A stretchable elastic false eyelash

Abstract

The present application relates to the technical field of false eyelashes, and particularly discloses stretchable elastic false eyelashes, which comprise an elastic eyelash base strip and a plurality of eyelash filaments arranged on the elastic eyelash base strip, the roots of the plurality of eyelash filaments are sequentially arranged and fixed along the length direction of the elastic eyelash base strip, each of the eyelash filaments is composed of a core-sheath composite structure of a TPU elastic core filament and a matte PBT setting layer wrapped outside the TPU elastic core filament, and the TPU elastic core filament is used to stretch and deform when the eyelash filament is subjected to axial tension and to drive the eyelash filament to rebound and reset after the tension is removed, wherein the stretchable elastic false eyelashes can adapt to different eye contours and dynamic changes of the eyes through the arrangement of the elastic eyelash base strip, the TPU elastic core filament, the matte PBT setting layer and the micro telescopic control groove, the adaptability and wearing comfort of the false eyelashes to various eye types are improved, the wearing is more comfortable, the makeup is more durable, and the service life of the product is longer.

Description

Technical Field

[0001] This invention relates to the field of false eyelash technology, specifically to a stretchable elastic false eyelash. Background Technology

[0002] False eyelashes are a type of beauty product used to beautify the eyes and enhance their three-dimensionality. They typically consist of an eyelash base strip and several eyelash strands glued to the base strip. When used, the eyelash base strip is attached to the edge of the eyelid, allowing the eyelash strands to work in conjunction with the natural eyelashes to visually increase the density and length of the eyelashes. Currently, most false eyelashes on the market use PBT or PET fibers for the eyelash strands, while the eyelash base strip is usually made of cotton thread or transparent plastic. The overall curl of the false eyelashes relies on the toughness of the fibers themselves.

[0003] However, the aforementioned PBT or PET fibers are rigid, non-stretchable materials. The eyelash strands made from them only have toughness but no elasticity. When the human eye blinks frequently and the face moves, the eyelash strands cannot stretch or contract accordingly, directly pulling on the original eyelashes, causing eye irritation, eyelid stinging, and a foreign body sensation. Long-term wear can also lead to the loss of the original eyelashes. At the same time, the eyelash strands have no resilience, and after wearing them for a few hours, they will collapse and lose their curl, making it difficult for the makeup effect to last. They are also prone to breakage during stretching, storage, and makeup removal, and are easily brittle in low-temperature environments, resulting in a short lifespan. In addition, the existing eyelash base strips also lack the ability to stretch and rebound, and cannot adapt to different eye shapes and dynamic eye deformations. They have poor fit and are prone to problems such as curling, shifting, and falling off. Therefore, a stretchable elastic false eyelash is proposed to address the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a stretchable elastic false eyelash to solve the problems that existing false eyelashes do not have the ability to stretch and rebound, resulting in pulling on the original eyelashes, easy collapse and deformation, poor fit and short service life when worn.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A stretchable elastic false eyelash includes an elastic eyelash base strip and a plurality of eyelash strands implanted on the elastic eyelash base strip. The roots of the plurality of eyelash strands are arranged sequentially and fixed along the length direction of the elastic eyelash base strip. Each eyelash strand consists of a core-sheath composite structure composed of a TPU elastic core strand and a matte PBT shaping layer covering the outside of the TPU elastic core strand. The TPU elastic core strand is used to stretch and deform the eyelash strand when subjected to axial tension and to cause the eyelash strand to spring back to its original position after the tension is removed. The matte PBT shaping layer is used to maintain the stiff and curled shape of the eyelash strand and limit its maximum stretch. The outer wall of the matte PBT shaping layer has openings... A plurality of micro-telescopic control grooves are arranged equidistantly along the axis. Each micro-telescopic control groove is a circumferential narrow slit-shaped groove that surrounds the eyelash. When the eyelash is not stretched, the two side walls of the groove openings of the micro-telescopic control grooves are in contact. When the eyelash is subjected to axial stretching, the openings of each micro-telescopic control groove open synchronously to disperse the stretching amount of the eyelash. The elastic eyelash base strip includes WPU elastic transparent yarn attached to the roots of a plurality of eyelashes and a transparent adhesive layer that bonds and fixes the WPU elastic transparent yarn to the roots of a plurality of eyelashes. The elastic eyelash base strip has full-area stretching and rebound capability and can stretch and automatically rebound along the overall eye contour.

[0006] Preferably, the depth of the micro-telescopic control groove is smaller than the wall thickness of the matte PBT molding layer, and the edges of the micro-telescopic control groove are all rounded.

[0007] Preferably, the radial thickness ratio of the TPU elastic core filament to the matte PBT shaping layer is 1:2.5, and the roots of several eyelashes are inserted into the transparent adhesive layer to a depth of 0.02~0.05mm.

[0008] Preferably, the raw materials of the TPU elastic core yarn include 90 parts of thermoplastic polyurethane (TPU), 8 parts of elastic toughening agent, and 2 parts of anti-yellowing agent by weight. The elastic toughening agent is used to improve the repeated stretching resistance of the TPU elastic core yarn and prevent the eyelash yarn from loosening or breaking after repeated stretching. The anti-yellowing agent is used to inhibit the yellowing and aging of the TPU elastic core yarn under long-term use and contact with makeup remover and sweat, and ensure the long-term stability of the elastic performance of the eyelash yarn.

[0009] Preferably, the raw materials of the matte PBT shaping layer include 68 parts of flexible PBT, 12 parts of silicone micro powder, 18 parts of TPE elastomer, and 2 parts of smoothing agent by weight. The silicone micro powder is used to give the outer wall of the matte PBT shaping layer a matte texture, making the appearance of the eyelashes closer to real eyelashes. The TPE elastomer is used to improve the flexibility of the matte PBT shaping layer, so that the matte PBT shaping layer can stretch and rebound synchronously with the TPU elastic core without cracking. The smoothing agent is used to improve the surface smoothness of the outer wall of the matte PBT shaping layer and reduce the foreign object feeling when touching the groove of the micro-telescopic control groove.

[0010] Preferably, a preparation method includes the following steps: S1. Batching and Plasticizing: Prepare core layer raw materials and sheath layer raw materials according to the mass parts. After mixing the two raw materials separately, send them to two extruders for melt plasticizing to obtain core layer melt and sheath layer melt. S2. Double-layer co-extrusion molding: The core melt and the sheath melt are simultaneously fed into the composite mold and extruded through the annular die of the composite mold to form a core-sheath composite filament with TPU elastic core filament inside and matte PBT shaping layer outside. During extrusion, the radial thickness ratio of TPU elastic core filament to matte PBT shaping layer on the filament is controlled to be 1:2.5. S3, Multi-stage drawing: The co-extruded filaments are subjected to ultra-low-speed multi-stage drawing. The drawing is divided into several drawing segments, which are carried out sequentially. The drawing speed of each drawing segment increases progressively. After segmented progressive drawing, the filaments are stretched to the set final diameter. The molecular chains in the filaments are gradually oriented and a network elastic fiber structure is built inside. This avoids filament breakage or interlayer delamination between the TPU elastic core filament and the matte PBT shaping layer caused by one-time high-speed drawing, and ensures the upper limit of the stretching and the resilience stability of the eyelash filaments. S4. Intermittent Stamping and Grooving: The drawn wire is kept in a pre-stretched state under traction tension and intermittently conveyed by a stepping traction mechanism. Each time the wire comes to rest, a pair of upper and lower separate stamping dies close. Semi-circular grooves are formed on the lower surface of the upper stamping die and the upper surface of the lower stamping die. When the two semi-circular grooves close, they combine to form a circular cavity that matches the outer diameter of the wire. Several semi-annular thin-plate ribs are equidistantly arranged along the groove axis at the bottom of each semi-circular groove. The semi-annular thin-plate ribs of the upper stamping die correspond one-to-one with the semi-annular thin-plate ribs of the lower stamping die. When the dies close, the corresponding upper and lower semi-annular thin-plate ribs combine to form several annular ribs that surround the circular cavity. The temperature of the stamping die is heated to a temperature higher than the glass transition temperature of the matte PBT molding layer and lower than... At the softening temperature of the TPU elastic core filament, several annular ribs are used to stamp the outer wall of the filament around the circumference during mold closing. In one mold closing, several micro-telescopic control grooves are simultaneously stamped on the filament and arranged at equal intervals along the filament axis. The micro-telescopic control grooves surround the filament, and the stamping depth is less than the wall thickness of the matte PBT shaping layer. After stamping, the upper and lower stamping dies open, and the stepping traction mechanism conveys the filament forward for the length of a circular cavity. The above mold closing and stamping action is repeated, so that several micro-telescopic control grooves are continuously formed along the entire length of the filament and arranged at equal intervals along the filament axis. After all the filaments are stamped, the traction tension is released, the TPU elastic core filament elastically retracts and axially presses the matte PBT shaping layer, so that the two side walls of each micro-telescopic control groove are pressed together to form a narrow slit groove. S5. Low temperature setting and slitting: The filaments after pressing are placed in a 45℃ environment for 45 minutes to set and shape. During the setting process, the elastic pores inside the filaments are retained. Then the filaments are slid to obtain eyelash filaments of a set length. The slitting point avoids the opening position of the micro telescopic control groove. S6. Assembly and Shaping: Arrange several eyelash strands according to the set arc, aligning the roots of each eyelash strand. Attach the WPU elastic transparent filament along the root alignment line to the roots of the eyelash strands. Apply transparent adhesive to the joint between the WPU elastic transparent filament and the eyelash strand roots, inserting the roots of each eyelash strand into the transparent adhesive by 0.02~0.05mm. Fill the gaps between the roots of each eyelash strand with the transparent adhesive. After the transparent adhesive has cured to form a transparent adhesive layer, trim it by removing excess adhesive and rough edges from the bottom edge of the transparent adhesive layer, making the edge of the transparent adhesive layer flush with the edge of the WPU elastic transparent filament. This yields stretchable elastic false eyelashes.

[0011] Preferably, the heating temperature of the stamping die in S4 is 80±5℃, the pre-stretching amount of the wire in S4 is less than its elastic tensile limit, and the raised edges of the semi-annular thin sheet ribs in S4 are all rounded.

[0012] Compared with the prior art, the beneficial effects of the present invention are: In this invention, the structure, including an elastic eyelash base strip, TPU elastic core filaments, a matte PBT shaping layer, and micro-telescopic control grooves, allows the TPU elastic core filaments to stretch and deform when the eyelashes are subjected to axial tension, and to spring back to their original position after the tension is removed. This reduces the pulling on the natural eyelashes during wear. The matte PBT shaping layer maintains the firm and curled shape of the eyelashes and limits their maximum stretch, ensuring that the eyelashes balance stretchability and shaping effect, preventing them from becoming limp due to elasticity. The micro-telescopic control grooves open simultaneously when the eyelashes are subjected to axial tension to disperse the amount of stretch. This design avoids excessive stretching and failure of the eyelashes, ensuring that the eyelashes do not break or deform after repeated pulling, resulting in an invisible and natural look and a longer lifespan. The elastic eyelash base strip can stretch and automatically rebound along the overall eye contour, enabling stretchable and elastic false eyelashes to adapt to different eye shapes and dynamic eye deformations. This improves the compatibility and fit of false eyelashes with various eye shapes, making them more comfortable to wear, longer-lasting, and extending the product's lifespan. It solves the problems of existing false eyelashes where the eyelashes and base strips lack the ability to stretch and rebound, leading to pulling on natural eyelashes, easy collapse and deformation, poor fit, and short lifespan. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a partial cross-sectional view of the eyelash fibers of the present invention; Figure 3 This is a schematic diagram of the ingredients used in the preparation of the eyelash strands of the present invention.

[0014] In the image: 1. Elastic eyelash base strip; 11. WPU elastic transparent yarn; 12. Transparent adhesive layer; 2. Eyelash yarn; 21. TPU elastic core yarn; 22. Matte PBT shaping layer; 23. Micro telescopic control groove. Detailed Implementation

[0015] Please see Figure 1-3 The present invention provides a technical solution: A stretchable elastic false eyelashes includes an elastic eyelash base strip 1 and a plurality of eyelash filaments 2 implanted on the elastic eyelash base strip 1. The roots of the plurality of eyelash filaments 2 are arranged sequentially and fixed along the length direction of the elastic eyelash base strip 1. Each eyelash filament 2 consists of a core-sheath composite structure composed of a TPU elastic core filament 21 and a matte PBT shaping layer 22 covering the outside of the TPU elastic core filament 21. The TPU elastic core filament 21 is used to stretch and deform when the eyelash filament 2 is subjected to axial tension and to drive the eyelash filament 2 to rebound and return to its original position after the tension is removed. The matte PBT shaping layer 22 is used to maintain the stiff and curled shape of the eyelash filament 2 and limit its maximum stretching range. The outer wall of the matte PBT shaping layer 22 has openings. Several micro-telescopic control grooves 23 are arranged equidistantly along the axis. Each micro-telescopic control groove 23 is a circumferential narrow slit-shaped groove that surrounds the eyelash filament 2. When the eyelash filament 2 is not stretched, the two side walls of the groove opening of the micro-telescopic control groove 23 are in contact. When the eyelash filament 2 is stretched axially, the groove opening of each micro-telescopic control groove 23 opens synchronously to disperse the stretching amount of the eyelash filament 2. The elastic eyelash base strip 1 includes WPU elastic transparent yarn 11 that is attached to the roots of several eyelash filaments 2 and a transparent adhesive layer 12 that bonds and fixes the WPU elastic transparent yarn 11 to the roots of several eyelash filaments 2. The elastic eyelash base strip 1 has full-area stretching and rebound capability and can stretch and rebound automatically with the overall eye contour.

[0016] The depth of the micro-telescopic control groove 23 is smaller than the wall thickness of the matte PBT shaping layer 22. The edges of the micro-telescopic control groove 23 are all rounded. This design ensures that a portion of the matte PBT shaping layer 22 is always present between the bottom of the micro-telescopic control groove 23 and the outer wall of the TPU elastic core filament 21, preventing damage to the TPU elastic core filament 21 during groove opening. This ensures that the complete TPU elastic core filament 21 provides the rebound force when the eyelash filament 2 is stretched. At the same time, the rounded edges of the groove opening eliminate sharp edges on the outer wall of the eyelash filament 2, reducing the foreign body sensation during wearing and touching, and preventing stress concentration and cracking at the groove edge during repeated opening and closing. The radial thickness ratio of the TPU elastic core filament 21 to the matte PBT shaping layer 22 is 1:2.5. The roots of several eyelash filaments 2 are inserted into the transparent adhesive layer 12 to a depth of 0.02~0.0.05mm, this setting ensures a reasonable thickness ratio between the TPU elastic core filament 21 and the matte PBT setting layer 22. The thickness of the matte PBT setting layer 22 is sufficient to maintain the stiff and curled shape of the eyelash filament 2, while the elasticity of the TPU elastic core filament 21 is sufficient to drive the overall rebound of the eyelash filament 2, balancing the setting effect and tensile rebound performance of the eyelash filament 2. At the same time, the depth at which the root of the eyelash filament 2 is inserted into the transparent adhesive layer 12 ensures the bonding area between the eyelash filament 2 and the transparent adhesive layer 12. When the eyelash filament 2 is stretched, the tension is evenly distributed to the root of each eyelash filament 2 through the transparent adhesive layer 12, preventing the root of the eyelash filament 2 from coming out of the transparent adhesive layer 12, thus eliminating hair loss and glue separation problems during wearing and makeup removal. The raw material of the TPU elastic core filament 21 includes thermoplastic polyurethane (TPU) by weight. The TPU elastic core filament 21 contains 90 parts of elastic toughening agent, 8 parts of elastic toughening agent, and 2 parts of anti-yellowing agent. The elastic toughening agent is used to improve the repeated stretching resistance of the TPU elastic core filament 21, preventing the eyelash filament 2 from loosening or breaking after repeated stretching. The anti-yellowing agent is used to inhibit the yellowing and aging of the TPU elastic core filament 21 under long-term use and in contact with makeup remover and sweat, ensuring the long-term stability of the elastic performance of the eyelash filament 2. This setting makes the material ratio of the TPU elastic core filament 21 reasonable, ensuring the stretching and rebound performance of the eyelash filament 2 while improving the repeated stretching resistance and anti-yellowing and anti-aging ability of the eyelash filament 2, so that the eyelash filament 2 maintains its elastic stability after repeated stretching and has a long service life. The matte PBT shaping layer 22 contains, by weight, 68 parts of flexible PBT, 12 parts of silicone micro powder, and TPE elastomer. The product contains 18 parts of silicone micropowder to create a matte texture on the outer wall of the matte PBT setting layer 22, making the appearance of the eyelash strands 2 resemble real eyelashes. TPE elastomer is used to improve the flexibility of the matte PBT setting layer 22, allowing it to stretch and rebound synchronously with the TPU elastic core filament 21 without cracking. The smoothing agent improves the surface smoothness of the outer wall of the matte PBT setting layer 22, reducing the foreign object sensation at the opening of the micro-stretch control groove 23. This configuration ensures a reasonable material ratio for the matte PBT setting layer 22, guaranteeing the stiff, curled setting effect of the eyelash strands 2 while giving the matte PBT setting layer 22 a realistic matte texture, flexible and crack-resistant properties, and a smooth feel, thus enhancing the natural appearance and wearing comfort of the eyelash strands 2.

[0017] A preparation method includes the following steps: S1. Batching and Plasticizing: Prepare core layer raw materials and sheath layer raw materials according to the mass parts. After mixing the two raw materials separately, send them to two extruders for melt plasticizing to obtain core layer melt and sheath layer melt. S2. Double-layer co-extrusion molding: The core melt and the sheath melt are simultaneously fed into the composite mold and extruded through the annular die of the composite mold to form a core-sheath composite filament with TPU elastic core filament 21 inside and matte PBT shaping layer 22 outside. During extrusion, the ratio of the radial thickness of TPU elastic core filament 21 to matte PBT shaping layer 22 on the filament is controlled to be 1:2.5. S3, Multi-stage drawing: The co-extruded filaments are subjected to ultra-low-speed multi-stage drawing. The drawing is divided into several drawing segments and carried out sequentially. The drawing speed of each drawing segment increases progressively. After the segmented progressive drawing, the filaments are stretched to the set final diameter. The molecular chains in the filaments are gradually oriented and a network elastic fiber structure is built inside. This avoids the filaments from breaking or the interlayer delamination between the TPU elastic core filament 21 and the matte PBT shaping layer 22 caused by one-time high-speed drawing, and ensures the upper limit of the stretch and the elasticity stability of the eyelash filaments 2. S4. Intermittent Stamping and Grooving: The drawn filament is kept in a pre-stretched state under traction tension and intermittently conveyed by a stepping traction mechanism. Each time the filament comes to rest, a pair of upper and lower separate stamping dies close. Semi-circular grooves are formed on the lower surface of the upper stamping die and the upper surface of the lower stamping die. When the two semi-circular grooves close, they are combined to form a circular cavity that matches the outer diameter of the filament. The bottom of each semi-circular groove is provided with several semi-annular thin sheet ribs equidistantly arranged along the groove axis. The semi-annular thin sheet ribs of the upper stamping die correspond one-to-one with the semi-annular thin sheet ribs of the lower stamping die. When the dies close, the corresponding upper and lower semi-annular thin sheet ribs are combined to form several annular ribs that surround the circular cavity. The temperature of the stamping die is heated to a temperature higher than the glass transition temperature of the matte PBT shaping layer 22 but lower than the TPU elastic core. The softening temperature of the filament 21 is such that when the mold is closed, several annular ribs stamp the outer wall of the filament around the entire circumference. In one mold closing, several micro-telescopic control grooves 23 are simultaneously stamped on the filament and arranged at equal intervals along the filament axis. The micro-telescopic control grooves 23 surround the filament and the stamping depth is less than the wall thickness of the matte PBT shaping layer 22. After the stamping is completed, the upper and lower stamping dies open, and the stepping traction mechanism conveys the filament forward for the length of a circular cavity. The above mold closing and stamping action is repeated, that is, several micro-telescopic control grooves 23 arranged at equal intervals along the filament axis are continuously formed along the entire length of the filament. After all the filaments are stamped, the traction tension is released, the TPU elastic core filament 21 elastically retracts and axially presses the matte PBT shaping layer 22, so that the two side walls of the groove opening of each micro-telescopic control groove 23 are pressed together to form a narrow slit groove. S5. Low temperature setting and slitting: The filament after pressing is placed in a 45℃ environment for 45 minutes to keep it warm and set. During the setting process, the elastic pores inside the filament are retained. Then the filament is slid to obtain eyelash filaments 2 of a set length. The slitting point avoids the opening position of the micro telescopic control groove 23. S6. Assembly and shaping: Arrange several eyelash strands 2 according to the set arc, aligning the roots of each eyelash strand 2. Attach the WPU elastic transparent yarn 11 along the root alignment line to the roots of the eyelash strands 2. Apply transparent adhesive to the joint between the WPU elastic transparent yarn 11 and the roots of the eyelash strands 2, inserting the roots of each eyelash strand 2 into the transparent adhesive by 0.02~0.05mm. Fill the gaps between the roots of each eyelash strand 2 with the transparent adhesive. After the transparent adhesive cures to form a transparent adhesive layer 12, trim it by removing excess adhesive and rough edges from the bottom edge of the transparent adhesive layer 12, making the edge of the transparent adhesive layer 12 flush with the edge of the WPU elastic transparent yarn 11, thus obtaining stretchable elastic false eyelashes.

[0018] The heating temperature of the stamping die in S4 is 80±5℃. The pre-stretch amount of the filament in S4 is less than its elastic tensile limit. The raised edges of the semi-annular thin sheet ribs in S4 are all rounded. This setting ensures that the stamping temperature is higher than the glass transition temperature of the matte PBT shaping layer 22. During stamping, the molecular chain segments of the matte PBT shaping layer 22 have sufficient flexibility. The stamped micro-expansion control groove 23 has a stable shape and does not spring back, and the groove edge does not crack. Moreover, this temperature is lower than the softness of the TPU elastic core filament 21. The elastic properties of the TPU elastic core filament 21 are not affected by the temperature during the stamping process; the pre-stretch amount of the filament is within the elastic deformation range, and after the traction tension is removed, the filament and the slots of each micro-telescopic control groove 23 can fully rebound and be pressed and fitted; at the same time, the rounded corners of the raised edges of the semi-annular thin sheet ribs make the edges of the stamped micro-telescopic control groove 23 smooth and without sharp corners, avoiding stress concentration and cracking of the groove edges during repeated opening and closing, and reducing the foreign object feel of the outer wall of the eyelash filament 2.

[0019] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A stretchable elastic false eyelash, comprising an elastic eyelash base strip (1) and a plurality of eyelash strands (2) implanted on the elastic eyelash base strip (1), characterized in that: The roots of several eyelash strands (2) are arranged and fixed sequentially along the length of the elastic eyelash base strip (1). Each eyelash strand (2) consists of a core-sheath composite structure composed of a TPU elastic core strand (21) and a matte PBT shaping layer (22) covering the outside of the TPU elastic core strand (21). The outer wall of the matte PBT shaping layer (22) is provided with several micro-telescopic control grooves (23) arranged axially at equal intervals. Each micro-telescopic control groove (23) is a circumferential narrow slit that surrounds the eyelash strand (2). The groove, when the eyelash filament (2) is in an unstretched state, the two side walls of the groove opening of the micro-telescopic control groove (23) are in contact. When the eyelash filament (2) is subjected to axial stretching, the groove openings of each micro-telescopic control groove (23) open synchronously to disperse the stretching amount of the eyelash filament (2). The elastic eyelash base strip (1) includes WPU elastic transparent yarn (11) that is attached to the roots of several eyelash filaments (2) and a transparent adhesive layer (12) that bonds and fixes the WPU elastic transparent yarn (11) to the roots of several eyelash filaments (2).

2. The stretchable elastic false eyelashes according to claim 1, characterized in that: The groove depth of the micro telescopic control groove (23) is smaller than the wall thickness of the matte PBT shaping layer (22), and the groove edges of the micro telescopic control groove (23) are all rounded.

3. The stretchable elastic false eyelashes according to claim 1, characterized in that: The radial thickness ratio of the TPU elastic core filament (21) to the matte PBT shaping layer (22) is 1:2.5, and the roots of several eyelash filaments (2) are inserted into the transparent adhesive layer (12) with an insertion depth of 0.02~0.05mm.

4. The stretchable elastic false eyelashes according to claim 1, characterized in that: The raw materials of the TPU elastic core filament (21) include, by weight, 90 parts of thermoplastic polyurethane (TPU), 8 parts of elastic toughening agent, and 2 parts of anti-yellowing agent.

5. The stretchable elastic false eyelashes according to claim 1, characterized in that: The raw materials of the matte PBT shaping layer (22) include 68 parts of flexible PBT, 12 parts of silicone micro powder, 18 parts of TPE elastomer, and 2 parts of smoothing agent by mass.

6. A method for preparing a stretchable elastic false eyelash as described in claims 1-5, characterized in that, Includes the following steps: S1. Batching and Plasticizing: Prepare core layer raw materials and sheath layer raw materials according to the mass parts. After mixing the two raw materials separately, send them to two extruders for melt plasticizing to obtain core layer melt and sheath layer melt. S2, Double-layer co-extrusion molding: The core melt and the sheath melt are simultaneously fed into the composite mold and extruded through the annular die of the composite mold to form a core-sheath composite filament with TPU elastic core filament (21) inside and matte PBT shaping layer (22) outside. During extrusion, the ratio of the radial thickness of TPU elastic core filament (21) to matte PBT shaping layer (22) on the filament is controlled to be 1:2.

5. S3, Multi-stage drawing: The co-extruded filaments are subjected to ultra-low speed multi-stage drawing. The drawing is divided into several drawing segments and carried out sequentially. The drawing speed of each drawing segment increases gradually. After the segmented progressive drawing, the filaments are stretched to the set final diameter. The molecular chains in the filaments gradually orient and build a network elastic fiber structure inside. S4. Intermittent stamping and grooving: The drawn filament is kept in a pre-stretched state under traction tension and intermittently conveyed by a stepping traction mechanism. Each time the filament is stationary, a pair of upper and lower separate stamping dies are closed. The lower surface of the upper stamping die and the upper surface of the lower stamping die are both provided with semi-circular grooves. When the two semi-circular grooves are closed, they are combined to form a circular cavity that matches the outer diameter of the filament. The bottom of the two semi-circular grooves is provided with several semi-annular thin sheet ribs that are equidistantly arranged along the groove axis. The semi-annular thin sheet ribs of the upper stamping die correspond one-to-one with the semi-annular thin sheet ribs of the lower stamping die. When the dies are closed, the corresponding upper and lower semi-annular thin sheet ribs are combined to form several annular ribs that surround the circular cavity. The temperature of the stamping die is heated to a temperature higher than the glass transition temperature of the matte PBT shaping layer (22) and lower than the softness temperature of the TPU elastic core filament (21). When the temperature is reached and the mold is closed, several annular ribs are stamped around the outer wall of the filament. In one mold closing, several micro-telescopic control grooves (23) are simultaneously stamped on the filament and arranged at equal intervals along the filament axis. The micro-telescopic control grooves (23) surround the filament and the stamping depth is less than the wall thickness of the matte PBT shaping layer (22). After the stamping is completed, the upper and lower stamping dies are opened and the stepping traction mechanism conveys the filament forward for the length of a circular cavity. The above mold closing and stamping action is repeated, so that several micro-telescopic control grooves (23) are continuously formed along the entire length of the filament and arranged at equal intervals along the filament axis. After all the filaments are stamped, the traction tension is released, the TPU elastic core filament (21) elastically retracts and axially presses the matte PBT shaping layer (22), so that the two side walls of the groove opening of each micro-telescopic control groove (23) are pressed together to form a narrow slit groove. S5. Low temperature setting and cutting: The filament after pressing is placed in a 45℃ environment for 45 minutes to keep it warm and set. During the setting process, the elastic pores inside the filament are retained. Then the filament is cut to obtain eyelash filaments (2) of a set length. The cutting point avoids the opening position of the micro telescopic control groove (23). S6. Assembly and shaping: Arrange several eyelash strands (2) according to the set arc, align the roots of each eyelash strand (2), attach the WPU elastic transparent yarn (11) along the root alignment line to the roots of several eyelash strands (2), apply transparent glue to the joint between the WPU elastic transparent yarn (11) and the roots of the eyelash strands (2), insert the roots of each eyelash strand (2) into the transparent glue by 0.02~0.05mm, fill the gap between the roots of each eyelash strand (2), after the transparent glue has cured to form a transparent glue layer (12), trim it, cut off the excess glue and rough edges at the bottom edge of the transparent glue layer (12), so that the edge of the transparent glue layer (12) is flush with the edge of the WPU elastic transparent yarn (11), and a stretchable elastic false eyelash is obtained.

7. The preparation method according to claim 6, characterized in that: The heating temperature of the stamping die in S4 is 80±5℃, the pre-stretch amount of the wire in S4 is less than its elastic tensile limit, and the raised edges of the semi-annular thin sheet ribs in S4 are all rounded.

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