Modified polylactic acid as well as preparation method and application thereof

Abstract

The invention discloses modified polylactic acid as well as a preparation method and application thereof, and relates to the technical field of high polymer materials. The structural formula of the modified polylactic acid is as follows: # imgabs0 #; wherein m is an integer selected from 2-10; and n is an integer selected from 30-100. The modified polylactic acid provided by the embodiment of the invention has excellent 3D printing processing performance, mechanical performance and rapid degradation capability, and has a wide application prospect.

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 low processing difficulty, environmental friendliness and biocompatibility. PLA has relatively excellent mechanical strength (greater than 40MPa) and good dimensional stability, and these properties mainly rely on its high molecular weight (60,000 to 100,000). However, high molecular weight PLA has the problem of slow degradation rate, and its degradation requires harsh conditions, such as composting conditions and temperatures above 60 ° C, in order to degrade 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 its synthesis is less difficult and low cost, making it more promising in some applications.

[0004] However, low molecular weight PLA has poor mechanical properties and is usually difficult to shape, 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 embodiment of the present application is implemented as follows. In the first aspect, the embodiment of the present application provides a modified polylactic acid, and the structural formula of the modified polylactic acid is shown as follows: ; Wherein, m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0007] In a second aspect, the present invention also provides a method for preparing a modified polylactic acid, comprising the following steps: A first compound is provided, wherein the structural formula of the first compound is shown as follows: , 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 as follows: ; Providing polyetheramine D-400, mixing with the first compound and the second compound, and reacting to obtain modified polylactic acid.

[0008] Optionally, in some embodiments of the present application, the method for preparing 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.

[0009] 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, 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 also includes a catalyst; the catalyst includes 4-dimethylaminopyridine; and / or, The dihydroxy-terminated polylactic acid dispersion also 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 dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde is 20° C. to 30° C.; the reaction time of the dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde is 20 h to 30 h.

[0010] Optionally, in some embodiments of the present application, the method for preparing the second compound comprises:

[0011] 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 as follows: ; 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.

[0012] Optionally, in some embodiments of the present application, the method for preparing the intermediate product comprises: Providing an acryloyl chloride dispersion, wherein the acryloyl chloride dispersion comprises acryloyl chloride and a fifth solvent; Providing a thiocarbamide dispersion, wherein the thiocarbamide dispersion comprises thiocarbamide and a sixth solvent; The acryloyl chloride dispersion and the oxaloyl hydrazide dispersion are mixed and reacted to obtain an intermediate product.

[0013] 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, 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 oxalohydrazide is 0.1 mol / L to 1 mol / L; and / or, The molar ratio of the acryloyl chloride to the oxaloyl hydrazide 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.

[0014] 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, 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 diamine is (1-5):1; and / or, The reaction temperature of the intermediate product and the diamine is 50° C. to 100° C.; the reaction time of the intermediate product and the diamine is 10 h to 20 h.

[0015] 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, 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 also includes a second water absorbing agent; and / or, The second water absorbing agent comprises 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; and / or, The structural formula of the modified polylactic acid is shown below: ; Wherein, m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0016] In a third aspect, the embodiments of the present application also 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.

[0017] 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

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 paying any creative work.

[0019] 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

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0021] In this application, unless otherwise stated, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels and do not impose numerical requirements or establish an order.

[0022] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. 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.

[0023] In this application, "at least one" means one or more, and "plurality" means two or more. "One or several", "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 be single or multiple.

[0024] 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 rigid 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 numerical values ​​within the range. For example, the range description 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 apply 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.

[0025] The structural formula and molecular weight of some chemical reagents used in this application are described as follows: Dihydroxy terminated polylactic acid (dihydroxy PLA): , n is an integer of 30 to 100, number average molecular weight = 5000, purchased from Hubei Yamed Biopharmaceutical Co., Ltd.; p-Carboxybenzaldehyde: , molecular weight = 150.13; p-Carboxybenzaldehyde: , molecular weight = 122.17; Dicyclohexylcarbodiimide: , molecular weight = 206.33; Acryloyl chloride: , molecular weight = 90.5; Oxalyl hydrazide: , molecular weight = 118.09; Butanediamine: , molecular weight = 88.15; Polyetheramine D-400: , where m is an integer from 2 to 10, and the number average molecular weight = 400; Triethylamine: Molecular weight = 101.19.

[0026] The technical solution of this application is as follows: 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 as follows: ; Wherein, m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0027] It is understood that m and n represent the degree of polymerization respectively.

[0028] 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.

[0029] Second, see Figure 1 The present invention provides a method for preparing a modified polylactic acid, comprising the following steps: Step S11, providing a first compound, the structural formula of the first compound is shown as follows: , wherein n is selected from an integer of 20 to 60; Step S12: providing a second compound, wherein the structural formula of the second compound is as shown below: ; Step S13, providing polyetheramine D-400, mixing it with the first compound and the second compound, and reacting them to obtain modified polylactic acid.

[0030] The preparation method of modified polylactic acid provided in the present application adopts low molecular weight polylactic acid as a basic raw material, uses dynamic imine bonds as connection points for chain extension, and introduces quadruple hydrogen bonds between molecules to obtain supramolecular effects, which serve as dynamic sacrificial bonds to give polylactic acid excellent mechanical toughness. At the same time, a small amount of long-chain polyetheramine is used for chain extension to regulate the crystallinity and melt fluidity of polylactic acid, thereby further improving the impact resistance and 3D printing performance of polylactic acid materials. 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, thereby ensuring that it can be rapidly biodegraded.

[0031] In the step S11: In some embodiments, the method for preparing the first compound comprises: 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; Step S112, providing a p-carboxybenzaldehyde dispersion, wherein the p-carboxybenzaldehyde dispersion comprises p-carboxybenzaldehyde and a second solvent; Step S113, mixing the dihydroxy-terminated polylactic acid dispersion and the p-carboxybenzaldehyde dispersion, reacting to obtain a first compound.

[0032] 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.

[0033] In some embodiments, 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, 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 above values, etc. Within the molar concentration range, the dihydroxy-terminated polylactic acid is conducive to uniform dissolution and dispersion.

[0034] In some embodiments, the dihydroxy-terminated polylactic acid dispersion further includes a catalyst.

[0035] Further, the catalyst includes 4-dimethylaminopyridine (DMAP).

[0036] In some embodiments, the dihydroxy-terminated polylactic acid dispersion further includes a first water absorbing agent.

[0037] Furthermore, the first water absorbing agent includes dicyclohexylcarbodiimide (DCC).

[0038] In some embodiments, in the p-carboxybenzaldehyde dispersion, the molar concentration of the p-carboxybenzaldehyde is 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, etc. Within the molar concentration range, the p-carboxybenzaldehyde is facilitated to be uniformly dissolved and dispersed.

[0039] In some embodiments, the molar ratio of the dihydroxy-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 above ratios. Within the molar ratio range, the dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde are conducive to the efficient reaction to generate the first compound, thereby improving the yield of the first compound.

[0040] In some embodiments, the reaction temperature of the dihydroxy-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 above values, etc.; the reaction time of the dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde is 20h to 30h, for example, 20h, 24h, 26h, 28h, 30h, or a range between any two of the above values, etc. In this way, under the reaction conditions, it is conducive to the efficient generation of the first compound.

[0041] In some embodiments, the synthesis route of the reaction of the dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde to generate the first compound is shown in the following formula: .

[0042] In the step S12: In some embodiments, the method for preparing the second compound comprises: Step S121, providing an intermediate product dispersion liquid, wherein the intermediate product dispersion liquid includes an intermediate product and a third solvent, and the structural formula of the intermediate product is as follows: ; Step S122, providing a dibutylene diamine dispersion, wherein the dibutylene diamine dispersion comprises dibutylene diamine and a fourth solvent; Step S123, mixing the intermediate product dispersion and the dibutylene diamine dispersion, and reacting them to obtain a second compound.

[0043] In some embodiments, the method for preparing the intermediate product comprises: Step S1211, providing an acryloyl chloride dispersion, wherein the acryloyl chloride dispersion includes acryloyl chloride and a fifth solvent; Step S1212, providing an oxalohydrazide dispersion, wherein the oxalohydrazide dispersion comprises oxalohydrazide and a sixth solvent; Step S1213, mixing the acryloyl chloride dispersion and the oxaloyl hydrazide dispersion, reacting to obtain an intermediate product.

[0044] 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.

[0045] In some embodiments, in the acryloyl chloride dispersion, the molar concentration of the acryloyl chloride 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 above values, etc. Within the molar concentration range, the acryloyl chloride is facilitated to be uniformly dissolved and dispersed.

[0046] In some embodiments, the acryloyl chloride dispersion also includes an acidifying agent.

[0047] Furthermore, the acid coating agent includes one or more of triethylamine and pyridine.

[0048] In some embodiments, in the oxalohydrazide dispersion, the molar concentration of the oxalohydrazide 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, etc. Within the molar concentration range, the uniform dissolution and dispersion of the oxalohydrazide is facilitated.

[0049] In some embodiments, the molar ratio of the acryloyl chloride to the 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, etc. Within the molar ratio range, it is beneficial for the acryloyl chloride and the oxaloyl hydrazide to react efficiently to generate an intermediate product, thereby improving the yield of the intermediate product.

[0050] 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 1h to 5h, for example, 1h, 2h, 3h, 4h, 5h or a range between any two of the above values. In this way, under the reaction conditions, it is conducive to efficiently generate the intermediate product.

[0051] It should be noted that the reaction between the acryloyl chloride and the oxaloylhydrazide can be carried out in an ice bath.

[0052] In some embodiments, the synthesis route of the reaction of the acryloyl chloride and the oxaloyl hydrazide to generate an intermediate product is shown in the following formula: .

[0053] 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.

[0054] In some embodiments, in the intermediate product dispersion, the molar concentration of the intermediate product 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, etc. Within the molar concentration range, the intermediate product is conducive to uniform dissolution and dispersion.

[0055] In some embodiments, in the dibutylene glycol dispersion, the molar concentration of dibutylene glycol 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 above values, etc. Within the molar concentration range, the dibutylene glycol is conducive to uniform dissolution and dispersion.

[0056] In some embodiments, the molar ratio of the intermediate product to the diamine 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 the molar ratio range, the intermediate product and the diamine are conducive to the efficient reaction to generate the second compound, thereby increasing the yield of the second compound.

[0057] In some embodiments, the reaction temperature of the intermediate product and the diamine 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 above values, etc.; the reaction time of the intermediate product and the diamine is 10h to 20h, for example, 10h, 12h, 14h, 16h, 18h, 20h, or a range between any two of the above values, etc. Thus, under the reaction conditions, it is conducive to the efficient generation of the second compound.

[0058] In some embodiments, the synthesis route of the reaction between the intermediate product and the diamine to generate the second compound is as shown below: .

[0059] In step S13: In some embodiments, the mixture of the polyetheramine D-400, the first compound and the second compound comprises: Step S131, providing a first compound dispersion, wherein the first compound dispersion includes the first compound and a seventh solvent; 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; Step S133: mixing the first compound dispersion and the mixture dispersion to react and obtain modified polylactic acid.

[0060] 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.

[0061] In some embodiments, in the first compound dispersion, the molar concentration of the first compound 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 above values, etc. Within the molar concentration range, the first compound is facilitated to be uniformly dissolved and dispersed.

[0062] In some embodiments, the first compound dispersion further includes a second water absorbing agent.

[0063] Furthermore, the second water absorbing agent includes dicyclohexylcarbodiimide (DCC).

[0064] In some embodiments, in the mixture dispersion, the molar concentration of the second compound 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, etc. Within the molar concentration range, the mixture is facilitated to be uniformly dissolved and dispersed.

[0065] In some embodiments, in the mixture dispersion, the molar concentration of the polyetheramine D-400 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 above values, etc. Within the molar concentration range, the mixture is facilitated to be uniformly dissolved and dispersed.

[0066] 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 the molar ratio range, the first compound, the second compound and the polyetheramine D-400 are conducive to the efficient reaction to generate modified polylactic acid, thereby improving the yield of modified polylactic acid.

[0067] 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, 50°C; the reaction time of the first compound, the second compound and the polyetheramine D-400 is 10h to 20h, for example, 10h, 12h, 14h, 16h, 18h, 20h or a range between any two of the above values. In this way, under the reaction conditions, it is conducive to the efficient generation of the modified polylactic acid.

[0068] In some embodiments, the structural formula of the modified polylactic acid is as shown below: ; Wherein, m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

[0069] It is understood that m and n represent the degree of polymerization respectively.

[0070] In a third aspect, the embodiments of the present application also provide applications of the modified polylactic acid or the modified polylactic acid prepared by the above-mentioned preparation method.

[0071] Specifically, the modified polylactic acid has excellent 3D printing processing performance, mechanical properties and rapid degradation ability, and can be applied to 3D printing.

[0072] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.

[0073] Embodiment 1: This embodiment provides a modified polylactic acid, and the preparation method thereof comprises the following steps: 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 for 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 a three-necked flask at 25°C, keep stirring and circulating nitrogen for protection, and react at 25°C for 24 hours. After the reaction is completed, remove the by-products generated by the water absorption of dicyclohexylcarbodiimide by suction filtration, and remove the tetrahydrofuran in the system by rotary evaporation of the filtrate at 35°C. Then, rinse the precipitate after rotary evaporation with excess ethanol to remove the remaining p-carboxybenzaldehyde and 4-dimethylaminopyridine to obtain the first compound; 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 pass 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; Step 3: Add 0.18 mol of diamine and 100 mL of anhydrous dioxane to a 250 mL three-necked flask, start stirring, heat to 80°C, then take 0.03 mol of the intermediate product and dissolve it in 50 mL of anhydrous dioxane, and gradually drip it into the three-necked flask at 80°C through a constant pressure funnel, and pass nitrogen gas for protection. After the addition is completed, react at 80°C for 12 hours. After the reaction is completed, perform rotary evaporation at 70°C to remove the residual dioxane in the system, and rinse with deionized water at room temperature to remove the unreacted diamine to obtain the second compound; Step 4: Take 0.02mol of the first compound, 0.04mol of dicyclohexylcarbodiimide and 300mL of anhydrous DMF and add them to a 500mL three-necked flask, start stirring, introduce circulating nitrogen protection, heat to 30°C, and keep stirring until the reactants are completely dissolved. Take 0.019mol of the second compound and 0.001mol of polyetheramine D-400 and dissolve them in 50ml of anhydrous DMF, pour them into a three-necked flask, stir evenly, keep circulating nitrogen protection, and react at 30°C for 12h, during which the by-products generated by the water absorption of dicyclohexylcarbodiimide are precipitated. After the reaction is completed, the by-products generated by the water absorption of dicyclohexylcarbodiimide are removed by suction filtration, the filtrate is poured into excess methanol for precipitation, suction filtration is performed again, and the precipitate is dried at 60°C in a blast drying oven to obtain modified polylactic acid.

[0074] Embodiment 2: 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.

[0075] Embodiment 3: 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.

[0076] Embodiment 4: 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.

[0077] Comparative Example: 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.).

[0078] The modified polylactic acid of Examples 1 to 4 and the modified polylactic acid of the comparative example were used to prepare tensile splines by fused deposition modeling (FDM) in 3D printing. Specifically, the tensile spline size was set according to GB / T1040.3-2006 standard, a standard spline model of polylactic acid was made by using SolidWorks 3D modeling software, and a CR-5 (model) desktop 3D printer (Shenzhen Innovation 3D Technology Co., Ltd.) was used for printing and molding, with a printing speed of 30 mm / s, a printing temperature of 180°C / 200°C (the printing temperature of Examples 1 to 4 was 180°C, and the printing temperature of the comparative example was 200°C), a layer height of 0.2 mm, and the prepared tensile spline size was 150 mm*10 mm*4 mm.

[0079] 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.

[0080] 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.

[0081] The melt index determination is carried out in accordance with the standard GB / T 3682.1-2018 "Plastics Thermoplastics Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) Determination Part 1: Standard Method", the test temperature is 190°C, and the weight used is 2.1kg.

[0082] Impact toughness is 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 in accordance with standard GB / T 29284-2024.

[0083] The melting temperature was determined in accordance with GB / T 19466.3-2004.

[0084] Before composting, polylactic acid was first hydrolyzed under acidic conditions to generate low molecular weight polylactic acid fragments before the degradation performance was measured. Specifically, the polylactic acid sample was placed in a hydrochloric acid aqueous solution (PH < 3), mechanically stirred at room temperature for 1 hour, filtered, and the precipitate was washed with deionized water. The composting degradation experiment temperature was maintained at 56~60℃; Table 1 .

[0085] As shown in Table 1, the tensile strength, impact toughness, and heat deformation temperature of the modified polylactic acid provided in Examples 1 to 4 are higher than those of the comparative example, and the melting temperature and degradation time are lower than those of the comparative example. The melt index of the modified polylactic acid in Examples 2 to 4 is higher than that of 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 capability, and has broad application prospects.

[0086] The technical solutions provided by the embodiments of the present application are introduced in detail above. 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 technical personnel in this field, according to the idea of ​​the present application, there will 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 modified polylactic acid, characterized in that: The structural formula of the modified polylactic acid is shown below: ； Wherein, m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

2. 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 as follows: , 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 as follows: ; Providing polyetheramine D-400, mixing with the first compound and the second compound, and reacting to obtain modified polylactic acid.

3. The preparation method according to claim 2, 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.

4. The preparation method according to claim 3, 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 also includes a catalyst; the catalyst includes 4-dimethylaminopyridine; and / or, The dihydroxy-terminated polylactic acid dispersion also 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 dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde is 20° C. to 30° C.; the reaction time of the dihydroxy-terminated polylactic acid and the p-carboxybenzaldehyde is 20 h to 30 h.

5. The preparation method according to claim 2, 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 structural formula of the intermediate product is shown as follows: ; 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.

6. The preparation method according to claim 5, 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 thiocarbamide dispersion, wherein the thiocarbamide dispersion comprises thiocarbamide and a sixth solvent; The acryloyl chloride dispersion and the oxaloyl hydrazide dispersion are mixed and reacted to obtain an intermediate product.

7. The preparation method according to claim 6, 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 oxalohydrazide is 0.1 mol / L to 1 mol / L; and / or, The molar ratio of the acryloyl chloride to the oxaloyl hydrazide 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.

8. The preparation method according to claim 5, 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 diamine is (1-5):1; and / or, The reaction temperature of the intermediate product and the diamine is 50° C. to 100° C.; the reaction time of the intermediate product and the diamine is 10 h to 20 h.

9. The preparation method according to claim 2, 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, and obtaining 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 also includes a second water absorbing agent; and / or, The second water absorbing agent comprises 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; and / or, The structural formula of the modified polylactic acid is shown below: ; wherein m is selected from an integer of 2 to 10; and n is selected from an integer of 30 to 100.

10. Use of the modified polylactic acid according to claim 1 or the modified polylactic acid prepared by the preparation method according to any one of claims 2 to 9 in 3D printing.

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