Divided composite fiber

Abstract

The split type composite fiber contains a polymer A and a polymer B. On the cross section of the fiber, the polymer A is continuously distributed, the polymer B is divided into large split blocks and small split blocks, and all the split blocks are exposed out of the surface of the fiber; the cross section of the single fiber is provided with 1-3 maximum segmentation blocks with the same area and more than two small segmentation blocks with the area smaller than that of the maximum segmentation blocks; the area of the single maximum segmentation block accounts for 7.5-70.0% of the cross sectional area of the fiber, and the area of the single maximum segmentation block is more than two times of the area of the single small segmentation block. The initial splitting rate of the split type composite fiber is low, chemical agents are not used, the split type composite fiber can be effectively split after physical treatment such as hot water, and the split type composite fiber is fluffy and soft.

Description

Split composite fiber Technical Field

[0001] The present invention relates to a split composite fiber, specifically, a split composite fiber composed of polymer A and polymer B, wherein polymer B is divided into large split blocks and small split blocks, and has a low initial fiber opening rate and a high fiber opening rate after boiling water treatment. Background Art

[0002] Synthetic fibers, such as polyester and polyamide, have gained significant market share in a variety of fields, including clothing, home interiors, vehicle interiors, and industrial materials, due to their excellent flexibility, elastic recovery, abrasion resistance, and alkali resistance. In recent years, differentiated fibers with diverse functions have been introduced to the market. Among these, synthetic split fibers and raw cotton, which can be used for cotton-like properties and industrial applications, are a major research and development focus.

[0003] Currently, technologies for obtaining fluffy, soft fibers by physically or chemically opening splittable composite fibers formed from two polymers with cross-sections in parallel, radial, or hollow shapes have been widely studied. Taiwan Patent TW200825225A discloses a splittable composite long fiber and a nonwoven fabric composed of the splittable composite long fiber. The fibers primarily utilize a propylene polymer with an MFR greater than or equal to 40 g / 10 min at a load of 2160 g and 230°C, and high-pressure low-density polyethylene (HPLDPE), with the propylene polymer and HPLDPE partially interconnected. Splitting the fibers using a high-pressure water jet can improve their splittability. However, the use of a high-pressure water jet for opening fibers is relatively demanding, increasing the cost of opening fibers. Chinese Patent CN101646813A discloses a splittable composite fiber composed of a polyamide composition and a fiber-forming polymer with no affinity for the polyamide composition. Splitting the fibers using a low concentration of benzyl alcohol or without the use of a swelling agent exhibits excellent splitting performance. However, it mainly uses aliphatic dicarboxylic acids and aromatic diamines as main structural units to form polyamide with high shrinkage performance, has high requirements on polymer performance, and is not suitable for the fiber opening process of split fibers formed by ordinary conventional polymers.

[0004] Summary of the Invention

[0005] The object of the present invention is to provide a split composite fiber which has a low initial fiber opening rate, can be effectively fiber-opened after being treated with physical means such as hot water without using chemical agents, and is fluffy and soft after fiber opening.

[0006] The technical solutions of the present invention are as follows:

[0007] A split composite fiber contains polymer A and polymer B. On the fiber cross section, polymer A is continuously distributed, and polymer B is divided into large segments and small segments, and all segments are exposed on the fiber surface; the single fiber cross section has 1 to 3 largest segments with the same area, and 2 or more small segments with smaller areas than the largest segments; the area of ​​the single largest segment accounts for 7.5 to 70.0% of the fiber cross section area, and the area of ​​the single largest segment is more than twice the area of ​​the single small segment.

[0008] The perimeter of the single largest segment is L1, the contact length between the single largest segment and polymer A is L2, and L2 / L1 is preferably 45-80%.

[0009] The angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section is preferably greater than 90°.

[0010] After the composite fiber is treated with boiling water, the shrinkage of polymer A is preferably greater than that of polymer B, and the difference is greater than 5%.

[0011] The difference in solubility parameters between polymer A and polymer B is preferably 1.0 to 10.8 J. 1 / 2 / cm 3 / 2 .

[0012] The polymer A and polymer B are preferably polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene, polyamide-6, polyamide-56, polyamide-66 or polyamide-610, respectively.

[0013] The area ratio of polymer A to polymer B in the cross section of the composite fiber is preferably 70:30 to 30:70.

[0014] The initial fiber opening rate of the composite fiber is preferably below 5%, and the fiber opening rate after the boiling water treatment is preferably above 90%.

[0015] The composite fiber is preferably a short fiber with an initial fiber opening rate of less than 5%.

[0016] The water absorption rate of the polymer A is preferably below 1.5%.

[0017] This invention, through cross-sectional design of the splittable composite fiber, prioritizes the opening of the largest segment, creating space for movement, driving the opening of smaller segments and improving opening performance. Furthermore, in the preferred technical solution, the "anchoring effect" of the largest segment is avoided by controlling the contact length-to-circumference ratio and contact angle within the fiber, further facilitating opening. Furthermore, by exploiting the differences in polymer solubility parameters and controlling the water absorption of polymer A, the initial opening rate of both the splittable composite long and short fibers is kept below 5%, and after boiling water treatment, the opening rate is maintained above 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a schematic cross-sectional view of the split-type composite fiber of the present invention.

[0019] FIG2 is a schematic cross-sectional view of the split-type composite fiber of the present invention.

[0020] FIG3 is a schematic cross-sectional view of the split-type composite fiber of the present invention.

[0021] FIG4 is a schematic cross-sectional view of the split-type composite fibers of Examples 01 to 06, 14, and 18 of the present invention.

[0022] FIG5 is a schematic cross-sectional view of a split-type composite fiber according to Example 07 of the present invention.

[0023] FIG6 is a schematic cross-sectional view of a split-type composite fiber according to Example 08 of the present invention.

[0024] FIG7 is a schematic cross-sectional view of a split-type composite fiber according to Example 09 of the present invention.

[0025] FIG8 is a schematic cross-sectional view of a split-type composite fiber according to Example 10 of the present invention.

[0026] FIG9 is a schematic cross-sectional view of a split-type composite fiber according to Example 11 of the present invention.

[0027] FIG10 is a schematic cross-sectional view of a split-type composite fiber according to Example 12 of the present invention.

[0028] FIG11 is a schematic cross-sectional view of a split-type composite fiber according to Example 13 of the present invention.

[0029] FIG12 is a schematic cross-sectional view of a split-type composite fiber according to Example 15 of the present invention.

[0030] FIG13 is a schematic cross-sectional view of a split-type composite fiber according to Example 16 of the present invention.

[0031] FIG14 is a schematic cross-sectional view of a split-type composite fiber according to Example 17 of the present invention.

[0032] FIG15 is a schematic cross-sectional view of a split-type composite fiber according to Example 19 of the present invention.

[0033] FIG16 is a schematic cross-sectional view of a split-type composite fiber according to Example 20 of the present invention.

[0034] FIG17 is a schematic cross-sectional view of the split-type conjugate fiber of Comparative Example 01 of the present invention.

[0035] FIG18 is a schematic cross-sectional view of the split-type conjugate fiber of Comparative Example 02 of the present invention.

[0036] FIG19 is a schematic cross-sectional view of the split-type conjugate fiber of Comparative Example 03 of the present invention.

[0037] FIG20 is a schematic cross-sectional view of the split-type conjugate fiber of Comparative Example 04 of the present invention.

[0038] In Figures 1 to 3, S represents the overall area of ​​the fiber cross-section, S1 represents the area of ​​the single largest segment on the fiber cross-section, S2 represents the area of ​​a single small segment on the fiber cross-section, L1 represents the circumference of the single largest segment, and L2 represents the contact length between the single largest segment and polymer A. DETAILED DESCRIPTION

[0039] The split-type composite fiber of the present invention has two polymers on its cross section, namely polymer A and polymer B. The polymer A is continuously distributed, and the polymer B is divided into large blocks and small blocks, and all the blocks are exposed on the fiber surface.

[0040] During the melt spinning process of the split-type composite fiber, the segments formed by polymer B are arranged on the outside of the fiber. After being spun out from the spinneret, they are preferentially cooled. Then, under the traction of a certain spinning speed, polymer B is easily aligned, resulting in a high boiling water shrinkage rate of the segments in the split-type composite fiber, which is not easy to produce a shrinkage difference with polymer A, thereby hindering the fiber opening of the split-type composite fiber. Therefore, the present invention provides that the polymer B is divided into 1 to 3 largest segments with the same area and 2 or more small segments with an area smaller than the largest segment. The largest segment is not easy to align with the small segment during the melt spinning process, thereby maintaining a sufficient shrinkage difference between the largest segment and polymer A and easy to split. The largest segment can serve as the starting point for fiber opening of the split-type composite fiber during boiling water treatment. After the largest segment falls off, more movable space is created for polymer A, thereby promoting the fiber opening of the small segment.

[0041] On the cross-section of the split-type composite fiber, there are 1 to 3 largest segments of the same area, and the area of ​​a single largest segment accounts for 7.5 to 70.0% of the fiber cross-sectional area. When there are more than 3 largest segments, the fiber cross-sectional area occupied is too large, and the fiber formed by the largest segments after fiber opening has a large fineness, which is not conducive to providing a fluffy and soft feel; and although the largest segments are more conducive to fiber opening, it will also lead to a large initial fiber opening rate, affecting the passability of subsequent processing. When the area of ​​the single largest segment accounts for less than 7.5% of the fiber cross-sectional area, it is not conducive to fiber opening; when the area of ​​the single largest segment accounts for more than 70.0% of the fiber cross-sectional area, the fineness of the single fiber of the single largest segment is large, which is not conducive to providing a fluffy and soft feel. After boiling water treatment, in order to obtain excellent fiber opening performance and fluffy feel, the present invention preferably has an area of ​​the single largest segment account for 10.0 to 30.0% of the fiber cross-sectional area.

[0042] In addition to 1 to 3 largest segments of the same area, the cross section of the split composite fiber also has 2 or more small segments with an area smaller than the largest segment, that is, all segments with an area smaller than the largest segment are collectively referred to as small segments, and these small segments can be of the same size or different sizes.

[0043] To clearly distinguish the largest segments from the smaller segments, creating a distinct sensory perception of large and small, while also maintaining a high shrinkage differential between the largest segments and polymer A and providing a fluffy and soft feel, the present invention also limits the area of ​​a single largest segment to at least twice the area of ​​a single smaller segment. As long as the area ratio is met, the present invention does not impose any specific restrictions on the area range of the smaller segments; the area of ​​a single smaller segment can be less than or equal to 7.5% of the total cross-sectional area of ​​the composite fiber.

[0044] As is well known, the friction between two components is positively correlated with the force applied to the contact surface and negatively correlated with the contact surface area. The smaller the ratio of the contact length L2 of the single largest segment and polymer A to the circumference L1 of the single largest segment, the smaller the contact area between the single largest segment and polymer A, and the more conducive to the fiber opening of the split-type composite fiber. However, when the ratio of L2 / L1 is too small, that is, the contact area between the single largest segment and polymer A is small, although it is conducive to the fiber opening of the split-type composite fiber by boiling water treatment, it will also lead to a large initial fiber opening rate of the composite fiber, thereby affecting the subsequent preparation and processing of textiles. Therefore, the ratio of L2 / L1 described in the present invention is preferably 45% to 80%, and more preferably 45% to 70%.

[0045] At the same time, the angle between the largest segment and the fiber cross section, that is, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section, should not be too small. Otherwise, due to the "anchoring effect" during segmentation, the largest segment will not easily peel away from the space created by the contraction of polymer A, resulting in unsatisfactory fiber opening properties of the split composite fiber. In the present invention, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section is preferably greater than 90°.

[0046] To expedite the separation of the largest segment from polymer A, the boiling water shrinkage of polymer A after boiling water treatment is preferably greater than that of polymer B. After boiling water treatment, polymer A shrinks along the long axis of the composite fiber due to shrinkage stress. Based on the principle of constant mass and volume, polymer A expands and enlarges the cross-section of the composite fiber, enlarging the opening that accommodates the largest segment, creating space for the largest segment to move, thereby facilitating fiber opening. In the present invention, the shrinkage of polymer A after boiling water treatment is preferably greater than that of polymer B, with the difference being at least 5%, and more preferably at least 10%.

[0047] In addition to the influence of the shrinkage difference between polymer A and polymer B on the fiber-opening effect of the split-type composite fiber, the affinity between polymer A and polymer B will also affect the fiber-opening effect and spinnability. When the affinity between polymer A and polymer B is good, the fiber-opening of the split-type composite fiber is difficult and the ideal fiber-opening effect cannot be achieved; when the affinity between polymer A and polymer B is too poor, it is easy to produce fuzz during fiber-opening in the melt spinning stage, and the engineering passability is poor, which is not conducive to production. The present invention uses the absolute value of the difference in solubility parameters (SP values) of polymer A and polymer B (hereinafter referred to as the difference in SP values) to characterize the affinity between them. The smaller the difference in SP values, the better the affinity. In order to enable the split-type composite fiber to achieve good fiber-opening effect and spinning performance at the same time, the present invention preferably has a difference in SP values ​​between polymer A and polymer B of 1.0 to 10.8J. 1 / 2 / cm 3 / 2 , more preferably 3.0 to 7.0 J 1 / 2 / cm 3 / 2 .

[0048] The present invention does not particularly limit the specific types of polymer A and polymer B. They may be conventional polymers used for melt spinning, such as polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polypropylene (PP), polyamide-4, polyamide-6, polyamide-56, polyamide-66, polyamide-510, or polyamide-610. Alternatively, the polymers may be functionally modified by adding particles or modifying shrinkage properties, for example, to the above polymers.

[0049] If all other conditions remain the same, too little area occupied by polymer B in the cross-section of the splittable composite fiber will hinder fiber opening; too much area occupied by polymer B will hinder the fluffy and soft feel. Therefore, the area ratio of polymer A to polymer B is preferably between 70:30 and 30:70.

[0050] Unless otherwise specified, the splittable composite fibers described herein can be either long or short fibers. Long fibers can be made into soft-touch clothing or wipes; short fibers can be made into nonwoven fabrics, such as facial masks that retain liquid and conform to the skin. Short fibers ensure minimal initial fiber opening to ensure subsequent processing, while also ensuring sufficient fiber opening even in boiling water. Therefore, short composite fibers are preferred.

[0051] For long fibers, the preferred initial spread ratio of less than 5% can be achieved by essentially meeting the distribution and area requirements for the largest and smallest segments specified in the present invention. However, for short fibers, since the filaments are typically stretched in a warm water bath during the cottonization process, i.e., the cutting of the short fibers, the initial spread ratio is negatively impacted by moisture absorption and swelling, resulting in a higher initial spread ratio for short fibers than for long fibers of the same composition and structure. In considering how to reduce the initial spread ratio of short fibers, the inventors of the present application sought to identify the cause of the fiber spreading during the cutting process and discovered that the primary issue lies in the swelling of polymer A due to water absorption, which creates space for the largest segments to move, causing them to separate from the main structure and increasing the initial spread ratio of the short fibers. By limiting the use of polymer A with low water absorption, the present invention avoids water absorption and swelling of polymer A during the cutting process, achieving a low initial spread ratio for the short fibers. To achieve a low initial spread ratio for the splittable composite short fibers, the present invention preferably employs a water absorption ratio of polymer A below 1.5%.

[0052] For the water absorption rate of the preferred polymer A, a relatively satisfactory fiber opening rate can still be obtained when the fiber is subsequently opened by physical or chemical methods, mainly manifested in that the fiber opening rate after boiling water treatment can reach more than 90%.

[0053] The present invention strictly designs the cross section of the split-type composite fiber, uses a combination of a largest split block and a smaller split block, and limits the size relationship between the largest split block and the smaller split block, so that the initial fiber opening rate of the split-type composite fiber is below 5%, and after being treated with boiling water, it is easy to split, with a fiber opening rate of above 90%, which can meet the needs of various fluffy and soft fiber structures.

[0054] The testing method involved in the present invention is as follows:

[0055] (1) Fiber cross-sectional area (S), largest segment area (S1), and smallest segment area (S2)

[0056] Split composite fibers were wrapped with black or white carded cotton strips and passed through small holes in a copper plate. A blade was used to cut the fibers to obtain a cross-section of the tow. The cross-sections were observed and photographed using a Keyence VHX-6000 ultra-depth 3D fiberscope. Microscope measurement tools were used to measure the fiber cross-sectional area (S), the area of ​​the largest segment (S1), and the area of ​​the smallest segment (S2). The final result was the average of 10 tests.

[0057] (2) Maximum segment perimeter L1 and contact length L2

[0058] Split composite fibers were wrapped with black or white carded cotton strips and passed through small holes in a copper plate. A blade was used to cut the fibers to obtain a tow cross-section. The cross-sections were observed and photographed using a Keyence VHX-6000 ultra-depth 3D fiberscope. Microscope measurement tools were used to measure the perimeter of the largest single segment, L1, and the contact length, L2, between the largest segment and polymer A. The final result was the average of 10 tests.

[0059] (3) The angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section

[0060] Split composite fibers were wrapped with black or white carded cotton strips and passed through small holes in a copper plate. A blade was used to cut the fibers to obtain a cross-section. This cross-section was observed and photographed using a Keyence VHX-6000 ultra-depth 3D fiberscope. Microscope measurement tools were used to measure the angle between the largest split block and the tangent line at the intersection of the fiber cross-section edge. The final result was the average of 10 tests.

[0061] (4) Difference in shrinkage after boiling water treatment

[0062] Take a 20cm (L0) length of split composite fiber and scour it at 40°C (2g / L scouring agent + 0.6% NaOH aqueous solution) to remove contaminants such as fiber surface oil and slurry. After boiling in a 98°C water bath for 20 minutes, remove the fiber and air dry it at 20°C × 65% RH for 4 hours. Use tweezers to separate polymer B from polymer A, and measure the length of polymer B component L3 and the length of polymer A L4 respectively. The difference in shrinkage between polymer A and polymer B after boiling water treatment is [(L3-L4) / L0] × 100%. Take 10 samples for testing and average the final results.

[0063] (5) Solubility parameter (SP value)

[0064] The SP value δp of polymers is measured by turbidity titration. The specific steps are as follows:

[0065] A. After the split composite fiber is opened, polymer A and polymer B are separated using tweezers;

[0066] B. Dissolve 0.5 g of polymer A in 100 ml of solvent (see the table below for the corresponding solvents) to obtain a polymer A solution;

[0067] C. Use a pipette to draw 10 ml of polymer A solution into a test tube. Titrate the solution with n-pentane until a precipitate forms. Shake the tube to dissolve the precipitate. Continue adding n-pentane dropwise until a precipitate that is difficult to dissolve by shaking appears. Record the volume of n-pentane used (V1).

[0068] D. Continue titrating the polymer A solution that precipitated in step C with methanol. The original precipitate will gradually disappear during titration, and new precipitate will appear as methanol is added. Shake the test tube to dissolve the precipitate. Continue adding methanol until a precipitate that is difficult to dissolve by shaking appears. Record the volume of methanol used (V2).

[0069] E. Calculate the solubility parameter of polymer A by the following formula,

[0070] The lower limit of the solubility parameter of polymer A is δml = [V1 / (V1+V2)] × 14.3,

[0071] The upper limit of the solubility parameter of polymer A is δmh = [V1 / (V1+V2)] × 30.2,

[0072] The solubility parameter of polymer A is δp = δmh + δml.

[0073] During the titration in steps C and D above, the amount of liquid dropped by the burette each time was 0.5 ml.

[0074] Take 0.5 g of polymer B and repeat steps B to E to obtain the solubility parameters of polymer B.

[0075] When testing the solubility parameters of polymers A and B, 10 samples were taken for testing respectively, and the final results were averaged.

[0076] (6) Initial fiber opening rate and fiber opening rate after boiling water treatment

[0077] The split composite fiber was cut with a blade to obtain the cross section of the tow, and the fiber was attached to a conductive adhesive and sprayed with gold. The fiber cross section was observed using a Hitachi TM3030plus scanning electron microscope (SEM). 20 samples were taken for testing, and the average value of the final results was used to obtain the initial fiber opening rate.

[0078] The split composite fiber was scoured at 40°C (2g / L scouring agent + 0.6% NaOH aqueous solution) to remove contaminants such as oil and slurry from the fiber surface. The fibers were then boiled in a 98°C water bath for 20 minutes for fiber opening, removed from the fibers, and naturally dried at 20°C × 65% RH for 4 hours. The fibers were then cut with a blade to obtain a tow cross-section. The fibers were then attached to a conductive adhesive and gold-sprayed. The fiber cross-sections were observed using a Hitachi TM3030plus scanning electron microscope (SEM). Twenty samples were tested, and the average of the results was used to determine the fiber opening rate.

[0079] Spreading rate (%) = (number of observed segments / theoretical total number of segments) × 100%,

[0080] In the above formula, the number of observed segments refers to the number of segments that are completely separated from polymer A, and the theoretical total number of segments refers to the number of all segments.

[0081] (7) Water absorption

[0082] After the split composite fiber was opened using the above method, 0.5g of polymer A was separated using tweezers. The polymer was dried in a vacuum oven at 105°C for 8 hours and then conditioned at 20°C and 65% RH for 24 hours. The saturated moisture content of the polymer was then measured using a differential pressure moisture meter. The saturated moisture content, or water absorption rate, was determined. Ten samples were tested for each, and the results were averaged.

[0083] (8) Fluffiness

[0084] The split composite fibers were circular-knitted and scoured at 40°C (2g / L scouring agent + 0.6% NaOH aqueous solution) to remove surface oils, sizing, and other contaminants. The fibers were then opened in a 98°C water bath for 20 minutes and air-dried at 20°C and 65% RH for 4 hours. The fabric's bulk was then evaluated using the KES FB3 method. A higher work-of-compression (WC) value indicates greater compressibility and a fluffier sample.

[0085] The advantages of the present invention will be described in detail below with reference to the following examples and comparative examples. The present invention is not limited to the following examples.

[0086] Example 01:

[0087] Polymer A:PBT (intrinsic viscosity 1.10 dL / g, water absorption 0.4%, SP value 20.5J) with a volume ratio of 70:30 1 / 2 / cm 3 / 2 ) and polymer B: hydrophobically modified PET (polypropylene 2% compound, SP value 19.7J 1 / 2 / cm3 / 2 ) is melt-spinned from spinneret holes on a composite spinneret with 1 large and 16 small sections to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature 278°C for PET, spinning manifold temperature 260°C for PBT, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2250 m / min, and second roller temperature 160°C.

[0088] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11%, S1 / S2 was 9.1 times, L2 / L1 was 62%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 1%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C × 65% RH for 4 hours, the fiber spread was 76%. The difference in boiling water shrinkage between polymer A and polymer B was 11%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.383 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 2%.

[0089] Example 02:

[0090] Polymer A:PBT (intrinsic viscosity 1.10 dL / g, water absorption 0.4%, SP value 20.5J) with a volume ratio of 70:30 1 / 2 / cm 3 / 2 ) and polymer B: hydrophobically modified PET (polypropylene 5% compound, SP value 19.5J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinneret holes on a composite spinneret with 1 large and 16 small sections to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature 278°C for PET, spinning manifold temperature 260°C for PBT, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2250 m / min, and second roller temperature 160°C.

[0091] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11%, S1 / S2 was 9.1 times, L2 / L1 was 62%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 1%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 90%. The difference in boiling water shrinkage between polymer A and polymer B was 11%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.433 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 2%.

[0092] Example 03:

[0093] Polymer A:PBT (intrinsic viscosity 1.10 dL / g, water absorption 0.4%, SP value 20.5J) with a volume ratio of 70:30 1 / 2 / cm 3 / 2 ) and polymer B: PP (MFR 60g / 10min, SP value 16.8J 1 / 2 / cm 3 / 2 ) is melt-spinned from the spinneret holes on a composite spinneret with 1 large and 16 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 260°C, spinning manifold temperature corresponding to PP is 250°C, spinning manifold temperature corresponding to PBT is 260°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 70°C, second roller speed 2250m / min, and second roller temperature 160°C.

[0094] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11%, S1 / S2 was 9.1 times, L2 / L1 was 62%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 3%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 93%. The difference in boiling water shrinkage between polymers A and B was 12%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.485 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 4%.

[0095] Example 04:

[0096] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinnerets with a cross-section of 1 large and 16 small, to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2450 m / min, and second roller temperature 160°C.

[0097] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11%, S1 / S2 was 9.1 times, L2 / L1 was 62%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 3%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 92%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.526 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 12%.

[0098] Example 05:

[0099] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PP (MFR 60g / 10min, SP value 16.8J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 16 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 275°C, spinning manifold temperature corresponding to PP is 250°C, spinning manifold temperature corresponding to N6 is 275°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 70°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0100] On the cross-section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11%, S1 / S2 was 9.1 times, L2 / L1 was 62%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross-section was 90°, the initial fiber spread was 5%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 98%. The difference in boiling water shrinkage between polymers A and B was 11%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.539 gf.cm / cm2. The initial fiber spread of the short fiber prepared from the above-mentioned splittable composite long fiber was 16%.

[0101] Example 06:

[0102] The polymer A:N610 (relative viscosity ηr 2.7, water absorption 1.0%, SP value 27.8J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PP (MFR 60g / 10min, SP value 16.8J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 16 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 275°C, spinning manifold temperature corresponding to PP is 250°C, spinning manifold temperature corresponding to N610 is 275°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 70°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0103] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11%, S1 / S2 was 9.1 times, L2 / L1 was 62%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 7%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 98%. The difference in boiling water shrinkage between polymers A and B was 11%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.527 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 11%.

[0104] Example 07:

[0105] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0106] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 10.0%, S1 / S2 was 2.0 times, L2 / L1 was 58%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 105°, the initial fiber spread was 3%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 95%. The difference in boiling water shrinkage between polymers A and B was 10%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.467 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 16%.

[0107] Example 08:

[0108] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 2 large and 12 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0109] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 9.0%, S1 / S2 was 9.0 times, L2 / L1 was 61%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 91°, the initial fiber spread was 3%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 95%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.488 gf.cm / cm2. The initial fiber spread of the short fiber prepared from the above-mentioned splittable composite long fiber was 12%.

[0110] Example 09:

[0111] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinneret holes on a composite spinneret with 3 large and 6 small sections to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2450 m / min, and second roller temperature 160°C.

[0112] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 7.5%, S1 / S2 was 6.0 times, L2 / L1 was 61%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 91°, the initial fiber spread was 5%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 95%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.463 gf.cm / cm2. The initial fiber spread of the short fiber prepared from the above-mentioned splittable composite long fiber was 15%.

[0113] Comparative Example 01:

[0114] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J1 / 2 / cm 3 / 2 ) was melt-spinned from spinnerets on a composite spinneret with 18 small sections to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process were as follows: a spinning temperature of 278°C, a spinning manifold temperature of 275°C for N6, a spinning manifold temperature of 278°C for PET, a cooling temperature of 20°C, a cooling wind speed of 0.8 m / s, a first roller speed of 1200 m / min, a first roller temperature of 80°C, a second roller speed of 2450 m / min, and a second roller temperature of 160°C.

[0115] On the cross-section of the resulting splittable composite long fiber (56T-18-FDY), the area of ​​a single segment accounted for 1.0% of the fiber's cross-sectional area, the contact length between a single segment and polymer A accounted for 68% of the circumference of the single segment, the angle between the segment and the tangent at the intersection of the segment and the edge of the fiber cross-section was 90°, the initial fiber spread was 2%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 56%. The difference in boiling water shrinkage between polymers A and B was 6%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.319 gf.cm / cm². The initial fiber spread of the short fiber prepared from the above-mentioned splittable composite long fiber was 8%.

[0116] Due to the absence of large split blocks, the fiber opening rate after boiling water treatment is too small.

[0117] Comparative Example 02:

[0118] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 50:50 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 4 large and 8 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0119] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 8.0%, S1 / S2 was 3.6 times, L2 / L1 was 58%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 101°, the initial fiber spread was 13%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 95%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.312 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 15%.

[0120] Since the number of the largest split blocks is too large, the initial fiber opening rates of both long and short fibers are too large.

[0121] Comparative Example 03:

[0122] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with a 1 large and 23 small section, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0123] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 4.0%, S1 / S2 was 3.5 times, L2 / L1 was 63%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 91°, the initial fiber spread was 1%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 63%. The difference in boiling water shrinkage between polymers A and B was 7%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.331 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 9%.

[0124] Since the ratio of the single largest segmented block to the fiber cross-sectional area is too small, it is not conducive to fiber opening, resulting in a too small fiber opening rate after boiling water treatment.

[0125] Comparative Example 04:

[0126] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 25:75 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 3 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0127] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 72.0%, S1 / S2 was 72.0 times, L2 / L1 was 74%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 101°, the initial fiber spread was 2%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 88%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.246 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 9%.

[0128] Since the ratio of a single most segmented block to the fiber cross section is too large, the fabric has poor fluffiness and a poor hand feel after fiber opening.

[0129] Example 10:

[0130] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 50:50 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0131] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), the S1 / S ratio was 17.0%, the S1 / S2 ratio was 2.1, the L2 / L1 ratio was 58%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 106°, the initial fiber spread was 3%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 95%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.451 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 16%.

[0132] Example 11:

[0133] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 30:70 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0134] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 24.0%, S1 / S2 was 2.1 times, L2 / L1 was 68%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 101°, the initial fiber spread was 2%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 92%. The difference in boiling water shrinkage between polymers A and B was 7%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.443 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 17%.

[0135] Example 12:

[0136] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinnerets with a cross-section of 1 large and 16 small, to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2450 m / min, and second roller temperature 160°C.

[0137] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 9.0%, S1 / S2 was 8.1 times, L2 / L1 was 80%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 101°, the initial fiber spread was 1%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 75%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.482 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 8%.

[0138] Example 13:

[0139] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 50:50 was prepared. 1 / 2 / cm 3 / 2) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0140] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 18.0%, S1 / S2 was 2.3 times, L2 / L1 was 74%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 73°, the initial fiber spread was 1%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 58%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.379 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 6%.

[0141] Example 14:

[0142] The polymer A:N6 (relative viscosity ηr of 3.2, water absorption rate of 3.4%, SP value of 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinnerets with a cross-section of 1 large and 16 small, to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2450 m / min, and second roller temperature 160°C.

[0143] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11.0%, S1 / S2 was 9.1 times, L2 / L1 was 63%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 2%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 98%. The difference in boiling water shrinkage between polymers A and B was 15%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.532 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 12%.

[0144] Example 15:

[0145] The polymer A:N610 (relative viscosity ηr 2.7, water absorption 1.5%, SP value 27.8J) with a volume ratio of 50:50 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinneret holes on a composite spinneret with 1 large and 4 small sections to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature 275°C for N610, spinning manifold temperature 278°C for PET, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2450 m / min, and second roller temperature 160°C.

[0146] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 17.0%, S1 / S2 was 2.1 times, L2 / L1 was 58%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 106°, the initial fiber spread was 0%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 95%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.487 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 5%.

[0147] Example 16:

[0148] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 50:50 was prepared. 1 / 2 / cm 3 / 2) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0149] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 18.0%, S1 / S2 was 2.3 times, L2 / L1 was 45%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 126°, the initial fiber spread was 5%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 97%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.489 gf.cm / cm2. The initial fiber spread of the short fiber prepared from the above-mentioned splittable composite long fiber was 12%.

[0150] Example 17:

[0151] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 50:50 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0152] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 18.0%, S1 / S2 was 2.3 times, L2 / L1 was 40%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 135°, the initial fiber spread was 7%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 97%. The difference in boiling water shrinkage between polymers A and B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.474 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 16%.

[0153] Example 18:

[0154] The polymer A:N6 (relative viscosity ηr of 2.4, water absorption rate of 3.4%, SP value of 27.6J) with a volume ratio of 70:30 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned from spinnerets with a cross-section of 1 large and 16 small, to produce FDY filaments according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8 m / s, first roller speed 1200 m / min, first roller temperature 80°C, second roller speed 2450 m / min, and second roller temperature 160°C.

[0155] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 11.0%, S1 / S2 was 9.1 times, L2 / L1 was 63%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 90°, the initial fiber spread was 2%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 81%. The difference in boiling water shrinkage between polymers A and B was 4%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.485 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 8%.

[0156] Example 19:

[0157] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 25:75 was prepared. 1 / 2 / cm 3 / 2) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 3 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0158] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 70.0%, S1 / S2 was 42.0 times, L2 / L1 was 73%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 101°, the initial fiber spread was 2%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 90%. The difference in boiling water shrinkage between polymer A and polymer B was 8%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.253 gf.cm / cm2. The initial fiber spread of the short fiber obtained from the above-mentioned splittable composite long fiber was 9%.

[0159] Example 20:

[0160] The polymer A:N6 (relative viscosity ηr 2.9, water absorption 3.3%, SP value 27.6J) with a volume ratio of 80:20 was prepared. 1 / 2 / cm 3 / 2 ) and polymer B: PET (intrinsic viscosity 0.61dL / g, SP value 21.0J 1 / 2 / cm 3 / 2 ) is melt-spinned and discharged from the spinneret holes on a composite spinneret with 1 large and 4 small sections, and FDY filaments are obtained according to the FDY process, wherein other parameters of the FDY process are: spinning temperature 278°C, spinning manifold temperature corresponding to N6 is 275°C, spinning manifold temperature corresponding to PET is 278°C, cooling temperature 20°C, cooling wind speed 0.8m / s, first roller speed 1200m / min, first roller temperature 80°C, second roller speed 2450m / min, and second roller temperature 160°C.

[0161] On the cross section of the resulting splittable composite long fiber (56T-18-FDY), S1 / S was 8.0%, S1 / S2 was 2.6 times, L2 / L1 was 56%, the angle between the tangent line at the intersection of the largest segment and the edge of the fiber cross section was 102°, the initial fiber spread was 3%, and after heat treatment in a 98°C water bath for 20 minutes and natural drying at 20°C x 65% RH for 4 hours, the fiber spread was 90%. The difference in boiling water shrinkage between polymers A and B was 7%, and the compression work ratio of the circular knitted fabric after fiber spreading was 0.448 gf.cm / cm2. The initial fiber spread of the short fiber prepared from the above-mentioned splittable composite long fiber was 16%.

[0162] Table 1

[0163] Table 2

[0164] Table 3

[0165] Table 4

Claims

1. A split composite fiber, comprising a polymer A and a polymer B, wherein the polymer A is continuously distributed on the fiber cross section, and the polymer B is divided into large split blocks and small split blocks, and all the split blocks are exposed on the fiber surface; characterized in that: The single fiber cross section has 1 to 3 largest blocks with the same area, and more than 2 small blocks with smaller areas than the largest block; the area of ​​the single largest block accounts for 7.5 to 70.0% of the fiber cross section area, and the area of ​​the single largest block is more than twice the area of ​​the single small block.

2. The split-type composite fiber according to claim 1, characterized in that: The perimeter of the single largest segment is L1, the contact length between the single largest segment and polymer A is L2, and L2 / L1 is 45-80%.

3. The split-type composite fiber according to claim 1 or 2, characterized in that: The angle between the tangent line at the intersection of the largest segmented block and the edge of the fiber cross section is greater than 90°.

4. The split-type composite fiber according to claim 1 or 2, characterized in that: After the composite fiber is treated with boiling water, the shrinkage rate of polymer A is greater than that of polymer B, and the difference is more than 5%.

5. The split-type composite fiber according to claim 1 or 2, characterized in that: The difference in solubility parameters between polymer A and polymer B is 1.0 to 10.8 J 1 / 2 / cm 3 / 2 .

6. The split-type composite fiber according to claim 1 or 2, characterized in that: The polymer A and polymer B are polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene, polyamide-4, polyamide-6, polyamide-56, polyamide-66, polyamide-510 or polyamide-610 respectively.

7. The split-type composite fiber according to claim 1 or 2, characterized in that: The area ratio of polymer A to polymer B on the cross section of the composite fiber is 70:30 to 30:

70.

8. The split-type composite fiber according to claim 1 or 2, characterized in that: The initial fiber opening rate of the composite fiber is below 5%, and the fiber opening rate after being treated with boiling water is above 90%.

9. The split-type composite fiber according to claim 1 or 2, characterized in that: The composite fiber is a short fiber, and the initial fiber opening rate is below 5%.

10. The split-type composite fiber according to claim 9, characterized in that: The water absorption rate of the polymer A is below 1.5%.

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