Poly(3-hydroxypropionic acid) block copolymers, their manufacturing method, and articles containing the same

Abstract

The poly(3-hydroxypropionic acid) block copolymer according to the present invention has the characteristic that it can improve various physical properties such as thermal properties, crystallinity, and tensile properties of biodegradable polymers by introducing 3-hydroxypropionic acid and lactone monomer or additionally lactide monomer, thereby expanding the field of application.

Description

[Technical Field]

[0001] Cross-reference to related application(s) This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0102547 filed on August 4, 2021, and Korean Patent Application No. 10-2022-0096678 filed on August 3, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to block copolymers of poly(3-hydroxypropionic acid), methods for making same, and articles containing same. [Background technology]

[0003] Poly(3-hydroxypropionic acid) is a biodegradable polymer that is not only durable but also has excellent mechanical properties, making it an attractive eco-friendly material.

[0004] Poly(3-hydroxypropionic acid) is produced by condensation polymerization of the monomer 3-hydroxypropionic acid (3-HP), and for industrial applicability, poly(3-hydroxypropionic acid) with excellent thermal stability must be produced. However, the chain of poly(3-hydroxypropionic acid) contains an ester structure, and the thermal decomposition temperature of this ester structure is approximately 220°C, so there is a limit to how much thermal stability can be improved.

[0005] Furthermore, although it is possible to produce high molecular weight poly(3-hydroxypropionic acid) and improve thermal stability, a low molecular weight cyclic structure is formed during the condensation polymerization of 3-hydroxypropionic acid, which not only makes it impossible to produce high molecular weight poly(3-hydroxypropionic acid) but also reduces the production yield of poly(3-hydroxypropionic acid).

[0006] Therefore, the present inventors have confirmed that when a copolymer is produced by adding lactone, lactide, or a combination thereof to 3-hydroxypropionic acid as a monomer, the thermal properties, crystallinity, and tensile properties of the biodegradable polymer produced can be controlled by varying the number of carbon atoms in the lactone ring, the presence or absence of branching, and the type of branched chain, and thus completed the present invention. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a block copolymer of poly(3-hydroxypropionic acid) that has controlled thermal and tensile properties while maintaining the inherent properties of polypropionic acid, and a method for producing the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following block copolymer of poly(3-hydroxypropionic acid).

[0009] The poly(3-hydroxypropionic acid) block copolymer of the present invention comprises a repeating unit of 3-hydroxypropionic acid, which is represented by the following chemical formula 1; and a repeating unit of lactone, which is represented by the following chemical formula 2, wherein the number of repeating units (m) in the following chemical formula 1 is an integer of 100 to 5000, the number of repeating units (n) in the following chemical formula 2 is an integer of 100 to 5000, and L in the following chemical formula 2 is a linear or branched alkyl group having 3 to 10 carbon atoms. [ka]

[0010] In addition, the method for producing a block copolymer of poly(3-hydroxypropionic acid) of the present invention includes a step of polymerizing 3-hydroxypropionic acid to produce a 3-hydroxypropionic acid oligomer (Step 1); a step of polymerizing the 3-hydroxypropionic acid oligomer to produce poly(3-hydroxypropionic acid) (Step 2); and a step of ring-opening polymerizing a lactone having 3 to 10 carbon atoms using the poly(3-hydroxypropionic acid) as an initiator (Step 3). [Effects of the Invention]

[0011] As described above, the poly(3-hydroxypropionic acid) block copolymer according to the present invention is characterized in that it can improve various physical properties of biodegradable polymers, such as thermal properties, crystallinity, and tensile properties, by introducing a lactone-derived monomer, a lactide-derived monomer, or a combination thereof in addition to 3-hydroxypropionic acid, thereby expanding its application fields. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention provides a block copolymer of poly(3-hydroxypropionic acid). The block copolymer of poly(3-hydroxypropionic acid) of the present invention will be described in detail below.

[0013] First, the poly(3-hydroxypropionic acid) block copolymer of the present invention comprises a repeating unit of 3-hydroxypropionic acid, which is represented by the following chemical formula 1; and a repeating unit of lactone, which is represented by the following chemical formula 2, wherein the number of repeating units (m) in the following chemical formula 1 is an integer of 100 to 5000, the number of repeating units (n) in the following chemical formula 2 is an integer of 100 to 5000, and L in the following chemical formula 2 is a linear or branched alkyl group having 3 to 10 carbon atoms. [ka]

[0014] An example of a poly(3-hydroxypropionic acid) block copolymer containing the repeating unit of Chemical Formula 1 and the repeating unit of Chemical Formula 2 may be Chemical Formula 4 below. [ka]

[0015] In addition, when ε-caprolactone is used as the lactone repeating unit of Chemical Formula 2, Chemical Formula 4 can be represented by the following Chemical Formula 4-1. [ka]

[0016] In addition, when γ-octanoic lactone is used as the lactone repeating unit of Chemical Formula 2, Chemical Formula 4 can be represented by the following Chemical Formula 4-2. [ka]

[0017] The block copolymer of poly(3-hydroxypropionic acid) further includes a repeating unit of lactide represented by the following Chemical Formula 3, where the number of repeating units (1) in the following Chemical Formula 3 may be an integer of 100 to 5,000. [ka]

[0018] An example of a poly(3-hydroxypropionic acid) block copolymer further comprising the repeating unit of Formula 3 may be Formula 5 below. [ka]

[0019] The term "poly(3-hydroxypropionic acid) block copolymer" as used herein refers to a block copolymer obtained by polymerizing a lactone-derived monomer, a 3-hydroxypropionic acid-derived monomer, and an additional lactide-derived monomer in block units. In particular, by introducing a lactone-derived monomer, the crystallization characteristics can be controlled by the number of carbon atoms in the lactone ring and the presence or absence of a branched structure, thereby adjusting the crystallization and tensile properties.

[0020] Furthermore, unlike existing PLA (polylactic acid), the present invention is characterized in that it necessarily contains 3-hydroxypropionic acid monomer, and also contains lactone-derived monomers, lactide-derived monomers, or a combination thereof.

[0021] The present invention also provides a method for producing a block copolymer of the aforementioned poly(3-hydroxypropionic acid), comprising the following steps: polymerizing a 3-hydroxypropionic acid polymer and a lactone using a catalyst.

[0022] The 3-hydroxypropionic acid polymer means a homopolymer of 3-hydroxypropionic acid.

[0023] Specifically, the method for producing poly(3-hydroxypropionic acid-b-lactone) of the present invention includes the steps of: polymerizing 3-hydroxypropionic acid to produce a 3-hydroxypropionic acid oligomer (Step 1); polymerizing the 3-hydroxypropionic acid oligomer to produce poly(3-hydroxypropionic acid) (Step 2); and ring-opening polymerizing a lactone having 3 to 10 carbon atoms using the poly(3-hydroxypropionic acid) as an initiator (Step 3).

[0024] The above (Step 3) may further include lactide as a monomer.

[0025] When lactide is further included as a monomer in step 3, the lactide may be included in an amount of 40 to 99 parts by weight, based on 100 parts by weight of the total weight of the lactone and lactide. For example, the lactide may be included in an amount of 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, or 70 parts by weight or more to 99 parts by weight or less, 90 parts by weight or less, or 80 parts by weight or less, based on 100 parts by weight of the total weight of the lactone and lactide.

[0026] When lactide is further included as a monomer, if the lactide content is too low, the degree of improvement in the thermal and mechanical properties of the block copolymer may not be large.

[0027] Furthermore, when lactide is further included as a monomer in Step 3, Step 3 can include a step of polymerizing lactide using the poly(3-hydroxypropionic acid) as an initiator (Step 3-1); and a step of ring-opening-polymerizing a lactone having 3 to 10 carbon atoms with the poly(3-hydroxypropionic acid) and lactide polymer (Step 3-2). When lactide is polymerized first and then lactone is polymerized, a block copolymer can be obtained in which 3-hydroxypropionic acid-derived repeating units, lactide-derived repeating units, and lactone-derived repeating units are polymerized to form blocks. Block copolymers differ from random copolymers in that they have higher crystallinity.

[0028] On the other hand, the lactone may be included in an amount of 1 to 60 parts by weight based on 100 parts by weight of the total weight of the lactone and lactide. For example, the lactone may be included in an amount of 1 part by weight or more, 5 parts by weight or more, 10 parts by weight or more, or 20 parts by weight or more to 60 parts by weight or less, 50 parts by weight or less, 40 parts by weight or less, or 30 parts by weight or less based on 100 parts by weight of the total weight of the lactone and lactide.

[0029] In step 3, the poly(3-hydroxypropionic acid) may be present in an amount of 50 parts by weight or less relative to 100 parts by weight of the total reactants. The reactants in step 3 may be poly(3-hydroxypropionic acid) and lactone, or poly(3-hydroxypropionic acid), lactone, and lactide. Specifically, the poly(3-hydroxypropionic acid) in step 3 may be present in an amount of 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 17 parts by weight or less, 10 parts by weight or less to more than 0 parts by weight, 5 parts by weight or more, or 9 parts by weight or more relative to 100 parts by weight of the total reactants.

[0030] If the content of poly(3-hydroxypropionic acid) does not satisfy the above range, the effects of using lactone to improve various physical properties such as thermal properties, crystallinity, and tensile properties may be insignificant.

[0031] The step 2 is a step of polymerizing 3-hydroxypropionic acid oligomer at a pressure of 1 torr or less for 12 to 48 hours, preferably at a pressure of 0.2 torr or less for 22 to 26 hours.

[0032] The lactone having 3 to 10 carbon atoms in step 3 may be at least one selected from the group consisting of ε-caprolactone, β-butyrolactone, β-valerolactone, γ-butyrolactone, δ-valerolactone, γ-valerolactone, trimethylene carbonate, p-dioxanone, δ-hexalactone, δ-caprolactone, mevalonolactone, γ-octanoic lactone, and γ-nonanoic lactone.

[0033] Since the step (3) involves a lactone or, additionally, lactide ring-opening polymerization reaction, it is carried out in the presence of a ring-opening catalyst. For example, the catalyst may be a catalyst represented by Chemical Formula 6.

[0034] [Chemical formula 6] MA 1 p A 2 2-p In the above Chemical Formula 6, M is Al, Mg, Zn, Ca, Sn, Fe, Y, Sm, Lu, Ti or Zr; p is an integer from 0 to 2, A 1 and A 2 are each independently an alkoxy or carboxyl group. More specifically, the catalyst represented by Chemical Formula 6 may be tin(II) 2-ethylhexanoate (Sn(Oct)2).

[0035] Preferably, the amount of the catalyst used may be 0.001 to 10 mol %, 0.01 to 5 mol %, or 0.01 to 1 mol %, assuming that the total number of moles of lactone is 100 mol %.

[0036] Preferably, the (Step 3) is carried out at a temperature of 140 to 190° C. Preferably, the preparation method is carried out for 5 minutes to 10 hours, more preferably for 1 hour to 3 hours.

[0037] The present invention can also provide a resin containing the block copolymer of poly(3-hydroxypropionic acid).

[0038] The present invention also provides a resin composition containing the resin. The resin composition may further contain, in addition to the resin, other additives that improve physical properties.

[0039] The resin composition can be molded into one or more resin molded articles selected from the group consisting of injection molded articles, extrusion molded articles, blow molded articles, films, inflation articles, fibers, nonwoven fabrics, foams, sheets, and the like.

[0040] The present invention also provides an article comprising the aforementioned block copolymer of poly(3-hydroxypropionic acid), which may be an electronic material, a building material, a food packaging material, a food container (such as a disposable cup or tray), an industrial article, an agricultural article (such as a mulching film), or the like.

[0041] The resin, resin composition, and article containing the block copolymer of poly(3-hydroxypropionic acid) may further contain two or more different lactones or additional comonomers depending on the desired physical properties.

[0042] The present invention will be described in more detail in the following examples, but the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0043] Comparative Example 1 The 3-hydroxypropionic acid in the aqueous solution was dried at 90°C and 100 torr to obtain 60 g of dried 3-hydroxypropionic acid. 0.2 mol% of the catalyst p-TSA (p-toluenesulfonic acid) was added to this dried 3-hydroxypropionic acid and reacted at 90°C and 10 torr for 2 hours. The vacuum was then changed to 0.2 torr and the reaction was continued for 5 hours. Then, 0.05 mol% of the catalyst Sn(Oct)2 was added and the reaction continued for a total of 24 hours to obtain poly(3-hydroxypropionic acid) oligomer.

[0044] Example 1 The catalyst Sn(Oct)2 (17 μl, 0.03 mol%) was added to vacuum-dried poly(3-hydroxypropionic acid) (2 g) from Comparative Example 1 and dried ε-caprolactone (20 g) and reacted at 140°C for 3 hours to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0045] Example 2 Vacuum-dried poly(3-hydroxypropionic acid) (2 g) from Comparative Example 1 and dried ε-caprolactone (20 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (17 μl, 0.03 mol%) was added and the mixture was reacted at 140°C for 4 hours to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0046] Example 3 Vacuum-dried poly(3-hydroxypropionic acid) (4 g) from Comparative Example 1 and dried ε-caprolactone (20 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (17 μl, 0.03 mol%) was added and the mixture was reacted at 140°C for 3 hours to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and the product was removed from the reactor and subjected to devolatilization at 50°C for 4 hours to remove residual monomers.

[0047] Example 4 Vacuum-dried poly(3-hydroxypropionic acid) (4 g) from Comparative Example 1 and dried ε-caprolactone (20 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (17 μl, 0.03 mol%) was added and the mixture was reacted at 140°C for 5 hours to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0048] Example 5 Vacuum-dried poly(3-hydroxypropionic acid) (1.88 g) from Comparative Example 1, dried β-butyrolactone (3.84 g), and dried lactide (15 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (14 μl, 0.03 mol%) was added and reacted at 180°C for 1.5 hours to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and subjected to devolatilization at 140°C for 4 hours to remove residual monomers.

[0049] Example 6 Vacuum-dried poly(3-hydroxypropionic acid) (2 g) from Comparative Example 1, dried ε-caprolactone (4 g), and dried lactide (16 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (14 μl, 0.03 mol%) was added and the mixture was reacted at 180°C for 1 hour to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0050] Example 7 Vacuum-dried poly(3-hydroxypropionic acid) (2 g) from Comparative Example 1, dried ε-caprolactone (10 g), and dried lactide (10 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (15 μl, 0.03 mol%) was added and the mixture was reacted at 180°C for 1.5 hours to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0051] Example 8 Vacuum-dried poly(3-hydroxypropionic acid) (2 g) from Comparative Example 1 and dried lactide (16 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (14 μl, 0.03 mol%) was added and reacted at 180°C for 0.5 hours. Then, dried ε-caprolactone (4 g) was added and reacted for an additional 0.5 hours to polymerize the copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0052] Example 9 Vacuum-dried poly(3-hydroxypropionic acid) (2 g) from Comparative Example 1 and dried lactide (10 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (15 μl, 0.03 mol%) was added and reacted at 180°C for 0.5 hours. Dried ε-caprolactone (10 g) was then added and reacted for an additional hour to polymerize the copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0053] Comparative Example 2 Vacuum-dried poly(3-hydroxypropionic acid) (4 g) from Comparative Example 1 and dried lactide (40 g) were placed in a reactor. Then, catalyst Sn(Oct)2 (18 μl, 0.03 mol%) was added and reacted at 180°C for 1 hour to polymerize a copolymer. The polymerized copolymer was vacuum-dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and subjected to devolatilization at 140°C for 4 hours to remove residual monomers.

[0054] Comparative Example 3 The copolymer was polymerized by adding dried ε-caprolactone (40 g) and catalyst Sn(Oct)2 (11 μl, 0.01 mol%) to octanol (110 μl, 0.2 mol%) and reacting at 140°C for 4 hours. The polymerized copolymer was vacuum dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0055] Comparative Example 4 Octanol (140 μL, 0.2 mol%) was mixed with dried β-butyrolactone (5.2 g), dried lactide (20 g), and catalyst Sn(Oct)2 (6 μL, 0.01 mol%) and reacted at 180°C for 1 hour to polymerize the copolymer. The polymerized copolymer was vacuum dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and devolatilized at 140°C for 4 hours to remove residual monomers.

[0056] Comparative Example 5 Dried ε-caprolactone (7.9 g), dried lactide (40 g), and catalyst Sn(Oct)2 (11 μl, 0.01 mol%) were added to octanol (109 μl, 0.2 mol%) and reacted at 190°C for 1 hour to polymerize the copolymer. The polymerized copolymer was vacuum dried at room temperature for 2 hours to remove moisture absorbed during the polymerization, and then the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0057] Comparative Example 6 Dried lactide (40 g) and catalyst Sn(Oct)2 (11 μl, 0.01 mol%) were added to octanol (109 μl, 0.2 mol%) and reacted at 180°C for 1 hour. Then, ε-caprolactone (7.9 g) was added and reacted at 180°C for 1 hour to polymerize the copolymer. The polymerized copolymer was dried under vacuum at room temperature for 2 hours to remove moisture absorbed during the polymerization, and the product was removed from the reactor and devolatilized at 50°C for 4 hours to remove residual monomers.

[0058] The molecular weights and thermal properties of the polymers prepared in Examples 1 to 9 and Comparative Examples 1 to 6 were measured and are shown in Table 1 below. This is to confirm how the thermal properties of copolymers obtained by polymerizing 3-hydroxypropionic acid with lactone or lactone and lactide as comonomers change compared to existing poly(3-hydroxypropionic acid), i.e., whether the thermal properties are adjustable, but is not intended to indicate that a particular polymer is inferior.

[0059] The respective measurement methods are as follows.

[0060] Experiment 1 - GPC measurement A Water E2695 model instrument and an Agilent Plgel mixed c and b column were used. Measurements were performed using chloroform as the eluent at 40°C with a flow rate of 1 ml / min, and relative molecular weights were measured using polystyrene as the standard. Samples were prepared at 4 mg / ml in chloroform as the solvent, and 50 μl was injected and measured.

[0061] Experiment 2 - DSC measurement Measurements were taken using a TA DSC250 model under nitrogen gas flow conditions. The temperature was raised from 40°C to 220°C at a rate of 5°C / min (1 stThe temperature was maintained at 220°C for 10 minutes. After that, the mixture was cooled from 220°C to -70°C at a rate of 5°C / min (1 st The temperature was then increased from -70°C to 220°C at a rate of 5°C / min (2 nd The measurement was performed by heating. [Table 1]

[0062] Comparing Comparative Examples 2 and 3 with Examples 2 to 4, the Tg and Tm of Comparative Example 3 and Examples 2 to 4 were measured to be lower than Comparative Example 2. This is because the content of poly(3-hydroxypropionic acid) was 10 or 20 parts by weight based on 100 parts by weight of the total reactants, and it was confirmed that Examples 2 to 4 followed the thermal properties of Comparative Example 3, which used polycaprolactone. Therefore, it was confirmed that the thermal properties of polylactone were imparted to poly(3-hydroxypropionic acid).

[0063] Comparing Comparative Example 4 and Example 5, the crystallization rate of Example 5 increased (T c It was also confirmed that the enthalpy change during cold crystallization increased from 2.8 J / g to 7.5 J / g, and the enthalpy decreased from 30.1 J / g to 15.1 J / g. Comparing this with Comparative Example 1, it was confirmed that the thermal properties of polylactone and polylactide were imparted to poly(3-hydroxypropionic acid).

[0064] Comparing Comparative Examples 5 and 6 with Examples 6 to 9, when lactide was contained in an amount of 80 parts by weight per 100 parts by weight of the total lactone and lactide (Examples 6 and 8), there was no significant difference between random polymerization and block polymerization of lactide monomers.

[0065] However, when lactide was included at 50 parts by weight per 100 parts by weight of the total lactone and lactide (Examples 7 and 9), Example 9, in which lactide monomer was block polymerized, showed crystallinity, while Example 7, in which lactide monomer was randomly polymerized, showed no measured Tm, confirming that it had a gum-like state without showing crystallinity. In Example 9, in which the same composition was block polymerized, the crystallinity was low (ΔH of Tm was 12.6 J / g), but the Tm was measured.

[0066] Comparing Examples 6 and 8, Example 6, in which lactide monomers were randomly polymerized, had a Tm ΔH of 19.2 J / g, which was lower than the Tm ΔH of Example 8, in which lactide monomers were block polymerized, which was 5.7 J / g.

[0067] Tg, Tm, cold crystallization (2 nd heating result), Tc(1 st From the results of the cold crystallization tests, it was confirmed that the faster the crystallization rate, the larger the enthalpy of Tc, and the lower or no cold crystallization temperature is, and the higher the crystallinity, the larger the enthalpy of Tm. Higher crystallinity generally means higher strength of the material, but it is also brittle and lacks elasticity. However, since elasticity is generally known to be generated by the empty spaces between polymer chains, it is possible to lower the crystallinity and thus the brittleness by using a branched structure as a monomer.

[0068] The mechanical properties of the polymers prepared in Examples 1 to 9 and Comparative Examples 1 to 6 were measured and are shown in Table 2 below.

[0069] The respective measurement methods are as follows.

[0070] Experiment 3: Dogbone workability The dog bone mold was preheated in a heated hot press for 2 minutes, and then the polymer was poured into it and processed for 2 minutes to produce dog bones. The hot press temperature was 90°C for Comparative Examples 1 and 3 and Examples 1 to 4, and 180°C for Comparative Examples 2, 4 to 6 and Examples 5 to 9. The dog bone specifications were length (64 cm), width (1 cm, 0.3 cm), and thickness (1 mm) according to ASTM 638.

[0071] Experiment 4: Mechanical properties The strength, modulus of elasticity, and elongation were measured by pulling the specimen at a speed of 5 mm / min using a 5 kN weight using an Instron 5982 model. The specimen was the processed dog bone.

[0072] Experiment 5: Optical properties UV-visible spectrometer Each specimen was prepared as a sheet with the thickness shown in Table 2, and then attached to a UV-visible spectrophotometer (Agilent 8453) to measure the transmittance, with the transmittance value in the 480 nm region being measured. [Table 2]

[0073] Comparing Comparative Example 3 with Examples 2 and 4, Examples 2 and 4 demonstrated excellent results, with tensile strengths of over 20 MPa and elongations of over 600% achieved through block copolymerization of poly(3-hydroxypropionic acid) and caprolactam. In particular, Examples 2 and 4, which had weight-average molecular weights of over 100,000 g / mol, demonstrated excellent strength and elongation. Example 1 had the same monomer composition, catalyst type, amount, and reaction temperature as Example 2, but a shorter reaction time of 3 hours than Example 2. Therefore, the tensile strength and elongation of Example 1 were inferior to those of Example 2. This is due to the smaller molecular weight of Example 1, which required a shorter reaction time, resulting in less interchain entanglement. Example 3 also had the same monomer composition, catalyst type, amount, and reaction temperature as Example 4, but a shorter reaction time of 3 hours than Example 4. This indicates that the tensile strength and elongation of Example 3 are inferior to those of Example 4, which is also due to the fact that Example 3, which also had a shorter reaction time, had a smaller molecular weight and less inter-chain entanglement.

[0074] Comparing Comparative Example 4 and Example 5, it was confirmed that Example 5 had improved thermal processability due to the block copolymerization of butyrolactone with poly(3-hydroxypropionic acid) compared to Comparative Example 4, which was brittle and unable to be thermally processed. In addition, in Example 5, the copolymerized butyrolactone was harder than lactide, and the measured elongation was very low.

[0075] Comparing Comparative Examples 5 and 6 with Examples 6 to 9, it was confirmed that copolymerizing poly(3-hydroxypropionic acid) in addition to caprolactone and lactide maintained transparency while increasing elongation from 300% to 600%. However, in the case of the non-crystalline sample of Example 7, it behaved like a gum at room temperature, making it difficult to prepare dog bones, and as a result, it was not possible to confirm the mechanical properties. In the case of Example 9, dog bones could be prepared, but due to low crystallinity, defects occurred during dog bone preparation, resulting in poor mechanical properties.

[0076] In addition, comparing Examples 6 and 8 with Examples 7 and 9, it was confirmed that the tensile strength and elongation can be adjusted by adjusting the mixing ratio of lactone and lactide. It was also confirmed that the processability, strength, and elongation can be adjusted by changing the structure, whether it is random or block.

Claims

1. Step 1: polymerizing 3-hydroxypropionic acid to produce 3-hydroxypropionic acid oligomers; polymerizing the 3-hydroxypropionic acid oligomer to produce poly(3-hydroxypropionic acid) (Step 2); and Step 3: Ring-opening polymerizing a lactone having 3 to 10 carbon atoms using the poly(3-hydroxypropionic acid) as an initiator; Including, (Step 3) further includes lactide as a monomer; Method for producing block copolymers of poly(3-hydroxypropionic acid).

2. The lactide is contained in an amount of 40 to 99 parts by weight based on 100 parts by weight of the total weight of lactone and lactide. A method for producing a block copolymer of poly(3-hydroxypropionic acid) according to claim 1.

3. In step 3, poly(3-hydroxypropionic acid) is contained in an amount of 50 parts by weight or less based on 100 parts by weight of the total reactants. A method for producing a block copolymer of poly(3-hydroxypropionic acid) according to claim 1.

4. The lactone having 3 to 10 carbon atoms in Step 3 is ε-caprolactone, β-butyrolactone, β-valerolactone, γ-butyrolactone, δ-valerolactone, γ-valerolactone, trimethylene carbonate, p-dioxanone, δ-hexalactone, δ-caprolactone, mevalonolactone, γ-octanoic lactone lactone, and γ-nonanoic lactone, A method for producing a block copolymer of poly(3-hydroxypropionic acid) according to claim 1.

5. Step 2 is a step of polymerizing 3-hydroxypropionic acid oligomer under a pressure of 1 torr or less. A method for producing a block copolymer of poly(3-hydroxypropionic acid) according to claim 1.

6. Step 3 is a step of ring-opening polymerization at a temperature of 140 to 190°C. A method for producing a block copolymer of poly(3-hydroxypropionic acid) according to claim 1.

7. A repeating unit of 3-hydroxypropionic acid, represented by the following chemical formula 1: A repeating unit of the following chemical formula 2, which is a repeating unit of lactone, and It contains a repeating unit of the following chemical formula 3, which is a repeating unit of lactide, The number of repeating units (m) in the following chemical formula 1 is an integer of 100 to 5000, The number of repeating units (n) in the following chemical formula 2 is an integer of 100 to 5000, The number of repeating units (l) in the following chemical formula 3 is an integer of 100 to 5000, In the following formula 2, L is a linear or branched alkyl group having 3 to 10 carbon atoms, Produced by the method of any one of claims 1 to 6. Block copolymer of poly(3-hydroxypropionic acid). 【Chemistry 1】 【change】

8. A block copolymer of poly(3-hydroxypropionic acid) according to claim 7, resin.

9. The resin according to claim 8, Resin composition.

10. The resin composition is molded into one or more resin molded articles selected from the group consisting of an injection molded article, an extrusion molded article, a blow molded article, an inflation molded article, a fiber, a nonwoven fabric, a foam, a sheet, and a film. The resin composition according to claim 9.

11. An article comprising the block copolymer of poly(3-hydroxypropionic acid) of claim 7.

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