PLA-pHA side-by-side composite elastic fiber and preparation method thereof

Abstract

The application discloses a kind of PLA-PHA parallel composite elastic fiber and preparation method thereof, belong to composite elastic fiber field;Preparation method includes: first, PLA and polysilicic siloxane are melt extruded granulation in double screw extruder and obtain master batch, then master batch is melt mixed with PLA and obtains component A;After PHA is modified by double end epoxy siloxane chain extension, it is melt mixed with PLA and obtains component B;Component A and component B are prepared by composite spinning and obtain parallel composite elastic fiber;After PHA is chain-extended by double end epoxy siloxane, the relative molecular mass thereof can be increased, and the melt strength is improved;At the same time, siloxane segment can play the role of internal lubrication to improve the fluidity of melt, can reduce its processing temperature, further reduce the thermal degradation of PHA, ensure necessary spinnability.In addition, the introduction of polysilicic siloxane in component A improves the melt flowability of PLA, reduces the viscosity difference with component B, ensures that the composite fiber forms good interface structure, lays the foundation for the macrostructure of fiber curling;At the same time, polysilicic siloxane in component A can promote the nucleation and crystallization of PLA, and the PLA in component B is blended with the chain-extended PHA component to construct gradient distribution structure by heterogeneous flow control, which increases the difference of radial microstructure in the composite fiber, and is conducive to promoting the formation of fiber curling.

Description

Technical Field

[0001] This invention belongs to the field of composite elastic fibers, specifically relating to a PLA-PHA parallel composite elastic fiber and its preparation method. Background Technology

[0002] Bicomponent parallel composite elastic fiber is a fiber composed of two polymers with good compatibility and significantly different heat shrinkage properties. When heated, the fiber forms a permanent helical three-dimensional crimp structure due to the different heat shrinkage rates of the two components, thus endowing the fiber with excellent crimp elasticity and elastic recovery properties. It also meets the needs of most fabrics in terms of comfort, dyeability, and weavability. It not only solves many problems of traditional spandex, such as difficulty in dyeing, excessive elasticity, complex weaving, and easy aging during use, but also allows it to be woven directly without the need for core-spun yarn treatment.

[0003] Currently, the development of parallel composite elastic fibers mainly involves combinations of different petroleum-based materials, such as polyethylene terephthalate (PET) / polypropylene terephthalate (PTT), high and low viscosity polyesters, polypropylene / polyamide 6, and polypropylene / ethylene octene copolymers. However, petroleum-based polymers face certain challenges in terms of resource utilization and environmental protection.

[0004] In recent years, green and low-carbon functionality has become the mainstream trend in the development of fiber materials. Polylactic acid (PLA) and polyhydroxyalkanoates (PHA) have unparalleled advantages in designing parallel composite elastic fibers due to their bio-based origin and biodegradability. The glass transition temperature of PLA is typically around 55-60℃, while that of PHA is typically around -20℃ to 10℃. This significant difference in glass transition temperatures between the two polymers results in a marked difference in thermal shrinkage properties after heat treatment of the composite fibers, theoretically contributing to the formation of a good crimp structure. However, PHA polymers have a narrow thermal processing window and are easily degraded during processing, leading to decreased melt strength and severe fiber breakage and fuzzing. Furthermore, PLA and PHA are not completely thermodynamically miscible, which to some extent reduces the interfacial bonding force between the two components of the composite fiber, affecting the asymmetric stress transfer between the components and reducing the fiber crimp performance.

[0005] Therefore, further enhancing the formation of crimp on the basis of improving the forming performance of PLA-PHA composite fibers is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a PLA-PHA parallel composite elastic fiber and its preparation method, thereby solving the problems in the prior art.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing PLA-PHA side-by-side composite elastic fibers includes the following steps:

[0009] First, PLA and polysilsesquioxane are melt-extruded and granulated in a twin-screw extruder at a mass ratio of (7-8):(2-3) to obtain masterbatch. Then, the masterbatch is melt-mixed with PLA to obtain component A.

[0010] Component B is obtained by melt mixing PHA with PLA after undergoing chain extension modification with di-terminated epoxy siloxanes.

[0011] Parallel composite elastic fibers were prepared by composite spinning of components A and B.

[0012] Furthermore, in component A, the mass ratio of PLA to polysilsesquioxane is (97-99.5):(0.5-3).

[0013] Furthermore, in component B, the mass ratio of chain-extended modified PHA to PLA is (25-75):(25-75).

[0014] Furthermore, in the chain-extended modified PHA, the mass ratio of PHA to di-terminated epoxy siloxane is (97.5-99.5):(0.5-2.5).

[0015] Furthermore, in the composite spinning process, the mass ratio of component A to component B is (20-80):(20-80).

[0016] Furthermore, the number-average molecular weight of the PLA is 200,000 to 300,000 g / mol, and the number-average molecular weight of the PHA is 150,000 to 300,000 g / mol.

[0017] Further, the polysilsesquioxane is one or more of the following: heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane, heptaoctyltrisilyl alcohol cage-like polysilsesquioxane, heptadodecyltrisilyl alcohol cage-like polysilsesquioxane, octamethyl cage-like polysilsesquioxane, and octa(isobutyltrisilsesquioxane).

[0018] Further, the PHA is one of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-3-hydroxyvalerate), poly(3-hydroxybutyrate-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-4-hydroxybutyrate).

[0019] Further, the dual-terminated epoxy siloxane is one or more of the following: di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane, 1,1,3,3-tetramethyl-1,3-di[3-(epoxyethylmethoxy)propyl]disiloxane, 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]tetramethyldisiloxane, and 1,5-bis(epoxypropoxypropyl)-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane.

[0020] A PLA-PHA parallel composite elastic fiber is prepared using the above-described method for preparing PLA-PHA parallel composite elastic fibers.

[0021] The beneficial effects of this invention are:

[0022] 1. The present invention uses a double-terminated epoxy siloxane to extend the chain of PHA. On the one hand, it "dynamically repairs" the molecular chains that are degraded during the granulation process of PHA, thereby improving its melt strength. At the same time, during the spinning and melting process, the siloxane segments can act as internal lubricants to improve the fluidity of the melt, thereby reducing its processing temperature, further reducing the thermal degradation of PHA, and ensuring the necessary spinnability.

[0023] 2. This invention employs a blend of PLA and chain-extended modified PHA components to construct a gradient distribution structure through heterogeneous flow control. Meanwhile, polysilsesquioxane is introduced into the polylactic acid component to improve its melt flowability and promote nucleation and crystallization during fiber forming. This structure not only facilitates the formation of a good macroscopic interface structure in the composite fiber but also increases the difference in microstructure between components, increases the magnitude of radial asymmetric stress in the composite fiber, and promotes fiber crimping.

[0024] 3. The PLA / PHA parallel composite fiber of the present invention has the characteristics of being bio-based and biodegradable, and has good elasticity and mechanical properties. The preparation method is simple, which meets the development needs of green and low carbon fiber, and has broad application prospects in clothing, home textiles and other fields. Detailed Implementation

[0025] The technical solutions will now be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The following examples illustrate the preparation process of PLA-PHA parallel composite elastic fibers;

[0027] In the following embodiments, the raw materials are selected as follows:

[0028] Poly(3-hydroxybutyrate) (PHB) was purchased from Zhuhai Medbio Biotechnology Co., Ltd.

[0029] Poly(3-hydroxybutyrate-4-hydroxybutyrate) (P34HB) was purchased from Zhuhai Medbio Biotechnology Co., Ltd.

[0030] Poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV) was purchased from Shanghai Shengquan Plastics Co., Ltd.

[0031] Poly(3-hydroxybutyrate-3-hydroxyhexanoate) (PHBHHx)HH has a molar fraction of 11%, manufactured by Kaneka Corporation, Japan.

[0032] Polylactic acid (PLA) was purchased from TotalCopion;

[0033] The heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane was purchased from Guangzhou Xinyi Technology Co., Ltd.

[0034] The heptadecyltrisilyl alcohol cage-like polysilsesquioxane was purchased from Guangzhou Xinyi Technology Co., Ltd.

[0035] Octamethyl cage-like polysilsesquioxane was purchased from Guangzhou Xinyi Technology Co., Ltd.

[0036] Octa-(isobutylsilsesquioxane) CAS No.: 221326-46-1;

[0037] The heptaoctyltrisilyl alcohol cage-like polysilsesquioxane was purchased from Guangzhou Xinyi Technology Co., Ltd.

[0038] Bis[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane was prepared according to the synthesis method reported in the literature (Shen Han. Synthesis of Bis[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane and its UV curing properties [D]. Nanchang University, 2023.).

[0039] 1,1,3,3-Tetramethyl-1,3-bis[3-(epoxyethylmethoxy)propyl]disiloxane CAS No.: 126-80-7;

[0040] 1,3-Bis[2-(3,4-epoxycyclohexyl)ethyl]tetramethyldisiloxane CAS No.: 18724-32-8;

[0041] 1,5-Bis(epoxypropoxypropyl)-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane CAS No.: 865811-59-2.

[0042] Example 1

[0043] The preparation method of PLA-PHA parallel composite elastic fiber includes the following steps:

[0044] S1, component A melt is obtained by melt blending PLA with PLA-polysilsesquioxane masterbatch;

[0045] Specifically:

[0046] 1) PLA-heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane masterbatch was obtained by melt extrusion granulation using a twin-screw extruder. The temperatures of zones I, II, III, IV, V, VI, and VII of the twin-screw extruder were 155℃, 168℃, 168℃, 165℃, 165℃, 162℃, and 162℃, respectively. The content of heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane in the masterbatch was 20wt%.

[0047] 2) Using the masterbatch addition method, PLA chips and PLA-heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane masterbatch are melt-blended at 195℃ through a composite spinning machine screw to obtain component A melt. The amount of masterbatch added is controlled so that the mass ratio of PLA to heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane in component A is 99.5:0.5.

[0048] S2, PHA is chain extended with a double-ended epoxy siloxane and then melt-blended with PLA to obtain component B melt;

[0049] Specifically:

[0050] 1) Poly(3-hydroxybutyrate) and di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane were subjected to a chain extension reaction at a mass ratio of 99.5:0.5 to obtain the chain extension product. The chain extension reaction was carried out in a twin-screw extruder at a chain extension extrusion temperature of 165℃, a negative pressure of -0.05MPa, and a time of 3min.

[0051] 2) Then, the chain-extended product and PLA are melt-blended at 185°C using a composite spinning machine screw at a mass ratio of 25:75 to obtain component B melt; under the extrusion temperature conditions, the zero-shear viscosity of polylactic acid is 200 Pa·S higher than that of poly(3-hydroxybutyrate) after chain extension by di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane.

[0052] The number-average molecular weight of PLA is 200,000 g / mol, and the number-average molecular weight of poly(3-hydroxybutyrate) is 150,000 g / mol.

[0053] S3, parallel composite elastic fibers are prepared by composite spinning of components A and B;

[0054] The main processes of composite spinning include: using a composite spinning machine to extrude component A and component B through a spinneret, followed by cooling, hot stretching, and overfeed winding;

[0055] Components A and B are melted separately in a twin-screw extruder, with melt temperatures of 195°C for component A and 185°C for component B. They are then metered by metering pumps and extruded through spinnerets at a spinning temperature of 188°C. The metering pump speeds are adjusted to achieve a mass ratio of 20:80 for components A and B. During the spinneret extrusion process, the melt shear rate at the spinneret is 3500 s⁻¹. -1 The cooling process uses side-blowing air, with component B facing the airflow direction and component A facing away from it. The airflow temperature is 12°C. The hot stretching is performed at a temperature of 105°C with a stretching ratio of 1.5 times. The overfeed rate for the overfeed winding is 5%.

[0056] Example 2

[0057] The preparation method of PLA-PHA parallel composite elastic fiber includes the following steps:

[0058] S1, component A melt is obtained by melt blending PLA with PLA-polysilsesquioxane masterbatch;

[0059] Specifically:

[0060] 1) PLA-heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane masterbatch was obtained by melt extrusion granulation using a twin-screw extruder. The temperatures of zones I, II, III, IV, V, VI, and VII of the twin-screw extruder were 155℃, 168℃, 168℃, 165℃, 165℃, 162℃, and 162℃, respectively. The content of heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane in the masterbatch was 30wt%.

[0061] 2) Using the masterbatch addition method, PLA chips and PLA-heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane masterbatch are melt-blended at 185°C through a composite spinning machine screw to obtain component A melt. The amount of masterbatch added is controlled so that the mass ratio of PLA to heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane in component A is 97:3.

[0062] S2, PHA is chain extended with a double-ended epoxy siloxane and then melt-blended with PLA to obtain component B melt;

[0063] Specifically:

[0064] 1) Poly(3-hydroxybutyrate) and di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane were subjected to a chain extension reaction at a mass ratio of 97.5:2.5 to obtain a chain extension product. The chain extension reaction was carried out in a twin-screw extruder at a chain extension extrusion temperature of 175℃, a negative pressure of -0.1MPa, and a time of 6min.

[0065] 2) Then, the chain-extended product and PLA were blended at 165°C using a composite spinning machine screw at a mass ratio of 75:25 to obtain component B melt; under the extrusion temperature conditions, the zero-shear viscosity of polylactic acid was 350 Pa·S higher than that of poly(3-hydroxybutyrate) after chain extension by di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane.

[0066] The number-average molecular weight of PLA is 300,000 g / mol, and the number-average molecular weight of poly(3-hydroxybutyrate) is 300,000 g / mol.

[0067] S3, parallel composite elastic fibers are prepared by composite spinning of components A and B;

[0068] The main processes of composite spinning include: using a composite spinning machine to extrude component A and component B through a spinneret, followed by cooling, hot stretching, and overfeed winding;

[0069] Components A and B are melted separately in a twin-screw extruder, with melt temperatures of 185°C for component A and 165°C for component B. They are then metered by metering pumps and extruded through spinnerets at a spinning temperature of 175°C. The metering pump speeds are adjusted to achieve a mass ratio of 80:20 for components A and B. During the spinneret extrusion process, the shear rate at the spinneret is 5000 s⁻¹. -1 The cooling process uses side-blowing air, with component B facing the airflow direction and component A facing away from it. The airflow temperature is 22°C. The hot stretching is performed at a temperature of 150°C with a stretching ratio of 6. The overfeed rate for the overfeed winding is 30%.

[0070] Example 3

[0071] The only difference between this embodiment and Embodiment 1 is that:

[0072] In S1, the polysilsesquioxane is heptaoctyltrisilyl alcohol cage-like polysilsesquioxane;

[0073] In S2, PHA is poly(3-hydroxybutyrate-3-hydroxyvalerate), and the bi-terminated epoxy siloxane is 1,1,3,3-tetramethyl-1,3-bis[3-(epoxyethylmethoxy)propyl]disiloxane.

[0074] Example 4

[0075] The only difference between this embodiment and Embodiment 1 is that:

[0076] In S1, the polysilsesquioxane is a cage-like polysilsesquioxane composed of heptadecyltrisilyl alcohol;

[0077] In S2, PHA is poly(3-hydroxybutyrate-3-hydroxyhexanoate), and the bi-terminated epoxy siloxane is 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]tetramethyldisiloxane.

[0078] Example 5

[0079] The only difference between this embodiment and Embodiment 2 is that:

[0080] In S1, the polysilsesquioxane is octamethyl cage-like polysilsesquioxane;

[0081] In S2, PHA is poly(3-hydroxybutyrate-4-hydroxybutyrate), and the bi-terminated epoxy siloxane is 1,5-bis(epoxypropoxypropyl)-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane.

[0082] Example 6

[0083] The only difference between this embodiment and Embodiment 2 is that:

[0084] In S1, the polysilsesquioxane is octa(isobutylsilsesquioxane);

[0085] In S2, PHA is poly(3-hydroxybutyrate-4-hydroxybutyrate), and the bi-terminated epoxy siloxane is 1,5-bis(epoxypropoxypropyl)-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane.

[0086] Comparative Example 1

[0087] The preparation method of PLA-PHA parallel composite elastic fiber is basically the same as that in Example 1, except that: component A is composed of PLA and component B is composed of PLA and poly(3-hydroxybutyrate).

[0088] Test and verification:

[0089] The composite elastic fibers obtained in Examples 1-6 and Comparative Example 1 were tested and verified.

[0090] The following are the performance testing standards:

[0091] Curl rate and curl recovery rate were tested according to GB / T 14338-2022;

[0092] Tensile breaking strength, tested according to GB / T 14344-1993 standard.

[0093] The experimental results are shown in Table 1 below:

[0094] Table 1. Test data of composite elastic fiber properties obtained from Examples 1-6 and comparative examples.

[0095]

[0096] From the table above, we can see that:

[0097] In Comparative Example 1, no heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane was added to component A, resulting in a high melt viscosity and poor flowability of component A. This increased the viscosity difference with component B, leading to deformation of the interfacial structure of the composite fiber and affecting crimp formation. Meanwhile, in component B, poly(3-hydroxybutyrate) was directly melt-blended with PLA, resulting in severe thermal degradation of poly(3-hydroxybutyrate) and inducing thermal degradation of PLA, which in turn reduced the spinnability of the fiber.

[0098] In Example 1, the addition of heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane to component A improves the flowability of component A and reduces the viscosity difference with component B, which is beneficial for the formation of a good interfacial structure in the composite fiber and lays the macroscopic structural foundation for the formation of crimp. Simultaneously, the chain extension of poly(3-hydroxybutyrate) in component B by di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane not only increases the molecular weight of poly(3-hydroxybutyrate) and ensures spinning stability, but also, due to the "internal lubrication" effect of the introduced siloxane segments, promotes the diffusion of poly(3-hydroxybutyrate) from within component B to the outer side of the fiber, forming a gradient phase structure. Furthermore, the heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane in component A can act as a nucleating agent to promote PLA crystallization, further intensifying the difference in radial structure within the composite fiber, which is beneficial for fiber crimp formation.

[0099] Compared with Example 1, Example 2 strengthens the radial structural differences of the composite fiber by increasing the content of heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane in component A and increasing the mass ratio of PHA after chain extension of double-terminated epoxy siloxane in component B, thereby forming a larger asymmetric stress inside and significantly improving the fiber crimp rate.

[0100] As can be seen from implementations 3 to 6, by appropriately changing the raw materials through this technical route, parallel composite elastic fibers with good crimping properties can be obtained.

[0101] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0102] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for producing a PLA-PHA side-by-side composite elastic fiber, characterized by, Includes the following steps: First, PLA and polysilsesquioxane are melt-extruded and granulated in a twin-screw extruder at a mass ratio of (7-8):(2-3) to obtain masterbatch. Then, the masterbatch is melt-mixed with PLA to obtain component A. Component B is obtained by melt mixing PHA with PLA after undergoing chain extension modification with di-terminated epoxy siloxanes. Parallel composite elastic fibers were prepared by composite spinning of components A and B. The polysilsesquioxane is one or more of the following: heptaisobutyltrisilyl alcohol cage polysilsesquioxane, heptaoctyltrisilyl alcohol cage polysilsesquioxane, heptadodecyltrisilyl alcohol cage polysilsesquioxane, octamethyl cage polysilsesquioxane, and octa(isobutyltrisiloxane). The PHA is one of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-3-hydroxyvalerate), poly(3-hydroxybutyrate-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-4-hydroxybutyrate); The dual-terminated epoxy siloxane is one or more of the following: di[2-(3,4-epoxycyclohexyl)ethyl]hexamethyltrisiloxane, 1,1,3,3-tetramethyl-1,3-di[3-(epoxyethylmethoxy)propyl]disiloxane, 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]tetramethyldisiloxane, and 1,5-bis(epoxypropoxypropyl)-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane.

2. The preparation method of the PLA-PHA parallel composite elastic fiber according to claim 1, characterized in that, In component A, the mass ratio of PLA to polysilsesquioxane is (97-99.5):(0.5-3).

3. The preparation method of the PLA-PHA parallel composite elastic fiber according to claim 1, characterized in that, In component B, the mass ratio of chain-extended modified PHA to PLA is (25-75):(25-75).

4. The preparation method of the PLA-PHA parallel composite elastic fiber according to claim 3, characterized in that, In the chain-extended modified PHA, the mass ratio of PHA to di-terminated epoxy siloxane is (97.5-99.5):(0.5-2.5).

5. The preparation method of the PLA-PHA parallel composite elastic fiber according to claim 1, characterized in that, In the composite spinning process, the mass ratio of component A to component B is (20-80):(20-80).

6. The preparation method of the PLA-PHA parallel composite elastic fiber according to claim 1, characterized in that, The PLA has a number-average molecular weight of 200,000 to 300,000 g / mol, and the PHA has a number-average molecular weight of 150,000 to 300,000 g / mol.

7. A PLA-PHA side-by-side composite elastic fiber, characterized by, Prepared using the method for preparing PLA-PHA parallel composite elastic fibers according to any one of claims 1-6.

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