Nascent filament, polyamide fiber and preparation method and application of nascent filament

Abstract

The invention discloses a nascent filament, a polyamide fiber and a preparation method and application of the nascent filament and the polyamide fiber. The nascent filament is prepared by the following steps: performing wet spinning on a spinning solution to form the nascent filament; wherein the viscosity of the spinning solution is not lower than 1Pa. S; wherein the spinning solution comprises polyamide and a solvent; the polyamide contains at least one diamine unit and at least one diacid unit, the diacid unit contains at least one aliphatic diacid unit and at least one aromatic diacid unit, and the diamine unit at least contains a pentamethylene diamine unit. The wet spinning technology can be suitable for high-melting-point polyamide resin and is beneficial to industrial large-scale production, the prepared nascent filaments are good in processability, and the polyamide fibers prepared from the nascent filaments have excellent heat resistance, high strength and low shrinkage performance and can adapt to various application scenes.

Description

Technical Field

[0001] The invention relates to the technical field of fiber materials, and in particular to a spun silk, a polyamide fiber, and a preparation method and application thereof. Background Art

[0002] Polyamide fiber is one of the earliest synthetic fibers put into industrial production in the world, and plays a pivotal role in the field of synthetic fibers. There are many types of polyamide fibers, and the most widely used and industrially produced ones are polyamide 6 and polyamide 66. The main applications involve: socks, lace underwear, corsets, sports underwear, wedding dresses, casual jackets, sportswear, raincoats, assault jackets, quick-drying clothes, winter clothing, outdoor tents, sleeping bags, mountaineering bags and other fields; while industrial yarns are widely used in fields such as cords, transmission belts, hoses, ropes, fishing nets, tires, parachutes and so on.

[0003] Polyamide fibers are usually manufactured by melt spinning. However, if the melting point of the polyamide resin itself is high and close to the thermal decomposition temperature, the traditional melt spinning method will cause melt degradation, resulting in spinning drift, broken fibers, and poor fiber mechanical properties. Therefore, for polyamide resins with higher melting points, in order to obtain high-performance polyamide fibers, a more suitable production process needs to be developed. Summary of the invention

[0004] In order to overcome the defects of melt degradation, spinning drift, broken yarns and poor fiber mechanical properties caused by the high melting point of polyamide resin and the close thermal decomposition temperature when the prior art uses melt spinning to manufacture polyamide fibers, the present invention provides a spun yarn, polyamide fiber and a preparation method and application thereof. The polyamide fiber prepared from the spun yarn of the present invention has the performance characteristics of heat resistance, high strength and low shrinkage, and is widely used. The manufacturing method can be applied to polyamide resins with high melting points, which is conducive to industrialized scale-up production.

[0005] The present invention solves the above technical problems through the following technical solutions.

[0006] In a first aspect, the present invention provides a spun silk, which is produced by the following method: wet spinning a spinning solution to form spun silk;

[0007] Wherein, the viscosity of the spinning solution is not less than 1 Pa.s;

[0008] The spinning solution comprises polyamide and a solvent; the polyamide contains at least one diamine unit and at least one diacid unit, the diacid unit contains at least one aliphatic diacid unit and at least one aromatic diacid unit, and the diamine unit contains at least pentamethylenediamine unit.

[0009] Spinning solution

[0010] In the present invention, the viscosity of the spinning solution is preferably 1-100 Pa.s, more preferably 15-50 Pa.s. The viscosity of the spinning solution of the present invention is tested by a rotation method, for example, by referring to the method of GB / T 10247-2008.

[0011] In some specific embodiments, the viscosity of the spinning solution is preferably 15-50 Pa.s, for example, 16.7 Pa.s, 19.5 Pa.s, 19.9 Pa.s, 21.6 Pa.s, 22.6 Pa.s, 24.2 Pa.s, 25.5 Pa.s, 27.6 Pa.s, 29.6, Pa.s, 32.4 Pa.s, 33.4 Pa.s, 34.2 Pa.s, 35.1 Pa.s, 35.5 Pa.s, 36.8 Pa.s, 40.8 Pa.s, 42.5 Pa.s or 43.1 Pa.s.

[0012] In the present invention, the concentration of the spinning solution may be 3%-70%, preferably 5%-55%, more preferably 10-50%, for example 15%, 20%, 22%, 23%, 25%, 27%, 28%, 30%, 31%, 32%, 34%, 35%, 36%, 40%, 45% or 48%, where the percentage is the mass percentage of the polyamide in the spinning solution. If the content of polyamide in the spinning solution is lower than the above range, the viscosity of the spinning solution may be too low; if it exceeds the above range, the viscosity may increase excessively, which is not conducive to spinning.

[0013] The present invention has no particular limitation on the preparation method or reaction conditions of the spinning solution. The polyamide and the solvent may be mixed at -10°C to 100°C until the polyamide is dissolved. The mixing time is not particularly limited.

[0014] Polyamide

[0015] In the present invention, the molar ratio of the diamine unit to the diacid unit may be (0.9-1.2):1, preferably (0.95-1.1):1, for example, 1.05:1.

[0016] In the present invention, the molar ratio of the aliphatic diacid unit to the aromatic diacid unit may be (10-50):(50-90), preferably (20-50):(50-75), for example, 50:50, 30:70 or 35:65.

[0017] In some specific embodiments, the molar percentage of the pentamethylenediamine units to the diamine units is 20%-100%, preferably 20%-70%, for example 50.25%.

[0018] In the present invention, the diamine unit is derived from an aliphatic diamine, preferably butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine or a combination thereof, for example, from pentadecanediamine and / or hexanediamine.

[0019] Wherein, the hexamethylenediamine may be 1,6-hexamethylenediamine.

[0020] Wherein, the pentamethylenediamine may be 1,5-pentamethylenediamine.

[0021] In some specific embodiments, the pentamethylenediamine unit may be derived from bio-based pentamethylenediamine, which refers to pentamethylenediamine synthesized from biomass-derived compounds such as glucose and lysine through enzyme reaction, yeast reaction or fermentation reaction in a monomer synthesis process.

[0022] The biobased content of the biobased pentamethylenediamine can be determined by a method for measuring the radioactive C14 content, such as the standard ASTM-D6866 method of the American Society for Testing and Materials.

[0023] In the present invention, the aliphatic diacid unit is derived from an aliphatic short-chain diacid and / or an aliphatic long-chain diacid.

[0024] In some specific embodiments, the aliphatic short-chain diacid includes oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid or a combination thereof, preferably adipic acid, such as 1,6-hexanedioic acid.

[0025] In some specific embodiments, the aliphatic long-chain diacid includes azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedicarboxylic acid or a combination thereof, preferably sebacic acid, undecanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid or a combination thereof.

[0026] In some specific embodiments, the aliphatic diacid unit is derived from a combination of an aliphatic short-chain diacid and an aliphatic long-chain diacid, wherein the aliphatic short-chain diacid is, for example, adipic acid, and the aliphatic long-chain diacid is, for example, selected from sebacic acid, undecanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid, or a combination thereof.

[0027] In the present invention, the aromatic diacid unit may be derived from an aromatic diacid and / or an aromatic diacid derivative, preferably phthalic acid and / or phthalate.

[0028] In some specific embodiments, the phthalic acid may be one or more of terephthalic acid, isophthalic acid and orthophthalic acid, for example, terephthalic acid.

[0029] In some specific embodiments, the phthalate ester may be terephthalate ester, and preferably, the terephthalate ester is dimethyl terephthalate and / or diethyl terephthalate.

[0030] In some preferred embodiments, the diamine unit is derived from pentamethylenediamine; the aliphatic diacid unit is derived from adipic acid and any one selected from sebacic acid, undecanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid and hexadecanedioic acid; and the aromatic diacid unit is derived from terephthalic acid.

[0031] In some specific embodiments, the diamine units are derived from pentamethylenediamine and hexamethylenediamine, the aliphatic diacid units are derived from adipic acid, and the aromatic diacid units are derived from terephthalic acid.

[0032] In some specific embodiments, the diamine units are derived from 1,5-pentanediamine and 1,6-hexanediamine, the aliphatic diacid units are derived from 1,6-adipic acid, and the aromatic diacid units are derived from terephthalic acid.

[0033] In the present invention, the polyamide can be expressed as polyamide 5XY, or simply referred to as PA5XY, wherein "5" represents pentamethylenediamine units, "X" represents other diamine units, and "Y" represents diacid units.

[0034] In some specific embodiments, the polyamide is a bio-based polyamide 5XY, which contains a diamine unit from bio-based pentamethylenediamine and has the advantage of being renewable in source. Examples of bio-based polyamide 5XY include commercially available polyamides provided by Cathay Biotech Inc. A series of materials, such as 6638, 6308, 6300, 6290, 6635, 6631, 6632, 6520, 5000, 3600, 3601, 3100, 3102, 3300, 3500, 2260, 2262, 1273, 1251 or 1320.

[0035] In some specific embodiments, the relative viscosity of the polyamide may be 1.2-6.0, preferably 2.0-5.2, for example 2.57, 2.73, 3.15, 3.20, 3.27, 3.34, 3.50, 4.20, 4.50, 5.00 or 5.20. The relative viscosity is measured by the Ubbelohde viscometer concentrated sulfuric acid (concentration 96%) method.

[0036] In some specific embodiments, the polyamide may be subjected to a viscosity-increasing treatment before use, wherein the viscosity-increasing treatment is performed to make the viscosity of the polyamide meet the above requirements.

[0037] In some specific embodiments, the melting point of the polyamide may be 250°C-320°C, preferably 260°C-310°C, for example 267°C, 279°C, 275°C, 287°C, 289°C, 298°C or 300°C.

[0038] In the present invention, the polyamide may further contain additives, and the content of the additives may be selected according to actual conditions.

[0039] The additives may include heat stabilizers, antioxidants, fluorescent brighteners, pigments, dyes, UV inhibitors, flame retardants, flow modifiers, organic fillers, inorganic fillers, silica powder, powder binders, carbon nanotubes or combinations thereof, such as heat stabilizers and / or antioxidants.

[0040] The heat stabilizer may be phosphoric acid, phosphorous acid, trimethyl phosphite, triphenyl phosphite, trimethyl phosphate, triphenyl phosphate, sodium hypophosphite, zinc hypophosphite, calcium hypophosphite, potassium hypophosphite or a combination thereof, such as sodium hypophosphite.

[0041] Wherein, the antioxidant is selected from one or more of hindered phenol antioxidants, hindered amine antioxidants and phosphite antioxidants;

[0042] The hindered phenol antioxidant can be purchased commercially. Preferably, the hindered phenol antioxidant is selected from antioxidant 1098 and / or antioxidant 1010, such as antioxidant 1098.

[0043] The phosphite antioxidant can be purchased commercially. Preferably, the phosphite antioxidant is selected from antioxidant 168 and / or antioxidant S9228.

[0044] Preferably, the antioxidant is selected from one or more of the commercially available antioxidant 168, antioxidant 1098, antioxidant 1010 and antioxidant S9228.

[0045] In some specific embodiments, the polyamide contains sodium hypophosphite and antioxidant 1098.

[0046] In the above specific implementation, the content of sodium hypophosphite may be 0.03wt%, and the percentage is the percentage of the mass of sodium hypophosphite to the sum of the masses of the various raw materials of the polyamide.

[0047] In the above specific implementation, the content of the antioxidant 1098 may be 0.3 wt %, where the percentage is the percentage of the mass of the antioxidant 1098 to the sum of the masses of the various raw materials of the polyamide.

[0048] In some preferred embodiments, the polyamide is prepared by the following method: after mixing monomers and water to obtain a polyamide salt solution, controlling the temperature and pressure to perform a polymerization reaction to obtain a melt, and then subjecting the melt to stranding and pelletizing to obtain the polyamide; wherein the monomers include at least one diamine and at least one diacid, the diacid contains at least one aliphatic diacid and at least one aromatic diacid, and the diamine contains at least pentamethylenediamine.

[0049] In some specific embodiments, the polyamide can be prepared by the following method:

[0050] S1, mixing monomers and water to prepare a polyamide salt solution, and preparing a polyamide salt aqueous solution with a concentration of 30-75wt%; wherein the monomers include at least one diamine and at least one diacid, the diacid contains at least one aliphatic diacid and at least one aromatic diacid, and the diamine contains at least pentamethylenediamine;

[0051] S2. In a nitrogen or inert gas atmosphere, heat the polyamide salt aqueous solution to a temperature of 230-310° C. and a reaction pressure of 0.7-2.5 MPa, and maintain for 60-180 min; then vent to normal pressure and raise the temperature to 260-340° C.; evacuate to reduce the pressure to -(0.02-0.08) MPa, and maintain for 0.1-120 minutes to obtain a melt, and then strand and pelletize to obtain the polyamide.

[0052] Solvents

[0053] In the present invention, the solvent may be a conventional solvent in the art that can dissolve the polyamide, for example, dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), sodium thiocyanate aqueous solution, zinc chloride aqueous solution, nitric acid, sulfuric acid, formic acid, acetic acid, dichloromethane, benzene, toluene, xylene, methanol, ethanol, phenol, chloroform, which may be used alone or in combination of two or more, or may be mixed with water.

[0054] In some specific embodiments, the solvent is formic acid, dimethylformamide, dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone.

[0055] In some specific embodiments, when the solvent is mixed with water, the percentage of the solvent in the total mass of the solvent and water is 50-99.99 wt %. The percentage of the solvent in the total mass of the solvent and water can be adjusted by diluting with water or evaporating and concentrating.

[0056] Wet spinning

[0057] In the present invention, the wet spinning process may generally include the following steps: spraying and coagulating the spinning solution as described above.

[0058] In some embodiments, wet spinning comprises the following steps: the spinning solution as described above enters a coagulation bath through a spinneret. In some embodiments, the temperature of the spinning solution may be 5-100°C, preferably 10-80°C, more preferably 15-45°C, for example, 20°C, 25°C, 30°C, 35°C or 40°C.

[0059] In some specific embodiments of the present invention, the temperature of the spinning solution is 25°C, 40°C, 45°C, 50°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0060] In some embodiments, the spinning device can use conventional equipment in the art, and the spinning device can generally include a spinneret or a spinneret and a spinneret. When the spinning device includes a spinneret and a spinneret, the spinneret is arranged on the spinneret.

[0061] In some specific embodiments, the number of holes of the spinneret may be 5-100000f, preferably 10-50000f, for example, 40f, 50f, 60f, 80f, 100f, 300f or 500f.

[0062] In some specific embodiments, the spinning rate of the spinning may be 0.1-6 m / min, preferably 1-3 m / min, for example, 1.5 m / min, 1.61 m / min, 1.65 m / min, 1.71 m / min, 1.72 m / min, 1.82 m / min, 1.84 m / min, 1.85 m / min, 1.87 m / min, 1.89 m / min, 1.92 m / min, 1.95 m / min, 1.96 m / min, 2.05 m / min, 2.09 m / min, 2.31 m / min or 2.35 m / min.

[0063] In some specific embodiments, the spinning process further includes the steps of degassing and filtering the spinning solution before spinning.

[0064] The degassing can be performed by conventional methods in the art, such as vibration degassing or adding a defoaming agent for degassing.

[0065] The filtration may be carried out by conventional methods in the art, and the purpose of the filtration is to remove unreacted impurities, large colloid particles, etc. in the solution, avoid blocking the spinneret, and improve the spinning performance.

[0066] In some embodiments, the coagulation bath comprises water and / or a coagulant.

[0067] Among them, the coagulant is preferably one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, sodium thiocyanate aqueous solution, zinc chloride aqueous solution, nitric acid, sulfuric acid, formic acid, acetic acid, dichloromethane, benzene, toluene, xylene, methanol, ethanol, phenol and chloroform.

[0068] In some specific embodiments, the coagulation bath comprises water and a coagulant, wherein the concentration of the coagulant is 0.1%-55%, more preferably 0.1%-45%, for example 15%, 18%, 20%, 22%, 24%, 25%, 28% or 30%, where the percentage is the percentage of the solvent to the total volume of the coagulation bath.

[0069] In some embodiments, the coagulation bath comprises, for example, water and formic acid, water and DMF, water and DMAc, water and DMSO, or water and NMP.

[0070] In some embodiments, the temperature of the coagulation bath is 3-80°C, preferably 10-60°C, more preferably 15-45°C, for example 20°C, 25°C, 30°C, 35°C or 40°C.

[0071] In some specific embodiments, the fiber surface of the primary silk is flat, and the cross section is a porous skin-core structure.

[0072] In a second aspect, the present invention provides a method for preparing a spun silk as described above, comprising the following steps: forming spun silk by wet spinning a spinning solution; wherein the viscosity of the spinning solution is not less than 1 Pa.s; the spinning solution comprises a polyamide and a solvent; the polyamide contains at least one diamine unit and at least one diacid unit, the diacid unit contains at least one aliphatic diacid unit and at least one aromatic diacid unit, and the diamine unit contains at least pentamethylenediamine unit.

[0073] Wherein, the spinning solution, the polyamide, the wet spinning, etc. are as defined above.

[0074] In a third aspect, the present invention provides a polyamide fiber, which is produced by the following method: drawing, washing, heat treating, oiling and winding the above-mentioned spun yarn.

[0075] In some specific embodiments, the drafting multiple can be adjusted according to the actual fiber use, and the drafting multiple is, for example, 1-20 times.

[0076] For general fibers for clothing, the drafting multiple is 5-10 times, preferably 6-9 times.

[0077] For industrial or technical fibers, the drafting multiple is 10-18 times, preferably 12-17 times.

[0078] In some specific embodiments, the stretching multiple is, for example, 4.9 times, 5.2 times, 5.4 times, 5.7 times, 5.9 times, 6.1 times, 6.3 times, 6.4 times, 6.8 times, 6.9 times, 7.0 times, 7.1 times, 7.2 times, 7.5 times, 8.1 times, 8.6 times or 8.9 times.

[0079] In some specific embodiments, the stretching method of the stretching can be wet heat stretching or dry heat stretching, or a combination of wet heat stretching and dry heat stretching, without particular limitation.

[0080] In some specific embodiments, the temperature of the wet heat stretching is 20-95° C., preferably 25-85° C. For example, the temperature of the wet heat stretching is 70° C., 80° C., 85° C., 88° C., 90° C., 92° C. or 93° C.

[0081] In some specific embodiments, the temperature of the dry heat stretching is 96-260° C., preferably 100-250° C. For example, the temperature of the dry heat stretching is 210° C., 220° C., 225° C., 230° C. or 242° C.

[0082] In some specific embodiments, the stretching method is a combination of wet heat stretching and dry heat stretching.

[0083] In some specific embodiments, the washing detergent may be water and / or ethanol, and the purpose of the washing is to remove organic solvents in the spun fibers and impurities attached to the fiber surface.

[0084] In some specific embodiments, the heat treatment includes drying and heat setting. The purpose of the drying is to remove excess moisture in the fiber. The purpose of the heat setting process is to eliminate the internal stress generated in the fiber during the stretching process, relax the macromolecules to a certain extent, improve the deformation recovery ability of the fiber, and maintain the state during setting.

[0085] Wherein, the drying temperature may be 25-250°C, preferably 50-220°C, for example, 100°C, 115°C or 120°C;

[0086] The heat setting temperature may be 100-280°C, preferably 130-260°C, for example 140°C, 150°C, 160°C, 165°C, 168°C, 170°C, 175°C or 180°C.

[0087] The heat setting can be carried out in a conventional manner in the art, preferably by high temperature and high pressure steam or a hot box.

[0088] In some specific embodiments, the oil concentration of the oiling may be 1%-5%, preferably 1.5%-3%, for example 1.70%, 1.72%, 1.79%, 1.80%, 1.85%, 1.90%, 2.00% or 2.15%, where the percentage is the mass percentage of oil to primary silk.

[0089] In some specific embodiments, the winding speed is 10-1000 m / min, preferably 20-700 m / min, more preferably 30-500 m / min, for example, 50 m / min, 80 m / min, 85 m / min, 86 m / min, 90 m / min, 98 m / min, 100 m / min, 105 m / min, 106 m / min, 110 m / min, 116 m / min or 120 m / min.

[0090] In some specific embodiments, the number of broken monofilaments of the polyamide fiber is 0-6 times / 24h, preferably 0-4 times / 24h, more preferably 0-2 times / 24h, for example 0.2 times / 24h, 0.3 times / 24h, 0.5 times / 24h or 1 time / 24h.

[0091] In some specific embodiments, the breaking strength of the polyamide fiber is 2.0-20.0 cN / dtex, preferably 3.5-15.0 cN / dtex, and more preferably 4.5-10.0 cN / dtex. The breaking strength is measured according to GB / T14344-2008.

[0092] In some specific embodiments, the breaking strength of the polyamide fiber is 3.42 cN / dtex, 3.59 cN / dtex, 3.62 cN / dtex, 3.69 cN / dtex, 3.77 cN / dtex, 3.95 cN / dtex, 4.28 cN / dtex, 4.59 cN / dtex, 4.64 cN / dtex, 4.71 cN / dtex, 4.90 cN / dtex, 4.94 cN / dtex, 5.37 cN / dtex, 3.53 cN / dtex, 3.85 cN / dtex, 4.32 cN / dtex, 5.19 cN / dtex or 5.26 cN / dtex.

[0093] In some specific embodiments, the elongation at break of the polyamide fiber is 1-50%, preferably 3-40%, more preferably 5-30%. The elongation at break is measured according to GB / T 14344-2008.

[0094] In some specific embodiments of the present invention, the elongation at break of the polyamide fiber is 32.63%, 34.74%, 34.81%, 35.93%, 36.10%, 36.43%, 36.50%, 36.68%, 37.52%, 37.68%, 37.73%, 38.80%, 38.93%, 39.20%, 39.37%, 39.53%, 40.94%, 41.20% or 43.50%.

[0095] In some specific embodiments, the initial modulus of the polyamide fiber is 20-80 cN / dtex, preferably 25-70 cN / dtex, and more preferably 30-60 cN / dtex, for example, 38.90 cN / dtex, 39.40 cN / dtex, 39.81 cN / dtex, 40.76 cN / dtex, 42.30 cN / dtex, 42.59 cN / dtex, 43.24 cN / dtex, 43.50 cN / dtex, 43.71 cN / dtex, 44.10 cN / dtex, 44.70 cN / dtex, 44.90 cN / dtex, 45.90 cN / dtex, 47.60 cN / dtex, 49.70 cN / dtex, 52.14 cN / dtex or 54.43 cN / dtex. The initial modulus is measured according to GB / T 14344-2008.

[0096] In some specific embodiments, the boiling water shrinkage of the polyamide fiber is 3-11%, preferably 3-10%, and more preferably 3-8%. The boiling water shrinkage is measured with reference to GB / 6505-2008 "Test method for thermal shrinkage of chemical fiber filaments", and the specific calculation formula is as follows: boiling water shrinkage = ((length before heat treatment - length after heat treatment) / length before heat treatment) * 100%.

[0097] In some specific embodiments, the boiling water shrinkage of the polyamide fiber is 5.04%, 5.13%, 5.45%, 5.67%, 6.84%, 7.07%, 7.26%, 7.49%, 7.58%, 7.62%, 8.59%, 9.35%, 9.62%, 9.73%, 10.02%, 10.17%, 10.34%, 10.52% or 10.95%.

[0098] In some specific embodiments, the 177°C, 2 min dry heat shrinkage of the polyamide fiber is 1.0-7.0%, preferably 1.5-6.0%, more preferably 2.0-5.0%. The dry heat shrinkage is carried out in accordance with FZ / T50004, and the heat treatment temperature is 180°C.

[0099] In some specific embodiments, the 177°C, 2 min dry heat shrinkage of the polyamide fiber is 2.27%, 2.45%, 2.93%, 2.97%, 3.67%, 3.93%, 4.10%, 4.29%, 4.31%, 4.38%, 5.24%, 6.03%, 6.42%, 6.56%, 6.75%, 6.98%, 7.16%, 7.09% or 7.30%.

[0100] In some specific embodiments, the orientation degree of the polyamide fiber is 0.4-0.9, preferably 0.5-0.8, more preferably 0.6-0.8, for example, 0.6015, 0.6025, 0.6128, 0.6172, 0.6381, 0.6423, 0.6451, 0.6521, 0.6563, 0.6579, 0.6593, 0.6599, 0.6686, 0.6738, 0.6824, 0.6867, 0.6882 or 0.7078.

[0101] In a fourth aspect, the present invention provides a method for preparing the polyamide fiber as described above, comprising the following steps: drawing, washing, heat treating, oiling and winding the spun yarn as described above.

[0102] In the present invention, the drawing, washing, heat treatment, oiling and winding are as defined above.

[0103] In a fifth aspect, the present invention provides a use of the spun silk or polyamide fiber as described above in textiles.

[0104] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0105] The reagents and raw materials used in the present invention are commercially available.

[0106] The positive and progressive effects of the present invention are:

[0107] (1) The surface of the raw silk of the present invention is smooth, and its cross section presents a porous skin-core structure. It has good strength and good processability, and can be used for the preparation of polyamide fibers.

[0108] (2) The present invention adopts a wet spinning process to prepare primary silk, which avoids the problems of melt degradation caused by the high melting point of polyamide resin, close to the thermal decomposition temperature, leading to spinning drift, broken silk and poor mechanical properties of the fiber. It can be used for high melting point polyamide resin, which is conducive to industrial scale-up production.

[0109] (3) The polyamide fiber prepared from the primary silk of the present invention has high breaking strength, breaking elongation and initial modulus, and low boiling water shrinkage, dry heat shrinkage and number of single filament breakage. It has excellent heat resistance, high strength and low shrinkage properties and can adapt to various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0110] Figure 1 This is the SEM image of the spun silk prepared in Example 1. DETAILED DESCRIPTION

[0111] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the descriptions therein are essentially for illustrative purposes rather than for limiting the present invention. The experimental methods in the following examples that do not specify specific conditions are selected according to conventional methods and conditions, or according to the product specifications.

[0112] The raw materials used in the embodiments and comparative examples are as follows:

[0113] Raw material 1: bio-based polyamide resin PA5XY, brand E-6290, relative viscosity of the resin after thickening is 3.34, melting point is 289°C.

[0114] Raw material 2: bio-based polyamide resin PA5XY, brand E-6631, relative viscosity of the resin after thickening is 5.0, melting point is 267°C.

[0115] Raw material 3: bio-based polyamide resin PA5XY, brand E-6632, relative viscosity of the resin after thickening is 5.2, melting point is 279°C.

[0116] Raw material 4: bio-based polyamide resin PA5XY, brand E-6635, relative viscosity of the resin after thickening is 3.2, melting point is 298°C.

[0117] In the above raw materials 1-4, the specific method of increasing the viscosity of the resin is to put the polyamide resin into a drying oven and dry it under vacuum at 160-180° C. for 100-180 hours. The temperature and drying time are selected according to the target viscosity.

[0118] Raw material 5: bio-based polyamide resin PA5XY, brand E-6290, relative viscosity 2.57, melting point 289°C.

[0119] Raw material 6: bio-based polyamide resin PA5XY, brand E-6631, relative viscosity 3.27, melting point 267°C.

[0120] Raw material 7: bio-based polyamide resin PA5XY, brand E-6632, relative viscosity 3.15, melting point 279°C.

[0121] Raw material 8: bio-based polyamide resin PA5XY, brand E-6635, relative viscosity 2.73, melting point 298°C.

[0122] Raw material 9: bio-based polyamide resin PA5XY, prepared by the following method: 0.505 mol 1,5-pentanediamine, 0.50 mol 1,6-hexanediamine, 0.50 mol 1,6-hexanediamine, 0.50 mol terephthalic acid, 0.03 wt% sodium hypophosphite, 0.3 wt% antioxidant 1098 and water were mixed evenly, heated to 80°C, maintained for 1.5 h, and continued to heat to 130°C to obtain a polyamide salt solution with a concentration of 65 wt%; heated to 250°C again in a nitrogen atmosphere, and maintained at a pressure of 2.5 MPa for 1.5 h; vented to normal pressure and the temperature was increased to 330°C at the same time; evacuated to -0.07 MPa, maintained for 40 min to obtain a polyamide melt, cooled and pelletized to obtain a polyamide resin with a melting point of 275°C and a relative viscosity of 3.5 after the resin was thickened.

[0123] Raw material 10: bio-based polyamide resin PA5XY, the preparation method adopted is the same as that of raw material 9, the difference is that the raw materials are: 0.505 mol 1,5-pentanediamine, 0.50 mol 1,6-hexanediamine, 0.30 mol 1,6-adipic acid, 0.70 mol terephthalic acid, 0.03 wt% sodium hypophosphite, 0.3 wt% antioxidant 1098, to obtain polyamide resin, the melting point of the resin after thickening is 300°C, and the relative viscosity is 4.5.

[0124] Raw material 11: bio-based polyamide resin PA5XY, the preparation method adopted is the same as that of raw material 9, the difference is that the raw materials are: 1.005 mol 1,5-pentanediamine, 0.35 mol 1,6-hexanedioic acid, 0.65 mol terephthalic acid, 0.03 wt% sodium hypophosphite, 0.3 wt% antioxidant 1098, to obtain polyamide resin, the melting point of the resin after thickening is 287°C, and the relative viscosity is 4.2.

[0125] The melting point of each resin in the above raw materials is measured by differential scanning calorimetry (DSC).

[0126] Example 1

[0127] (1) Preparing spun silk: mixing raw material 1 (brand name: E-6290) with solvent formic acid until raw material 1 is completely dissolved to obtain a spinning solution, filtering and defoaming the spinning solution, and then extruding the spinning solution through a spinneret of a spinneret into a coagulation bath to form spun silk;

[0128] Among them, the relative viscosity of raw material 1 is 3.34 Pa.s, the melting point is 289°C, the spinning solution concentration is 25wt%, and the viscosity is 24.2 Pa.s;

[0129] The temperature of the spinning solution was 40°C, the number of spinneret holes was 80f, and the spinning rate was 1.65 m / min.

[0130] The coagulation bath is composed of a coagulant and water, the coagulant is formic acid, the temperature of the coagulation bath is 25°C, and the solvent concentration in the coagulation bath is 15wt%;

[0131] (2) preparing polyamide fibers: drawing, washing, heat treating, oiling, and winding the spun yarn obtained in step (1) to obtain polyamide fibers;

[0132] Among them, drawing includes wet heat traction and dry heat traction, the temperature of wet heat traction is 80°C, the temperature of dry heat traction is 220°C, and the traction multiple is 7.0 times; the detergent used for washing is water; the heat treatment includes drying and heat setting, and the specific steps of the heat treatment are as follows: after drying at 120°C, use a hot box for heat setting at 150°C; the oiling concentration is 1.80%; the winding speed is 90m / min.

[0133] Example 2-19

[0134] The raw materials and process parameters for preparing the spun silk in Examples 2-19 are shown in Table 1, the process parameters for preparing the polyamide fiber are shown in Table 2, and the preparation steps of the spun silk and polyamide fiber are the same as in Example 1.

[0135] Comparative Example 1

[0136] The resin raw material is the same as that in Example 1. The polyamide raw material is put into a twin-screw extruder by a melt spinning method. The screw temperatures are set to 295°C, 305°C, 310°C, and 320°C, respectively. The spinning box temperature is 318°C, the spinning speed is 3000m / min, the post-drawing multiple is 3.2 times, the drawing temperature is 100°C, and the heat setting temperature is 240°C.

[0137] Comparative Examples 2-4

[0138] The raw materials and spinning process parameters used in Comparative Examples 2-4 are shown in Table 1, and the rest are the same as Comparative Example 1.

[0139] Comparative Example 5

[0140] The raw materials and process parameters for preparing the spun silk in Comparative Example 5 are shown in Table 1, the process parameters for preparing the polyamide fiber are shown in Table 2, and the preparation steps of the spun silk and polyamide fiber are the same as those in Example 1.

[0141] The strength of the spun yarn obtained in Comparative Example 5 is too low to be subjected to subsequent hot drawing and winding processes, and polyamide fiber cannot be obtained.

[0142] Table 1 Raw materials and process parameters for preparing spun silk in Examples 1-19 and Comparative Examples 1-5

[0143]

[0144] Table 2 Process parameters for preparing polyamide fibers in Examples 1-19 and Comparative Examples 1-4

[0145]

[0146]

[0147] Effect Example

[0148] The polyamide fibers obtained in Examples 1-19 and Comparative Examples 1-4 were tested as follows:

[0149] (1) Breaking strength, initial modulus and elongation at break: measured in accordance with GB / T 14344-2008.

[0150] (2) Dry heat shrinkage: in accordance with FZ / T 50004, the heat treatment temperature is 180℃.

[0151] (3) Relative viscosity: The relative viscosity is measured by the concentrated sulfuric acid method using an Ubbelohde viscometer, and the steps are as follows: accurately weigh 0.5±0.0002 g of the dried polyamide resin or fiber sample, add 50 mL of concentrated sulfuric acid (96%) to dissolve, and measure and record the flow time t0 of the concentrated sulfuric acid and the flow time t of the polyamide 56 chips or their staple fiber sample solution in a 25°C constant temperature water bath. The relative viscosity calculation formula is: relative viscosity VN = t / t0; t—solution flow time; t0—solvent flow time.

[0152] (6) Orientation degree: measured by fiber sonic orientation instrument.

[0153] (7) Boiling water shrinkage: The boiling water shrinkage is determined according to GB / 6505-2008 “Test method for thermal shrinkage of chemical fiber filaments”, boiling water shrinkage = ((length before heat treatment - length after heat treatment) / length before heat treatment) * 100%.

[0154] (8) Number of single-filament breakages: manually counted.

[0155] Table 3 Mechanical properties data of polyamide fibers prepared in Examples 1-19 and Comparative Examples 1-4

[0156]

[0157] Figure 1The SEM image of the spun yarn obtained in Example 1 shows that the surface of the spun yarn is flat. Combined with Table 3, it can be seen that the breaking strength of the polyamide fibers obtained in Examples 1-19 is between 3.42-5.26 cN / dtex, the breaking elongation is between 32.63%-43.50%, the initial modulus is between 38.90-54.43 cN / dtex, the boiling water shrinkage is between 5.04%-10.95%, the 177°C, 2min dry heat shrinkage is between 2.27%-7.30%, the orientation degree is between 0.6015-0.7078, and the number of single filament breakage is between 0.2-1 times / 24h, and the fibers have excellent mechanical properties.

[0158] By comparing Example 1 and Comparative Example 5, it can be seen that when the viscosity of the spinning solution is lower than 1 Pa.s, specifically 0.39 Pa.s in Comparative Example 5, the strength of the spun yarn obtained at this time is too low to carry out subsequent hot drawing and winding processes, and cannot be used for the preparation of polyamide fibers.

[0159] Comparative Examples 1-4 are polyamide fibers prepared by melt spinning, wherein the raw materials used in Comparative Example 1 are the same as those in Example 1, but the breaking strength, breaking elongation, and initial modulus of the polyamide fiber prepared in Comparative Example 1 are lower than those in Example 1, and its boiling water shrinkage, 177°C, 2min dry heat shrinkage, and number of single filament breakages are higher than those in Example 1. It can be seen that the performance of the polyamide fiber prepared in Comparative Example 1 is worse than that in Example 1 in all aspects.

[0160] The raw materials used in Comparative Example 2 are the same as those in Example 2, but the breaking strength, breaking elongation, initial modulus and orientation degree of the polyamide fiber prepared in Comparative Example 2 are lower than those in Example 2, and its boiling water shrinkage, 177°C, 2min dry heat shrinkage and the number of single filament breakages are higher than those in Example 2. It can be seen that the various performances of the polyamide fiber prepared in Comparative Example 2 are far inferior to those of Example 2.

[0161] The raw materials used in Comparative Example 3 are the same as those in Example 3, but the breaking strength, breaking elongation, initial modulus and orientation degree of the polyamide fiber prepared in Comparative Example 3 are lower than those in Example 3, and its boiling water shrinkage, 177°C, 2min dry heat shrinkage and the number of single filament breakages are higher than those in Example 3. It can be seen that the various performances of the polyamide fiber prepared in Comparative Example 3 are worse than those in Example 3.

[0162] The raw materials used in Comparative Example 4 are the same as those in Example 15, but the breaking strength, breaking elongation and initial modulus of the polyamide fiber prepared in Comparative Example 4 are lower than those in Example 15, and its boiling water shrinkage, 177°C, 2min dry heat shrinkage and the number of single filament breakage are higher than those in Example 15. It can be seen that the performance of the polyamide fiber prepared in Comparative Example 4 is worse than that in Example 15.

[0163] The optional embodiments of the present invention are described above to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. After reading the present specification, those skilled in the art can easily think of the modification or alternative of the technical solution of the present invention that can achieve the purpose of the present invention according to the common knowledge in the chemical field, and those skilled in the art should understand that the modification or alternative derived from these embodiments will fall within the scope of the present invention.

Claims

1. A raw silk, characterized in that: The method is as follows: a spinning solution is wet-spinned to form primary fibers; Wherein, the viscosity of the spinning solution is not less than 1 Pa.s; The spinning solution comprises polyamide and a solvent; the polyamide contains at least one diamine unit and at least one diacid unit, the diacid unit contains at least one aliphatic diacid unit and at least one aromatic diacid unit, and the diamine unit contains at least pentamethylenediamine unit.

2. The spun silk according to claim 1, characterized in that: The molar ratio of the diamine unit to the diacid unit is (0.9-1.2):1, preferably (0.95-1.1):1; and / or, the molar ratio of the aliphatic diacid unit to the aromatic diacid unit is (10-50):(50-90), preferably (20-50):(50-75); And / or, the molar percentage of the pentamethylenediamine units to the diamine units is 20%-100%, preferably 20%-70%.

3. The spun silk according to claim 1, characterized in that: The diamine unit is derived from an aliphatic diamine, preferably butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine or a combination thereof; Wherein, the pentamethylenediamine is preferably bio-based pentamethylenediamine; the pentamethylenediamine is preferably 1,5-pentamethylenediamine; the hexamethylenediamine is preferably 1,6-hexamethylenediamine; and / or, the aliphatic diacid unit is derived from an aliphatic short-chain diacid and / or an aliphatic long-chain diacid; Wherein, the aliphatic short-chain diacid preferably includes oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid or a combination thereof, more preferably adipic acid; The aliphatic long-chain diacid preferably includes azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedicarboxylic acid or a combination thereof, and more preferably includes sebacic acid, undecanedicarboxylic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedicarboxylic acid, hexadecanedioic acid or a combination thereof; and / or, the aromatic diacid unit is derived from an aromatic diacid and / or an aromatic diacid derivative, preferably phthalic acid and / or a phthalate; Wherein, the phthalic acid is preferably one or more of terephthalic acid, isophthalic acid and phthalic acid; The phthalate ester is preferably terephthalate ester, and more preferably, the terephthalate ester is dimethyl terephthalate and / or diethyl terephthalate.

4. The spun silk according to claim 1, characterized in that: The viscosity of the spinning solution is 1-100 Pa.s, preferably 15-50 Pa.s; and / or, the concentration of the spinning solution is 3%-70%, preferably 5%-55%, more preferably 10%-50%, where the percentage is the mass percentage of the polyamide in the spinning solution; And / or, the relative viscosity of the polyamide is 1.2-6.0, preferably 2.0-5.2; and / or, the melting point of the polyamide is 250°C-320°C, preferably 260°C-310°C; and / or, the polyamide further comprises an additive; Wherein, the additive preferably includes a heat stabilizer, an antioxidant, a fluorescent brightener, a pigment, a dye, an anti-UV agent, a flame retardant, a flow modifier, an organic filler, an inorganic filler, silica powder, a powder binder, a carbon nanotube or a combination thereof; Wherein, the heat stabilizer is preferably phosphoric acid, phosphorous acid, trimethyl phosphite, triphenyl phosphite, trimethyl phosphate, triphenyl phosphate, sodium hypophosphite, zinc hypophosphite, calcium hypophosphite, potassium hypophosphite or a combination thereof; Wherein, the antioxidant is preferably selected from one or more of hindered phenol antioxidants, hindered amine antioxidants and phosphite antioxidants; Wherein, the antioxidant is preferably one or more of antioxidant 168, antioxidant 1098, antioxidant 1010 and antioxidant S9228; And / or, the solvent is one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, sodium thiocyanate aqueous solution, zinc chloride aqueous solution, nitric acid, sulfuric acid, formic acid, acetic acid, dichloromethane, benzene, toluene, xylene, methanol, ethanol, phenol and chloroform.

5. The spun silk according to claim 1, characterized in that: The wet spinning process comprises the following steps: spinning and coagulating the spinning solution. Preferably, the wet spinning process comprises the following steps: the spinning solution enters a coagulation bath through a spinneret; Wherein, the coagulation bath preferably comprises water and / or a coagulant; The coagulation bath comprises water and a coagulant, wherein the concentration of the coagulant is preferably 0.1%-55%, more preferably 0.1%-45%, and the percentage is the percentage of the coagulant to the total volume of the coagulation bath; the coagulant is preferably one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, sodium thiocyanate aqueous solution, zinc chloride aqueous solution, nitric acid, sulfuric acid, formic acid, acetic acid, dichloromethane, benzene, toluene, xylene, methanol, ethanol, phenol and chloroform; Wherein, the temperature of the coagulation bath is preferably 3-80°C, more preferably 10-60°C, and preferably 15-45°C; Wherein, the spinning equipment preferably includes a spinneret or a spinneret and a spinneret plate; the number of holes of the spinneret plate is preferably 5-100000f, more preferably 10-50000f; Wherein, the spinning rate of the spinning is 0.1-6 m / min, preferably 1-3 m / min; Wherein, before the spinning, it is preferred that the spinning solution is degassed and filtered; the degassed step is preferably performed by vibration degassed or by adding a defoaming agent; And / or, the temperature of the spinning solution is 5-100°C, preferably 10-80°C, more preferably 15-45°C.

6. A method for preparing primary silk according to any one of claims 1 to 5, characterized in that: It includes the following steps: The spinning solution is wet-spun to form primary filaments; wherein the viscosity of the spinning solution is not less than 1 Pa.s; the spinning solution comprises polyamide and a solvent; the polyamide contains at least one diamine unit and at least one diacid unit, the diacid unit contains at least one aliphatic diacid unit and at least one aromatic diacid unit, and the diamine unit contains at least pentamethylenediamine unit.

7. A polyamide fiber, characterized in that: The method is produced by drawing, washing, heat treating, oiling and winding the spun silk according to any one of claims 1 to 5.

8. The polyamide fiber according to claim 7, characterized in that The stretching method of the stretching is wet heat stretching and / or dry heat stretching; The temperature of the wet heat stretching is preferably 20-95°C, more preferably 25-85°C; Wherein, the temperature of the dry heat drawing is preferably 96-260°C, more preferably 100-250°C; And / or, the drafting multiple is 1-20 times; And / or, the washing detergent is water and / or ethanol; and / or, the heat treatment comprises drying and heat setting; Wherein, the drying temperature is preferably 25-250°C, more preferably 50-220°C; Wherein, the heat setting temperature is preferably 100-280°C, more preferably 130-260°C; Wherein, the heat setting is preferably carried out by high temperature and high pressure steam or a hot box; And / or, the oil concentration of the oiling is 1%-5%, preferably 1.5%-3%; And / or, the winding speed is 10-1000 m / min, preferably 20-700 m / min, more preferably 30-500 m / min.

9. A method for preparing polyamide fiber according to claim 7 or 8, characterized in that: The method comprises the following steps: drawing, washing, heat treating, oiling and winding the spun silk.

10. Use of the spun silk according to any one of claims 1 to 5 or the polyamide fiber according to claim 7 or 8 in textiles.

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