CN118186612A

CN118186612A - Polyarylate fine denier fiber and preparation method thereof

Info

Publication number: CN118186612A
Application number: CN202410365403.XA
Authority: CN
Inventors: 张东宝; 邵彩萍; 徐良; 于冉; 刘彦宏
Original assignee: Ningxia Qingyan Polymer New Material Co ltd
Current assignee: Ningxia Qingyan Polymer New Material Co ltd
Priority date: 2024-03-28
Filing date: 2024-03-28
Publication date: 2024-06-14

Abstract

The invention discloses a polyarylate fine denier fiber and a preparation method thereof, and relates to the technical field of fiber preparation, wherein the method firstly takes a polyarylate polymer as a raw material to prepare the polyarylate polymer in a molten state; spinning the polyarylate polymer in a molten state to obtain melt spinning; cooling the melt spinning, and then coiling to obtain polyarylate fiber precursor; unreeling the polyarylate fiber precursor, and performing heat treatment to obtain the polyarylate fine denier fiber. The method ensures that the polyarylate fiber precursor is formed rapidly and stably by controlling the spinning temperature and the rapid cooling temperature in the spinning process, and simultaneously enhances the strength of the polyarylate fiber by the heat treatment process, thereby finally obtaining the polyarylate fine denier fiber. The preparation process is simple, the production efficiency is high, and the method for stably producing the polyarylate fine denier fiber is provided, so that the raw material supply requirements of clothing and industrial applications are met.

Description

Polyarylate fine denier fiber and preparation method thereof

Technical Field

The application relates to the technical field of fiber preparation, in particular to a polyarylate fine denier fiber and a preparation method thereof.

Background

Polyarylate fibers are widely used in general industrial materials due to their high strength, heat resistance, creep resistance and chemical resistance. At present, the specification of the polyarylate fiber is mainly single fiber 5D, and less and finer polyarylate fibers are appeared. For common superfine fibers, the preparation method mostly adopts a direct spinning method and a composite spinning method. The direct spinning method is a method of spinning by reducing the amount of polymer discharged from each hole provided in a spinning head as much as possible, and then performing high drawing; the composite spinning method is a split type composite spinning method in which a composite fiber composed of polymers having 2 or more components which are not compatible with each other is spun, and then the polymers are split into chips by the action of a chemical solution, impact or the like to obtain a very fine fiber.

Both of the above methods have a disadvantage in that the direct spinning method is impossible to stretch at high magnification as in the usual thermoplastic polymers when used for the spinning of polyarylate fibers because of low elongation at break; in the composite spinning method, a special spinning nozzle having a complicated structure, a special process for elution, separation, or the like is required at the stage of melt spinning, and therefore, there is a problem that the cost is extremely high in industrial production.

Disclosure of Invention

The application provides a polyarylate fine denier fiber and a preparation method thereof, which are used for solving the technical problem that the polyarylate fine denier fiber cannot be stably manufactured at present.

In a first aspect, the present invention provides a method for preparing a polyarylate fine denier fiber comprising the steps of:

preparing a polyarylate polymer in a molten state by taking the polyarylate polymer as a raw material;

spinning the polyarylate polymer in a molten state to obtain melt spinning;

Cooling the melt spinning, and then coiling to obtain polyarylate fiber precursor; and

Unreeling the polyarylate fiber precursor, and performing heat treatment to obtain a polyarylate fine denier fiber;

wherein the temperature T1 of the spinning is more than or equal to Tm+20 ℃;

the cooling temperature T2 is less than or equal to Tm-180 ℃;

Wherein Tm represents the melting point of the polyarylate polymer.

Optionally, the polyarylate polymer comprises at least one of: polymer a, polymer B, copolymer C;

the polymer A is formed by copolymerization of aromatic hydroxycarboxylic acid, the polymer B is formed by copolymerization of aromatic dicarboxylic acid component and diol-containing component, and the copolymer C is formed by copolymerization of the polymer A and the polymer B;

the glycol-containing component comprises one of the following: an aromatic diol component and an aliphatic diol component.

Alternatively, the polyarylate polymer in the molten state satisfies: the melt viscosity MV of the polyarylate polymer in a molten state is 30 Pa.s to 60 Pa.s at a temperature of Tm+20deg.C and a shear rate of 1000 sec-1.

Optionally, spinning the polyarylate polymer in a molten state to obtain melt spinning, which specifically includes:

Spinning the polyarylate polymer in a molten state in a spinning assembly to obtain melt spinning;

wherein the spin pack assembly satisfies at least one of: the aperture of the spinning nozzle is not more than 0.10mm; the shearing speed T of the spinning nozzle is 10-3 sec < -1 > -10-6 sec < -1 >, and the ejection speed V1 of the spinning nozzle is 5-50 m/min.

Optionally, the cooling the melt spinning, and then coiling to obtain the polyarylate fiber precursor specifically includes:

Cooling the melt spinning at a position 30 cm-50 cm away from the spinning component, and coiling to obtain a polyarylate fiber precursor;

the coiling satisfies the following conditions: the value of winding speed V2 divided by ejection speed V1 >20.

Optionally, the spinning assembly includes:

A spinneret plate;

And the heater is used for heating the spinneret plate so as to ensure that the temperature of the melt spinning is kept constant before the temperature is 30cm to 50cm away from the spinneret plate of the spinning assembly.

Optionally, the heater is a heating jacket, and the heating jacket is located at the lower end of the spinneret plate, so that the melt spinning can pass through the heating jacket after being sprayed out of the spinneret plate.

Optionally, the unwinding of the polyarylate fiber precursor and the heat treatment are performed to obtain the polyarylate fine denier fiber, which specifically comprises: unreeling the polyarylate fiber precursor, and performing heat treatment in a vacuum environment or an inert gas atmosphere to obtain a polyarylate fine denier fiber;

Wherein the initial temperature of the heat treatment is Tm-100 ℃, and the final temperature of the heat treatment is Tm-30-Tm+20 ℃.

Optionally, the preparation of the polyarylate polymer in a molten state by using the polyarylate polymer as a raw material specifically includes:

and extruding the polyarylate polymer through a screw machine to obtain the polyarylate polymer in a molten state.

Optionally, before the polyarylate raw material is extruded by the screw machine, the method further comprises: and drying the polyarylate polymer for 6-8 hours in a vacuum environment at 160-180 ℃.

In a second aspect, the present invention also provides a polyarylate fine denier fiber produced by the method of producing the polyarylate fine denier fiber of the first aspect.

Optionally, the polyarylate fibers comprise at least one of the following properties: the single fiber linear density is less than 2.0D, and the strength is more than 30cN/dtex.

Compared with the prior art, the technical scheme provided by the invention has the following advantages:

The invention provides a polyarylate fine denier fiber and a preparation method thereof. The preparation process is simple, the production efficiency is high, and the method for stably producing the polyarylate fine denier fiber is provided, so that the raw material supply requirements of clothing and industrial applications are met.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.

FIG. 1 is a flow chart of a method for preparing a polyarylate fine denier fiber according to an embodiment of the present application;

Fig. 2 is a schematic structural diagram of a spinning device according to embodiment 1 of the present application;

FIG. 3 is a top view of the cooling device;

Wherein 1 is the subassembly cover, 2 is the spinneret, 3 is the heating cover, 4 is cooling device.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1,2, 3, 4,5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.

In the present application, unless otherwise indicated, the terms "comprise", "comprising", and the like mean "including but not limited to". Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.

Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.

spinning the polyarylate polymer in a molten state to obtain melt spinning;

wherein the temperature T1 of the spinning is more than or equal to Tm+20 ℃;

the cooling temperature T2 is less than or equal to Tm-180 ℃;

Wherein Tm represents the melting point of the polyarylate polymer.

In the above embodiment, the preparation method provided in the present invention requires strict control of the spinning temperature T1 and the temperature T2 at which melt spinning is rapidly cooled. First, when the temperature at which the module is spun is too high, the polyarylate raw material is thermally decomposed, and a column head or a yarn break is induced near the spinneret; if the spinning temperature is too low, the raw material cannot reach a certain melt viscosity, and the spinning cannot be smoothly performed.

The present invention aims to produce ultrafine polyarylate fine denier fibers, which have very fine fiber diameters, and have a rigid molecular long chain structure of the polyarylate polymer raw material, so that melt spinning is gradually cooled, which causes uneven fiber thickness and frequent filament breakage. Therefore, the melt spinning needs to be rapidly cooled, and the cooling temperature must be not more than Tm-180 ℃.

As an alternative embodiment, the polyarylate polymer comprises at least one of the following: polymer a, polymer B, copolymer C;

In the above embodiment, the addition of the aliphatic monomer is reduced among the monomers selected for the polyarylate polymer, and the high strength, high modulus and high heat resistance of the polymer can be ensured.

As an alternative embodiment, other performance improving ingredients are also included in the polyarylate polymer feedstock, including but not limited to pigments, heat stabilizers, light stabilizers, ultraviolet light absorbers, lubricants, optical brighteners, and the like.

As an alternative embodiment, the polyarylate polymer in the molten state satisfies: the melt viscosity MV of the polyarylate polymer in a molten state is 30 Pa.s to 60 Pa.s at a temperature of Tm+20deg.C and a shear rate of 1000 sec-1.

In the above embodiment, the following method was used for the measurement of melt viscosity: the temperature of the sample of the polyarylate polymer was raised to Tm +20 c using a capillary rheometer, and the viscosity of the polyarylate polymer at this time, i.e., melt viscosity MV, was measured by applying a shear rate of 1000sec-1 as the sample passed through the spinneret orifice of the spinneret.

When the melt viscosity MV is not in the range of 30 Pa.s to 60 Pa.s, it is revealed that the melt fluidity of the polymer is low, and a plurality of filament breaks are likely to occur at the outlet of the spinneret orifice, which is disadvantageous in that the spinning is successful.

As an alternative embodiment, the spinning the polyarylate polymer in a molten state to obtain melt spinning specifically includes:

As an alternative embodiment, the step of metering the polyarylate polymer in a molten state and filtering the same is further included before spinning the polyarylate polymer in a spinning assembly.

In the above embodiment, the metering of the polyarylate polymer feedstock is mainly used to control the amount of polyarylate feedstock passing through the spinneret, and the shear rate T is calculated according to the amount, where the calculation formula is t=4q/(pi r 3), Q is the flow rate of the polymer through the individual orifices in the spinneret, and r is the radius of the individual orifices. The filtering process is to filter out large particles which are not melted in the raw materials, so that the quality of the filament is affected; spinneret plates are used for the critical spinning process in the spinning process.

In the above embodiment, the reason for the reason that the aperture of the spinneret is not more than 0.10mm is mainly that the rigidity of the polyarylate polymer raw material is large and the post-stretching is hardly possible, so that the very fine fibers can be produced only by smaller spinneret orifices, and if the aperture is more than 0.10mm, the fiber orientation is low, the deterioration and the strength are low, and the very fine fibers cannot be formed at a high stretching ratio, and the breakage of the fibers easily occurs, but is too small and the spinneret is easily blocked, and is usually preferably 0.08mm to 0.1mm, which is disadvantageous for production.

As an alternative embodiment, the cooling and winding of the melt-spun yarn to obtain the polyarylate fiber precursor specifically includes:

The coiling satisfies the following conditions: when the winding speed V2 is divided by the ejection speed V1 by a value >20, the molecular orientation is insufficient, or the fine denier fiber is not obtained, or the intended high-strength, high-modulus ultrafine fiber is not obtained.

In melt spinning, the polyarylate is discharged from the spinneret holes, cooled and solidified, and then wound up, but in the production of ultrafine fibers, the discharge amount per hole is usually controlled to 0.5 g/min or less, so that the heat capacity of the discharged filaments is small. In the above embodiment, the melt-spun yarn is controlled to be cooled again at a position 30 to 50cm away from the spin pack, and the discharged melt-spun yarn can be prevented from being cooled in the vicinity of the spinneret, and the fiber spots tend to be large. If this tendency is severe, yarn breakage often occurs, and normal production is not possible. Therefore, in order to avoid the occurrence of the above-mentioned problems, the spinneret plate is subjected to strict temperature control, and the melt viscosity of the polymer melt is not uniform due to the temperature unevenness of the spinneret plate surface, so that the discharge amount between the spinneret holes is uniform, thereby achieving the purpose of reducing the sticking plate to the greatest extent.

As an alternative embodiment, the spin pack assembly includes:

A spinneret plate;

As an alternative embodiment, the heater is a heating jacket positioned at the lower end of the spinneret so that the melt-spun yarn can pass through the heating jacket after being ejected from the spinneret.

In the embodiment, the heating jacket is continuously heated from outside to inside, so that the temperature in the heating jacket is not lower than the temperature of the spinneret plate, the melt spinning is not cooled too early, and the occurrence of filament breakage and the like is reduced.

In order to rapidly cool the melt spinning at a distance of 30cm to 50cm from the spinneret, as an alternative embodiment, air cooling may be used or a cooling device may be used to cool the melt spinning.

In the above embodiment, the cooling device may be an annular cooling device, which is located at the bottom of the heating jacket, and the annular cooling device may cool air at a position 30 cm-50 cm away from the spinneret by water cooling or air blowing, so that the spinning is cooled rapidly at a position 30 cm-50 cm away from the spinneret.

As an alternative embodiment, the cooling device cools the melt spinning, specifically including: the cooling device blows air to cool the melt spinning from one direction or a plurality of directions;

Or the cooling device blows cooling air from the inner side of the melt spinning;

Or the cooling device is provided with cooling air around the melt spinning in an annular manner.

As an alternative embodiment, the unwinding of the polyarylate fiber precursor and the heat treatment to obtain the polyarylate fine denier fiber specifically comprises: unreeling the polyarylate fiber precursor, and performing heat treatment in a vacuum environment or an inert gas atmosphere to obtain a polyarylate fine denier fiber;

In the above embodiment, since the strength is 10 to 14g/d when the filament density of the polyarylate fiber precursor is 0.5 to 3.3 denier, it is remarkably undesirable, and thus it is required to improve the properties such as strength, modulus, etc. by heat treatment. In the case of using an inert gas as a medium, oil and a heating plate are used as heating sources, wherein the inert gas may use an inert gas having a dew point of-20 ℃ or lower, preferably-40 ℃ or lower, such as nitrogen; the heating may be directly performed by using a form of vacuum pumping or the like, and the heat treatment time may be several seconds to several tens of hours depending on the application and performance of the object.

As an alternative embodiment, a three-stage temperature heating process is typically employed during the heat treatment, such as heating at 150 to 180℃for 1 hour, 240 to 260℃for 4 hours, and 280 to 310℃for 10 hours.

As an alternative embodiment, the polyarylate polymer is prepared in a molten state from the polyarylate polymer, specifically comprising: and extruding the polyarylate raw material through a screw machine to obtain the polyarylate polymer in a molten state.

As an alternative embodiment, before the polyarylate raw material is extruded by the screw machine, the method further comprises: and drying the polyarylate polymer for 6-8 hours in a vacuum environment at 160-180 ℃.

In a second aspect, the present invention provides a polyarylate fine fiber produced by the method of producing a polyarylate fine fiber described in the first aspect.

The polyarylate fine denier fiber is realized based on the preparation method of the polyarylate fine denier fiber, and specific steps of the preparation method of the polyarylate fine denier fiber can refer to the above embodiment.

As an alternative embodiment, the polyarylate fiber comprises at least one of the following properties: the single fiber linear density is less than 2.0D, and the strength is more than 30cN/dtex.

The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to industry standards. If there is no corresponding industry standard, it is carried out according to the general international standard, the conventional conditions, or according to the conditions recommended by the manufacturer.

The polyarylate polymer feed in the following examples was selected from one of the two polymers set forth in the following table, the monomer compositions of which are shown in table 1:

TABLE 1 monomer composition of Polymer I and Polymer II

The molecular weight and the melting point of the polymer I and the polymer II are respectively tested, wherein the molecular weight of the polymer I and the molecular weight of the polymer II are respectively 25 ten thousand and 12 ten thousand;

The melting point test method comprises the following steps: first, a 10-20 mg sample of the polymer was taken in a differential scanning calorimeter (DSC apparatus), and after sealing in an aluminum pan, 50cc/min of nitrogen gas was introduced, and measurement was performed at a temperature rising rate of 10 ℃/min, and Tm is the peak of the endothermic peak. Depending on the type of polymer, there are cases where no distinct endothermic peak appears in the first measurement. At this time, the Tm can be measured by heating at a heating rate of 40℃per minute for about 4 minutes or so at a temperature higher than the temperature at which the insignificant endothermic peak appears and then cooling at 50℃per minute to 25℃and then measuring the Tm at the same heating rate of 10℃per minute.

The melting points Tm of Polymer I and Polymer II were determined to be 284℃and 320℃respectively, and this data will be used in all examples and comparative examples which follow.

The spinning device used in the following embodiments includes a component sleeve, a spinneret plate, a heating sleeve and a cooling device, as shown in fig. 2, the spinneret plate is located at the bottom of the component sleeve, the polyarylate polymer in a molten state is located in the component sleeve, and the molten spinning is ejected from a spinning nozzle of the spinneret plate at the bottom; the heating sleeve is positioned below the assembly sleeve and is in contact with the spinneret plate, and the sprayed melt spinning passes through the heating sleeve, so that the temperature of the melt spinning in the heating sleeve is ensured not to be reduced. The cooling device is positioned below the heating sleeve, and air below the heating sleeve is cooled by adopting a blowing or water cooling mode, so that the melt spinning is cooled rapidly after exiting the heating sleeve, and the polyarylate fiber precursor is obtained.

Example 1

The embodiment provides a polyarylate fine denier fiber, the preparation method of which comprises the following steps:

Taking a polyarylate polymer I as a raw material, wherein Tm=284 ℃; drying the raw materials in vacuum at 160 ℃ for 8 hours, extruding by a single screw extruder, controlling metering by a metering pump, filtering by a filter with the aperture of 5 mu m, and then spinning by a spinneret plate with the spinning aperture of 0.08mm and 40 holes to obtain melt spinning; melt viscosity mv=40 pa·s during spinning, the temperature of the spinning nozzle, i.e. the temperature T1 of spinning is 320 ℃ (T1 is not less than tm+20 ℃); the ejection velocity v1=20m/min, the shear velocity t=3.33X10-4sec-1.

Setting the temperature T2 for cooling the melt spinning at a position 30cm away from the spinning nozzle to be 100 ℃ (T2 is less than or equal to Tm-180 ℃), and coiling to obtain a polyarylate fiber precursor; wherein winding speed v2=800 m/min.

Unwinding and heat-treating the polyarylate fiber precursor, specifically, unwinding and winding the polyarylate fiber precursor on a stainless steel perforated bobbin covered by a buffer material formed by inorganic fibers, and heat-treating the polyarylate fiber precursor under vacuum: the polyarylate fine denier fiber is obtained after a duration of 1 hour at 150 ℃, 4 hours at 240 ℃ and 10 hours at 280 ℃.

The mechanical properties of the resulting polyarylate fine denier fibers are reported in table 2 for each of the experimental parameters in this example.

Example 2

Taking polyarylate polymer II as a raw material, wherein Tm=320 ℃; drying the raw materials in vacuum at 160 ℃ for 8 hours, extruding by a single screw extruder, controlling by a metering pump, filtering by a filter with the aperture of 5 mu m, and then spinning by a spinneret plate with the spinning aperture of 0.08mm and 50 holes to obtain melt spinning; melt viscosity mv=32 pa·s during spinning, the temperature of the spinning nozzle, i.e. the temperature T1 of spinning is 345 ℃ (T1 is not less than tm+20 ℃); the ejection speed was v1=20m/min, and the shear speed t=3.33X10-4sec-1.

Setting the temperature T2 for cooling the melt spinning at 140 ℃ (T2 is less than or equal to Tm-180 ℃) at a position 40cm away from the spinning nozzle, and coiling to obtain a polyarylate fiber precursor; wherein winding speed v2=800 m/min.

Unwinding and heat-treating the polyarylate fiber precursor, specifically, unwinding and winding the polyarylate fiber precursor on a stainless steel perforated bobbin covered by a buffer material formed by inorganic fibers, and heat-treating the polyarylate fiber precursor under vacuum: the polyarylate fine denier fiber is obtained by treating at 180 ℃ for 1 hour, at 260 ℃ for 4 hours, and at 310 ℃ for 10 hours.

Example 3

Taking a polyarylate polymer I as a raw material, wherein Tm=284 ℃; drying the raw materials in vacuum at 160 ℃ for 8 hours, extruding by a single screw extruder, controlling by a metering pump, filtering by a filter with the aperture of 5 mu m, and then spinning by a spinneret plate with the spinning aperture of 0.08mm and 40 holes to obtain melt spinning; melt viscosity mv=40 pa·s during spinning, the temperature of the spinning nozzle, i.e. the temperature T1 of spinning is 320 ℃ (T1 is not less than tm+20 ℃); the ejection velocity v1=20m/min, the shear velocity t=3.33X10-4sec-1.

Setting the temperature T2 for cooling the melt spinning at a position 50cm away from the spinning nozzle to be 100 ℃ (T2 is less than or equal to Tm-180 ℃), and coiling to obtain a polyarylate fiber precursor; wherein winding speed v2=1800 m/min.

Example 4

Taking polyarylate polymer II as a raw material, wherein Tm=320 ℃; drying the raw materials in vacuum at 160 ℃ for 8 hours, extruding by a single screw extruder, controlling by a metering pump, filtering by a filter with the aperture of 5 mu m, and then spinning by a spinneret plate with the spinning aperture of 0.08mm and 50 holes to obtain melt spinning; melt viscosity mv=32 pa·s during spinning, the temperature of the spinning nozzle, i.e. the temperature T1 of spinning is 345 ℃ (T1 is not less than tm+20 ℃); the ejection speed was v1=20 (m/min), and the shear speed t=3.33×10×4sec-1.

Setting the temperature of cooling the melt spinning at 100 ℃ (T2 is less than or equal to Tm-180 ℃) at a position 30cm away from the spinning nozzle, and coiling to obtain a polyarylate fiber precursor; wherein winding speed v2=1800 (m/min).

Comparative example 1

The comparative example provides a polyarylate fine denier fiber, the method of making comprising the steps of:

Taking a polyarylate polymer I as a raw material, wherein Tm=284 ℃; drying the raw materials in vacuum at 160 ℃ for 8 hours, extruding by a single screw extruder, controlling by a metering pump, filtering by a filter with the aperture of 5 mu m, and then spinning by a spinneret plate with the spinning aperture of 0.08mm and 40 holes to obtain melt spinning; melt viscosity mv=70 pa·s during spinning, the temperature of the spinning nozzle, i.e. the temperature T1 of spinning is 320 ℃ (T1 is not less than tm+20 ℃); the ejection velocity v1=20m/min, the shear velocity t=3.33X10-4sec-1.

In the preparation process, frequent yarn breakage and yarn floating are found, spinning cannot be performed stably, the winding speed is properly reduced to 300m/min, and the yarn can be effectively collected, but the obtained melt spinning has the linear density of: 160D/40f (single fiber 4D), does not meet the requirements for fine denier of the fiber of the present invention.

Comparative example 2

taking a polyarylate polymer I as a raw material, wherein Tm=284 ℃; drying the raw materials in vacuum at 160 ℃ for 8 hours, extruding by a single screw extruder, controlling by a metering pump, filtering by a filter with the aperture of 5 mu m, and then spinning by a spinneret plate with the spinning aperture of 0.12mm and 40 holes to obtain melt spinning; melt viscosity mv=40 pa·s during spinning, the temperature of the spinning nozzle, i.e. the spinning temperature is 320 ℃ (T1 is not less than tm+20 ℃); shear rate t=2.22×10×4sec-1, ejection rate v1=20 m/min.

Setting the temperature of cooling the melt spinning at 100 ℃ (T2 is less than or equal to Tm-180 ℃) at a position 30cm away from the spinning nozzle, and coiling to obtain a polyarylate fiber precursor; wherein winding speed v2=800 m/min.

After the spinning process is adopted, the phenomenon that the post head is dropped repeatedly at the spinning nozzle and cannot be stably spun is found, namely, after the shearing speed T=5.55X10-4 sec-1 and the spraying speed V1=50 m/min are adjusted, stable spinning can be found, but the linear density of the obtained melt spinning is as follows: 150D/40f (single fiber 3.75D) is not in accordance with the requirements of the present invention.

Comparative example 3

Setting the natural cooling temperature of the melt spinning at 100 ℃ (T2 is less than or equal to Tm-180 ℃), and coiling to obtain polyarylate fiber precursor; wherein winding speed v2=800 m/min.

After the spinning process is adopted for spinning, the phenomenon that the column head filaments and the floating filaments occur frequently is found, the tows shake obviously, and the filaments cannot be collected normally.

The specific parameters employed in examples 1 to 4 and comparative examples 1 to 3 and the properties of the resulting products were set as shown in Table 2 below:

table 2 experimental parameters and product properties in examples 1 to 4 and comparative examples 1 to 3

As is clear from the data recorded in the above table, the polyarylate fine denier fibers successfully prepared by the preparation method of the polyarylate fine denier fibers provided by the invention in examples 1 to 4 all meet the requirements that the linear density of single fibers is less than 2.0D and the strength is more than 30 cN/dtex. However, in comparative examples 1 to 3, the spinning could not be successfully performed due to the change of some parameters in the preparation process, such as the melt viscosity, the aperture of the spinneret and the cooling mode, and even if the spinning was successfully performed by adjusting the parameters, the obtained filaments had a fineness of much greater than 2.0D, which did not meet the requirements of the polyarylate fine denier fibers.

The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a polyarylate fine denier fiber, comprising the steps of:

spinning the polyarylate polymer in a molten state to obtain melt spinning;

wherein the temperature T1 of the spinning is more than or equal to Tm+20 ℃;

the cooling temperature T2 is less than or equal to Tm-180 ℃;

Wherein Tm represents the melting point of the polyarylate polymer.

2. The method of making a polyarylate fine denier fiber according to claim 1, wherein the polyarylate polymer comprises at least one of: polymer a, polymer B, copolymer C;

3. The method of producing a polyarylate fine fiber according to claim 1, wherein the polyarylate polymer in a molten state satisfies: the melt viscosity MV of the polyarylate polymer in a molten state is 30 Pa.s to 60 Pa.s at a temperature of Tm+20deg.C and a shear rate of 1000 sec-1.

4. The method for producing a polyarylate fine denier fiber according to claim 1, wherein said spinning said polyarylate polymer in a molten state, to obtain a melt-spun yarn, comprises:

5. The method for producing a polyarylate fine denier fiber according to claim 4, wherein said melt spinning is cooled and then wound to obtain a polyarylate fiber precursor, comprising:

6. The method of making a polyarylate fine denier fiber according to claim 4, wherein the spin pack assembly comprises:

A spinneret plate;

7. The method of producing a polyarylate fine denier fiber according to claim 6, wherein the heater is a heating jacket positioned at the lower end of the spinneret such that the melt spun yarn can pass through the heating jacket after being ejected from the spinneret.

8. The method for preparing the polyarylate fine denier fiber according to claim 1, wherein the unwinding of the polyarylate fiber precursor and the subsequent heat treatment are performed to obtain the polyarylate fine denier fiber, specifically comprising:

Unreeling the polyarylate fiber precursor, and then performing heat treatment in a vacuum environment or inert gas atmosphere to obtain a polyarylate fine denier fiber;

9. A polyarylate fine fiber characterized by being produced by the method of producing a polyarylate fine fiber according to any one of claims 1 to 8.

10. The polyarylate fine fiber of claim 9, wherein the polyarylate fine fiber comprises at least one of the following properties: the single fiber linear density is less than 2.0D, and the strength is more than 30cN/dtex.