Fully-dull fine denier polyamide 56 pre-oriented yarn and melt direct spinning method thereof

Abstract

The application provides a full-dull fine-denier bio-based polyamide 56 pre-oriented yarn and a melt direct spinning method thereof. The full-dull fine-denier polyamide 56 pre-oriented yarn produced by the application is stable, has few floating filaments and injection head filaments, has high fiber production rate, and has excellent mechanical properties and dyeing performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyamide materials, and particularly relates to full-dull polyamide 56 melt direct spinning fine denier pre-oriented yarn and a preparation method thereof. BACKGROUND

[0002] Melt spinning is one of main forming methods of synthetic fibers, which is also called melt spinning. Melt spinning is divided into direct spinning method and chip spinning method. Direct spinning is to directly send polymer melt after polymerization to spinning; chip spinning needs to send polymer solution to spinning after casting, granulating and drying and other pre-spinning preparation processes.

[0003] The monomer content in the polymer of polyamide 6 is relatively high (about 10 wt%), and the chip needs to be extracted before melt spinning can be realized. At present, melt direct spinning cannot be realized in industrialization. In the spinning process of polyamide 66, gel is easily produced, dyeing is difficult, and other problems are encountered, and great difficulties are faced in the melt direct spinning technology of civil silk. Although melt direct spinning is partially realized in the field of industrial silk, the melt conveying pipeline and the spinning box need to be regularly disassembled, calcined and cleaned, which increases the spinning cost.

[0004] Patent No. CN105669969 B discloses a nylon 6 polymerization method and a melt direct spinning method. The nylon 6 prepolymer is prepared at a low temperature, the oligomer content in the melt is pre-controlled, then the polymerization is completed before the generation of a large amount of cyclic oligomers through the method of kinetic strengthening of polycondensation reaction, and the nylon 6 polymer melt with a certain molecular weight is obtained. The extractable content in the obtained product is ≤1.5 wt%, and the cyclic dimer content is ≤0.2 wt%. Then, the melt spinning is directly formed after the end of the kinetic strengthening of polycondensation reaction, but there is still no technical breakthrough and industrialization case.

[0005] Patent No. CN103668510 A discloses a device and a method for producing fine denier or ultra-fine denier nylon 66 filament. The device includes an evaporator, a preheater, a reactor, a flash evaporator and a post-polycondensation system. After the polycondensation reaction of the nylon 66 salt aqueous solution, the nylon 66 melt is obtained, and then the nylon 66 melt is directly spun to prepare fine denier or ultra-fine denier nylon 66 POY filament. The spinning speed is 4200-4300 m / min, the spinning speed is low, the yield is low, and the fiber strength is low.

[0006] The bio-based polyamide 56 uses bio-based pentanediamine as a monomer raw material. The carbon emission of the bio-based polyamide 56 per unit weight is reduced by more than 50% compared with the carbon emission of nylon 66 and nylon 6 of the same weight. The popularization and application of the bio-based polyamide 56 will have a positive effect on improving the dependence on imported key materials in China and is of great significance to the sustainable development of solving the dependence on fossil resources and low-carbon emission reduction. The bio-based polyamide 56 material has excellent mechanical properties, moisture absorption and quick drying, skin friendliness, wear resistance, good softness, and low-temperature easy dyeing characteristics, and has a wide application prospect in the fields of civil filaments, staple fibers, industrial filaments, continuous bulk continuous filaments, monofilaments and the like. However, there is no related research and report on the preparation of fine denier pre-oriented yarn by melt direct spinning one-step method of full-dull polyamide 56. SUMMARY

[0007] In order to realize the industrial production requirements of the bio-based polyamide 56 melt direct spinning, the bio-based polyamide 56 pre-oriented yarn with large capacity and high performance is prepared by optimizing the melt direct spinning process, the production is stable, the number of floating monofilaments and injection head filaments is small, the fiber production rate is high, and the mechanical properties and dyeing properties are excellent.

[0008] A first object of the present application is to provide a full-dull fine denier polyamide 56 pre-oriented yarn, which is prepared by melt direct spinning one-step method, the full-dull fine denier polyamide 56 pre-oriented yarn has a fineness of ≤95 dtex, or ≤78 dtex, or ≤60 dtex, or ≤50 dtex, for example, 14-95 dtex.

[0009] In some specific embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a yarn evenness of ≤1.0%, preferably ≤0.9%, further preferably ≤0.85%, and more preferably ≤0.8%.

[0010] In some specific embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a breaking strength of 3.1-4.3 cN / dtex; a breaking strength coefficient of variation (CV) of ≤4%, preferably ≤3.5%, further preferably ≤3.0%, and more preferably ≤2.5%.

[0011] In some specific embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has an elongation at break of 60-95%; an elongation at break coefficient of variation (CV) of ≤4.5%, preferably ≤4.0%, further preferably ≤3.5%, and more preferably ≤3.0%.

[0012] In some embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a breaking strength of 3.2-4.2 cN / dtex, or 3.3-4.1 cN / dtex, or 3.4-4.0 cN / dtex; and / or, an elongation at break of 68-86%, or 70-83%, or 72-80%.

[0013] In some embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a dyeing uniformity (grey card) of ≥ 3.5 grade, preferably ≥ 4.0 grade, further preferably ≥ 4.5 grade, and more preferably ≥ 4.7 grade.

[0014] In some embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a dyeing double A rate of ≥ 95%, preferably ≥ 96%, further preferably ≥ 97%, and more preferably ≥ 98%; and / or, a cake appearance double A rate of ≥ 96%, preferably ≥ 97%, further preferably ≥ 97.5%, and more preferably ≥ 98%.

[0015] A second object of the present application is to provide a melt direct spinning method of the full-dull fine denier polyamide 56 pre-oriented yarn, which comprises at least the following steps: polyamide 56 melt is fed to a spinning box through a melt booster pump, a melt filter, and a melt delivery pipe to form a nascent yarn, which is cooled, oiled, and wound to obtain the full-dull fine denier polyamide 56 pre-oriented yarn.

[0016] The content of titanium dioxide in the polyamide 56 melt is 1.2-1.8 wt%, preferably 1.3-1.7 wt%, further preferably 1.4-1.65 wt%, and more preferably 1.45-1.63 wt%.

[0017] In some embodiments, the titanium dioxide is added in the flash process.

[0018] In some embodiments, the polyamide 56 melt has a relative viscosity of 2.38-2.9, preferably 2.4-2.88, more preferably 2.42-2.86, and more preferably 2.45-2.84.

[0019] In some embodiments, the polyamide 56 melt has an end amino group content of 35-90 mmol / kg, preferably 38-80 mmol / kg, more preferably 40-70 mmol / kg, and further preferably 42-60 mmol / kg.

[0020] In some specific embodiments, the polyamide 56 melt has an equilibrium moisture content of 300-900 ppm, preferably 350-850 ppm, more preferably 400-800 ppm, and further preferably 450-750 ppm.

[0021] In some specific embodiments, the method for preparing the polyamide 56 melt comprises the following steps: preparing a polyamide 56 salt solution from pentanediamine, adipic acid and water, and then pre-polymerizing, flashing and polycondensing to obtain the polyamide 56 melt.

[0022] In some specific embodiments, the molar ratio of the pentanediamine to adipic acid is (1-1.09):1.

[0023] In some specific embodiments, the polyamide 56 salt solution has a concentration of 40-80 wt%.

[0024] In some specific embodiments, the polyamide 56 salt solution has a pH value of 6.5-8.8, preferably 6.7-8.7, further preferably 6.8-8.6, and more further preferably 6.9-8.5.

[0025] In some specific embodiments, the pre-polymerization is performed at a pressure of 1.4-2.4 MPa, preferably 1.5-2.3 MPa, further preferably 1.6-2.2 MPa, and more further preferably 1.7-2.1 MPa, and at a temperature of 180-260℃, preferably 200-258℃, further preferably 210-256℃, and more further preferably 220-254℃.

[0026] In some specific embodiments, the polycondensation is performed at a pressure of -(0-0.09) MPa, preferably -(0.01-0.08) MPa, further preferably -(0.02-0.07) MPa, and more further preferably -(0.03-0.06) MPa, and at a temperature of 266-288℃, preferably 267-287℃, further preferably 268-286℃, and more further preferably 269-285℃.

[0027] In some specific embodiments, the melt filter is provided with a filter screen having a specification of 3-15 μm, preferably 5-13 μm, and more further preferably 8-10 μm. The filter screen is made of metal or non-woven fabric, and is preferably made of stainless steel.

[0028] In some specific embodiments, the spinning assembly of the spinning beam is provided with a filter screen having a specification of 8-18 μm, preferably 10-15 μm. The filter screen is made of metal or non-woven fabric, and is preferably made of non-woven fabric.

[0029] The preparation method of the present application obtains the effect of extinction by adding titanium dioxide, the method is simple and easy to operate, the production cost is low, and the inventor finds that by setting a filter screen in the melt filter and the spinning assembly, the combination of two filtrations effectively reduces the larger particle size titanium dioxide agglomerate particles, makes the titanium dioxide more uniformly distributed in the melt, improves the overall uniformity of the polyamide 56 melt, not only obtains a better extinction effect, but also reduces the broken filaments during spinning, prolongs the assembly replacement cycle, and is suitable for industrial production.

[0030] In some specific embodiments, the dispersed particle size of the titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, preferably, the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is more than 98%; more preferably, the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is more than 95%.

[0031] In some specific embodiments, the temperature of the melt delivery pipeline is controlled to be 265-290°C, preferably 268-288°C, further preferably 270-286°C, and more further preferably 272-284°C.

[0032] In some specific embodiments, the dynamic viscosity of the polyamide 56 melt is controlled to be ≥200 pa*s, preferably ≥210 pa*s, further preferably ≥220 pa*s, for example 230-350 pa*s, from the melt booster pump to the spinning beam.

[0033] In some specific embodiments, the temperature of the spinning beam is 270-292°C, more preferably 273-290°C, further preferably 275-288°C, and more further preferably 277-285°C.

[0034] In some specific embodiments, the spinning assembly pressure of the spinning beam is 10-25 MPa, preferably 12-22 MPa, and further preferably 14-18 MPa.

[0035] In some specific embodiments, the melt pressure at the inlet of the spinning beam is ≥9.0 MPa, preferably ≥10.0 MPa, and further preferably ≥11.0 MPa, for example 12.0-16.0 MPa.

[0036] In some specific embodiments, the polyamide 56 melt is delivered to the spinning beam through a melt pipeline, accurately metered by a metering pump, and injected into the spinning assembly to form a primary filament from the spinneret.

[0037] In some preferred specific embodiments, a saturated superheated steam device and a monomer suction device are arranged below the spinning beam. The inventors make the saturated superheated steam sprayed from all around below the spinneret, the polyamide oligomer solution overflowing from the spinneret and the fiber surface is dissolved in the saturated superheated steam, and then taken away by the monomer suction device, keeping the spinneret and below clean, prolonging the shovel plate cycle of the spinning assembly, reducing the phenomena of jet yarn and broken filaments caused by oligomers in the spinning process, effectively improving the spinning production stability and yield.

[0038] In some specific embodiments, the temperature of the saturated superheated steam device is controlled to be 100-250℃, further 110-240℃, and more further 120-230℃.

[0039] In some specific embodiments, the pressure of the saturated superheated steam device is controlled to be 0.8-2.8bar, further 1.0-2.5bar, and more further 1.2-2.3bar.

[0040] In some specific embodiments, the pressure of the monomer suction device is controlled to be ≥0.6MPa, further ≥0.65MPa, and more further 0.7-1.0MPa.

[0041] In some specific embodiments, the oil used for the oiling can be a commonly used polyamide pre-oriented yarn oiling agent on the market, such as DAKO oiling agent, Zhuben oiling agent, Keke oiling agent, Sima oiling agent, etc.

[0042] In some specific embodiments, the winding speed is ≥4200m / min, preferably ≥4300m / min, more preferably ≥4400m / min, and further preferably 4500-5500m / min.

[0043] In some specific embodiments, the winding is carried out between two godets, and the nascent yarn passes through the CR1 godet and the CR2 godet in turn, and is then wound into shape; and / or,

[0044] The CR1 godet speed is 4200-5500m / min, preferably 4300-5300m / min, more preferably 4400-5000m / min, and further preferably 4500-4900m / min; and / or,

[0045] The CR2 godet speed is 4220-5550m / min, preferably 4320-5350m / min, more preferably 4420-5050m / min, and further preferably 4520-4950m / min.

[0046] In some specific embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a broken filament frequency of ≤ 2 filaments per 1 spinning position per 24 hours, preferably ≤ 1 filament per 1 spinning position per 24 hours, and more preferably ≤ 0 filaments per 1 spinning position per 24 hours.

[0047] In some specific embodiments, the full-dull fine denier polyamide 56 pre-oriented yarn has a production rate of ≥ 96%, preferably ≥ 96.5%, further preferably ≥ 97%, and more preferably ≥ 97.5%.

[0048] The full-dull fine denier polyamide 56 pre-oriented yarn provided by the present application can be applied in the fields of underwear, shirts, suits, yoga clothes, down jackets, outdoor jackets, socks, luggage, curtains, shoe materials, embroidery threads, trademarks, sand publishing, work clothes, sportswear, elastic bands, and the like.

[0049] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, thereby obtaining preferred examples of the present application. The reagents and raw materials used in the present application are commercially available.

[0050] The positive progress effect of the present application is that:

[0051] First, the production raw material 1,5-pentanediamine of the polyamide 56 pre-oriented yarn provided by the present application is made by a biological method, which is a green material, does not depend on petroleum resources and does not cause serious pollution to the environment, and can reduce the emission of carbon dioxide and the generation of greenhouse effect, thereby adapting to the development trend of carbon neutralization.

[0052] Second, by using the melt direct spinning method of the full-dull fine denier polyamide 56 pre-oriented yarn, the parameters such as the melt delivery temperature, the dynamic viscosity of the melt, the spinning box temperature, the component pressure, and the melt pressure at the inlet are controlled, which not only can realize the stable production of full-dull fine denier polyamide 56 pre-oriented yarns of various specifications, but also can effectively reduce the gel content in the melt from the melt booster pump to the spinning box.

[0053] Specifically, the annual output of the full-dull fine denier polyamide 56 pre-oriented yarn can reach 0.8-2.0 million tons per line; the spinning position can be 192 positions per line, 144 positions per line, 120 positions per line, or 96 positions per line or less; and the number of spinning heads can be 8-24 heads per position, preferably 12-24 heads per position. This method saves the steps of melt pelletizing, chip drying, and screw melting in the chip spinning process, greatly reducing the production cost of the polyamide 56 pre-oriented yarn. The gel content can be controlled to be ≤ 1.1 wt% per 6 months, preferably ≤ 1.0 wt% per 6 months, more preferably ≤ 0.9 wt% per 6 months, and further preferably ≤ 0.8 wt% per 6 months. The reduction of the gel content greatly reduces the number of times of disassembly, calcination, and cleaning of the melt pipeline and the spinning box, thereby reducing the production cost.

[0054] Third, the full-dull fine denier polyamide 56 pre-oriented yarn of the present application is stable in production, has less floating single yarn and injection head yarn, high fiber production rate, excellent mechanical properties and dyeing performance. DETAILED DESCRIPTION

[0055] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. The experimental methods not specified in the following embodiments are selected according to conventional methods and conditions or according to the instructions of the goods.

[0056] Test method:

[0057] (1) Relative viscosity: by Ubbelohde viscometer concentrated sulfuric acid method: 0.25±0.0002g of polyamide melt sample was accurately weighed online after drying, and was dissolved in 50mL of concentrated sulfuric acid (96wt%); the concentrated sulfuric acid flow time t0 and the polyamide sample solution flow time t were measured and recorded in a 25℃ constant temperature water bath. The viscosity number calculation formula: relative viscosity = t / t0; t - solution flow time; t0 - solvent flow time.

[0058] (2) Amino terminal: determined according to automatic titrator.

[0059] (3) Moisture content: determined according to Karl Fischer moisture titrator.

[0060] (4) Fineness: determined according to GB / T 14343.

[0061] (5) Unevenness of yarn: the unevenness of yarn refers to the degree of thickness change of the yarn along the length direction of itself, including unevenness of yarn appearance diameter and unevenness of linear density, and the detection equipment is Uster evenness tester.

[0062] (6) Breaking strength, breaking strength variation coefficient (CV) %, breaking elongation, breaking elongation variation coefficient (CV) %: according to GB / T 14344-2008 chemical fiber fiber tensile property test method; 0.05±0.005cN / dtex pre-tension was applied, the holding distance was 250mm, and the tensile speed was 1000mm / min.

[0063] (7) Dyeing uniformity (grey card) / grade: according to FZ / T 50008 polyamide filament dyeing uniformity test method.

[0064] (8) Dyeing double A rate: Dyeing double A rate = ((weight of fibers with dyeing evenness ≥ 4.5 grade) / total weight of all dyed fibers) x 100%.

[0065] (9) Yarn cake appearance double A rate: Artificially judged.

[0066] (10) Broken filament frequency: Artificially counted.

[0067] (11) Production rate: Production rate = (mass of prepared finished fibers / total mass of polyamide melt input) x 100%.

[0068] (12) Gel content: Randomly select 6 melt samples from melt conveying pipelines after 6 months of line operation, measure and take average value according to the following method, take the mass of the melt sample after cooling and drying as A1, use Soxhlet extraction method for reflux extraction, take out the sample for drying and weighing, take the mass of the sample in the filter paper bag as A2, the calculation formula of the gel content is: gel content wt% = A2 / A1*100%.

[0069] Example 1: Fully-dull fine denier polyamide 56 pre-oriented yarn 14 dtex / 7f

[0070] (1) Prepare a polyamide 56 salt solution from pentanediamine, adipic acid and water, then obtain a polyamide 56 melt through pre-polymerization, flashing and polycondensation;

[0071] The molar ratio of the pentanediamine and adipic acid is 1.05:1; the concentration of the polyamide 56 salt solution is 55 wt%, and the pH value is 7.8;

[0072] The pressure of the pre-polymerization is 1.75 MPa, and the temperature is 240°C; the pressure of the polycondensation is -0.03 MPa, and the temperature is 275°C;

[0073] The relative viscosity of the polyamide 56 melt is 2.5, the end amino group content is 45 mmol / kg, and the equilibrium moisture content is 400 ppm;

[0074] The titanium dioxide content of the polyamide 56 melt is 1.50 wt%, which is added during the flashing process.

[0075] (2) The polyamide 56 melt obtained in step (1) is conveyed to a spinning beam through a melt booster pump, a melt filter and a melt conveying pipeline to form a nascent yarn, which is cooled, oiled and wound to obtain a fully-dull fine denier polyamide 56 pre-oriented yarn.

[0076] A 10 μm stainless steel filter screen is arranged in the melt filter; a 15 μm non-woven fabric filter screen is arranged in the spinning assembly of the spinning beam.

[0077] The dispersed particle size of the titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the proportion of the particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 98.2%; the proportion of the particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 95.4%;

[0078] The temperature of the melt delivery pipeline is controlled to be 275℃; the dynamic viscosity of the polyamide 56 melt is controlled to be 220 pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 276℃; the pressure of the spinning beam spinning assembly is 14 MPa; the melt pressure at the spinning beam inlet is 11.0 MPa.

[0079] The saturated superheated steam device and the monomer suction device are arranged below the spinning beam, wherein the temperature of the saturated superheated steam device is controlled to be 140℃, the pressure of the saturated superheated steam device is controlled to be 1.5 bar, and the pressure of the monomer suction device is controlled to be 0.6 MPa.

[0080] The winding speed is 4500 m / min; the winding is carried out between two godets, the nascent filaments pass through the CR1 godet and the CR2 godet in turn, and are then wound into a shape, the CR1 godet speed is 4500 m / min; the CR2 godet speed is 4520 m / min.

[0081] The annual output of the full-dull fine denier polyamide 56 pre-oriented yarn according to the embodiment can reach 40000 tons per line, the spinning position is 96 per line, and the number of spinning heads is 12 per position.

[0082] Example 2 full-dull fine denier polyamide 56 pre-oriented yarn 25 dtex / 13 f

[0083] (1) pentanediamine, adipic acid and water are used to prepare a polyamide 56 salt solution, and then pre-polymerization, flashing and polycondensation are carried out to obtain a polyamide 56 melt;

[0084] The molar ratio of the pentanediamine and the adipic acid is 1.06:1; the concentration of the polyamide 56 salt solution is 53 wt%, and the pH value is 7.9;

[0085] The pre-polymerization pressure is 1.73 MPa, and the pre-polymerization temperature is 245℃; the polycondensation pressure is -0.04 MPa, and the polycondensation temperature is 278℃;

[0086] The relative viscosity of the polyamide 56 melt is 2.53, the end amino group content is 48 mmol / kg, and the equilibrium moisture content is 500 ppm;

[0087] The titanium dioxide content of the polyamide 56 melt is 1.53 wt%, which is added in the flashing process.

[0088] (2) the polyamide 56 melt obtained in step (1) is subjected to a melt booster pump, a melt filter, a melt delivery pipe, and a spinning beam to form a nascent yarn, and the nascent yarn is subjected to cooling, oiling, and winding to obtain a full-dull fine denier polyamide 56 pre-oriented yarn;

[0089] The melt filter is provided with a 10 μm stainless steel filter screen, and the spinning assembly of the spinning beam is provided with a 15 μm non-woven fabric filter screen.

[0090] The dispersion particle size of titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, and the particle distribution ratio of titanium dioxide with a dispersion particle size of 0.2-0.4 μm is 98.6%; the particle distribution ratio of titanium dioxide with a dispersion particle size of 0.2-0.3 μm is 95.7%.

[0091] The temperature of the melt delivery pipe is controlled to be 278°C; the dynamic viscosity of the polyamide 56 melt is controlled to be 230 pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 278°C; the pressure of the spinning assembly of the spinning beam is 15 MPa; and the melt pressure at the inlet of the spinning beam is 12.0 MPa.

[0092] The spinning beam is provided below with a saturated superheated steam device and a monomer suction device, wherein the temperature of the saturated superheated steam device is controlled to be 150°C, the pressure of the saturated superheated steam device is controlled to be 1.3 bar, and the pressure of the monomer suction device is controlled to be 0.7 MPa.

[0093] The winding speed is 4600 m / min; the winding is carried out between two godets, and the nascent yarn passes through a CR1 godet and a CR2 godet in sequence and is then wound into shape, wherein the speed of the CR1 godet is 4600 m / min, and the speed of the CR2 godet is 4630 m / min.

[0094] The annual output of the full-dull fine denier polyamide 56 pre-oriented yarn described in the embodiment can reach 65,000 tons per line, the spinning position is 96 positions per line, and the number of spinning heads is 12 heads per position.

[0095] Example 3 full-dull fine denier polyamide 56 pre-oriented yarn 26 dtex / 24 f

[0096] (1) pentanediamine, adipic acid, and water are used to prepare a polyamide 56 salt solution, and then the polyamide 56 salt solution is subjected to pre-polymerization, flashing, and polycondensation to obtain a polyamide 56 melt;

[0097] The molar ratio of the pentanediamine and the adipic acid is 1.08:1; the concentration of the polyamide 56 salt solution is 57 wt%, and the pH value is 8.1.

[0098] The pressure of the prepolymerization is 1.76 MPa, and the temperature is 248℃; the pressure of the polycondensation is -0.05 MPa, and the temperature is 280℃;

[0099] The relative viscosity of the polyamide 56 melt is 2.64, the end amino group content is 52 mmol / kg, and the equilibrium moisture content is 500 ppm;

[0100] The titanium dioxide content of the polyamide 56 melt is 1.55 wt%, and is added in the flash process.

[0101] (2) The polyamide 56 melt obtained in step (1) is sent to a spinning beam through a melt booster pump, a melt filter, and a melt conveying pipe to form a nascent yarn, and the nascent yarn is cooled, oiled, and wound to obtain a full-dull fine denier polyamide 56 pre-oriented yarn.

[0102] A 5 μm stainless steel filter screen is arranged in the melt filter; and a 15 μm non-woven fabric filter screen is arranged in the spinning assembly of the spinning beam.

[0103] The dispersed particle size of titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 98.8%, and the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 96.4%.

[0104] The temperature of the melt conveying pipe is controlled to be 280℃; the dynamic viscosity of the polyamide 56 melt is controlled to be 240 pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 280℃; the pressure of the spinning assembly of the spinning beam is 13 MPa; and the melt pressure at the inlet of the spinning beam is 12.0 MPa.

[0105] A saturated superheated steam device and a monomer suction device are arranged below the spinning beam, wherein the temperature of the saturated superheated steam device is controlled to be 120℃, the pressure of the saturated superheated steam device is controlled to be 1.6 bar, and the pressure of the monomer suction device is controlled to be 0.75 MPa.

[0106] The winding speed is 4700 m / min; the winding is performed between two godets, and the nascent yarn passes through a CR1 godet and a CR2 godet in sequence and is then wound to form a shape, wherein the speed of the CR1 godet is 4700 m / min, and the speed of the CR2 godet is 4750 m / min.

[0107] The annual output of the full-dull fine denier polyamide 56 pre-oriented yarn described in the embodiment can reach 70,000 tons per line, the spinning position is 96 per line, and the number of spinning heads is 12 per position.

[0108] Example 4: Full-dull fine denier polyamide 56 pre-oriented yarn 30 dtex / 24 f

[0109] (1) pentanediamine, adipic acid and water are prepared into a polyamide 56 salt solution, and then pre-polymerization, flash evaporation and polycondensation are performed to obtain a polyamide 56 melt;

[0110] The molar ratio of the pentanediamine and the adipic acid is 1.05:1; the concentration of the polyamide 56 salt solution is 54 wt%, and the pH value is 8.2;

[0111] The pressure of the pre-polymerization is 1.78 MPa, and the temperature is 252℃; the pressure of the polycondensation is -0.06 MPa, and the temperature is 284℃;

[0112] The relative viscosity of the polyamide 56 melt is 2.78, the end amino group content is 50 mmol / kg, and the equilibrium water content is 450 ppm;

[0113] The titanium dioxide content of the polyamide 56 melt is 1.6 wt%, which is added in the flash evaporation process.

[0114] (2) The polyamide 56 melt obtained in step (1) is sent to a spinning beam through a melt booster pump, a melt filter and a melt conveying pipeline to form a primary filament, and the primary filament is cooled, oiled and wound to obtain a full-dull fine denier polyamide 56 pre-oriented yarn;

[0115] A 10 μm stainless steel filter screen is arranged in the melt filter; and a 15 μm non-woven fabric filter screen is arranged in the spinning assembly of the spinning beam;

[0116] The dispersion particle size of the titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the particle distribution ratio of the titanium dioxide with a dispersion particle size of 0.2-0.4 μm is 98.5%, and the particle distribution ratio of the titanium dioxide with a dispersion particle size of 0.2-0.3 μm is 96.2%;

[0117] The temperature of the melt conveying pipeline is controlled to be 282℃; the dynamic viscosity of the polyamide 56 melt is controlled to be 250 pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 282℃; the pressure of the spinning assembly of the spinning beam is 14 MPa; and the melt pressure at the inlet of the spinning beam is 11.0 MPa.

[0118] A saturated superheated steam device and a monomer suction device are arranged below the spinning beam, wherein the temperature of the saturated superheated steam device is controlled to be 120℃, the pressure of the saturated superheated steam device is controlled to be 1.6 bar, and the pressure of the monomer suction device is controlled to be 0.7 MPa.

[0119] The winding speed is 4400 m / min; the winding is carried out between two godets, the nascent yarn passes through CR1 godet and CR2 godet in turn, and is wound into shape, the CR1 godet speed is 4400 m / min; the CR2 godet speed is 4430 m / min.

[0120] The annual output of the fully-dull fine denier polyamide 56 pre-oriented yarn is up to 80,000 tons per line, the spinning position is 96 per line, and the number of spinning heads is 12 per position.

[0121] Example 5 fully-dull fine denier polyamide 56 pre-oriented yarn 40 dtex / 48 f

[0122] (1) preparing a polyamide 56 salt solution from pentanediamine, adipic acid and water, then obtaining a polyamide 56 melt through pre-polymerization, flashing and polycondensation;

[0123] The molar ratio of the pentanediamine and adipic acid is 1.08:1; the concentration of the polyamide 56 salt solution is 55 wt%, and the pH value is 8.3;

[0124] The pre-polymerization pressure is 1.72 Mpa, and the temperature is 255℃; the polycondensation pressure is -0.07 Mpa, and the temperature is 285℃;

[0125] The relative viscosity of the polyamide 56 melt is 2.82, the end amino group content is 45 mmol / kg, and the equilibrium moisture content is 400 ppm;

[0126] The titanium dioxide content of the polyamide 56 melt is 1.6 wt%, which is added in the flashing process.

[0127] (2) the polyamide 56 melt obtained in step (1) is sent to a spinning beam through a melt booster pump, a melt filter and a melt conveying pipeline to form a nascent yarn, the nascent yarn is cooled, oiled and wound to obtain a fully-dull fine denier polyamide 56 pre-oriented yarn;

[0128] A 10 μm stainless steel filter screen is arranged in the melt filter; a 15 μm non-woven fabric filter screen is arranged in the spinning assembly of the spinning beam;

[0129] The dispersion particle size of titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the particle distribution ratio of titanium dioxide with a dispersion particle size of 0.2-0.4 μm is 98.0%, and the particle distribution ratio of titanium dioxide with a dispersion particle size of 0.2-0.3 μm is 96.5%;

[0130] The temperature of the melt delivery pipe is controlled at 282℃; the dynamic viscosity of the polyamide 56 melt is controlled at 255pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 284℃; the pressure of the spinning beam is 16MPa; the melt pressure at the inlet of the spinning beam is 12.0MPa.

[0131] A saturated superheated steam device and a monomer suction device are arranged below the spinning beam, wherein the temperature of the saturated superheated steam device is controlled at 130℃, the pressure of the saturated superheated steam device is controlled at 1.3bar, and the pressure of the monomer suction device is controlled at 0.65MPa.

[0132] The winding speed is 4500m / min; the winding is carried out between two godets, and the nascent filaments pass through the CR1 godet and the CR2 godet in turn, and are then wound into a shape, wherein the speed of the CR1 godet is 4520m / min, and the speed of the CR2 godet is 4500m / min.

[0133] The annual output of the fully-dull fine denier polyamide 56 pre-oriented yarn according to the embodiment is up to 10,000 tons per line, the spinning position is 96 positions per line, and the number of spinning heads is 12 per position.

[0134] Example 6: Fully-dull fine denier polyamide 56 pre-oriented yarn 55dtex / 51f

[0135] (1) Preparing a polyamide 56 salt solution from pentanediamine, adipic acid and water, and then obtaining a polyamide 56 melt through prepolymerization, flashing and polycondensation;

[0136] The molar ratio of the pentanediamine and the adipic acid is 1.04:1; the concentration of the polyamide 56 salt solution is 52wt%, and the pH value is 8.0;

[0137] The pressure of the prepolymerization is 1.76Mpa, and the temperature is 253℃; the pressure of the polycondensation is -0.05Mpa, and the temperature is 282℃;

[0138] The relative viscosity of the polyamide 56 melt is 2.75, the end amino group content is 50mmol / kg, and the equilibrium moisture content is 500ppm;

[0139] The titanium dioxide content of the polyamide 56 melt is 1.53wt%, which is added in the flashing process.

[0140] (2) The polyamide 56 melt obtained in step (1) is sent to the spinning beam through a melt booster pump, a melt filter and a melt delivery pipe to form nascent filaments, and the nascent filaments are cooled, oiled and wound to obtain the fully-dull fine denier polyamide 56 pre-oriented yarn.

[0141] The melt filter is provided with a 10 μm stainless steel filter screen; the spinning pack of the spinning beam is provided with an 18 μm non-woven fabric filter screen;

[0142] The dispersed particle size of the titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 98.4%, and the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 97.8%;

[0143] The temperature of the melt delivery pipeline is controlled to be 280°C; the dynamic viscosity of the polyamide 56 melt is controlled to be 250 pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 280°C; the pressure of the spinning pack of the spinning beam is 14 MPa; the melt pressure at the inlet of the spinning beam is 13.0 MPa.

[0144] The spinning beam is provided below with a saturated superheated steam device and a monomer suction device, wherein the temperature of the saturated superheated steam device is controlled to be 150°C, the pressure of the saturated superheated steam device is controlled to be 1.5 bar, and the pressure of the monomer suction device is controlled to be 0.7 MPa.

[0145] The winding speed is 4700 m / min; the winding is carried out between two godets, the nascent filaments pass through a CR1 godet and a CR2 godet in turn, and are then wound into shape, the speed of the CR1 godet is 4700 m / min, and the speed of the CR2 godet is 4720 m / min.

[0146] The annual output of the full-dull fine denier polyamide 56 pre-oriented yarn according to the embodiment can reach 12,000 tons per line, the spinning position is 96 positions per line, and the number of spinning heads is 12 per position.

[0147] Example 7 Full-dull fine denier polyamide 56 pre-oriented yarn 95 dtex / 68 f

[0148] (1) pentanediamine, adipic acid and water are used to prepare a polyamide 56 salt solution, and then pre-polymerization, flashing and polycondensation are carried out to obtain a polyamide 56 melt;

[0149] The molar ratio of the pentanediamine and the adipic acid is 1.03:1; the concentration of the polyamide 56 salt solution is 54 wt%, and the pH value is 8.1;

[0150] The pressure of the pre-polymerization is 1.73 MPa, and the temperature is 252°C; the pressure of the polycondensation is -0.04 MPa, and the temperature is 282°C;

[0151] The relative viscosity of the polyamide 56 melt is 2.73, the end amino group content is 52 mmol / kg, and the equilibrium moisture content is 600 ppm;

[0152] The titanium dioxide content of the polyamide 56 melt is 1.52 wt%, which is added in the flash process.

[0153] (2) The polyamide 56 melt obtained in step (1) is subjected to a melt booster pump, a melt filter, a melt delivery pipe to a spinning beam, to form a nascent yarn, which is cooled, oiled and wound to obtain a full-dull fine denier polyamide 56 pre-oriented yarn.

[0154] A 10 μm stainless steel filter screen is arranged in the melt filter; a 15 μm non-woven fabric filter screen is arranged in the spinning assembly of the spinning beam.

[0155] The dispersed particle size of titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, and the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 98.6%; the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 97.6%.

[0156] The temperature of the melt delivery pipe is controlled to be 282°C; the dynamic viscosity of the polyamide 56 melt is controlled to be 240 pa*s from the melt booster pump to the spinning beam; the temperature of the spinning beam is 280°C; the pressure of the spinning assembly of the spinning beam is 15 MPa; the melt pressure at the inlet of the spinning beam is 11.0 MPa.

[0157] A saturated superheated steam device and a monomer suction device are arranged below the spinning beam, wherein the temperature of the saturated superheated steam device is controlled to be 130°C, the pressure of the saturated superheated steam device is controlled to be 1.6 bar, and the pressure of the monomer suction device is controlled to be 0.7 MPa.

[0158] The winding speed is 4800 m / min; the winding is carried out between two godets, and the nascent yarn passes through a CR1 godet and a CR2 godet in sequence, and is then wound to form a shape, wherein the speed of the CR1 godet is 4780 m / min; the speed of the CR2 godet is 4810 m / min.

[0159] The annual output of the full-dull fine denier polyamide 56 pre-oriented yarn described in the embodiment can reach 15,000 tons per line, the spinning position is 96 positions per line, and the number of spinning heads is 12 per position.

[0160] Comparative Example 1 full-dull fine denier polyamide 56 pre-oriented yarn 26 dtex / 24 f

[0161] The preparation method is the same as that in Example 3, except that the polyamide 56 melt obtained in step (1) is first granulated and dried to obtain a chip, and the chip is spun to prepare a full-dull fine denier polyamide 56 pre-oriented yarn.

[0162] Comparative Example 2 fully-dull fine denier polyamide 56 pre-oriented yarn 40 dtex / 48 f

[0163] The preparation method is the same as in Example 5, except that a 20 μm stainless steel filter screen is provided in the melt filter; the spinning pack of the spinning beam is provided with a 20 μm non-woven fabric filter screen; the dispersed particle size of the titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 93.0%; the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 92.3%.

[0164] Comparative Example 3 fully-dull fine denier polyamide 56 pre-oriented yarn 40 dtex / 48 f

[0165] The preparation method is the same as in Example 5, except that a 20 μm stainless steel filter screen is provided in the melt filter; the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 93.6%; the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 93.2%.

[0166] Comparative Example 4 fully-dull fine denier polyamide 56 pre-oriented yarn 40 dtex / 48 f

[0167] The preparation method is the same as in Example 5, except that a 20 μm non-woven fabric filter screen is provided in the spinning pack of the spinning beam; the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.4 μm is 92.8%; the proportion of particles with a titanium dioxide dispersed particle size of 0.2-0.3 μm is 92.4%.

[0168] Comparative Example 5 fully-dull fine denier polyamide 56 pre-oriented yarn 40 dtex / 48 f

[0169] The preparation method is the same as in Example 5, except that the dynamic viscosity of the polyamide 56 melt is controlled to 170 pa*s.

[0170] Comparative Example 6 fully-dull fine denier polyamide 56 pre-oriented yarn 40 dtex / 48 f

[0171] The preparation method is the same as in Example 5, except that the melt pressure at the inlet of the spinning beam is 6.0 MPa.

[0172] Table 1 Parameters of polyamide 56 pre-oriented yarns produced in the Examples and Comparative Examples

[0173]

[0174] As shown in Table 1, the melt direct spinning method for fully dull fine denier polyamide 56 pre-oriented yarn described in this invention, by controlling parameters such as melt conveying temperature, melt dynamic viscosity, spinning box temperature, component pressure, and melt pressure at the inlet, not only enables stable production of various specifications of fully dull fine denier polyamide 56 pre-oriented yarn and obtains high-performance pre-oriented yarn, but also effectively reduces the gel content in the melt booster pump to the spinning box. Furthermore, the two-stage filtration combination effectively reduces larger-diameter titanium dioxide agglomerates, resulting in a more uniform distribution of titanium dioxide in the melt, improving the overall uniformity of the polyamide 56 melt, extending the spinning component replacement cycle, and making it suitable for industrial production.

[0175] The above description of the embodiments is provided to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A fully dull fine denier polyamide 56 pre-oriented yarn, which is prepared by a one-step melt spinning method, characterized in that, The fineness of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤95 dtex, and the yarn unevenness is ≤1.0%; the breaking strength of the fully matte fine denier polyamide 56 pre-oriented yarn is 3.1~4.3 cN / dtex, and the coefficient of variation of breaking strength is ≤3.5%; the breaking elongation is 70~83%, and the coefficient of variation of breaking elongation is ≤3.5%. The one-step melt spinning method includes the following steps: Polyamide 56 melt is fed into the spinning box via a melt booster pump, melt filter, and melt delivery pipeline to form nascent filament; The nascent filament is cooled, oiled, and wound to obtain fully dull fine denier polyamide 56 pre-oriented filament. The titanium dioxide content in the polyamide 56 melt is 1.2-1.8 wt%, the dispersed particle size of the titanium dioxide in the polyamide 56 melt is 0.1-0.6 μm, the proportion of titanium dioxide dispersed particle size of 0.2-0.4 μm is above 98%, and the proportion of titanium dioxide dispersed particle size of 0.2-0.3 μm is above 95%. The temperature of the melt delivery pipeline is 265–290°C; the dynamic viscosity of the polyamide 56 melt from the melt booster pump to the spinning box is 200–350 Pa*s; the temperature of the spinning box is 270–292°C; the pressure of the spinning assembly in the spinning box is 10–25 MPa; and the melt pressure at the inlet of the spinning box is 9–16 MPa.

2. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The titanium dioxide content in the polyamide 56 melt is 1.3 to 1.7 wt%.

3. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The relative viscosity of the polyamide 56 melt is 2.38–2.9; and / or, The polyamide 56 has a melt-terminated amino content of 35–90 mmol / kg; and / or, The equilibrium moisture content of the polyamide 56 melt is 300–900 ppm; and / or, The titanium dioxide content in the polyamide 56 melt is 1.4 to 1.65 wt%.

4. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The melt filter is provided with a filter screen, the size of which is 3-15 μm; and / or, The spinning assembly of the spinning box is equipped with a filter screen, the filter screen having a size of 8–18 μm; and / or, The titanium dioxide content in the polyamide 56 melt is 1.45–1.63 wt%.

5. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 4, characterized in that, The filter screen in the melt filter has a size of 5–13 μm; and / or, The filter screen of the spinning assembly has a size of 10-15 μm.

6. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 4, characterized in that, The filter screen in the melt filter has a size of 8-10 μm.

7. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The temperature of the melt delivery pipeline is controlled to be 268–288°C; and / or, From the melt booster pump to the spinning box, the dynamic viscosity of the polyamide 56 melt is 210–250 Pa*s; and / or, The temperature of the spinning box is 273–290°C.

8. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, From the melt booster pump to the spinning box, the dynamic viscosity of the polyamide 56 melt is controlled to be 220–250 Pa*s; and / or, The temperature of the melt conveying pipeline is 270–286°C; and / or, The temperature of the spinning box is 275–288°C.

9. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The temperature of the melt conveying pipeline is 272–284°C; and / or, The temperature of the spinning box is 277–285°C.

10. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The spinning assembly pressure of the spinning box is 12–22 MPa; and / or, The melt pressure at the inlet of the spinning box is 10-16 MPa.

11. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The spinning assembly pressure of the spinning box is 14–18 MPa; and / or, The melt pressure at the inlet of the spinning box is 11-16 MPa.

12. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The winding takes place between two guide discs, with the nascent yarn passing sequentially through guide discs CR1 and CR2 before being wound into shape.

13. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 12, characterized in that, The CR1 guide wire disc speed is 4200–5500 m / min; and / or, The speed of the CR2 guide wire disc is 4220–5550 m / min.

14. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The dyeing uniformity of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥3.5 grade; and / or, The dyeing double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥95%; and / or, The cake appearance double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥96%.

15. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The unevenness of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤0.9%; and / or, The dyeing uniformity of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥4.0 grade; and / or, The dyeing double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥96%; and / or, The cake appearance double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥97%.

16. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The unevenness of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤0.85%; and / or, The coefficient of variation of the breaking strength of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤3.0%; and / or, The dyeing uniformity of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥4.5 grade; and / or, The dyeing double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥97%; and / or, The double-A ratio of the cake appearance of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥98%.

17. The fully matte fine denier polyamide 56 pre-oriented yarn according to claim 1, characterized in that, The unevenness of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤0.8%; and / or, The coefficient of variation of the breaking strength of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤2.5%; And / or, The coefficient of variation of the elongation at break of the fully matte fine denier polyamide 56 pre-oriented yarn is ≤3.0%; and / or, The dyeing uniformity of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥4.7 grade; and / or, The dyeing double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn is ≥98%; and / or, The appearance double A rate of the fully matte fine denier polyamide 56 pre-oriented yarn cake is ≥99%.

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