Method for preparing plateau fibrillated lyocell fiber from waste rubber hemicellulose

Abstract

The invention discloses a method for preparing plateau fibrillated lyocell fibers by using waste rubber hemicellulose, which comprises the following specific steps: soaking waste rubber liquid backwashed by a filter with soft water to solidify and separate out cellulose, washing out by using an NMMO (N-methylmorpholine-N-oxide) solvent, recycling and reusing, crushing the washed waste cellulose, and mixing to prepare porridge; in the premixing stage, a separating agent material is uniformly added into premixed slurry porridge, and then heating, reduced-pressure evaporation and dehydration are performed to obtain a spinning solution with the cellulose concentration of 7-16 wt%; the preparation method comprises the following steps: extruding a spinning solution from a spinneret plate, carrying out air bath, immersing into a coagulating bath containing an NMMO (N-methylmorpholine-N-oxide) aqueous solution, coagulating and forming to obtain a nascent fiber bundle, and drafting, washing, cutting, washing, oiling and drying to obtain the plateau fibrillated lyocell fiber. According to the method, the waste rubber generated in the production process of the Lyocell fiber industry is recycled, and the problems of high energy consumption and long time during preparation of plateau fibrillated Lyocell fibers are reduced to a certain extent.

Description

Technical Field

[0001] The invention relates to the technical field of regenerated cellulose preparation, in particular to a method for preparing high-density fibrillated lyocell fibers from waste rubber hemicellulose. Background Art

[0002] Lyocell fiber has the advantages of polyester-like strength, cotton-like comfort, viscose fiber's drape, and silk-like luster. It can be used to design a variety of high-end textiles and is deeply loved by textile brands and consumers.

[0003] A large amount of waste rubber is generated during the production of lyocell, mainly from the backwashing process of the rubber filtration device and the discharge process of the spinning head. Directly reusing the waste rubber will cause impurities to accumulate in the system, affecting the fiber quality. The current disposal method is mostly to send it to a waste incineration plant for disposal, which not only fails to utilize the resource, but also requires additional processing costs.

[0004] The existing technical means have 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 a cellulose solution, wherein the degree of polymerization of the cellulose is not more than 450 and the cellulose concentration in the spinning solution is at least 16%. The disadvantage of this method is that more expensive low-polymer cellulose and high cellulose concentration are used, which leads to a very high viscosity of the spinning material, which greatly increases the difficulty of glue delivery, filtration and spinning.

[0005] Patent No. S6042769 also describes a cellulose fiber with enhanced fibrillation capacity, in which the fiber is subjected to bleaching conditions that lead to a strong reduction in the degree of polymerization. High concentrations of hydrogen peroxide or sodium hypochlorite and subsequent evaporation are used. The disadvantage of this method is that, in addition to the expected improvement in fibrillation behavior, strength and elongation are significantly reduced (up to 50%).

[0006] Application number is US8187422 patent describes that lyocell staple fiber can use disc refiner or similar equipment in aqueous medium with low solid content fibrillation. Usually such fiber is chemically pretreated to fibrillate the fiber, if there is no chemical pretreatment, will consume a lot of energy and time. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing high-altitude fibrillated lyocell fiber from waste rubber hemicellulose. The invention soaks the waste rubber liquid backwashed from the filter with soft water to precipitate the coagulated cellulose, washes it out with NMMO solvent, recovers it and recycles it, and then grinds the washed waste cellulose and mixes it with pulping porridge, rubber liquid and spinning to solve the defects of the prior art means proposed in the above background technology, such as long processing time, great impact on the quality of fiber products and high cost.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] A method for preparing high-altitude fibrillated lyocell fiber from waste rubber hemicellulose, the steps comprising:

[0010] S1. Soak the waste rubber backwashed from the filter in soft water to remove the solvent, so that the waste cellulose is coagulated and precipitated, and the coagulated and precipitated waste cellulose is crushed;

[0011] S2, the crushed waste cellulose is added to the premix in the premixing stage, and the premixed porridge is obtained after stirring and dispersing at a temperature of 70-100° C. for 40-60 minutes; the premix includes cellulose pulp, NMMO aqueous solution, hydroxylamine, and propyl gallate;

[0012] S3, in the premixing stage, the separating agent material is evenly added to the premixed porridge, and then heated and decompressed to evaporate and dehydrate, so as to obtain a spinning solution with a cellulose concentration of 7 to 16 wt%;

[0013] S4, the spinning solution is squeezed out from the spinneret, and then immersed in a coagulation bath containing an aqueous solution of NMMO to coagulate and form, so as to obtain a primary fiber bundle, and then the primary fiber bundle is drawn, washed, cut, washed, oiled and dried to obtain high-density lyocell fiber.

[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 2 cellulose and type 3 cellulose) is formed. These small molecule hemicelluloses are added to the premix in a certain proportion for reproduction and finally regenerated into lyocell fiber, which makes a lot of small molecule celluloses evenly added to the macromolecular chain of lyocell fiber, and it plays the role of plasticizer and wetting agent in the whole fiber matrix. The cellulose of these small molecule chains is more likely to split microfibrils along the fiber axis with the friction, rubbing, bending effect of lyocell fiber textiles during use and the support of the separator uniformly distributed in the fiber by the means of adding the stock solution, thereby giving the lyocell fiber the characteristic of high plateau fibrillation. The presence of the separator destroys the hydrogen bonds between the molecules of the lyocell cellulose matrix, making its fibrillation degree more obvious and intense.

[0015] Preferably, in step S2, the proportion of waste cellulose added accounts for 0.5-20% of the total pulp cellulose added, the crushed particle size is 0.1-5 mm, and the amount of waste cellulose added is preferably 1-10%; the total pulp cellulose added 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 to 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, straw 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 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 ≤1 μm.

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

[0021] Preferably, 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°C.

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

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0024] 1. The present invention solves the problem of treating waste rubber generated in the production process of lyocell fibers by recycling a large amount of waste rubber generated in the production process of lyocell fibers, thereby improving resource utilization and increasing economic benefits.

[0025] 2. Waste rubber hemicellulose participates in production again and enters the glue liquid system. Due to its short molecular chain, small molecular weight and low degree of polymerization, the viscosity of the glue liquid is effectively reduced. These small molecular hemicelluloses are added to the pulp premix in a certain proportion for reproduction and finally regenerated into lyocell fiber, which makes a lot of small molecular cellulose evenly added to the macromolecular chain of lyocell fiber, which plays the role of plasticizer and wetting agent in the whole fiber matrix. These small molecular chain celluloses are more likely to split into microfibrils along the fiber axis with the friction, rubbing and bending of lyocell fiber textiles during use, and with the help of the separator evenly distributed in the fiber by adding the stock solution, thus giving the lyocell fiber the characteristics of high plateau fibrillation. It is beneficial to the transportation, filtration and spinnability of the spinning stock solution in production.

[0026] 3. The lyocell fiber obtained by the present invention has a high degree of fibrillation, the microfibrillation is closely combined with the main fiber, the strength is high, and it does not shed hair. It can be widely used in the fields of filtration, covering fabrics, anti-feather penetration fabrics, battery separators and absorbent pads. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 The present invention is a flow chart of the steps of a method for preparing high-density fibrillated lyocell fiber from waste rubber hemicellulose. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] 1) Soak the waste rubber backwashed from the filter in soft water to remove the solvent, and then crush the cellulose that has coagulated and precipitated into 0.1-5mm fragments.

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

[0033] The proportion of waste cellulose added is 15% of the total pulp cellulose added in the premix. The total pulp cellulose added is the sum of waste cellulose and cellulose in the premix.

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

[0035] 3) In the premixing stage, mica powder with a DN95% particle size of 0.8 μm is uniformly added in an amount of 8% of the total cellulose mass in the premixed slurry. The premixed slurry is heated and decompressed to evaporate and dehydrate to obtain a spinning solution with a cellulose concentration of 7 to 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 solution is squeezed out from the spinneret, and then immersed in a coagulation bath containing an aqueous solution with a concentration of 18% NMMO to coagulate and form a primary fiber bundle, which is then drawn, washed, cut, washed, oiled and dried to obtain a high-density fibrillated Lyocell fiber 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 obtained high-density fibrillated Lyocell fiber has excellent spinnability.

[0037] The spinning speed during the production of the nascent fiber bundle is 30 m / min, the spinning temperature is 98° C., and the coagulation bath temperature is 20° C.

[0038] Example 2

[0039] 1) Soak the waste rubber backwashed from the filter in soft water to remove the solvent, and then crush the cellulose that has coagulated and precipitated into 0.1-5mm fragments.

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

[0041] The amount of waste rubber hemicellulose added is 10wt% of the total pulp cellulose added; the total pulp cellulose added is the sum of the waste cellulose and the cellulose in the premix.

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

[0043] 3) In the premixing stage, titanium dioxide powder is uniformly added, and the amount of titanium dioxide powder added as a separating agent is 5% of the total mass of the premixed slurry. The premixed slurry is heated and decompressed to evaporate and dehydrate, and a spinning solution with a cellulose concentration of 7 to 16 wt% is obtained. The dehydration temperature is 100° C., the pressure is -0.098 MPa, and the time is 140 minutes.

[0044] 4) The spinning solution is squeezed out from the spinneret, and then immersed in a coagulation bath containing an aqueous solution with a concentration of 18% NMMO to coagulate and form a primary fiber bundle, which is then drawn, washed, cut, washed, oiled and dried to obtain a high-density fibrillated 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. The obtained high-density fibrillated Lyocell fiber has good spinnability.

[0045] Example 3

[0046] 1) Soak the waste rubber backwashed from the filter in soft water to remove the solvent, and then crush the cellulose that has coagulated and precipitated into 0.1-5mm fragments.

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

[0048] The amount of waste rubber hemicellulose added is 5wt% of the total pulp cellulose added; the total pulp cellulose added is the sum of the waste cellulose and the cellulose in the premix.

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

[0050] 3) In the premixing stage, cellulose acetate with a DN95% particle size of 0.8 μm is uniformly added in an amount of 1% of the total cellulose mass in the premixed slurry. The premixed slurry is heated and decompressed to evaporate and dehydrate to obtain a spinning solution with a cellulose concentration of 7 to 16 wt%. The dehydration temperature is 100°C, the vacuum degree is -0.098 MPa, and the time is 140 minutes. Among them, the amount of titanium dioxide powder, a separating agent, added is 5% of the total mass of the premixed slurry.

[0051] 4) The spinning solution is squeezed out from the spinneret, and then immersed in a coagulation bath containing an aqueous solution with a concentration of 18% NMMO to coagulate and form a primary fiber bundle, which is then drawn, washed, cut, washed, oiled and dried to obtain a high-density fibrillated Lyocell fiber with a fineness of 1.33 dtex, a dry breaking strength of 4.16 CN / dtex, a dry elongation of 14.03%, and a fibrillation index of 7.89. The obtained high-density fibrillated Lyocell fiber has good spinnability.

[0052] By comparing Examples 1, 2, and 3, it can be seen that as the amount of waste cellulose (hemicellulose) and the separating agent added increases, the amorphous region in the fiber will also increase. When cellulose absorbs a large amount of water, it swells greatly, and some hydrogen bonds are destroyed by the separating agent, making its lateral binding force weaker. In addition, due to continuous friction and bending, the cortical fibers are very easy to fall off, which significantly increases the fibrillation index of the fiber, reduces the dry strength, and increases the elongation.

[0053] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0054] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing high-density lyocell fiber from waste rubber hemicellulose, characterized in that: The steps include: S1. Soak the waste rubber backwashed from the filter in soft water to remove the solvent, so that the waste cellulose is coagulated and precipitated, and the coagulated and precipitated waste cellulose is crushed; S2, the crushed waste cellulose is added to the premix in the premixing stage, and the premixed porridge is obtained after stirring and dispersing for 40-60 minutes at a temperature of 70-100°C; the premix includes cellulose pulp, NMMO aqueous solution, hydroxylamine, etc.; S3, in the premixing stage, the separating agent material is evenly added to the premixed porridge, and then heated and decompressed to evaporate and dehydrate, so as to obtain a spinning solution with a cellulose concentration of 7 to 16 wt%; S4, the spinning solution is squeezed out from the spinneret, and then immersed in a coagulation bath containing an aqueous solution of NMMO to coagulate and form, so as to obtain a primary fiber bundle, and then the primary fiber bundle is drawn, washed, cut, washed, oiled and dried to obtain high-density lyocell fiber.

2. The method for preparing high-density lyocell fiber from waste rubber hemicellulose according to claim 1, characterized in that: The waste cellulose is added in an amount of 0.5-20% of the total amount of pulp cellulose added, and the crushed particle size is 0.1-5 mm; The total pulp cellulose addition amount is the sum of the waste cellulose and the cellulose in the premix.

3. The method for preparing high-density lyocell fiber from waste rubber 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).

4. The method for preparing high-density lyocell fiber from waste rubber hemicellulose according to claim 1, characterized in that: The cellulose pulp includes, but is not limited to, one or a combination of wood pulp, bamboo pulp, hemp pulp, straw pulp, and cotton pulp.

5. The method for preparing high-density lyocell fiber from waste rubber hemicellulose according to claim 1, characterized in that: 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.

6. The method for preparing high-density lyocell fiber from waste rubber hemicellulose according to claim 1, characterized in that: The addition amount of the separating agent material is 0.1-10% of the total cellulose mass in the premixed porridge, and the particle size of the separating agent material is ≤1 μm.

7. The method for preparing high-density lyocell fiber from waste rubber hemicellulose according to claim 1, characterized in that: In step S3, the dehydration time is 10-180 minutes, the dehydration vacuum degree is -0.095 to -0.1 MPa, and the dehydration temperature is 90-120°C.

8. The method for preparing high-density lyocell fiber from waste rubber 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°C.

9. The method for preparing high-density lyocell fiber from waste rubber hemicellulose according to claim 1, characterized in that: In step S4, the NMMO concentration in the coagulation bath is 10-25%.

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