Poly(lactic acid-3-hydroxypropionic acid) copolymer and its manufacturing method

Abstract

The present invention relates to a poly(lactic acid-3-hydroxypropionic acid) copolymer containing a novel network structure and a method for producing the same.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0055420, filed April 27, 2023, and Korean Patent Application No. 10-2024-0055649, filed April 25, 2024, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a poly(lactic acid-3-hydroxypropionic acid) copolymer containing a novel network structure and a method for producing the same. [Background technology]

[0003] Poly(3-hydroxypropionic acid) has biodegradable properties, and due to its environmentally friendly properties, research using it has been actively conducted recently.

[0004] There are two main methods for producing poly(3-hydroxypropionic acid): one is a petrochemical-based method using β-propiolactone (PL) for polymerization, and the other is a bio-based method using 3-hydroxypropionic acid (3HP).

[0005] When PL is used, several synthesis steps using ethylene oxide must be performed, which is economically disadvantageous compared to the use of 3HP.

[0006] In the case of polymerization using biosynthesis of 3HP, various steps such as freeze-drying, ultra-sonication, and solvent elution must be performed to obtain poly(3-hydroxypropionic acid), which requires the use of large amounts of solvent. In the case of biosynthesis polymerized in this way, the biocontent of poly(3-hydroxypropionic acid) is 100%, but the residues remaining after fermentation contain a large amount of organic nitrogen, resulting in a high YI.

[0007] To solve this problem, attempts have been made to polycondense 3HP, but the production of high-molecular-weight poly(3-hydroxypropionic acid) is limited by the presence of cyclic oligomers as by-products. Attempts have also been made to increase the molecular weight by ROP of low-molecular-weight cyclic oligomers, but separation and purification are difficult.

[0008] Furthermore, in order for such poly(3-hydroxypropionic acid) polymers to be used in a wider variety of products, there is a demand for a technology for synthesizing them so that they have novel structures that provide excellent physical properties.

[0009] Therefore, there is a need for a method for producing poly(3-hydroxypropionic acid) from 3HP by condensation polymerization, thereby producing a polymer with a novel structure that achieves excellent physical properties and is easily applicable to a range of products. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a poly(lactic acid-3-hydroxypropionic acid) copolymer having a novel network structure.

[0011] The present invention also provides a method for producing the poly(lactic acid-3-hydroxypropionic acid) copolymer. [Means for solving the problem]

[0012] Poly(lactic acid-3-hydroxypropionic acid) copolymer In order to solve the above problems, one embodiment of the present invention provides a poly(lactic acid-3-hydroxypropionic acid) copolymer comprising: a first repeating unit derived from a poly(3-hydroxypropionic acid) polymer having a network structure; and a second repeating unit derived from lactide represented by the following chemical formula 2; wherein the first repeating unit contains a plurality of 1-1 repeating units derived from 3-hydroxypropionic acid represented by the following chemical formula 1; the network structure is formed by bonding one end group of the 1-1 repeating unit to an end group of another 1-1 repeating unit via a reactive monomer; and the alpha value measured by multi-angle light scattering (MALS) is 0.4 to 0.8. [ka]

[0013] The term "poly(lactic acid-3-hydroxypropionic acid) copolymer" used in the present invention comprises a first repeating unit derived from 3-hydroxypropionic acid and a second repeating unit derived from lactide, and includes a novel network structure in which the first repeating unit contains the 1-1 repeating unit represented by Chemical Formula 1 above.

[0014] The poly(lactic acid-3-hydroxypropionic acid) copolymer of the present invention has biodegradable properties due to the molecular structure of the repeating units. As described below, the poly(lactic acid-3-hydroxypropionic acid) copolymer of the present invention is produced by polymerizing 3-hydroxypropionic acid with a reactive monomer under specific conditions to produce a polymer with a novel network structure, which is then polymerized with lactide, thereby introducing a network structure into the final copolymer, thereby exhibiting excellent physical properties.

[0015] The term "network structure" used in the present invention may refer to a network structure that includes at least two branched structures formed by the bonding of at least three repeating units, and is distinguished from a branched structure or a hyperbranched structure with multiple branches.

[0016] The novel poly(lactic acid-3-hydroxypropionic acid) copolymer with a network structure has the appropriate molecular weight characteristics and can exhibit a high degree of crosslinking and appropriate elasticity. While polymers with a high degree of crosslinking are usually prone to breakage, the novel copolymer with a network structure according to the present invention has less brittleness due to the voids in the network structure, making it easier to apply to a variety of products.

[0017] Specifically, a poly(lactic acid-3-hydroxypropionic acid) copolymer according to one embodiment of the invention includes a plurality of 1-1 repeating units derived from 3-hydroxypropionic acid, represented by Chemical Formula 1, within a first repeating unit. The end group of any one of the 1-1 repeating units is bonded to the end group of another 1-1 repeating unit via a reactive monomer to form a new network structure, and a second repeating unit derived from lactide is copolymerized into this network structure to form the final copolymer.

[0018] The alpha value of the poly(lactic acid-3-hydroxypropionic acid) copolymer as measured by a multi-angle light scattering detector (MALS) may be 0.4 to 0.8, preferably 0.4 to 0.7. By satisfying this range, the desired network structure can be obtained.

[0019] As a result, the present invention can be manufactured into various molded products, and in particular, when manufactured into a foam form, the network structure supports the foam, allowing it to maintain its shape even after final processing.

[0020] The alpha value measured by multi-angle light scattering (MALS) is an index that can identify polymer structure. The alpha value refers to a constant value of the Mark-Houwink equation derived by MALS. An alpha value outside the above range, approaching 1, is undesirable because it indicates that the polymer structure is close to linear. Furthermore, in a crosslinked structure, an alpha value that is too low outside the above range can cause gelation, resulting in reduced processability and mechanical properties. This can make it difficult to maintain the shape of the final polymer in a foam form, making it difficult to apply to a variety of products. Specific measurement methods will be described in more detail in the experimental examples below.

[0021] A poly(lactic acid-co-3-hydroxypropionic acid) according to one embodiment of the invention comprises a first repeat unit derived from a poly(3-hydroxypropionic acid) polymer.

[0022] The first repeating unit contains a plurality of 1-1 repeating units derived from 3-hydroxypropionic acid, as represented by Chemical Formula 1, and a novel network structure is formed by bonding one end group of the 1-1 repeating units to an end group of another 1-1 repeating unit via a reactive monomer. [ka]

[0023] Here, the "end group of the 1-1 repeating unit" refers to an end group derived by the reaction of 3-hydroxypropionic acid, which is a unit monomer constituting the repeating unit, with a reactive monomer.

[0024] The reactive monomer may contain one or more reactive terminal substituents selected from the group consisting of a hydroxyl group (-OH), a carboxyl group (-COOH), an amino group (-NH), a cyano group (-CN), a thiol group (-SH), and an isocyanate group (-N=C=O). Preferably, the reactive monomer may be a polyfunctional monomer containing multiple reactive terminal substituents, which facilitates the formation of a novel network structure.

[0025] The reactive monomer is polyC 1-60 Alkylene polyol or C 1-60 alkyl dicarboxylic acids, or poly C 1-60 Alkylene polyol and C 1-60 Alkyl dicarboxylic acids can be used simultaneously.

[0026] wherein the polyC 1-60 Alkylene polyols include glycerol and 3-arm-poly(ethylene glycol). n=2~15 , 4-arm-poly(ethylene glycol) n=2~10 Examples of suitable alcohols include, but are not limited to, one or more selected from the group consisting of erythritol, pentaerythritol, di(trierythritolpropane), xylitol, sorbitol, tripentaerythritol, inositol, and β-cyclodextrin, and preferably glycerol.

[0027] Also, the above C 1-60 Examples of alkyl dicarboxylic acids include one or more selected from the group consisting of malonic acid, succinic acid, adipic acid, 1,3,5-benzenetricarboxylic acid, 1,3,5-triazine-2,4,6-tricarboxylic acid, citric acid, and 2,2-bis(hydroxymethyl)butyric acid, and preferably succinic acid, but is not limited to this. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to one embodiment of the invention includes a second repeating unit derived from lactide represented by the following chemical formula 2: [ka]

[0028] The term "lactide" refers to L-lactide, D-lactide, meso-lactide consisting of one L-form and one D-form, or a 50:50 mixture of L-lactide and D-lactide, called D,L-lactide or rac-lactide.

[0029] According to one embodiment of the invention, the poly(lactic acid-3-hydroxypropionic acid) copolymer having the novel network structure may have the following structure, but is not limited thereto. [ka]

[0030] In the above structure, R1 and R2 can represent structures derived from reactive monomers. n may be 1-100.

[0031] Preferably, the weight average molecular weight (Mw) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 100,000 to 500,000. More preferably, Mw is 120,000 or more, 150,000 or more, 170,000 or more, or 200,000 or more, and 450,000 or less, 400,000 or less, 380,000 or less, 350,000 or less, or 300,000 or less.

[0032] Preferably, the number average molecular weight (Mn) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 10,000 to 250,000. More preferably, Mn is 15,000 or more, 18,000 or more, 20,000 or more, 25,000 or more, or 30,000 or more, and 200,000 or less, 150,000 or less, 100,000 or less, 90,000 or less, 70,000 or less, 50,000 or less, or 45,000 or less.

[0033] Preferably, the poly(lactic acid-3-hydroxypropionic acid) copolymer has a polydispersity index (PDI) of 2.0 to 7.0, more preferably 2.1 or more, 2.3 or more, 2.5 or more, 2.8 or more, or 3.2 or more, and 6.8 or less, 6.3 or less, 6.0 or less, 5.5 or less, or 5.0 or less.

[0034] Preferably, the poly(lactic acid-3-hydroxypropionic acid) copolymer has a crystallization temperature (Tc) of 90 to 120°C, and more preferably 95 to 118°C. Satisfying the thermal characteristics is advantageous for achieving the intended effects. Furthermore, the poly(lactic acid-3-hydroxypropionic acid) copolymer has a crystallization temperature (Tc) of 90 to 120°C, and the sum of enthalpies (ΔH) in this range is 20 to 40 J / g, and more preferably 29 to 39 J / g. The crystallization temperature and its enthalpy can be measured by DSC (differential scanning calorimetry), and a specific measurement method therefor will be described in more detail in the experimental examples described below.

[0035] Preferably, the melting temperature (Tm) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 160 to 170°C, more preferably 165 to 168°C. Satisfying the above thermal characteristics is advantageous for achieving the intended effects. Specific measurement methods will be explained in more detail in the experimental examples below.

[0036] Method for producing poly(lactic acid-3-hydroxypropionic acid) copolymer Meanwhile, according to one embodiment of the present invention, there is provided a method for producing the aforementioned poly(lactic acid-3-hydroxypropionic acid) polymer, which can be produced from 3-hydroxypropionic acid and lactide, and the 3-hydroxypropionic acid can be produced by biosynthesis.

[0037] Therefore, preferably, the poly(lactic acid-3-hydroxypropionic acid) produced by the present invention may have a biocontent of 90% or more. The biocontent can be determined by graphitizing a sample to be measured and then analyzing the content of the radioactive isotope 14C (bio-derived) according to ASTM D6866-22.

[0038] More specifically, the method for producing poly(lactic acid-3-hydroxypropionic acid) copolymer includes a first step of polymerizing 3-hydroxypropionic acid and a reactive monomer to form an oligomer; a second step of polymerizing the oligomer to produce a poly(3-hydroxypropionic acid) polymer having a network structure; and a third step of ring-opening polymerizing the poly(3-hydroxypropionic acid) polymer and lactide to produce poly(lactic acid-3-hydroxypropionic acid) copolymer.

[0039] Here, by adjusting the preparation conditions of steps 1 and 2, a poly(3-hydroxypropionic acid) polymer having a network structure can be prepared, and the final copolymer is prepared by ring-opening polymerization of lactide. The above-mentioned descriptions regarding the 3-hydroxypropionic acid, reactive monomer, and lactide used herein are all equally applicable.

[0040] (Stage 1) Step 1 of the present invention is to melt-polymerize 3-hydroxypropionic acid and reactive monomers to produce an oligomer. The melt polymerization means that the reactants, 3-hydroxypropionic acid and reactive monomers, and the resulting oligomer are maintained in a liquid state. The reactive monomer functions to link multiple repeating units formed by 3-hydroxypropionic acid so that the polymer can form a new network.

[0041] The reactive monomer may contain one or more terminal reactive substituents selected from the group consisting of a hydroxyl group (-OH), a carboxyl group (-COOH), an amino group (-NH), a cyano group (-CN), a thiol group (-SH), and an isocyanate group (-N=C=O). Preferably, the reactive monomer may be a polyfunctional monomer containing multiple terminal reactive substituents, which facilitates the formation of a novel network structure. The specific types of the reactive monomer are the same as those described above.

[0042] Preferably, the reactive monomer is polyC 1-60 Alkylene polyol or C 1-60 The alkyl dicarboxylic acid may comprise one or more of the following: poly C 1-60 Alkylene polyol and C 1-60 The polyC may also contain an alkyl dicarboxylic acid. 1-60 Alkylene polyol and C 1-60 The specific types of alkyl dicarboxylic acids are all equally applicable to those described above.

[0043] Poly C 1-60 The alkylene polyol may be contained in an amount of 0.1 to 15 mol %, preferably 0.5 to 10 mol %, based on 100 mol of 3-hydroxypropionic acid. 1-60 The alkyl dicarboxylic acid may be contained in an amount of 0.01 to 10 mol %, preferably 0.25 to 5 mol %, relative to 100 mol of 3-hydroxypropionic acid. By using each reactive monomer in the above content range, it is easy to form a novel network structure.

[0044] In step 1, the reaction temperature is adjusted to a temperature of 80° C. to 100° C. Preferably, the reaction temperature in step 1 is 81° C. or higher, 82° C. or higher, 83° C. or higher, 84° C. or higher, or 85° C. or higher, and 99° C. or lower, 98° C. or lower, 97° C. or lower, 96° C. or lower, or 95° C. or lower.

[0045] Also, step 1 is performed at a pressure of 5 torr to 20 torr. Preferably, step 1 is performed at a pressure of 6 torr or more, 7 torr or more, 8 torr or more, or 9 torr or more, and 19 torr or less, 18 torr or less, 17 torr or less, 16 torr or less, or 15 torr or less.

[0046] The reaction time of the step 1 can be appropriately determined in consideration of the molecular weight of the oligomer produced, the yield, etc., and is preferably 1 to 3 hours.

[0047] Preferably, Step 1 is carried out in the presence of a sulfonic acid catalyst. Preferably, the sulfonic acid catalyst is p-toluenesulfonic acid, m-xylene-4-sulfonic acid, 2-mesitylenesulfonic acid, or p-xylene-2-sulfonic acid. The catalyst is used in a ratio of 0.1 to 0.5 mol % based on 3-hydroxypropionic acid.

[0048] (Stage 2) Step 2 of the present invention is a step of further polymerizing the oligomer of Step 1 to prepare a poly(3-hydroxypropionic acid) polymer having a novel network structure.

[0049] This step results in the formation of a first repeating unit derived from poly(3-hydroxypropionic acid), which contains a plurality of 1-1 repeating units derived from 3-hydroxypropionic acid represented by Chemical Formula 1. [ka]

[0050] The reactive monomer functions to link multiple 1-1 repeat units formed by 3-hydroxypropionic acid so that the polymer can form a new network.

[0051] Unlike step 1, step 2 can be carried out at a lower pressure since the reactants are oligomers.

[0052] Preferably, the reaction temperature in Step 2 is 75° C. to 95° C. More preferably, the reaction temperature in Step 2 is 80° C. or higher, or 85° C. or higher, and 94° C. or lower, 93° C. or lower, 92° C. or lower, or 91° C. or lower.

[0053] Preferably, the reaction pressure in Stage 2 is 5 torr or less. More preferably, the pressure in Stage 2 is 4 torr or less, 3 torr or less, 2 torr or less, 1 torr or less, 0.5 torr or less, 0.4 torr or less, or 0.3 torr or less, and 0.01 torr or more, 0.02 torr or more, 0.03 torr or more, 0.04 torr or more, 0.05 torr or more, 0.06 torr or more, 0.07 torr or more, 0.08 torr or more, 0.09 torr or more, or 0.1 torr or more.

[0054] The reaction time of the step 2 can be appropriately determined in consideration of the molecular weight and yield of the poly(3-hydroxypropionic acid) polymer to be produced, and is preferably 5 to 30 hours.

[0055] Preferably, the combined time of Step 1 and Step 2 is 7 to 30 hours, more preferably 7 to 24 hours.

[0056] Meanwhile, since step 2 is performed following step 1, the catalyst added in step 1 also participates in the reaction in step 2. Therefore, the catalyst described in step 1 can also be applied to step 2.

[0057] According to one embodiment of the present invention, the second step may be carried out by additionally adding a tin-based catalyst. Preferably, the tin-based catalyst is SnCl2 or Sn(oct)2. The catalyst is used in a ratio of 0.001 to 0.5 mol% based on 3-hydroxypropionic acid.

[0058] (Stage 3) Next, the third step involves ring-opening polymerization of the poly(3-hydroxypropionic acid) polymer and lactide to produce poly(lactic acid-3-hydroxypropionic acid) copolymer. By this step, the second repeating unit derived from lactide represented by the following chemical formula 2 is formed. [ka]

[0059] The lactide can be mixed in an amount of 100 to 1,000 parts by weight, preferably 300 to 1,000 parts by weight, or 500 to 900 parts by weight, per 100 parts by weight of poly(lactic acid-3-hydroxypropionic acid) copolymer. When the ring-opening reaction is carried out with the lactide mixed in this range, a novel copolymer with a network structure and excellent physical properties can be produced in the desired molecular weight range, which is preferred.

[0060] In step 3, the reaction temperature is adjusted to a temperature of 100° C. to 250° C. Preferably, the reaction temperature in step 3 is 150° C. or more, 160° C. or more, 170° C. or more, or 180° C. or more, and 240° C. or less, 230° C. or less, 220° C. or less, 210° C. or less, or 200° C. or less. Step 3 is carried out under atmospheric pressure (about 760 torr).

[0061] Furthermore, the reaction time of the step 3 can be appropriately determined in consideration of the molecular weight of the final copolymer to be produced, the yield, etc., and is preferably 1 to 3 hours.

[0062] Preferably, step 3 may be carried out by additionally adding a tin-based catalyst. Preferably, the tin-based catalyst is SnCl2 or Sn(oct)2. The catalyst is used in a ratio of 0.001 to 0.5 mol% based on lactide.

[0063] Meanwhile, if necessary, the 3-hydroxypropionic acid, reactive monomer, and lactide may be independently pretreated at 30°C to 100°C and 30 mbar to 150 mbar before steps 1, 2, and 3. The pretreatment step can remove moisture present in the 3-hydroxypropionic acid, reactive monomer, and lactide.

[0064] The novel network-structured poly(lactic acid-3-hydroxypropionic acid) polymer prepared by the above-described method has the appropriate molecular weight characteristics and can exhibit appropriate elasticity while having a high degree of crosslinking. While polymers with a high degree of crosslinking are usually prone to breakage, the novel network-structured polymer of the present invention has less breakage due to the void space within the network structure, making it easier to apply to a variety of products. [Effects of the Invention]

[0065] As described above, the present invention can effectively produce poly(lactic acid-3-hydroxypropionic acid) copolymers having a novel network structure and excellent physical properties. DETAILED DESCRIPTION OF THE INVENTION

[0066] Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited to these examples.

[0067] [Examples and Comparative Examples] Example 1 (Stage 1) Dehydrated 3-hydroxypropionic acid (70 g), 7.156 g of the reactive monomer glycerol (10 mol % relative to 3-HP), and 4.59 g of succinic acid (5 mol % relative to 3-HP) were placed in a reactor, and 295.6 mg of p-TSA (p-toluenesulfonic acid) (0.2 mol % relative to 3-HP) was added as a catalyst. The temperature and pressure in the reactor were maintained at 90°C and 10 mbar (7.5 torr), respectively, and the reaction was carried out for 2 hours to produce an oligomer.

[0068] (Stage 2) Next, the temperature and pressure in the reactor were adjusted to 80°C and 0.1 torr, respectively, and 157.4 mg of SnOct2 (0.05 mol% relative to 3-HP) was added as an additional catalyst. The reaction was continued for an additional 5 hours to produce poly(3-hydroxypropionic acid) polymer.

[0069] (Stage 3) Next, 4 g of the poly(3-hydroxypropionic acid) polymer was mixed with 40 g of lactide in a new reactor and dried at room temperature for 12 hours. 180 μL of a 0.01 M toluene solution of Sn(Oct)2 (0.03 mol% relative to lactide) was poured into the reactor, and the toluene was vacuum-dried for 30 minutes. The reactor was then filled with nitrogen and the reaction was carried out for 90 minutes in an oil bath preheated to 180°C, yielding a product containing poly(lactic acid-3-hydroxypropionic acid) copolymer with a novel network structure. To remove residual lactide from the product, devolatilization was carried out at 140°C for 4 hours to produce the final copolymer.

[0070] Examples 2 to 4 Poly(lactic acid-3-hydroxypropionic acid) copolymer was prepared in the same manner as in Example 1, except that the reaction conditions were changed as shown in Table 1 below.

[0071] Comparative Example 1 (Stage 1) 60 g of 3-hydroxypropionic acid from which moisture had been removed was placed in a reactor, and 253.4 mg of p-toluenesulfonic acid (p-TSA) (0.2 mol% relative to 3-HP) was added as a catalyst. The temperature and pressure in the reactor were maintained at 90°C and 10 mbar (7.5 torr), respectively, and the reaction was carried out for 2 hours to produce 3-hydroxypropionic acid oligomers.

[0072] (Stage 2) Next, the temperature and pressure in the reactor were adjusted to 80° C. and 0.1 torr, respectively, and the reaction was carried out for 5 hours to produce a linear poly(3-hydroxypropionic acid) polymer.

[0073] (Stage 3) Next, 4 g of the poly(3-hydroxypropionic acid) polymer was mixed with 40 g of lactide in a new reactor and dried at room temperature for 12 hours. 180 μL of a 0.01 M toluene solution of Sn(Oct)2 (0.03 mol% relative to lactide) was poured into the reactor, and the toluene was vacuum dried for 30 minutes. The reactor was then filled with nitrogen, and the reaction was carried out for 90 minutes in an oil bath preheated to 180°C, yielding a product containing poly(lactic acid-3-hydroxypropionic acid) copolymer. To remove residual lactide from the product, devolatilization was carried out at 140°C for 4 hours to produce the final copolymer.

[0074] Comparative Example 2 (Stage 1) 70 g of dried 3-hydroxypropionic acid (3HP) and 3.578 g of glycerol (5 mol % relative to 3HP) were placed in a reactor, and oligomerization reaction was carried out for 2 hours using 295.6 mg of p-TSA (0.2 mol % relative to 3HP) as a catalyst while maintaining the temperature at 90°C and 10 mbar (7.5 torr).

[0075] (Stage 2) Next, the temperature and pressure in the reactor were adjusted to 80°C and 0.1 torr, respectively, and 157.4 mg (0.05 mol% relative to 3HP) of Sn(Oct)2 was added as a cocatalyst. The reaction was continued for an additional 5 hours to produce a branched polymer.

[0076] (Stage 3) Next, 4 g of the branched polymer was mixed with 40 g of lactide in a new reactor and dried at room temperature for 12 hours. 180 μL of a 0.01 M Sn(Oct)2 solution in toluene (0.03 mol% relative to lactide) was added to the reactor, and the toluene was vacuum-dried for 30 minutes. The reactor was then filled with nitrogen and the reaction was carried out for 90 minutes in an oil bath preheated to 180°C, yielding a product containing poly(lactic acid-3-hydroxypropionic acid) copolymer with a novel network structure. To remove residual lactide from the product, devolatilization was carried out at 140°C for 4 hours to produce the final copolymer. [Table 1]

[0077] [Experimental Example] (1) Molecular weight characterization The copolymers prepared in each step in the examples and comparative examples were measured for weight average molecular weight, number average molecular weight, and polydispersity index by gel permeation chromatography (GPC, Waters Alliance e2695), and the results are shown in Table 2 below. -Solvent: chloroform (eluent) -Flow rate: 1.0ml / min -Column temperature: 40℃ -Standard: Polystyrene [Table 2]

[0078] (2) Alpha value evaluation using a multi-atomic light scattering detector (MALS) The alpha values ​​of the copolymers prepared in the examples and comparative examples were measured using a multi-atom array light scattering detector (MALS), and the results are shown in Table 3 below. First, the copolymer was dissolved in chloroform (standardized with ETOH) at a concentration of 5 mg / mL to prepare a sample. The mobile phase was prepared by filtering 1000 mL of chloroform (standardized with ETOH) using a solvent clarification system. The radius of gyration (Rg) of the polymer's solvated chain was measured using a multi-atom array (MALS) light scattering detector, and a plot of intrinsic viscosity (η) and absolute molecular weight (M) was then derived. The constant Alpha (α) was calculated using the Mark-Houwink equation (Equation 1), and the results are shown in Table 3 below.

[0079] -RI (refractive index) measurement: DAWN8 (manufacturer: Wyatt) -Viscometer (viscosity) measurement: Viscostar III (manufacturer: Wyatt) -Light scattering measurement: Optilab T-rEX (manufacturer: Wyatt) -Stationary phase: 2x Agilent PLgel MIXED-B and C, 7.5x300mm, 5μm Mobile phase: chloroform (standardized with ETOH) = 100 (v / v, %) -Flow rate: 1.0mL / min -Stationary phase temperature: 40℃ Injection volume: 100 μl (0.45 μm filtered) -Analysis time: 35 minutes - System calibration: Polystyrene (Mp: 135700) -Chloroform Refractive index:1.45

[0080] [Formula 1] log[η]=αlogM+logK In the above formula 1, [η] is the intrinsic viscosity (dl / g) of the copolymer, M is the absolute molecular weight (Absolute MW) of the copolymer, K is a constant. [Table 3]

[0081] (3) DSC (differential scanning calorimetry) thermal characterization The thermal properties (Tg, Tm, cold crystallization (result of second heating), Tc (result of first cooling), and total enthalpy (ΔH)) of the copolymers prepared in the examples and comparative examples were measured using a TA DSC250 model device under nitrogen gas flow conditions, and the results are shown in Table 4 below. Heat from 40℃ to 190℃ at 5℃ / min (1st heating) / Maintain temperature at 190℃ for 10 minutes Cooling from 190℃ to -60℃ at 5℃ / min (1st cooling) / Maintain temperature at -60℃ for 10 minutes -60℃~190℃ at 5℃ / min (2nd heating) [Table 4]

[0082] Generally, the faster the crystallization rate, the larger the enthalpy of Tc, and the less or no cold crystallization there is. The higher the crystallinity, the larger the enthalpy of Tm. Furthermore, while a high degree of crystallinity increases the strength of a material, it also tends to be brittle and lacks elasticity. However, in the case of a novel network structure such as that of the present invention, it has been confirmed that the brittleness can be reduced by lowering the degree of crystallinity. In Comparative Example 2, the enthalpy of Tc was significantly lower than in the Examples, confirming the occurrence of cold crystallization. This confirmed that the rate of crystallization was slower than in the Examples. Furthermore, the enthalpy value of Tm confirmed that the degree of crystallization was lower than in the Examples.

Claims

1. The polymer comprises a first repeating unit derived from a poly(3-hydroxypropionic acid) polymer having a network structure; and a second repeating unit derived from lactide represented by the following chemical formula 2: The first repeating unit includes a plurality of 1-1 repeating units derived from 3-hydroxypropionic acid represented by the following Chemical Formula 1: The network structure is formed by bonding one end group of the 1-1 repeating unit to an end group of another 1-1 repeating unit via a reactive monomer; The alpha value measured by a multi-angle light scattering detector (MALS) is 0.4 to 0.

8. Poly(lactic acid-3-hydroxypropionic acid) copolymer. 【Chemistry 1】

2. The network structure includes at least two branched structures formed by bonding at least three 1-1 repeating units together. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

3. The reactive monomer may include a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NH ２ ), containing one or more terminal reactive substituents selected from the group consisting of a cyano group (—CN), a thiol group (—SH), and an isocyanate group (—N═C═O); The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

4. The reactive monomer is polyC １－６０ Alkylene polyol or C １－６０ alkyl dicarboxylic acids, The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

5. The polyC １－６０ Alkylene polyols include glycerol, 3-arm-poly(ethylene glycol), ｎ＝２～１５ , 4-arm-poly(ethylene glycol) ｎ＝２～１０ erythritol, pentaerythritol, di(trierythritol propane), xylitol, sorbitol, tripentaerythritol, inositol, and β-cyclodextrin; The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 4.

6. Said C １－６０ The alkyl dicarboxylic acid is at least one selected from the group consisting of malonic acid, succinic acid, adipic acid, 1,3,5-benzenetricarboxylic acid, 1,3,5-triazine-2,4,6-tricarboxylic acid, citric acid, and 2,2-bis(hydroxymethyl)butyric acid. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 4.

7. The weight average molecular weight (Mw) of the copolymer is 100,000 to 500,000. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

8. The number average molecular weight (Mn) of the copolymer is 10,000 to 250,000. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

9. The polydispersity index (PDI) of the copolymer is 2.0 to 7.0; The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

10. The copolymer has a crystallization temperature (Tc) of 90 to 120°C, and a sum of enthalpies (ΔH) in this region is 20 to 40 J / g. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

11. The melting temperature (Tm) of the copolymer is 160 to 170°C. The poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

12. A first step of polymerizing 3-hydroxypropionic acid and reactive monomers to form oligomers; a second step of polymerizing the oligomer to produce a poly(3-hydroxypropionic acid) polymer having a network structure; and a third step of ring-opening polymerizing the poly(3-hydroxypropionic acid) polymer and lactide to produce a poly(lactic acid-3-hydroxypropionic acid) copolymer; A method for producing the poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1.

13. The reactive monomer may include a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NH ２ ), containing one or more terminal reactive substituents selected from the group consisting of a cyano group (—CN), a thiol group (—SH), and an isocyanate group (—N═C═O); The method for producing the poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 12.

14. The reactive monomer is polyC １－６０ Alkylene polyol or C １－６０ alkyl dicarboxylic acids, The method for producing the poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 12.

15. The polyC １－６０ The alkylene polyol is contained in an amount of 0.1 to 15 mol % based on 100 mol of 3-hydroxypropionic acid, Said C １－６０ The alkyl dicarboxylic acid is contained in an amount of 0.01 to 5 mol% based on 100 mol of 3-hydroxypropionic acid. The method for producing the poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 14.

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