A modified polylactic acid and its preparation method and application

Abstract

This application discloses a modified polylactic acid, its preparation method, and its application, relating to the field of polymer materials technology. The structural formula of the modified polylactic acid is as follows: #imgabs0#, where m is an integer from 2 to 10, and n is an integer from 30 to 100. The modified polylactic acid provided in the embodiments of this application exhibits excellent 3D printability, mechanical properties, and rapid degradation, and has broad application prospects.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a modified polylactic acid and a preparation method and application thereof. Background Art

[0002] 3D printing technology has been widely used in many fields such as industrial manufacturing, medical health, and consumer electronics due to its short processing cycle and ability to accurately form various complex structures.

[0003] In this field, polylactic acid (PLA) has become the mainstream material due to its easy processing, environmental friendliness, and biocompatibility. PLA has relatively excellent mechanical strength (greater than 40 MPa) and good dimensional stability, properties that are primarily due to its high molecular weight (60,000 to 100,000). However, high-molecular-weight PLA suffers from a slow degradation rate, requiring harsh conditions such as composting conditions and temperatures exceeding 60°C for degradation within 2 to 3 months. In contrast, low-molecular-weight PLA (number-average molecular weight less than 5 kilodaltons) has a faster degradation rate and is easier and less expensive to synthesize, making it more promising in certain applications.

[0004] However, low molecular weight PLA has poor mechanical properties and is generally difficult to mold, which limits its application. Summary of the Invention

[0005] In view of this, the present application provides a modified polylactic acid and a preparation method and application thereof.

[0006] The embodiments of the present application are implemented as follows. In a first aspect, the embodiments of the present application provide a modified polylactic acid, the structural formula of the modified polylactic acid is shown below:

[0007] ;

[0008] wherein m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0009] In a second aspect, the present invention also provides a method for preparing modified polylactic acid, comprising the following steps:

[0010] A first compound is provided, wherein the structural formula of the first compound is shown below: , wherein n is selected from an integer of 20 to 60;

[0011] A second compound is provided, wherein the structural formula of the second compound is shown below: ;

[0012] Providing polyetheramine D-400, mixing with the first compound and the second compound, and reacting to obtain modified polylactic acid.

[0013] Alternatively, in some embodiments of the present application, the method for preparing the first compound comprises:

[0014] Providing a dihydroxy-terminated polylactic acid dispersion, wherein the dihydroxy-terminated polylactic acid dispersion comprises dihydroxy-terminated polylactic acid and a first solvent;

[0015] Providing a p-carboxybenzaldehyde dispersion, wherein the p-carboxybenzaldehyde dispersion comprises p-carboxybenzaldehyde and a second solvent;

[0016] The dihydroxy-terminated polylactic acid dispersion and the p-carboxybenzaldehyde dispersion are mixed and reacted to obtain a first compound.

[0017] Optionally, in some embodiments of the present application, the first solvent and the second solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; and / or,

[0018] In the dihydroxy-terminated polylactic acid dispersion, the molar concentration of the dihydroxy-terminated polylactic acid is 0.01 mol / L to 0.1 mol / L; and / or,

[0019] The dihydroxy-terminated polylactic acid dispersion further comprises a catalyst; the catalyst comprises 4-dimethylaminopyridine; and / or,

[0020] The dihydroxy-terminated polylactic acid dispersion further includes a first water absorbing agent; the first water absorbing agent includes dicyclohexylcarbodiimide; and / or,

[0021] In the p-carboxybenzaldehyde dispersion, the molar concentration of p-carboxybenzaldehyde is 1 mol / L to 10 mol / L; and / or,

[0022] The molar ratio of the dihydroxy-terminated polylactic acid to the p-carboxybenzaldehyde is 1:(1-5); and / or,

[0023] The reaction temperature of the bishydroxyl-terminated polylactic acid and the p-carboxybenzaldehyde is 20° C. to 30° C.; the reaction time of the bishydroxyl-terminated polylactic acid and the p-carboxybenzaldehyde is 20 h to 30 h.

[0024] Optionally, in some embodiments of the present application, the method for preparing the second compound comprises:

[0025] An intermediate product dispersion is provided, wherein the intermediate product dispersion comprises an intermediate product and a third solvent, and the structural formula of the intermediate product is shown below: ;

[0026] Providing a butanediamine dispersion, wherein the butanediamine dispersion comprises butanediamine and a fourth solvent;

[0027] The intermediate product dispersion and the butanediamine dispersion are mixed and reacted to obtain a second compound.

[0028] Alternatively, in some embodiments of the present application, the method for preparing the intermediate product comprises:

[0029] Providing an acryloyl chloride dispersion, wherein the acryloyl chloride dispersion comprises acryloyl chloride and a fifth solvent;

[0030] Providing a thiocarbamate dispersion, wherein the thiocarbamate dispersion comprises thiocarbamate and a sixth solvent;

[0031] The acryloyl chloride dispersion and the oxaloyl dihydrazide dispersion are mixed and reacted to obtain an intermediate product.

[0032] Optionally, in some embodiments of the present application, the fifth solvent and the sixth solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; and / or,

[0033] In the acryloyl chloride dispersion, the molar concentration of acryloyl chloride is 1 mol / L to 5 mol / L; and / or,

[0034] The acryloyl chloride dispersion also includes an acid coating agent; the acid coating agent includes one or more of triethylamine and pyridine; and / or,

[0035] In the oxalohydrazide dispersion, the molar concentration of the oxalohydrazide is 0.1 mol / L to 1 mol / L; and / or,

[0036] The molar ratio of the acryloyl chloride to the oxaloylhydrazide is 1:(1-5); and / or,

[0037] The reaction temperature of the acryloyl chloride and the oxaloyl hydrazide is 0° C.; the reaction time of the acryloyl chloride and the oxaloyl hydrazide is 1 h to 5 h.

[0038] Optionally, in some embodiments of the present application, the third solvent and the fourth solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; and / or,

[0039] In the intermediate product dispersion, the molar concentration of the intermediate product is 0.1 mol / L to 1 mol / L; and / or,

[0040] In the dibutylene glycol dispersion, the molar concentration of dibutylene glycol is 1 mol / L to 5 mol / L; and / or,

[0041] The molar ratio of the intermediate product to the butanediamine is (1-5):1; and / or,

[0042] The reaction temperature of the intermediate product and the butanediamine is 50° C. to 100° C.; the reaction time of the intermediate product and the butanediamine is 10 h to 20 h.

[0043] Optionally, in some embodiments of the present application, the mixing of the polyetheramine D-400 with the first compound and the second compound comprises: providing a first compound dispersion, wherein the first compound dispersion comprises the first compound and a seventh solvent; providing a mixture dispersion, wherein the mixture dispersion comprises a mixture and an eighth solvent, wherein the mixture comprises the polyetheramine D-400 and the second compound; mixing the first compound dispersion and the mixture dispersion, reacting, to obtain modified polylactic acid; wherein,

[0044] The seventh solvent and the eighth solvent are each independently selected from one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, and acetone; and / or,

[0045] In the first compound dispersion, the molar concentration of the first compound is 0.01 mol / L to 0.1 mol / L; and / or,

[0046] The first compound dispersion further includes a second water absorbing agent; and / or,

[0047] The second water absorbing agent includes dicyclohexylcarbodiimide; and / or,

[0048] In the mixture dispersion, the molar concentration of the second compound is 0.1 mol / L to 1 mol / L; and / or,

[0049] In the mixture dispersion, the molar concentration of the polyetheramine D-400 is 0.01 mol / L to 0.1 mol / L; and / or,

[0050] The molar ratio of the first compound, the second compound and the polyetheramine D-400 is (1-5): (1-2): (0.1-1); and / or,

[0051] The reaction temperature of the first compound, the second compound and the polyetheramine D-400 is 20° C. to 50° C.; the reaction time of the first compound, the second compound and the polyetheramine D-400 is 10 h to 20 h; and / or,

[0052] The structural formula of the modified polylactic acid is shown below:

[0053] ; wherein, m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0054] In a third aspect, the embodiments of the present application further provide an application of the above-mentioned modified polylactic acid, or the modified polylactic acid prepared by the above-mentioned preparation method in 3D printing.

[0055] The modified polylactic acid provided in the embodiments of the present application has excellent 3D printing processing performance, mechanical properties and rapid degradation ability, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0057] Figure 1 This is a flow chart of a method for preparing modified polylactic acid provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0059] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of a device in actual use or operation, specifically in the drawing directions of the accompanying drawings; whereas "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "including" means "including but not limited to." Terms such as first, second, and third are used solely for designation and do not impose numerical requirements or establish a sequential order.

[0060] In this application, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0061] In this application, "at least one" means one or more, and "plurality" means two or more. "One or more," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or plural.

[0062] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0063] The structural formulas and molecular weights of some chemical reagents used in this application are described below:

[0064] Dihydroxy terminated polylactic acid (dihydroxy PLA): , n is an integer from 30 to 100, number average molecular weight = 5000, purchased from Hubei Yamaide Biopharmaceutical Co., Ltd.;

[0065] p-Carboxybenzaldehyde: , molecular weight = 150.13;

[0066] p-Carboxybenzaldehyde: , molecular weight = 122.17;

[0067] Dicyclohexylcarbodiimide: , molecular weight = 206.33;

[0068] Acryloyl chloride: , molecular weight = 90.5;

[0069] Oxaloyldihydrazide: , molecular weight = 118.09;

[0070] Butanediamine: , molecular weight = 88.15;

[0071] Polyetheramine D-400: , where m is an integer from 2 to 10, and the number average molecular weight is 400;

[0072] Triethylamine: Molecular weight = 101.19.

[0073] The technical solution of this application is as follows:

[0074] In a first aspect, an embodiment of the present application provides a modified polylactic acid, the structural formula of the modified polylactic acid is shown below:

[0075] ;

[0076] wherein m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0077] It is understood that m and n represent the degree of polymerization respectively.

[0078] The modified polylactic acid provided in the embodiments of the present application has excellent 3D printing processing performance, mechanical properties and rapid degradation ability, and has broad application prospects.

[0079] Second, see Figure 1 The present invention provides a method for preparing modified polylactic acid, comprising the following steps:

[0080] Step S11: providing a first compound, wherein the structural formula of the first compound is shown below: , wherein n is selected from an integer of 20 to 60;

[0081] Step S12: providing a second compound, wherein the structural formula of the second compound is as shown below: ;

[0082] Step S13: providing polyetheramine D-400, mixing it with the first compound and the second compound, and reacting them to obtain modified polylactic acid.

[0083] The preparation method of modified polylactic acid provided in the present application uses low-molecular-weight polylactic acid as the basic raw material, uses dynamic imine bonds as connection points for chain extension, and introduces quadruple hydrogen bonds between molecules to obtain supramolecular effects. These bonds serve as dynamic sacrificial bonds to impart excellent mechanical toughness to the polylactic acid. At the same time, a small amount of long-chain polyetheramine is used for chain extension to regulate the crystallinity and melt fluidity of the polylactic acid, thereby further improving the impact resistance and 3D printing performance of the polylactic acid material. In addition, the imine bond, as an acid-base sensitive dynamic covalent bond, can regenerate low-molecular-weight polylactic acid fragments and chain extender molecules under acidic treatment, ensuring its rapid biodegradability.

[0084] In the step S11:

[0085] In some embodiments, the method for preparing the first compound comprises:

[0086] Step S111, providing a dihydroxy-terminated polylactic acid dispersion, wherein the dihydroxy-terminated polylactic acid dispersion comprises dihydroxy-terminated polylactic acid and a first solvent;

[0087] Step S112: providing a p-carboxybenzaldehyde dispersion, wherein the p-carboxybenzaldehyde dispersion comprises p-carboxybenzaldehyde and a second solvent;

[0088] Step S113: mixing the dihydroxy-terminated polylactic acid dispersion and the p-carboxybenzaldehyde dispersion, and reacting them to obtain a first compound.

[0089] In some embodiments, the first solvent and the second solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether.

[0090] In some embodiments, the molar concentration of the dihydroxy-terminated polylactic acid in the dihydroxy-terminated polylactic acid dispersion is 0.01 mol / L to 0.1 mol / L, for example, 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, or a range between any two of the foregoing values. Within this molar concentration range, the dihydroxy-terminated polylactic acid is facilitated to be uniformly dissolved and dispersed.

[0091] In some embodiments, the dihydroxy-terminated polylactic acid dispersion further includes a catalyst.

[0092] Furthermore, the catalyst includes 4-dimethylaminopyridine (DMAP).

[0093] In some embodiments, the dihydroxy-terminated polylactic acid dispersion further includes a first water absorbing agent.

[0094] Furthermore, the first water absorbing agent includes dicyclohexylcarbodiimide (DCC).

[0095] In some embodiments, the p-carboxybenzaldehyde dispersion has a molar concentration of 1 mol / L to 10 mol / L, for example, 1 mol / L, 2 mol / L, 4 mol / L, 6 mol / L, 8 mol / L, 10 mol / L, or a range between any two of the above values. Within the molar concentration range, the p-carboxybenzaldehyde is facilitated to be uniformly dissolved and dispersed.

[0096] In some embodiments, the molar ratio of the bis-hydroxy-terminated polylactic acid to the p-carboxybenzaldehyde is 1:(1-5), for example, 1:1, 1:2, 1:3, 1:4, 1:5, or a range between any two of the aforementioned ratios. Within this molar ratio range, the bis-hydroxy-terminated polylactic acid and p-carboxybenzaldehyde efficiently react to form the first compound, thereby increasing the yield of the first compound.

[0097] In some embodiments, the reaction temperature of the bis-hydroxyl-terminated polylactic acid and the p-carboxybenzaldehyde is 20° C. to 30° C., for example, 20° C., 22° C., 25° C., 28° C., 300° C., or a range between any two of the foregoing values; the reaction time of the bis-hydroxyl-terminated polylactic acid and the p-carboxybenzaldehyde is 20 h to 30 h, for example, 20 h, 24 h, 26 h, 28 h, 30 h, or a range between any two of the foregoing values. Thus, under the reaction conditions, the first compound is efficiently generated.

[0098] In some embodiments, the synthesis route of the reaction of the dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde to form the first compound is shown in the following formula:

[0099] .

[0100] In the step S12:

[0101] In some embodiments, the method for preparing the second compound comprises:

[0102] Step S121: providing an intermediate product dispersion liquid, wherein the intermediate product dispersion liquid includes the intermediate product and a third solvent, and the structural formula of the intermediate product is shown below: ;

[0103] Step S122, providing a butanediamine dispersion, wherein the butanediamine dispersion comprises butanediamine and a fourth solvent;

[0104] Step S123: mixing the intermediate product dispersion and the dibutylene diamine dispersion, and reacting them to obtain a second compound.

[0105] In some embodiments, the method for preparing the intermediate product comprises:

[0106] Step S1211: providing an acryloyl chloride dispersion, wherein the acryloyl chloride dispersion includes acryloyl chloride and a fifth solvent;

[0107] Step S1212: providing a thiocarbamate dispersion, wherein the thiocarbamate dispersion comprises thiocarbamate and a sixth solvent;

[0108] Step S1213: mixing the acryloyl chloride dispersion and the oxaloylhydrazide dispersion, and reacting them to obtain an intermediate product.

[0109] In some embodiments, the fifth solvent and the sixth solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether.

[0110] In some embodiments, the molar concentration of acryloyl chloride in the acryloyl chloride dispersion is 1 mol / L to 5 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, or a range between any two of the foregoing values. Within this molar concentration range, the acryloyl chloride is facilitated to be uniformly dissolved and dispersed.

[0111] In some embodiments, the acryloyl chloride dispersion further includes an acidifying agent.

[0112] Furthermore, the acid coating agent includes one or more of triethylamine and pyridine.

[0113] In some embodiments, the molar concentration of oxalohydrazide in the oxalohydrazide dispersion is 0.1 mol / L to 1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, or a range between any two of the above values. Within the molar concentration range, the uniform dissolution and dispersion of the oxalohydrazide is facilitated.

[0114] In some embodiments, the molar ratio of acryloyl chloride to oxaloyl hydrazide is 1:(1-5), for example, 1:1, 1:2, 1:3, 1:4, 1:5, or a range between any two of the above ratios. Within this molar ratio range, acryloyl chloride and oxaloyl hydrazide react efficiently to form an intermediate product, thereby increasing the yield of the intermediate product.

[0115] In some embodiments, the reaction temperature of the acryloyl chloride and the oxalohydrazide is 0° C.; the reaction time of the acryloyl chloride and the oxalohydrazide is 1 to 5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or a range between any two of the foregoing values. Thus, under the reaction conditions, the intermediate product is efficiently produced.

[0116] It should be noted that the reaction between the acryloyl chloride and the oxaloylhydrazide can be carried out in an ice bath.

[0117] In some embodiments, the synthesis route of the reaction between the acryloyl chloride and the oxaloylhydrazide to generate an intermediate product is shown below:

[0118] .

[0119] In some embodiments, the third solvent and the fourth solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether.

[0120] In some embodiments, the molar concentration of the intermediate product in the intermediate product dispersion is 0.1 mol / L to 1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, or a range between any two of the foregoing values. Within the molar concentration range, uniform dissolution and dispersion of the intermediate product is facilitated.

[0121] In some embodiments, the molar concentration of butanediamine in the butanediamine dispersion is 1 mol / L to 5 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, or a range between any two of the foregoing values. Within this molar concentration range, the butanediamine is facilitated to be uniformly dissolved and dispersed.

[0122] In some embodiments, the molar ratio of the intermediate product to the butanediamine is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, or a range between any two of the above ratios. Within this molar ratio range, the intermediate product and butanediamine react efficiently to form the second compound, thereby increasing the yield of the second compound.

[0123] In some embodiments, the reaction temperature of the intermediate product and the butanediamine is 50° C. to 100° C., for example, 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., or a range between any two of the foregoing values; and the reaction time of the intermediate product and the butanediamine is 10 h to 20 h, for example, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, or a range between any two of the foregoing values. Thus, under the reaction conditions, the second compound is efficiently produced.

[0124] In some embodiments, the synthesis route of the reaction between the intermediate product and the diamine to form the second compound is shown below:

[0125] .

[0126] In the step S13:

[0127] In some embodiments, the mixture of the polyetheramine D-400, the first compound, and the second compound comprises:

[0128] Step S131: providing a first compound dispersion, wherein the first compound dispersion includes the first compound and a seventh solvent;

[0129] Step S132, providing a mixture dispersion, wherein the mixture dispersion includes a mixture and an eighth solvent, and the mixture includes the polyetheramine D-400 and the second compound;

[0130] Step S133: mixing the first compound dispersion and the mixture dispersion, reacting them to obtain modified polylactic acid.

[0131] In some embodiments, the seventh solvent and the eighth solvent are each independently selected from one or more of N,N-dimethylformamide (DMF), N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, and acetone.

[0132] In some embodiments, the molar concentration of the first compound in the first compound dispersion is 0.01 mol / L to 0.1 mol / L, for example, 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, or a range between any two of the foregoing values. Within this molar concentration range, uniform dissolution and dispersion of the first compound is facilitated.

[0133] In some embodiments, the first compound dispersion further includes a second water absorbing agent.

[0134] Furthermore, the second water absorbing agent includes dicyclohexylcarbodiimide (DCC).

[0135] In some embodiments, the molar concentration of the second compound in the mixture dispersion is 0.1 mol / L to 1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, or a range between any two of the foregoing values. Within this molar concentration range, uniform dissolution and dispersion of the mixture is facilitated.

[0136] In some embodiments, the molar concentration of the polyetheramine D-400 in the mixture dispersion is 0.01 mol / L to 0.1 mol / L, for example, 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, or a range between any two of the foregoing values. Within this molar concentration range, uniform dissolution and dispersion of the mixture is facilitated.

[0137] In some embodiments, the molar ratio of the first compound, the second compound, and the polyetheramine D-400 is (1-5):(1-2):(0.1-1), for example, 1:1:0.1, 1:2:0.5, 2:1.5:0.4, 3:1.2:0.6, 4:0.8:0.8, or a range between any two of the above ratios. Within this molar ratio range, the first compound, the second compound, and the polyetheramine D-400 react efficiently to form modified polylactic acid, thereby increasing the yield of the modified polylactic acid.

[0138] In some embodiments, the reaction temperature of the first compound, the second compound, and the polyetheramine D-400 is 20°C to 50°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C; the reaction time of the first compound, the second compound, and the polyetheramine D-400 is 10 hours to 20 hours, for example, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, or a range between any two of the foregoing values. Thus, under the above reaction conditions, the modified polylactic acid is efficiently produced.

[0139] In some embodiments, the structural formula of the modified polylactic acid is shown below:

[0140] ;

[0141] wherein m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0142] It is understood that m and n represent the degree of polymerization respectively.

[0143] In a third aspect, the embodiments of the present application further provide applications of the modified polylactic acid or the modified polylactic acid prepared by the above-mentioned preparation method.

[0144] Specifically, the modified polylactic acid has excellent 3D printing processing performance, mechanical properties and rapid degradation ability, and can be applied to 3D printing.

[0145] The present application will be described in detail below through specific examples. The following examples are only some examples of the present application and are not limitations of the present application.

[0146] Example 1:

[0147] This embodiment provides a modified polylactic acid, the preparation method of which includes the following steps:

[0148] Step 1: Weigh 0.03 mol of dihydroxy-terminated polylactic acid, 0.5 g of 4-dimethylaminopyridine, 0.06 mol of dicyclohexylcarbodiimide and 600 mL of anhydrous tetrahydrofuran into a 1000 mL three-necked flask, introduce circulating nitrogen protection, and keep stirring at 25°C until the reactants are completely dissolved. Weigh 0.075 mol of p-carboxybenzaldehyde and dissolve it in 50 mL of anhydrous tetrahydrofuran, add it to the three-necked flask at 25°C, keep stirring and circulating nitrogen protection, and react at 25°C for 24 hours. After the reaction is completed, filter and remove the by-products generated by the absorption of water by the dicyclohexylcarbodiimide. The filtrate is rotary evaporated at 35°C to remove the tetrahydrofuran in the system. The precipitate after rotary evaporation is then rinsed with excess ethanol to remove the remaining p-carboxybenzaldehyde and 4-dimethylaminopyridine to obtain the first compound;

[0149] Step 2: Weigh 0.15 mol of acryloyl chloride, 0.1 mol of anhydrous triethylamine and 100 mL of anhydrous tetrahydrofuran into a 250 mL three-necked flask, start stirring, and introduce circulating nitrogen for protection. Then dissolve 0.05 mol of oxaloyl hydrazide in 80 mL of anhydrous tetrahydrofuran, and gradually drip the oxaloyl hydrazide / tetrahydrofuran solution into the three-necked flask through a constant pressure funnel under ice bath conditions. After the addition is completed, react for 2 hours under ice bath conditions and nitrogen protection, during which a white by-product (triethylamine hydrochloride) precipitates. After the reaction is completed, filter and remove the by-product triethylamine hydrochloride, and rotary evaporate the filtrate at 50 ° C to remove unreacted acryloyl chloride and residual tetrahydrofuran to obtain an intermediate product;

[0150] Step 3: Add 0.18 mol of diamine and 100 mL of anhydrous dioxane to a 250 mL three-necked flask, start stirring, and heat to 80°C. Then, take 0.03 mol of the intermediate product and dissolve it in 50 mL of anhydrous dioxane. At 80°C, gradually add it dropwise to the three-necked flask through a constant pressure funnel under nitrogen protection. After the addition is complete, react at 80°C for 12 hours. After the reaction is completed, remove the residual dioxane in the system by rotary evaporation at 70°C. Rinse with deionized water at room temperature to remove unreacted diamine to obtain the second compound.

[0151] Step 4: Add 0.02 mol of the first compound, 0.04 mol of dicyclohexylcarbodiimide, and 300 mL of anhydrous DMF to a 500 mL three-necked flask, start stirring, introduce nitrogen gas, heat to 30°C, and maintain stirring until the reactants are completely dissolved. Dissolve 0.019 mol of the second compound and 0.001 mol of polyetheramine D-400 in 50 mL of anhydrous DMF, pour the mixture into the three-necked flask, stir evenly, maintain nitrogen gas flow, and react at 30°C for 12 hours. During this time, byproducts generated by the absorption of water by the dicyclohexylcarbodiimide will precipitate. After the reaction is completed, filter out the byproducts generated by the absorption of water by the dicyclohexylcarbodiimide, pour the filtrate into excess methanol for precipitation, filter again, and dry the precipitate in a forced air drying oven at 60°C to obtain modified polylactic acid.

[0152] Example 2:

[0153] This embodiment is substantially the same as embodiment 1, except that the amounts of the substances used in step 4 are: 0.02 mol of the first compound, 0.018 mol of the second compound, and 0.002 mol of polyetheramine D-400.

[0154] Example 3:

[0155] This embodiment is substantially the same as embodiment 1, except that the amounts of the substances used in step 4 are: 0.02 mol of the first compound, 0.018 mol of the second compound, and 0.004 mol of polyetheramine D-400.

[0156] Example 4:

[0157] This embodiment is substantially the same as embodiment 1, except that the amounts of the substances used in step 4 are: 0.02 mol of the first compound, 0.018 mol of the second compound, and 0.008 mol of polyetheramine D-400.

[0158] Comparative Example:

[0159] This comparative example provides a modified polylactic acid, which is a commercially available polylactic acid for 3D printing (PLA L105, purchased from Total Cobien Ltd.).

[0160] The modified polylactic acid of Examples 1-4 and the modified polylactic acid of the comparative example were used to prepare tensile spline bars using the fused deposition modeling (FDM) technology in 3D printing. Specifically, the tensile spline dimensions were set according to GB / T1040.3-2006. A standard spline model of the polylactic acid was created using SolidWorks 3D modeling software. Printing was performed using a CR-5 (model) desktop 3D printer (Shenzhen Innovation 3D Technology Co., Ltd.) at a printing speed of 30 mm / s and a printing temperature of 180°C / 200°C (180°C for Examples 1-4 and 200°C for the comparative example). The layer height was set to 0.2 mm, resulting in tensile spline bars measuring 150 mm by 10 mm by 4 mm.

[0161] The melt flow properties, mechanical properties, crystallization properties, and biodegradability of the 3D printed specimens were tested. The test results are shown in Table 1.

[0162] Among them, the tensile performance test is carried out in accordance with the standard GB / T1040.3-2006, and the tensile rate is 20mm / min.

[0163] The melt index was determined in accordance with GB / T 3682.1-2018 “Plastics—Thermoplastics—Determination of melt mass-flow rate (MFR) and melt volume-flow rate (MVR)—Part 1: Standard method”. The test temperature was 190°C and the weight used was 2.1 kg.

[0164] Impact toughness is measured in accordance with standard T / GZZJ 08-2020, "Determination of simply supported beam impact properties of polylactic acid consumables for 3D printing." Heat deformation temperature is measured in accordance with standard GB / T 29284-2024.

[0165] The melting temperature was determined in accordance with GB / T 19466.3-2004.

[0166] Before composting, PLA was hydrolyzed under acidic conditions to generate low-molecular-weight PLA fragments, which were then tested for degradation performance. Specifically, PLA strips were placed in a hydrochloric acid solution (pH < 3), mechanically stirred at room temperature for 1 hour, filtered, and the precipitate rinsed with deionized water. The composting temperature was maintained at 56-60°C.

[0167] Table 1:

[0168] .

[0169] As shown in Table 1, the modified polylactic acid provided in Examples 1 to 4 has higher tensile strength, impact toughness, and heat deformation temperature than the comparative example, while the melting temperature and degradation time are lower than the comparative example. The modified polylactic acid provided in Examples 2 to 4 has a higher melt index than the comparative example. The modified polylactic acid provided in the examples of the present application has excellent 3D printing processability, mechanical properties, and rapid degradation, and has broad application prospects.

[0170] The above is a detailed introduction to the technical solutions provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing modified polylactic acid, characterized in that: The steps include: A first compound is provided, wherein the structural formula of the first compound is shown below: , wherein n is selected from an integer of 20 to 60; A second compound is provided, wherein the structural formula of the second compound is shown below: ; Providing polyetheramine D-400, mixing with the first compound and the second compound, and reacting to obtain modified polylactic acid.

2. The preparation method according to claim 1, characterized in that The preparation method of the first compound comprises: Providing a dihydroxy-terminated polylactic acid dispersion, wherein the dihydroxy-terminated polylactic acid dispersion comprises dihydroxy-terminated polylactic acid and a first solvent; Providing a p-carboxybenzaldehyde dispersion, wherein the p-carboxybenzaldehyde dispersion comprises p-carboxybenzaldehyde and a second solvent; The dihydroxy-terminated polylactic acid dispersion and the p-carboxybenzaldehyde dispersion are mixed and reacted to obtain a first compound.

3. The preparation method according to claim 2, characterized in that The first solvent and the second solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; and / or, In the dihydroxy-terminated polylactic acid dispersion, the molar concentration of the dihydroxy-terminated polylactic acid is 0.01 mol / L to 0.1 mol / L; and / or, The dihydroxy-terminated polylactic acid dispersion further comprises a catalyst; the catalyst comprises 4-dimethylaminopyridine; and / or, The dihydroxy-terminated polylactic acid dispersion further includes a first water absorbing agent; the first water absorbing agent includes dicyclohexylcarbodiimide; and / or, In the p-carboxybenzaldehyde dispersion, the molar concentration of p-carboxybenzaldehyde is 1 mol / L to 10 mol / L; and / or, The molar ratio of the dihydroxy-terminated polylactic acid to the p-carboxybenzaldehyde is 1:(1-5); and / or, The reaction temperature of the bishydroxyl-terminated polylactic acid and the p-carboxybenzaldehyde is 20° C. to 30° C.; the reaction time of the bishydroxyl-terminated polylactic acid and the p-carboxybenzaldehyde is 20 h to 30 h.

4. The preparation method according to claim 3, characterized in that The preparation method of the second compound comprises: An intermediate product dispersion is provided, wherein the intermediate product dispersion comprises an intermediate product and a third solvent, and the intermediate product has a structural formula as shown below: ; Providing a butanediamine dispersion, wherein the butanediamine dispersion comprises butanediamine and a fourth solvent; The intermediate product dispersion and the butanediamine dispersion are mixed and reacted to obtain a second compound.

5. The preparation method according to claim 4, characterized in that The preparation method of the intermediate product comprises: Providing an acryloyl chloride dispersion, wherein the acryloyl chloride dispersion comprises acryloyl chloride and a fifth solvent; Providing a thiocarbamate dispersion, wherein the thiocarbamate dispersion comprises thiocarbamate and a sixth solvent; The acryloyl chloride dispersion and the oxaloyl dihydrazide dispersion are mixed and reacted to obtain an intermediate product.

6. The preparation method according to claim 5, characterized in that The fifth solvent and the sixth solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; and / or, In the acryloyl chloride dispersion, the molar concentration of acryloyl chloride is 1 mol / L to 5 mol / L; and / or, The acryloyl chloride dispersion also includes an acid coating agent; the acid coating agent includes one or more of triethylamine and pyridine; and / or, In the oxalohydrazide dispersion, the molar concentration of the oxalohydrazide is 0.1 mol / L to 1 mol / L; and / or, The molar ratio of the acryloyl chloride to the oxaloylhydrazide is 1:(1-5); and / or, The reaction temperature of the acryloyl chloride and the oxaloyl hydrazide is 0° C.; the reaction time of the acryloyl chloride and the oxaloyl hydrazide is 1 h to 5 h.

7. The preparation method according to claim 4, characterized in that The third solvent and the fourth solvent are each independently selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; and / or, In the intermediate product dispersion, the molar concentration of the intermediate product is 0.1 mol / L to 1 mol / L; and / or, In the dibutylene glycol dispersion, the molar concentration of dibutylene glycol is 1 mol / L to 5 mol / L; and / or, The molar ratio of the intermediate product to the butanediamine is (1-5):1; and / or, The reaction temperature of the intermediate product and the butanediamine is 50° C. to 100° C.; the reaction time of the intermediate product and the butanediamine is 10 h to 20 h.

8. The preparation method according to claim 1, characterized in that The mixing of the polyetheramine D-400 with the first compound and the second compound comprises: providing a first compound dispersion, wherein the first compound dispersion comprises the first compound and a seventh solvent; providing a mixture dispersion, wherein the mixture dispersion comprises a mixture and an eighth solvent, wherein the mixture comprises the polyetheramine D-400 and the second compound; mixing the first compound dispersion and the mixture dispersion, reacting them, to obtain modified polylactic acid; wherein, The seventh solvent and the eighth solvent are each independently selected from one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, and acetone; and / or, In the first compound dispersion, the molar concentration of the first compound is 0.01 mol / L to 0.1 mol / L; and / or, The first compound dispersion further includes a second water absorbing agent; and / or, The second water absorbing agent includes dicyclohexylcarbodiimide; and / or, In the mixture dispersion, the molar concentration of the second compound is 0.1 mol / L to 1 mol / L; and / or, In the mixture dispersion, the molar concentration of the polyetheramine D-400 is 0.01 mol / L to 0.1 mol / L; and / or, The molar ratio of the first compound, the second compound and the polyetheramine D-400 is (1-5): (1-2): (0.1-1); and / or, The reaction temperature of the first compound, the second compound and the polyetheramine D-400 is 20° C. to 50° C.; the reaction time of the first compound, the second compound and the polyetheramine D-400 is 10 h to 20 h.

9. A modified polylactic acid, characterized in that: The modified polylactic acid is prepared by any one of the preparation methods of claims 1 to 8.

10. Use of the modified polylactic acid according to claim 9, or the modified polylactic acid prepared by the preparation method according to any one of claims 1 to 8 in 3D printing.

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