Patent Application
20250084564
The present disclosure relates to a method of manufacturing a high-strength sheath-core type synthetic fiber, and a high-strength sheath-core type synthetic fiber manufactured thereby, and more particularly, a low-cost and highly efficient method of manufacturing high-strength synthetic fiber and a high-strength synthetic fiber manufactured thereby, which may, in a bicomponent melt spinning process, improve or suppress structural development of each polymer component in the fiber and may also enable changes in molecular chain entanglement and structural control using differences in thermal conductivity, specific heat, and elongation viscosity between two or more polymers in a bicomponent fiber, and may also improve productivity by increasing a take-up velocity and a draw ratio by enabling more uniform structural development in a cross-sectional direction of fiber.
Among commercialized polyethylene terephthalate (PET) products, a maximum strength thereof may be about 1.1 GPa, and maximum obtainable strength as compared to theoretical strength may be 3 to 4%, which is a ⅓ level, of about 2.9 GPa of another high-strength fiber, extreme performance para-aramid (Kevlar) fiber. Accordingly, there may be limitations in application of the fiber as industrial fiber materials requiring extreme performance, other than some fiber materials for general clothing, household use, or industrial use such as tire cords. As mentioned above, PET and nylon-based fibers, which are non-liquid crystal thermoplastic fibers, may have strength lower than those of PBO (Zylon) and para-aramid (Kevlar)-based fibers, which are liquid crystal polymer (LCP) fibers, and actual strength thereof may not be increased dramatically as compared to theoretical examples because there may be a difference in structure development behavior when processing from resin to fiber.
Since liquid crystal polymer (LCP) forms a liquid crystalline structure in a solution state, when appropriate shear stress is applied, LCP may form a fiber structure having relatively high orientation and crystallinity through a high shear-thinning effect, such that LCP may be manufactured as a high-strength high-performance fiber. Meanwhile, PET and nylon-based non-liquid crystal thermoplastic polymer may have a complex structure in which polymer chains are entangled as an amorphous random coil phase in a melted state, such that, even when a high shear stress is applied in a spinning nozzle and a high elongational stress is applied in a spinning line, due to the structure entangled in a random coil phase, it may be relatively difficult in manufacturing high-strength fiber having high orientation and crystallinity.
Despite the structural disadvantages of non-liquid crystal thermoplastic polymers, if relatively more improved high-strength PET fibers are able to be developed as compared to their conventional fibers, the application market and effects thereof would be significantly increased, and thus, over the past several decades, various studies have been conducted in the fiber industry to maximize physical properties and to raise performance of PET fiber. For example, as research into developing a high-strength PET fiber, researches on PET resin of ultra-high molecular weight and maximizing molecular orientation by applying a coagulation bath technique to melt spinning process have been reported. However, commercialization of a high-strength PET fiber based on these studies has not been embarked upon due to limitations in work environment and productivity as compared to the effect of improving physical properties.
Meanwhile, the bicomponent melt spinning method may be a spinning method in which two or more thermoplastic polymer resins are melted using different extruders, then supplied to a spinning nozzle through a gear pump, and spinning is performed. By appropriate design of the spinning nozzle, bicomponent fibers with cross-sections such as sheath-core, side-by-side, and islands in the sea can be manufactured, and the method has been widely used to manufacture high functional fibers for clothing over the past several decades. In relation to using the bicomponent melt spinning method, in the case in which a technique which may improve mechanical properties of the fiber, and may lower the entrance pressure of spinning nozzle to enable spinning of polymer resin having high viscosity, that is, high molecular weight, and may improve productivity by increasing a take-up velocity and a draw ratio is provided, the technique may be widely applied in related fields.
An aspect of the present disclosure is to provide a method of manufacturing a high-strength sheath-core type synthetic fiber which may, by optimally designing differences in thermal conductivity, specific heat, and elongation viscosity between polymer components in a fiber in a bicomponent melt spinning process, maximize improvement or suppression of structural development of each polymer component within the fiber on a spinning line, may enable changes in molecular chain entanglement and structural control, and may also enable uniform structural development in a cross-sectional direction of fiber.
Another aspect of the present disclosure is to provide a sheath-core type synthetic fiber having improved tensile strength and elongation at break point.
An aspect of the present disclosure provides a method of manufacturing a high-strength sheath-core type synthetic fiber including forming a fiber by melt-spinning thermoplastic polymers consisting of a sheath component and a core component through a spin pack including a sheath-core type bicomponent spinning nozzle; performing a heat treatment by allowing a molten fiber to pass through a heating zone disposed directly below the spinning nozzle during the melt-spinning; cooling the heat-treated fiber; and drawing the cooled fiber, wherein the sheath component includes a resin having elongation viscosity and thermal conductivity lower and specific heat higher than those of a resin included in the core component.
Another aspect of the present disclosure provides a sheath-core type synthetic fiber formed of a sheath component and a core component, wherein the sheath component includes a resin having elongation viscosity and thermal conductivity lower and specific heat higher than those of a resin included in the core component.
The method of manufacturing high-strength synthetic fiber according to the present disclosure may be a method of optimizing an instantaneous local heating method directly below a spinning nozzle when spinning fiber with two or more polymer components in a bicomponent melt spinning process, and more particularly, by optimally designing differences in thermal conductivity, specific heat, and elongation viscosity between polymer components in the fiber in the commercialized bicomponent melt spinning process, improvement or suppression of structural development of each polymer component in the fiber on a spinning line may be maximized, structural control of molecular chain entanglement and more uniform structural development in the cross-sectional direction may be enabled with respect to components having improved structural development, and instantaneous high-temperature local heating may be performed on a molten state bicomponent fiber extruded from a nozzle hole, such that molecular chain entanglement control may be further improved, and mechanical properties may be further improved. Also, entrance pressure of spinning nozzle may be lowered, such that spinning of polymer resin of high viscosity, that is, high-molecular weight, may be performed, and by increasing a take-up velocity and a draw ratio, productivity of high-strength fiber may be improved. Accordingly, based on price competitiveness due to mass production and low cost, and control of physical properties of various fibers, the method may be used in industrial applications such as tire cords, transportation interior materials for automobiles, trains, aircraft, and ships, civil engineering and construction materials, electronic materials, ropes and nets, and may also be useful in manufacturing bicomponent fiber for clothing and household purposes such as lightweight sportswear and workwear, military uniforms, furniture and interior, and sporting goods, such that the method may be applied to a wide range of markets related thereto, such as fields of manufacturing films, sheets, molding, and containers.
Hereinafter, preferable embodiments of the present invention will be described with reference to the accompanied diagrams. However, the embodiment of the present invention may be modified into various different embodiments, and the scope in the present invention is not limited to the embodiments described below.
According to the present disclosure, a method of manufacturing a high-strength sheath-core type synthetic fiber is provided, and the method may include forming a fiber by melt-spinning a thermoplastic polymer of a sheath component and a core component through a spinning pack including a sheath-core type bicomponent spinning nozzle; performing a high-temperature heat treatment by allowing a molten fiber to pass through a heating zone disposed directly below the spinning nozzle during the melt-spinning; cooling the heat-treated as-spun fiber; and drawing the cooled as-spun fiber, wherein the sheath component includes a resin having elongation viscosity and thermal conductivity lower and specific heat higher than those of a resin included in the core component.
The sheath-core type synthetic fiber of the present disclosure may include an islands-in-the-sea type fiber. When the sheath-core type fiber is an islands-in-the-sea type fiber, a volume ratio (%) of sea component:island component may be 0.1:99.9 to 99.9:0.1, for example, 10:90 to 90:10, preferably 20:80 to 80:20. Meanwhile, the number of island fibers in the islands-in-the-sea type fiber may range from 1 to 1,000,000.
In greater detail, the present disclosure may include melting two or more thermoplastic polymers having different thermal conductivity, specific heat, and elongation viscosity depending on temperature, or the like, through different extruders, through each gear pump, supplying a predetermined amount and ratio thereof to a bicomponent spinning pack of, for example, a sheath-core type consisting of one or more cores (islands, ), for example, an islands-in-the-sea type, forming a flow with a sheath-core type, for example, an islands-in-the-sea type, consisting of one or more cores (islands,
) within a hole of a spinning nozzle including at least one nozzle hole, using a distribution plate, performing a high-temperature heat treatment directly or indirectly thereon by allowing the molten polymer flow on the fibers to pass through the heating zone 80 disposed in the vicinity of the spinning nozzle hole 51, cooling the heat-treated and extruded islands-in-the-sea type as-spun fiber, and drawing and performing a heat treatment on the cooled as-spun fiber, and may further include winding the drawn fiber.
The heating zone 80 may be performed by locally heating the fiber by a nozzle heating element formed as a circular-type 81a or a strip-type 81b at the periphery of the spinning nozzle hole.
A thermoplastic polymer of the sheath component and the core component may be independently selected from a group consisting of at least one polyester-based polymer selected from a group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polycyclohexanedimethanol terephthalate (PCT), polylactic acid (PLA), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), and polyarylate (PAR); at least one polyamide-based polymer selected from among nylon 6, nylon 6,6, nylon 4 and nylon 4,6; and at least one polyolefin-based polymer selected from a group consisting of polyethylene and polypropylene, but the raw material polymer may be employed without limitations among conventional thermoplastic polymers.
In the manufacturing method of the present disclosure, two or more polymer resins used in bicomponent spinning may improve or suppress structural development of each component within the fiber polymer in the spinning line, molecular chain entanglement may be addressed, to induce more uniform structural development in the cross-sectional direction of fiber, among the thermoplastic polymers, a polymer resin having a difference in thermal conductivity of more than 0.01 J/m·s·K and specific heat of more than 0.05 KJ/Kg·K at the same melt-spinning temperature may be selected, and also, to develop elongation viscosity differently depending on temperature on the spinning line, a polymer resin satisfying at least one of the conditions as below: melt viscosity of 10 poise or more, glass transition temperature (Tg) of 5° C. or more, and crystallinity temperature difference of 5° C. or more may be used. For example, a difference in thermal conductivities of thermoplastic polymers between the sheath component and the core component may be 0.01 J/m·s·K to 10 J/m·s·K, and a difference in specific heats therebetween may be 0.05 KJ/Kg. K to 50 KJ/Kg·K, and the thermoplastic polymer of the sheath component and the core component may satisfy at least one of the conditions as below: melt viscosity of 10 poise to 10,000 poise, glass transition temperature (Tg) of 5° C. to 300° C., and crystallinity temperature of 5° C. to 300° C.
The bicomponent spinning nozzle applied to the present disclosure may be designed to be formed as a sheath-core having one core or more islands-in-the-sea, and as described above, a polymer resin having a component with relatively low thermal conductivity, relatively high specific heat, and relatively low elongation viscosity may be supplied as a sheath component.
As an example of present disclosure, polyethylene terephthalate (PET) and/or nylon 6 may be provided as an island component or a core component, and polypropylene may be provided as a sea component or a sheath component.
In the method of manufacturing a high-strength sheath-core type synthetic fiber in the present disclosure, during the melt-spinning, the bicomponent fiber may pass through a heating zone 80 disposed immediately below the spinning nozzle 52, and the heating zone may include a nozzle heating element 81 formed to have a hole type 81a or a strip type 81b at the periphery of the hole.
Hereinafter, referring to the drawings,
The spinning nozzle 52 may form the bicomponent fiber F by spinning two or more thermoplastic resins in the molten state through the nozzle hole 51, and during the spinning, the bicomponent fiber F may pass through a heating means and may be heat-treated, the heat-treated bicomponent as-spun fiber may be cooled, the cooled as-spun fiber F may be drawn using a drawing machine, and may be wound.
In this case, the heating means directly below the spinning nozzle 52 may include a heating element 81 forming a hole-type heating hole 81a having the same structure and the same number as those of the nozzle hole of the spinning nozzle 52, and during spinning, the bicomponent fiber F may pass through each heating hole 81a, and may not be in direct contact with the heating hole 81a when passing through the heating hole 81a.
To this end, a distance al from an inner surface of the heating hole 81a to a center of the fiber F may be preferably determined in a range of 1 to 300 mm, more preferably in a range of 1 to 100 mm, and the heating hole 81a of this hole type may maintain a uniform temperature at the same distance in the 360° direction from the center of fiber F.
Also, as a modified example of the heating hole 81a, as illustrated in
In the strip-type heating hole 81b, similarly to the hole-type heating hole 81a, the distance al between the inner heating surface and the center of fiber F may be determined in a range of 1 to 300 mm, more preferably in a range of 1 to 100 mm. Also, the nozzle holes between the nozzle heating elements may be preferably arranged in a row in the center, or may be arranged in two or more rows within the allowable range of spinning properties or physical property deviation.
Referring back to
In this case, as illustrated in the enlarged diagram in
Therefore, the heating zone 80 may primarily directly heat the molten islands-in-the-sea type resin, for example, the sheath-core type resin, by the insertion length b2 and the gap b4 of the heating element 81 inserted into the lower portion of the spinning nozzle 52, and may indirectly heat the bicomponent fiber F in a molten state extruded from the nozzle 52 after spinning by the extension length b3 of the heating element 81, which extends in a length of −50 to 500 mm.
The heating zone 80 of the above an embodiment may transfer high-temperature heat directly to the vicinity of the nozzle hole 51 of the spinning nozzle 52 due to a structural change of the lower end in the actual commercialized nozzle 52, and may optimize with a dual heating heat transfer method of indirectly heating the bicomponent fiber F by the heating element 81 formed directly below the nozzle 52, such that, the drawing and mechanical properties of the polymer component within the bicomponent fiber obtained by controlling the molecular chain entanglement structure within the molten polymer through instantaneous high-heating may be further improved, and the cooling speed may be delayed, thereby increasing the take-up velocity and the drawing speed and improving productivity.
Accordingly, in the embodiment of the present disclosure, the structure of the lower portion of the spinning nozzle 52, which may be actually commercialized, may be changed, and may be applied immediately, thereby lowering the initial investment cost and improving productivity of the high-strength synthetic fiber at low cost.
Further, by using the method of manufacturing a high-strength sheath-core type synthetic fiber in the present disclosure, with respect to the heating means of the embodiment, it may be preferable to optimize the ratio, residence time, flow rate and shear rate of two or more components passing through each nozzle hole 51 of the nozzle 52.
Accordingly, each molten polymer in the bicomponent fiber extruded per hole may need to allow one component to be extruded at a rate of at least 0.1% volume weight or more. For example, the volume ratio between the sheath portion and the core portion in the sheath-core type fiber may be preferably in the range of 0.1:99.9 to 99.9:0.1.
Meanwhile, the residence time of the polymer per hole may be 3 seconds or less, and the flow rate may be at least 0.01 cc/min and 10 cc/min or less. In this case, for example, in the case of polyester polymer, when the residence time exceeds 3 seconds, the molten polymer may be exposed to excessive heat for a long time, causing a thermal degradation problem, and when the flow rate is less than 0.01 cc/min, excessive heat may be exposed to the molten polymer, causing a thermal degradation problem, which is not preferable. The residence time and the flow rate may be varied depending on the type of polymer.
Also, preferably, the shear rate of the polymer on the wall surface of nozzle hole 51 in the nozzle 52 in an embodiment of the present disclosure may be 500 to 500,000/sec, and when the shear rate is less than 500/sec, the molecular orientation and entanglement structure control effect of the molten polymer may be reduced due to low shear stress, and when the shear rate exceeds 500,000/sec, melt fracture may occur due to viscoelastic properties of the molten polymer, which may cause unevenness of the cross-section of the fiber.
In the spinning device applicable to the method of manufacturing a high-strength sheath-core type synthetic fiber in the present disclosure, the heating holes 81a and 81b of the heating element 81 may be designed to have the same structure as that of the nozzle hole 51 of the spinning nozzle 52, such that, after spinning, the extruded fiber F may be locally-heated by passing through the heating element 81. In particular, the hole-type heating hole 81a may maintain the structure of the nozzle hole 51 of the nozzle 52, and an inner circumferential surface thereof may be spaced within 1 to 300 mm from a center of nozzle hole 51 of nozzle 52, such that the temperature may be maintained at the same distance in the 360° direction from the center of each nozzle hole 51 of the spinning nozzle 52 (see
Also, the strip-type heating hole 81b may have a linear structure facing 180° around the nozzle hole 51 of the nozzle 52, a structure formed to be symmetrical within 1 to 300 m from the center of nozzle hole 51 (see
In this case, the heating holes 81a and 81b may be designed by an indirect heating method in which the bicomponent fiber F passing therethrough after spinning may not be in direct contact with heat, and when the heated surfaces of the heating holes 81a and 81b are close than 1 mm from a center of the nozzle hole 51 of nozzle 52, it may be highly likely that the heating element 81 may be in contact with the fiber F such that contamination of the heating element 81 and breakage of the fiber F may occur, which may cause poor fiber quality and workability. When exceeding 300 mm, sufficient heat may not be transferred to the fiber F, such that it may be difficult to control the molecular chain entanglement structure within the molten fiber polymer and the effect of improving physical properties may be lowered, which may not be preferable.
As for the structure of the nozzle hole 51 of the nozzle body 52, as illustrated in
The number of the hole-type heating hole 81a of the heating element 81 and the structure thereof in the present disclosure may be the same as those of the nozzle hole 51 structure of the spinning nozzle 52, and accordingly, overall shapes of a nozzle structure such as circular, oval, square, and toroid shapes.
Also, the heating element 81 may be applied as a normal electric heating wire, and may be implemented as, for example, Cu-based and Al-based cast heater, electromagnetic induction heater, sheath heater, flange heater, cartridge heater, coil heater, near-infrared heater, carbon heater, ceramic heater, PTC heater, quartz tube heater, halogen heater, nichrome heater, mica heater, aluminum nitride (AIN) heater, or the like.
In a preferred embodiment of the spinning nozzle for manufacturing high-strength thermoplastic bicomponent fiber applicable to the present disclosure, a difference in temperatures between the heating element 81 and the pack body 60 may be 0 to 1,000° C., and the heating element 81 may be provided at a temperature at least equal to or higher than the pack body 60 temperature.
Also, the distribution plate 55 and the nozzle 52 may be fixed within the pack body 60 maintained at 50 to 500° C. from the heat source of the pack body heater 70, and the temperature of the distribution plate 55 and the nozzle 52 may be the same as the temperature of the pack body heater 70. In the above description, when the temperature of the pack body 60 is less than 50° C., most of the resin may not be melted, making it difficult to conduct melt spinning, and when it exceeds 500° C., rapid thermal degradation of the resin may occur such that physical properties of the fiber may thermal degraded, which may not be preferable. In this case, the temperature of the pack body heater 70 may be controlled by an electric heater or heating medium. However, the temperature range of the heat source may be varied depending on the type of polymer.
Afterwards, polymer of two or more molten components may form and extrude a islands-in-the-sea type bicomponent fiber through the distribution plate 55 and the spinning nozzle.
In particular, as the most preferable example of the present disclosure, an islands-in-the-sea type bicomponent fiber using PET, Nylon and PP polymer may be used, but is not limited to the above material, and the embodiment may be applied to fiber fields such as long fiber, short fiber, and non-woven fabric of the above material, and may also be applied to manufacturing fields such as a film, sheet, molding, and a container.
The spinning nozzle device in an embodiment applicable to the present disclosure may be applied to a mono yarn bicomponent melt spinning process using two or more types of thermoplastic polymers as raw materials.
Specifically, the device may be applied to the bicomponent spinning process for sheath-core, for example, islands-in-the-sea type mono yarn, and the take-up velocity may be 0.1 to 200 m/min, preferably 3 to 200 m/min, and a mono yarn bicomponent fiber having a diameter of 0.001 to 3 mm, for example, 0.05 to 1 mm, may be provided.
Also, the local-heating method directly below the spinning nozzle applied in the present disclosure may be applied to a bicomponent spinning process for long fiber (filament) of 100 d/f or less, using a low-speed spinning method (UDY, 100˜2000 m/min), a mid-speed spinning method (POY, 2000˜4000 m/min), high-speed spinning method (HOY, 4000 m/min or more), direct spinning and drawing method (SDY), and off-line drawing method.
Also, by applying the method to the short fiber (staple fiber) bicomponent spinning process, the spinning may be performed at take-up velocity: 5˜3000 m/min, such that a fiber having a diameter of 100 d/f or less may be provided, and the method may be applied to bicomponent spinning-type nonwoven fabric (Spun-bond and melt blown, or the like) processes for implementing a take-up velocity of 100˜6000 m/min and a fiber diameter of 100 d/f or less.
The method of manufacturing high-strength synthetic fiber according to the present disclosure may be obtained by optimizing two or more polymer composition and instantaneous local heating methods directly below the spinning nozzle when spinning a fiber in a bicomponent melt spinning process, and by optimally designing differences in thermal conductivity, specific heat, and elongation viscosity between the two polymer components within the fiber in the actually commercialized bicomponent melt spinning process, In the spinning line, structural development of each polymer component within the fiber may be maximized or suppressed, and also, structure control of molecular chain entanglement and more uniform structural development in the cross-sectional direction may be possible with respect to a component having improved structural development. Also, by instantaneous high-temperature local heating of the molten bicomponent fiber extruded in the vicinity of the nozzle hole, the molecular chain entanglement and structure control may be further improved, such that mechanical properties may be further improved, and further, spinning of polymer resin having high viscosity a (high-molecular weight), which has not be possible before, may be possible, and as a take-up velocity and a draw ratio are increased, productivity of a high-strength fiber may be further improved than before.
During spinning in the bicomponent melt spinning process of the present disclosure, as for the method of manufacturing high-strength synthetic fiber using differences in thermal conductivity, specific heat, elongation viscosity, or the like between polymer components within a bicomponent fiber and also optimizing a heating method directly below the spinning nozzle may, by simply changing the commercially available bicomponent spinning nozzle and using existing processes such as a bicomponent melt spinning process and a drawing process, improve physical properties, such that initial investment costs may be lowered, and mass production and high-performance fiber production at low cost may be possible.
Accordingly, in the present disclosure, two or more thermoplastic polymers may be used as raw materials and may be heated by instantaneous local high-temperature heating directly below the nozzle during bicomponent melt spinning, and may be spun, drawn, and heat-treated, and accordingly, despite the local high-temperature heating described above, thermal degradation problems of polymers may not occur, intrinsic molecular weight may be maintained, and a high-strength synthetic fiber having improved strength and elongation may be provided.
The description in relation to the method of manufacturing a high-strength sheath-core type synthetic fiber in the present disclosure may also be applied to a sheath-core type synthetic fiber.
According to another aspect of the present disclosure, a sheath-core type synthetic fiber in which a sheath component has lower elongation viscosity and thermal conductivity than those of the core component, and which may be formed of resin having high specific heat may be manufactured. The sheath-core type synthetic fiber may be, for example, islands-in-the-sea fiber, in which the sea component may correspond to the sheath component and the island component may correspond to the core component.
For example, the sheath-core type synthetic fiber may be an islands-in-the-sea type fiber in which the island component has a diameter of 10 nm to 500 μm and a strength of 5 g/d to 30 g/d, for example, an islands-in-the-sea fiber containing polyethylene terephthalate (PET) island yarn. In other words, according to the present disclosure, the sea component may be extracted from the islands-in-the-sea type fiber manufactured through the above manufacturing method using a solvent generally used in the art such as an organic solvent and an aqueous alkaline solution, and a high-strength PET fiber having a strength of 11 g/d or more may be provided.
In particular, the present disclosure may include an island component having an intrinsic viscosity (I.V.) of 0.5 to 3.0, more preferably 0.5 to 1.5, wherein the island component may be a polyethylene terephthalate (PET) polymer, and the PET polymer may go through a islands-in-the-sea type bicomponent melt spinning with polymers having different thermal conductivity, specific heat, and elongation viscosity, and the bicomponent fiber may be heated by an instantaneous local high-temperature heating method directly below the nozzle, and may be cooled and drawn, thereby providing a high-strength PET fiber satisfying physical properties greater than strength calculated by Equation 1 below.
For example, the intrinsic viscosity (I.V.) measurement method of the PET fiber may include dissolving 0.1 g of a sample in a reagent mixing phenol and 1,1,2,2-tetrachloroethane at a 6:4 (weight ratio) for 90 minutes such that a concentration thereof may become 0.4 g/100 , transferring to an Ubbelohde viscosity meter and maintaining in a constant temperature bath at 30° C. for 10 minutes, and obtaining the number of seconds the solution falls using a viscosity meter and aspirator.
The number of seconds the solvent falls was also calculated using the formula below for the R.V. value and I.V. value (Billmayer approximation) obtained in the same manner as above.
Accordingly, through the instantaneous local high-temperature heating method directly below the bicomponent melt spinning and the nozzle of the present disclosure, a high-strength polymer fiber having relatively high physical properties which has not been obtained from the intrinsic viscosity (I.V., molecular weight) of each existing fiber, for example, high-strength PET fibers, may be provided.
Also, according to the present disclosure, a high-strength nylon fiber having a strength of 10.5 g/d or more may be manufactured. In particular, in the present disclosure, a bicomponent melt spinning a nylon polymer having a relative viscosity (Rv) of 2.0 to 5.0, more preferably 2.5 to 3.5, with a polymer having different thermal conductivity, specific heat, and elongation viscosity, to form an islands-in-the-sea type fiber, and the bicomponent fiber may be heated by the instantaneous local high-temperature heating method directly below the nozzle, and may be cooled and drawn, thereby providing a high-strength nylon fiber satisfying physical properties greater than strength calculated by Equation 2 below.
The relative viscosity (R.V.) measurement method of nylon fiber may include dissolving 0.1 g of sample in 96% sulfuric acid for 90 minutes to a concentration of 0.4 g/100 ml, transferring to an Ubbelohde viscosity, and maintaining in a thermostat at 30° C. for 10 minutes, and the number of seconds the solution falls was obtained using a viscosity meter and an aspirator.
The number of seconds the solvent falls was obtained in the same manner and calculated using an R.V. value calculation formula as below.
R.V.=Number of seconds the sample falls/number of seconds the solvent falls
Accordingly, the instantaneous local high-temperature heating method directly below the bicomponent melt spinning and nozzle of the present disclosure, a high-strength polyamide fiber having relatively high physical properties which has not been obtained from the relative viscosity (R.V., molecular weight) of each existing fiber may be provided.
Meanwhile, the melt flow index (MFI) measurement method of PP resin used in the sea component of bicomponent spinning may be obtained according to ASTM D1238 (MFI 230/2), and specifically, PP resin may be melted at 230° C. for about 6 minutes, pressure may be applied with a weight of 2.16 kg using a nozzle having a diameter of 2 mm, and a weight (g/10 min) of resin extruded for 10 minutes may be measured.
Furthermore, when the sheath-core type synthetic fiber of the present disclosure has two or more melting point peaks on the DSC of the core component, the temperature difference between the peaks may be less than 10° C., for example, less than 10° C. More specifically, in the case of single melt-spinning using a single component raw material of high viscosity, that is, high-molecular weight, in low-speed spinning with a slow take-up velocity, the fiber may be cooled (solidified) by the air of low temperature after extrusion, and in this case, the thickness thereof may be very thin, such that there may be almost no temperature deviation in the cross-sectional direction of fiber. In other words, since uniform cooling may be performed downstream in the cross-section direction, the melting point peak on the DSC of the fiber obtained therefrom may mostly have one peak. On the other hand, in the case of high-speed spinning with a high take-up velocity, friction between the surface of the fiber and the surrounding air may increase, such that the surface may be cooled quickly and the center may be cooled relatively slowly. Accordingly, even though the fiber is extremely thin, a temperature difference may increase downwardly in the cross-sectional direction of fiber, and accordingly, viscosity of the fiber surface may increase faster, and spinning stress may be concentrated in the portion having increased viscosity, such that excessive structural development, that is, orientation, or orientation-induced crystallinity may occur only on the fiber surface, and structural development may not occur in the central portion, and accordingly, uneven structural development may occur in the cross-section direction. In this case, when imaging a DSC of the fiber, two or more melting point peaks may occur, and the larger the difference in structural development between the surface and the central portion, the larger the temperature difference between the peaks may become. As for the sheath-core type synthetic fiber in the present disclosure, when two or more melting point peaks are present on the DSC of the core component, the temperature difference between the peaks may be maintaining below 10° C., indicating that the uneven structure may be improved.
In other words, during spinning through sheath-core type bicomponent spinning, such as synthetic fiber of the present disclosure, when a component in which the sheath component has lower elongation viscosity and thermal conductivity than those of the core component and has higher specific heat is used, even in high-speed spinning, the effect of reducing a difference in cooling deviation and structural development of the core component in the cross-sectional direction of fiber may be obtained. Accordingly, when imaging the core component using DSC, it may be less likely that two melting point peaks appear, and even when two or more melting point peaks are present on the DSC of the core component, as compared to the case of single spinning, the temperature difference between peaks may be relatively small and may be maintained below 10° C.
The present disclosure provides the islands-in-the-sea type high-strength synthetic fiber from the manufacturing method described above, and based on mass production, price competitiveness due to low cost, and control of various fiber properties, the fiber may be useful for marine and military purposes such as a tire cord, transportation interior material for automobiles, trains, aircraft, and ships, civil engineering and construction materials, electronic materials, a rope and net, and may also be useful for lightweight sportswear and workwear, military uniform, furniture and interior design, sporting goods, clothing and daily use, such that a wide market may be assured.
Hereinafter, the present disclosure will be described in greater detail through specific embodiments. The embodiments below are merely examples to help understand the present disclosure, and the scope of the present disclosure is not limited thereto.
Although the embodiment of present disclosure has been described in detail above, the scope of rights of present disclosure is not limited thereto, and it would be obvious for a person skilled in the art that various modifications and variations may be made without departing from the technical idea of present disclosure described in the claims.
Polyethylene terephthalate (PET) resin (intrinsic viscosity 1.18 /g) was put in an extruder and was melt-extruded, and inserted into a single component spinning nozzle at a temperature of 290° C. In this case, the spinning nozzle was disposed in an enclosed form within a pack body maintained at a constant temperature by a pack-body heater, and a lower portion of the lower portion of the spinning nozzle was recessed inwardly by 10 mm from a lower portion of the pack body. High-speed spinning was performed using the single component spinning device at various take-up velocity, such that an as-spun fiber was manufactured, and by off-line drawing the as-spun fiber obtained from the low-speed spinning, a high-strength drawing fiber was manufactured.
Polyethylene terephthalate (PET) resin (intrinsic viscosity 1.18 /g) and polypropylene (PP) resin (MFI 30) were put in two different extruders, melt-extruded and inserted into an islands-in-the-sea type spinning nozzle having a temperature of 290° C. In this case, the spinning nozzle was disposed in an enclosed form within the pack body maintained at a constant temperature by a pack-body heater, and a lower portion of the spinning nozzle was recessed inwardly by 10 mm from a lower portion of the pack body. High-speed spinning was performed using the bicomponent spinning device at various take-up velocity, such that an as-spun bicomponent fiber was manufactured, and by off-line drawing the as-spun bicomponent fiber obtained from the low-speed spinning, a high-strength drawing fiber was manufactured.
Polyethylene terephthalate (PET) resin (intrinsic viscosity 1.18 /g) and polypropylene (PP) resin (MFI 30) were put in two different extruders, melt-extruded and inserted into an islands-in-the-sea yarn type spinning nozzle having a temperature of 290° C. In this case, the spinning nozzle was disposed in an enclosed form within the pack body maintained at a constant temperature by a pack-body heater, a lower portion of the spinning nozzle protruded 10 mm outwardly from a lower portion of the pack body, and a heating element 81b having a strip-type heating zone surrounding circular holes at a predetermined distance from a center of the spinning nozzle was disposed in the nozzle lower end portion to be in contact with and recessed inwardly from the lower portion of the nozzle, and a heating zone 80 to directly/indirectly heat the fiber just before and after extrusion was formed. High-speed spinning was performed using the bicomponent spinning device at various take-up velocity, such that an as-spun bicomponent fiber was manufactured, and by off-line drawing the as-spun bicomponent fiber obtained from the low-speed spinning, a high-strength drawing fiber was manufactured.
1Measured with as-spun fiber obtained by free fall
2Measurement method: PET component strength (g/d) in islands-in-the-sea type bicomponent fiber = islands-in-the-sea yarn fiber strength (g/d)/weight ratio of PET component in islands-in-the-sea yarn fiber (0.5)
3)Draw ratio = final drawing roller speed / supply drawing roller speed
4)DSC measurement (temperature increase speed: 20° C./min)
According to the results of Table 1 above, as for the polyethylene terephthalate (PET) resin of embodiment 1 and embodiment 2 manufactured through the islands-in-the-sea type bicomponent spinning high-temperature heating directly below the nozzle, there was no significant difference in changes in intrinsic viscosity of the fiber during the spinning process as compared to comparative example 1, which indicates that thermal decomposition problems due to process differences, that is, molecular weight reduction, did not occur.
Also, the maximum take-up velocity and draw ratio under the spinning and drawing conditions of embodiment 1 and embodiment 2 above increased further than the take-up velocity and draw ratio in the conventional method (comparative example 1) performed by single spinning without instantaneous high-temperature local heating directly below the nozzle. Accordingly, it was confirmed that, by controlling the molecular chain entanglement within the fiber by the bicomponent spinning method, productivity was improved.
In particular, in embodiment 2, as productivity was further improved by more than 258, it was confirmed that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the nozzle during bicomponent spinning was more preferable.
Also, the physical properties such as tensile strength of PET fiber obtained at the maximum take-up velocity and draw ratio of embodiment 1 and embodiment 2 was higher than the physical properties of fiber obtained by the conventional method (comparative example 1) performed by single spinning without instantaneous high-temperature local heating directly below the nozzle. Accordingly, it was confirmed that the physical properties were improved by controlling the molecular chain entanglement within the fiber by the bicomponent spinning method.
In particular, in embodiment 2, since tensile strength was further improved by 25% or more, it was confirmed that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the nozzle during bicomponent spinning was more preferable.
Also, it was confirmed that the nozzle pressure applied to a front end of the spinning nozzle during spinning in embodiments 1 and 2 was lower than the conventional method (comparative example 1) in which spinning was performed alone without instantaneous high-temperature local heating directly below the nozzle. Accordingly, it was confirmed that the entrance pressure of spinning nozzle was lowered by controlling the molecular chain entanglement within the molten polymer by the bicomponent spinning method, and accordingly, the risk of equipment damage due to high pressure within the equipment may be lowered, and spinning may be performed a longer period of time, such that it is expected that productivity may improve. Also, spinning may be performed to a resin having high-molecular weight in which it may be difficult to perform spinning due to high entrance pressure of spinning nozzle.
In particular, in embodiment 2, the entrance pressure was lowered by 40% or more, such that it was confirmed that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the nozzle during bicomponent spinning was more preferable.
Also, the temperature difference between the two melting points (Tm) appearing during DSC thermal analysis of PET as-spun fiber obtained at the maximum take-up velocity in embodiment 1 and embodiment 2 was lower than the temperature difference of the fiber obtained from the conventional method (comparative example 1) performed by single spinning without instantaneous high-temperature local heating directly below the nozzle.
Accordingly, by the bicomponent spinning method in the present disclosure, due to the PP resin of the sea component having relatively lower thermal conductivity and higher specific heat than those of PET resin of the island component, a cooling deviation from the spinning line in the cross-section direction within the PET fiber may be reduced, and a more uniform structural development and orientation-induced crystal structure of fiber may be obtained, which may further contribute to the improvement of the mechanical properties of the fiber.
In particular, in embodiment 2, the temperature difference was further lowered to 6° C. or less, such that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the bicomponent spinning nozzle was more preferable.
Nylon 6 resin (Rv 3.4) was put in an extruder, melt-extruded and inserted into a single component spinning nozzle at a temperature of 260° C. In this case, the spinning nozzle was disposed in an enclosed form within the pack body maintained at a constant temperature by a pack-body heater, and the lower portion of the spinning nozzle was recessed inwardly by 10 mm from the lower portion of the pack body. High-speed spinning was performed using the single component spinning device at various take-up velocity, such that an as-spun fiber was manufactured, and by off-line drawing the as-spun fiber obtained from the low-speed spinning, a high-strength drawing fiber was manufactured.
Nylon 6 resin (Rv 3.4) and polypropylene (PP) resin (MFI 30) were put in two different extruders, melt-extruded and inserted into an islands-in-the-sea yarn-type spinning nozzle at a temperature of 260° C. In this case, the spinning nozzle was disposed in an enclosed form within the pack body maintained at a constant temperature by a pack-body heater, and the lower portion of the spinning nozzle was recessed inwardly by 10 mm from the lower portion of the pack body. High-speed spinning was performed using the bicomponent spinning device at various take-up velocity, such that an as-spun bicomponent fiber was manufactured, and by off-line drawing the as-spun bicomponent fiber obtained from the low-speed spinning, a high-strength drawing fiber was manufactured.
Nylon 6 resin (Rv 3.4) and polypropylene (PP) resin (MFI 30) were put in two different extruders, melt-extruded, and inserted into an islands-in-the-sea yarn-type spinning nozzle at a temperature of 260° C. In this case, the spinning nozzle is disposed in an enclosed form within the pack body maintained at a constant temperature by a pack-body heater, a lower portion of the spinning nozzle protruded 10 mm outwardly from a lower portion of the pack body, and a heating element 81b having a strip-type heating zone surrounding circular holes at a predetermined distance from a center of the spinning nozzle was disposed in the nozzle lower end portion to be in contact with and recessed inwardly from the lower portion of the nozzle, and a heating zone 80 to directly/indirectly heat the fiber just before and after extrusion was formed. High-speed spinning was performed using the bicomponent spinning device at various take-up velocity, such that an as-spun bicomponent fiber was manufactured, and by off-line drawing the as-spun bicomponent fiber obtained from the low-speed spinning, a high-strength drawing fiber was manufactured.
1Measured with as-spun fiber obtained by free fall
2Measurement method: Nylon 6 component strength (g/d) in islands-in-the-sea yarn fiber = islands-in-the-sea yarn fiber strength (g/d)/weight ratio of Nylon 6 component in islands-in-the-sea yarn fiber (0.5)
3)draw ratio = final drawing roller speed / supply drawing roller speed
According to the results of Table 2, as for the Nylon 6 resin in embodiment 3 and embodiment 4 manufactured through the islands-in-the-sea bicomponent spinning and local high-temperature heating directly below the nozzle, there was no significant difference in changes in intrinsic viscosity of the fiber during the spinning process as compared to comparative example 1, which indicates that thermal decomposition problems due to process differences, that is, molecular weight reduction, did not occur.
Also, the maximum take-up velocity and draw ratio under the spinning and drawing conditions of embodiment 3 and embodiment 4 above increased further than the take-up velocity and draw ratio in the conventional method (comparative example 1) performed by single spinning without instantaneous high-temperature local heating directly below the nozzle. Accordingly, it was confirmed that, by controlling the molecular chain entanglement within the fiber by the bicomponent spinning method, productivity was improved. Also, in embodiment 4, productivity was further improved by more than 25%, which may indicate that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the nozzle during bicomponent spinning was more preferable.
Also, the physical properties such as tensile strength of Nylon 6 fiber obtained at the maximum take-up velocity and draw ratio in embodiment 3 and embodiment 4 were higher than the physical properties of fiber obtained from a conventional method (comparative example 1) performed by single spinning without instantaneous high-temperature local heating directly below the nozzle. Accordingly, it was confirmed that the physical properties were improved by controlling the molecular chain entanglement within the fiber by the bicomponent spinning method.
In particular, tensile strength was further improved by 25% or more, it was confirmed that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the nozzle during bicomponent spinning was more preferable.
Also, it was confirmed that the nozzle pressure applied to a front end of the spinning nozzle during spinning in embodiments 3 and 4 was lower than that of the conventional method (comparative example 1) in which spinning was performed alone without instantaneous high-temperature local heating directly below the nozzle.
Accordingly, it was confirmed that the entrance pressure of spinning nozzle was lowered by controlling the molecular chain entanglement in the molten polymer by the bicomponent spinning method. Accordingly, the risk of equipment damage due to high pressure within the equipment may be lowered, and spinning may be performed a longer period of time, such that it is expected that productivity may improve. Also, spinning may be performed to a resin having high-molecular weight in which it may be difficult to perform spinning due to high entrance pressure of spinning nozzle.
In particular, since the entrance pressure was further lowered by 40% or more in embodiment 4, it was confirmed that the instantaneous high-temperature local heating of the fiber directly or indirectly directly below the nozzle during bicomponent spinning was more preferable.
While the example embodiments have been illustrated and described above, it will be configured as apparent to those skilled in the art that modifications and variations may be made without departing from the scope in the example embodiment as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0114197 | Sep 2022 | KR | national |
This application is a continuation of International Application No. PCT/KR2022/017735, filed on Nov. 11, 2022, which claims priority to Korean Patent Application No. 10-2022-0114197, filed on Sep. 8, 2022 with the Korean Intellectual Property Office, the disclosures of which are incorporated herein in their entireties by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2022/017735 | Nov 2022 | WO |
| Child | 18956495 | US |
