CN114197082A

CN114197082A - Composite functional filament with core-shell structure and preparation method thereof

Info

Publication number: CN114197082A
Application number: CN202111536384.5A
Authority: CN
Inventors: 吴美燕; 李滨; 刘超; 于光; 刘哲轩; 崔球
Original assignee: Qingdao Institute of Bioenergy and Bioprocess Technology of CAS
Current assignee: Qingdao Institute of Bioenergy and Bioprocess Technology of CAS
Priority date: 2021-12-15
Filing date: 2021-12-15
Publication date: 2022-03-18
Anticipated expiration: 2041-12-15
Also published as: CN114197082B

Abstract

The invention provides a method for preparing functional composite fiber filaments with core-shell structures. The method comprises the following steps: (1) aqueous solutions/dispersions of anionic polymers and of cationic polymers were prepared at concentrations of 0.1 to 1.2% by weight. The charge density of the anionic polymer and the charge density of the cationic polymer are both 0.5 to 3.0 mmol/g. (2) Adding an auxiliary agent into the anionic polymer aqueous solution/dispersion liquid or the cationic polymer aqueous solution/dispersion liquid, and uniformly stirring to obtain the anionic polymer aqueous solution/dispersion liquid I and the cationic polymer aqueous solution/dispersion liquid I. (3) Adding the anionic polymer solution/dispersion solution I to the bottom of the spinning pipe, adding the cationic polymer solution/dispersion solution I, stretching an interfacial viscous barrier to obtain wet fiber filaments, and drying to obtain the functional composite fiber filaments. The invention not only improves the strength of the composite fiber filament and obtains unexpected good wet strength, but also can be applied in a spinning device, improves the spinning efficiency and has important practical application prospect.

Description

Composite functional filament with core-shell structure and preparation method thereof

Technical Field

The invention belongs to the field of materials, relates to a functional fiber filament with a core-shell structure and a preparation method thereof, and particularly relates to a high-strength and water-resistant functional composite filament.

Background

At present, the spinning methods of fiber filaments mainly include wet spinning, dry spinning, electrostatic spinning and the like. Of these, wet spinning is the most common method and requires shaping in a coagulation bath (usually an organic solvent). The coagulation bath is not needed in the dry spinning process, but the uniformity and strength of the obtained fiber filament are to be improved. Electrospinning is simple to operate, but requires a special spinning device, and it is difficult to obtain separate individual fibers, and the resulting fiber mat has low strength (J biomed. The electrostatic self-assembly spinning is a method for preparing composite fibers by complexing a cationic polymer and an anionic polymer through electrostatic interaction. Compared with the prior general method, the method not only has the advantages of simple process, spinning in an aqueous phase system and no need of coagulating bath forming (ACS Sustain. chem. Eng.,2020,8(2), 1137) and 1145), but also the fiber filament obtained by spinning has better reprocessing performance. Therefore, the composite fiber filament prepared by the electrostatic self-assembly method has great application potential.

However, in practical application, a plurality of problems occur, and the application of the spinning by the electrostatic self-assembly method is limited. (1) The electrostatic self-assembly spinning speed is low, and the strength of the obtained fiber filament is low. (2) The electrostatic self-assembly method generally utilizes raw materials which can be dissolved or dispersed in water, so that the prepared composite fiber filament does not have water resistance, namely the wet strength of the filament is low, and the practical application cannot be met. (3) The electrostatic self-assembly spinning reported at present (ACS Sustain. chem. Eng.,2020,8(2),1137-1145) can not meet the condition of industrial continuous production.

Disclosure of Invention

Aiming at the problems of the fiber filament preparation method in the prior art, the invention provides a method for preparing a functional composite fiber filament with a core-shell structure. The method of the invention not only improves the strength of the composite fiber filament, obtains unexpected good wet strength, but also meets the condition of automatic continuous spinning, can be applied in a tubular spinner, thereby greatly improving the spinning efficiency and having important practical application prospect.

The technical scheme of the invention is as follows: the preparation method of the composite functional filament with the core-shell structure comprises the following steps:

(1) preparation of aqueous polymer solution/dispersion: weighing 100 parts by weight of each of the anionic polymer and the cationic polymer, respectively adding a proper amount of water, and uniformly stirring to obtain 0.1-1.2wt% of anionic polymer aqueous solution/dispersion and cationic polymer aqueous solution/dispersion. Wherein the charge density of the anionic polymer and the charge density of the cationic polymer are both 0.5 to 3.0 mmol/g. The anionic polymer is a bio-based natural anionic polymer, and the cationic polymer is a bio-based natural cationic polymer.

(2) Preparation of aqueous polymer solution/dispersion for drawing I: adding a proper auxiliary agent into the anionic polymer aqueous solution/dispersion liquid or the cationic polymer aqueous solution/dispersion liquid prepared in the step (1), and stirring until the mixture is uniformly mixed to obtain an anionic polymer aqueous solution/dispersion liquid I and a cationic polymer aqueous solution/dispersion liquid I. The auxiliary agent comprises 0.1-5 parts by weight of dry strength agent, 0.1-5 parts by weight of wet strength agent and 1-20 parts by weight of functional material. The dry strength agent and the wet strength agent are introduced, so that the rheological property of the spinning solution is improved, the spinning speed is increased, more hydrogen bonds and covalent bond connection are promoted to be formed between two polymers, the strength of the composite fiber filament is greatly improved, and especially, the unexpected good wet strength is obtained.

The dry strength agent is one or more of polyacrylamide, glyoxal polyacrylamide, polyvinyl alcohol and the like; the wet strength agent is one or more of epichlorohydrin, polyamide polyamine epichlorohydrin, urea resin, melamine formaldehyde resin and polyethyleneimine. The functional material is one or more of borax, nano montmorillonite, calcium carbonate powder, ferroferric oxide nano particles, polyaniline and nano silver particles.

The aqueous solution/dispersion of the assistant is uncharged or has the same charge as the aqueous solution/dispersion of the polymer to be added; the principle of adding the dry strength agent, the wet strength agent and the functional material is as follows: (a) when the aqueous solution/dispersion of the auxiliary agent is uncharged, the auxiliary agent can be selectively added into the anionic polymer aqueous solution/dispersion or the cationic polymer aqueous solution/dispersion; (b) when the aqueous solution/dispersion of the auxiliary agent is positively charged, the auxiliary agent can only be added into the cationic polymer aqueous solution/dispersion I; (c) when the aqueous solution/dispersion of the auxiliaries is negatively charged, it can only be added to the aqueous solution/dispersion I of the anionic polymer. Therefore, the phenomenon that the fiber filament cannot be prepared in the later period due to the fact that the floccule is generated by electrostatic self-assembly in the earlier period is effectively avoided.

(3) Preparing functional composite fiber filaments: firstly, adding the anionic polymer solution/dispersion solution I prepared in the step (2) into the bottom of a spinning pipe, then slowly adding the cationic polymer solution/dispersion solution I prepared in the step (2), stretching a viscous barrier at the interface of the anionic polymer solution/dispersion solution I and the cationic polymer solution/dispersion solution I to obtain wet fiber filaments, and drying to obtain the high-strength water-resistant functional composite fiber filaments. The diameter of the spinning pipe is 5-50mm, and the spinning and drawing speed is 50-100 cm/min. The drying specifically comprises the following steps: drying at 50-105 deg.C for 5-60 min. The diameter of the prepared composite fiber filament can be adjusted by controlling the diameter of the spinning pipe and/or the speed of spinning and drawing.

In this step, the order of addition of the polymers must be: the anionic polymer is added first and the cationic polymer is added. The inventors have found that it is not possible to obtain fibre filaments in the reverse order, which would not be expected by the person skilled in the art from the prior art. This is because the mechanism of forming the fiber filament is: the cationic polymer and the anionic polymer first form a cross-linked barrier at an interface by electrostatic interaction, and then the spinning process forms a plurality of core fibers by breaking the cross-linked barrier; as the fibers are drawn, the core fibers gradually gather into individual wet fibers (fiber filaments). The core fiber is formed by wrapping anionic polymer with cationic polymer. However, if a cationic polymer is added first, it cannot form an effective coating on an anionic polymer, and thus a filament having an outer layer of the cationic polymer and an inner layer of the anionic polymer cannot be obtained.

Preferably, the anionic polymer is one or more of anionic guar gum, anionic starch, sodium alginate, anionic cellulose and anionic lignin, and the cationic polymer is one or more of cationic guar gum, cationic starch, chitosan and cationic cellulose.

Preferably, the specific adding method of the auxiliary agent in the step (2) is as follows: the addition of the auxiliaries to the same polymer solution should be done sequentially and the latter added under conditions of sufficient stirring to avoid agglomeration.

The functional composite fiber filament prepared by the method has a core-shell structure, wherein the core-shell structure comprises a core layer and a shell layer coated on the outer side of the core layer; the shell layer is made of cationic polymer, and the core layer is made of anionic polymer. Due to the special core-shell structure of the filament, the added functional materials are reserved in the preparation process of the fiber filament, so that the fiber filament has corresponding flame retardance, magnetism, conductivity and antibacterial property.

The diameter of the functional composite fiber filament is 10-100 μm, and the orientation degree of the composite fiber is 0.6-0.8. The dry strength of the functional composite fiber filament is 150-2000MPa, and the wet strength is 30-300 MPa. Compared with the fiber filament prepared by the electrostatic self-assembly method without adding the reinforcing agent, the dry strength is increased by 2-5 times, and the wet strength is increased by 2-10 times.

The invention has the beneficial effects that:

(1) the invention provides a method for preparing high-strength and water-resistant functional composite fiber filaments, which is simple to operate and low in cost, can be applied to a tubular spinner and has automatic continuous spinning conditions, so that the spinning efficiency is greatly improved, and the method has an important industrial application prospect.

(2) According to the method, a brand-new spinning solution formula is provided, so that the wet strength of the prepared composite fiber filament is improved, and an unexpected technical effect is achieved; the defect that the wet strength of the filament prepared by the electrostatic self-assembly method in the prior art is low is overcome, so that the filament has practical application value and great economic benefit prospect.

(3) The composite fiber filament with the core-shell structure prepared by the method can be prepared into a functional fiber filament with magnetism, antibacterial property, fire resistance or electric conduction by introducing a functional material into a system, and has wide application prospect in high added value fields of response devices, electromagnetic shielding, medical supplies and the like.

Drawings

FIG. 1 shows the test results of the flame-retardant composite fiber filament prepared in example 1 using a universal tensile machine according to the present invention.

Fig. 2 is a physical diagram of the high-strength, water-resistant magnetic composite fiber filament prepared in example 2 of the present invention.

FIG. 3 is a scanning electron micrograph of a magnetic composite fiber filament prepared in example 2 of the present invention.

Fig. 4 is a distribution diagram of iron element of the magnetic composite fiber filament prepared in comparative example 2 of the present invention.

Fig. 5 is a magnetization curve of the magnetic composite fiber filament prepared in example 2 of the present invention.

FIG. 6 is a drawing operation chart of a wet conjugate fiber filament prepared in example 3 of the present invention.

Fig. 7 is a diagram of an embodiment of the high-strength, water-resistant antimicrobial composite filament prepared in example 3 of the present invention.

Fig. 8 is a two-dimensional wide-angle X-ray diffraction pattern (a) and a diffraction spectrum (B) of the antibacterial composite fiber filament prepared in example 3 of the present invention.

Fig. 9 is a scanning electron microscope image of a high-strength, water-resistant conductive composite fiber filament prepared in example 4 of the present invention.

Fig. 10 is a pictorial view of a high strength, water resistant magnetic composite filament made in example 7 of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples.

The feasibility of the process is further described below by means of specific implementation examples, without the intention that the invention is limited to these examples.

Example 1:

100g of cationic nanocellulose was added to an appropriate amount of water to prepare a dispersion solution at a concentration of 0.1 wt%, and 100g of TEMPO-oxidized nanocellulose (anionic nanocellulose) was added to an appropriate amount of water to prepare a dispersion solution at a concentration of 0.5 wt%. Wherein the charge density of the cation nano-cellulose is 0.5mmol/g, and the charge density of the anion nano-cellulose is 1.5 mmol/g. 250g (dry weight 5g) of polyvinyl alcohol solution with the concentration of 2wt% and 0.1g of melamine formaldehyde resin are sequentially added into the cationic nanocellulose dispersion liquid, and are respectively stirred to be uniformly mixed, so that the cationic nanocellulose dispersion liquid I is obtained. Adding 5g of borax into the anionic nano-cellulose dispersion liquid, and stirring to uniformly mix to obtain the anionic nano-cellulose dispersion liquid I. Dropping the anionic nano-cellulose dispersion solution I at the bottom of a spinning pipe with the diameter of 10mm, then dropping the cationic nano-cellulose dispersion solution I, and upwards stretching the two interface layers at the stretching speed of 70cm/min to obtain the wet fiber. And (3) drying the wet fibers in a drying oven at 105 ℃ for 5min to obtain the high-strength and water-resistant flame-retardant composite fiber filament. However, in the spinning process, the cationic nanocellulose dispersion I is dropped into the spinning tube first, and then the anionic nanocellulose dispersion I is dropped, and the interface layer is pulled upward, so that wet fibers cannot be obtained. It was measured that the filament diameter of the flame-retardant composite fiber prepared in example 1 was 10 μm. Meanwhile, when the flame-retardant composite fiber filament is tested by using a universal tensile machine, as can be seen from fig. 1, the dry strength of the composite fiber filament is 1879MPa, and the wet strength is 218 MPa. Through two-dimensional wide-angle X-ray diffraction pattern analysis, the flame-retardant composite fiber filament has an obvious core-shell structure, the full width at half maximum (FWHM) of a strongest ring intensity distribution curve on the equator is taken, and the orientation degree (pi) of the composite filament is calculated to be 0.8 according to Eq.1.

Comparative example 1:

cationic and anionic nanocellulose dispersions were prepared and spun as described in example 1 without addition of dry strength agent (polyvinyl alcohol) and wet strength agent (melamine formaldehyde resin). Experiments have found that neither cationic nor anionic nanocellulose dispersions can yield fibres by electrostatic self-assembly, regardless of the order of addition of the two. This is because the addition of the dry strength agent in example 1 effectively adjusted the rheological properties of the cationic nanocellulose dispersion, and further, long fibers could be obtained by electrostatic self-assembly.

Example 2:

adding 100g of cationic guar gum into a proper amount of water to prepare a solution with the concentration of 1.2 wt%; 100g of TEMPO oxidized nanocellulose (anionic nanocellulose) was added to an appropriate amount of water to prepare a dispersion having a concentration of 0.1 wt%. Wherein the charge density of the cationic guar gum is 0.5mmol/g, and the charge density of the anionic nanocellulose is 3.0 mmol/g. And (3) sequentially adding 20g (dry weight 0.1g) of cationic polyacrylamide solution with the concentration of 0.5 wt% and 40g (dry weight 5g) of polyamide polyamine epichlorohydrin solution with the concentration of 12.5 wt% into the cationic guar gum solution, and respectively stirring to uniformly mix to obtain the cationic guar gum solution I. And adding 20g of nano ferroferric oxide into the anionic nano-cellulose dispersion liquid, and stirring to uniformly mix to obtain the anionic nano-cellulose dispersion liquid I. And dropping the anionic nano-cellulose dispersion solution I at the bottom of a spinning pipe with the diameter of 5mm, then dropping the cationic guar gum solution I, and upwards stretching the two interface layers at the stretching speed of 100cm/min to obtain the wet fiber. And (3) drying the wet fiber in a 50 ℃ oven for 60min to obtain the high-strength water-resistant magnetic composite fiber, wherein the substance is shown in figure 2.

Comparative example 2:

the cationic guar gum/anionic nanocellulose composite fiber filament is prepared by the method under the condition that a dry strength agent (cationic polyacrylamide) and a wet strength agent (polyamide polyamine epichlorohydrin) are not added.

It was measured that the diameter of the magnetic composite fiber filament prepared in example 2 was 60 μm, and the diameter of the composite fiber filament prepared in comparative example 2 was 29 μm. Meanwhile, the dry strength and the wet strength of the magnetic composite fiber filament prepared in example 2 were 150MPa and 30MPa, respectively, as measured by a universal tensile machine, while the dry strength and the wet strength of the composite fiber filament prepared in comparative example 2 were 75MPa and 3MPa, respectively. This shows that the dry strength of the magnetic composite fiber filaments prepared by the method of the present application is increased by 2 times and the wet strength is increased by 10 times compared to the composite fiber filaments prepared by the prior art.

In addition, as can be seen from the analysis of the two-dimensional wide-angle X-ray diffraction pattern, the magnetic composite fiber filament prepared in example 2 has an obvious core-shell structure, and the orientation degree of the composite filament is calculated to be 0.6 according to eq.1 by taking the full width at half maximum of the intensity distribution curve of the strongest ring on the equator. Meanwhile, the magnetic composite fiber filament is characterized by adopting a scanning electron microscope (fig. 3). The result shows that the magnetic ferroferric oxide particles are uniformly dispersed in the composite fiber filament. The magnetic composite fiber filament prepared in example 2 is coated with magnetic particles through the core-shell structure, so that the falling-off of the magnetic particles is effectively avoided.

Example 3:

adding 100g of chitosan into a proper amount of water to prepare a solution with the concentration of 1.0 wt%; 100g of sodium alginate is added into a proper amount of water to prepare a 1.2% concentrated solution. Wherein the charge density of the chitosan is 3.0mmol/g, and the charge density of the sodium alginate is 1.0 mmol/g. And (3) adding 50g (dry weight is 0.25g) of glyoxal polyacrylamide solution with the concentration of 0.5 wt% and 0.5g of epichlorohydrin into the chitosan solution in sequence, and stirring respectively to mix uniformly to obtain a cationic chitosan solution I. Adding 1g of nano silver particles into the sodium alginate solution, and stirring to uniformly mix to obtain the anionic sodium alginate solution I. Dropping a sodium alginate solution I into the bottom of a spinning pipe with the diameter of 50mm, and then dropping a chitosan solution I; the interface layers were then drawn upwards at a draw speed of 50cm/min to obtain wet fiber filaments, the drawing operation being shown in FIG. 6. And (3) putting the wet fiber filament into an oven at 80 ℃, and drying for 15min to obtain the high-strength water-resistant antibacterial composite fiber filament, wherein the substance is shown in fig. 7.

Comparative example 3:

the chitosan/sodium alginate composite fiber filament is prepared by the method under the condition of not adding a dry strength agent (glyoxal polyacrylamide) and a wet strength agent (epichlorohydrin).

It was measured that the diameter of the antibacterial composite fiber filament prepared in example 3 was 20 μm, and the diameter of the composite fiber filament prepared in comparative example 3 was 18 μm. The dry strength and the wet strength of the magnetic composite fiber filament obtained in example 3 were 275MPa and 70MPa, respectively, as measured by a universal tensile machine, while the dry strength and the wet strength of the composite fiber filament obtained in comparative example 3 were 55MPa and 10MPa, respectively. This shows that the dry strength of the magnetic composite fiber filaments prepared by the method described in the present application is improved by 5 times and the wet strength is improved by 7 times compared to the composite fiber filaments prepared by the prior art. Further, two-dimensional wide-angle X-ray diffraction analysis was performed, and the results are shown in FIG. 8. As can be seen from fig. 8A, the antibacterial composite fiber filament prepared in example 3 has an obvious core-shell structure; the half-width of the intensity distribution curve of the strongest ring on the equator (fig. 8B) was taken, and the degree of orientation of the composite filaments was calculated to be 0.7 based on eq.1. In addition, the composite fiber filament has obvious antibacterial property on escherichia coli and staphylococcus aureus.

Example 4:

adding 100g of cationic starch into a proper amount of water to prepare a solution with the concentration of 0.8 wt%; 100g of lignosulfonate was added to an appropriate amount of water to prepare a 0.6 wt% solution. Wherein the charge density of the cationic starch is 1.2mmol/g, and the charge density of the lignosulfonate is 2.4 mmol/g. And adding 1.0g of polyethyleneimine into the cationic starch solution, and stirring to uniformly mix to obtain the cationic starch solution I. Adding 125g (dry weight is 2.5g) of polyvinyl alcohol solution with the concentration of 2wt% into the anionic starch solution, stirring to mix uniformly, adding 10g of polyaniline, and stirring to mix uniformly to obtain the anionic starch solution I. And dropping an anionic starch solution I at the bottom of a spinning pipe with the diameter of 15mm, then dropping a cationic starch solution I, and upwards drawing the two interface layers at the drawing speed of 80cm/min to obtain wet fiber filaments. And (3) drying the wet fiber filaments in an oven at 60 ℃ for 50min to obtain the high-strength and water-resistant conductive composite fiber filaments.

Comparative example 4:

the cationic starch/lignosulfonate composite fiber filament is prepared by the method under the condition that a dry strength agent (polyvinyl alcohol) and a wet strength agent (polyethyleneimine) are not added.

The fiber filaments were analyzed using a scanning electron microscope, as shown in fig. 9. It was measured that the diameter of the conductive composite fiber filament prepared in example 4 was 35 μm, and the diameter of the composite fiber filament prepared in comparative example 4 was 31 μm. Meanwhile, the results carried out by using a universal tensile machine show that the dry strength and the wet strength of the conductive composite fiber filament prepared in the example 4 are 550MPa and 42MPa respectively; while the dry strength of the composite fiber filament obtained in comparative example 4 was 275MPa and the wet strength was 8 MPa. This shows that the dry strength of the conductive composite fiber filaments prepared by the method of the present application is improved by 2 times and the wet strength is improved by 5 times compared with the composite fiber filaments prepared by the prior art. Two-dimensional wide-angle X-ray diffraction analysis shows that the conductive composite fiber filament prepared in example 4 has an obvious core-shell structure, the full width at half maximum of the intensity distribution curve of the strongest ring on the equator is taken, and the orientation degree of the composite filament is calculated to be 0.65 according to eq.1. In addition, the conductive composite fiber filament was tested for conductivity using a resistance box.

Example 5:

adding 100g of cationic guar gum into a proper amount of water to prepare a solution with the concentration of 0.7 wt; 100g of carboxymethyl cellulose was added to an appropriate amount of water to prepare a 1.0% solution. Wherein the charge density of the cationic guar gum is 0.8mmol/g, and the charge density of the carboxymethyl cellulose is 1.7 mmol/g. Adding 5g (dry weight is 0.5g) of polyamide polyamine epichlorohydrin solution with the concentration of 10 wt% into the cationic guar gum solution, and stirring to uniformly mix to obtain the cationic guar gum solution. 50g (dry weight 5g) of polyvinyl alcohol solution with the concentration of 10 wt% and 20g of nano montmorillonite are sequentially added into the carboxymethyl cellulose solution, and the mixture is stirred and uniformly mixed to obtain carboxymethyl cellulose solution I. Dropping carboxymethyl cellulose solution at the bottom of a spinning pipe with the diameter of 10mm, then dropping cationic guar gum solution, and then upwards stretching the two interface layers at the stretching speed of 60cm/min to obtain wet fibers. And (3) drying the wet fiber in a 90 ℃ oven for 10min to obtain the high-strength and water-resistant flame-retardant composite fiber filament.

Comparative example 5:

the cationic guar gum/carboxymethyl cellulose composite fiber filament is prepared by the method under the condition that a dry strength agent (polyvinyl alcohol) and a wet strength agent (polyamide polyamine epichlorohydrin) are not added.

It was measured that the diameter of the flame-retardant conjugate fiber filament prepared in example 5 was 100 μm, and the diameter of the conjugate fiber filament prepared in comparative example 5 was 80 μm. Meanwhile, the results using a universal tensile machine showed that the flame-retardant composite fiber filament prepared in example 5 had a dry strength of 2000MPa and a wet strength of 300 MPa. While the composite fiber filament obtained in comparative example 5 had a dry strength of 500MPa and a wet strength of 38 MPa. This shows that the dry strength of the flame-retardant composite fiber filament prepared by the method of the present application is improved by 4 times and the wet strength is improved by 8 times compared with the composite fiber filament prepared by the prior art. Two-dimensional wide-angle X-ray diffraction analysis shows that the flame-retardant composite fiber filament prepared in example 5 has an obvious core-shell structure, the full width at half maximum of the intensity distribution curve of the strongest ring on the equator is taken, and the orientation degree of the composite filament is calculated to be 0.78 according to eq.1. In addition, the fiber filaments could not be ignited, i.e., had excellent flame retardant effect, as tested by the direct combustion method.

Example 6:

adding 100g of cationic guar gum into a proper amount of water to prepare a solution with the concentration of 1.2 wt%; 100g of sodium alginate is added into a proper amount of water to prepare a solution with the concentration of 0.4 wt%. Wherein the charge density of the cationic guar gum is 1.5mmol/g, and the charge density of the anionic nanocellulose is 0.5 mmol/g. And (3) sequentially adding 20g (dry weight 0.1g) of cationic polyacrylamide solution with the concentration of 0.5 wt% and 20g (dry weight 0.4g) of urea resin solution with the concentration of 2wt% into the cationic guar gum solution, and stirring to uniformly mix to obtain the cationic guar gum solution I. Adding 2g of calcium carbonate powder into the sodium alginate solution, and stirring to uniformly mix to obtain a sodium alginate solution I. Dropping a sodium alginate solution at the bottom of a spinning pipe with the diameter of 5mm, then dropping a cationic guar gum solution, and then upwards stretching the two interface layers at the stretching speed of 90cm/min to obtain the wet fiber. And (3) drying the wet fiber in a 70 ℃ oven for 50min to obtain the high-strength and water-resistant flame-retardant composite fiber filament.

Comparative example 6:

the cationic guar gum/sodium alginate composite fiber filament is prepared by the method under the condition that no dry strength agent (polyacrylamide) or wet strength agent (urea-formaldehyde resin) is added.

It was measured that the diameter of the flame-retardant conjugate fiber filament prepared in example 6 was 15 μm, and the diameter of the conjugate fiber filament prepared in comparative example 6 was 18 μm. Meanwhile, the results using a universal tensile machine showed that the flame-retardant conjugate fiber filament prepared in example 6 had a dry strength of 180MPa and a wet strength of 31MPa, respectively, while the conjugate fiber filament obtained in comparative example 6 had a dry strength of 60MPa and a wet strength of 16 MPa. This shows that the dry strength of the flame-retardant composite fiber filament prepared by the method of the present application is improved by 3 times and the wet strength is improved by 2 times compared with the composite fiber filament prepared by the prior art. By two-dimensional wide-angle X-ray diffraction analysis, the flame-retardant composite fiber filament prepared in example 6 has an obvious core-shell structure, and the half-height width of the intensity distribution curve of the strongest ring on the equator is calculated according to eq.1 to obtain the orientation degree of the composite filament of 0.6.

Example 7:

adding 100g of cationic nanocellulose into a proper amount of water to prepare a dispersion liquid with the concentration of 0.5 wt%; 100g of anionic lignin (lignosulfonate) was added to an appropriate amount of water to prepare a 1.0 wt% solution. Wherein the charge density of the cationic nanocellulose is 2.0mmol/g, and the charge density of the anionic lignin is 2.5 mmol/g. 80g (dry weight: 0.4g) of glyoxal polyacrylamide solution with the concentration of 0.5 wt% and 20g (dry weight: 1g) of polyethyleneimine solution with the concentration of 5% are sequentially added into the cationic nanocellulose dispersion liquid, and the mixture is stirred and uniformly mixed to obtain the cationic nanocellulose dispersion liquid I. And adding 15g of ferroferric oxide nano particles into the anionic lignin solution, and stirring to uniformly mix to obtain the anionic lignin solution I. And (2) connecting the anionic lignin solution into a core layer channel of a coaxial spinning machine, connecting the cationic nano-cellulose dispersion liquid into a shell layer channel of the spinning machine, stretching and fixing the two initial interfacial viscous barriers on an electric reel provided with an infrared dryer, and spinning at the speed of 100cm/min through a flow controller to obtain the high-strength and water-resistant magnetic composite fiber filament, wherein the substance is shown in figure 10. The diameter of the magnetic composite fiber filament was measured to be 80 μm. Meanwhile, the results of the universal tensile machine show that the dry strength of the composite fiber filament is 740MPa, and the wet strength of the composite fiber filament is 180MPa respectively. By adopting two-dimensional wide-angle X-ray diffraction analysis, the magnetic composite fiber filament has an obvious core-shell structure, and the orientation degree of the composite fiber filament is 0.75 obtained by Eq.1 calculation.

Comparative example 7:

under the condition of not adding a dry strength agent (glyoxal polyacrylamide) and a wet strength agent (polyethyleneimine), the cationic nanocellulose/anionic lignin composite fiber filament cannot be prepared by the spinning machine through the method. This is mainly due to the poor strength of the filaments, which cannot be collected.

In conclusion, the composite fiber filament prepared by the method has dry strength of 150-2000MPa and wet strength of 30-300MPa, and is remarkably improved compared with the prior art, so that the fiber filament has wide practical application prospect and great economic benefit. The core-shell structure is combined, the fiber filament with the functions of magnetism, antibacterial property, fire resistance or electric conduction can be prepared, and the fiber filament has wide application prospect in high added value fields of response devices, electromagnetic shielding, medical supplies and the like. In addition, the preparation method is simple to operate and low in cost, and can be used for automatic continuous spinning, so that the spinning efficiency is improved, and the industrial application prospect is further improved.

Claims

1. The preparation method of the composite functional filament with the core-shell structure is characterized by comprising the following steps: the method comprises the following steps:

(1) preparation of aqueous polymer solution/dispersion: weighing 100 parts by weight of each of the anionic polymer and the cationic polymer, respectively adding the anionic polymer and the cationic polymer into a proper amount of water, and uniformly stirring to obtain 0.1-1.2wt% of anionic polymer aqueous solution/dispersion and cationic polymer aqueous solution/dispersion;

(2) preparation of aqueous polymer solution/dispersion for drawing I: adding a proper auxiliary agent into the anionic polymer aqueous solution/dispersion liquid or the cationic polymer aqueous solution/dispersion liquid prepared in the step (1), and stirring until the mixture is uniformly mixed to obtain an anionic polymer aqueous solution/dispersion liquid I and a cationic polymer aqueous solution/dispersion liquid I; the auxiliary agent comprises 0.1-5 parts by weight of dry strength agent, 0.1-5 parts by weight of wet strength agent and 1-20 parts by weight of functional material; the aqueous solution/dispersion of the assistant is uncharged or has the same charge as the aqueous solution/dispersion of the polymer to be added;

(3) preparing functional composite fiber filaments: firstly, adding the anionic polymer solution/dispersion solution I prepared in the step (2) into the bottom of a spinning pipe, then slowly adding the cationic polymer solution/dispersion solution I prepared in the step (2), stretching the interface layer to obtain wet fiber filaments, and drying to obtain the high-strength and water-resistant composite functional filaments.

2. The method for preparing a composite functional filament with a core-shell structure according to claim 1, wherein the method comprises the following steps: the charge density of the anionic polymer and the charge density of the cationic polymer are both 0.5 to 3.0 mmol/g; the anionic polymer is a bio-based natural anionic polymer, and the cationic polymer is a bio-based natural cationic polymer.

3. The method for preparing a composite functional filament with a core-shell structure according to claim 2, wherein the method comprises the following steps: the anionic polymer is one or more of anionic guar gum, anionic starch, sodium alginate, anionic cellulose and anionic lignin, and the cationic polymer is one or more of cationic guar gum, cationic starch, chitosan and cationic cellulose.

4. The method for preparing a composite functional filament with a core-shell structure according to claim 2, wherein the method comprises the following steps: the specific adding method of the auxiliary agent in the step (2) comprises the following steps: the additives added to the same polymer solution should be added sequentially and stirred well to avoid agglomeration.

5. The method for preparing a composite functional filament with a core-shell structure according to claim 2, wherein the method comprises the following steps: the dry strength agent in the step (2) is one or more of polyacrylamide, glyoxal polyacrylamide, polyvinyl alcohol and the like, and the wet strength agent is one or more of epichlorohydrin, polyamide polyamine epichlorohydrin, urea-formaldehyde resin, melamine formaldehyde resin and polyethyleneimine.

6. The method for preparing a composite functional filament with a core-shell structure according to claim 2, wherein the method comprises the following steps: the functional material in the step (2) is one or more of borax, nano montmorillonite, calcium carbonate powder, ferroferric oxide nano particles, polyaniline and nano silver particles.

7. The method for preparing a composite functional filament with a core-shell structure according to any one of claims 1 to 6, wherein: the diameter of the spinning pipe in the step (3) is 5-50mm, and the spinning and stretching speed is 50-100 cm/min; the drying specifically comprises the following steps: drying at 50-105 deg.C for 5-60 min.

8. A composite functional filament produced by the method according to any one of claims 1 to 7, wherein: the composite functional filament is of a core-shell structure, and the core-shell structure comprises a core layer and a shell layer coated on the outer side of the core layer; the shell layer is made of cationic polymer, and the core layer is made of anionic polymer.

9. A composite functional filament according to claim 8, characterized in that: the diameter of the composite functional filament is 10-100 μm, and the orientation degree of the composite fiber is 0.6-0.8.

10. A composite functional filament according to claim 8 or 9, characterized in that: the dry strength of the composite functional filament is 150-2000MPa, and the wet strength is 30-300 MPa.