A method for preparing high fibrillated lyocell fibers from waste rubber hemicellulose

Abstract

The application discloses a method for preparing high fibrillation lyocell fibers from waste glue hemicellulose, and specifically comprises the following steps: waste glue liquid from filter backwashing is soaked in soft water to make cellulose coagulate and precipitate, NMMO solvent is washed out to be recycled and reused, and the washed waste cellulose is crushed and then mixed to prepare pulp; in the premixing stage, a separating agent material is uniformly added into the premixed pulp, and then heating, pressure reduction, evaporation and dehydration are carried out to obtain spinning dope with a cellulose concentration of 7-16 wt%; the spinning dope is extruded from a spinneret, immersed in an air bath, and then immersed in a coagulation bath containing NMMO aqueous solution to be coagulated and formed into nascent fiber bundles; and the nascent fiber bundles are subjected to drafting, washing, cutting, washing, oiling and drying to obtain high fibrillation lyocell fibers. The application realizes recycling of waste glue generated in the production process of the lyocell fiber industry, and to some extent, reduces the problems of high energy consumption and long time in the preparation of high fibrillation lyocell fibers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of regenerated cellulose preparation, in particular to a method for preparing high fibrillation lyocell fibers from waste glue hemicellulose. BACKGROUND

[0002] Lyocell fibers have the advantages of polyester-like strength, cotton comfort, viscose drape, silk-like luster, etc. It can design various high-end textiles, and is deeply loved by textile brand merchants and consumers.

[0003] Because a large amount of waste glue is produced in the lyocell production process, which mainly comes from the backwashing process of the glue liquid filtering device and the discharge link of the spinning head. Direct reuse of waste glue will cause impurities to accumulate in the system, affecting the quality of the fibers. At present, the disposal method is to send it to the garbage incineration plant for disposal, which not only cannot utilize the resource, but also needs to pay additional disposal fees.

[0004] The existing technical means has the problems of high energy consumption, long time, complex process, and high cost in preparing high fibrillation lyocell fibers. For example, the patent with application number US5725821 describes a cellulose fiber with enhanced fibrillation ability, which is obtained by spinning of a cellulose solution, wherein the degree of polymerization of the cellulose is not more than 450 and the concentration of the cellulose in the spinning solution is at least 16%. The disadvantage of this method is the use of more expensive low-polymerization cellulose and high cellulose concentration, which results in a very high viscosity of the spinning material, which greatly increases the difficulty of glue liquid transportation, filtration and spinning.

[0005] The patent with application number S6042769 also describes a cellulose fiber with enhanced fibrillation ability, wherein the fiber is subjected to bleaching conditions that result in a strong degree of polymerization reduction. High concentrations of hydrogen peroxide or sodium hypochlorite and subsequent evaporation treatment are used. The disadvantage of this method is that, in addition to the expected improvement in fibrillation behavior, the strength and elongation are significantly reduced (up to 50%).

[0006] The patent with application number US8187422 describes that lyocell staple fibers can be fibrillated using a disc refiner or similar device in an aqueous medium with low solids content. Such fibers are usually chemically pretreated to fibrillate the fibers, and without any chemical pretreatment, a large amount of energy and time will be consumed. SUMMARY

[0007] The present application aims to provide a method for preparing high fibrillation lyocell fibers from waste glue hemicellulose, which soaks the waste glue liquid from filter machine backwashing with soft water to precipitate the coagulated cellulose, washes and recycles the NMMO solvent, and then crushes the washed waste cellulose to mix and prepare pulp, glue liquid and spinning to solve the defects of long processing time, great influence on fiber product quality and high cost in the prior art.

[0008] To solve the above technical problems, the present application provides the following technical solutions:

[0009] A method for preparing high fibrillation lyocell fibers from waste glue hemicellulose, comprising the following steps:

[0010] S1, soaking the waste glue from filter machine backwashing with soft water to wash out the solvent and precipitate the waste cellulose, and crushing the precipitated waste cellulose;

[0011] S2, adding the crushed waste cellulose to the premix in the premixing stage, and obtaining the premixed pulp after stirring and dispersing for 40-60 minutes at a temperature of 70-100℃; the premix comprises cellulose pulp, NMMO aqueous solution, hydroxylamine and propyl gallate;

[0012] S3, adding the separating agent material uniformly to the premixed pulp in the premixing stage, and obtaining the spinning dope with a cellulose concentration of 7-16wt% after heating and reducing pressure evaporation;

[0013] S4, extruding the spinning dope from the spinneret, and obtaining the primary fiber bundle after coagulation and shaping in the coagulation bath containing NMMO aqueous solution through air bath, and then obtaining the high fibrillation lyocell fiber after drawing, washing, cutting, washing, oiling and drying.

[0014] Because the waste glue cellulose exists in the solvent for a long time, the cellulose is degraded, the molecular chain is shortened, the molecular weight and the degree of polymerization are reduced, and the small molecule hemicellulose (type B cellulose and type C cellulose) is obtained. These small molecule hemicelluloses are added to the premix in a certain proportion for reproduction and finally regenerated into lyocell fibers, which uniformly increases a lot of small molecule cellulose in the macromolecular chain of lyocell fibers, and plays the role of plasticizer and wetting agent in the whole fiber matrix. These small molecule chains of cellulose are more easily split into microfibrils along the fiber axis under the action of the separating agent uniformly distributed in the fiber through the addition of the original solution, thereby giving the lyocell fiber the characteristics of high fibrillation. The presence of the separating agent destroys the hydrogen bonds between the lyocell cellulose matrix molecules, making the fibrillation degree more obvious and violent.

[0015] Preferably, the ratio of the waste cellulose added in step S2 accounts for 0.5-20% of the total pulp cellulose added amount, the particle size of the waste cellulose is 0.1-5mm, and the waste cellulose added amount is preferably 1-10%; the total pulp cellulose added amount is the sum of the waste cellulose and the cellulose in the premix.

[0016] Preferably, the concentration of the NMMO aqueous solution in the premix in step S2 is 65±5%, and the mass ratio of the cellulose pulp and the NMMO aqueous solution is 1:(10-15).

[0017] Preferably, the cellulose pulp includes but is not limited to one or a combination of wood pulp, bamboo pulp, hemp pulp, grass pulp, and cotton pulp.

[0018] Preferably, the separating agent material includes but is not limited to one or a combination of mica powder, titanium dioxide powder, ammonium chloride, mineral oil, cellulose acetate, and enzyme.

[0019] Preferably, the added amount of the separating agent material is 0.1-10% of the total cellulose mass in the premixed pulp, and the particle size of the separating agent material is ≤1μm.

[0020] Preferably, the dehydration time in step S3 is 10-180 minutes, the dehydration vacuum degree is -0.095~-0.1MPa, and the dehydration temperature is 90-120℃.

[0021] Preferably, the spinning speed during the production of the primary fiber bundle in step S4 is 20-60m / min, and the spinning temperature is 90-110℃.

[0022] Preferably, the NMMO concentration in the coagulation bath in step S4 is 10-25%.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] 1. The present application solves the problem of waste glue produced during the production of lyocell fibers by recycling the large amount of waste glue produced during the production of lyocell, thereby improving resource utilization and increasing economic benefits.

[0025] 2, the waste rubber hemicellulose participates in production into the glue liquid system again, because its molecular chain is short, the molecular weight is small, the degree of polymerization is low, thereby effectively reducing the viscosity of the glue liquid, these small molecule hemicelluloses are added into the pulp and pulp premix in a certain proportion to produce again and finally to produce lyocell fiber again, which makes the lyocell fiber macromolecular chain uniformly increase a lot of small molecule cellulose, which plays the role of plasticizer and wetting agent in the whole fiber matrix. These small molecule chain cellulose is more prone to split into microfibrils along the fiber axis under the action of friction, kneading and bending during the use of lyocell fiber textiles, and the separation agent uniformly distributed in the fiber through the original liquid adding means, thereby giving lyocell fiber high fibrillation characteristics. It is beneficial to improve the delivery, filtration and spinnability of the spinning dope in production.

[0026] 3, the lyocell fiber obtained by the method has high fibrillation degree, the microfibrillation is combined closely with the main fiber, the strength is high, and the hair is not easy to fall off, so that the lyocell fiber can be widely used in the fields of filtration, covering fabric, anti-penetration feather fabric, battery separator and absorbent pad. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, which together with the embodiments of the application, are used to explain the application, and do not constitute a limitation on the application. In the drawings:

[0028] Figure 1 is a step flow chart of a method for preparing high fibrillation lyocell fiber from waste rubber hemicellulose. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0030] Example 1

[0031] 1) The waste rubber from backwashing of the filter is first soaked in soft water to wash out the solvent, and then the cellulose precipitated and condensed from the water is crushed to 0.1-5mm debris.

[0032] 2) The crushed waste cellulose is added to the premix consisting of cellulose pulp, NMMO aqueous solution, hydroxylamine and propyl gallate in the premixing stage, and after 50 minutes at a temperature of 80℃, the premixed porridge is obtained.

[0033] The waste cellulose is added in a proportion of 15% of the total cellulose pulp added in the premixing process.

[0034] The NMMO aqueous solution in the premix has a concentration of 65±5%, the mass ratio of cellulose pulp to NMMO solution is 1:(10-15), and the amounts of hydroxylamine and propyl gallate added are 1‰ and 1.2‰ of the total cellulose mass in the premixed pulp.

[0035] 3) In the premixing stage, mica powder with a particle size of 95% of 0.8 μm is uniformly added in an amount of 8% of the total cellulose mass in the premixed pulp. The premixed pulp is heated and dehydrated under reduced pressure to produce a spinning dope with a cellulose concentration of 7-16 wt%. The dehydration temperature is 100°C, the vacuum degree is -0.098 MPa, and the time is 140 minutes.

[0036] 4) The spinning dope is extruded from the spinneret, immersed in a coagulation bath containing an NMMO aqueous solution with a concentration of 18% to coagulate and form a nascent fiber bundle, and then drawn, washed, cut, washed, oiled, and dried to obtain high fibrillation lyocell fibers with a fineness of 1.34 dtex, a dry breaking strength of 3.89 CN / dtex, a dry elongation of 15.51%, and a fibrillation index of 9.87. The high fibrillation lyocell fibers obtained have good spinnability.

[0037] In the production process of the nascent fiber bundle, the spinning speed is 30 m / min, and the spinning temperature is 98°C.

[0038] Example 2

[0039] 1) The waste glue from the backwashing of the filter is first soaked in soft water to wash out the solvent, and then the cellulose precipitated from the water is crushed to 0.1-5 mm of debris.

[0040] 2) The crushed waste cellulose is added to the premix consisting of cellulose pulp, NMMO aqueous solution, hydroxylamine, and propyl gallate in the premixing stage. After 50 minutes at a temperature of 80°C, a premixed pulp is obtained.

[0041] The waste glue half-fiber is added in an amount of 10 wt% of the total cellulose pulp added; the total cellulose pulp added is the sum of the waste cellulose and the cellulose in the premix

[0042] The NMMO aqueous solution in the premix has a concentration of 65±5%, the mass ratio of cellulose pulp to NMMO solution is 1:(10-15), and the amounts of hydroxylamine and propyl gallate added are 1‰ and 1.2‰ of the total cellulose mass in the premixed pulp.

[0043] 3) In the premixing stage, the uniform addition of the titanium dioxide powder, the addition amount of the separating agent titanium dioxide powder is 5% of the total mass of the premixed pulp. The premixed pulp is heated and evaporated under reduced pressure to remove water, and a spinning dope with a cellulose concentration of 7-16 wt% is prepared. The temperature during dehydration is 100°C, the pressure is -0.098 MPa, and the time is 140 minutes.

[0044] 4) The spinning dope is extruded from the spinneret, immersed in the coagulation bath containing the aqueous solution of NMMO with a concentration of 18% through the air bath, and coagulated and formed into a nascent fiber bundle. After drawing, washing, cutting, washing, oiling, and drying, a high fibrillation lyocell fiber with a fineness of 1.32 dtex, a dry breaking strength of 4.01 CN / dtex, a dry elongation of 14.77%, and a fibrillation index of 8.32 is obtained. The high fibrillation lyocell fiber obtained has good spinnability.

[0045] Example 3

[0046] 1) The waste rubber from the backwashing of the filter is first soaked in soft water to wash out the solvent, and then the cellulose precipitated from the water is crushed to 0.1-5 mm of debris.

[0047] 2) The crushed waste cellulose is added to the premix consisting of cellulose pulp, NMMO aqueous solution, hydroxylamine, and propyl gallate in the premixing stage. After 50 minutes at a temperature of 80°C, a premixed pulp is obtained.

[0048] The addition amount of the waste rubber semi-fiber is 5 wt% of the total cellulose pulp fiber addition amount; the total cellulose pulp fiber addition amount is the sum of the waste cellulose and the cellulose in the premix

[0049] The NMMO aqueous solution in the premix has a concentration of 65±5%, the mass ratio of cellulose pulp to NMMO solution is 1:(10-15), and the addition amount of hydroxylamine and propyl gallate is 1‰ and 1.2‰ of the total cellulose mass of the premixed pulp.

[0050] 3) In the premixing stage, the uniform addition of the titanium dioxide powder, the addition amount of the separating agent titanium dioxide powder is 5% of the total mass of the premixed pulp. The premixed pulp is heated and evaporated under reduced pressure to remove water, and a spinning dope with a cellulose concentration of 7-16 wt% is prepared. The temperature during dehydration is 100°C, the pressure is -0.098 MPa, and the time is 140 minutes.

[0051] 4) The dope solution is extruded from the spinneret, immersed in the coagulation bath containing 18% NMMO aqueous solution through air bath, and coagulated to form nascent fiber bundle, then drawn, washed, cut, washed, oiled and dried to obtain high fibrillation lyocell fiber with 1.33 dtex, 4.16 CN / dtex of dry breaking strength, 14.03% of dry elongation and 7.89 of fibrillation index. The high fibrillation lyocell fiber obtained has good spinnability.

[0052] It can be seen from the comparative examples 1, 2 and 3 that, with the increase of the amount of waste rubber cellulose (hemicellulose) and separating agent, the amorphous region in the fiber also increases. When the cellulose absorbs a large amount of water and swells, part of the hydrogen bonds are destroyed by the separating agent, making the transverse binding force weaker. Combined with continuous friction and bending effect, the skin layer fiber is easily peeled off, making the fibrillation index of the fiber significantly increase, the dry strength decrease and the elongation increase.

[0053] It should be noted that the relational terms herein such as first and second, and the like, are used solely to distinguish one from another entity or action, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0054] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will still be able to modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose, characterized in that, The steps include: S1. Soak the waste glue from the backwashing device of the glue solution during the production process of Lyocell in soft water to wash out the solvent, so that the waste cellulose coagulates and precipitates out, and then crushes the coagulated and precipitated waste cellulose. S2. The pulverized waste cellulose is added to the premix during the premixing stage. After stirring and dispersing at a temperature of 70-100℃ for 40-60 minutes, a premixed pulp is obtained. The premix includes cellulose pulp, NMMO aqueous solution, hydroxylamine, and propyl gallate. The proportion of waste cellulose added accounts for 0.5-20% of the total pulp cellulose addition, and the pulverized particle size is 0.1-5mm. The total pulp cellulose addition amount is the sum of waste cellulose and cellulose in the premix; S3. In the premixing stage, the separating agent material is uniformly added to the premixed slurry and then heated and dehydrated by vacuum evaporation to obtain a spinning solution with a cellulose concentration of 7-16 wt%; the separating agent material is one or a combination of mica powder, titanium dioxide powder, and cellulose acetate. S4. The spinning solution is extruded from the spinneret, and after passing through an air bath, it is immersed in a coagulation bath containing an aqueous solution of NMMO to solidify and form a nascent fiber bundle. Then, it is drawn, washed, cut, washed again, oiled, and dried to obtain high-altitude fiberized lyocell fiber.

2. The method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose according to claim 1, characterized in that, In step S2, the concentration of the NMMO aqueous solution in the premix is ​​65±5%, and the mass ratio of the cellulose pulp to the NMMO aqueous solution is 1:(10-15).

3. The method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose according to claim 1, characterized in that, The cellulose pulp is one or a combination of several of the following: wood pulp, bamboo pulp, hemp pulp, straw pulp, and cotton pulp.

4. The method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose according to claim 1, characterized in that, The amount of the separating agent material added is 0.1-10% of the total cellulose mass in the premixed porridge, and the particle size of the separating agent material is ≤1μm.

5. The method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose according to claim 1, characterized in that, The dehydration time in step S3 is 10-180 minutes, the dehydration vacuum degree is -0.095 to -0.1 MPa, and the dehydration temperature is 90-120℃.

6. The method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose according to claim 1, characterized in that, In step S4, the spinning speed during the production of the nascent fiber bundle is 20-60 m / min, and the spinning temperature is 90-110℃.

7. The method for preparing highland-fiberized lyocell fiber from waste gum hemicellulose according to claim 1, characterized in that, The NMMO concentration in the coagulation bath in step S4 is 10-25%.

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