CN110042488B

CN110042488B - Low-cost, green and efficient preparation method of high-strength cellulose filaments

Info

Publication number: CN110042488B
Application number: CN201910329135.5A
Authority: CN
Inventors: 张俐娜; 涂虎
Original assignee: Wuhan University WHU
Current assignee: Wuhan University WHU
Priority date: 2019-04-23
Filing date: 2019-04-23
Publication date: 2020-07-24
Anticipated expiration: 2039-04-23
Also published as: CN110042488A

Abstract

The invention discloses a preparation method of high-strength cellulose filaments with low cost, greenness and high efficiency. The solvent prepared by optimizing the ratio of sodium hydroxide/urea/zinc oxide is pre-cooled to-20 to-8 ℃, and can quickly dissolve high-ratio cellulose. Spinning 4-10% cellulose solution by adopting a wet spinning method, regenerating and solidifying in a mixed solution of citric acid, sodium citrate, ethylene glycol and water (the concentration is preferably 5-35%, 2-20%, 5-60% and 10-70% respectively), and the temperature of a solidifying bath is preferably 0-25 ℃. And carrying out primary stretching orientation, water washing and drying to obtain the regenerated cellulose filaments. The solvent and the coagulating bath selected by the method have low cost, and the prepared cellulose filaments are constructed by nano fibers and have excellent mechanical properties; the cellulose solubility is higher after the solvent composition proportion is optimized, and the production efficiency is also obviously improved; the production process is simple, safe and pollution-free, and is a green process for producing pure cellulose filaments. The method is expected to replace the existing industrialized spinning process.

Description

Low-cost, green and efficient preparation method of high-strength cellulose filaments

Technical Field

The invention belongs to the field of natural polymer material processing, and particularly relates to a low-cost, green and efficient preparation method of high-strength cellulose filaments.

Background

There are several methods for wet spinning of cellulose, the most common method in China at present is the viscose method, which still dominates in the domestic fiber production industry. However, the production process of viscose is not ideal, and CS is accompanied in the production process₂、H₂In addition, L yocel fiber can be prepared by dissolving cellulose by using an environment-friendly solvent N-methylmorphine-N-oxide through spinning, compared with viscose fiber, L yocel fiber has higher mechanical property and excellent dimensional stability, but the solvent is expensive and difficult to recover, and the conditions for dissolving cellulose are harsh, so the development of L yocel fiber is limited.

Patent CN 107653502A adopts phytic acid as a coagulating bath to prepare high-strength fiber yarns constructed based on nanofibers. However, the phytic acid is high in price, and the production cost is greatly increased.

Disclosure of Invention

In order to solve the technical problems, the invention provides the cellulose filament which is low in cost, green and capable of being industrially produced with high efficiency and the preparation method thereof.

The invention utilizes alkali/urea/zinc oxide/water as a solvent system, and the solvent system can effectively dissolve high-concentration cellulose after optimizing the proportion of each component, has low cost and environmental protection, and the high-concentration solution is beneficial to improving the production efficiency of spinning. In the subsequent coagulation spinning process, a cheap citric acid/sodium citrate/ethylene glycol/water mixed solvent is adopted as a coagulation bath, the coagulation bath can delay Brownian motion and diffusion among substances and exchange among solvents/non-solvents, so that the alkali-urea inclusion compound on the surface of cellulose molecules can be slowly destroyed by the coagulation bath to expose cellulose chains, the exposed cellulose chains are spontaneously arranged in parallel (arranged in the length direction) in a mild environment and then form nano fibers through intermolecular hydrogen bond action, and the mechanical strength of the nano fibers is obviously improved. The fiber yarn provided by the invention has high fiber strength, and can reduce the production cost while ensuring the high strength of the fiber yarn. The method for preparing the cellosilk has the advantages of simple process flow, cheap and easily-obtained raw materials, low equipment requirement, short production period and contribution to cost control and industrialization.

The technical scheme provided by the invention is as follows:

a preparation method of high-strength cellulose filaments with low cost, green and high efficiency comprises the following steps:

(1) dissolving high-concentration cellulose by using a solvent body prepared from alkali/urea/zinc oxide/water;

(2) preparing high-strength cellulose filaments constructed based on nano fibers by using a mixed solution of citric acid/sodium citrate/ethylene glycol/water as a coagulating bath through an extruder;

(3) soaking the cellulose filaments in a water bath for drawing and wire drawing;

(4) and then washing, oiling and drying to obtain the oil-water-based paint.

The fiber obtained in the step (1)The viscosity average molecular weight of the vitamin is less than 1.5 × 10⁵。

In the step (1), the solvent is pre-cooled to-20 to-8 ℃, then the cellulose is added, and the mixture can be completely dissolved after being stirred at high speed.

The alkali in the solvent in the step (1) is sodium hydroxide

In the step (1), the concentration of the alkali in the solvent is 5-10 wt%, the concentration of the urea is 5-20 wt%, the concentration of the zinc oxide is 0.5-5 wt%, and the balance is water.

In the step (2), the contents of citric acid, sodium citrate, ethylene glycol and water are respectively 5-35 wt%, 2-20 wt%, 5-60 wt% and 10-70 wt%.

The temperature of the coagulation bath in the step (2) is 0-25 ℃.

The extrusion rate of the extruder in the step (2) is 3-10 m/min.

The temperature of the water bath in the step (3) is 40-85 ℃.

The drawing in the step (3) is a secondary drawing, and the drawing rate is 1.2-2.8 (1.0 is not drawn).

The invention also provides the high-strength cellulose filaments prepared by the method.

The invention has the beneficial effects that:

(1) the components of the solvent and the coagulating bath are cheap and easy to obtain, and silk materials constructed based on the nanofibers can be regenerated in the coagulating bath, the arrangement of the nanofibers along the length direction is beneficial to improving the tensile strength, and the mechanical strength of the silk materials is higher than that of viscose;

(2) the optimized components and proportion of the solvent and the coagulating bath improve the solubility of the cellulose and the production efficiency;

(3) the spinning period is greatly shortened, the whole process from dissolution to filamentation only needs 8 hours, and the spinning time is far lower than that of the traditional viscose spinning method;

(4) the method is green, environment-friendly, energy-saving and consumption-reducing, does not need processes such as sulfonation, desulfurization and bleaching in the production process, does not generate toxic gas, and accords with the sustainable development road;

(5) simple process, low cost and industrial production.

Drawings

FIG. 1 is a surface and cross-sectional topographical view of cellulose filaments prepared in example 1;

FIG. 2 is a graph of the mechanical properties of the cellulose filaments prepared in example 2.

Detailed Description

The technical solutions of the present invention are further explained below by means of specific examples and figures, which are intended to help the better understanding of the contents of the present invention, but these specific embodiments do not limit the scope of the present invention in any way. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

Example 1

Preparing 1000g of a solvent of 5 wt% of NaOH/20 wt% of urea/0.5 wt% of ZnO/74.5 wt% of water, precooling the solvent to-20 ℃, adding 75 g of cellulose into the solvent, stirring at normal temperature, and completely dissolving the cellulose after 5 minutes. And (4) centrifuging for 5 minutes by using a centrifuge at 3000r/min to defoam to obtain clear and transparent cellulose spinning solution.

Pouring the spinning solution into a sealed tank, immersing a spinning head into a coagulating bath consisting of 10 wt% of citric acid/2 wt% of sodium citrate/18 wt% of ethylene glycol/70 wt% of water, and controlling the extrusion rate of the spinning solution to be 3 m/min and the temperature of the coagulating bath to be 25 ℃. The spinning solution is coagulated and formed into filaments after entering a coagulating bath, the filaments are collected by a roller and then drawn into a thermostatic bath filled with water of 50 ℃, the ratio of the rotating speed of the roller at the two ends of the thermostatic bath is controlled to be 1.2, and the cellulose filaments with the drawing ratio of 1.2 are obtained. And washing, drying and collecting coils to obtain the high-strength cellulose filaments.

The fiber structure of the round shape can be seen by observing the spun cellulose filament (figure 1) through a Scanning Electron Microscope (SEM), and the cross section appearance of the filament proves that the inside of the cellulose filament is really composed of nano fibers with the diameter of about 30-40 nanometers, and the structure is helpful for improving the mechanical property of the filament.

Example 2

Preparing 1000g of a solvent of 10 wt% of NaOH/5 wt% of urea/4.0 wt% of zinc oxide/81 wt% of water, pre-cooling the solvent to-8 ℃, adding 40 g of cellulose into the solvent, stirring at normal temperature, and completely dissolving the cellulose after 5 minutes. And (4) centrifuging for 5 minutes by using a centrifuge at 4000r/min for deaeration to obtain clear and transparent cellulose spinning solution.

Pouring the spinning solution into a sealed tank, immersing a spinning head into a coagulating bath consisting of 20 wt% of citric acid/20 wt% of sodium citrate/5 wt% of ethylene glycol/55 wt% of water, and controlling the extrusion rate of the spinning solution to be 6 m/min and the temperature of the coagulating bath to be 10 ℃. And (3) allowing the spinning solution to enter a coagulating bath, coagulating and forming into filaments, collecting the filaments by using a roller, drawing the filaments into a thermostatic bath filled with water of 60 ℃, and controlling the rotating speed ratio of the rollers at two ends of the thermostatic bath to be 1.8 to obtain the cellulose filaments with the drawing ratio of 1.8. And washing, drying and collecting coils to obtain the high-strength cellulose filaments.

The mechanical property of the silk is detected to reach 2.7cN/dtex (figure 2) through a tensile machine, which is higher than the reported strength (2.2cN/dtex) of the cellulose silk prepared by a viscose method.

Example 3

Preparing 1000g of a solvent of 8 wt% NaOH/15 wt% urea/5 wt% zinc oxide/72 wt% water, pre-cooling the solvent to-12 ℃, adding 100 g of cellulose into the solvent, stirring at normal temperature, and completely dissolving the cellulose after 5 minutes. And (4) centrifuging for 5 minutes by using a centrifuge at 4000r/min for deaeration to obtain clear and transparent cellulose spinning solution.

Pouring the spinning solution into a sealed tank, immersing a spinning head into a coagulating bath consisting of 5 wt% of citric acid/15 wt% of sodium citrate/30 wt% of ethylene glycol/50 wt% of water, and controlling the extrusion rate of the spinning solution to be 8 m/min and the temperature of the coagulating bath to be 20 ℃. And (3) allowing the spinning solution to enter a coagulating bath, coagulating and forming into filaments, collecting the filaments by using a roller, drawing the filaments into a thermostatic bath filled with 70 ℃ water, and controlling the rotating speed ratio of the rollers at two ends of the thermostatic bath to be 2.2 to obtain the cellulose filaments with the drawing ratio of 2.2. And washing, drying and collecting coils to obtain the high-strength cellulose filaments.

Example 4

Preparing 1000g of a solvent of 6 wt% of NaOH/11 wt% of urea/1.0 wt% of zinc oxide/82 wt% of water, pre-cooling the solvent to-12 ℃, adding 65 g of cellulose into the solvent, stirring at normal temperature, and completely dissolving the cellulose after 5 minutes. And (4) centrifuging for 5 minutes by using a centrifuge at 4000r/min for deaeration to obtain clear and transparent cellulose spinning solution.

Pouring the spinning solution into a sealed tank, immersing a spinning head into a coagulating bath consisting of 25 wt% of citric acid/5 wt% of sodium citrate/60 wt% of ethylene glycol/10 wt% of water, and controlling the extrusion rate of the spinning solution to be 10 m/min and the temperature of the coagulating bath to be 0 ℃. The spinning solution is coagulated and formed into filaments after entering a coagulating bath, the filaments are collected by a roller and then drawn into a thermostatic bath filled with water of 85 ℃, the ratio of the rotating speed of the roller at the two ends of the thermostatic bath is controlled to be 2.8, and the cellulose filaments with the drawing ratio of 2.8 are obtained. And washing, drying and collecting coils to obtain the high-strength cellulose filaments.

Example 5

Preparing 1000g of a solvent of 8 wt% of NaOH/10 wt% of urea/2.0 wt% of zinc oxide/80 wt% of water, pre-cooling the solvent to-15 ℃, adding 85 g of cellulose into the solvent, stirring at normal temperature, and completely dissolving the cellulose after 5 minutes. And (4) centrifuging for 5 minutes by using a centrifuge at 4000r/min for deaeration to obtain clear and transparent cellulose spinning solution.

Pouring the spinning solution into a sealed tank, immersing a spinning head into a coagulating bath consisting of 35 wt% of citric acid/20 wt% of sodium citrate/35 wt% of ethylene glycol/10 wt% of water, and controlling the extrusion rate of the spinning solution to be 10 m/min and the temperature of the coagulating bath to be 5 ℃. The spinning solution is coagulated and formed into filaments after entering a coagulating bath, the filaments are collected by a roller and then drawn into a thermostatic bath filled with water of 40 ℃, the ratio of the rotating speed of the roller at the two ends of the thermostatic bath is controlled to be 2.0, and the cellulose filaments with the drawing ratio of 2.0 are obtained. And washing, drying and collecting coils to obtain the high-strength cellulose filaments.

The results show that the method for preparing the high-strength cellulose filaments constructed based on the nano-fibers has the advantages of low cost, small pollution, short period, high efficiency and the like.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention.

Claims

1. A preparation method of high-strength cellulose filaments with low cost, green and high efficiency is characterized by comprising the following steps:

(1) dissolving high-quality-fraction solid cellulose by using a solvent prepared from alkali/urea/zinc oxide/water;

(2) preparing high-strength cellulose filaments constructed based on nano fibers by using a mixed solution of citric acid/sodium citrate/ethylene glycol/water as a coagulating bath through an extruder; the contents of citric acid, sodium citrate, ethylene glycol and water in the coagulating bath are respectively 5-35 wt%, 2-20 wt%, 5-60 wt% and 10-70 wt%;

(4) and then washing, oiling and drying to obtain the oil-water-based paint.

2. The method according to claim 1, wherein the viscosity-average molecular weight of the cellulose in the step (1) is less than 1.5 × 10⁵。

3. The method of claim 1, wherein: in the step (1), the solvent is pre-cooled to-20 to-8 ℃, then the cellulose is added, and the solvent can be completely dissolved after high-speed stirring.

4. The method according to claim 1 or 2, characterized in that: and (2) the alkali in the solvent in the step (1) is sodium hydroxide.

5. The method according to claim 1 or 2, characterized in that: in the step (1), the concentration of alkali in the solvent is 5-10 wt%, the concentration of urea is 5-20 wt%, the concentration of zinc oxide is 0.5-5 wt%, and the balance is water.

6. The method of claim 1, wherein: the temperature of the coagulation bath in the step (2) is 0-25 ℃.

7. The method of claim 1, wherein: and (3) the extrusion speed of the extruder in the step (2) is 3-10 m/min.

8. The method of claim 1, wherein: the temperature of the water bath in the step (3) is 40-85 ℃; the traction is two-stage traction, and the drafting rate is 1.2-2.8.

9. A low-cost, green, efficient high strength cellulose silk which characterized in that: prepared by the method of any one of claims 1 to 8.