cellulose fiber according to claim 1, wherein the diameter D of the spinneret is 0.1 mm or more and 0.3 mm or less, and the diameter D1 at the boundary where the taper angle switches is 0.7 mm or less. Method.