KR100402724B1 - Process for preparing a cellulose fibre - Google Patents

Abstract

The present invention is a method for producing cellulose fibers prepared by wet and dry spinning with a solution consisting of cellulose, N-methylmorpholine-N-oxide aqueous solution and polyvinyl alcohol.

The present invention can produce cellulose fibers that suppress fibril generation and are excellent in flexibility and strength.

Description

Process for preparing a cellulose fiber

The present invention is not only physical properties but also fibrillation resistance of the final fiber by adding polyvinyl alcohol in the step of making a spinning solution with an aqueous solution of cellulose and N-methylmorpholine-N-oxide (hereinafter abbreviated as NMMO) to prepare cellulose fibers. A method for producing this excellent cellulose fiber.

As already described in U.S. Patent Nos. 4,142,913, 4,144,080, 4,196,282, 4,246,221, 4,211,574, and 4,416,698, cellulose was added to NMMO aqueous solution to swell and at the same time continue to swell. A method for producing a tertiary amine oxide-based cellulose fiber has been reported, in which cellulose is dissolved to produce fiber by dissolving cellulose while decompressing water under reduced pressure.

Cellulose fibers produced at this time has many advantages, such as excellent mechanical properties in the wet state and give a soft feeling in terms of sensitivity compared to other fibers, but the fibril is formed in the direction of the fiber axis, the binding force between the fibrils It is weak, and the external friction by mechanical action during wetting causes a lot of fibrils on the surface of the fiber, which makes dyeing and processing difficult.

Until now, various methods for suppressing fibrils of cellulose fibers prepared using NMMO as a solvent 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 cellulose fiber is spun. It is then treated in an undried state.

This method can effectively suppress fibrils, but the physical properties of the final fiber is poor.

The method described in US Pat. Nos. 5,310,424 and WO-94 / 09191 is a method of treating a precursor 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 fiber using a hot aqueous solution of 40 ℃ to 60 ℃, this method has a drawback that the efficiency is lost due to the loss of activity due to hydrolysis by water in the presence of alkali.

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

German Patent Publication No. 19600572 proposed a method of inhibiting fibrils of cellulose fibers by containing ethanol in a post treatment bath and a washing bath, but did not have the fibrill resistance required as long fiber filaments.

The present invention has been made to provide a method for producing a cellulose fiber excellent in physical properties and excellent fibrillation resistance.

The present invention is characterized by a method for producing cellulose fibers, including a step of simultaneously dissolving cellulose and polyvinyl alcohol in N-methylmorpholine-N-oxide (NMMO). As follows.

1) A cellulose sheet having a polymerization degree of 700 to 1,200 is formed into a powder form of a predetermined size or less, that is, 5,000 μm or less by using a grinder.

2) 5 to 12% by weight of cellulose in powder form, an aqueous solution of N-methylmorpholine-N-oxide (hydrate n = 1.0 to 2.0), and a degree of polymerization of 1,500 to 5,000, more preferably 1,700 to 3,500 of polyvinyl alcohol. The mixture is introduced into a kneader, a static mixer, or a screw extruder having a temperature of 80 to 110 ° C, mixed well, and dissolved in a paste phase.

The polyvinyl alcohol is 0.5 to 8% by weight, but less than 0.5% by weight does not properly exhibit the adhesion between the fibrils to achieve the desired fibrillated control properties, when exceeding 8% by weight in excess of the fiber bundle The polyvinyl alcohol may be eluted by hot water in post-processing. In addition, when the degree of polymerization of polyvinyl alcohol (PVA) is less than 1,500, the PVA component is improved in cellulose fiber (lyocell fiber), that is, fibril resistance and strength. Since it does not contribute to the improvement of PVA and exceeds 5,000, it is difficult to dissolve PVA, which causes excessive energy loss due to the high temperature and long time required for dissolution, as well as the PVA component that is not completely dissolved in the coagulation bath. A problem arises.

3) The content of syndiotactic diamond in polyvinyl alcohol is 50 to 70%, and more preferably 62 to 65% polyvinyl alcohol is used. The content of syndiotactic diamond is determined by the crystallinity of PVA. If the content is less than 50%, the crystallinity of PVA is low, so that the lyocell fiber does not contribute to the improvement of physical properties, that is, the improvement of fibril resistance and strength, and exceeds 70%. The crystallinity of PVA is so high that it not only reduces the flexibility of the lyocell fiber but also generates a lot of fibrils on the surface of the lyocell fiber.

4) The filaments are manufactured by wet and dry spinning NMMO solution of homogenized cellulose and polyvinyl alcohol blend. The height of air gap is 0.5 ~ 30cm, the draw ratio is 1 ~ 20 times and the composition of coagulant is water. 70 to 95% / NMMO 5 to 30%.

And the temperature of a coagulation liquid shall be 20-50 degreeC.

5) The solidified filament is dried and wound on a winder.

Physical properties of the cellulose fiber prepared in the present invention was measured as follows.

S1 (dry strength): 107 ° C., strength after drying for 2 hours (g / d).

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

E (shrinkage rate): 177 degreeC.

Shrinkage (%) measured by standing at 0.01 g / d for 2 minutes.

Fibrillation evaluation 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, a reference fiber length was measured to count fibrils according to the reference field, the length of each fibrils was calculated, the average fibrillation length was calculated, and the fibrillation number was multiplied by the average fibril length previously obtained. Values were set for each fiber.

The fiber showing the highest value was the most fibrillated fiber, and the fibrilation index was divided by an arbitrary value.

Fibrillation index 0 was attached to the fibrillated fiber as a whole, and the remaining fibers were arranged at random values in the range of 1 to 10.

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention as described only for the purpose of illustration.

Example 1

The cellulose having a degree of polymerization of 800 was pulverized to 1,500 µm, and the cellulose concentration was 12% by weight, and 85% by weight of an aqueous solution of N-methylmorpholine-N-oxide (hydrate n = 1.2) and 3% by weight of polyvinyl alcohol having a degree of polymerization of 1,700 were added to the static mixer. After the addition, the cellulose fibers were prepared by dissolving into paste.

And the syndiotactic diamond content of the polyvinyl alcohol used was 55% (Table 1).

Example 2

In Example 1 polyvinyl alcohol having a polymerization degree of 2,600 was used (Table 1).

Example 3

In Example 1 polyvinyl alcohol having a polymerization degree of 3,500 was used (Table 1).

Example 4

In Example 1, the content of polyvinyl alcohol was adjusted to 0.5% by weight (Table 1).

Example 5

In Example 1, the content of polyvinyl alcohol was adjusted to 5% by weight (Table 1).

Example 6

In Example 1, the content of polyvinyl alcohol was adjusted to 8 wt% (Table 1).

Example 7

In Example 1, polyvinyl alcohol having a syndiotactic diamond content of 50% was used (Table 1).

Example 8

In Example 1, polyvinyl alcohol having a syndiotactic diamond content of 60% was used (Table 1).

Comparative Example 1

Cellulose fiber having a degree of polymerization of 800 was pulverized to 1,500 µm and cellulose concentration was 12% by weight, 88% by weight of an aqueous solution of N-methylmorpholine-N-oxide (hydrate n = 1.2) was added to the static mixer, and then dissolved in a cellulose fiber. Was prepared (Table 1).

<Table 1>

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 S1 dry strength (g / d) 4.8 4.8 4.6 4.5 4.9 5.2 4.6 5.0 4.2 S2 Wet Strength (g / d) 3.4 3.2 3.1 3.2 3.4 3.5 3.2 3.4 2.6 E Shrinkage (%) 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less 1 or less Fibril Index 2 3 4 4 2 One 4 One 8

The present invention as described above has the following advantages.

First, the present invention is simpler and easier than the conventional fibrill control method of cellulose fibers.

In the conventional method, the solution is treated in the solidification process after the spinning of the solution or a control method through post-processing is used. However, the present invention can achieve excellent fibril control characteristics through easy operation in the solution manufacturing step.

Second, due to the characteristics of polyvinyl alcohol, it is possible to prepare cellulose fibers having more excellent physical properties by giving adhesion between fibrils and fibrils of cellulose fibers. Especially, the syndiotactic diamond in polyvinyl alcohol has a high crystallinity. It can make a greater contribution to physical property improvement.

Claims (3)

5-12 wt% cellulose, 80-94.5 wt% N-methylmorpholine-N-oxide aqueous solution, 0.5-8 wt% polyvinyl alcohol having 1,500-5,000 polymerization degree and 50-70% syndiotactic diamond content Method for producing a cellulose fiber, characterized in that the production using a solution consisting of. delete delete