CN110468460B

CN110468460B - Preparation method of recycled acrylic fiber and recycled acrylic fiber product

Info

Publication number: CN110468460B
Application number: CN201810450492.2A
Authority: CN
Inventors: 徐佳威; 岳福升; 李洪晨; 李振峰; 陈达志; 高岩; 段志国; 李清海; 曹冉曦; 赵显全; 申增路; 马军峰; 申欢欢; 果大东; 郭振宇; 顾可夫; 梁栋栋; 申佳
Original assignee: Hebei Aikerui Fiber Co ltd
Current assignee: Hebei Aikerui Fiber Co ltd
Priority date: 2018-05-11
Filing date: 2018-05-11
Publication date: 2022-02-18
Anticipated expiration: 2038-05-11
Also published as: CN110468460A

Abstract

The invention belongs to the field of acrylic fiber recovery, and discloses a preparation method of regenerated acrylic fibers, which comprises the following steps: (1) removing impurities from the recovered raw materials, washing with water, and drying to obtain regenerated dissolved raw materials; (2) dissolving the regenerated dissolving raw material in the step (1), filtering and purifying to obtain a regenerated acrylic fiber solution; (3) spinning the regenerated acrylic fiber solution in the step (2) to obtain nascent acrylic fiber; (4) and (4) forming and drying the nascent acrylic fiber in the step (3) to obtain the regenerated acrylic fiber. The invention also provides a regenerated acrylic fiber, wherein the breaking strength of the regenerated acrylic fiber is more than or equal to 2.0CN/dtex, the elongation at break is more than or equal to 30 percent, and the moisture regain is 1.8-2.3 percent; the performance of the regenerated acrylic fiber and the non-regenerated acrylic fiber produced by the invention is similar, the surface grooves and/or depressions of the regenerated acrylic fiber improve the moisture absorption of the fiber to a certain extent, and the recycled raw material can be a pure acrylic fiber product or a blended product of the acrylic fiber and other fibers, thereby solving the problem that the acrylic fiber cannot be recycled and being worthy of wide popularization and application.

Description

Preparation method of recycled acrylic fiber and recycled acrylic fiber product

Technical Field

The invention belongs to the field of acrylic fiber recovery, and particularly relates to a preparation method of regenerated acrylic fibers and a regenerated acrylic fiber product.

Background

With the development of global economy, the demand for energy is increasing, especially for petroleum and its derivatives, which has been nearly exhausted in the last centuries due to human transition, and some authorities and experts predict that at the present production rate, petroleum is being produced for at most fifty years. Since 0.9 ton of acrylonitrile is required for producing 1 ton of acrylon, propylene required for synthesizing acrylonitrile is derived from petroleum by-product. The acrylic fiber is mainly applied to the fields of spinning clothes, interior decoration and part of industry in daily life, along with the increasing improvement of national economy, the living standard and quality of people, higher requirements are put forward for clothes, food, live and rows, clothes as the name suggests, people basically throw away waste clothes when treating waste clothes, and because the acrylic fiber raw material belongs to aromatic high polymer polymeric materials and can hardly degrade, a large amount of waste is caused, and huge environmental pressure is increased. The processing method of the prior acrylic fiber downstream market semi-finished products and finished products is as follows:

(1) the downstream market semi-finished products of the acrylic fibers comprise acrylic wool tops, yarns and the like. The method is mainly used for reducing the price and selling the products to low-end customers, producing low-end consumable products, and directly throwing away the products after use, thereby not only wasting but also increasing the environmental pressure. The components comprise natural color or color 100 percent pure spinning acrylic fiber material, natural color or color acrylic fiber and other types of fiber blended material;

(2) the downstream market finished products of the acrylic fibers comprise daily life consumables such as clothes, carpets and indoor home textiles and part of industrial fields. One part of the disposable sanitary towel belongs to a disposable article, and the disposable sanitary towel is thrown away after being used once, most of the sanitary towel is changed after being used for a plurality of months and 2-3 years, and finally the sanitary towel is thrown away. The components of the acrylic fiber blended yarn comprise natural color or color 100 percent pure spinning acrylic fiber materials, natural color or color acrylic fibers and other types of fiber blended materials.

Application No. CN201310323618.7 discloses a method for preparing colored fibers by using waste clothes, comprising: rinsing the waste clothes with water, then cleaning, baking and drying to constant weight; cutting waste clothes into pieces, mixing the waste clothes with ionic liquid uniformly, stirring and dissolving for 1-15h at 25-130 ℃ to obtain a solution with the solute mass percentage concentration of 7-20%, and then defoaming, spinning, washing and airing to obtain the colored fiber. The method has the advantages that the process is simple, the operation is convenient, the method is green and pollution-free, is friendly to workers and environment, and improves the recycling value of old clothes, but the method has the defects that 100 percent regenerated acrylic fiber can only be spun by taking a pure acrylic fiber product as a raw material, and cannot extract and reuse acrylic fibers in an acrylic fiber blended product, and the spinning solution of the method has low concentration, cannot be purely spun, can only be added into fresh spinning stock solution in a small proportion for mixed spinning, and cannot realize large-scale production; in addition, the mechanical property of the regenerated acrylic fiber prepared by the method is far different from that of non-regenerated acrylic fiber, and the application is also limited. The process is only at the laboratory stage and the conversion to large scale production is only minimally possible.

In summary, the reason why the current acrylic fabric cannot be largely recycled and re-dissolved for recycling is as follows:

(1) the clothes have complex components and small pure spinning proportion, particularly more than 80 percent of the acrylic fabric is blended and is doped with various miscellaneous fibers such as cotton, hemp, wool, terylene and the like, and the recovery, dissolution and re-separation are difficult;

(2) at present, the concentration of the dissolved acrylic fiber is between 5 and 11 percent, the concentration of a stock solution which is normally suitable for spinning is at least more than 24 percent, and a regenerated solution after dissolution cannot be purely spun or can be mixed with a fresh stock solution only in a very small proportion (maximum 8 percent) for spinning, so that large-scale industrial production cannot be realized, and the technical bottleneck that the solution after dissolution is low in concentration and cannot be spun exists;

(3) the recycled raw material fiber is seriously damaged, and the regenerated acrylic fiber prepared by the recycled raw material has poor mechanical property and cannot be widely applied.

The present invention has been made in view of this situation.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides regenerated acrylic fibers with the fiber mechanical property reaching the non-regenerated acrylic fiber standard, has wide raw material coverage, and solves the problem that acrylic fabrics are difficult to recycle due to complex components.

In order to solve the technical problem, the invention provides a preparation method of recycled acrylon, which is characterized by comprising the following steps:

(1) removing impurities from the recovered raw materials, washing with water, and drying to obtain regenerated dissolved raw materials;

(2) dissolving the regenerated dissolving raw material in the step (1), filtering and purifying to obtain a regenerated acrylic fiber solution;

(3) spinning the regenerated acrylic fiber solution in the step (2) to obtain nascent acrylic fiber;

(4) forming and drying the nascent acrylic fiber in the step (3) to obtain regenerated acrylic fiber;

the concentration of the solution dissolved in the step (2) is 22-32%, preferably 24-28%.

The purification of the invention is to remove low molecular substances by vacuumizing and heating, and simultaneously remove fine impurities by adopting precise filtration.

In the scheme, the raw materials are 100 percent of acrylic fiber and products thereof and one or more than two blended textile products of the acrylic fiber and fibers such as terylene, cotton, wool and the like. The acrylic fiber pure spinning or blended spinning product comprises wool, woolen yarn, a blanket, sportswear, overcoat, artificial fur, plush, bulked yarn, hose, parasol cloth, curtain cloth, tarpaulin, plush toy and the like. The principle of raw material selection is that the higher the content ratio of the acrylic fiber components in the recovered raw material is, the higher the priority is, but the acrylic fiber and the product with acrylonitrile AN and vinyl acetate VA as the first monomer and the second monomer are selected most preferentially. Because the components of the prior textile are complex, the pure spinning proportion is small, especially more than 80 percent of the acrylic fabric is blended products which are doped with various miscellaneous fibers such as cotton, hemp, wool, terylene and the like, and the recovery, dissolution and separation are difficult. The invention extracts the acrylic fibers from the acrylic fiber blended product as the raw material and prepares 100 percent regenerated acrylic fibers, thereby solving the problem that the existing acrylic fiber blended product can not be recycled.

In the scheme, the impurity removal in the step (1) is to remove doffing paper tubes in recovered products, buttons made of various materials on clothes, decorative articles and other doped foreign matters before washing; the washing is to purify the fabric and remove various finishing agents in the recycled fabric, and the washing conditions are as follows: desalting water at 90-100 deg.C, and circularly heating for 90-120 min; the drying is to further remove the moisture in the recovered raw materials, so as to reach the requirement of dissolved moisture, avoid the dissolution and the product quality due to the overhigh moisture, and the drying conditions are as follows: a continuous chain plate dryer, low-pressure steam heating, wherein the low-pressure steam pressure is 0.45-0.6Mpa, the temperature is 160-170 ℃, and the drying temperature is controlled to be 75-80 ℃.

In a further scheme, the step (1) further comprises raw material sorting, wherein the raw material sorting is carried out according to the proportion of the acrylic fibers in the recovered raw materials, 100% of natural color acrylic fibers and products are separately classified, 100% of colored acrylic fibers and products are separately classified, the blending proportion of the acrylic fibers and other types of fibers is greater than 50%, and the blending proportion of the acrylic fibers and other types of fibers is less than 50%; dewatering can be carried out before drying in the step (1), wherein the dewatering is to remove alkaline moisture of the recovered raw materials in the washing process to the maximum extent, reduce the steam consumption of drying in the next procedure and avoid the influence of alkali liquor; in addition, when the recycled raw materials are 100% acrylic fibers and products, the acrylic fibers are required to be crushed after being dried in the step (1), and the crushing enables the acrylic fibers to be more fully dissolved in the subsequent dissolving process. It should be noted that, when the recycled raw material is a blended product of acrylic fibers and other fibers, in order to better filter and separate the acrylic fiber solution from other undissolved fibers, a crushing step is not needed after drying.

In addition, the concentration of the solution after dissolution is 22-32%, when the concentration of the solution is lower than 22%, the concentration of the solution is too dilute, so that the subsequent purification cost is increased, and when the concentration of the solution is higher than 32%, the solution approaches the critical concentration, polymer coils are in close contact, the solution becomes thick, and the solution is not easy to filter. Therefore, in combination, the concentration after dissolution is selected to be 22 to 32%, and preferably 24 to 28%.

Further, the filtration in the step (2) adopts a three-stage filtration method, wherein the first stage filtration adopts a basket type coarse filter for filtration, the filtration pressure is 0.1-0.2Mpa, and the filtration precision is 20-120 mm; the second stage filtration is carried out by adopting a candle filter, the filtration pressure is 0.3-0.4Mpa, and the filtration precision is 0.5-1 mm; the third stage filtering is performed by using a plate and frame filter with filtering pressure of 0.5-0.7Mpa and filtering precision of 3-5 μm. In the scheme, the solution of the recycled and regenerated acrylic fiber solution is subjected to multistage filtration to remove insoluble foreign fibers and insoluble particles. The filtration conditions are as follows: the particle size of the impurities is more than 5 μm, the solid content of the filtrate is less than 26%, and the viscosity is less than 16000 deberthing (cp).

Further, the purification process of step (2) comprises:

(1) a first temperature rise stage: the heating rate is 0.5-2 ℃/min, the heating time is 30-90min, and the target temperature is 100-120 ℃;

(2) a first constant temperature stage, wherein the constant temperature time is 90-120 min;

(3) a second temperature rise stage, wherein the temperature rise rate is 0.5-1 ℃/min, the temperature rise time is 60-180min, and the temperature rise target temperature is 150-;

(4) and a second constant temperature stage: the constant temperature time is 60-90 mim;

(5) and (3) cooling: the cooling rate is 1-2 ℃/min, and the target temperature is 70-100 ℃;

the vacuum degree in the purification process is-20 to-100 kpa;

preferably, the first and second liquid crystal materials are,

(1) a first temperature rise stage: the heating rate is 0.5-1 ℃/min, the heating time is 40-60min, and the target temperature is 100-;

(2) a first constant temperature stage, wherein the constant temperature time is 100-;

(3) a second temperature rise stage, wherein the temperature rise rate is 0.8-1 ℃/min, the temperature rise time is 90-120min, and the temperature rise target temperature is 165-170 ℃;

(4) and a second constant temperature stage: the constant temperature time is 75-85 mim;

(5) and (3) cooling: the cooling rate is 1.5-2 ℃/min, and the target temperature of cooling is 80-90 ℃;

the vacuum degree in the purification process is-50 to-90 kpa.

In the scheme, the purification treatment is carried out on the regenerated acrylic fiber solution by adopting a stepped temperature rising mode. In the first temperature rise stage, the temperature of the regenerated acrylic fiber solution is gradually raised, and the cold glue phenomenon in the high-concentration solution is destroyed in the temperature rise process, so that the solution is uniformly dispersed; when the temperature is increased to 100-120 ℃, keeping constant temperature, entering a first constant temperature stage, and gradually evaporating the water in the solution in the process, thereby reducing the distance between polymer molecules and improving the polymerization degree between the polymer molecules; keeping the constant temperature for 90-120min, then entering a second temperature rising stage, wherein in the process, along with the continuous rising of the temperature, free radicals are generated among the molecules of the high polymer, on one hand, the free radicals can generate self-polymerization, partial grafting or slight crosslinking reaction, so that the molecular weight of the high polymer is increased, the chain length is increased, and branched chains are generated, therefore, the molecules are easier to tangle, the acting force among the molecules is larger, the molecular chain is relatively difficult to stretch and deform, the breaking strength of the fiber after spinning is increased to a certain extent, the molecular weight is increased, the viscosity of the regenerated acrylic fiber solution is also increased, and the spinnability of the regenerated acrylic fiber solution is improved; on the other hand, as the water content is gradually reduced, the contact probability between the high molecular polymer and the low molecular substance in the solution is increased, and the free radical in the high polymer can abstract an atom from the low molecular substance to stop the self-polymerization reaction, thereby preventing the conditions that the self-polymerization reaction causes the overlarge molecular weight and the overhigh viscosity to reduce the spinnability. When the temperature is increased to 150-190 ℃, the fiber enters a second constant temperature stage, in the process, the low molecular substances dissolved in the solution and a small amount of solvent are gradually evaporated, the content of the solvent and the low molecular substances in the fiber after spinning is reduced, on one hand, the concentration of the recovered acrylic fiber solution is improved, the spinnability is improved, and on the other hand, the adverse effect of the solvent and the low molecular substances in the fiber after spinning on the fiber performance is also reduced. And finally, entering a temperature reduction stage, and reducing the temperature of the regenerated acrylic fiber solution to a temperature capable of spinning.

In addition, the inventor surprisingly discovers that waste clothes have oligomers such as breakage and degradation of acrylic fibers due to abrasion and the like, the oligomers form high molecular chains through self polymerization in the temperature rise process and are grafted to other polyacrylonitrile molecular chains, the molecular weight of high polymers in the acrylic fiber recovery solution is increased, the intermolecular acting force is increased, the fiber strength after the spinning of the recovered acrylic fiber solution is improved to a certain extent, in addition, a small amount of low molecular substances remained in the acrylic fiber solution are recovered, the distance between high polymer molecules is increased in the acrylic fiber spinning process, the entanglement among the molecules is relatively weakened, the molecular chain segments have enough stretching space relatively, so that the plasticizing effect is achieved, the stretching and the retraction are easy, and the breaking elongation of the regenerated acrylic fibers is also improved.

The invention adopts a step heating purification mode, avoids the situation that the viscosity of the solution is increased sharply when the temperature is directly raised to the target temperature, and simultaneously, the water is continuously evaporated and bubbles appear in the solution in the process, thereby damaging the polymerization degree among molecules and causing the phenomenon that a large number of holes appear in the fiber after spinning to influence the performance of the fiber.

Further, the purification method comprises a vacuum jet circulation heating purification method, an embedded coil heating evaporator vacuum purification method, a jacket heating continuous stirring evaporator vacuum purification method and a distillation tower heating purification method, and the jacket heating continuous stirring evaporator vacuum purification method is preferably selected according to comprehensive consideration of purification effect and cost.

Further, the solvent in the dissolving process in the step (2) comprises dimethylacetamide, dimethylformamide and dimethyl sulfoxide; dimethylacetamide is preferred.

In the scheme, the solvent is selected according to the principle of polarity similarity (namely polar polymer is dissolved in a polar solvent, nonpolar polymer is dissolved in a nonpolar solvent, polymer with large polarity is dissolved in a solvent with large polarity, and polymer with small polarity is dissolved in a solvent with small polarity) and the principle of solvation, cohesive energy density or tolerance parameter similarity; when the recycled raw material is a blended product of acrylic fibers and other fibers, the acrylic fiber solution and other undissolved fibers can be separated to obtain an acrylic fiber solution with the purity close to 100 percent only by simple filtration because other fibers cannot be dissolved in dimethylacetamide, dimethylformamide and dimethyl sulfoxide; dimethylacetamide is particularly preferred.

Preferably, the heating temperature in the dissolving process is 45-90 ℃, and the heating time is 8-16 h;

more preferably, the heating temperature is 65-85 ℃ and the heating time is 8-12 h.

Further, the step (2) also comprises a solvent recovery process, and the temperature of cooling water during solvent recovery is less than 28 ℃.

In the scheme, the solvent in the purification process can be recycled as the dissolved solvent; in addition, if the preparation method adopts a wet spinning process, the spinning solution can also be used as a coagulating bath for wet spinning. By recycling the solvent, the waste of the solvent is reduced, and the resources are saved.

Further, the water washing process in the step (1) is added with an alkaline accelerator, which comprises sodium hydroxide, potassium hydroxide, water glass, trisodium phosphate, tripotassium phosphate, sodium sulfide, ammonia water and calcium hydroxide, preferably sodium hydroxide;

the alkaline accelerant accounts for 0.05 to 0.15 percent of the mass percent of the washing solution, and preferably 0.08 to 0.1 percent;

in the scheme, the alkaline promoter is added in the washing process, and the washing solution is alkaline, so that partial cations or acid dyes and finishing auxiliaries added in the after-finishing process of the recycled raw materials can be removed more favorably, and meanwhile, the prehydrolysis effect on the acrylic fibers is realized, and the-CN group in the acrylic fibers is hydrolyzed. The washing conditions are as follows: adopting a drum-type washing circulating heating method, desalting water at 90-100 ℃, and circulating heating for 90-120 minutes.

Further, a penetrating agent and an antioxidant are added in the dissolving process in the step (2);

the penetrating agent comprises sodium hydroxide, potassium hydroxide, water glass, trisodium phosphate, tripotassium phosphate, sodium sulfide, ammonia water and calcium hydroxide, preferably sodium hydroxide, and the penetrating agent accounts for 0.3-1%, preferably 0.5-0.8% of the dissolved fabric by mass;

the antioxidant stabilizer is oxalic acid and/or citric acid, preferably citric acid, and the antioxidant agent accounts for 0.1-1%, preferably 0.3-0.6% of the mass of the dissolved fabric. (ii) a

In the above scheme, in order to improve the dissolution efficiency and reduce the dissolution cost, a penetration cosolvent, such as sodium hydroxide, potassium hydroxide, water glass, trisodium phosphate, tripotassium phosphate, sodium sulfide, ammonia water, calcium hydroxide and the like, is added, because the dissolution of the acrylic fiber is accelerated under alkaline conditions, the main component of the acrylic fiber is polyacrylonitrile, the-CN in the molecule of the acrylic fiber is easily hydrolyzed under the action of a strong alkaline medium, the-CN group is hydrolyzed to-CONH 2 firstly, and then is further hydrolyzed to-COOH and-COONa groups, and the most sodium hydroxide is generally used as an accelerator. Due to the addition of the penetrating cosolvent, on one hand, the generated hydrolytic groups improve the hydrophilicity of polyacrylonitrile, and simultaneously, the surface of the polyacrylonitrile is favorably roughened in the spinning process. In addition, because the heating time is long when the acrylic fibers are dissolved, the polymer in the acrylic fiber stock solution is unstable, and in order to ensure the stability of the solution, a certain amount of antioxidant stabilizer needs to be added, so that the hydrolysis of the polymer in the recycled fabric due to long-time heating and pH value rise in the dissolving process, namely the generation of yellow miazines is prevented, the whiteness of the regenerated solution is improved, and meanwhile, the NaOH solution in the solution is neutralized and removed. Since citric acid is relatively weak in acidity, less corrosive and good in thermal stability, it is preferable that the amount of citric acid added is 0.1 to 1%, preferably 0.3 to 0.6% of the amount of the raw material in a batch.

In a further scheme, when the colorless acrylic fiber recycled raw material is dissolved, a color correcting agent needs to be added, so that the recycled acrylic fiber after spinning is closer to the natural color. The color correcting agent is a carbazole color correcting agent, preferably carbazole violet blue, and the mass percentage of the carbazole violet blue in the dissolved fabric is 0.04-0.13%, preferably 0.047-0.07%.

Further, the spinning in the step (3) is the direct spinning of the regenerated acrylic fiber solution in the step (2);

or the regenerated acrylic fiber solution in the step (2) is mixed with the fresh spinning stock solution and then spun;

the raw materials of the fresh spinning solution comprise acrylonitrile accounting for 90.1-94.25% of the total amount of the spinning solution and vinyl acetate accounting for 5.75-9.15% of the total amount of the spinning solution.

In the scheme, because the direct spinning can be carried out when the concentration of the spinning solution is more than 25 percent, the concentration of the dissolved solution is 22-35 percent, preferably 24-28 percent, and the direct spinning can be carried out within the concentration range after purification without adding into fresh spinning solution.

Further, when the regenerated acrylic fiber solution and the fresh spinning solution are mixed for spinning, the mass ratio of the regenerated acrylic fiber solution to the fresh spinning solution is more than 0.5:1, preferably more than 1: 1.

In the above scheme, if the regenerated spinning solution needs to be added into the fresh spinning solution for spinning, the regenerated spinning solution can be added into the fresh spinning solution in a large proportion due to the high concentration of the regenerated spinning solution, and the addition ratio of the regenerated spinning solution to the fresh spinning solution is greater than 0.5:1, preferably greater than 1: 1.

In a further scheme, the regenerated acrylic fiber spinning solution needs to be subjected to precise filtration to remove more tiny impurities in the spinning solution, and the influence of blockage of a spinneret plate by the impurities on spinning spinnability and fiber quality in the spinning process is reduced. The precise filtering conditions are as follows: the temperature is 85-90 ℃, the filtration precision is less than or equal to 5 microns, and the pressure difference is 0-1 Mpa. The regenerated acrylic fiber solution is precisely filtered and then injected into the fresh spinning solution in a pre-spinning injection mode.

Further, the spinning in the step (3) is dry spinning or wet spinning, preferably wet spinning.

In the scheme, the concentration range of wet spinning is 23-25%, the concentration of dry spinning is more than 25%, and the concentration range of the purified product is 22-35%, preferably 24-28%, so that dry spinning or wet spinning can be adopted.

The wet spinning is carried out by DMAC wet two-step spinning in a spinning coagulating bath, wherein the mass percent of the solvent in the spinning coagulating liquid is 40-60%, and the temperature of the coagulating bath is 30-50 ℃. Compared with NaSCN wet spinning and dry DMF acrylic fiber spinning processes, the process has the advantages of short spinning process route, small occupied area, flexible operation, high production efficiency, low energy consumption, low production cost and the like, so the wet process is preferred. It should be noted that the solvent used in the wet spinning coagulation bath may be the solvent recovered in step (2).

In a further scheme, when the spinning mode is wet spinning, the regenerated acrylic fiber dissolved solution prepared by filtering is fully mixed by 2 homogenizing static mixers to carry out wet two-step spinning, and the wet two-step spinning process comprises the following steps: the concentration of solvent in the coagulating bath liquid is 40-60%, the coagulating bath temperature is 30-50 deg.C, the nascent fiber sprayed from the coagulating bath is subjected to double diffusion forming, water washing, oiling, drying and curling, and the drafting multiple is 4-10 times.

The invention also provides a regenerated acrylic fiber prepared by the preparation method, and the breaking strength of the regenerated acrylic fiber is more than or equal to 2.0

CN/dtex, elongation at break is more than or equal to 30%, and moisture regain is 1.8-2.3%;

preferably, the cross section of the regenerated acrylic fiber has a kidney-shaped section, burrs are arranged on the edge of the section, dents are arranged on at least one side of the waist, the surface of the fiber is rough, and a small number of grooves and/or depressions are formed;

in the scheme, the regenerated acrylic fibers manufactured by the method disclosed by the invention are soft in handfeel and soft in color, have specific colors, are determined by the colors of the acrylic fibers recycled in batches and products thereof, do not need to be dyed, avoid the pollution of subsequent dyeing procedures to the environment, and are energy-saving and environment-friendly. The breaking strength is more than or equal to 2.0CN/dtex, the breaking elongation is more than or equal to 30 percent, the index is close to that of the conventional acrylic fiber, and the fiber has the characteristics different from that of the conventional fiber. The regenerated acrylic fiber can be spun purely and can be blended with other fibers according to any proportion, and the fiber fabric prepared by the method can be widely applied to the fields of spinning, carpets and various indoor decorations.

In the scheme, as the raw materials for manufacturing the regenerated acrylic fibers are acrylic fibers and products or blended products of the acrylic fibers and other fibers, the spinning solution after dissolution and purification still contains a very small amount of small molecular substances and trace impurities, and a small amount of grooves and/or depressions are formed on the surface of the acrylic fibers after filamentation.

After the technical scheme is adopted, compared with the prior art, the invention has the following beneficial effects.

1. The invention utilizes the principle of polar similarity and intermiscibility, selects dimethyl acetamide, dimethyl formamide or dimethyl sulfoxide and the like as the dissolving solvents of the recycled raw materials, and solves the problem that the blended acrylic fabric is difficult to recycle due to complex components because the solvents only dissolve acrylic fibers and do not dissolve other fibers;

2. the performance indexes of the regenerated acrylic fibers produced by the method are close to those of conventional fibers, the breaking strength is more than or equal to 2.0CN/dtex, the elongation at break is more than or equal to 30 percent, and the regenerated acrylic fibers are different from the regenerated acrylic fibers of the conventional fibers;

3. the invention solves the technical bottleneck that the acrylic fiber after being dissolved has low concentration and can not be added into the fresh spinning solution in a large proportion for spinning and even pure spinning; by the preparation method, the concentration of the acrylic fiber regenerated solution after dissolution is 22-35%, preferably 24-28%, the acrylic fiber regenerated solution can be added into a fresh spinning solution in a large proportion and even directly pure-spun, and a new thought for realizing large-scale industrial production is explored;

4. the invention adopts a step-type heating purification mode, which not only improves the spinnability of the spinning solution, but also avoids the fiber performance from being influenced by the formation of a large number of holes on the fiber surface during the evaporation of water;

5. the fiber prepared by the process method has the color characteristic similar to that of the stock solution dyed fiber, has specific color, is various in color, does not need to be dyed again, and is energy-saving and environment-friendly;

6. the whole process is energy-saving and environment-friendly, and waste liquid generated in the process treatment can be recycled, so that resource waste and environmental pollution are reduced.

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a cross-sectional electron microscope image of the regenerated acrylic fiber produced by the present invention.

FIG. 2 is an electron microscope image of the cross section of the recycled acrylic fiber clothing fiber.

FIG. 3 is a cross-sectional electron microscope image of non-regenerated acrylic fiber.

FIG. 4 is an electron microscope image of the surface of the regenerated acrylic fiber produced by the present invention.

FIG. 5 is an electron microscope image of the surface of the recycled acrylic fiber clothing fiber.

FIG. 6 is an electron microscope image of the surface of non-recycled acrylic fiber.

It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but to illustrate it by a person skilled in the art with reference to specific embodiments.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.

Example 1

Regenerated acrylic fiber with 100% of natural color acrylic fiber as raw material

The preparation method comprises the following steps:

(1) removing foreign matters such as a yarn bobbin from the recovered raw material, washing with water, adding an alkaline sodium hydroxide promoter accounting for 0.05 percent of the mass of a washing solution in the washing process, and finally drying the washed raw material to obtain a regenerated dissolved raw material; in order to facilitate better subsequent dissolution, the regenerated dissolution raw material needs to be crushed before dissolution.

(2) Putting the regeneration dissolving raw material in the step (1) into a dimethylacetamide solution for dissolving, wherein the heating temperature in the dissolving process is 100 ℃, and the heating time is 30 min; and adding a sodium hydroxide penetrating agent accounting for 0.3 percent of the mass of the dissolved fabric, a citric acid antioxidant accounting for 0.3 percent of the mass of the dissolved fabric and a carbazole violet-blue color correcting agent accounting for 0.04 percent of the mass of the dissolved fabric in the dissolving process, and filtering the solution after the dissolution is finished, wherein the concentration of the regenerated acrylic fiber solution is 26 percent.

(3) Purifying the filtrate in the step (2), wherein the purification stage comprises: a first temperature rise stage: the heating rate is 0.5 ℃/min, the heating time is 90min, and the target temperature is 100 ℃; a first constant temperature stage, wherein the constant temperature time is 90 min; a second temperature rise stage, wherein the temperature rise rate is 0.5 ℃/min, and the temperature rise target temperature is 165 ℃; and a second constant temperature stage: the constant temperature time is 90 mim; and (3) cooling: the cooling rate is 1 ℃/min, and the target temperature of cooling is 70 ℃; the vacuum degree in the purification process is-20 kpa; the regenerated acrylic fiber solution may be subjected to a microfiltration process in order to remove finer impurities.

(4) Directly spinning the regenerated acrylic fiber solution in the step (2) by adopting a dimethyl acetamide wet method two-step method to obtain nascent acrylic fiber;

(5) forming and drying the nascent acrylic fiber in the step (3) to obtain regenerated acrylic fiber; the breaking strength of the obtained regenerated acrylic fiber is 2.6 CN/dtex, and the breaking elongation is 31 percent.

Examples 2-6 were carried out in a similar manner to example 1, and the specific process and performance criteria are given in Table I.

Table one:

comparative example 1

The comparative example is the same as the example 1, except that the method of CN201310323618.7 is adopted, the concentration after dissolution is 13%, the breaking strength of the regenerated acrylic fiber is 1.6Kpa, the breaking elongation is 26%, and the moisture regain of the fiber is 1.5%.

Comparative example 2

The comparative example is the same as the example 1 in raw material process, except that the purification process is not adopted, the concentration of the regenerated acrylic fiber after the dissolution by the method is 26 percent, the breaking strength of the prepared regenerated acrylic fiber is 1.9Kpa, the breaking elongation is 23 percent, and the moisture regain of the fiber is 1.4 percent.

Comparative example 3

The comparative example is the same as the raw material process of the example 1, except that the purification stage does not adopt a step-type heating mode, but directly heats to 165 ℃ and then keeps constant temperature, the concentration after dissolution is 26 percent and the concentration after purification is 29 percent by adopting the method, the breaking strength of the prepared regenerated acrylic fiber is 1.4Kpa, the breaking elongation is 18 percent and the fiber moisture regain is 1.7 percent.

Experimental example 1

The experimental example is used to compare the performance parameters of the regenerated acrylic fiber and the non-regenerated acrylic fiber prepared in example 1 and comparative examples 1-3, and is shown in Table II.

Table two:

from the above experimental results, it can be seen that the regenerated acrylic fiber prepared in example 1 has similar breaking strength and breaking elongation to the non-regenerated acrylic fiber, and has better hygroscopicity than the non-regenerated acrylic fiber; the breaking strength and the breaking elongation of the regenerated acrylic fiber prepared in the comparative examples 1-3 are obviously lower than those of the non-regenerated acrylic fiber, and the moisture regain of the fiber is slightly higher than that of the non-regenerated acrylic fiber. The reason for this is that the purification process is adopted in the preparation method of example 1, the small molecular impurities and part of the water content are reduced in the purification process, the distance between the polymer molecules is shortened, the degree of polymerization is increased, the intermolecular force is enhanced, and the breaking strength and the breaking elongation are both improved after spinning and forming, even the performance of the non-regenerated acrylic fiber is close to that of the non-regenerated acrylic fiber. In addition, because a small amount of micromolecules and moisture exist in the fibers, a small amount of grooves and depressions exist on the surfaces of the fibers, and the moisture absorption performance of the fibers can be greatly improved without greatly influencing the performance of the fibers. And comparative example 1 adopts patent No.

The preparation method of CN201310323618.7 has low concentration after being dissolved, the spinning can be carried out only by adding the dissolved solution into a fresh spinning solution, and a large amount of low molecular substances such as finishing agents and the like in the fiber post-processing process, such as oil agents, organic and inorganic salts and the like, exist in the spinning solution, the performance of the fiber after spinning is seriously influenced, and because of the existence of low molecular impurities, a large amount of grooves and depressions exist on the surface of the fiber, the breaking strength and the breaking elongation of the fiber are seriously influenced; comparative example 2 has no purification process, and the spinning solution also contains a large amount of low molecular impurities, moisture and solvents, which seriously affect the fiber performance; in the comparative example 3, the purification temperature is directly increased to the target temperature in the purification process, the viscosity of the solution is rapidly increased after dissolution and evaporation, and simultaneously the water evaporation is also carried out, so that the bubbling phenomenon appears on the surface of the solution, the polymerization degree among high polymer molecules is damaged, and a large number of grooves and depressions appear on the fiber after filamentation, thereby affecting the performance of the fiber; in addition, the large number of grooves and cracks on the surface of the fibers in comparative examples 1 to 3 also resulted in a slight increase in the moisture regain.

Experimental example 2

By comparing the section electron microscope picture (as shown in figure 1) of the regenerated acrylic fiber prepared by the invention, the fiber section electron microscope picture (as shown in figure 2) of the recycled acrylic fiber clothes and the section electron microscope picture (as shown in figure 3) of the non-regenerated acrylic fiber, it can be obviously seen that the cross section of the regenerated acrylic fiber presents a typical waist shape almost the same as the non-regenerated acrylic fiber, only the surface of the regenerated acrylic fiber is slightly burred compared with the original acrylic fiber, and the small amount of burs are beneficial to moisture absorption and perspiration and improve dyeing property, meanwhile, the physical index of the regenerated acrylic fiber is close to that of the non-regenerated acrylic fiber and the moisture regain is slightly higher than that of the non-regenerated fiber through the experimental data of the experimental example 1; the recycled acrylic fabric is worn and washed for a long time, and then seriously abrades the fiber, the edge of the section of the fiber is rough, the cross section has a large number of cracks, and the physical index is greatly reduced. In conclusion, the regenerated acrylic fiber can replace the primary acrylic fiber, and is slightly superior to the primary acrylic fiber in the aspects of moisture absorption and sweat releasing;

by comparing the surface electron microscope image (as shown in figure 4) of the regenerated acrylic fiber prepared by the invention, the surface electron microscope image (as shown in figure 5) of the fiber of the recycled acrylic fiber clothes and the surface electron microscope image (as shown in figure 6) of the non-regenerated acrylic fiber, it can be seen that the surface of the regenerated acrylic fiber is smoother and has little difference with the surface of the original fiber, and the surface of the recycled acrylic fiber has a few grooves and depressions which can also improve the moisture absorption and dyeing property of the fiber, while the recycled acrylic fiber clothes are seriously worn and washed after being worn for a long time, and the surface of the fiber has a great amount of obvious cracks, which shows that the surface of the fiber can be repaired to a certain extent after a series of treatments of the regenerated acrylic fiber prepared by the invention.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The preparation method of the recycled acrylon is characterized by comprising the following steps:

the concentration of the solution dissolved in the step (2) is 22-32%;

the purification process of the step (2) comprises the following steps:

the vacuum degree in the purification process is-20 to-100 kpa.

2. The method for preparing recycled acrylon in claim 1, characterized in that the concentration of the solution after dissolving in step (2) is 24-28%.

3. The method for preparing recycled acrylon according to claim 1, characterized in that the purification process of step (2) comprises:

the vacuum degree in the purification process is-50 to-90 kpa.

4. The method for preparing acrylic fibers for recycling as claimed in claim 1, wherein the solvent used in the dissolving process of step (2) comprises dimethylacetamide, dimethylformamide and dimethylsulfoxide.

5. The method for preparing acrylic fibers for recycling as claimed in claim 4, wherein the solvent used in the dissolving process of step (2) is selected from dimethylacetamide.

6. The method for preparing acrylic fibers for recycling as claimed in claim 1, wherein the step (2) further comprises a solvent recovery process, and the temperature of the cooling water during the solvent recovery process is less than 30 ℃.

7. The method for preparing recycled acrylon according to claim 1, characterized in that the water washing process in step (1) is added with alkaline accelerator, which comprises sodium hydroxide, potassium hydroxide, water glass, trisodium phosphate, tripotassium phosphate, sodium sulfide, ammonia water and calcium hydroxide; the alkaline accelerant accounts for 0.05-0.15% of the mass of the washing solution.

8. The method for producing recycled acrylic fiber as claimed in claim 7, wherein the alkali promoter is selected from the group consisting of sodium hydroxide; the alkaline accelerant accounts for 0.08-0.1% of the mass of the washing solution.

9. The method for preparing acrylic fibers for recycling as claimed in claim 1, wherein a penetrant and an antioxidant are further added during the dissolving process in the step (2);

the penetrating agent comprises sodium hydroxide, potassium hydroxide, water glass, trisodium phosphate, tripotassium phosphate, sodium sulfide, ammonia water and calcium hydroxide, and the penetrating agent accounts for 0.3-1% of the dissolved fabric by mass percent;

the antioxidant comprises oxalic acid and/or citric acid, and accounts for 0.1-1% of the dissolved fabric.

10. The method for preparing acrylic fibers for regeneration as claimed in claim 9, wherein the penetrating agent is selected from sodium hydroxide, and the penetrating agent accounts for 0.5-0.8% of the dissolved fabric by mass;

the antioxidant is selected from citric acid, and accounts for 0.3-0.6% of dissolved fabric.

11. The method for preparing recycled acrylic fibers as claimed in claim 1, wherein the spinning in the step (3) is a direct spinning of the recycled acrylic fiber solution in the step (2);

12. The method for producing recycled acrylic fibers as claimed in claim 11, wherein the mass ratio of the recycled acrylic fiber solution to the fresh spinning dope is more than 0.5:1 when the recycled acrylic fiber solution is mixed with the fresh spinning dope for spinning.

13. The method for producing recycled acrylic fibers as claimed in claim 12, wherein the mass ratio of the recycled acrylic fiber solution to the fresh spinning dope is more than 1:1 when the recycled acrylic fiber solution is mixed with the fresh spinning dope for spinning.

14. The method for preparing recycled acrylon according to claim 1, characterized in that the spinning in step (3) is dry spinning or wet spinning.

15. The method for producing recycled acrylic fibers as claimed in claim 14, wherein the spinning in the step (3) is a wet spinning.

16. The regenerated acrylic fibers are characterized by being prepared by the preparation method of any one of claims 1 to 15, and having the breaking strength of more than or equal to 2.0CN/dtex, the elongation at break of more than or equal to 30 percent and the moisture regain of 1.8 to 2.3 percent.