A poly(lactic acid-3-hydroxypropionic acid) copolymer and a method for preparing the same.

Abstract

Invention details;

Description

Poly(lactic-3-hydroxypropionic acid) copolymer and method for producing the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0055420, filed April 27, 2023, and Korean Patent Application No. 10-2024-0055649, filed April 25, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a poly(lactic acid-3-hydroxypropionic acid) copolymer comprising a novel network structure and a method for producing the same.

[0004]

[0005] Poly(3-hydroxypropionic acid) has biodegradable properties, and due to these environmentally friendly properties, research on its use has been actively conducted recently.

[0006]

[0007] 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-hydroxypropinic acid (3HP).

[0008]

[0009] When using PL, multiple synthesis steps using ethylene oxide are required, so there is a disadvantage in terms of economic feasibility compared to when using 3HP.

[0010]

[0011] Polymerization using 3HP biosynthesis requires multiple steps, including freeze-drying, ultrasonication, and solvent extraction, to obtain poly(3-hydroxypropionic acid), necessitating the use of large quantities of solvent. While the bio-based polymerization yields 100% bio-based poly(3-hydroxypropionic acid), the residual residues after fermentation often result in a high organic nitrogen content and a high YI.

[0012]

[0013] To address this issue, attempts have been made to polycondense 3HP, but the formation of byproducts in the form of cyclic oligomers limits the ability to obtain high-molecular-weight poly(3-hydroxypropionic acid). Attempts have been made to increase molecular weight by ROP of low-molecular-weight cyclic oligomers, but separation and purification are difficult.

[0014]

[0015] In addition, there is a need for a technology to synthesize these poly(3-hydroxypropionic acid) polymers with a novel structure that exhibits excellent physical properties so that they can be applied to a wider range of product groups.

[0016]

[0017] Therefore, there is a need for a method of producing poly(3-hydroxypropionic acid) by polycondensation from 3HP, which has excellent physical properties and a novel structure that is easy to apply to a product group.

[0018]

[0019] The present invention provides a poly(lactic acid-3-hydroxypropionic acid) copolymer having a novel network structure.

[0020] In addition, the present invention provides a method for producing the poly(lactic acid-3-hydroxypropionic acid) copolymer.

[0021]

[0022] poly(lactic-3-hydroxypropionic acid) copolymer

[0023] In order to solve the above problem, according to one embodiment of the present invention, a poly(lactic acid-3-hydroxypropionic acid) copolymer is provided, which 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; and which comprises a plurality of 3-hydroxypropionic acid-derived 1-1 repeating units represented by the following chemical formula 1 within the first repeating unit, wherein the network structure is formed by bonding a terminal group of any one of the 1-1 repeating units to a terminal group of another 1-1 repeating unit by a reactive monomer, and has an alpha value of 0.4 to 0.8 according to a multi-angle light scattering detector (MALS).

[0024] [Chemical Formula 1]

[0025]

[0026] [Chemical Formula 2]

[0027] .

[0028]

[0029] The term 'poly(lactic acid-3-hydroxypropionic acid) copolymer' used in the present invention includes a first repeating unit derived from 3-hydroxypropionic acid and a second repeating unit derived from lactide, and includes a novel network structure including a first-1 repeating unit represented by the chemical formula 1 within the first repeating unit.

[0030]

[0031] According to the present invention, the poly(lactic acid-3-hydroxypropionic acid) copolymer has biodegradable properties due to the molecular structure of the repeating unit. As described below, the poly(lactic acid-3-hydroxypropionic acid) copolymer according to the present invention is prepared by polymerizing 3-hydroxypropionic acid with a reactive monomer under specific conditions to produce a polymer having a novel network structure, and then polymerizing this with lactide, thereby introducing a network structure into the final copolymer, thereby exhibiting excellent physical properties.

[0032]

[0033] The term “network structure” used in the present invention may mean a network structure including at least two branch structures formed by combining at least three or more repeating units, and this is distinguished from a branched structure or a hyperbranched structure of multiple branches.

[0034] The novel network structured poly(lactic acid-3-hydroxypropionic acid) copolymer can exhibit appropriate molecular weight characteristics, a high degree of crosslinking, and appropriate elasticity at the same time. Typically, polymers with a high degree of crosslinking exhibit brittle characteristics, but the novel network structured copolymer according to the present invention has elasticity supplemented by empty spaces within the network structure, thereby reducing brittle characteristics (brittleness), and thus is easily applicable to various product groups.

[0035] Specifically, a poly(lactic acid-3-hydroxypropionic acid) copolymer according to one embodiment of the invention includes a plurality of 3-hydroxypropionic acid-derived 1-1 repeating units represented by Chemical Formula 1 within a first repeating unit. A terminal group of any one of the 1-1 repeating units bonds with a terminal group of another 1-1 repeating unit via a reactive monomer, thereby forming a novel network structure, and a lactide-derived second repeating unit is copolymerized with the network structure to form a final copolymer.

[0036]

[0037] The alpha value of the poly(lactic acid-3-hydroxypropionic acid) copolymer according to a multi-angle light scattering detector (MALS) may be 0.4 to 0.8, and preferably 0.4 to 0.7. By satisfying the above range, the desired network structure can be achieved.

[0038] Accordingly, the present invention can be manufactured into various molded products, and in particular, when manufactured into a foam shape, the mesh structure supports the foam so that the shape is maintained without collapsing even after final processing.

[0039] The alpha value obtained by a multi-angle light scattering detector (MALS) is an indicator that can be used to determine the structure of a polymer, and the alpha value refers to the constant value of the Mark-Houwink equation derived from the multi-angle light scattering detector (MALS). If the alpha value is outside the above range and approaches 1, it means that the structure of the polymer is approaching linearity, so it is not suitable. In addition, if the alpha value in the cross-linked structure is too low and outside the above range, gelation occurs, which reduces processability and mechanical properties, and accordingly, it is difficult to maintain the shape of the final polymer in a foam form, making it difficult to apply to various product groups. The specific measurement method will be described in more detail in the experimental examples described below.

[0040]

[0041] A poly(lactic acid-3-hydroxypropionic acid) copolymer according to one embodiment of the invention comprises a first repeating unit derived from a poly(3-hydroxypropionic acid) polymer.

[0042] A plurality of 3-hydroxypropionic acid-derived 1-1 repeating units represented by Chemical Formula 1 are included within the above 1-1 repeating unit, and a terminal group of any one of the 1-1 repeating units is bonded to a terminal group of another 1-1 repeating unit by a reactive monomer, thereby forming a new network structure.

[0043] [Chemical Formula 1]

[0044]

[0045] Here, the “terminal group of the 1-1 repeating unit” means a terminal group derived by the reaction of 3-hydroxypropionic acid, a monomer forming the repeating unit, with a reactive monomer.

[0046]

[0047] The above reactive monomer may include at least one terminal reactive substituent selected from the group consisting of a hydroxyl group (-OH), a carboxyl group (-COOH), an amino group (-NH2), a cyano group (-CN), a thiol group (-SH), and an isocyanate group (-N=C=O). Preferably, it may be a multifunctional monomer including multiple terminal reactive substituents, thereby facilitating the formation of a novel network structure.

[0048] The above reactive monomer is polyC 1-60 Alkylene polyol or C 1-60 It may be one or more selected from alkyl dicarboxylic acids, and poly C 1-60 Alkylene polyols and C 1-60 Alkyl dicarboxylic acids may be used simultaneously.

[0049] Here, the polyC 1-60 Alkylene polyols include glycerol, 3-arm-poly(ethylene glycol) n=2~15, 4-arm-poly(ethylene glycol) n=2~10 , at least one selected from the group consisting of erythritol, pentaerythritol, di(trierythritolpropane), xylitol, sorbitol, tripentaerythritol, inositol and ß-cyclodextrin, preferably glycerol, but not limited thereto.

[0050] Also, the above C 1-60 The alkyl dicarboxylic acid may include 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, and preferably succinic acid, but is not limited thereto.

[0051]

[0052] A poly(lactic acid-3-hydroxypropionic acid) copolymer according to one embodiment of the invention comprises a second repeating unit derived from lactide represented by the following chemical formula 2.

[0053] [Chemical Formula 2]

[0054] .

[0055] The above 'lactide' refers to L-lactide, D-lactide, meso-lactide consisting of one L-form and one D-form, or D,L-lactide or rac-lactide, which is a mixture of L-lactide and D-lactide in a 50:50 weight ratio.

[0056]

[0057] 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.

[0058]

[0059] In the above structure, R1 and R2 may mean a structure derived from a reactive monomer.

[0060] n can be from 1 to 100.

[0061]

[0062] Preferably, the weight average molecular weight (Mw) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 100,000 to 500,000. More preferably, it 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.

[0063]

[0064] Preferably, the number average molecular weight (Mn) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 10,000 to 250,000. More preferably, it 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.

[0065]

[0066] Preferably, the polydispersity index (PDI) of the poly(lactic-3-hydroxypropionic acid) copolymer is 2.0 to 7.0. More preferably, it is 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.

[0067]

[0068] Preferably, the crystallization temperature (Tc) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 90 to 120°C, and preferably, 95°C to 118°C. By satisfying the above thermal characteristics, it is advantageous to achieve the desired effect. In addition, the crystallization temperature (Tc) of the poly(lactic acid-3-hydroxypropionic acid) copolymer is 90 to 120°C, and the total enthalpy (ΔH) in the corresponding region 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 thereof will be described in more detail in the experimental examples described below.

[0069]

[0070] 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 in achieving the desired effect. The specific measurement method thereof will be described in more detail in the experimental examples described below.

[0071]

[0072] Method for producing poly(lactic-3-hydroxypropionic acid) polymer

[0073] Meanwhile, according to one embodiment of the present invention, a method for producing the above-described poly(lactic acid-3-hydroxypropionic acid) polymer is provided, which can be produced from 3-hydroxypropionic acid and lactide, and 3-hydroxypropionic acid can be produced through biosynthesis.

[0074] Therefore, preferably, the poly(lactic-3-hydroxypropionic acid) manufactured according to the present invention may have a bio-content of 90% or more. The bio-content can be determined by analyzing the content of the radioactive isotope 14C (bio-derived) after graphitizing the sample to be measured using the ASTM D6866-22 method.

[0075]

[0076] More specifically, the method for producing a poly(lactic acid-3-hydroxypropionic acid) polymer comprises 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 a poly(lactic acid-3-hydroxypropionic acid) copolymer.

[0077] At this time, by controlling the manufacturing conditions of steps 1 and 2, a poly(3-hydroxypropionate) polymer having a network structure can be manufactured, and the final copolymer is manufactured by ring-opening polymerization of lactide. Here, the description of 3-hydroxypropionic acid, reactive monomer, and lactide used can all be applied equally to the above.

[0078]

[0079] (Step 1)

[0080] The above step 1 of the present invention is a step of producing an oligomer by melt polymerizing 3-hydroxypropionic acid and a reactive polymer. The above melt polymerization means that the reactants, 3-hydroxypropionic acid and the reactive polymer, and the product, the oligomer, remain in a liquid state.

[0081]

[0082] The above reactive monomer functions to link multiple repeating units formed by 3-hydroxypropionic acid so that the polymer can form a new network.

[0083] The reactive monomer may include at least one terminal reactive substituent selected from the group consisting of a hydroxyl group (-OH), a carboxyl group (-COOH), an amino group (-NH2), a cyano group (-CN), a thiol group (-SH), and an isocyanate group (-N=C=O). Preferably, the reactive monomer may be a multifunctional monomer including multiple terminal reactive substituents, thereby facilitating the formation of a novel network structure. The specific types of the reactive monomer may all be equally applied to the above-mentioned contents.

[0084] Preferably, the reactive monomer is polyC 1-60 Alkylene polyol or C 1-60 It may contain at least one type of alkyl dicarboxylic acid, preferably poly C. 1-60 Alkylene polyols and C 1-60 It may simultaneously contain alkyl dicarboxylic acid. The poly C 1-60 Alkylene polyols and C 1-60 The specific types of alkyl dicarboxylic acids can all be applied equally to the above-mentioned contents.

[0085] The above poly C 1-60 The alkylene polyol may be included in an amount of 0.1 to 15 mol%, preferably 0.5 to 10 mol%, based on 100 mol of 3-hydroxypropionic acid. In addition, the C 1-60 The alkyl dicarboxylic acid, 3-hydroxypropionic acid, may be included in an amount of 0.01 to 10 mol%, preferably 0.25 to 5 mol%, based on 100 mol of the monomer. By using each reactive monomer in the above content range, it is easy to form a new network structure.

[0086]

[0087] The above step 1 controls the reaction temperature to a temperature of 80°C to 100°C. Preferably, the reaction temperature of the above 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.

[0088] Additionally, the step 1 is performed at a pressure of 5 torr to 20 torr. Preferably, the step 1 is 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.

[0089] In addition, the reaction time of the above step 1 can be appropriately considered in consideration of the molecular weight, yield, etc. of the oligomer produced, and it is preferably performed for 1 to 3 hours.

[0090]

[0091] Preferably, step 1 is performed 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 an amount of 0.1 to 0.5 mol% relative to 3-hydroxypropionic acid.

[0092]

[0093] (Step 2)

[0094] Step 2 of the present invention is a step of further polymerizing the oligomer of step 1 to produce a poly(3-hydroxypropionate) polymer having a novel network structure.

[0095] Through the above steps, a first repeating unit derived from a poly(3-hydroxypropionate) polymer is formed, wherein the first repeating unit includes a plurality of -hydroxypropionate-derived 1-1 repeating units represented by the chemical formula 1.

[0096] [Chemical Formula 1]

[0097]

[0098] The above reactive monomer functions to link multiple 1-1 repeating units formed by 3-hydroxypropionic acid so that the polymer can form a novel network.

[0099]

[0100] Step 2 above can be performed at a lower pressure, unlike step 1, because the reactant is an oligomer.

[0101] Preferably, the reaction temperature of step 2 is 75°C to 95°C. More preferably, the reaction temperature of 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.

[0102] Preferably, the reaction pressure of step 2 is 5 torr or less. More preferably, the pressure of step 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.

[0103] In addition, the reaction time of the above step 2 can be appropriately considered in consideration of the molecular weight, yield, etc. of the poly(3-hydroxypropionate) polymer produced, and is preferably performed for 5 to 30 hours.

[0104] Preferably, steps 1 and 2 are performed for a total of 7 to 30 hours, more preferably 7 to 24 hours.

[0105]

[0106] Meanwhile, since step 2 is performed subsequent to 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 in step 2.

[0107] Additionally, according to one embodiment of the invention, the second step may be performed by additionally introducing a tin-based catalyst. Preferably, the tin-based catalyst is SnCl2 or Sn(oct)2. The catalyst is used in an amount of 0.001 to 0.5 mol% relative to 3-hydroxypropionic acid.

[0108]

[0109] (Step 3)

[0110] Next, a third step is included in which the poly(3-hydroxypropionic acid) polymer and lactide are subjected to ring-opening polymerization to produce a poly(lactic acid-3-hydroxypropionic acid) copolymer.

[0111] Through the above steps, a second repeating unit derived from lactide represented by the following chemical formula 2 is formed:

[0112] [Chemical Formula 2]

[0113] .

[0114]

[0115] The above lactide can be mixed in an amount of 100 to 1,000 parts by weight relative to 100 parts by weight of the poly(lactic acid-3-hydroxypropionic acid) copolymer, and preferably 300 to 1,000 parts by weight, or 500 to 900 parts by weight. When mixed in the above range and a ring-opening reaction is performed, a novel network structured copolymer with excellent physical properties can be produced in the desired molecular weight range, which is preferable.

[0116]

[0117] Step 3 above controls the reaction temperature to a temperature of 100°C to 250°C. Preferably, the reaction temperature of step 3 is 150°C or higher, 160°C or higher, 170°C or higher, or 180°C or higher, and 240°C or lower, 230°C or lower, 220°C or lower, 210°C or lower, or 200°C or lower.

[0118] Additionally, the above step 3 is performed at atmospheric pressure (approximately 760 torr).

[0119] In addition, the reaction time of the above step 3 can be appropriately considered in consideration of the molecular weight, yield, etc. of the final copolymer produced, and it is preferably performed for 1 to 3 hours.

[0120]

[0121] Preferably, step 3 may be performed by additionally adding a tin-based catalyst. Preferably, the tin-based catalyst is SnCl2 or Sn(oct)2. The catalyst is used in an amount of 0.001 to 0.5 mol% relative to lactide.

[0122]

[0123] Meanwhile, the 3-hydroxypropionic acid, reactive monomer, and lactide may be independently pretreated at 30°C to 100°C and 30 mbar to 150 mbar, respectively, before steps 1, 2, and 3, as needed. Through the pretreatment step, moisture present in the 3-hydroxypropionic acid, reactive monomer, and lactide can be removed.

[0124]

[0125] The novel poly(lactic-3-hydroxypropionic acid) polymer having a network structure manufactured according to the above-described method can exhibit appropriate molecular weight characteristics, a high degree of crosslinking, and appropriate elasticity at the same time. Typically, polymers with a high degree of crosslinking exhibit brittle characteristics, but the polymer having a novel network structure according to the present invention has elasticity supplemented by empty spaces within the network structure, thereby reducing brittle characteristics, and thus is easily applicable to various product groups.

[0126]

[0127] As described above, the present invention can effectively produce a poly(lactic acid-3-hydroxypropionic acid) copolymer having a novel network structure and excellent physical properties.

[0128]

[0129] Hereinafter, embodiments of the present invention will be described in more detail in the following examples. However, the following examples are merely illustrative of embodiments of the present invention, and the content of the present invention is not limited by the following examples.

[0130]

[0131] [Examples and Comparative Examples]

[0132] Example 1

[0133] (Step 1)

[0134] 3-Hydroxypropionic acid (70 g) from which moisture had been removed, 7.156 g of the reactive monomer glycerol (10 mol% compared to 3-HP), and 4.59 g of succinic acid (5 mol% compared to 3-HP) were placed in a reactor, and 295.6 mg of p-TSA (p-Toluenesulfonic acid) (0.2 mol% compared to 3-HP) as a catalyst was added. The temperature and pressure inside the reactor were maintained at 90°C and 10 mbar (7.5 torr), respectively, and the reaction was conducted for 2 hours to produce an oligomer.

[0135] (Step 2)

[0136] Next, the temperature and pressure in the reactor were adjusted to 80°C and 0.1 torr, respectively, and SnOct2157.4 mg (0.05 mol% compared to 3-HP) was added as an additional catalyst, and the reaction was continued for an additional 5 hours to produce a poly(3-hydroxypropionic acid) polymer.

[0137] (Step 3)

[0138] Next, 4 g of the poly(3-hydroxypropionic acid) polymer was mixed with 40 g of lactide in a new reactor, and the mixture was dried at room temperature for 12 hours. 180 μl of a 0.01 M toluene solution of Sn(Oct)2 (0.03 mol% based on lactide) was injected into the reactor, and the toluene was vacuum-dried for 30 minutes. Next, the reactor was filled with nitrogen, and the reaction was performed for 90 minutes in an oil bath preheated to 180°C, to obtain a product including a poly(lactic acid-3-hydroxypropionic acid) copolymer having a novel network structure. To remove residual lactide in the product, development was performed at 140°C for 4 hours, thereby preparing the final copolymer.

[0139]

[0140] Examples 2 to 4

[0141] A poly(lactic acid-3-hydroxypropionic acid) copolymer was prepared using the same method as in Example 1, but the reaction conditions were changed as shown in Table 1 below.

[0142]

[0143] Comparative Example 1

[0144] (Step 1)

[0145] 3-Hydroxypropionic acid (60 g) from which moisture had been removed was placed in a reactor, and 253.4 mg (0.2 mol% relative to 3-HP) of p-TSA (p-Toluenesulfonic acid) was added as a catalyst. The temperature and pressure inside the reactor were maintained at 90°C and 10 mbar (7.5 torr), respectively, and the reaction was conducted for 2 hours to produce a 3-hydroxypropionic acid oligomer.

[0146] (Step 2)

[0147] Next, the temperature and pressure inside the reactor were adjusted to 80°C and 0.1 torr, respectively, and the reaction was performed for 5 hours to produce a linear poly(3-hydroxypropionate) polymer.

[0148] (Step 3)

[0149] Next, 40 g of lactide was mixed with 4 g of the poly(3-hydroxypropionic acid) polymer 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% based on lactide) was injected into the reactor, and the toluene was vacuum-dried for 30 minutes. Next, the reactor was filled with nitrogen, and the reaction was performed for 90 minutes in an oil bath preheated to 180°C, obtaining a product including a poly(lactic acid-3-hydroxypropionic acid) copolymer. To remove residual lactide in the product, devolatilization was performed at 140°C for 4 hours, thereby preparing the final copolymer.

[0150]

[0151] Comparative Example 2

[0152] (Step 1)

[0153] 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 295.6 mg of p-TSA (0.2 mol% relative to 3HP) was used as a catalyst to conduct an oligomerization reaction at 90°C and 10 mbar (7.5 torr) for 2 hours.

[0154] (Step 2)

[0155] Next, the temperature and pressure in the reactor were adjusted to 80°C and 0.1 torr, respectively, and Sn(Oct)2157.4 mg (0.05 mol% compared to 3HP) was added as a cocatalyst, and the reaction was further performed for 5 hours to produce a branched polymer.

[0156] (Step 3)

[0157] Next, 40 g of lactide was mixed with 4 g of the branched type 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% based on lactide) was injected into the reactor, and the toluene was vacuum-dried for 30 minutes. Next, the reactor was filled with nitrogen, and the reaction was performed for 90 minutes in an oil bath preheated to 180°C, to obtain a product including a poly(lactic acid-3-hydroxypropionic acid) copolymer having a novel network structure. To remove residual lactide in the product, devolatilization was performed at 140°C for 4 hours, thereby preparing the final copolymer.

[0158] Classification Reactive monomer (content (relative to 3-HP) A (mol%) B (mol%) Example 1 10 5 Example 2 5 2.5 Example 3 10.5 Example 40.5 0.25 Comparative Example 1--Comparative Example 25- Reactive monomer type A: Glycerol B: Succinic acid

[0159] [Experimental Example]

[0160] (1) Molecular weight characteristic evaluation

[0161] For each stage of the copolymers manufactured in the above examples and comparative examples, the weight average molecular weight, number average molecular weight, and polydispersity index were measured by gel permeation chromatography (GPC: gel permeation chromatography, Waters Alliance e2695), and the results are shown in Table 2 below.

[0162] - Solvent: chloroform (eluent)

[0163] - Flow rate: 1.0 ml / min

[0164] - Column temperature: 40℃

[0165] - Standard: Polystyrene

[0166] Classification Molecular Weight Characteristics Evaluation MnMwPDI Example 137,403 201,9365.39 Example 268,880 167,6492.43 Example 361,659 313,1725.08 Example 466,855 162,2042.41 Comparative Example 166,263 168,1362.54 Comparative Example 251,728 226,8405.16

[0167] (2) Alpha value evaluation according to the light scattering detector (MALS)

[0168] For the copolymers manufactured in the above examples and comparative examples, the Alpha value was measured using a light scattering detector (MALS), and the results are shown in Table 1 below.

[0169] First, the copolymer was dissolved in chloroform (Stabilized with ETOH) at a concentration of 5 mg / mL to prepare a sample, and the mobile phase was prepared by filtering 1000 mL of chloroform (Stabilized with ETOH) using a solvent clarification system. The radius of gyration (Rg) of the solvated chain of the polymer was measured using a MALS light scattering detector, and a plot of intrinsic viscosity (η) and absolute molecular weight (M; Absolute MW) was derived from this. The constant Alpha (α) value was calculated using the Mark-Houwink equation of the following mathematical equation 1, and the results are shown in Table 3 below.

[0170] - RI (Refractive Index) Measurement: DAWN8 (Manufacturer: Wyatt)

[0171] - Visocmeter (viscosity) measurement: Viscostar III (Manufacturer: Wyatt)

[0172] - Light scattering measurement: Optilab T-rEX (Manufacturer: Wyatt)

[0173] - Stationary phase: 2x Agilent PLgel MIXED-B and C, 7.5 x 300 mm, 5 μm

[0174] - Mobile phase: Chloroform (stablized with ETOH) = 100(v / v, %)

[0175] - Flow rate: 1.0 mL / min

[0176] - Fixed temperature: 40 ℃

[0177] - Injection volume: 100 ㎕ (0.45 μm filtered)

[0178] - Analysis time: 35 minutes

[0179] - System calibration: Polystyrene (Mp:135700)

[0180] - Chloroform refractive index: 1.45

[0181] [Mathematical Formula 1]

[0182] log[η] = αlogM + logK

[0183] In the above mathematical formula 1,

[0184] [η] is the intrinsic viscosity (㎗ / g) of the copolymer,

[0185] M is the absolute molecular weight (Absolute MW) of the copolymer,

[0186] K is a constant.

[0187] ClassificationAlpha Example 10.4 Example 20.4 Example 30.7 Example 40.5 Comparative Example 11.1

[0188] (3) DSC (differential scanning calorimetry) thermal property evaluation

[0189] For the copolymers manufactured in the above examples and comparative examples, thermal properties (Tg, Tm, cold crystallization (2nd heating result), Tc (1st cooling result)), and total enthalpy (ΔH)) were measured in a nitrogen gas flow state using a TA DSC250 model equipment, and the results are shown in Table 2 below.

[0190] Heat up from 40℃ to 190℃ at 5℃ / min (1st heating) / maintain temperature at 190℃ for 10 minutes

[0191] Cooling from 190℃ to -60℃ at 5℃ / min (1st cooling) / Temperature maintained at -60℃ for 10 minutes

[0192] -Heat increase from -60℃ to 190℃ at 5℃ / min (2 nd heating)

[0193] Classification TcTgCold crystallizationTmTemperature ( o C)ΔH (J / g)Temperature ( oC)Temperature ( o C)ΔH (J / g)Temperature ( o C)ΔH (J / g)Example 2115.183843.05N.DND169.5139.85Example 3112.1137.9152.88N.DN.D168.741.58Example 495.4629.0350.63N.DN.D168.741.58Comparative Example 291.175.6249.1105.424.17159.733.7

[0194] In general, when the crystallization rate is fast, the enthalpy of Tc is large and cold crystallization is little or absent, and the higher the crystallinity, the larger the enthalpy of Tm can be. In addition, when the crystallinity is high, the strength of the material increases, but it is brittle and inelastic. However, in the case of a novel network structure such as the present invention, it can be confirmed that the brittle characteristics can be reduced by lowering the crystallinity. In the case of Comparative Example 2, it was confirmed that the enthalpy of Tc was significantly lower than in the Example, and cold crystallization occurred. Through this, it was confirmed that the speed of crystal formation was slower than in the Example. In addition, it was confirmed that the degree of crystallization was lower than in the Example through the enthalpy value of Tm.

Claims

DEPCT691. A poly(lactic acid-3-hydroxypropionic acid) copolymer composed of: a first repeat derived from a poly(3-hydroxypropionic acid) crosslinked polymer; and a second repeat derived from a lactide denoted by the following chemical formula 2, in which more than one 1-1 repeat derived from 3-hydroxypropionic acid, denoted by the following chemical formula 1, are incorporated within the first repeat where the crosslinked structure is formed by the formation of one of the group bonds.

1. A poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1, in which: the network structure includes at least two branched structures formed by the formation of at least three or more 1-1 repeating units; 3.Poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1, where: the reactive monomer includes at least one reactive terminal substituent chosen from groups consisting of hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), cyano (-CN), thiol (-SH), and isocyanate (-N=C=O) groups.

4. Poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 1, where: the reactive monomer is at least 1. One of the most selected from among the poly(lactic acid-3-hydroxypropionic acid) copolymers under claim 4, where: the polyC1-60 alkylene polyol is at least one of the following: glycerol, poly(ethylene glycol)n=2~15 3-branch, poly(ethylene glycol)n=2~10 4-branch, erythritol, pentaerythritol, di(trierythritol-propane), xylitol, sorbitol, tripentaerythritol, inositol and beta-cyclodextrin. 6.Poly(lactic acid-3-hydroxypropionic acid) copolymer according to claim 4, where: C1-60 alkyl dicarboxylic acid is at least one of the selected group consisting of malonic acid, succinic acid, adipic acid, 1,3,5-benzene tricarboxylic acid, 1,3,5-triazine-2,4,6-tricarboxylic acid, citric acid and 2,2-bis(hydroxymethyl)butyric acid.

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

8. Copolymer Poly(lactic acid-3-hydroxypropionic acid) copolymers according to claim 1, where: the numerical mean molecular weight (Mn) of the copolymer is 10,000 to 250,0009. Poly(lactic acid-3-hydroxypropionic acid) copolymers according to claim 1, where: the mixed dispersion index (PDI) of the copolymer is 2.0 to 7.

010. Poly(lactic acid-3-hydroxypropionic acid) copolymers according to claim 1, where: the crystallization temperature (Tc) of the copolymer is 90 to 120 °C, and the total enthalpy (delta H) in this region is 20 to 40 joules / gram11.

12. The method for the preparation of the poly(lactic acid-3-hydroxypropionic acid) copolymer as defined in claim 1, which includes: the first step of polymerization of 3-hydroxypropionic acid and monomers. The reactive polymerization process involves two steps: the first is polymerization to form oligomers; the second is polymerization to prepare a poly(3-hydroxypropionic acid) crosslinked polymer; and the third is ring-opening polymerization of the poly(3-hydroxypropionic acid) polymer and lactide to prepare a poly(lactic acid-3-hydroxypropionic acid) copolymer.13Method for the preparation of poly(lactic acid-3-hydroxypropionic acid) copolymers pursuant to claim paragraph 12, where: the reactive monomer includes at least one reactive terminal substituent chosen from groups consisting of hydroxyl(-OH), carboxyl(-COOH), amino(-NH2), cyano(-CN), thiol(-SH), and isocyanate(-N=C=O) groups.

14. Method for the preparation of poly(lactic acid-3-hydroxypropionic acid) copolymers pursuant to claim paragraph 12, where: the reactive monomer includes at least one reactive terminal substituent chosen from groups consisting of hydroxyl(-OH), carboxyl(-COOH), amino(-NH2), cyano(-CN), thiol(-SH), and isocyanate(-N=C=O) groups. The reactive agent is at least one of the selected from among the poly(lactic acid-3-hydroxypropionic acid) poly(C1-60 alkyl dicarboxylic acid)15.Method for the preparation of poly(lactic acid-3-hydroxypropionic acid) copolymers according to claim 14, where: polyC1-60 alkyl polyol is present in an amount of 0.1 to 15 percent by mol relative to 100 mol of 3-hydroxypropionic acid, and C1-60 alkyl dicarboxylic acid is present in an amount of 0.01 to 5 percent by mol relative to 100 mol of 3-hydroxypropionic acid;.