KR20030079053A - Cellulose fiber and its manufacturing process - Google Patents

Abstract

PURPOSE: Cellulose fiber is characterized by having over 6.0g/denier of dry strength, over 4.0g/denier of wet strength, under 1% of shrinkage and under 1 of fibril index, increasing shape stability and increasing fatigue resistance. A manufacturing method thereof is characterized by giving adhesion between fibrils, not eluting PVA, optimizing a coagulating process and a washing process, drawing second the fiber after coagulating cellulose and improving physical properties. The fiber is useful for a tire cord. CONSTITUTION: The cellulose fiber is obtained by the steps of: melting cellulose powder and PVA powder into N-methyl morpholine N-oxide(NMMO) aqueous solution to get a mixed solution; extruding the mixed solution into a coagulating bath of the NMMO aqueous solution to coagulate; washing the fiber; heat-drawing second the fiber; and then oiling the fiber.

Description

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

The present invention relates to a cellulose fiber having a high strength, a low shrinkage rate and excellent fibrillation resistance, and a method of manufacturing the same.

In general, the regenerated cellulose fibers have been stretched from the nozzle entrance to the coagulation bath during the wet and dry spinning, and after solidification, the stretching was difficult due to the inherent structural characteristics of the cellulose fibers.

The present invention relates to a cellulose fiber and a method for producing the same, by adding a large amount of PVA to the cellulose powder so that the cellulose can be stretched even after the cellulose has solidified to improve physical properties and fibrillation resistance.

U.S. Pat. A method of preparing tertiary amine oxide based cellulose fibers by dissolving cellulose while being swelled and swelling at the same time and continuing to depressurize to remove moisture has been proposed.

Cellulose fibers prepared by the above method has a number of advantages, such as excellent mechanical properties in the wet state and give a soft feeling in terms of sensitivity compared to other fibers, but fibril is formed a lot in the direction of the fiber axis, the binding force between the fibrils Because of this weakness, when there is external friction due to mechanical action during wetting, fibril is generated a lot on the surface of the fiber, which makes dyeing and processing difficult.

So far, various methods for inhibiting fibrils have been proposed among the manufacturing methods of cellulose fibers using NMMO as a solvent.

For example, U. S. Patent No. 5,310, 424 describes a method of inhibiting fibrillation by treating undried cellulose fibers after spinning with a chemical treatment agent having 2 to 6 functional groups reacting with cellulose. Although effective in suppressing fibrils, there is a problem in that the physical properties of the final fiber are poor.

In addition, the method described in U.S. Patent No. 5,310,424 and PCT Publication No. WO-94 / 09191 discloses a precursor having an electrophilic carbon-carbon double bond or a chemical treatment agent having an electrophilic three-membered ring on the cellulose fibers after drying. As a treatment method, the chemical treatment agent is applied to the fiber using a hot water solution of 40 ℃ ~ 60 ℃ This method is a disadvantage that the treatment effect is poor because the chemical treatment agent is hydrolyzed by water in the presence of alkali and loses activity There is this.

Unlike Japanese Patent Application Laid-Open No. 8-505120 or Japanese Patent Application Laid-open No. 8-508555, polyethylene glycol or a surfactant having a molecular weight greater than NMMO in a coagulation bath after spinning cellulose fibers is different from a method of directly treating a chemical treatment agent on the fiber. A method of suppressing fibrils by adding is proposed.

These methods have a lot of difficulties in recovering NMMO because decomposing products of polyethylene glycol in the coagulation bath or by-products or surfactants produced after decomposition remain in the coagulation bath.

German Patent Publication No. 1960-0572 discloses a method of inhibiting fibrils of cellulose fibers by containing ethanol in a post-treatment bath or a washing bath, but this method gives sufficient fibril resistance required for long fiber filaments. I could not.

The present invention mixes and dissolves cellulose powder and a large amount of PVA powder in an NMMO aqueous solution, and extrudes it to prepare cellulose fibers while optimizing coagulation and washing conditions and adding a second hot drawing process to increase dry, wet strength and shrinkage. It is an object of the present invention to provide a cellulose fiber having a low fibrillation resistance and a method of manufacturing the same.

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

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

1) A cellulose sheet having a polymerization degree of 700 to 1,200 is made into a powder form of a predetermined size or less, that is, 1,000 μm or less by using a grinder. If the thickness exceeds 1,000 μm, the miscibility with PVA is deteriorated, and the undissolved spinning solution is generated by dissolving in the extruder, resulting in a non-uniform spinning solution.

2) The polymerization degree of the used PVA powder is 1,500-5,000, Preferably it is 1,700-3,500.

3) Cellulose powders of 1) and 2) and PVA powders are forcibly mixed in a mixer and then injected into an extruder.Then, the concentrated liquid NMMO is injected thereinto, after dissolving the mixture, the final concentration of the mixture is 5 To 15% by weight.

If the final concentration is less than 5% by weight is not good physical properties, if it exceeds 15% by weight is not good because a lot of undissolved components occur.

When the two components are mixed, the PVA is preferably 1 to 60% by weight based on the weight of the mixture of cellulose and PVA, preferably 5 to 30% by weight.

If less than 1% by weight, the increase in physical properties is not large, and the draw ratio as desired at the time of secondary stretching cannot be obtained.

If it exceeds 60% by weight, excess PVA in the fiber is partially eluted by water during the coagulation and washing process, which increases the recovery cost of the solvent and loses its inherent properties as a cellulose fiber.

4) When manufacturing fibers by wet-dry spinning NMMO solution of homogenized cellulose and PVA mixture, the air-gap between nozzle discharge and coagulation bath should be 0.5 ~ 30cm. Preferably it is 5-10 cm.

If it is less than 0.5 cm, the draw ratio of the desired physical properties cannot be obtained. If it exceeds 30 cm, the fibers are bonded to each other before the fibers enter the coagulation bath to form an adhesive yarn.

5) 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 and the concentration of the solvent remaining in the fiber is high, which makes it difficult to wash the water, 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, it is uneconomical because it increases the recovery cost during solvent recovery.

6) The coagulation bath temperature should be 0 to 30 ° C. The higher the coagulation bath temperature, the higher the diffusion rate and the lower the concentration of the solvent in the coagulated fiber, which improves the flushing effect. However, when the coagulation bath temperature is higher than 30 ° C, the fiber property is reduced and some PVA is eluted. Increasing the remaining solvent reduces the flushing effect and increases the energy cost to maintain the temperature.

Preferably, considering the degree of polymerization of PVA, the coagulation bath temperature is most preferably 5 to 15 ° C.

7) The draw ratio (primary draw) from the nozzle entrance to the coagulation bath is 0 to 5 times.

8) The temperature of the water washing bath is 5 to 20 ° C, and the process cost is high at less than 5 ° C, and it is economically inefficient.

9) Secondary stretching is hot stretching, and the draw ratio is 1.5 to 3 times, and hot stretching is dry heating, using hot air heating furnace, contact heater, using heating roller individually or using these methods. It can also be used in combination.

Although the stretching temperature is not limited, it is preferably 120 ° C. or higher, and the stretching ratio is controlled by the roller speed ratio between the inlet and the outlet, and the stretching ratio of the primary stretching × secondary stretching is preferably 7 times or more. This is because physical properties can be obtained.

10) The second drawn fiber is dried by hot air after tanning and wound by winder.

The physical properties of the cellulose fibers produced in the present invention were measured as follows.

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 (%) Fibrillation evaluation measured by standing at 177 degreeC and 0.01g / denier for 2 minutes was evaluated by the fibrillation index (F.I.) using the following method.

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

From each sample, the reference fiber length is measured, the number of fibrils according to the reference fiber length is counted, the length of each fibrils is measured, the average fibrillation length is calculated, and the number of fibrils is multiplied by the average fibril length previously obtained. The obtained values were determined for each fiber.

The fiber showing the highest value was the most fibrillated fiber, and the fibrillation 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

The cellulose having a degree of polymerization of 800 was pulverized below 500 μm, mixed with PVA powder having a degree of polymerization of 1700 and 70/30% by weight, respectively, in a mixer, injected into an extruder, and injected with concentrated liquid NMMO under reduced pressure. Weight percent.

After the pasteurization and melting process in the extruder, it was extruded through a nozzle having a diameter of 0.15 mm, and then passed through a 100 mm air layer, followed by a temperature of 10 ° C. and a composition ratio of 70 / NMMO 30 wt% of water, followed by coagulation. It was wound up after washing with water, secondary stretching, tanning and drying at < RTI ID = 0.0 > At this time, the primary draw ratio × secondary draw ratio was 8 times (Table 1).

Example 2

PVA having a degree of polymerization of 3,500 was used, and the composition ratio of the mixture was cellulose 80 / PVA 20% by weight, and the composition ratio was 80 / NMMO 20% by weight of water and the temperature was 20 ° C., and the remaining conditions were performed in the same manner as in Example 1. Table 1

Example 3

Primary draw ratio x secondary draw ratio was 12 times and the rest of the conditions were carried out in the same manner as in Example 1. (Table 1)

Example 4

The resultant was solidified in a coagulation bath having a temperature of 20 ° C. and a composition ratio of water 70 / NMMO 30% by weight, and wound up at 20 ° C. after washing with water, secondary stretching, emulsion treatment and drying.

The primary draw ratio × secondary draw ratio was 8 times and the rest of the conditions were carried out in the same manner as in Example 1. (Table 1)

Comparative Example 1

Cellulose having a degree of polymerization of 800 is pulverized below 500 μm and injected into an extruder, and the concentrated NMMO concentrated by distillation under reduced pressure is injected so that the final concentration of cellulose is 13% by weight.

After pasting and dissolving in an extruder, the fiber extruded through a 0.15 mm diameter nozzle solidified in a coagulation bath having a temperature of 15 ° C. and a composition ratio of 70 / NMMO 30% by weight of water after passing through a 10 mm air layer. It was wound up after washing with water, tanning and drying.

The primary stretching was eight times (Table 1).

<Table 1>

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 S1 (dry strength, g / denier) 6.1 6.3 6.5 6.0 4.9 S2 (wet strength, g / denier) 4.2 4.3 4.4 4.1 2.6 E (shrinkage,%) 1 or less 1 or less 1 or less 1 or less 1 or less Fibril Index One One One One 7

Cellulose fibers according to the present invention has a very good physical properties with a dry strength of 6.0g / denier or more, a wet strength of 4.0g / denier or more, a shrinkage of 1% or less, and a fibrillation index of 1 or less, and also has excellent fibrillation resistance.

As described above, the cellulose fiber according to the present invention can be used as a tire cord fiber applied to a carcass part of a radial tire for a passenger car because of high strength, low shrinkage ratio, and excellent fibrillation resistance.

That is, by applying the tire cord made of the cellulose fiber according to the present invention to the carcass of the radial tire for passenger cars, the fatigue resistance and form stability of the tire can be improved, and after vulcanization, unlike the usual method at the time of tire manufacturing, Since the expansion process can be omitted, the tire manufacturing time can be shortened and the energy used can be reduced.

The method for producing cellulose fibers according to the present invention has the following advantages.

First, PVA gives the adhesive force between fibrils and fibrils of cellulose fibers to produce cellulose fibers with more excellent physical properties. Cellulose fibers can be prepared.

Second, general wet and dry spinning, in particular, the wet and dry spinning of the regenerated cellulose fibers is carried out until all the stretching from the nozzle inlet to the coagulation bath, and after coagulation had difficulty in stretching due to the inherent structural characteristics of the cellulose fibers, the present invention By adding a large amount of PVA, secondary stretching is possible even after cellulose has solidified, thereby improving physical properties of the cellulose fibers.

Claims (7)

A cellulose fiber containing a PVA (polyvinyl alcohol) component, which satisfies all of the following physical properties. Below Dry strength (S1); 6.0 g / denier or more Wet strength (S2); 4.0 g / denier or more Shrinkage rate; 1% less than Fibrillation index; 1 or less However, S1 (dry strength): 107 ° C, strength after drying for 2 hours (g / denier) S2 (wet strength): strength measured after conditioning at 25 ° C. and 65 RH for 24 hours (g / denier) E (shrinkage rate): Shrinkage rate (%) measured by standing at 177 ° C. and 0.01 g / denier for 2 minutes. Dissolving cellulose powder and PVA powder in N-methyl morpholine N-oxide (NMMO) aqueous solution to form a mixed solution, and the mixed solution is coagulated by extruding in a coagulation bath of NMMO aqueous solution, followed by hot stretching secondly after washing. The manufacturing method of the cellulose fiber. The method of claim 2, wherein the PVA is 1 to 60% by weight based on the weight of the mixture of cellulose and PVA. The method for producing cellulose fibers according to claim 2, wherein the final concentration of the mixed solution is 5 to 15% by weight. The method for producing cellulose fibers according to claim 2, wherein the coagulation bath is composed of 50 to 90% by weight of water and 10 to 50% by weight of NMMO, and the temperature of the coagulation bath is 0 to 30 ° C. The method for producing cellulose fibers according to claim 2, wherein the washing temperature is 5 to 20 ° C. The method for producing cellulose fibers according to claim 2, wherein the secondary draw ratio is 1.5 to 3.0 times, and the value of primary stretch x secondary stretch is 7 times or more.