Modified polylactic acid fiber as well as preparation method and application thereof

Abstract

The invention discloses a modified polylactic acid fiber as well as a preparation method and application thereof. The modified polylactic acid fiber is prepared from the following raw materials in parts by weight: 70-98 parts of polylactic acid, 1-15 parts of modified tackifying resin and 1-15 parts of tackifying resin, wherein the modified tackifying resin is prepared by performing graft modification on tackifying resin and methacrylic acid to form grafted tackifying resin, and then reacting the grafted tackifying resin with poly (methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer. The modified polylactic acid fiber provided by the invention has the characteristic of physical aging resistance, and breaks through the situation that the conventional polylactic acid fiber is easily subjected to physical aging and the strength is reduced, so that the use requirements can be fully met, and the application field is greatly expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber preparation, and specifically relates to a modified polylactic acid fiber and a preparation method and application thereof. Background Art

[0002] The synthetic fibers currently used on a large scale are basically derived from petrochemical resources, such as polyolefins and polyesters. However, petroleum-based resins themselves have limited resources; and the non-degradability of petroleum-based resins can easily cause serious "white" pollution to the environment, sharply increasing CO 2 The emission of gases brings about the environmental problem of global warming. Therefore, it is particularly necessary to develop biodegradable polymer fibers that can be used in the fiber field.

[0003] Among them, the more typical biodegradable plastic is polylactic acid. Polylactic acid (PLA) has good biocompatibility and biodegradability. It can eventually produce carbon dioxide and water after being decomposed by microorganisms during the composting process. It is one of the earliest biodegradable plastics certified by the US Food and Drug Administration (FDA). With the maturity of large-scale production technology of polylactic acid and the reduction of its production cost, polylactic acid fibers with various excellent properties have been prepared in recent years, and their application in medical, textile and other fields has attracted widespread attention. Polylactic acid fiber is made of corn, wheat, starch, etc. as raw materials, fermented to produce lactic acid, and then prepared by polymerization and melt spinning. However, polylactic acid fiber has the problem of low strength, especially below the glass transition temperature, it is very easy to undergo physical aging, which leads to a further decrease in the strength of polylactic acid (Fiber and polymers, 2021, 22 (9): 26022611; ACS Appl.Polm.materials, 2021, 3, 1406-1414).

[0004] There are many public reports on the preparation of PLA fibers. A method for preparing high-strength retention rate polylactic acid monofilaments is disclosed in the patent with publication number CN1 17626481A. A tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer layer is used to completely cover the outside of the polylactic acid monofilament body, isolating the polylactic acid body from direct contact with the air, slowing down the decomposition rate of polylactic acid, and thus improving the strength retention rate of the polylactic acid fiber. Since this method increases the process difficulty of preparing polylactic acid fibers and requires special equipment, it is impossible to promote it on a large scale. A method for preparing aging-resistant fibers is disclosed in the patent with publication number CN116463785A. By using a specific cross-linked silicone rubber as a reinforcing material for the fiber and by the synergistic effect of polyvinyl alcohol, a polylactic acid fiber with a fiber strength of 3.5-7.0 cN / dtex and a strength retention rate of 91.4-95.7% can be prepared. Due to the water absorption characteristics of polyvinyl alcohol, when stored in certain environments, such as high humidity environments, water molecules will enter the polylactic acid matrix and promote the hydrolysis reaction of polylactic acid, which may cause the strength of polylactic acid fibers to decrease.

[0005] Although the above-mentioned known technologies can prepare PLA fibers, they still have the following limitations: (1) Special equipment and processes are required to prepare PLA fibers with high strength retention, which cannot be promoted on a large scale; (2) Due to their water absorption characteristics, the strength retention of some high-strength-retention PLA fiber-reinforced materials cannot be guaranteed under high temperature and high humidity conditions; (3) The existing strength retention rate only tests the changes in a short period of time, and the strength retention rate over a long period of time cannot be guaranteed. Summary of the invention

[0006] The main purpose of the present invention is to provide a modified polylactic acid fiber and a preparation method and application thereof, so as to overcome the problems of severe strength attenuation and poor strength retention in the prior art.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0008] The embodiment of the present invention provides a modified polylactic acid fiber, and the raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 70-98 parts of polylactic acid, 1-15 parts of modified tackifying resin and 1-15 parts of tackifying resin;

[0009] The modified tackifying resin is prepared by grafting tackifying resin with methacrylic acid to form a grafted tackifying resin, and then reacting with poly (methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer.

[0010] The present invention also provides a method for preparing the modified polylactic acid fiber, which comprises:

[0011] The modified polylactic acid fiber is prepared by blending polylactic acid, modified tackifying resin and tackifying resin, granulating, melt spinning and heat drawing.

[0012] The embodiment of the present invention also provides the use of the aforementioned modified polylactic acid fiber in the preparation of textile materials.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The present invention improves the drawability of polylactic acid fiber by combining polylactic acid, modified tackifying resin and tackifying resin with specific component contents, and can obtain modified polylactic acid fiber with high strength retention after 180 days of physical aging while ensuring strength;

[0015] (2) The formula system designed by the present invention is relatively simple, but can still achieve high strength retention of polylactic acid fiber;

[0016] (3) The low molecular weight tackifying resin of the present invention will migrate to the surface of the polylactic acid during processing to form a sticky layer, which can make the fibers adhere to each other, improve the energy release capacity during the tensile test, and indirectly improve the strength retention rate of the polylactic acid fiber;

[0017] (4) The addition of the modified tackifying resin in the present invention significantly enhances the compatibility of polylactic acid and the tackifying resin (the surface of the tackifying resin is coated with the modified tackifying resin, which greatly reduces the size of the dispersed phase and makes the network structure more compact), forming a very strong bonding force; even under the process of hot stretching and tensile testing, there is still no desorption, breakage and the like;

[0018] (5) The modified tackifying resin and the tackifying resin in the polylactic acid fiber of the present invention cooperate to form a viscoelastic three-dimensional network structure, thereby improving the stability of the microstructure in the fiber and significantly improving the strength retention rate of the polylactic acid fiber;

[0019] (6) The present invention uses polylactic acid with a relatively high molecular weight, which can improve the melt strength of the blending system and improve the mechanical properties of the polylactic acid fiber; the polylactic acid selected has a relatively high molar content of the L optical isomer, which can improve the crystallization ability of the blending system, thereby improving the crystallinity and mechanical properties of the modified polylactic acid fiber; the modified thickening resin with a medium weight-average molecular weight is selected, which significantly improves the compatibility between the thickening resin and the polylactic acid, can improve the adhesion and stretchability of the blending system, and give the modified polylactic acid fiber a high mutual adhesion; the modified polylactic acid fiber maintains high strength after physical aging and has the characteristic of physical aging resistance, which breaks through the problem that conventional polylactic acid fibers are easily physically aged and their strength is reduced, thereby fully meeting the use requirements and greatly expanding its application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is the hydrogen nuclear magnetic spectrum of the modified tackifying resin prepared in Example 1 of the present invention;

[0022] Figure 2 Graph showing the mechanical properties of the modified polylactic acid fiber prepared in Example 1 of the present invention before and after aging;

[0023] Figure 3 3 is a scanning electron microscope image of the residue after Soxhlet extraction of the modified polylactic acid fiber prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In view of the defects of the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the present invention, unless otherwise specified, "PLA" refers to polylactic acid; "MA" refers to methacrylic acid; "MMA" refers to methyl methacrylate; and "GMA" refers to glycidyl methacrylate.

[0026] Specifically, as one aspect of the technical solution of the present invention, it relates to a modified polylactic acid fiber, and the raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 70-98 parts of polylactic acid, 1-15 parts of modified tackifying resin and 1-15 parts of tackifying resin;

[0027] The modified tackifying resin is prepared by grafting tackifying resin with methacrylic acid to form a grafted tackifying resin, and then reacting with poly (methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer.

[0028] Furthermore, the total weight of raw materials used to prepare the modified polylactic acid fiber is 100 parts.

[0029] In some preferred embodiments, the poly(methyl methacrylate-co-glycidyl methacrylate) is denoted as: P(MMA-co-GMA).

[0030] In some preferred embodiments, the raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 80-90 parts of polylactic acid, 5-10 parts of modified tackifying resin and 5-10 parts of tackifying resin.

[0031] Furthermore, the raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 80-86 parts of polylactic acid, 8-10 parts of modified tackifying resin and 8-10 parts of tackifying resin.

[0032] In some preferred embodiments, the weight average molecular weight of the polylactic acid is 80,000-500,000, and the molar content of the L optical isomer in the polylactic acid is 85-99%.

[0033] Furthermore, the weight average molecular weight of the polylactic acid is 150,000-350,000, and the molar content of the L optical isomer in the polylactic acid is 94-98%.

[0034] In some preferred embodiments, the weight average molecular weight of the modified tackifying resin is 20,000-120,000.

[0035] Furthermore, the weight average molecular weight of the modified tackifying resin is 40,000-80,000.

[0036] In some preferred embodiments, the tackifying resin includes any one or more combinations of C5 tackifying resin, C5 hydrogenated tackifying resin, C9 hydrogenated tackifying resin, C9 cold-polymerized tackifying resin, C9 hot-polymerized tackifying resin, C5 / C9 copolymerized tackifying resin, terpene resin, and rosin ester, and is not limited thereto.

[0037] In some preferred embodiments, the weight average molecular weight of the tackifying resin is 300-10,000.

[0038] Furthermore, the weight average molecular weight of the tackifying resin is 800-5000.

[0039] In some preferred embodiments, the molar grafting ratio of the grafted tackifying resin is 20-70%.

[0040] Furthermore, the molar grafting ratio of the grafted tackifying resin is 30-55%.

[0041] In some preferred embodiments, the modified polylactic acid fiber is treated at 40° C. and 50 RH% for 180 days, and the strength decay is less than 10%.

[0042] In some preferred embodiments, the modified polylactic acid fiber has a tensile strength of 3.2-5.6 cN / dtex and an elongation at break of 18%-30%.

[0043] In some preferred embodiments, the method for preparing the modified tackifying resin comprises:

[0044] A first mixed reaction system comprising at least a tackifying resin and methacrylic acid is subjected to a first reaction at 100-150° C. for 4-12 minutes to obtain a grafted tackifying resin; wherein the grafted tackifying resin refers to a tackifying resin grafted and modified with methacrylic acid, the purpose of which is to allow the tackifying resin to obtain a carboxyl group that can react with P(MMA-co-GMA);

[0045] Under the conditions of a reaction pressure of 0.5-101 KPa and a temperature of 60-80° C., a second mixed reaction system comprising methyl methacrylate, glycidyl methacrylate, and a solvent is subjected to a second reaction for 6-12 hours to obtain poly(methyl methacrylate-co-glycidyl methacrylate);

[0046] And, the grafted tackifying resin is subjected to a third reaction with poly(methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer under the conditions of a reaction pressure of 0.5-101 KPa and a temperature of 155-195° C. for 1-4 hours to obtain a modified tackifying resin.

[0047] Furthermore, the mass ratio of the tackifying resin to methacrylic acid is 80-98:2-20.

[0048] Furthermore, the mass ratio of the methyl methacrylate, glycidyl methacrylate and the solvent is 25-50:25-35:15-50.

[0049] Furthermore, the mass ratio of the grafted tackifying resin, poly(methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer is 15-30:40-70:15-30.

[0050] Furthermore, the weight average molecular weight of the lactic acid oligomer is 1000-10000.

[0051] Furthermore, the molecular weight of the poly(methyl methacrylate-co-glycidyl methacrylate) is 20,000-120,000.

[0052] Further, the solvent includes any one or more combinations of N,N-dimethylformamide, toluene, and water, but is not limited thereto.

[0053] Furthermore, the preparation method of the modified tackifying resin specifically includes: subjecting a first mixed reaction system comprising a tackifying resin, methacrylic acid, and an initiator in a mass ratio of 80-98:2-20:0.1-1.2 to a first reaction at 100-150°C for 4-12 minutes to obtain a grafted tackifying resin; wherein the initiator includes diisopropylbenzene peroxide and / or dibenzoyl peroxide, but is not limited thereto.

[0054] Furthermore, the preparation method of the modified tackifying resin specifically includes: under the conditions of a reaction pressure of 0.5-101 KPa and a temperature of 60-80°C, a second mixed reaction system containing methyl methacrylate, glycidyl methacrylate, solvent, and initiator in a mass ratio of 25-40:25-30:30-50:0.2-0.5 is subjected to a second reaction for 7-10 hours to obtain poly(methyl methacrylate-co-glycidyl methacrylate); wherein the initiator includes any one or more combinations of azobisisobutyronitrile, azobiscyanovaleric acid, and azobisisoheptylonitrile, and is not limited thereto.

[0055] In some preferred embodiments, the method for preparing the modified tackifying resin comprises the following steps:

[0056] Step (1): reacting 82-96 parts by weight of a tackifying resin (Cx) with 4-18 parts by weight of methacrylic acid (MA) to form a grafted tackifying resin (Cx-g-MA), the reaction temperature being 110-140° C. and the reaction time being 5-10 minutes;

[0057] Step (2): 25-40 parts by weight of methyl methacrylate (MMA), 25-30 parts by weight of glycidyl methacrylate (GMA), and 30-50 parts by weight of N,N-dimethylformamide (DMF) are mixed and reacted to obtain polymethyl methacrylate-glycidyl methacrylate (P(MMA-co-GMA)), the reaction temperature is 65-75° C., the reaction pressure is 0.5-101 kPa, and the reaction time is 7-10 hours;

[0058] Step (3): 15-25 parts by weight of the grafted tackifying resin (Cx-g-MA) obtained in step (1) is further blended with 50-70 parts by weight of P (MMA-co-GMA) obtained in step (2) and 15-25 parts by weight of lactic acid oligomer to obtain the modified tackifying resin. The reaction temperature is 160-190° C., the reaction pressure is 0.5-101 kPa, and the reaction time is 1-3 hours.

[0059] In some more specific embodiments, the method for preparing the modified tackifying resin comprises the following steps:

[0060] Step (1): melt-blending 83-95 parts by weight of tackifying resin Cx, 5-17 parts by weight of methacrylic acid MA, and 0.1-1.2 parts by weight of dicumyl peroxide to form a grafted tackifying resin Cx-g-MA, the reaction temperature being 110-135° C. and the reaction time being 6-9 minutes;

[0061] Step (2): 25-30 parts by weight of methyl methacrylate MMA, 25-30 parts by weight of glycidyl methacrylate GMA, 40-50 parts by weight of N,N-dimethylformamide DMF, and 0.2-0.5 parts by weight of azobisisobutyronitrile AIBN are mixed as initiators to carry out polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature is 68-75° C., the reaction pressure is 0.5-101 kPa, and the reaction time is 7.5-10 hours;

[0062] Step (3): 18-23 parts by weight of the grafted tackifying resin Cx-g-MA obtained in step (1) is further reacted with 54-64 parts by weight of P(MMA-co-GMA) obtained in step (2) and 18-23 parts by weight of lactic acid oligomers to obtain the modified tackifying resin, the reaction temperature is 165-185°C, and the reaction time is 1.5-3.5 hours.

[0063] The modified polylactic acid fiber of the present invention is g After sufficient storage time (40°C, 50RH%), the change rate of tensile strength before and after storage is generally less than 10%; wherein the storage time is not limited; however, generally speaking, the time is ≥ 180 days.

[0064] Another aspect of the embodiments of the present invention further provides a method for preparing the aforementioned modified polylactic acid fiber, which comprises:

[0065] The modified polylactic acid fiber is prepared by blending polylactic acid, modified tackifying resin and tackifying resin, granulating, melt spinning and heat drawing.

[0066] In some preferred embodiments, the extrusion temperature used in the blending and granulation is 160-220° C. and the screw speed is 20-70 rpm.

[0067] Furthermore, the extrusion temperature used in the blending and granulation is 180-200° C. and the screw speed is 30-50 rpm.

[0068] In some preferred embodiments, the spinning temperature used in the melt spinning is 200-250° C. and the spinning rate is 1000-3000 m / min.

[0069] Furthermore, the spinning temperature used in the melt spinning is 210-230° C., and the spinning rate is 1500-2500 m / min.

[0070] In some preferred embodiments, the melt spinning further comprises: spinning each raw material through a spinneret hole of a melt spinning spinneret.

[0071] Furthermore, the spinneret holes of the melt spinning spinneret are circular in cross section, wherein the diameter of the circular cross section is not specifically limited and can be selected as needed.

[0072] In some preferred embodiments, the heat stretching treatment uses a stretching temperature of 75-145° C. and a stretching multiple of 2.8-5.7 times.

[0073] Furthermore, the heat stretching treatment uses a stretching temperature of 90-130° C. and a stretching multiple of 3.2-4.9 times.

[0074] In some preferred embodiments, the raw materials polylactic acid, modified tackifying resin and tackifying resin are dried before blending and granulation, and the drying temperature is 90-98° C. and the drying time is 5-10 hours.

[0075] Another aspect of the embodiments of the present invention further provides the use of the aforementioned modified polylactic acid fiber in textile materials.

[0076] The present invention will be described in detail below by way of examples. In the following examples and comparative examples:

[0077] (1) Glass transition temperature was measured by differential scanning calorimetry (DSC);

[0078] (2) Mechanical properties (including tensile strength, elongation at break, and modulus) were measured using a universal tensile testing machine (refer to the national standard GB / T 14344);

[0079] (3) polylactic acid, tackifying resin, methacrylic acid, and methyl methacrylate are all commercially available. The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0080] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0081] Example 1

[0082] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0083] (1) 85 parts by weight of C5 tackifier resin, 15 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 120° C., the reaction time was 7 min, and a grafted tackifier resin with a grafting ratio of 34% was obtained;

[0084] (2) 30 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 40 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 70° C., the reaction pressure was 2 kPa, and the reaction time was 8 hours;

[0085] (3) 20 parts by weight of the grafted tackifying resin was further blended with 20 parts by weight of lactic acid oligomer and 60 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin. The reaction temperature was 160° C., the reaction pressure was 2 kPa, and the reaction time was 2 h. The modified tackifying resin was obtained. The NMR spectrum is shown in FIG. Figure 1 , indicating that the preparation was successful;

[0086] (4) Take polylactic acid (PLA) with a weight average molecular weight of 200,000, and a molar content of L optical isomer in PLA of 98%; a C5 tackifying resin with a weight average molecular weight of 1200; and a modified tackifying resin with a weight average molecular weight of 80,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 84 parts of polylactic acid, 8 parts of tackifying resin, and 8 parts of modified tackifying resin; mechanically mix according to this ratio, and hot air dry the blended particles at a drying temperature of 95±2°C, a drying time of 8 hours, and a water content of 42ppm;

[0087] (5) The dried blend was extruded and spun through a conventional melt spinning device, and the shape of the spinneret hole was circular; the spinning temperature was 230°C, the spinning speed was 2000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 3.6 times, to obtain modified polylactic acid fibers. The fibers were placed in a constant temperature and humidity chamber at 40°C and 50RH% for 180 days of stable treatment, and the performance of the modified polylactic acid fibers before and after 180 days of stable treatment was tested, and the test results are shown in Table 1. Figure 2 This is a diagram of the mechanical properties of the prepared modified polylactic acid fiber before and after aging. Figure 3This is a scanning electron microscope image of the insoluble matter obtained after Soxhlet extraction of modified polylactic acid fiber using chloroform solvent; polylactic acid can be dissolved in chloroform, while modified tackifying resin cannot; therefore, the microfiber structure in the scanning electron microscope image should be the undissolved modified tackifying resin. It can be inferred that a three-dimensional network structure composed of polylactic acid, modified tackifying resin and tackifying resin is formed in the modified polylactic acid fiber.

[0088] Example 2

[0089] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0090] (1) 95 parts by weight of C5 tackifier resin, 5 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 120° C., the reaction time was 10 min, and the molar grafting ratio of the grafted tackifier resin was 43%;

[0091] (2) 30 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 60 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 70° C., the reaction pressure was 2 kPa and the reaction time was 8 hours;

[0092] (3) 20 parts by weight of the grafted tackifying resin is further blended with 20 parts by weight of lactic acid oligomer and 60 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2 h;

[0093] (4) Take polylactic acid (PLA) with a weight average molecular weight of 250,000, and a molar content of L optical isomer in PLA of 97%; a C5 tackifying resin with a weight average molecular weight of 2000; and a modified tackifying resin with a weight average molecular weight of 80,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 82 parts of polylactic acid, 10 parts of tackifying resin, and 8 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 7 hours, and the water content is 48 ppm;

[0094] (5) The dried blend was extruded and spun through a conventional melt spinning device, and the shape of the spinneret hole was circular; the spinning temperature was 240°C, the spinning speed was 2000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 3.9 times, to obtain modified polylactic acid fibers. The fibers were placed in a constant temperature and humidity chamber at 40°C and 50RH% for 180 days of stable treatment, and the performance of the modified polylactic acid fibers before and after 180 days of stable treatment was tested, and the test results are shown in Table 1.

[0095] Example 3

[0096] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0097] (1) 95 parts by weight of C5 tackifier resin, 5 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 120° C., the reaction time was 10 min, and the molar grafting ratio of the grafted tackifier resin was 43%;

[0098] (2) 25 parts by weight of methyl methacrylate (MMA) and 25 parts by weight of glycidyl methacrylate (GMA), 50 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 70° C., the reaction pressure was 2 kPa, and the reaction time was 9 hours;

[0099] (3) 18 parts by weight of the grafted tackifying resin is further blended with 18 parts by weight of lactic acid oligomer and 64 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2.5 h;

[0100] (4) Take polylactic acid (PLA) with a weight average molecular weight of 230,000, and a molar content of L optical isomer in PLA of 96%; a C5 tackifier resin with a weight average molecular weight of 1600; a modified tackifier resin with a weight average molecular weight of 100,000, wherein the molar grafting ratio of the grafted tackifier resin is 40%; wherein the weight parts of each component in 100 parts by weight of the blend are: 80 parts of polylactic acid, 10 parts of tackifier resin, and 10 parts of modified tackifier resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 8 hours, and the water content is 50 ppm;

[0101] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 235°C, the spinning speed was 2000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 4.3 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0102] Example 4

[0103] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0104] (1) 85 parts by weight of C5 tackifier resin, 15 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 110° C., the reaction time was 6 min, and the molar grafting ratio of the grafted tackifier resin was 25%;

[0105] (2) 25 parts by weight of methyl methacrylate (MMA) and 25 parts by weight of glycidyl methacrylate (GMA), 50 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 70° C., the reaction pressure was 2 kPa, and the reaction time was 9 hours;

[0106] (3) 18 parts by weight of the grafted tackifying resin is further blended with 18 parts by weight of lactic acid oligomer and 64 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2.5 h;

[0107] (4) Take polylactic acid (PLA) with a weight average molecular weight of 250,000, and a molar content of L optical isomer in PLA of 99%; a C5 tackifying resin with a weight average molecular weight of 600; and a modified tackifying resin with a weight average molecular weight of 100,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 75 parts of polylactic acid, 15 parts of tackifying resin, and 10 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 7 hours, and the water content is 40 ppm;

[0108] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 210°C, the spinning speed was 3000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 3.5 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0109] Example 5

[0110] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0111] (1) 96 parts by weight of C5 tackifier resin, 4 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 140° C., the reaction time was 12 min, and the molar grafting ratio of the grafted tackifier resin was 70%;

[0112] (2) 30 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 40 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 70° C., the reaction pressure was 2 kPa, and the reaction time was 8 hours;

[0113] (3) 25 parts by weight of the grafted tackifying resin is further blended with 25 parts by weight of lactic acid oligomer and 50 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2 h;

[0114] (4) Take polylactic acid (PLA) with a weight average molecular weight of 250,000, and a molar content of L optical isomer in PLA of 95%; a C5 tackifying resin with a weight average molecular weight of 8,000; and a modified tackifying resin with a weight average molecular weight of 60,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 85 parts of polylactic acid, 5 parts of tackifying resin, and 10 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 10 hours, and the water content is 38 ppm;

[0115] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 245°C, the spinning speed was 3000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 3.2 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0116] Example 6

[0117] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0118] (1) 85 parts by weight of C5 tackifier resin, 15 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 110° C., the reaction time was 7 min, and the molar grafting ratio of the grafted tackifier resin was 30%;

[0119] (2) 30 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 40 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 70° C., the reaction pressure was 2 kPa and the reaction time was 8 hours;

[0120] (3) 18 parts by weight of the grafted tackifying resin is further blended with 18 parts by weight of lactic acid oligomer and 64 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2 h;

[0121] (4) Take polylactic acid (PLA) with a weight average molecular weight of 80,000, and a molar content of L optical isomer in PLA of 99%; a C5 tackifying resin with a weight average molecular weight of 1000; and a modified tackifying resin with a weight average molecular weight of 100,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 95 parts of polylactic acid, 2 parts of tackifying resin, and 3 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 10 hours, and the water content is 38 ppm;

[0122] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 225°C, the spinning speed was 2000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 4.9 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0123] Example 7

[0124] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0125] (1) 92 parts by weight of C5 tackifier resin, 8 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 130° C., the reaction time was 10 min, and the molar grafting ratio of the grafted tackifier resin was 50%;

[0126] (2) 40 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 30 parts by weight of N,N-dimethylformamide (DMF), and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 65° C., the reaction pressure was 2 kPa, and the reaction time was 7 hours;

[0127] (3) 20 parts by weight of the grafted tackifying resin is further blended with 20 parts by weight of lactic acid oligomer and 60 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2 h;

[0128] (4) Take polylactic acid (PLA) with a weight average molecular weight of 80,000, and a molar content of L optical isomer in PLA of 99%; a tackifying resin with a weight average molecular weight of 4,000; and a modified tackifying resin with a weight average molecular weight of 80,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 98 parts of polylactic acid, 1 part of tackifying resin, and 1 part of modified tackifying resin; the blend obtained by melt extrusion of the combination is hot-air dried at a drying temperature of 94±2°C for 8 hours, and the water content is 52 ppm;

[0129] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 240°C, the spinning speed was 1200 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 4.5 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0130] Example 8

[0131] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0132] (1) 95 parts by weight of C5 tackifier resin, 5 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 120° C., the reaction time was 10 min, and the molar grafting ratio of the grafted tackifier resin was 43%;

[0133] (2) 35 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 45 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 75° C., the reaction pressure was 2 kPa, and the reaction time was 8 hours;

[0134] (3) 18 parts by weight of the grafted tackifying resin is further blended with 18 parts by weight of lactic acid oligomer and 64 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2 h;

[0135] (4) Take polylactic acid (PLA) with a weight average molecular weight of 500,000, and a molar content of L optical isomer in PLA of 85%; C9 cold polymerization tackifying resin with a weight average molecular weight of 2000; and modified tackifying resin with a weight average molecular weight of 100,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 90 parts of polylactic acid, 5 parts of tackifying resin, and 5 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 9 hours, and the water content is 58 ppm;

[0136] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 250°C, the spinning speed was 1000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 4.2 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0137] Example 9

[0138] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0139] (1) 96 parts by weight of C5 tackifier resin, 4 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 140° C., the reaction time was 10 min, and the molar grafting ratio of the grafted tackifier resin was 64%;

[0140] (2) 30 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 40 parts by weight of N,N-dimethylformamide (DMF) and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 65° C., the reaction pressure was 2 kPa, and the reaction time was 12 hours;

[0141] (3) 15 parts by weight of the grafted tackifying resin is further blended with 15 parts by weight of a lactic acid oligomer and 70 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 2 h;

[0142] (4) Take polylactic acid (PLA) with a weight average molecular weight of 500,000, and a molar content of L optical isomer in PLA of 90%; a terpene resin with a weight average molecular weight of 5,000; and a modified tackifying resin with a weight average molecular weight of 120,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 80 parts of polylactic acid, 10 parts of terpene resin, and 10 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 10 hours, and the water content is 53 ppm;

[0143] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 240°C, the spinning speed was 1000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 5.5 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0144] Example 10

[0145] This embodiment is intended to illustrate the modified polylactic acid fiber prepared by the composition and method of the present invention.

[0146] (1) 82 parts by weight of C5 tackifier resin, 18 parts by weight of methacrylic acid (MA), and 0.8 parts by weight of dicumyl peroxide were melt-blended to form a tackifier resin having a carboxylic acid group, the reaction temperature was 110° C., the reaction time was 5 min, and the molar grafting ratio of the grafted tackifier resin was 21%;

[0147] (2) 33 parts by weight of methyl methacrylate (MMA) and 30 parts by weight of glycidyl methacrylate (GMA), 37 parts by weight of N,N-dimethylformamide (DMF), and 0.2 parts by weight of azobisisobutyronitrile were mixed as catalysts for polymerization reaction to form poly(methyl methacrylate-co-glycidyl methacrylate) P(MMA-co-GMA), the reaction temperature was 75° C., the reaction pressure was 2 kPa, and the reaction time was 10 hours;

[0148] (3) 30 parts by weight of the grafted tackifying resin is further blended with 30 parts by weight of lactic acid oligomer and 40 parts by weight of poly(methyl methacrylate-co-glycidyl methacrylate) to obtain a modified tackifying resin, the reaction temperature is 160° C., the reaction pressure is 2 kPa, and the reaction time is 1.5 h;

[0149] (4) Take polylactic acid (PLA) with a weight average molecular weight of 80,000, and a molar content of L optical isomer in PLA of 95%; a C5 / C9 copolymer tackifying resin with a weight average molecular weight of 20,000; and a modified tackifying resin with a weight average molecular weight of 20,000; wherein the weight parts of each component in 100 parts by weight of the blend are: 85 parts of polylactic acid, 10 parts of tackifying resin, and 5 parts of modified tackifying resin; the blend obtained by melt extrusion of the composition is hot-air dried at a drying temperature of 94±2°C for 8 hours, and the water content is 48 ppm;

[0150] (5) The dried blend was extruded and spun through a conventional melt spinning device, the spinneret hole was circular in shape; the spinning temperature was 220°C, the spinning speed was 3000 m / min, and the blended long fibers were wound up; finally, the blended long fibers were stretched and heat-set, the stretching temperature was 95°C, and the stretching ratio was 3.2 times, to obtain modified bio-based polymer fibers. The properties of the modified bio-based polymer fibers were tested, and the test results are shown in Table 1.

[0151] Comparative Example 1

[0152] The method of Example 2 was followed, except that "82 parts of polylactic acid" was replaced by "32 parts" and "8 parts of modified tackifying resin" was replaced by "50 parts". The test results are shown in Table 1.

[0153] Comparative Example 2

[0154] The method of Example 2 was followed, except that no modified tackifying resin was added. The test results are shown in Table 1.

[0155] Comparative Example 3

[0156] The method of Example 7 was followed, except that the modified tackifying resin and tackifying resin were not added. The test results are shown in Table 1.

[0157] Comparative Example 4

[0158] The method is the same as in Example 2, except that the "grafted tackifying resin" replaces the "modified tackifying resin". The test results are shown in Table 1.

[0159] Comparative Example 5

[0160] The method is the same as Example 2, except that "grafted tackifying resin, P(MMA-co-GMA), lactic acid oligomer" (not reacted first, but added directly) replaces "modified tackifying resin". The test results are shown in Table 1.

[0161] Comparative Example 6

[0162] The method is the same as in Example 2, except that the molecular weight of the polylactic acid is 50,000. The test results are shown in Table 1.

[0163] Comparative Example 7

[0164] The method is the same as that of Example 2, except that the spinning temperature is 280° C. The test results are shown in Table 1.

[0165] Comparative Example 8

[0166] The method is the same as in Example 2, except that the spinning rate is 5000 m / min. The test results are shown in Table 1.

[0167] Comparative Example 9

[0168] The method is the same as in Example 2, except that the drawing temperature is 150° C. The test results are shown in Table 1.

[0169] Comparative Example 10

[0170] The method is the same as in Example 2, except that the drafting ratio is 7. The test results are shown in Table 1.

[0171] Table 1 Performance test results of products of Examples 1-10 and Comparative Examples 1-10

[0172]

[0173] As can be seen from Table 1, the modified polylactic acid fiber of the present invention has good comprehensive properties, breaking through the performance bottleneck of conventional polylactic acid fiber that is prone to physical aging and leads to reduced strength, thereby fully meeting the use requirements and can be applied to the fields of textile materials and the like.

[0174] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0175] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A modified polylactic acid fiber, characterized in that: The raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 70-98 parts of polylactic acid, 1-15 parts of modified tackifying resin and 1-15 parts of tackifying resin; The modified tackifying resin is prepared by grafting tackifying resin with methacrylic acid to form a grafted tackifying resin, and then reacting with poly (methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer.

2. The modified polylactic acid fiber according to claim 1, characterized in that: The raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 80-90 parts of polylactic acid, 5-10 parts of modified tackifying resin and 5-10 parts of tackifying resin; And / or, the weight average molecular weight of the polylactic acid is 80,000-500,000, and the molar content of the L optical isomer in the polylactic acid is 85-99%; And / or, the weight average molecular weight of the modified tackifying resin is 20,000-120,000; And / or, the tackifying resin includes any one or more combinations of C5 tackifying resin, C5 hydrogenated tackifying resin, C9 hydrogenated tackifying resin, C9 cold-polymerized tackifying resin, C9 hot-polymerized tackifying resin, C5 / C9 copolymerized tackifying resin, terpene resin, and rosin ester; And / or, the weight average molecular weight of the tackifying resin is 300-10000. And / or, the molar grafting ratio of the grafted tackifying resin is 20-70%.

3. The modified polylactic acid fiber according to claim 2, characterized in that: The raw materials for preparing the modified polylactic acid fiber include the following components calculated by weight: 80-86 parts of polylactic acid, 8-10 parts of modified tackifying resin and 8-10 parts of tackifying resin; And / or, the weight average molecular weight of the polylactic acid is 150,000-350,000, and the molar content of the L optical isomer in the polylactic acid is 94-98%; And / or, the weight average molecular weight of the modified tackifying resin is 40,000-80,000; And / or, the weight average molecular weight of the grafted tackifying resin is 1000-3000, and the molar grafting ratio is 30-55%.

4. The modified polylactic acid fiber according to claim 1, characterized in that: The modified polylactic acid fiber is treated at 40°C and 50RH% for 180 days, and the strength decay is less than 10%; And / or, the modified polylactic acid fiber has a tensile strength of 3.2-5.6 cN / dtex and an elongation at break of 18%-30%.

5. The modified polylactic acid fiber according to claim 1, characterized in that: The preparation method of the modified tackifying resin comprises: Allowing a first mixed reaction system containing at least a tackifying resin and methacrylic acid to undergo a first reaction at 100-150° C. for 4-12 minutes to obtain a grafted tackifying resin; Under the conditions of a reaction pressure of 0.5-101 KPa and a temperature of 60-80° C., a second mixed reaction system comprising methyl methacrylate, glycidyl methacrylate, and a solvent is subjected to a second reaction for 6-12 hours to obtain poly(methyl methacrylate-co-glycidyl methacrylate); And, the grafted tackifying resin is subjected to a third reaction with poly(methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer under the conditions of a reaction pressure of 0.5-101 KPa and a temperature of 155-195° C. for 1-4 hours to obtain a modified tackifying resin.

6. The modified polylactic acid fiber according to claim 5, characterized in that: The mass ratio of the tackifying resin to methacrylic acid is 80-98:2-20; And / or, the mass ratio of methyl methacrylate, glycidyl methacrylate and solvent is 25-50:25-35:15-50; and / or, the mass ratio of the grafted tackifying resin, poly(methyl methacrylate-co-glycidyl methacrylate) and lactic acid oligomer is 15-30:40-70:15-30; and / or, the weight average molecular weight of the lactic acid oligomer is 1000-10000; and / or, the molecular weight of the poly(methyl methacrylate-co-glycidyl methacrylate) is 20,000-120,000; And / or, the solvent includes any one or more combinations of N,N-dimethylformamide, toluene, and water; And / or, the preparation method of the modified tackifying resin specifically comprises: subjecting a first mixed reaction system comprising a tackifying resin, methacrylic acid, and an initiator in a mass ratio of 80-98:2-20:0.1-1.2 to a first reaction at 100-150° C. for 4-12 min to obtain a grafted tackifying resin; wherein the initiator comprises dicumyl peroxide and / or dibenzoyl peroxide; And / or, the preparation method of the modified tackifying resin specifically comprises: under the conditions of a reaction pressure of 0.5-101 KPa and a temperature of 60-80°C, a second mixed reaction system comprising methyl methacrylate, glycidyl methacrylate, solvent, and initiator in a mass ratio of 25-40:25-30:30-50:0.2-0.5 is subjected to a second reaction for 7-10 hours to obtain poly(methyl methacrylate-co-glycidyl methacrylate); wherein the initiator comprises any one or more combinations of azobisisobutyronitrile, azobiscyanovaleric acid, and azobisisoheptylonitrile.

7. The method for preparing the modified polylactic acid fiber according to any one of claims 1 to 6, characterized in that: include: The modified polylactic acid fiber is prepared by blending polylactic acid, modified tackifying resin and tackifying resin, granulating, melt spinning and heat drawing.

8. The preparation method according to claim 7, characterized in that: The extrusion temperature used in the blending and granulation is 160-220°C and the screw speed is 20-70rpm; And / or, the spinning temperature used in the melt spinning is 200-250° C. and the spinning rate is 1000-3000 m / min; And / or, the heat stretching treatment adopts a stretching temperature of 75-145° C. and a stretching multiple of 2.8-5.7 times.

9. The preparation method according to claim 8, characterized in that: The extrusion temperature used in the blending and granulation is 180-200°C and the screw speed is 30-50rpm; And / or, the spinning temperature used in the melt spinning is 210-230° C., and the spinning rate is 1500-2500 m / min; and / or, the drawing temperature used in the hot drawing treatment is 90-130° C., and the drawing ratio is 3.2-4.9 times.

10. Use of the modified polylactic acid fiber according to any one of claims 1 to 6 in the preparation of textile materials.

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