Block copolymer and method for producing the same

Abstract

The present invention relates to block copolymers that have excellent mechanical properties combined with environmental friendliness and biodegradability properties.

Description

[Technical Field]

[0001] Cross-reference to related application(s) This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0113916 dated August 27, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to block copolymers that have excellent mechanical properties combined with environmental friendliness and biodegradability. [Background technology]

[0003] Polyglycolic acid (PGA) is a type of aliphatic polyester that has attracted attention as an environmentally friendly material that is biodegradable and has excellent tensile strength and elastic modulus.

[0004] Unlike the currently used petroleum-based resins such as polystyrene resin, polyvinyl chloride resin, and polyethylene, it has the effect of preventing the depletion of petroleum resources and suppressing carbon dioxide emissions, thereby reducing the environmental pollution that is a drawback of petroleum-based plastic products. Therefore, as the issue of environmental pollution caused by waste plastics has emerged as a social problem, efforts are being made to expand the scope of application to product areas that use general plastics (petroleum-based resins), such as food packaging materials and containers, and electronic product cases.

[0005] However, compared to existing petroleum-based resins, polyglycolic acid has poor elongation to break properties and exhibits brittleness, which limits its processability and limits its use as a general-purpose resin.

[0006] Therefore, in order to overcome the above drawbacks, the present inventors have confirmed that a block copolymer in which 3-hydroxypropionic acid (3HP) is introduced into polyglycolic acid has the effect of improving mechanical properties while maintaining the inherent properties of polyglycolic acid, and have 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 having improved elongation while maintaining the inherent properties of polyglycolic 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 a block copolymer represented by the following Chemical Formula 1: [ka]

[0009] In the above Chemical Formula 1, R 1 , and R 2 are each independently hydrogen, N, O, S, substituted or unsubstituted C 1-20 is alkyl, X 1 , and X 2 are each independently a direct bond, —COO—, —NR′CO—, —(NR′)(COO)—, —R′NCONR′—, or —OCOO-; R' is independently hydrogen, C 1-20 is alkyl, L is a substituted or unsubstituted C 1-10 Alkylene; substituted or unsubstituted C 6-60 arylene; or C containing one or more heteroatoms selected from the group consisting of substituted or unsubstituted N, O, and S 2-60 is heteroarylene, m and n are each independently an integer of 1 to 10,000.

[0010] The block copolymer of the present invention is a block copolymer obtained by polymerizing a 3-hydroxypropionic acid-derived monomer and a glycolide-derived monomer as represented by Chemical Formula 1 above, and in particular, refers to a block copolymer in which various physical properties such as elongation of polyglycolic acid are controlled by introducing a 3-hydroxypropionic acid-derived monomer.

[0011] When a 3-hydroxypropionic acid-derived monomer is introduced as a comonomer into polyglycolic acid, various physical properties of the polyglycolic acid can be improved, but the physical properties exhibited vary depending on the linkage structure of each repeating unit and the degree to which each repeating unit is introduced. Therefore, in the present invention, the mechanical properties of polyglycolic acid are adjusted while maintaining the inherent physical properties of polyglycolic acid by adjusting the linkage structure of each repeating unit and the degree to which the 3-hydroxypropionic acid-derived monomer is introduced.

[0012] The present invention will be described in detail below.

[0013] In the present invention, terms such as "first" and "second" are used to describe various components, and the terms are used only to distinguish one component from another.

[0014] A block copolymer according to one embodiment of the present invention comprises a first block containing repeating units derived from 3-hydroxypropionic acid (hereinafter referred to as 3HP) and a second block containing repeating units polymerized from glycolic acid. The first and second blocks are linked by direct bonds, ester bonds, amide bonds, urethane bonds, or carbonate bonds, thereby overcoming the drawback of low elongation properties of biodegradable resins containing only polyglycolic acid. Furthermore, these copolymers have excellent biodegradability while complementing the mechanical properties of their respective homopolymers.

[0015] Specifically, a block copolymer according to one embodiment of the present invention includes a first block which is a 3HP-derived repeating unit represented by the following Chemical Formula 2, and a second block which is a glycolide-derived repeating unit represented by the following Chemical Formula 3: [ka] [ka]

[0016] The 3HP-derived repeating unit represented by Chemical Formula 2 has the advantages of excellent mechanical properties and high elongation to break due to a low glass transition temperature (Tg) of approximately -20°C. Therefore, when such poly(3-hydroxypropionate) (P3HP) and polyglycolic acid (PGA) are chemically bonded to produce a block copolymer, a biodegradable material with excellent mechanical properties can be produced.

[0017] In addition, the repeating unit represented by Chemical Formula 2 and the repeating unit represented by Chemical Formula 3 may be linked by a direct bond, an ester bond, an amide bond, a urethane bond, a urea bond, or a carbonate bond. Specifically, in Chemical Formula 1, X1 and X2 are each independently a direct bond, -COO-, -NR'CO-, -(NR')(COO)-, -R'NCONR'-, or -OCOO-. In this case, R' is each independently hydrogen, C 1-20 It is alkyl.

[0018] In addition, in the above formula 1, L is a direct bond; a substituted or unsubstituted C 1-10 Alkylene; substituted or unsubstituted C 6-60 arylene; or C containing one or more heteroatoms selected from the group consisting of substituted or unsubstituted N, O, and S 2-60 It is heteroarylene.

[0019] In Chemical Formula 1, n and m are each independently an integer of 1 to 10,000. n refers to the number of repeating units derived from 3HP, and by incorporating the repeating units within this range, it is possible to adjust physical properties such as elongation while maintaining the inherent physical properties of polyglycolic acid. m refers to the number of repeating units derived from glycolic acid.

[0020] Preferably, X1, X2, and L are direct bonds.

[0021] Preferably, the formula 1 is represented by the following formula 1-1: [ka]

[0022] In the above Chemical Formula 1-1, n and m are as defined in Chemical Formula 1.

[0023] Preferably, n is 10 to 700, and m is 10 to 700. More preferably, n is 20 or more, 30 or more, 40 or more, 50 or more, or 60 or more, and 650 or less, 600 or less, 550 or less, 500 or less, or 450 or less.

[0024] More preferably, m is 20 or more, 30 or more, 40 or more, 50 or more, or 60 or more, and 650 or less, 600 or less, 550 or less, 500 or less, or 450 or less.

[0025] Preferably, the weight-average molecular weight of the block copolymer according to the present invention is 10,000 g / mol to 500,000 g / mol, more preferably 12,000 g / mol or more, 15,000 g / mol or more, 20,000 g / mol or more, 25,000 g / mol or more, or 30,000 g / mol or more; and 480,000 g / mol or less, 460,000 g / mol or less, 440,000 g / mol or less, or 420,000 g / mol or less.

[0026] The present invention also provides a method for producing the aforementioned block copolymer, comprising the following steps: preparing poly(3-hydroxypropionate) (Step 1); and preparing the block copolymer by ring-opening polymerization of glycolide monomer in the presence of a poly(3-hydroxypropionate) initiator (Step 2).

[0027] Step 1 is a step of preparing poly(3-hydroxypropionate), which means a homopolymer of 3-hydroxypropionic acid, and is prepared by controlling the degree of polymerization in consideration of the ranges of n and m described above.

[0028] Preferably, the poly(3-hydroxypropionate) of Step 1 has a weight-average molecular weight of 1,000 g / mol to 500,000 g / mol. More preferably, the poly(3-hydroxypropionate) has a weight-average molecular weight of 1,200 g / mol or more, 1,500 g / mol or more, 1,700 g / mol or more, or 2,000 g / mol or more, and may have a weight-average molecular weight of 250,000 g / mol or less, 100,000 g / mol or less, or 50,000 g / mol or less.

[0029] Step 2 is a step of ring-opening polymerization of glycolide monomer using poly(3-hydroxypropionate) as an initiator.

[0030] Step 2 can be carried out by bulk polymerization without substantially using a solvent. "Substantially using no solvent" can refer to the use of a small amount of solvent to dissolve the catalyst, for example, up to 1 ml of solvent per 1 kg of monomer used. By carrying out Step 2 by bulk polymerization, it is possible to omit processes such as solvent removal after polymerization, and it is also possible to prevent decomposition or loss of the resin during the solvent removal process.

[0031] Preferably, the weight ratio of poly(3-hydroxypropionate) and glycolide monomer in step 2 is 1:99 to 99:1. More preferably, the weight ratio of poly(3-hydroxypropionate) and glycolide monomer in step 2 is 1:50 to 50:1, 1:20 to 20:1, 1:10 to 10:1, or 1:1 to 1:10.

[0032] Meanwhile, since the preparation method involves a glycolide ring-opening polymerization reaction, it is carried out in the presence of a glycolide ring-opening catalyst. Preferably, Step 2 is carried out in the presence of a catalyst represented by the following Chemical Formula 4:

[0033] [Chemical formula 4] MA 1 p A 2 2-p In the above Chemical Formula 4, 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.

[0034] More preferably, the catalyst represented by Chemical Formula 4 is tin(II) 2-ethylhexanoate (Sn(Oct)2).

[0035] Preferably, the production method is carried out at 150 to 200° C. Preferably, the production method is carried out for 5 minutes to 10 hours, more preferably 10 minutes to 1 hour.

[0036] The present invention can also provide a resin containing the above-mentioned block copolymer.

[0037] 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.

[0038] The resin composition may be molded into one or more molded articles selected from the group consisting of injection molded articles, extrusion molded articles, inflation molded articles, fibers, nonwoven fabrics, foams, films, and sheets.

[0039] The present invention also provides an article comprising the block copolymer, 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.

[0040] Furthermore, the resin, resin composition, and article containing the block copolymer may further contain an additional comonomer depending on the desired physical properties. [Effects of the Invention]

[0041] As described above, the block copolymer according to the present invention has excellent biodegradability and can expand its range of applications by adjusting its mechanical properties while maintaining the inherent properties of polyglycolic acid. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a graph showing the results of NMR analysis of the block copolymer of Example 1. [Figure 2] 1 is a graph showing the results of NMR analysis of poly(3-hydroxypropionate) of Comparative Example 1. [Figure 3] 1 is a graph showing the results of NMR analysis of the polyglycolic acid of Comparative Example 2. [Figure 4] 1 is a graph showing the results of gel chromatography measurement of the block copolymer of Example 1. [Figure 5] 1 is a graph showing the results of gel chromatography measurement of the block copolymer of Example 2. [Figure 6] 1 is a graph showing the results of measuring the biodegradability of the block copolymer of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0043] Hereinafter, the present invention will be described in more detail with reference to 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. [Example]

[0044] Example 1 Production Example 1-1: Production of poly(3-hydroxypropionate) 7 g (77.71 mmol) of 3-hydroxypropionate was dried and then subjected to polycondensation in the presence of p-toluenesulfonic acid (p-TSA) catalyst at 130°C for 24 hours to produce poly(3-hydroxypropionate).

[0045] The weight-average molecular weight of the produced poly(3-hydroxypropionate) was 2,430.

[0046] Production Example 1-2: Production of block copolymer 25 g of glycolide, 5 g of poly(3-hydroxypropionate) prepared in Preparation Example 1-1, and 0.01 g of tin(II) 2-ethylhexanoate were placed in a 500 mL Teflon-coated round-bottom flask, and the mixture was vacuum-dried at room temperature for 4 hours under a sufficient vacuum.

[0047] The flask was then placed in a preheated oil bath at 130°C, and the temperature was raised to 220°C, followed by ring-opening polymerization for 30 minutes. After the reaction was completed, residual monomers were removed through a devolatilization step to obtain the final block copolymer.

[0048] Example 2 A block copolymer was produced in the same manner as in Example 1, except that 15 g of glycolide and 10 g of poly(3-hydroxypropionate) were used in Production Example 1-2 of Example 1.

[0049] Comparative Example 1: Preparation of poly(3-hydroxypropionate) 7 g (77.71 mmol) of 3-hydroxypropionate was dried and then subjected to polycondensation in the presence of p-toluenesulfonic acid (p-TSA) catalyst at 130°C for 24 hours to produce poly(3-hydroxypropionate).

[0050] Comparative Example 2: Production of polyglycolic acid A 500 mL Teflon-coated round-bottom flask was charged with 25 g of glycolide, 20 mg of octanol, and 0.01 g of tin(II) 2-ethylhexanoate, and the mixture was vacuum-dried at room temperature for 4 hours under sufficient vacuum.

[0051] The flask was then placed in an oil bath preheated to 130°C, and the temperature was raised to 220°C, followed by ring-opening polymerization for 30 minutes. After the reaction was completed, residual monomers were removed through a devolatilization step to obtain the final homocopolymer.

[0052] evaluation (1)NMR (Nuclear Magnetic Resonance) analysis NMR analysis was performed at room temperature using a Varian Unity Innovate (500 MHz) NMR spectrometer with a triple-resonance 5 mm probe. The block copolymers or polymers of the examples and comparative examples were diluted to a concentration of approximately 10 mg / ml in solvent, and chemical shifts were expressed in ppm. The solvents used in the NMR measurements of the examples and comparative examples are as follows:

[0053] Example 1: 3:1 mixed solvent of CDCl3 and HFIP (hexafluoroisopropanol) Comparative Example 1: CDCl3 Comparative Example 2: 3:1 mixed solvent of CDCl3 and HFIP (hexafluoroisopropanol)

[0054] FIG. 1 is a graph showing the NMR analysis results of the block copolymer prepared in Example 1, FIG. 2 is a graph showing the NMR analysis results of poly(3-hydroxypropionate) prepared in Comparative Example 1, and FIG. 3 is the NMR analysis results of polyglycolic acid prepared in Comparative Example 2.

[0055] 1 to 3, it was confirmed that the NMR analysis graph of the block copolymer of Example 1 showed a peak due to the 3HP-derived repeating unit and a peak due to the glycolide-derived repeating unit.

[0056] (2) GPC (Gel Permeation Chromatography) analysis

[0057] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the block copolymers prepared in Examples 1 and 2 were measured using gel permeation chromatography (GPC, Waters E2640), and the results are shown in Figures 4 and 5.

[0058] Specifically, each block copolymer prepared in Example 1 was dissolved in hexafluoroisopropanol (HFIP) to a concentration of 2 mg / mL, and 20 μL of the solution was injected into the GPC. HFIP was used as the mobile phase for GPC, and the flow rate was 1.0 mL / min. Analysis was performed at 40°C. Two Agilent Mixed-B columns were connected in series. A refractive index detector (RI detector) was used as the detector. The Mw value was derived using a calibration curve generated using polystyrene standard specimens. Nine weight-average molecular weights of polystyrene standard specimens were used: 2,000 g / mol, 10,000 g / mol, 30,000 g / mol, 70,000 g / mol, 200,000 g / mol, 700,000 g / mol, 2,000,000 g / mol, 4,000,000 g / mol, and 10,000,000 g / mol.

[0059] (3) Physical property evaluation The tensile strength, Young's modulus, and tensile elongation of the polymers produced in Example 1 and Comparative Example 2 were measured.

[0060] Specifically, the test was carried out according to ASTM D638, and an ASTM D536 V Type specimen was prepared at 190-200°C using a hot-press machine (Limotem QM900S), and then measured using a UTM (Universal Testing Machine) at 10 mm / s and a load of 60 kg / f.

[0061] [Table 1]

[0062] According to Table 1, the polyglycolic acid of Comparative Example 2 was degraded during specimen preparation, and was broken due to its high crystallinity and low elongation, making it impossible to prepare specimens, and it was difficult to measure its physical properties through thermal processing.

[0063] On the other hand, it was confirmed that the block copolymer of Example 1 had sufficient elongation and that its physical properties could be measured through thermoforming and processing, demonstrating improved physical properties and processability compared to existing polyglycolic acid.

[0064] (4) Measurement of biodegradability The results of measuring the biodegradability of the standard substance cellulose and the block copolymer of Example 1 under home composting conditions of EN17427 are shown in FIG.

[0065] Specifically, the measurements were performed under home composting conditions (28°C, aerobic composting conditions, compost moisture content was set at 50%, compost was mixed with the polymer to be measured at a weight ratio of 10:1, and the CO2 generated was measured). Degradation (%) refers to the calculated mass of the sample decomposed into water and CO2 based on the initial mass. For comparison, the biodegradation measurement results for the standard material cellulose (Sigma Aldrich, Cellulose, Cat. No. 310697) are also shown.

[0066] Measurement of the biodegradability of the block copolymer of Example 1 showed that it was degraded by more than 40% within 40 days, while cellulose was degraded by approximately 60% in the same time, demonstrating that the biodegradability of Example 1 increases over time compared to the biodegradability of cellulose. This confirms that the block copolymer of Example 1 has biodegradability even under relatively mild home composting conditions.

Claims

1. A block copolymer represented by the following chemical formula 1: 【Chemistry 1】 In the above Chemical Formula 1, R １ , and R ２ are each independently hydrogen, N, O, S, or substituted or unsubstituted C １－２０ is alkyl, X １ , and X ２ each independently represents a direct bond, —COO—, —NR′CO—, —(NR′)(COO)—, —R′NCONR′—, or —OCOO—; R' is independently hydrogen or C １－２０ is alkyl, L is a direct bond; １－１０ Alkylene; substituted or unsubstituted C ６－６０ arylene; or C containing one or more heteroatoms selected from the group consisting of substituted or unsubstituted N, O, and S ２－６０ is heteroarylene, n and m are each independently an integer of 10 to 700, and m is an integer of 10 to 700.

2. X １ , X ２ 10. The block copolymer of claim 1, wherein L is a direct bond.

3. The block copolymer according to claim 1, wherein the chemical formula 1 is represented by the following chemical formula 1-1: 【Chemistry 2】 In the formula 1-1, n and m are as defined in claim 1.

4. The weight average molecular weight of the block copolymer is 10,000 g / mol to 500,000 g / mol. The block copolymer of claim 1 .

5. Producing poly(3-hydroxypropionate) (Step 1); Step 2: ring-opening polymerizing glycolide monomer in the presence of a poly(3-hydroxypropionate) initiator to produce a block copolymer; The weight ratio of poly(3-hydroxypropionate) and glycolide monomer in step 2 is 1:99 to 99:1; Method for producing block copolymers.

6. The poly(3-hydroxypropionate) of step 1 has a weight average molecular weight of 1,000 g / mol to 500,000 g / mol. A method for producing the block copolymer according to claim 5 .

7. Step 2 is carried out in the presence of a catalyst represented by the following formula 4: A method for producing the block copolymer according to claim 5: [Chemical formula 4] MA １ ｐ A ２ ２－ｐ In the above Chemical Formula 4, 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.

8. The method for producing a block copolymer according to claim 5, wherein the catalyst is tin(II) 2-ethylhexanoate.

9. A resin comprising the block copolymer according to any one of claims 1 to 4.

10. A resin composition comprising the resin according to claim 9.

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

12. An article comprising the block copolymer of claims 1 to 4.

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