Preparation process of anti-static polylactic acid ultrafine fiber fabric

Abstract

The application relates to the technical field of polylactic acid fibers, and discloses a preparation process of an anti-static polylactic acid superfine fiber fabric, which is prepared from tetra (hydroxymethyl) phosphonium chloride, 2-amino-4, 6-dimethoxy-1, 3, 5-triazine and the like as raw materials, star-shaped polylactic acid grafted carbon nanotubes are prepared, and are melt spun with polylactic acid chips to obtain the polylactic acid superfine fiber fabric; the star-shaped polylactic acid grafted carbon nanotubes have a structure similar to that of the polylactic acid matrix, the carbon nanotubes are uniformly dispersed in the polymer matrix and form a strong interface combination, migration and precipitation are avoided, and the anti-static durability is good; nitrogen and phosphorus synergistic flame-retardant elements are contained in the structure, the exchange of the fiber matrix with oxygen and heat in the air can be blocked, the flame-retardant performance of the superfine fiber fabric is improved; the formed crosslinked network structure can increase the compactness of the fiber fabric, and the mechanical performance of the superfine fiber fabric is significantly improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of polylactic acid fibers, in particular to a preparation process of an anti-static polylactic acid superfine fiber fabric. BACKGROUND

[0002] The polylactic acid superfine fiber fabric is a new type of fabric based on sustainable biomass raw materials, has biodegradability and excellent physical properties, and has a broader application prospect as people pay more and more attention to environmental protection and health; due to the extremely small fiber diameter of the polylactic acid superfine fiber fabric, the polylactic acid superfine fiber fabric has extremely high specific surface area and excellent softness, air permeability, moisture absorption and other properties, so that the polylactic acid superfine fiber fabric has a wide application prospect in the fields of clothes, bedding, sanitary products and the like; however, in relatively dry seasons and seasons lacking air circulation, the polylactic acid fiber fabric is prone to static electricity, which affects the comfort of wearing, causes the fabric to easily adsorb dust or hair, and in addition, static electricity can also cause spark discharge, causing fire hazards and the like, so that improving the anti-static and flame-retardant properties of the polylactic acid fiber fabric has become a research hotspot at present.

[0003] In the prior art, in order to avoid the static problem of the fiber fabric, some anti-static washing liquid or anti-static spray is generally used, which is mostly coated on the outer layer, has poor heat resistance and durability, is harmful to the skin, and is lost and invalid quickly under the application conditions such as friction and washing, and is not suitable for use on the polylactic acid fiber fabric; patent No. CN115058789B discloses a preparation method of a flexible anti-static polylactic acid fiber, an anti-static agent is added to polylactic acid in a prepolymerization stage with low molecular weight and low viscosity, the polylactic acid fiber is given good anti-static performance, compared with the process of adding an anti-static agent to polylactic acid chips, the energy consumption is greatly reduced, and the production cost is reduced, but the added anti-static agent still has poor compatibility with the polylactic acid matrix, and the added anti-static agent is a small molecule anti-static agent, which is easy to migrate and precipitate, and the anti-static durability needs to be further enhanced.

[0004] The carbon nanotube has a hollow tubular structure, a large specific surface area, strong adsorption capacity and excellent conductivity, but the interface bonding force between the carbon nanotube and the polylactic acid matrix is poor, and the carbon nanotube is not uniformly dispersed, which often causes the mechanical properties and processing properties to decrease; meanwhile, the polylactic acid itself has poor toughness, low impact resistance and poor filling fluidity, which limits the application of the polylactic acid in fiber fabrics; the application aims to synthesize a star-shaped polylactic acid with flame-retardant properties to modify the surface of the carbon nanotube, improve the easy agglomeration of the carbon nanotube in the polylactic acid matrix, make the carbon nanotube uniformly dispersed in the polymer matrix and form a strong interface bonding, fully play the toughening and reinforcing role, avoid migration and precipitation, have anti-static durability and good flame-retardant properties. SUMMARY

[0005] Therefore, the application aims to provide a preparation process of an anti-static polylactic acid superfine fiber fabric, and a polylactic acid fiber fabric with good anti-static performance and good flame retardance is prepared, and the application range of the polylactic acid fiber fabric is widened.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] A preparation process of an anti-static polylactic acid superfine fiber fabric is performed according to the following steps.

[0008] Step (1), under a nitrogen atmosphere, six-arm star phosphorus-nitrogen-based polylactic acid and N,N-dimethylacetamide are added into a reaction flask, stirred uniformly, acyl chloride carbon nanotubes and pyridine are added, and reaction is performed at 115-130 DEG C for 24-48 h, cooled to room temperature, filtered by a microporous filter, washed by methanol, and dried to obtain star polylactic acid grafted carbon nanotubes.

[0009] Step (2), polylactic acid dry chips and star polylactic acid grafted carbon nanotubes are placed in a Haake torque rheometer, melt blended at a temperature of 175-190 DEG C and a rotation speed of 40-60 r / min for 5-10 min, added into a spinning machine, extruded into a shape through a spinning assembly and a spinneret, and then cooled, oiled, stretched, and wound to obtain an anti-static polylactic acid superfine fiber fabric.

[0010] Preferably, in step (1), the ratio of the six-arm star phosphorus-nitrogen-based polylactic acid, the acyl chloride carbon nanotubes, and the pyridine is 100 g:(25-40) g:(18-25) g.

[0011] Preferably, in step (2), the ratio of the polylactic acid dry chips and the star polylactic acid grafted carbon nanotubes is 100 g:(2-10) g.

[0012] Preferably, in step (2), the temperature of each zone of the spinning machine is 180-200 DEG C, the spinning speed is 750-1000 m / min, and the stretching temperature is 80-90 DEG C.

[0013] Preferably, in step (1), the preparation process of the six-arm star phosphorus-nitrogen-based polylactic acid is performed according to the following steps.

[0014] Step S1, under a nitrogen atmosphere, tetra(hydroxymethyl)phosphonium chloride and ethanol are added into a reaction flask, stirred uniformly, 2-amino-4,6-dimethoxy-1,3,5-triazine is added, stirred and reacted, after the reaction is completed, precipitated, filtered, washed by ethanol, and dried to obtain a tetra(triazine dimethoxy) phosphorus intermediate.

[0015] Step S2, under the atmosphere of nitrogen, the reaction flask is added with tetra (triazine dimethoxy) phosphorus intermediate and dichloromethane, after stirring, boron tribromide is added, the reaction is carried out at 0-20℃ for 16-32h, methanol is added for quenching, ethyl acetate and deionized water are extracted, the organic phase is concentrated, dried to obtain the hexahydroxy phosphorus nitrogen intermediate.

[0016] Step S3, under the atmosphere of nitrogen, the reaction kettle is added with lactide, hexahydroxy phosphorus nitrogen intermediate and stannous octoate, nitrogen is extracted to vacuum, the reaction is carried out at 140-160℃ for 12-24h, after the reaction, chloroform is added for dissolution, then methanol is added for precipitation, filtration, ethanol washing and drying are carried out to obtain the six-armed star phosphorus nitrogen based polylactic acid.

[0017] Preferably, the ratio of tetra (hydroxymethyl) phosphorus chloride and 2-amino-4, 6-dimethoxy-1, 3, 5-triazine in step S1 is 1mol: (4.1-4.5) mol.

[0018] Preferably, the reaction temperature in step S1 is 20-35℃, and the reaction time is 2-5h.

[0019] Preferably, the ratio of tetra (triazine dimethoxy) phosphorus intermediate and boron tribromide in step S2 is 1mol: (6.5-8) mol.

[0020] Preferably, the lactide in step S3 is any one of D-lactide, L-lactide or D, L-lactide.

[0021] Preferably, the ratio of lactide, hexahydroxy phosphorus nitrogen intermediate and stannous octoate in step S3 is 1mol: (0.15-0.25) mol: (0.02-0.05) mol.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) Carbon nanotubes have a large aspect ratio and a large number of π bonds, and electrons can move through the π bonds to form an electric current, forming a partial conduction path inside the fiber. As the content of carbon nanotubes increases, a perfect conductive network structure is gradually formed. At the same time, carbon nanotubes are also lubricants, which have a certain lubricity on the surface of the fiber, can reduce the friction coefficient, and thus inhibit and reduce the generation of static electricity. The star polylactic acid grafted carbon nanotubes have a similar structure to the polylactic acid matrix, have good interface compatibility, make the carbon nanotubes uniformly dispersed in the polymer matrix and form a strong interface combination, avoid migration and precipitation, and have long-lasting anti-static performance.

[0024] (2) Star-shaped polylactic acid grafted carbon nanotubes contain triazine rings, which will decompose to produce inert gas when heated, diluting the concentration of oxygen and flammable gas in the air, while having excellent carbon formation capacity. When the material is subjected to fire roasting, a protective layer similar to foam is formed, isolating the fire source from the material, thereby slowing or preventing the spread of the flame. In addition, phosphorus-containing substances decompose to generate phosphoric acid or polyphosphoric acid when burning, forming a dense carbon layer to isolate the substrate from heat and oxygen in solid form. Phosphorus and nitrogen elements synergistically flame retard, further crosslinking into a more dense carbon layer during combustion, blocking the exchange of oxygen and heat in the air with the fiber matrix, significantly improving the flame retardant performance of the ultra-fine fiber fabric.

[0025] (3) Carbon nanotubes can be chemically grafted with multi-armed polylactic acid, making them uniformly dispersed in the polylactic acid matrix, improving the interaction between the composite materials, forming a cross-linked network structure, and increasing the density of the fiber fabric. At the same time, the specific surface area of carbon nanotubes is large, which increases the contact area between the matrix and provides a guarantee for physical entanglement, thereby significantly improving the mechanical properties of the ultra-fine fiber fabric and expanding its application range. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described below in conjunction with specific examples. Obviously, the described examples are only a part of the examples of the present application, not all examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] Unless otherwise specified, the raw materials and reagents used in this application are commercially available or can be prepared by known methods.

[0028] Preparation of acyl chloride carbon nanotubes: 1 g of carbon nanotubes was placed in a mixture of 120 mL of sulfuric acid and concentrated nitric acid (volume ratio of 3:1), ultrasonic oscillation at room temperature for 30 min, stirring at 80°C oil bath for 4 h, then diluted with 2 L of deionized water, filtered and washed to neutral with a microporous membrane, and dried at 70°C under vacuum for 24 h to obtain carboxylated carbon nanotubes; 1 g of carbon nanotubes was added to 100 mL of thionyl chloride, ultrasonic oscillation for 15 min, then 2-3 mL of N,N-dimethylformamide was added as a catalyst, and the reaction was carried out at 70°C oil bath for 48 h. The remaining thionyl chloride was removed by reduced pressure distillation, and the product was washed with tetrahydrofuran and dried to obtain acyl chloride carbon nanotubes.

[0029] Tetrakis(hydroxymethyl)phosphonium chloride, CAS number 124-64-1.

[0030] 2-amino-4,6-dimethoxy-1,3,5-triazine, CAS number 3140-73-6. EXAMPLE

[0031] (1) Under the atmosphere of nitrogen, 45 mmol of tetrakis(hydroxymethyl)phosphonium chloride and 270 mL of ethanol were added into a reaction flask, stirred uniformly, 190 mmol of 2-amino-4,6-dimethoxy-1,3,5-triazine was added, reacted at 25℃ for 4 h, precipitated, filtered, washed with ethanol, and dried to obtain a tetrakis(triazine dimethoxy) phosphorus intermediate.

[0032] (2) Under the atmosphere of nitrogen, 42 mmol of the tetrakis(triazine dimethoxy) phosphorus intermediate and 605 mL of dichloromethane were added into a reaction flask, stirred uniformly, 315 mmol of boron tribromide was added, reacted at 5℃ for 24 h, methanol was added for quenching, extracted with ethyl acetate and deionized water, the organic phase was concentrated and dried to obtain a hexahydroxyl phosphorus nitrogen intermediate.

[0033] (3) Under the atmosphere of nitrogen, 35 mmol of D-lactide, 7 mmol of the hexahydroxyl phosphorus nitrogen intermediate and 1.4 mmol of stannous octoate were added into a reaction kettle, vacuumed by nitrogen, reacted at 150℃ for 18 h, after the reaction, chloroform was added for dissolution, then methanol was added for precipitation, filtered, washed with ethanol, and dried to obtain a six-armed star phosphorus nitrogen-based polylactic acid. The preparation reaction formula is as follows:

[0034]

[0035] (4) Under the atmosphere of nitrogen, 10 g of the six-armed star phosphorus nitrogen-based polylactic acid and 45 mL of N,N-dimethylacetamide were added into a reaction flask, stirred uniformly, 2.5 g of acyl chloride carbon nanotubes and 2.2 g of pyridine were added, reacted at 120℃ for 32 h, cooled to room temperature, filtered by a microporous filter, washed with methanol, and dried to obtain a star polylactic acid grafted carbon nanotube.

[0036] (5) 100 g of polylactic acid dry chips and 2 g of the star polylactic acid grafted carbon nanotube were placed in a Haake torque rheometer, melt blended at a temperature of 185℃ and a rotation speed of 50 r / min for 8 min, added into a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine was 190℃, the spinning speed was 900 m / min, the stretching temperature was 85℃, and then cooled, oiled, stretched, and wound to obtain an antistatic polylactic acid ultrafine fiber fabric. Example

[0037] (1) Under the atmosphere of nitrogen, 120 mmol of tetrakis(hydroxymethyl)phosphonium chloride and 600 mL of ethanol were added into a reaction flask, stirred uniformly, 492 mmol of 2-amino-4,6-dimethoxy-1,3,5-triazine was added, reacted at 35℃ for 2 h, precipitated, filtered, washed with ethanol, and dried to obtain a tetrakis(triazine dimethoxy) phosphorus intermediate.

[0038] (2) Under the atmosphere of nitrogen, 105 mmol of tetra (triazine dimethoxy) phosphorus intermediate and 1050 mL of dichloromethane were added into a reaction flask, stirred uniformly, then 682.5 mmol of boron tribromide was added, reacted at 20℃ for 16 h, methanol was added for quenching, extracted with ethyl acetate and deionized water, the organic phase was concentrated and dried to obtain a hexahydroxy phosphorus nitrogen intermediate.

[0039] (3) Under the atmosphere of nitrogen, 90 mmol of L-lactide, 13.5 mmol of hexahydroxy phosphorus nitrogen intermediate and 1.8 mmol of stannous octoate were added into a reaction kettle, vacuumed by nitrogen, reacted at 160℃ for 12 h, then cooled, dissolved with chloroform, precipitated with methanol, filtered, washed with ethanol and dried to obtain a six-armed star phosphorus nitrogen-based polylactic acid.

[0040] (4) Under the atmosphere of nitrogen, 10 g of six-armed star phosphorus nitrogen-based polylactic acid and 40 mL of N,N-dimethylacetamide were added into a reaction flask, stirred uniformly, then 2.9 g of acyl chloride carbon nanotube and 1.8 g of pyridine were added, reacted at 130℃ for 24 h, cooled to room temperature, filtered with a microporous filter, washed with methanol and dried to obtain a star polylactic acid grafted carbon nanotube.

[0041] (5) 100 g of polylactic acid dry chip and 4 g of star polylactic acid grafted carbon nanotube were placed in a Haake torque rheometer, melt blended at a temperature of 190℃ and a rotation speed of 60 r / min for 5 min, then added into a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine was 200℃, the spinning speed was 1000 m / min, the stretching temperature was 90℃, then cooled, oiled, stretched and wound to obtain an antistatic polylactic acid ultrafine fiber fabric. Example

[0042] (1) Under the atmosphere of nitrogen, 65 mmol of tetra (hydroxymethyl) phosphorus chloride and 520 mL of ethanol were added into a reaction flask, stirred uniformly, then 292.5 mmol of 2-amino-4,6-dimethoxy-1,3,5-triazine was added, reacted at 20℃ for 5 h, precipitated, filtered, washed with ethanol and dried to obtain a tetra (triazine dimethoxy) phosphorus intermediate.

[0043] (2) Under the atmosphere of nitrogen, 60 mmol of tetra (triazine dimethoxy) phosphorus intermediate and 900 mL of dichloromethane were added into a reaction flask, stirred uniformly, then 480 mmol of boron tribromide was added, reacted at 0℃ for 32 h, methanol was added for quenching, extracted with ethyl acetate and deionized water, the organic phase was concentrated and dried to obtain a hexahydroxy phosphorus nitrogen intermediate.

[0044] (3) Under the atmosphere of nitrogen, 50 mmol of D, L-lactide, 12.5 mmol of hexahydroxyl phosphorus nitrogen intermediate and 2.5 mmol of stannous octoate were added into a reaction kettle, vacuumized by nitrogen, reacted at 140℃ for 24 h, after reaction, cooled, chloroform was added for dissolution, then methanol was added for precipitation, filtered, washed with ethanol, dried, to obtain a six-armed star phosphorus nitrogen-based polylactic acid.

[0045] (4) Under the atmosphere of nitrogen, 10 g of six-armed star phosphorus nitrogen-based polylactic acid and 55 mL of N, N-dimethylacetamide were added into a reaction flask, stirred uniformly, then 3.3 g of acyl chloride carbon nanotube and 2.5 g of pyridine were added, reacted at 115℃ for 48 h, cooled to room temperature, filtered by a microporous filter, washed with methanol, dried to obtain a star polylactic acid grafted carbon nanotube.

[0046] (5) 100 g of polylactic acid dry chip and 6 g of star polylactic acid grafted carbon nanotube were placed in a Haake torque rheometer, melt blended at 175℃ and a rotation speed of 40 r / min for 10 min, added into a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine was 180℃, the spinning speed was 750 m / min, the stretching temperature was 80℃, then cooled, oiled, stretched, and wound, to obtain an anti-static polylactic acid ultrafine fiber fabric. EMBODIMENT

[0047] (1) Under the atmosphere of nitrogen, 80 mmol of tetra (hydroxymethyl) phosphonium chloride and 550 mL of ethanol were added into a reaction flask, stirred uniformly, then 340 mmol of 2-amino-4, 6-dimethoxy-1, 3, 5-triazine was added, reacted at 30℃ for 4 h, precipitated, filtered, washed with ethanol, dried to obtain a tetra (triazine dimethoxy) phosphorus intermediate.

[0048] (2) Under the atmosphere of nitrogen, 72 mmol of tetra (triazine dimethoxy) phosphorus intermediate and 900 mL of dichloromethane were added into a reaction flask, stirred uniformly, then 540 mmol of boron tribromide was added, reacted at 15℃ for 20 h, quenched by adding methanol, extracted with ethyl acetate and deionized water, the organic phase was concentrated and dried to obtain a hexahydroxyl phosphorus nitrogen intermediate.

[0049] (3) Under the atmosphere of nitrogen, 65 mmol of D-lactide, 15.6 mmol of hexahydroxyl phosphorus nitrogen intermediate and 2.48 mmol of stannous octoate were added into a reaction kettle, vacuumized by nitrogen, reacted at 155℃ for 22 h, after reaction, cooled, chloroform was added for dissolution, then methanol was added for precipitation, filtered, washed with ethanol, dried, to obtain a six-armed star phosphorus nitrogen-based polylactic acid.

[0050] (4) Under nitrogen atmosphere, 10 g of six-armed star phosphorus-nitrogen-based polylactic acid and 45 mL of N, N-dimethylacetamide were added into a reaction flask, stirred uniformly, 3.7 g of acyl chloride carbon nanotube and 2 g of pyridine were added, reacted at 120℃ for 36 h, cooled to room temperature, filtered with a microporous filter, washed with methanol, and dried to obtain star polylactic acid grafted carbon nanotube.

[0051] (5) 100 g of polylactic acid dry chip and 8 g of star polylactic acid grafted carbon nanotube were placed in a Hake torque rheometer, melt blended at 180℃ and 55 r / min for 8 min, added into a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine was 185℃, the spinning speed was 800 m / min, the stretching temperature was 90℃, and then cooled, oiled, stretched, and wound to obtain an anti-static polylactic acid ultrafine fiber fabric. EMBODIMENT

[0052] (1) Under nitrogen atmosphere, 30 mmol of tetrakis (hydroxymethyl) phosphonium chloride and 220 mL of ethanol were added into a reaction flask, stirred uniformly, 130.5 mmol of 2-amino-4, 6-dimethoxy-1, 3, 5-triazine was added, reacted at 35℃ for 5 h, precipitated, filtered, washed with ethanol, and dried to obtain a tetrakis (triazine dimethoxy) phosphorus intermediate.

[0053] (2) Under nitrogen atmosphere, 25 mmol of tetrakis (triazine dimethoxy) phosphorus intermediate and 350 mL of dichloromethane were added into a reaction flask, stirred uniformly, 180 mmol of boron tribromide was added, reacted at 5℃ for 24 h, quenched with methanol, extracted with ethyl acetate and deionized water, the organic phase was concentrated and dried to obtain a six-hydroxyl phosphorus-nitrogen intermediate.

[0054] (3) Under nitrogen atmosphere, 20 mmol of L-lactide, 3.6 mmol of six-hydroxyl phosphorus-nitrogen intermediate and 0.7 mmol of stannous octoate were added into a reaction kettle, vacuumed to vacuum, reacted at 160℃ for 24 h, cooled after reaction, dissolved with chloroform, then precipitated with methanol, filtered, washed with ethanol, and dried to obtain six-armed star phosphorus-nitrogen-based polylactic acid.

[0055] (4) Under nitrogen atmosphere, 10 g of six-armed star phosphorus-nitrogen-based polylactic acid and 48 mL of N, N-dimethylacetamide were added into a reaction flask, stirred uniformly, 4 g of acyl chloride carbon nanotube and 2.4 g of pyridine were added, reacted at 130℃ for 48 h, cooled to room temperature, filtered with a microporous filter, washed with methanol, and dried to obtain star polylactic acid grafted carbon nanotube.

[0056] (5) 100 g of polylactic acid dry chips and 10 g of star-shaped polylactic acid grafted carbon nanotubes are placed in a Haake torque rheometer, and melt blended at a temperature of 190°C and a rotation speed of 50 r / min for 10 min, and then added to a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine is 195°C, the spinning speed is 950 m / min, and the stretching temperature is 85°C, and then cooled, oiled, stretched, and wound to obtain an anti-static polylactic acid ultrafine fiber fabric.

[0057] Comparative Example 1

[0058] (1) 35 mmol of D-lactide, 7 mmol of dipentaerythritol (with a structural formula of , and 1.4 mmol of stannous octoate are added to a reaction kettle under a nitrogen atmosphere, vacuumed, and reacted at 150°C for 18 h. After the reaction, chloroform is added for dissolution, and then methanol is added for precipitation. After filtration, ethanol washing and drying, a six-armed star-shaped polylactic acid is obtained.

[0059] (2) 10 g of the six-armed star-shaped polylactic acid and 45 mL of N,N-dimethylacetamide are added to a reaction flask under a nitrogen atmosphere, stirred uniformly, and then 2.5 g of acyl chloride carbon nanotubes and 2.2 g of pyridine are added. The mixture is reacted at 120°C for 32 h, cooled to room temperature, filtered with a microporous filter, washed with methanol, and dried to obtain star-shaped polylactic acid grafted carbon nanotubes.

[0060] (3) 100 g of polylactic acid dry chips and 2 g of star-shaped polylactic acid grafted carbon nanotubes are placed in a Haake torque rheometer, and melt blended at a temperature of 185°C and a rotation speed of 50 r / min for 8 min, and then added to a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine is 190°C, the spinning speed is 900 m / min, and the stretching temperature is 85°C, and then cooled, oiled, stretched, and wound to obtain a polylactic acid ultrafine fiber fabric.

[0061] Comparative Example 2

[0062] 100 g of polylactic acid dry chips and 2 g of six-armed star-shaped phosphorus-nitrogen-based polylactic acid (prepared by Example 1) are placed in a Haake torque rheometer, and melt blended at a temperature of 185°C and a rotation speed of 50 r / min for 8 min, and then added to a spinning machine, extruded into a shape through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine is 190°C, the spinning speed is 900 m / min, and the stretching temperature is 85°C, and then cooled, oiled, stretched, and wound to obtain a polylactic acid ultrafine fiber fabric.

[0063] Comparative Example 3

[0064] 100g polylactic acid dry chip and 2g carbon nanotube were placed in a Haake torque rheometer, melt blended at 185℃ and 50r / min for 8min, added to a spinning machine, extruded through a spinning assembly and a spinneret, wherein the temperature of each zone of the spinning machine was 190℃, the spinning speed was 900m / min, the drawing temperature was 85℃, then cooled, oiled, drawn, and wound to obtain a polylactic acid ultrafine fiber fabric.

[0065] Specific resistance test: the prepared polylactic acid ultrafine fiber fabric sample was cut into 30mm short fibers, rubbed into a fluffy state, and after equilibration for 48h under standard conditions, tested by a fiber specific resistance tester, 10 times for each sample, and the average value was taken.

[0066] Friction electrostatic voltage test: the prepared polylactic acid ultrafine fiber fabric sample was knitted into a 5cm×20cm knitted fabric by a hand knitting machine, and the induced static voltage of the fabric after friction was tested by a friction fabric static tester, 10 times for each sample, and the average value was taken.

[0067] Table 1 Anti-static performance test

[0068] Specific resistance x 10 -8 (Ω-cm) Tribo-triboelectric voltage (V) Example 1 8.96 988 Example 2 7.52 905 Example 3 5.84 824 Example 4 4.10 708 Example 5 3.88 670 Comparative Example 1 9.02 995 Comparative Example 2 18.35 1680 Comparative Example 3 14.21 1325

[0069] The specific resistance was used to characterize the anti-static performance of the fiber fabric, and the specific resistance decreased, the insulation of the fiber fabric decreased, the conductivity increased, and the anti-static performance improved. The induced static voltage after friction was used to characterize the anti-static performance of the fiber fabric, and the smaller the induced static voltage after friction, the better the anti-static performance of the fiber fabric. From the test results in the above table, it can be seen that with the increase of the content of star-shaped polylactic acid grafted carbon nanotube, the anti-static performance of the polylactic acid ultrafine fiber fabric gradually increased, and the specific resistance of example 4 was 4.10×10 -8 Ω·cm, the friction electrostatic voltage was 708V, and the anti-static performance was excellent; this was because on the one hand, carbon nanotubes had a large aspect ratio and a large number of π bonds, and electrons could move through the π bonds to form a current, forming a partial conduction path inside the fiber, and with the increase of the content of carbon nanotubes, a perfect conductive network structure was gradually formed; at the same time, carbon nanotubes were also lubricants, which had a certain lubricity on the fiber surface, could reduce the friction coefficient, and thus inhibit and reduce the generation of static charge; on the other hand, star-shaped polylactic acid grafted carbon nanotubes had a similar structure to the polylactic acid matrix, had good interface compatibility, made the carbon nanotubes uniformly dispersed in the polymer matrix and formed a strong interface bond, avoided migration and precipitation, and had a long-lasting anti-static performance.

[0070] In comparative example 1, there was no carbon nanotube, and no anti-static performance; in comparative example 3, the added carbon nanotubes were not modified, had poor compatibility with the polylactic acid matrix, were easy to agglomerate, and were difficult to form a good conductive path, so the anti-static performance was poor.

[0071] Flame retardant performance test: test according to GB / T 5455-2014 standard, and evaluate the flame retardant performance of superfine fiber fabric by after flame time and burn-off length.

[0072] Table 2 Flame retardant performance test

[0073] Afterglow time (s) Damage length (mm) Example 1 10.3 19.6 Example 2 8.2 17.2 Example 3 5.5 14.9 Example 4 3.1 11.5 Example 5 2.4 8.8 Comparative Example 1 38.5 52.7 Comparative Example 2 11.0 19.2 Comparative Example 3 42.8 55.4

[0074] From the above test results, it can be seen that with the increase of the content of star-shaped polylactic acid grafted carbon nanotubes, the flame retardant performance of polylactic acid superfine fiber fabric is gradually enhanced, the after flame time in Example 5 is only 2.4s, and the burn-off length is 8.8mm, and the flame retardant performance is good. This is because the star-shaped polylactic acid grafted carbon nanotubes contain triazine rings, which will decompose to produce inert gas when heated, dilute the oxygen and combustible gas concentration in the air, and at the same time have excellent carbon formation capacity. When the material is roasted by fire, a protective layer similar to foam is formed to isolate the fire source from the material, thereby slowing down or preventing the spread of the flame. In addition, phosphorus-containing substances decompose to generate phosphoric acid or polyphosphoric acid during combustion, and then form a dense carbon layer to isolate the substrate from heat and oxygen in the form of solid. Phosphorus and nitrogen elements synergistically flame retardant, further crosslinking into a more dense carbon layer during combustion, blocking the exchange of oxygen and heat in the air with the fiber matrix, significantly improving the flame retardant performance of the superfine fiber fabric. Comparative Example 1 and Comparative Example 3 do not contain phosphorus and nitrogen flame retardant elements and do not have flame retardant performance.

[0075] Mechanical property test: test by using electronic strength machine for chemical fiber filament, clamping distance 200mm, test 10 times for each sample, and take average value.

[0076] Table 3 Mechanical property test

[0077] Breaking strength (cN / dtex) Example 1 1.76 Example 2 1.81 Example 3 1.95 Example 4 2.06 Example 5 2.15 Comparative Example 1 1.72 Comparative Example 2 1.63 Comparative Example 3 1.48

[0078] From the above test results, it can be seen that with the increase of the content of star-shaped polylactic acid grafted carbon nanotubes, the mechanical properties of polylactic acid superfine fiber fabric are gradually enhanced, and the mechanical properties of polylactic acid superfine fiber fabric are gradually enhanced. The main reason is that the carbon nanotubes and the multi-arm polylactic acid are chemically grafted, which makes them uniformly dispersed in the polylactic acid matrix, improves the interaction between the composite materials, forms a crosslinked network structure, and increases the density of the fiber fabric. At the same time, the specific surface area of carbon nanotubes is large, which increases the contact area between the matrix and provides guarantee for physical entanglement, thereby significantly improving the mechanical properties of the superfine fiber fabric.

[0079] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, as long as it does not deviate from the technical solution of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A process for preparing an anti-static polylactic acid ultrafine fiber fabric, characterized in that, The preparation process is carried out according to the following steps: Step (1), under a nitrogen atmosphere, six-arm star phosphorus-nitrogen-based polylactic acid and N,N-dimethylacetamide are added to a reaction flask, stirred uniformly, then acyl chloride carbon nanotubes and pyridine are added, reacted at 115-130 DEG C for 24-48h, cooled to room temperature, filtered with a microporous filter, washed with methanol, dried to obtain star polylactic acid grafted carbon nanotubes; Step (2), polylactic acid dry chips and star polylactic acid grafted carbon nanotubes are placed in a Haake torque rheometer, melt blended at a temperature of 175-190 DEG C and a rotation speed of 40-60r / min for 5-10min, then a spinning machine is added, extruded into a shape through a spinning assembly and a spinneret, then cooled, oiled, stretched, and wound to obtain an anti-static polylactic acid ultrafine fiber fabric; The preparation process of the six-arm star phosphorus-nitrogen-based polylactic acid in step (1) is carried out according to the following steps: Step S1, under a nitrogen atmosphere, tetrakis (hydroxymethyl) phosphonium chloride and ethanol are added to a reaction flask, stirred uniformly, then 2-amino-4,6-dimethoxy-1,3,5-triazine is added, stirred and reacted, after the reaction is completed, the precipitate is allowed to settle, filtered, washed with ethanol, and dried to obtain a tetrakis (triazine dimethoxy) phosphorus intermediate; Step S2, under a nitrogen atmosphere, the tetrakis (triazine dimethoxy) phosphorus intermediate and dichloromethane are added to a reaction flask, stirred uniformly, then boron tribromide is added, reacted at 0-20 DEG C for 16-32h, quenched with methanol, extracted with ethyl acetate and deionized water, the organic phase is concentrated and dried to obtain a six-hydroxy phosphorus-nitrogen intermediate; Step S3, under a nitrogen atmosphere, lactide, the six-hydroxy phosphorus-nitrogen intermediate, and stannous octoate are added to a reaction kettle, vacuumed, reacted at 140-160 DEG C for 12-24h, then cooled, dissolved in chloroform, precipitated with methanol, filtered, washed with ethanol, and dried to obtain the six-arm star phosphorus-nitrogen-based polylactic acid.

2. The process for preparing an anti-static polylactic acid ultrafine fiber fabric according to claim 1, wherein the anti-static agent is added to the polylactic acid solution in an amount of 0.1 to 5% by weight. The ratio of the six-arm star phosphorus-nitrogen-based polylactic acid, acyl chloride carbon nanotubes, and pyridine in step (1) is 100g:(25-40)g:(18-25)g.

3. The process for preparing the anti-static polylactic acid ultrafine fiber fabric according to claim 1, characterized in that, The ratio of the polylactic acid dry chips and the star polylactic acid grafted carbon nanotubes in step (2) is 100g:(2-10)g.

4. The process for preparing the anti-static polylactic acid ultrafine fiber fabric according to claim 1, characterized in that, In step (2), the temperature of each zone of the spinning machine is 180-200 DEG C, the spinning speed is 750-1000m / min, and the stretching temperature is 80-90 DEG C.

5. The process for preparing the anti-static polylactic acid ultrafine fiber fabric according to claim 1, characterized in that, The ratio of tetrakis (hydroxymethyl) phosphonium chloride and 2-amino-4,6-dimethoxy-1,3,5-triazine in step S1 is 1mol:(4.1-4.5)mol.

6. The process for preparing an anti-static polylactic acid ultrafine fiber fabric according to claim 1, wherein the anti-static agent is added to the polylactic acid solution in an amount of 0.1 to 5% by weight. The reaction temperature in step S1 is 20-35 DEG C, and the reaction time is 2-5h.

7. The process for preparing the anti-static polylactic acid ultrafine fiber fabric according to claim 1, wherein the anti-static agent is added to the polylactic acid solution in an amount of 0.1 to 5% by weight. The ratio of the tetrakis (triazine dimethoxy) phosphorus intermediate and boron tribromide in step S2 is 1mol:(6.5-8)mol.

8. The process for preparing the anti-static polylactic acid ultrafine fiber fabric according to claim 1, wherein the anti-static agent is added to the polylactic acid solution in an amount of 0.1 to 5% by weight. In step S3, the lactide is any one of D-lactide, L-lactide, or D,L-lactide.

9. The process for preparing the anti-static polylactic acid ultrafine fiber fabric according to claim 1, wherein the anti-static agent is added to the polylactic acid solution in an amount of 0.1 to 5% by weight. The proportion of the lactide, the hexahydroxyphosphorus nitrogen intermediate and the stannous octoate in the step S3 is 1 mol:(0.15-0.25) mol:(0.02-0.05) mol.

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