JP2022178782A - Method for producing polymer alloy fibers - Google Patents

Abstract

To provide a method for producing polymer alloy fibers that allows functional components and functional particles to function efficiently by flowing at a high shear rate in a long channel to unevenly distribute island components scattered in a sea component of the polymer alloy fibers.SOLUTION: A method for producing a synthetic fiber comprises spinning after allowing polymers to flow at a shear rate of 50 to 3000 s-1 in a channel where a channel length relative to a channel diameter is 10 times or more.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for producing a polymer alloy fiber in which two or more different polymers are mixed.

Fibers made from thermoplastic polymers such as polyesters and polyamides are used in a wide range of industrial applications, from clothing to interiors and vehicle interiors, due to their excellent mechanical properties and dimensional stability. Various functional fibers have been developed along with the diversification of properties. For example, by thinning the fiber diameter, a soft texture is imparted, and by changing the cross section of the fiber from a normal round cross section to an irregular cross section, water absorption and quick drying may be imparted or the appearance may be changed. In addition, when the polymer itself constituting the fiber contains functional particles or copolymerizes other components to impart new functionality such as anti-see-through or UV protection, or two types In some cases, the above polymer is used as a conjugate fiber that constitutes the fiber.

This conjugate fiber can provide both functions that cannot be achieved with a single polymer, and can even give completely new functions, and has become a mainstream technology in the production method of functional fibers.

Composite fiber manufacturing methods include the polymer alloy method, in which multiple polymers are melted and mixed in a flow path, and the method in which multiple melted polymers are weighed and controlled in separate flow paths to obtain the desired fiber cross-section according to the purpose. There are composite spinning methods to form, and among them, the polymer alloy method makes it possible to manufacture functional fibers with general-purpose spinning equipment, and it is easy to adopt as a development aimed at improving the functionality of textile products, and is being widely deployed. there is

In the polymer alloy method, there are various methods such as dry blending two or more resins and melting them in a mixed state, or kneading the combined resins by a melt extruder having a kneading function in advance. In these methods, by appropriately adjusting the mixing conditions and combining two or more types of polymers, it is possible to produce a polymer alloy fiber in which the other polymer is finely dispersed as an island component in a sea component serving as a matrix. It becomes possible.

In the polymer alloy fiber, by utilizing a compatibilizer or the like, which is an intermediate component of the polymer to be combined, the island component is evenly and finely dispersed in the sea component, so that the defects and functions of the polymer of the sea component can be improved. Patent document 1 or patent document 2 discloses the technology.

Patent Document 1 discloses a technique of mixing polylactic acid and polypropylene, which are a combination of polymers with relatively low affinity, by using a specific compatibilizer to obtain a composite fiber in which the polypropylene is the sea and the polylactic acid is the island. It is According to Patent Document 1, by combining the properties of each polymer, it is possible to produce a polymer alloy fiber that achieves both heat resistance and dyeability, which has not been achieved in the past.

Further, in Patent Document 2, a polyolefin obtained by copolymerizing an acid anhydride group-containing unsaturated compound with a polyamide is melt-mixed, and the polyolefin is finely dispersed in the matrix of the polyamide. It suppresses dimensional changes due to water absorption and moisture absorption, and as an additional effect, it is said that it is possible to manufacture polymer alloy fibers with vivid dyeability and unique texture.

JP 2010-15072 A (Claims) Japanese Patent Laid-Open No. 7-70822 (Claims)

Patent document 1 aims at improving heat resistance by finely dispersing polylactic acid having high heat resistance in polypropylene, which is a sea component. However, when the bulk properties of the polymer alloy fiber are evaluated, the effect of improving the heat resistance is certainly obtained, but the outermost layer of the fiber has a portion where the polypropylene with low heat resistance is exposed. Therefore, for example, when a force is applied in the compression direction while being heated, such as iron heat resistance, or when it is heated as a yarn bundle, the polypropylene on the surface of the fiber will melt, and the fiber will collapse or melt between adjacent fibers. It is hard to say that practical heat resistance can be imparted, such as causing wear.

Patent document 2 uses polyamide as the sea component and polyolefin as the island component, and polyolefin with high hydrophobicity is dispersed and mixed in polyamide with high water absorbency and hygroscopicity, resulting in water absorption, which is a problem of polyamide single fibers. It is expected to suppress dimensional change due to swelling. However, in Patent Document 2, as in Patent Document 1, the outermost layer of the fiber that substantially contacts moisture has a portion where polyamide alone exists, and moisture is absorbed from there. In some cases, the effect of suppressing dimensional change to the extent that was achieved could not be obtained.

Patent document 1 and patent document 2 relate to a polymer alloy fiber obtained by melt-blending two types of polymers with different properties, and by utilizing a compatibilizer, etc., the island component is finely dispersed in the sea component serving as the matrix. The technical idea is to create a state in which the sea component polymer alone does not exhibit functions such as heat resistance and hydrophobicity.

However, in Patent Literature 1 and Patent Literature 2, the island components are basically uniformly dispersed, and furthermore, they cannot be arbitrarily arranged in the cross section of the fiber. may not be available. Therefore, in order to develop the target properties, it may be necessary to excessively increase the mixing ratio of the island component. In particular, when the target property is a change in the properties of the outermost layer of the fiber, it becomes necessary to increase the abundance ratio of the island component in the outermost layer, naturally resulting in an excessive increase in the mixing ratio of the island component. . In this case, the functional polymer is certainly arranged on the surface layer of the fiber, but the excessive island component arranged in the inner layer does not exhibit its effect, and the fiber as a whole is an unnecessary island component. There will be many ingredients. In this case, many unnecessary island components exist in the inner layer. In some cases, the intended effect of adopting the alloy method was not achieved.

In addition, when it is necessary to increase the mixing ratio of the island component more than necessary, it is necessary to control the mixing conditions in a complicated manner in order to suppress fluctuations in the mixing ratio over time. Polymer alloys, which exist evenly, often have complex rheological characteristics in which the fluidity of two types of polymers exists, and unstable ejection behavior such as unstable behavior when ejected from a spinneret. In some cases, the spinnability was greatly reduced.

Therefore, there is a need for a production method that can control the state of dispersion of island components in polymer alloy fibers, and a production method for polymer alloy fibers that can control the dispersion form and arrangement of the island components.

The object of the present invention is achieved by the following means. i.e.
(1) A method for producing a polymer alloy fiber, characterized in that a plurality of polymers are flowed at a shear rate of 50 to 3000 s ⁻¹ in a channel having a channel length of 10 times or more relative to the channel diameter, and then spun. .
(2) The method for producing a polymer alloy fiber according to (1), wherein the channel length is 30 times or more the channel diameter.
(3) The method for producing a polymer alloy fiber according to (1) or (2), wherein the shear rate of the plurality of polymers in the channel is 50 to 1000 s ^-1 .
is.

In the production method of the present invention, in a polymer alloy fiber in which a plurality of polymers are melted and mixed, by unevenly distributing the island components scattered in the sea component, the functional component and functional particles are made to function efficiently. It becomes possible to provide a method for manufacturing fibers.

FIG. 1 is a diagram relating to a long flow channel used in the present invention, (a) is a schematic diagram of a spinneret in which the long flow channel is installed, and (b) is a schematic diagram of the long flow channel installed in the spinneret. Schematic diagram, (c) is a schematic diagram of a cross section of a long channel. FIG. 2 is a schematic diagram of a cross-sectional structure in which there is an island component with induced localization in the polymer alloy fiber produced according to the present invention;

Hereinafter, the present invention will be described in detail together with preferred embodiments.

In the production method of the present invention, in the melt spinning process, it is necessary to flow a plurality of polymers at a shear rate of 50 to 3000 s ⁻¹ in a channel having a channel length that is 10 times or more the channel diameter.

Controlling the pressure loss in the flow field is important for inducing the peculiar phenomenon in which the island components of the melt-mixed polymer are unevenly distributed near the fiber surface, which is a feature of the present invention. That is, when a plurality of polymers having different viscosities are mixed and flowed, a phenomenon is induced that minimizes the gradient of pressure loss in the flow channel in order to stabilize the flow field. Therefore, if the mixed polymers have different melt viscosities and fluidities, components with good fluidity, for example, low-viscosity components will be extruded near the wall surface of the channel. In this case, as the gradient of the pressure loss in the channel becomes more pronounced, the phenomenon that the low-viscosity component is pushed out to the vicinity of the wall surface is strongly expressed, and in the long channel, etc., the uneven distribution of the low-viscosity component in the polymer alloy is induced. It is done.

The technical idea of the present invention is based on the discovery of a peculiar phenomenon induced when a polymer alloy in which two or more types of polymers are mixed flows in a special flow field. flow path becomes important. The term "channel" as used herein refers to a passage through which the molten polymer flows, and a special flow field can be controlled by the channel diameter and channel length.

The channel diameter of the present invention means the diameter of a cross section of a channel for polymer flow when the channel is viewed perpendicularly from the flow direction of the polymer. Refers to the circle equivalent diameter calculated by converting the area obtained from Further, the channel length in the present invention means the length of a line connecting the center of the cross section at the channel inlet to the center of the cross section at the channel outlet along the polymer flow direction.

In order to create a special flow field necessary for the achievement of the present invention, the length of the channel must be at least 10 times the diameter of the channel, which is the first requirement of the present invention.

The channel used in the present invention having a channel length of 10 times or more with respect to the channel diameter is a channel having a sufficiently long ratio of the channel length to the channel diameter as compared with the channel used in a normal melt spinning process. means In order to achieve the present invention, this special flow path is installed at any point where the mixed polymer is melted by a heater or the like, passes through each melt-spinning member, and is then discharged in the form of fibers from the spinneret discharge holes. It is possible to make specifications suitable for the melt spinning apparatus, piping, spinning pack, and the like to be used. However, when it is necessary to make the characteristic fiber cross section in which one of the polymers is unevenly distributed, which is the object of the present invention, more conspicuously, the polymer flow is induced by a special flow field, and then the ejection hole is discharged immediately after the uneven distribution phenomenon is induced. It is preferable that the fiber is discharged from the fiber in the form of fibers, and that the fiber is preferably perforated in any member of the melt spinning pack including the spinneret.

In this case, when a combination of polymers with low affinity or a combination of polymers with significantly different melting points are fiberized at the same melting temperature, the effect of suppressing deterioration of the polymer and excessive recombination of unevenly distributed components is also obtained. For this reason, it can be cited as a preferred embodiment of the present invention, and furthermore, from the viewpoint of controlling a special composite flow in which the single components are unevenly distributed, a flow path is bored in the spinneret for implementing the present invention. It is more preferable to set By piercing the flow path used for carrying out the present invention in the spinneret, the effects of the present invention described above can be effectively applied to the collected fibers. Since it becomes possible to change variously controlled fiber cross-sections, it is also suitable from an industrial point of view, as it eliminates the need to secure unnecessary members and modify a complicated spinning device.

In the present invention, it is necessary to flow under specific flow conditions in the above-described special flow path, and by meeting these two requirements, a unique phenomenon of uneven distribution of the mixed polymer fragment components is induced. becomes possible.

The specific flow conditions are based on the principle of moving the mixed polymer piece components in the cross-sectional direction using shear stress, and it is important to set the shear rate in the flow within a specific range. That is, it is necessary to control the polymer flow in the channel so that the shear rate is 50 to 3000 s ⁻¹ , which is the second requirement of the present invention.

The shear rate referred to in the present invention is uniquely determined based on the following formula from the melt density of the polymer to be flowed, the discharge rate and the diameter of the flow path. can be controlled by setting
Shear rate = Discharge rate / {π x melt density x (channel diameter) ² } (1)
The discharge rate referred to here means the mass of the weighed molten polymer that flows in the flow path in one minute, and the melt density is a characteristic value according to the polymer composition to be used, and a known value can be used. can. In a polymer composition in which different polymers are mixed, it is possible to calculate by applying the melt density estimated from the mixing ratio using the melt density unique to the polymer based on formula (1). For example, in the case of a polymer in which polyethylene terephthalate (melt density 1.18 g/cm ³ ) and nylon 6 (melt density 0.74 g/cm ³ ) are mixed at 70:30, 1.18 × 0.7 + 0.74 ×0.3=1.42 g/cm ³ and the melt density of the mixed polymer are calculated, and the shear rate is calculated based on the formula (1).

In carrying out the present invention, it is important that the specification of the flow path, which is important in the practice of the present invention, is three-dimensionally designed so that the flow path length with respect to the flow path diameter satisfies the above-mentioned range. should be installed so as to match the equipment and components to be installed.

In order to induce this peculiar phenomenon in the flow field when a simple long channel is used, it is necessary to flow the polymer at a low speed through a dedicated long channel. In particular, in the melt-molding process, deterioration of the resin due to hydrolysis, oxidative decomposition, or the like may become a problem as it flows through the channel. In the case of a polymer in which two or more different polymers are mixed in a molten state, the decomposition product of one polymer may accelerate the deterioration of the other polymer, which affects the process passability of fiber molding and the final result. In some cases, it was difficult to apply the method to the actual molding process, such as when the desired effect could not be obtained due to the fiber characteristics.

In particular, among melt molding processes, the above effects are often noticeable in melt spinning processes, etc., where the polymer flow rate is low and the residence time in the molten state is long. is often difficult. To solve these problems of the prior art, the present inventors have made intensive studies and found that, in the melt spinning process, one component of a plurality of melt-mixed polymers is unevenly distributed without unnecessarily complicating equipment and the like. He discovered a peculiar phenomenon that was found in the melt spinning process, and succeeded in applying it to the melt spinning process.

The flow path necessary for the implementation of the present invention is to determine the specifications in advance by designing the member so that the flow path length with respect to the flow path diameter satisfies the above range. Actual measurement of specifications is possible by the following method. In other words, in the evaluation of flow path specifications, indirect and non-destructive measurement can be applied to the measurement of various members. is preferred in the present invention. As a specific example, a three-dimensional CT image is captured using XDimensus300 manufactured by Shimadzu Corporation, converted to a grayscale image using WinROOF manufactured by Mitani Corporation, which is image analysis software, and binarized by adjusting the threshold value. By performing the processing, the channel cross section is extracted and the area and circumference are measured.

In the production method of the present invention, the channel length should be appropriately set according to the intended use in the range of 10 times or more the channel diameter, but it increases the pressure loss and makes the uneven distribution more noticeable. , it is preferable that the channel length is 30 times or more the channel diameter. However, if the channel length is too long, it may not be applicable to the spinning process, or the polymer with low heat resistance cannot be used because the residence time becomes unnecessarily long. More preferably, it is 30 times or more and 100 times or less. In addition, in the production method of the present invention, it should be appropriately set to flow in the channel at a shear rate in the range of 50 to 3000 s ^-1 , but in a high shear rate range around 3000 s ^-1 , aggregated and unevenly distributed It is preferable to set the shear rate to 50 to 1000 s ⁻¹ because the layer may be cut and uneven distribution may be suppressed. In order to reduce the shear rate, in the case of the same polymer and the same spinning temperature, a method of decreasing the discharge rate and increasing the flow path diameter according to formula (1) can be mentioned. It is preferable to reduce the diameter of the flow path, because the length of the flow path may cause thermal deterioration.

The polymer alloy referred to in the present invention means a blend of a plurality of polymers separated into a sea component and an island component. For example, it can be obtained by kneading with a melt kneading extruder such as an extruder, and a polymer alloy fiber can be obtained by a known spinning method such as melt spinning. The term "island component" as used herein means an island component among different components separated into islands-in-the-sea by blending. Further, the islands-in-the-sea shape means that the islands are divided into a plurality of sea areas.

The polymer alloy fiber produced by the present invention needs to be flowed under specific flow conditions in the special flow path as described above, and by meeting these requirements, the mixed polymer fragment components are unevenly distributed. It becomes possible to induce a peculiar phenomenon. Here, uneven distribution refers to the case where the island component diameter CV% scattered in the cross section of the fiber is 20% or more. The island component diameter CV% referred to here is obtained by the method described later. If this value is large, there is a distribution in the size of the island components existing in the same fiber cross section, and island components with a large size are found locally. means to exist. This value is less than 20% for a general polymer alloy fiber, but when uneven distribution of island components, which is the intended effect of the present invention, is induced, the size distribution of the island components is generated, and the present invention. A guideline for the effect of is that the island component CV% is 20% or more. If the island component diameter CV% is 20% or more, it means that uneven distribution is induced, which is within the preferred range of the present invention. Proceeding with this idea, it is preferable that the size distribution of the island component be large, and from the viewpoint of more effectively exhibiting the desired function, it is more preferable that the island component diameter CV% is 30% or more. range.

The island component diameter CV% in the present invention is calculated by the following formula.
Island component diameter CV%=(standard deviation of diameter/average diameter)×100 (2)
The standard deviation and average diameter referred to here are obtained as follows. That is, a cross section perpendicular to the fiber axis of a single polymer alloy fiber is photographed with a transmission electron microscope (TEM) or a scanning electron microscope (SEM) at a magnification that allows observation of 150 or more island component polymers. At this time, if necessary, metal dyeing can be applied to clarify the contrast between the sea component and the island component. From the two-dimensionally photographed image, an image processing software (eg, WinROOF manufactured by Mitani Corporation) is used to measure the diameter of island components randomly extracted from the same image. Here, the island component polymer appearing in the cross section of the fiber is not necessarily a perfect circle. Further, these values are measured in units of nm to the first decimal place and rounded off to the nearest decimal place. The average diameter is obtained by measuring the diameter of each island component and obtaining a simple numerical average value thereof, and the standard deviation of the diameter is calculated from the diameter of each island component and the average diameter.

The plurality of polymers used in the production method of the present invention is appropriately selected from two or more types of polymers depending on the application, but the desired functional ingredients and functional ingredients can be effectively expressed. From the viewpoint of controlling the stability of the cross-sectional shape, etc., it is preferable to use two types of polymers. Specific combinations include polyester-based polybutylene terephthalate/polyethylene terephthalate, polytrimethylene terephthalate/polyethylene terephthalate, thermoplastic polyurethane/polyethylene terephthalate, polyester-based elastomer/polyethylene terephthalate, polyester-based elastomer/polybutylene terephthalate, Nylon 6-nylon 66 copolymer/nylon 6 or 610 as polyamide system, polyethylene glycol (PEG) copolymerized nylon 6/nylon 6 or 610, thermoplastic polyurethane/nylon 6 or 610, ethylene-propylene rubber fine dispersion as polyolefin system Polypropylene/polypropylene, propylene-α-olefin copolymer/polypropylene, and the like can be mentioned. Combinations with low affinity include polyethylene terephthalate/nylon 6, polyethylene terephthalate/nylon 66, polyethylene terephthalate/polypropylene, polyethylene terephthalate/polyethylene, nylon 6/polypropylene, nylon 6/polyethylene, nylon 66/polypropylene, nylon 66/polyethylene, and the like. is mentioned. In addition, various additives such as inorganic substances such as titanium oxide, silica, and barium oxide, carbon black, colorants such as dyes and pigments, flame retardants, fluorescent brighteners, antioxidants, and ultraviolet absorbers are included in the polymer. You can stay.

Considering that the gradient of the pressure loss in the flow channel is made remarkable between these two types of polymers, it is preferable to use a polymer combination in which the ratio of the maximum viscosity to the minimum viscosity in the mixed polymer is 1.5 times or more. Within this range, the low-viscosity component efficiently migrates to the wall surface, and uneven distribution of the island component, which is the object of the present invention, is induced without any problem. Also, if the viscosity ratio is 1.5 times or more, uneven distribution is induced, but in order to make the uneven distribution noticeable and further increase the size distribution of the island component, it is more preferably 5.0 times or more. The viscosity ratio referred to here is the ratio of the melt viscosities of each polymer measured at the same temperature and shear rate (1216 s ⁻¹ ) using a capilograph manufactured by Toyo Seiki Co., Ltd., and calculated.

In the manufacturing method of the present invention, the polymer can be ejected in a range of 0.1 g/min/hole to 20.0 g/min/hole per ejection hole, which can be melted and ejected while maintaining stability. At this time, it is preferable to take into consideration the pressure loss in the ejection hole that can ensure the stability of ejection. The pressure loss referred to here is preferably 0.1 MPa to 40 MPa as a guideline, and is preferably determined from the range of the discharge rate based on the relationship between the melt viscosity of the polymer, the diameter of the discharge hole, and the length of the discharge hole.

The ratio of the high-viscosity component polymer and the low-viscosity component polymer when spinning the composite fiber used in the production method of the present invention can be selected in the range of 5/95 to 95/5 in weight ratio based on the discharge amount. . Within this range, uneven distribution is induced and stable production can be achieved. , the polymer ratio is preferably 5/95 to 70/30.

The polymer flow melted and discharged from the discharge hole is cooled and solidified, converged by applying an oil or the like, and taken up by a roller having a specified peripheral speed. In the present invention, from the viewpoint of stable production, the take-up speed of the rollers is preferably about 500 to 6000 m/min, which can be changed depending on the physical properties of the polymer and the purpose of use of the fiber. During stretching, it is preferable to appropriately set the preheating temperature with reference to the temperature at which the polymer can be softened, such as the glass transition temperature of the polymer. As for the upper limit of the preheating temperature, it is preferable to set the temperature at which the spontaneous elongation of the fibers during the preheating process does not cause disturbance of the yarn path. For example, in the case of PET having a glass transition temperature of around 70.degree. In the case of a polymer that does not show glass transition, the dynamic viscoelasticity measurement (tan δ) of the composite fiber is performed, and a temperature equal to or higher than the peak temperature on the high temperature side of the obtained tan δ is selected as the preheating temperature. Here, from the viewpoint of increasing the draw ratio and improving the mechanical properties, it is also a suitable means to apply this drawing step in multiple stages. As for the drawing, the spun conjugate fiber may be drawn after being once wound up, or may be drawn after spinning without being once wound up. False twisting may be added in addition to drawing.

The method of false twisting is not particularly limited as long as it is a method generally used for polyester, etc., but in consideration of productivity, a friction false twisting machine using a disc or belt is used for processing. is preferred.

As described above, the method for producing the polymer alloy fiber of the present invention has been described, but it goes without saying that it can also be produced by the meltblowing method and the spunbond method, and furthermore, it can be produced by a solution spinning method such as a wet and dry-wet method. It is also possible to

The ultrafine fibers of the present invention will be specifically described below with reference to examples.

Examples and comparative examples were evaluated as follows.

A. Flow path length to flow path diameter ratio A three-dimensional CT image was captured using XDimensus300 manufactured by Shimadzu Corporation, converted to a grayscale image using WinROOF manufactured by Mitani Shoji, which is an image analysis software, and the threshold value was adjusted. After performing binarization processing, if the channel diameter is calculated by extracting the channel cross section and measuring the area and perimeter, if the channel length is calculated from the center of the cross section at the channel inlet , and the length of a line connecting the center of the cross section at the channel outlet along the direction of polymer flow was measured. Further, the ratio of the channel length to the channel diameter was obtained by rounding off the value obtained by dividing the channel length by the channel diameter.

B. Shear Rate The shear rate (s ⁻¹ ) of the polymer flowing through the channel in each example and comparative example was calculated using formula (1).

C. Polymer Melt Viscosity and Viscosity Ratio A chip-shaped polymer was made to have a moisture content of 200 ppm or less by a vacuum dryer, and the melt viscosity was measured by Toyo Seiki Capilograph 1B. Further, the value obtained by dividing the melt viscosity of the high-viscosity component polymer by the melt viscosity of the low-viscosity component polymer was rounded off to two decimal places to obtain the viscosity ratio. The measurement temperature is the same as the spinning temperature, and melt viscosity at a shear rate of 1216 s ⁻¹ is described in Examples and Comparative Examples. In addition, the measurement was performed in a nitrogen atmosphere with 5 minutes from the time when the sample was put into the heating furnace until the time when the measurement was started.

D. Fineness The fineness was calculated by measuring the weight of 100 m of the polymer alloy fiber and multiplying it by 100. This was repeated 10 times, and the fineness was obtained by rounding off the simple average value to the second decimal place.

E. Evaluation of uneven distribution With respect to the fiber cross section of each example and comparative example, the uneven distribution was evaluated in the following three stages from the value of each island component diameter CV% calculated using the formula (2).
Very good S: 40% or more good A: 20% or more poor B: Less than 20%.

[Example 1]
Polyethylene terephthalate (PET, melt viscosity: 120 Pa s) as the high-viscosity component polymer, and 8.0 mol% of 5-sodium sulfoisophthalic acid and polyethylene glycol as the low-viscosity component polymer so that the viscosity ratio is 1.5. Two polymers of polyethylene terephthalate (SSIA-PEG copolymerized PET, melt viscosity: 80 Pa·s) were prepared by copolymerizing 9 wt% of After adjusting the weight ratio of the high-viscosity component polymer and the low-viscosity component polymer to 70/30 and melt-mixing them at 290°C using an extruder, the spinning temperature was set to 290°C and weighing was performed using a pump. A long channel having a channel length 40 times as long as the channel diameter shown was made to flow at a shear rate of 50 s ⁻¹ and discharged from the discharge hole at 0.70 g/min/hole.

After cooling and solidifying the polymer flow discharged from the discharge hole, an oil agent is applied, wound at a spinning speed of 1000 m / min, and drawn 3.0 times between rollers heated to 90 ° C. and 130 ° C. to spin and draw. A polymer alloy fiber of 56 dtex-24 filament (single fiber fineness 2.3 dtex) was obtained through the process.

The cross section of the obtained polymer alloy fiber is a cross section in which the high viscosity component is the sea component and the low viscosity component is the island component. Large island components were present, and uneven distribution of the island components, which is the effect of the present invention, was induced very well. Table 1 shows the results.

[Examples 2 and 3]
A polymer alloy fiber of 56 dtex-24 filaments was obtained in the same manner as in Example 1, except that the channel was designed to flow in the long channel at a shear rate of 500 s ^-1 (Example 2) and 1000 s ^-1 (Example 3). rice field.

By making the shear rate in the channel higher than that in Example 1, the pressure loss in the channel increased and the island components were more likely to aggregate, so the island component diameter CV% of the resulting polymer alloy fiber was 55.2. % (Example 2) and 72.8% (Example 3). Table 1 shows the results.

[Example 4]
A 56 dtex-24 filament polymer alloy fiber was obtained in the same manner as in Example 1, except that the flow path was designed to flow in the long flow path at a shear rate of 3000 s ⁻¹ .

By making the shear rate in the channel higher than in Example 1, the pressure loss in the channel increased, but the island component was cut by the high shear, so the island component diameter CV% of the obtained polymer alloy fiber was 34.5%, and uneven distribution of island components could be confirmed.

Table 1 shows the results.

[Example 5]
A 56 dtex-24 filament polymer alloy fiber was obtained in the same manner as in Example 1, except that the polymer was allowed to flow in a long channel having a channel length ten times the channel diameter.

Since the channel was shorter than that of Example 1, the pressure loss in the channel was low, and the obtained polymer alloy fiber had an island component diameter CV% value of 25.4%. Table 1 shows the results.

[Examples 6 and 7]
56 dtex-24 filament polymer alloy fiber in accordance with Example 1 except that the polymer is made to flow in a long channel with a channel length that is 70 times (Example 6) and 100 times (Example 7) the channel diameter. got

By making the flow path longer than in Example 1, the pressure loss in the flow path increased and the island components easily aggregated, so the island component diameter CV% of the obtained polymer alloy fiber was 57.1% Example 6) and 85.1% (Example 7). Table 1 shows the results.

[Example 8]
High molecular weight polyethylene terephthalate (high molecular weight PET, melt viscosity: 650 Pa s) as the high viscosity component polymer and PET (melt viscosity: 120 Pa s) as the low viscosity component polymer were used so that the viscosity ratio was 5.4. A 56 dtex-24 filament polymer alloy fiber was obtained in accordance with Example 1 except for the preparation.

By making the viscosity ratio higher than in Example 1, the pressure loss in the flow path increased and the island components tended to aggregate, so the island component diameter CV% of the resulting polymer alloy fiber was 52.0%. . Table 1 shows the results.

[Example 9]
A 56 dtex-24 filament polymer was prepared in accordance with Example 1, except that high-molecular-weight PET was prepared as the high-viscosity component polymer and SSIA-PEG copolymerization PET was prepared as the low-viscosity component polymer so that the viscosity ratio was 8.1. An alloy fiber was obtained.

By making the viscosity ratio higher than in Examples 1 and 8, the pressure loss in the flow path increased and the island components were more likely to aggregate, so the island component diameter CV% of the resulting polymer alloy fiber was 87.2. %, and uneven distribution was better than in Examples 1 and 8. Table 1 shows the results.

[Comparative Example 1]
A polymer alloy fiber of 56 dtex-24 filaments was obtained in the same manner as in Example 1, except that the flow path was designed to flow in the long flow path at a shear rate of 25 s ⁻¹ .

By making the shear rate in the channel lower than that in Example 1, the pressure loss in the channel was reduced, and the island component was relatively homogeneously and finely dispersed. The resulting polymer alloy fiber had an island component diameter CV% of 12.6%, which is a cross-sectional shape that cannot be said to have induced uneven distribution of island components, which is a feature of the present invention. Table 2 shows the results.

[Comparative Example 2]
A 56 dtex-24 filament polymer alloy fiber was obtained in the same manner as in Example 1, except that the flow path was designed to flow in the long flow path at a shear rate of 4000 s ⁻¹ .

Since the shear rate in the channel was too high compared to Example 1, the pressure loss in the channel increased, while the island component was cut by the high shear, and the resulting polymer alloy fiber had an island component diameter CV% of 18. 0.3%, and the island component was relatively uniformly and finely dispersed in the cross section of the fiber. Table 2 shows the results.

[Comparative Example 3]
A 56 dtex-24 filament polymer alloy fiber was obtained in the same manner as in Example 1, except that the polymer was allowed to flow in a long channel having a channel length five times the channel diameter.

By making the shear rate in the channel lower than that in Example 1, the pressure loss in the channel decreased and the island components were evenly and finely dispersed. At 14.8%, the island component characteristic of the present invention was not induced much. Table 2 shows the results.

[Comparative Example 4]
PET (melt viscosity: 120 Pa s) as a high-viscosity component polymer and isophthalic as a low-viscosity component polymer so that the channel length is 9 times the channel diameter and the viscosity ratio is 1.2 A 56 dtex-24 filament polymer alloy fiber was obtained in the same manner as in Example 1, except that polyethylene terephthalate (IPA copolymerized PET, melt viscosity: 100 Pa·s) was prepared by copolymerizing 7 mol % of acid.

By making the viscosity ratio lower than in Example 1, the pressure loss in the flow channel was reduced, and the island components were evenly and finely dispersed. However, the island component, which is a feature of the present invention, was not significantly induced. Table 2 shows the results.

1: Metering plate 2: Metering hole 3: Long channel plate 4: Long channel 5: Discharge plate 6: Discharge hole 7: Channel length 8: Channel cross section 9: Channel diameter A: Evenly finely dispersed Example of island component B: Example of island component in which uneven distribution is induced

Claims (3)

A method for producing a synthetic fiber, characterized in that a plurality of polymers are caused to flow at a shear rate of 50 to 3000 s ⁻¹ in a channel having a channel length that is 10 times or more the channel diameter, and then spun. 2. The method for producing a synthetic fiber according to claim 1, wherein the channel length is 30 times or more the channel diameter. 3. The method for producing synthetic fibers according to claim 1, wherein the shear rate of the plurality of polymers in the channel is 50-1000 s ^-1 .

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