KR100611892B1 - Cellulose fiber and its manufacturing process - Google Patents

Abstract

The present invention relates to a method for producing cellulose fibers by N-methyl morpholine-N-oxide (NMMO) / water mixed solvent, having a high degree of polymerization (1,000 ~ 1,600) and high α-cellulose content (95% or more) The cellulose powder and the cellulose powder having a low polymerization degree (400 to 800) and a low α-cellulose content (87% or less) are mixed at a ratio of 90/10 to 50/50% by weight, and then dissolved in a kneader or an extruder to form a spinning nozzle. Extruded through, and the extruded fiber is cooled in an air layer, solidified in a coagulation bath, washed with water, and dried to prepare a method for producing a cellulose fiber.

The present invention optimizes the mixing ratio in the process of dissolving a mixture of high polymerization cellulose and a large amount of low polymerization cellulose in NMMO aqueous solution, thereby eliminating the rheological behavior caused by using high polymerization cellulose and simultaneously preventing fibril resistance. It is characterized by the production of cellulose fibers having excellent physical properties.

High polymerization cellulose, low polymerization cellulose, α-cellulose content, N-methylmorpholine-N-oxide, viscosity, fibril resistance

Description

Cellulose fiber and its manufacturing process {Cellulose fiber and its manufacturing process}

1 is a schematic diagram showing a manufacturing process of cellulose fibers according to the present invention

The present invention relates to a cellulose fiber having excellent physical properties and fibrillation resistance and a method of manufacturing the same.

More specifically, NMMO (N-methylmorpholine-N-oxide) concentrated by distillation under reduced pressure is used to dissolve cellulose having high polymerization degree (DP 1,000 to 1600) and high α-cellulose content (95% or more). At this time, a large amount of low polymerization degree (DP 400 to 800) and low-alpha cellulose content (below 87%) are added and mixed, dissolved in a kneader or an extruder, and then extruded through a nozzle in an extruder to coagulate, wash and It relates to a cellulose fiber produced by drying and a method for producing the same.

In general wet and dry spinning, especially in the wet and dry spinning of regenerated cellulose fibers, all stretching is achieved until the coagulation bath is removed from the nozzle inlet. Particularly in the production of cellulose fibers using NMMO solvent, the final physical properties in spinning and solidification processes It is difficult to improve the physical properties because most of the structure of the affected cellulose is made.

As a method for improving physical properties, a method of dissolving and spinning pulp having a high degree of polymerization and a high content of α-cellulose may be considered, but this method is due to a decrease in solubility due to an increase in the degree of polymerization and α-cellulose content of the pulp. There is a disadvantage in that the concentration must be reduced, and in addition to the difficulty in conveying due to the increase in viscosity of the stock solution, various problems such as raising the pressure in the nozzle pack during spinning are generated.

U.S. Patent Nos. 4,142,913, 4,144,080, 4,196,282, 4,246,221, 4,211,574, and 4,416,698 are prepared by injecting cellulose into NMMO aqueous solution to swell and continue depressurizing water to prepare a uniform cellulose solution. A method for producing a tertiary amine oxide based cellulose fiber is prepared by dissolving cellulose to remove fibers while removing it.

Cellulose fibers prepared by the above method have many advantages, such as good crystal size in the fiber axis direction and good orientation of the molecular chain in the amorphous region, superior mechanical properties in the wet state compared to other fibers, but fibril in the fiber axis direction It is formed a lot, the binding force between the fibrils is weak, the external friction caused by the mechanical action during the wetting occurs a lot of fibrils on the fiber surface has a disadvantage of low elongation.

U. S. Patent No. 5,942, 327 reported a method for improving strength and elongation by controlling the tension acting on the yarn from nozzle to drying in spinning using the solution prepared by the above method.

However, when spinning high-polymerization cellulose pulp with a solution prepared to have a concentration of 12% or more, it is difficult to transfer the solution due to the high viscosity of the solution, and immediately after discharge in dry and dry spinning using a nozzle of 800 holes or more. Problems such as some truncation may occur in the air-gap.

In addition, H. Chanzy, M. Paillet and R. Hagege (Polymer, 31, 400-405 (1990) reported that the addition of salts to cellulose solutions can increase the strength, but the added salts may solidify and flush. It is difficult to remove cellulose decomposition products and increase the generation of fibrils by eluting in the process and adhering to the ion exchange resin during the recovery process of NMMO.

Until now, various methods for suppressing fibrils of cellulose fibers using NMMO have been proposed.

For example, U. S. Patent No. 5,310, 424 describes a method of inhibiting fibrillation by treating cellulose fibers with a chemical treatment agent having two to six functional groups that react with cellulose, wherein the chemical treatment agent is after spinning of the cellulose fibers. Treated without drying.

This method can effectively suppress fibrils, but the physical properties of the final fiber is poor. The method described in US Pat. No. 5,310,424 and PCT Publication No. WO 94/09191 treats precursors having an electrophilic carbon-carbon double bond or a chemical treatment agent having an electrophilic three-membered ring after the cellulose fibers are dried. In this case, the chemical treatment agent is applied to the fibers using a hot aqueous solution at a temperature of 40 ° C to 60 ° C.                         

This method has the disadvantage of being inefficient because it is hydrolyzed by water in the presence of alkali and loses activity.

In Japanese Patent Application Laid-Open No. 8-505120 or 8-508555, a polyethylene glycol or surfactant having a molecular weight greater than NMMO is added to a coagulation bath after spinning of cellulose fibers instead of a chemical treatment agent directly on the fiber. A method of suppressing brill has been proposed. At this time, decomposition products of polyethylene glycol or by-products or surfactants reacted after decomposition in the coagulation bath remain in the coagulation bath, which is a major problem in the recovery of NMMO.

In addition, German Patent Publication No. 1960-0572 discloses a method of inhibiting fibrils of cellulose fibers by containing ethanol in a post treatment bath and a washing bath, but this method has sufficient fibrillation resistance required for long fiber filaments. It could not be granted.

The present invention provides cellulose fibers excellent in physical properties such as steel and elongation, and fibrillation resistance, and the present invention provides high polymerization degree and high solubility of pulp powder even when manufactured using cellulose pulp having high α-cellulose content. It is an object of the present invention to provide a method for producing a cellulose fiber having excellent spinning workability due to suppressed increase in viscosity.

The present invention will be described in detail with reference to FIG. 1.

1) Cellulose sheet having high degree of polymerization (DP 1,000 ~ 1,600) and high α-cellulose content (95% or more) and cellulose sheet having low degree of polymerization (400 ~ 800) and low α-cellulose content (87% or less) Each grinder is used to form a powder of a predetermined size or less, that is, 1,000 μm or less.

If the thickness exceeds 1,000 mu m, the spinning solution becomes uneven because the solubility of each cellulose is poor and the mixing is poor, resulting in undissolved dissolution in the kneader or the extruder.

2) After the high and low polymerization cellulose powders prepared in 1) were added to the mixer at a constant ratio, they were mixed forcibly, transferred to a kneader or an extruder, and injected with a concentrated liquid NMMO to dissolve. It should be more than weight percent.

The mixing ratio of cellulose having low polymerization degree and low α-cellulose content (87% or less) is high polymerization degree, 10-50% by weight relative to cellulose having high α-cellulose content (95% or more), and preferably 15-30 Weight percent.

If less than 10% by weight of the solution viscosity is not large decrease, if it exceeds 50% by weight, the viscosity of the solution is increased but the physical properties are reduced, it is difficult to produce a good cellulose fiber properties.

3) The air-gap between the nozzle discharge and the coagulation bath is 0.5 to 30 cm, preferably 5 to 10 cm, when the NMMO solution of the dissolved cellulose mixture is wet-spun and the fiber is produced.

If it is less than 0.5 cm, the draw ratio of the desired physical properties cannot be obtained, and if it exceeds 30 cm, the fibers stick together before the fibers enter the coagulation bath to form an adhesive yarn.                     

4) The coagulation bath composition is 50 to 90% by weight of water / 10 to 50% by weight of NMMO, preferably 60 to 80% by weight / 20 to 40% by weight of NMMO.

If the water is less than 50% by weight, the coagulation is late, which is difficult to wash due to the high solvent concentration remaining in the fiber, and the maximum draw ratio is reduced because the strength of the fiber to be pulled during coagulation is low.

If the water exceeds 90% by weight, the recovery cost during the recovery of the solvent increases, which is bad in terms of economy.

5) The draw ratio is 6 times or more, and the drawn fibers are dried by hot air after tanning and wound by winder.

Physical properties of the cellulose fiber prepared by the production method of the present invention was measured as follows.

Viscosity measurement was performed at a shear rate of 1 sec ^-1 after dissolving at 110 ° C. for 20 minutes using a Brookfield viscometer.

In the solubility evaluation, the cellulose powder mixed in the reactor was added to the extruder by weight of 12% by weight based on monohydrate NMMO (monohydrate NMMO), and dissolved at 110 ° C. for 20 minutes, and the undissolved particles were evaluated by polarizing microscope.

S1 (drying strength): 107 ℃, strength after 2 hours drying (g / d)

S2 (wet strength): strength measured after conditioning at 25 ° C. and 65 RH for 24 hours (g / d)

E (shrinkage rate): Shrinkage rate (%) measured by standing at 177 ° C and 0.01g / d for 2 minutes                     

Fibrillation evaluation evaluated the fibrillation index (F.I.) using the following method.

Samples of the fibers were arranged corresponding to the increase in fibrillation.

The value obtained by measuring the reference fiber length from each sample, counting the number of fibrils according to the reference field, measuring the length of each fibrils, calculating the average fibrillation length, and then multiplying the number of fibrils by the average fibril length previously obtained. Was set for each fiber.

The fiber showing the highest value was the most fibrillated fiber, and the fifylation index was divided by any value.

The fibrillation index 0 was attached to the fibrillated fibers as a whole and the remaining fibers were arranged in random values in the range of 1 to 10.

Example 1

A cellulose sheet having a polymerization degree of 400 and an α-cellulose content of 85% (Weyerhaeuser) and a cellulose sheet having a polymerization degree of 1600 and an α-cellulose content of 98% (Buckeye) were pulverized to 500 µm or less, respectively, at a ratio of 20/80% by weight. After mixing in a mixer, the concentrated liquid NMMO was injected and dissolved at 110 ° C. for 20 minutes, so that the final concentration of the mixture was 12% by weight.

This was extruded through a 0.15 mm diameter nozzle to form a fiber, and then passed through a 100 mm air layer, followed by washing with water at 10 ° C. in a coagulation bath of 30% by weight of 70 / NMMO water, emulsion treatment and drying. It was wound up later.

Example 2                     

A cellulose sheet having a polymerization degree of 400 and an α-cellulose content of 85% (Weyerhaeuser) and a cellulose sheet having a polymerization degree of 1600 and an α-cellulose content of 98% (Buckeye) were mixed at a ratio of 50/50% by weight, respectively. The same procedure was followed.

Example 3

A cellulose sheet having a degree of polymerization of 800 and an α-cellulose content of 85% (Weyerhaeuser) and a cellulose sheet having a degree of polymerization of 1,600 and an amount of α-cellulose content of 98% (Buckeye) were mixed at a ratio of 20/80% by weight. / NMMO 20% by weight, the temperature was set to 20 ℃, the remaining conditions were carried out in the same manner as in Example 1.

Example 4

A cellulose sheet having a polymerization degree of 400 and an α-cellulose content of 85% (Weyerhaeuser) and a cellulose sheet having a polymerization degree of 1000 and an α-cellulose content of 90% (Tembec) was powdered and mixed at a ratio of 20/80% by weight in a mixer. The remaining conditions were carried out in the same manner as in Example 1.

Example 5

The cellulose sheet having a degree of polymerization of 800 and α-cellulose content of 85% (Weyerhaeuser) and the cellulose sheet having degree of polymerization of 1,000 and α-cellulose content of 90% (Tembec) were powdered and mixed at a ratio of 20/80% by weight in a mixer. The remaining conditions were carried out in the same manner as in Example 1.

Comparative Example 1

Polymerization degree 1600, α- cellulose content 98% (Buckeye Co., Ltd.) cellulose sheet was pulverized and injected into the extruder alone, the rest of the conditions were carried out in the same manner as in Example 1.

Comparative Example 2

A cellulose sheet having a polymerization degree of 400 and an α-cellulose content of 85% (Weyerhaeuser) and a cellulose sheet having a polymerization degree of 1,600 and an α-cellulose content of 98% (Buckeye) was respectively mixed in an 80/20% by weight ratio, and the remaining conditions were It carried out similarly to 1.

Comparative Example 3

A cellulose sheet having a polymerization degree of 400 and α-cellulose content of 85% (Weyerhaeuser) was pulverized and injected into the extruder alone, and the remaining conditions were carried out in the same manner as in Example 1.

              <Table 1>

Pulp polymerization degree: 400/1600 Viscosity Comparative Example 1      0/100% by weight    16000 Example 1      20/80 "    10500 Example 2      50/50 "     7500 Comparative Example 2      80/20 "     3500 Comparative Example 3     100/0 "     1500

<Table 2>

                Physical polymerization degree 400/1600  S1 (dry strength) (g / d)  S2 (Wet Strength) (g / d)  Shrinkage (%)  Fibril Index  Solubility Comparative Example 1 10/100% by weight 7.0 or higher 5.4 and above 1 or less 3-4 × Example 1 20/80 " 7.0 or higher 5.3 or higher 1 or less 1-2 ○ Example 2 50/50 " 6.5 5.0 1 or less 1-2 ○ Comparative Example 2 80/20 " 5.5 4.2 1 or less 1-2 ○ Comparative Example 3 100/0 " 5.2 4.0 1-2 One ◎

◎: very good solubility, ○: excellent solubility, Δ: solubility normal, ×: poor solubility                     

<Table 3>

           Physical polymerization degree (20: 80% by weight)  S1 (dry strength) (g / d)  S2 (Wet Strength) (g / d)  Shrinkage (%)  Fibril Index  Remarks Example 3 800: 1600 7.0 or higher 5.4 and above 1 or less 1-2 △ Example 4 400: 1000 7.0 or higher 5.3 or higher 1 or less 1-2 ○ Example 5 800: 1000 6.5 5.2 1 or less 1-2 ○

(Double-circle): Solubility very excellent, (circle): Excellent solubility, (triangle | delta): Solubility normal, x: Poor solubility.

As can be seen from Tables 1 to 3, the viscosity of the cellulose solution, the physical properties and the fibrillation index of the fibers prepared therefrom are greatly influenced by the mixing ratio depending on the degree of polymerization.

That is, when a solution having a concentration of 12% or more is prepared using a pulp having a high degree of polymerization (1,000 to 1,600) and a content of 95% or more of α-cellulose, a low degree of polymerization (400 to 800) and an α-cellulose content of 87% Mixing the pulp of 10 to 50% by weight, preferably 15 to 30% by weight was effective in increasing the stability of spinning and physical properties by decreasing the viscosity of the solution and increasing the solubility.

Cellulose fiber manufacturing method according to the present invention as described above has the following advantages.

In general, a method for reducing the viscosity of the solution is a method of reducing the concentration of the solution or dissolving the low degree of polymerization pulp, which is not good because it reduces the strength of the cellulose fibers and lowers the productivity.

There is also a way to lower the viscosity by increasing the spinning temperature as much as possible, but it promotes the decomposition of cellulose, thereby reducing the physical properties.                     

The present invention has a high degree of polymerization (DP 1,000 to 1,600), a cellulose powder having a high α-cellulose content (95% or more) and a low α-cellulose content (87% or less) while having a low polymerization degree (DP 400 to 800). By adding and mixing the cellulose powder with the appropriate ratio, the solubility caused by the use of the high polymerization cellulose powder is minimized, and the homogeneous solution can be obtained even in the same concentration solution. Fibers can be produced.

In addition, the present invention has the advantage of removing the difficulty of solution transfer due to the viscosity increase when dissolving the high polymerization degree cellulose, and improves the spinning stability by reducing the pressure applied to the nozzle pack during spinning.

In addition, the cellulose fiber according to the present invention is very excellent in physical properties such as steel, elongation and fibrillation resistance.

Claims (5)

In the method for producing high strength cellulose fibers by N-methyl morpholine-N-oxide / water mixed solvent, 90/10 to 50/50 weight of cellulose powder having a degree of polymerization of 1,000 to 1,600 and cellulose powder having a degree of polymerization of 400 to 800 A method for producing cellulose fibers, characterized in that the mixture is produced in a% ratio. The method for producing cellulose fibers according to claim 1, wherein the high degree of polymerization of cellulose powder contains 95% or more of α-cellulose. The method for producing cellulose fibers according to claim 1, wherein the low-polymerization cellulose powder contains not more than 87% of α-cellulose. Cellulose fibers prepared by the N-methylmorpholine-N-oxide / water mixed solvent, wherein the high degree of polymerization of cellulose having a polymerization degree of 1,000 to 1,600 and the low degree of polymerization cellulose having a degree of polymerization of 400 to 800 is 90/10 to 50/50% by weight. Cellulose fibers, characterized in that the mixture at a ratio of. The method for producing cellulose fibers according to claim 4, wherein the high polymerization cellulose contains 95% or more of α-cellulose, and the low polymerization cellulose contains 87% or less of α-cellulose.

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