Preparation method and application of polyethylene / polyester composite fiber

Abstract

The invention discloses a preparation method and application of a polyethylene / polyester composite fiber, belongs to the technical field of composite fibers, solves the problems of poor compatibility, easy separation of skin and core and poor mechanical property in the prior art, and comprises the following steps: preparing the polyethylene / polyester composite fiber from a skin layer raw material and a core layer raw material according to a skin-core composite spinning process; the raw material of the skin layer is polyethylene, the raw material of the core layer is a blend of polyester and a compatilizer, the compatilizer is a polyethylene and poly (ethylene-co-glycidyl methacrylate) grafted copolymer, and the polyethylene / polyester composite fiber flocculus is prepared from polyethylene / polyester composite fibers through carding web forming, hot drying and sizing treatment. The surface density of the polyethylene / polyester composite fiber flocculus is 17.8 g / m < 2 >, the transverse breaking strength is 5.0-5.6 N, and the longitudinal breaking strength is 30.7-35.3 N. The preparation method provided by the invention can effectively reduce the phenomena of skin-core separation, slippage and the like of the polyethylene / polyester composite fiber, and the composite fiber flocculus prepared from the polyethylene / polyester composite fiber has excellent mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of composite fibers and relates to a preparation method and application of polyethylene / polyester composite fibers. Background Art

[0002] PE (polyethylene) / PET (polyethylene terephthalate) hot melt fiber is a bicomponent fiber made by skin-core composite spinning. PET as the core material is cheap and easy to source, and has a greater cost advantage than other fiber materials. PE with a low melting point is used as the skin component, and the core layer is PET with a higher melting point. Through the unique production process of hot air bonding, the hot air nonwoven fabric produced is safe and non-toxic, fluffy and has good permeability, and can be widely used in the medical and health fields.

[0003] Hot air bonding gives sanitary materials excellent fluffiness, air permeability and high liquid conductivity through point bonding of fibers. Conventional core-skin composite fibers, due to the affinity of the core-skin layer materials, adopt a parallel and eccentric spinning method, using the difference in melting points and stress imbalance of the two materials, and obtain the curl and fluffiness of the fiber after stretching. However, due to the poor compatibility of PET and PE, the processing technology of composite fibers is complicated. When the cross-section is a parallel or eccentric structure, it is easy to cause skin-core separation, slippage and other phenomena, affecting the subsequent processing technology and the comfort of the fabric layer of the terminal sanitary product.

[0004] However, existing PE / PET composite materials generally have problems such as poor compatibility and poor strength, which causes the skin-core fiber to slip and separate during the subsequent multi-pass stretching of spinning. Invention patent CN201910517649.3 discloses a method of making it difficult for the skin and core of two-component fibers to separate by changing the process. The PE / PET molten base is injection molded into a hollow concentric circle structure, and the PE is tightly coated on the PET surface skin core in the outer layer, resulting in low mechanical properties of the fiber, increased hair during production, and poor longitudinal and transverse mechanical properties of PE / PET fiber fabrics.

[0005] Therefore, it is of practical significance to reduce the skin-core separation and slippage of PE / PET composite fibers and improve the mechanical properties of composite fibers. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a preparation method and application of polyethylene / polyester composite fibers.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a polyethylene / polyester composite fiber comprises the following steps: (1) Preparation of compatibilizer; The polyethylene and poly(ethylene-co-glycidyl methacrylate) (EGMA) are dried separately, added into an internal mixer, and granulated to obtain the compatibilizer; (2) Spinning; The dried polyethylene in S1 is melted by the screw, and the measured polyethylene melt enters the spinning box A; S2 The dried polyester is mixed with the compatibilizer and then melted and exhausted by the screw in sequence, and the metered mixed melt enters the spinning box B; S3: The melt in the spinning beam A and the spinning beam B is ejected through the composite spinneret to form a sheath-core structured filament, which is then spun, cooled, bundled, stretched, curled, cut, and dried to obtain polyethylene / polyester composite fibers; The raw material of the skin layer is polyethylene (PE), and the raw material of the core layer is a blend of polyester (PET) and a compatibilizer; The compatibilizer is polyethylene and poly (ethylene-co-glycidyl methacrylate) graft copolymer (PE-EGMA).

[0008] As the preferred technical solution: A method for preparing a polyethylene / polyester composite fiber as described above, wherein the polyethylene / polyester composite fiber has a single fiber fineness of 1.8~2.2dtex, a breaking strength of 2.8~3.3cN / dtex, an elongation at break of 60.0±20.0%, a curl number of 13~17 / 25mm, a curl degree of 15~20%, and a fiber length of 35~40mm.

[0009] In the method for preparing the polyethylene / polyester composite fiber as described above, the weight ratio of the skin layer raw material to the core layer raw material is 40-50:50-60.

[0010] The method for preparing a polyethylene / polyester composite fiber as described above, wherein the polyethylene is heated at a temperature of 190°C and a pressure of 0.3MPa (3 kgf / cm2). 2 ) is 20±2 g / 10 min, and the intrinsic viscosity of the polyester is 0.65~0.68 dL / g.

[0011] In the method for preparing a polyethylene / polyester composite fiber as described above, in step (1), the temperature of the internal mixer is 180-190° C., the rotation speed is 50-60 rpm, and the internal mixing time is 10-15 min.

[0012] In the method for preparing a polyethylene / polyester composite fiber as described above, in step (1), the mass ratio of polyethylene to poly(ethylene-co-glycidyl methacrylate) is 100:3-5.

[0013] In the method for preparing a polyethylene / polyester composite fiber as described above, in step S1, the screw melting temperature is 220-250° C., and the polyethylene melt conveying temperature is 260-265° C.; In step S2, the screw melting temperature is 270-280°C, and the mixed melt conveying temperature is 280-285°C; In step S3, the spinning temperature is 280-285°C, and the spinning speed is 1000-1200 m / min; the cooling adopts ring air cooling, the ring air temperature is 14-18°C, and the ring air speed is 1.0-1.2 m / s; the first stretching temperature is 70-75°C, the second stretching temperature is 100°C, and the total stretching multiple is 2.8-3.2 times; the drying temperature is 100-110°C.

[0014] In the method for preparing a polyethylene / polyester composite fiber as described above, the mass ratio of polyester to compatibilizer in step S2 is 100:2-3.

[0015] The present invention also provides an application of the polyethylene / polyester composite fiber prepared by the method described in any one of the above, wherein the polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare a polyethylene / polyester composite fiber flake; The surface density of the polyethylene / polyester composite fiber flakes is 17.8 g / m 2 The transverse breaking strength is 5.0~5.6N, and the longitudinal breaking strength is 30.7~35.3N; in the prior art, the longitudinal breaking strength of the polyethylene / polyester composite fiber flakes is 23.3~30.2N, and the transverse breaking strength is 3.8~4.7N.

[0016] Invention mechanism: In the prior art PE / PET sheath-core fiber, the compatibility between the PE in the sheath layer and the PET in the core layer is poor, which causes the sheath fiber and the core fiber to easily fall off during stretching, and the longitudinal and transverse tensile strength of the PE / PET fabric is relatively low.

[0017] In view of this technical problem, the present invention aims to provide a PE / PET fiber with good compatibility, in which a PE graft copolymer is added to the PET in the core layer of the PE / PET fiber as a compatibilizer, and the compatibilizer is formed by grafting polyethylene with poly(ethylene-co-glycidyl methacrylate).

[0018] The glycidyl methacrylate molecule in the compatibilizer contains two hydroxyl groups, which can form ether bonds with the terminal hydroxyl groups of PET and react with the terminal carboxyl groups to form esters.

[0019] Due to the certain viscosity difference between PET and the compatibilizer, the low-viscosity component compatibilizer migrates from the central low shear rate zone to the outer high shear rate zone and gathers outside the core polyester fiber. On the one hand, the compatibility of the compatibilizer with the polar polyester is improved due to the introduction of polar groups, thereby enhancing the interaction between the compatibilizer and the polyester; on the other hand, since the compatibilizer is gathered outside the core polyester fiber and preferentially distributed at the interface between the two phases, the poly (ethylene-co-glycidyl methacrylate) in the compatibilizer reduces the interfacial tension between PET and PE, can appropriately improve the interfacial adhesion between PET and PE, reduce the interfacial energy between PET and PE, and increase the compatibility between PET and PE; the polyolefin part in the compatibilizer is similarly compatible with the polyethylene of the skin layer, and the compatibilizer increases the tightness of the core layer PET and the skin layer PE, connects the PET and PE macromolecular chains, and improves the compatibility of the two materials, thereby increasing the interaction between the skin layer and the core layer, strengthening the bonding force between the skin and core layers, and effectively improving the component incompatibility phenomena such as the slippage of the skin-core fibers, thereby solving the problems of skin-core separation and poor strength caused by poor compatibility. Beneficial Effects

[0020] (1) In a method for preparing a polyethylene / polyester composite fiber of the present invention, the glycidyl methacrylate molecule used in the compatibilizer contains two hydroxyl groups, which can form an ether bond with the terminal hydroxyl group of PET and react with the terminal carboxyl group to form an ester. The compatibility of the compatibilizer with the polar polyester is improved due to the introduction of polar groups, thereby enhancing the interaction between the compatibilizer and the polyester. (2) In the method for preparing a polyethylene / polyester composite fiber of the present invention, the compatibilizer used reduces the interfacial tension between PET and PE, can appropriately improve the interfacial adhesion between PET and PE, increase the tightness of the core layer PET and the skin layer PE, connect the macromolecular chains of PET and PE, improve the compatibility of the two materials, thereby increasing the interaction force between the skin layer and the core layer, and solving the problems of skin-core layer separation and poor strength caused by poor compatibility; (3) The polyethylene / polyester composite fiber of the present invention is used to prepare polyethylene / polyester composite fiber flakes, and the prepared polyethylene / polyester composite fiber flakes have excellent mechanical properties. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0022] Among the raw materials used in the embodiments of the present invention, the melt index of polyethylene is 20 g / 10 min (test conditions: temperature 190° C., pressure 0.3 MPa), and the intrinsic viscosity of polyester is 0.67 dL / g. Example

[0023] A method for preparing a polyethylene / polyester composite fiber, the specific steps are as follows: (1) Preparation of compatibilizer; After polyethylene and poly(ethylene-co-glycidyl methacrylate) are dried separately, they are added into an internal mixer at a mass ratio of 100:3, and granulated by internal mixing to obtain a polyethylene and poly(ethylene-co-glycidyl methacrylate) graft copolymer, i.e., a compatibilizer; wherein the temperature of the internal mixer is 180° C., the speed is 50 rpm, and the mixing time is 15 min; (2) Spinning; The polyethylene after S1 drying is melted by the screw, and the measured polyethylene melt enters the spinning box A; wherein the screw melting temperature is 220°C, and the polyethylene melt conveying temperature is 260°C; The dried polyester and the compatibilizer in S2 are mixed in a mass ratio of 100:2, and then melted and exhausted by the screw in sequence. The metered mixed melt enters the spinning box B; wherein the screw melting temperature is 270°C, and the mixed melt conveying temperature is 280°C; The melt in S3 spinning box A and spinning box B is ejected through the composite spinneret in a mass ratio of 40:60 to form filaments with a skin-core structure, and then successively spun, cooled, bundled, stretched, curled, cut and dried to obtain polyethylene / polyester composite fibers; wherein, the spinning temperature is 280°C and the spinning speed is 1000m / min; cooling is carried out by ring air cooling, the ring air temperature is 18°C, and the ring air speed is 1.0m / s; the first stretching temperature is 70°C, the second stretching temperature is 100°C, and the total stretching multiple is 3.2 times; the drying temperature is 100°C.

[0024] The single fiber fineness of the prepared polyethylene / polyester composite fiber is 2.2 dtex, the breaking strength is 3.1 cN / dtex, the breaking elongation is 70%, the number of crimps is 13 / 25mm, the crimp degree is 18%, and the fiber length is 35 mm.

[0025] The polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare polyethylene / polyester composite fiber flakes. The heat-dried temperature is 150°C. The shaping temperature is: 155°C for the upper roller and 165°C for the lower roller. The surface density of the polyethylene / polyester composite fiber flakes is 17.8 g / m 2 The transverse breaking strength is 5.1N and the longitudinal breaking strength is 30.7N. Example

[0026] A method for preparing a polyethylene / polyester composite fiber, the specific steps are as follows: (1) Preparation of compatibilizer; After polyethylene and poly(ethylene-co-glycidyl methacrylate) are dried separately, they are added into an internal mixer at a mass ratio of 100:3, and granulated by internal mixing to obtain a polyethylene and poly(ethylene-co-glycidyl methacrylate) graft copolymer, i.e., a compatibilizer; wherein the temperature of the internal mixer is 180° C., the speed is 50 rpm, and the mixing time is 15 min; (2) Spinning; The polyethylene after S1 drying is melted by the screw, and the measured polyethylene melt enters the spinning box A; wherein the screw melting temperature is 225°C, and the polyethylene melt conveying temperature is 262°C; The dried polyester and the compatibilizer in S2 are mixed in a mass ratio of 100:2.2, and then melted and exhausted by the screw in sequence. The metered mixed melt enters the spinning box B; wherein the screw melting temperature is 275°C, and the mixed melt conveying temperature is 282°C; The melt in S3 spinning box A and spinning box B is ejected through the composite spinneret in a mass ratio of 50:50 to form filaments with a skin-core structure, and then successively spun, cooled, bundled, stretched, curled, cut and dried to obtain polyethylene / polyester composite fibers; wherein, the spinning temperature is 282°C and the spinning speed is 1100m / min; cooling is carried out by ring air cooling, the ring air temperature is 15°C, and the ring air speed is 1.1m / s; the first stretching temperature is 73°C, the second stretching temperature is 100°C, and the total stretching multiple is 3.0 times; the drying temperature is 110°C.

[0027] The obtained polyethylene / polyester composite fiber has a single filament fineness of 2.0 dtex, a breaking strength of 3.2 cN / dtex, a breaking elongation of 50%, a crimp number of 15 / 25 mm, a crimp degree of 15%, and a fiber length of 40 mm.

[0028] The polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare polyethylene / polyester composite fiber flakes. The heat-dried temperature is 152°C. The shaping temperature is: 157°C for the upper roller and 168°C for the lower roller. The surface density of the polyethylene / polyester composite fiber flakes is 17.8 g / m 2 The transverse breaking strength is 5.6N and the longitudinal breaking strength is 35.3N. Example

[0029] A method for preparing a polyethylene / polyester composite fiber, the specific steps are as follows: (1) Preparation of compatibilizer; After polyethylene and poly(ethylene-co-glycidyl methacrylate) were dried separately, they were added into an internal mixer at a mass ratio of 100:3.5, and granulated by internal mixing to obtain a polyethylene and poly(ethylene-co-glycidyl methacrylate) graft copolymer, i.e., a compatibilizer; wherein the temperature of the internal mixer was 182° C., the speed was 55 rpm, and the internal mixing time was 12 min; (2) Spinning; The polyethylene after S1 drying is melted by the screw, and the measured polyethylene melt enters the spinning box A; wherein the screw melting temperature is 230°C, and the polyethylene melt conveying temperature is 265°C; The dried polyester and the compatibilizer in S2 are mixed in a mass ratio of 100:2.5, and then melted and exhausted by the screw in sequence. The metered mixed melt enters the spinning box B; wherein the screw melting temperature is 278°C, and the mixed melt conveying temperature is 285°C; The melt in S3 spinning box A and spinning box B is ejected through the composite spinneret in a mass ratio of 50:50 to form filaments with a skin-core structure, and then successively spun, cooled, bundled, stretched, curled, cut and dried to obtain polyethylene / polyester composite fibers; wherein, the spinning temperature is 283°C and the spinning speed is 1150m / min; cooling is carried out by ring air cooling, the ring air temperature is 16°C, and the ring air speed is 1.2m / s; the first stretching temperature is 71°C, the second stretching temperature is 100°C, and the total stretching multiple is 2.9 times; the drying temperature is 120°C.

[0030] The obtained polyethylene / polyester composite fiber has a single filament fineness of 1.9 dtex, a breaking strength of 2.9 cN / dtex, a breaking elongation of 60%, a crimp number of 17 / 25mm, a crimp degree of 18%, and a fiber length of 38 mm.

[0031] The polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare polyethylene / polyester composite fiber flakes. The heat-dried temperature is 155°C. The shaping temperature is: 160°C for the upper roller and 170°C for the lower roller. The surface density of the polyethylene / polyester composite fiber flakes is 17.8 g / m 2 The transverse breaking strength is 5.0N and the longitudinal breaking strength is 33.6N. Example

[0032] A method for preparing a polyethylene / polyester composite fiber, the specific steps are as follows: (1) Preparation of compatibilizer; After polyethylene and poly(ethylene-co-glycidyl methacrylate) are dried separately, they are added into an internal mixer at a mass ratio of 100:4, and granulated by internal mixing to obtain a polyethylene and poly(ethylene-co-glycidyl methacrylate) graft copolymer, i.e., a compatibilizer; wherein the temperature of the internal mixer is 186° C., the speed is 60 rpm, and the internal mixing time is 10 min; (2) Spinning; The polyethylene after S1 drying is melted by the screw, and the measured polyethylene melt enters the spinning box A; wherein the screw melting temperature is 240°C, and the polyethylene melt conveying temperature is 265°C; The dried polyester and the compatibilizer in S2 are mixed in a mass ratio of 100:3, and then melted and exhausted by the screw in sequence. The metered mixed melt enters the spinning box B; wherein the screw melting temperature is 280°C, and the mixed melt conveying temperature is 285°C; The melt in S3 spinning box A and spinning box B is ejected through the composite spinneret in a mass ratio of 50:50 to form filaments with a skin-core structure, and then successively spun, cooled, bundled, stretched, curled, cut and dried to obtain polyethylene / polyester composite fibers; wherein, the spinning temperature is 285°C and the spinning speed is 1200m / min; cooling is carried out by ring air cooling, the ring air temperature is 15°C, and the ring air speed is 1.2m / s; the first stretching temperature is 75°C, the second stretching temperature is 100°C, and the total stretching multiple is 3.1 times; the drying temperature is 120°C.

[0033] The single fiber fineness of the polyethylene / polyester composite fiber obtained is 1.8 dtex, the breaking strength is 3.3 cN / dtex, the breaking elongation is 40%, the number of crimps is 16 / 25mm, the crimp degree is 20%, and the fiber length is 38 mm.

[0034] The polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare polyethylene / polyester composite fiber flakes. The heat-dried temperature is 155°C. The shaping temperature is: 165°C for the upper roller and 175°C for the lower roller. The surface density of the polyethylene / polyester composite fiber flakes is 17.8 g / m 2 The transverse breaking strength is 5.5N and the longitudinal breaking strength is 35.0N. Example

[0035] A method for preparing a polyethylene / polyester composite fiber, the specific steps are as follows: (1) Preparation of compatibilizer; After polyethylene and poly(ethylene-co-glycidyl methacrylate) were dried separately, they were added into an internal mixer at a mass ratio of 100:5, and granulated by internal mixing to obtain a polyethylene and poly(ethylene-co-glycidyl methacrylate) graft copolymer, i.e., a compatibilizer; wherein the temperature of the internal mixer was 190°C, the speed was 60rpm, and the mixing time was 10min; (2) Spinning; The polyethylene after S1 drying is melted by the screw, and the measured polyethylene melt enters the spinning box A; wherein the screw melting temperature is 250°C, and the polyethylene melt conveying temperature is 265°C; The dried polyester and the compatibilizer in S2 are mixed in a mass ratio of 100:3, and then melted and exhausted by the screw in sequence. The metered mixed melt enters the spinning box B; wherein the screw melting temperature is 280°C, and the mixed melt conveying temperature is 285°C; The melt in S3 spinning box A and spinning box B is ejected through the composite spinneret in a mass ratio of 60:40 to form filaments with a skin-core structure, and then successively spun, cooled, bundled, stretched, curled, cut and dried to obtain polyethylene / polyester composite fibers; wherein, the spinning temperature is 285°C and the spinning speed is 1200m / min; cooling is carried out by ring air cooling, the ring air temperature is 14°C, and the ring air speed is 1.2m / s; the first stretching temperature is 75°C, the second stretching temperature is 100°C, and the total stretching multiple is 2.8 times; the drying temperature is 120°C.

[0036] The single fiber fineness of the prepared polyethylene / polyester composite fiber is 2.1 dtex, the breaking strength is 2.8 cN / dtex, the breaking elongation is 80%, the number of crimps is 17 / 25mm, the crimp degree is 20%, and the fiber length is 38 mm.

[0037] The polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare polyethylene / polyester composite fiber flakes. The heat-dried temperature is 155°C. The shaping temperature is: 165°C for the upper roller and 175°C for the lower roller. The surface density of the polyethylene / polyester composite fiber flakes is 17.8 g / m 2 The transverse breaking strength is 5.0N and the longitudinal breaking strength is 31.0N.

Claims

1. A method for preparing a polyethylene / polyester composite fiber, characterized in that: The steps include: (1) Preparation of compatibilizer; The polyethylene and poly(ethylene-co-glycidyl methacrylate) are dried separately, added into an internal mixer, and granulated to obtain the compatibilizer; (2) Spinning; The dried polyethylene in S1 is melted by the screw, and the measured polyethylene melt enters the spinning box A; S2 The dried polyester is mixed with the compatibilizer and then melted and exhausted by the screw in sequence, and the metered mixed melt enters the spinning box B; S3: The melt in the spinning beam A and the spinning beam B is ejected through the composite spinneret to form a sheath-core structured filament, which is then spun, cooled, bundled, stretched, curled, cut, and dried to obtain polyethylene / polyester composite fibers; The raw material of the skin layer is polyethylene, the raw material of the core layer is a blend of polyester and a compatibilizer, and the compatibilizer is a polyethylene and poly (ethylene-co-glycidyl methacrylate) graft copolymer.

2. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: The polyethylene / polyester composite fiber has a single filament fineness of 1.8-2.2 dtex, a breaking strength of 2.8-3.3 cN / dtex, a breaking elongation of 60.0±20.0%, a crimp number of 13-17 / 25 mm, a crimp degree of 15-20%, and a fiber length of 35-40 mm.

3. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: The weight ratio of the skin layer raw material to the core layer raw material is 40~50:50~60.

4. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: The melt index of the polyethylene measured at a temperature of 190° C. and a pressure of 0.3 MPa is 20±2 g / 10 min, and the intrinsic viscosity of the polyester is 0.65-0.68 dL / g.

5. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: In step (1), the temperature of the internal mixer is 180-190° C., the rotation speed is 50-60 rpm, and the internal mixing time is 10-15 min.

6. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: In step (1), the mass ratio of polyethylene to poly(ethylene-co-glycidyl methacrylate) is 100:3-5.

7. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: In step S1, the screw melting temperature is 220-250° C., the polyethylene melt conveying temperature is 260-265° C., in step S2, the screw melting temperature is 270-280° C., the mixed melt conveying temperature is 280-285° C., in step S3, the spinning temperature is 280-285° C., and the spinning speed is 1000-1200 m / min; cooling adopts ring air cooling, the ring air temperature is 14-18° C., the ring air speed is 1.0-1.2 m / s, the first stretching temperature is 70-75° C., the second stretching temperature is 100° C., the total stretching multiple is 2.8-3.2 times, and the drying temperature is 100-110° C.

8. The method for preparing a polyethylene / polyester composite fiber according to claim 1, characterized in that: In step S2, the mass ratio of polyester to compatibilizer is 100:2-3.

9. Application of the polyethylene / polyester composite fiber prepared by the method according to any one of claims 1 to 8, characterized in that: The polyethylene / polyester composite fiber is carded into a web, heat-dried and shaped to prepare a polyethylene / polyester composite fiber flake, wherein the surface density of the polyethylene / polyester composite fiber flake is 17.8 g / m 2 The transverse breaking strength is 5.0~5.6N, and the longitudinal breaking strength is 30.7~35.3N.