KR20010061107A - Preparation for Celluose Solution using Pretreated Pulp - Google Patents

Abstract

PURPOSE: A manufacturing method of a uniform and transparent cellulose solution is provided by using a preprocessed pulp without removing moisture, and being useful for manufacture of a cellulose fiber, a dividing screen or a film having high quality. CONSTITUTION: The cellulose solution is obtained by preprocessing a cellulose pulp by 50-95deg.C of hot water to swell, and dissolving the swollen cellulose pulp in NMMO(N-methylmorpholine-N-oxide) aqueous solution. When the cellulose pulp is preprocessed, wet pick-up of the pulp is 75-200%. When the swollen cellulose pulp is dissolved, heating temperature is 60-130deg.C, preferably 70-120deg.C, most preferably 90-100deg.C.

Description

Preparation method of cellulose solution using pretreated pulp {Preparation for Celluose Solution using Pretreated Pulp}

The present invention relates to a method for producing a cellulose solution using pretreated pulp, and more particularly, to swelling by treating the cellulose pulp with hot water, wherein 13% of N is known as the best solvent for cellulose pulp. The present invention relates to a method for preparing a homogeneous and transparent cellulose solution suitable for making a fiber or a film by dissolving cellulose pulp pretreated in an aqueous solution of N-methylmorpholine-N-oxide (NMMO).

In general, the cellulose solution is used in the production of cellulose fibers or cellulose films, and since the method of dissolving cellulose pulp using a tertiary amine oxide solvent in US Patent No. 1,179,181 has been proposed, a method for producing a cellulose solution has been developed. It is becoming.

U.S. Patent Nos. 4,142,913, 4,144,080, 4,145,532, and 4,196,282 suggest a method of dissolving cellulose pulp by adding cellulose pulp to an NMMO aqueous solution and swelling to remove water under reduced pressure to create optimum dissolution conditions. It is. However, in the method of US Pat. No. 4,142,913, the swelling is insufficient to directly dissolve the cellulose pulp with NMMO having a low moisture content, so that NMMO may not penetrate into the inside of the cellulose and thus cannot be dissolved.

On the other hand, in the case of NMMO having a water content enough to swell, it is necessary to dissolve the cellulose while reducing the degree of hydration at the same time to continue to reduce the pressure, the process time is long, energy consumption is high, and the device is complicated.

U.S. Patent Nos. 4,246,221, 4,416,698 and 5,216,144 employ a method of removing water by using an NMMO aqueous solution containing excess water and depressurizing it. This implies a problem that is significantly reduced.

In addition, U.S. Patent No. 4,211,574 discloses a method of dissolving cellulose pulp with an aqueous NMMO solution having a water content of about 10%. In this case, the solubility decreases so that the cellulose pulp floats on the surface and is homogeneous. It is difficult to obtain a cellulose solution. Therefore, the process of removing the undissolved cellulose pulp floating on the surface is additionally required, and problems may occur in the spinning process when the spinning solution of cellulose fibers is used.

As described above, in the conventional method for producing a cellulose solution, when using an aqueous NMMO solution having a low hydration rate, it is difficult to prepare a completely dissolved cellulose solution, and it is difficult to obtain a homogeneous cellulose solution. In the case of using an aqueous solution, it takes a lot of time and energy to lower the degree of hydration and there is a problem that the degree of polymerization of cellulose is significantly reduced.

An object of the present invention is to overcome the above-mentioned problems, characterized in that the cellulose pulp is pretreated with hot water to swell and then completely dissolve the cellulose pulp in NMMO aqueous solution of a suitable degree of hydration, It is to provide a manufacturing method.

The present invention relates to a method for producing a cellulose solution, comprising the steps of pre-swelling and swelling the cellulose pulp with hot water and dissolving the swelled cellulose pulp completely in an NMMO aqueous solution by the previous step.

Hereinafter, the present invention will be described in detail.

In the case of preparing a cellulose solution, the cellulose sheet is first cut into a board of a predetermined size, and then pretreated with hot water at room temperature, more preferably at a temperature of 50 to 95 ° C., and completely swollen. At this time, if the wet pick-up of the pulp is less than 75%, the swelling does not occur sufficiently and the dissolution is not complete. If the pulp is more than 200%, it does not help to increase the solubility of the pulp by the swelling.

It is preferable that the processing time of a cellulose board by hot water shall be 5 second-10 minutes.

Subsequently, the swelled cellulose board is added to a static mixer containing NMMO aqueous solution and dissolved therein, wherein the heating temperature is 60 to 130 ° C., more preferably 70 to 120 ° C., and most preferably 90 It is good to keep it at -100 degreeC.

The cellulose solution prepared in this way can be directly applied to the production of cellulose fibers, separators or films by adding a continuous processing process. For example, in the case of manufacturing the filament by wet-dry spinning the solution, the height of the air gap is 10 to 15 cm, the stretching ratio is 5 to 10 times, and the composition of the coagulation solution is 70 to 90% of water and 10 to 30% of NMMO. You can do At this time, by continuously cross-linking the spun filament yarn in the Nelson roller can reduce the fibrillation and can produce a high strength filament yarn. After crosslinking with a nels roller, it is dried with a dryer to wind up the filament yarn.

The present invention is 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>

In the present embodiment, the method of measuring the degree of polymerization of cellulose is as follows. Intrinsic viscosity (IV) of cellulose was measured using the following formula (1) from the relationship about the value of the specific viscosity with respect to each density | concentration based on ASTMD539-51T. The polymerization degree of cellulose was computed by the following formula (2) which shows the relationship between the intrinsic viscosity calculated | required from Formula (1), and a polymerization degree.

DP = 1.71 × 10 ² IV ^1.1

<Example 1>

Sheet-shaped cellulose pulp (Buckeye Cellulose Corporation, Grade V-5S, degree of polymerization; 1643) was cut into a size of 3 mm x 3 mm and hydrothermally treated at 85 ° C. to increase the weight by 120 wt%. The cellulose pulp treated in this way was brought to 10 wt% of 87% NMMO aqueous solution and put together into a static mixer. At this time, the temperature in the static mixer was kept constant at 95 ℃. The degree of polymerization of the prepared cellulose solution was 1460. The solution was observed using a polarizing microscope to obtain a homogeneous solution without any undissolved cellulose.

<Example 2>

A cellulose solution was prepared in the same manner as in Example 1 except for using cellulose having a degree of polymerization of 1192 (Buckeye Cellulose Corporation, Grade V-81) and changing the dissolution temperature to 90 ° C. The degree of polymerization of the prepared cellulose solution was 1080, and the solution was observed using a polarizing microscope to obtain a homogeneous solution without any undissolved cellulose.

<Example 3>

A cellulose solution was prepared in the same manner as in Example 2 except for using cellulose having a degree of polymerization of 819 (Buckeye Cellulose Corporation, Grade V-60) and changing the dissolution temperature to 85 ° C. The degree of polymerization of the cellulose solution thus prepared was 778. As a result of observing the solution using a polarizing microscope, a homogeneous solution without any undissolved cellulose was obtained.

<Example 4>

The same method as in Example 1, except that cellulose having a degree of polymerization of 819 (Buckeye Cellulose Corporation, Grade V-60) was used and the dissolution temperature was changed to 95 ° C and the cellulose pulp was 15wt% compared to 87% NMMO aqueous solution. It was carried out to prepare a cellulose solution. The degree of polymerization of the cellulose solution thus prepared was 747. As a result of observing the solution using a polarizing microscope, a homogeneous solution without any undissolved cellulose was obtained.

Comparative Example 1

A cellulose solution was prepared in the same manner as in Example 1, except that the pretreatment process was not performed by hot water. As a result of observing the prepared cellulose solution with a polarizing microscope, there was a large amount of undissolved cellulose fibers.

Comparative Example 2

A cellulose solution was prepared in the same manner as in Example 2, except that the step of pretreatment with hot water was not performed. As a result of observing the prepared cellulose solution with a polarizing microscope, there was a large amount of undissolved cellulose fibers.

According to the present invention, it is possible to prepare a very homogeneous and transparent cellulose solution without the need to remove moisture by depressurizing during the cellulose dissolution process, and the cellulose solution thus obtained is directly applied to the production of high-quality cellulose fibers, separators or films by additional processes. Can be.

Claims (3)

In preparing the cellulose solution, the cellulose pulp is pretreated with hot water to swell, and the cellulose pulp completely swelled by the step is dissolved in NMMO aqueous solution. The method for producing a cellulose solution according to claim 1, wherein cellulose pulp swelled by hot water at a temperature of 50 to 95 ° C is used. The method for producing a cellulose solution according to claim 1 or 2, wherein the wet pick-up of the pulp at the time of pretreatment with hot water is 75 to 200%.