Regenerated bamboo fiber and preparation method and application thereof

Abstract

This invention relates to the field of fiber regeneration technology, specifically to a regenerated bamboo fiber and its preparation method and application. The method includes: (1) degassing a bamboo cellulose carbamate solution to obtain a spinning solution; (2) extruding the spinning solution into a coagulation bath, forming it in the coagulation bath, and then washing and drying it to obtain regenerated bamboo fiber; the bamboo cellulose carbamate solution comprises, by weight, 6wt%–10wt% sodium hydroxide, 0.5wt%–6wt% urea, 84wt%–94wt% water, and 6wt%–9wt% bamboo cellulose carbamate; the nitrogen content of the bamboo cellulose carbamate is not higher than 1.0%.

Description

Technical Field

[0001] This invention relates to the field of fiber regeneration technology, specifically to a regenerated bamboo fiber, its preparation method, and its application. Background Technology

[0002] Plant cellulose, as the most abundant renewable natural polymer material on Earth, is found in large quantities in trees, cotton, bamboo, straw on land, and sea squirts and algae in the ocean. Due to its wide distribution, large reserves, renewable and biodegradable characteristics, fully utilizing cellulose resources can not only protect the ecological environment but also alleviate over-reliance on petroleum resources. However, each glucose ring in the cellulose macromolecule has three hydroxyl groups, which play a decisive role in reactions such as oxidation, esterification, etherification, and graft copolymerization. Because of the polyhydroxyl structure of cellulose, numerous hydrogen bonds exist both intramolecularly and intermolecularly. The presence of these hydrogen bonds results in a tightly packed molecular chain, forming highly ordered crystalline regions. This characteristic makes cellulose difficult to dissolve in common solvents and difficult to melt process. Therefore, using a green, inexpensive, and efficient solvent to dissolve cellulose is of great significance.

[0003] For a long time, the viscose process has dominated the production of regenerated cellulose filaments and films. However, the production process of viscose fiber is complicated and uses reagents such as zinc sulfate, sulfite, and sodium sulfide, which will generate a large amount of harmful gases such as carbon disulfide and hydrogen sulfide (J. Macromol. Sci-Rev. Macromol. Chem 1980, C18(1),1), which is seriously inconsistent with my country's current environmental protection policy. In addition, the commercially available solution system N-methylmorpholine-N-oxide (NMMO) is expensive and energy-intensive (see Chinese patent ZL97107819.X). In recent years, ionic liquids have emerged as a green system with good dissolving properties and good recycling performance (see CN1140422, CN 03116642.3, CN100572432C), but this system also has disadvantages such as the solution being gel-like and difficult to use for industrial spinning.

[0004] The cellulose carbamate process is a novel process for preparing regenerated cellulose fibers using cellulose carbamate (CC) as a raw material. The entire production process of the cellulose carbamate process is relatively environmentally friendly. However, the solubility of cellulose carbamate is affected by factors such as molecular weight, dissolution temperature, alkali concentration, and degree of esterification. Therefore, various methods for dissolving cellulose carbamate have been proposed, such as adding a certain amount of cellulose carbamate to a 10 wt% sodium hydroxide solution at -5°C and stirring continuously for 1–3 hours (see US Patent 4530999). Other researchers have immersed cellulose carbamate in a 1–2 wt% sodium hydroxide solution at 0°C, then poured a sodium hydroxide solution at approximately -20°C into the mixture, and stirred at -6°C (see WO 2007 / 060296A1). In addition, some scholars have proposed placing a certain amount of cellulose carbamate in an aqueous solution of 6-10 wt% sodium hydroxide and 0.1-3 wt% zinc oxide, stirring thoroughly, freezing at -10 to -20°C for 3-5 hours, and then thawing at room temperature (see CN102432894B). However, the above method has disadvantages such as excessive alkali usage, long processing time, or high cost of zinc oxide, which are not conducive to industrialization. Although sodium hydroxide is the cheapest reagent for dissolving cellulose carbamate, this solvent can only dissolve cellulose with low degree of polymerization (DP<400), and the solution is unstable and prone to gelation, resulting in poor strength of the subsequently obtained cellulose filaments (see US Patent 4634470). Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that the dissolution and regeneration process of bamboo cellulose carbamate in the prior art leads to low antibacterial ability or even loss of antibacterial ability in regenerated bamboo fiber. This invention provides a regenerated bamboo fiber, its preparation method, and its application. The regenerated bamboo fiber prepared by the present invention, obtained by wet spinning of bamboo fiber carbamate solution, has excellent antibacterial properties.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing regenerated bamboo fiber, the method comprising:

[0007] (1) The spinning solution of bamboo cellulose carbamate solution is defoamed to obtain the spinning solution;

[0008] (2) The spinning solution is spun into a coagulation bath, and after being formed in the coagulation bath, it is washed and dried to obtain recycled bamboo fiber.

[0009] Based on the total weight of the bamboo cellulose carbamate solution, the bamboo cellulose carbamate solution comprises:

[0010] 6wt%–10wt% sodium hydroxide, 0.5wt%–6wt% urea, 84wt%–94wt% water, 6wt%–9wt% bamboo cellulose carbamate;

[0011] The nitrogen content of the bamboo cellulose carbamate is not higher than 1.0%.

[0012] A second aspect of the present invention provides a regenerated bamboo fiber prepared by the method for preparing regenerated bamboo fiber described in the present invention.

[0013] A third aspect of the present invention provides the application of the regenerated bamboo fiber described herein in antibacterial materials.

[0014] Through the above technical solution, the method for preparing regenerated bamboo fiber of the present invention uses the bamboo fiber carbamate solution of the present invention to prepare regenerated bamboo fiber, which can retain the antibacterial activity of bamboo fiber itself and has high dry breaking strength. Attached Figure Description

[0015] Figure 1 XRD pattern of the regenerated fiber prepared in Example 1;

[0016] Figure 2 The graphs show the inhibition curves of regenerated bamboo fiber prepared in Example 1 and Comparative Example 2 against Escherichia coli. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] The first aspect of this invention provides a method for preparing regenerated bamboo fiber, the method comprising:

[0019] (1) The spinning solution of bamboo cellulose carbamate solution is defoamed to obtain the spinning solution;

[0020] (2) The spinning solution is spun into a coagulation bath, and after being formed in the coagulation bath, it is washed and dried to obtain recycled bamboo fiber.

[0021] Based on the total weight of the bamboo cellulose carbamate solution, the bamboo cellulose carbamate solution comprises:

[0022] 6wt%–10wt% sodium hydroxide, 0.5wt%–6wt% urea, 84wt%–94wt% water, 6wt%–9wt% bamboo cellulose carbamate;

[0023] The nitrogen content of the bamboo cellulose carbamate is not higher than 1.0%.

[0024] According to a preferred embodiment of the present invention, the bamboo cellulose carbamate has a molecular weight of 3.7-5W.

[0025] According to a preferred embodiment of the present invention, the nitrogen content of the bamboo cellulose carbamate is 0.6-1.0%, which is beneficial to further improve the antibacterial activity of regenerated bamboo fiber.

[0026] According to a preferred embodiment of the present invention, the bamboo cellulose carbamate solution comprises, by weight: 7 wt% to 8 wt% sodium hydroxide, 4 wt% to 6 wt% urea, 86 wt% to 89 wt% water, and 6 wt% to 9 wt% bamboo cellulose carbamate, which is beneficial to further improve the antibacterial activity of regenerated bamboo fiber.

[0027] According to a preferred embodiment of the present invention, the method for preparing the bamboo cellulose carbamate solution includes: cooling a solution containing 6wt% to 10wt% sodium hydroxide, 0.5wt% to 6wt% urea, and 84wt% to 94wt% water to -5 to -10°C; and dispersing the bamboo cellulose carbamate in the solution to obtain the bamboo cellulose carbamate solution.

[0028] According to a preferred embodiment of the present invention, the method for preparing the bamboo cellulose carbamate solution further includes: centrifuging the dispersed bamboo cellulose carbamate solution, preferably, the centrifugation conditions include: a rotation speed of 5000-8000 RPM; a time of 5-10 min; and a temperature of 5-10℃.

[0029] According to a preferred embodiment of the present invention, the coagulation bath contains 5-15 wt% sulfuric acid and 0-20 wt% sodium sulfate.

[0030] According to a preferred embodiment of the present invention, in step (2), the molding temperature is 3-25°C.

[0031] A fourth aspect of this invention provides regenerated bamboo fiber prepared by the preparation method described herein. The preparation method of this invention retains the antibacterial activity of the bamboo fiber itself, and the regenerated bamboo fiber possesses antibacterial capabilities and its dry breaking strength meets the standards for qualified products.

[0032] According to a preferred embodiment of the present invention, the regenerated bamboo fiber is type II cellulose.

[0033] According to a preferred embodiment of the present invention, the dry breaking strength of the regenerated bamboo fiber is 0.91-2.0 cN / dtex.

[0034] A third aspect of the present invention provides the application of the regenerated bamboo fiber described herein in antibacterial materials.

[0035] In this invention, the nitrogen content in bamboo cellulose carbamate refers to the degree of substitution after the reaction of cellulose with urea.

[0036] The present invention will be described in detail below through embodiments.

[0037] Dry breaking strength test method: The ends of the dried regenerated bamboo fiber filaments are drawn out, and several meters of surface filament are removed. The filaments are then introduced into the clamps of a yarn length measuring instrument via a tensioning device. A specified pre-tension load is applied, and 100 meters of filament are taken. The filaments are cut at the junction of the ends, spun into strands, and placed in a sample tray. The sample is weighed at standard atmospheric pressure, accurate to 1 mg. A sample of a certain length is taken, one end is pressed down with a pressure plate, and the other end is loosened with a needle. The number of monofilaments in the sample is counted. The monofilament linear density is obtained by dividing the measured multifilament linear density by the number of monofilaments in the multifilament.

[0038] Insert one end of the wire into the jaws of one of the clamps and clamp it, keeping it in a slightly slack state. Ensure the wire is centered in the jaws of the clamp. Then tighten the clamp and you can begin testing the dry breaking strength.

[0039] Example 1

[0040] (1) Take 28 grams of bamboo cellulose carbamate (nitrogen content of 0.8% and molecular weight of 40,000) and add it to 322 grams of mixed aqueous solution containing 6wt% sodium hydroxide and 6wt% urea at a temperature of -10℃. Stir for 5 minutes to obtain an 8wt% light yellow solution. Centrifuge at 8000 RPM and 10℃ for 10 minutes using a high-speed centrifuge to obtain a transparent cellulose carbamate solution.

[0041] (2) In the storage tank of the cellulose carbamate solution obtained in step (1), the air is extracted by vacuum pump and the bubbles are removed to obtain the spinning solution.

[0042] (3) The spinning solution is extruded through the spinneret under the drive of the metering pump and formed in the coagulation bath; wherein the metering pump pressure is 0.8MPa, the spinneret is 50μm*500 holes, the coagulation bath composition is 8wt% sulfuric acid, 15wt% sodium sulfate, the remainder is water, and the coagulation bath temperature is 5℃.

[0043] The formed filament bundles are drawn out by the solidification rollers, washed with water, and dried at 85°C to obtain recycled bamboo fiber. The dry breaking strength of the recycled bamboo fiber is 1.21 cN / dtex.

[0044] Test method for antibacterial ability of test samples:

[0045] 1. Inoculate Escherichia coli into 50 mL of LB medium and incubate at 37°C for 12 h in a constant temperature shaker to obtain a bacterial suspension;

[0046] 2. The regenerated bamboo fibers from Examples 1-4 and Comparative Examples 1-2 were added to LB medium to prepare a solution with a regenerated fiber concentration of 2 wt%, and the sample to be tested was obtained.

[0047] 3. Take 50 μL of Escherichia coli suspension and add 0.4 g of the test sample to 20 mL of LB medium. Set up a control group and incubate in a constant temperature shaker at 37 °C for 210 r / min.

[0048] 4. Take samples every 0.5 hours and use an enzyme-linked immunosorbent assay (ELISA) reader to detect the concentration of E. coli at OD600nm.

[0049] Figure 1 The XRD pattern of the regenerated fiber prepared in Example 1 shows that the bamboo cellulose carbamates are all cellulose type I peaks, while the regenerated cellulose transforms into cellulose type II peaks after dissolution and regeneration.

[0050] Figure 2 The graphs show the inhibition curves of regenerated bamboo fiber against Escherichia coli prepared in Example 1 and Comparative Example 2, indicating that the regenerated bamboo fiber inhibits Escherichia coli by more than 90%.

[0051] Example 2

[0052] Take 21 grams of bamboo cellulose carbamate (nitrogen content of 1%, molecular weight of 38,000) and quickly add it to 329 grams of a mixed aqueous solution containing 7 wt% sodium hydroxide and 4 wt% urea at a temperature of -10℃. Stir for 5 minutes to obtain a light yellow solution. Centrifuge at 8000 RPM and 10℃ for 10 minutes using a high-speed centrifuge to obtain a transparent cellulose carbamate solution.

[0053] Steps (2) and (3) are the same as in Example 1.

[0054] The dry breaking strength of regenerated bamboo fiber is 2.0 cN / dtex.

[0055] Regenerated bamboo fiber inhibits Escherichia coli by more than 90%.

[0056] Example 3

[0057] Take 31.5 g of bamboo cellulose carbamate (nitrogen content of 0.6%) and quickly add it to 318.5 g of a 10 wt% sodium hydroxide / 6 wt% urea mixed aqueous solution at -10℃. Stir thoroughly for about 5 minutes to obtain a light yellow cellulose carbamate solution. Centrifuge at 8000 RPM and 10℃ for 10 minutes using a high-speed centrifuge to obtain a transparent cellulose carbamate solution.

[0058] Steps (2) and (3) are the same as in Example 1.

[0059] The dry breaking strength of recycled bamboo fiber is 1.73 cN / dtex.

[0060] Regenerated bamboo fiber inhibits Escherichia coli by 85-87%.

[0061] Example 4

[0062] The method is the same as in Example 1, except that the urea concentration in the mixed aqueous solution is 3 wt%, and the other conditions are the same as in Example 1.

[0063] The dry breaking strength of regenerated bamboo fiber is 0.99 cN / dtex.

[0064] Regenerated bamboo fiber inhibits Escherichia coli by 86-87%.

[0065] Comparative Example 1

[0066] Take 28 grams of bamboo cellulose carbamate (nitrogen content of 0.8%) and quickly add it to 322 grams of 8wt% sodium hydroxide aqueous solution at -10℃. Stir for 5 minutes to obtain a light yellow solution. Centrifuge at 8000 RPM and 10℃ for 10 minutes using a high-speed centrifuge to obtain a transparent cellulose carbamate solution.

[0067] The remaining conditions are the same as in Example 1.

[0068] The dry breaking strength of recycled bamboo fiber is 0.97 cN / dtex.

[0069] Regenerated bamboo fiber inhibits Escherichia coli by 25-30%.

[0070] Comparative Example 2

[0071] The method of Example 1 is the same, except that the nitrogen content of the bamboo cellulose carbamate is 1.2%; the other conditions are the same as in Example 1.

[0072] The dry breaking strength of recycled bamboo fiber is 1.30 cN / dtex.

[0073] Regenerated bamboo fiber inhibits Escherichia coli by 50-57%.

[0074] Comparative Example 3

[0075] (1) Cellulose carbamate (nitrogen content of 2.089%) was dissolved in a 7wt% NaOH / 1.6wt% ZnO aqueous solution by freezing and thawing. After filtration and degassing, it was used for wet spinning. The remaining conditions were the same as in Example 1. The resulting regenerated cellulose fiber had no antibacterial activity.

[0076] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing recycled bamboo fiber, characterized in that, The method includes: (1) The spinning solution of bamboo cellulose carbamate solution was defoamed to obtain the spinning solution; (2) The spinning solution is spun into a coagulation bath, and after being formed in the coagulation bath, it is washed and dried to obtain recycled bamboo fiber. Based on the total weight of the bamboo cellulose carbamate solution, the bamboo cellulose carbamate solution comprises: 6wt%~10wt% sodium hydroxide, 0.5wt%~6wt% urea, 84wt%-94wt% water, 6wt%~9wt% bamboo cellulose carbamate; The nitrogen content of the bamboo cellulose carbamate is not higher than 1.0%.

2. The preparation method according to claim 1, wherein, The bamboo cellulose carbamate has a molecular weight of 3.7-5W; and / or The nitrogen content of the bamboo cellulose carbamate is 0.6-1.0%; and / or The bamboo fiber carbamate has characteristic peaks of type I cellulose.

3. The preparation method according to claim 1, wherein, The solution comprises: 7wt%~8wt% sodium hydroxide, 4wt%~6wt% urea, 86wt%~89wt% water, and 6wt%~9wt% bamboo cellulose carbamate.

4. The preparation method according to any one of claims 1-3, wherein, The method for preparing the bamboo cellulose carbamate solution includes: The solution containing 6wt%~10wt% sodium hydroxide, 0.5wt%~6wt% urea, and 84wt%-94wt% water is cooled to -5-10℃; the bamboo cellulose carbamate is dispersed into the solution to obtain a bamboo cellulose carbamate solution.

5. The preparation method according to claim 4, wherein, The method for preparing the bamboo cellulose carbamate solution further includes centrifuging the dispersed bamboo cellulose carbamate solution.

6. The preparation method according to claim 5, wherein, Centrifugation conditions include: rotation speed of 5000-8000 RPM; time of 5-10 min; and temperature of 5-10℃.

7. The preparation method according to claim 1, wherein, The coagulation bath contains 5-15 wt% sulfuric acid and 0-20 wt% sodium sulfate.

8. The preparation method according to claim 1, wherein, In step (2), the molding temperature is 3-25℃.

9. Regenerated bamboo fiber prepared by the preparation method according to any one of claims 1-8.

10. The regenerated bamboo fiber according to claim 9, wherein, The regenerated bamboo fiber is type II cellulose; and / or The dry breaking strength of the regenerated bamboo fiber is 0.91-2.0 cN / dtex.

11. The use of the regenerated fiber as described in claim 9 or 10 in antibacterial materials.

Images