Blended resin composition and blended film comprising same

Abstract

The present invention provides a blend resin composition and a blend film comprising the same, the blend resin composition comprising a continuous phase containing polylactic acid, a dispersed phase containing poly (3-hydroxypropionate), and two or more different compatibilizers, and satisfying a predetermined complex viscosity ratio and storage modulus ratio.

Description

[0001] Cross-reference to related applications

[0002] This application claims the priority and benefits of Korean Patent Application No. 10-2023-0098841, filed with the Korean Intellectual Property Office on July 28, 2023, and Korean Patent Application No. 10-2024-0087702, filed with the Korean Intellectual Property Office on July 3, 2024. The entire disclosure of these patent applications is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a blend resin composition and a blend film comprising the blend resin composition. Background Art

[0004] Typical general-purpose plastic films currently widely used include polyvinyl chloride (PVC), polyethylene (PE), or polypropylene (PP) derived from petroleum. Recently, there has been research on applying polyester resins, which are highly biodegradable by themselves, to film products. However, their application in packaging films is limited due to insufficient mechanical strength, flexibility, heat resistance, impact resistance, and transparency.

[0005] Poly(3-hydroxypropionate) (hereinafter referred to as P3HP) is a flexible and biodegradable polyester material, but it has poor mechanical strength and flexibility, so it is difficult to be used as a single polymer. In addition, polylactic acid (PLA) is known to be biodegradable and has excellent mechanical properties such as tensile strength and elastic modulus, but its elongation characteristics are poor, and it exhibits a brittle nature (brittleness), which limits its use as a general-purpose resin. Therefore, there is currently research on blending polylactic acid with poly(3-hydroxypropionate) to complement the two materials, but its physical properties still have limitations.

[0006] For example, when polylactic acid and poly(3-hydroxypropionate) are simply blended and applied to film products, the compatibility between the two materials is low, so the transparency of the film will be significantly reduced, making it difficult to use for packaging applications that require transparency. In addition, due to the low interfacial adhesion between the two materials, mechanical properties such as tensile strength and impact resistance will be reduced, making it difficult to replace traditional general-purpose plastic films. Summary of the Invention

[0007] Technical problem

[0008] An object of the present invention is to provide a biodegradable blend resin composition and a blend film comprising the blend resin composition, the blend resin composition having excellent mechanical properties (such as tensile strength and elongation), optical properties (such as transmittance), and moisture and air barrier properties.

[0009] Technical solution

[0010] According to an embodiment of the present invention, there is provided a blend resin composition, which includes: a continuous phase containing polylactic acid, a dispersed phase containing poly(3-hydroxypropionate), and two or more different compatibilizers, wherein the complex viscosity ratio according to the following formula 1 is 0.40 or less, and the storage modulus ratio according to the following formula 2 is 0.30 or less.

[0011] [Formula 1]

[0012] Complex viscosity ratio = complex viscosity of the dispersed phase / complex viscosity of the continuous phase

[0013] [Formula 2]

[0014] Storage modulus ratio = storage modulus of the dispersed phase / storage modulus of the continuous phase

[0015] In Formula 1 and Formula 2, the storage modulus and the complex viscosity are values measured at a temperature of 180 °C.

[0016] According to another embodiment of the present disclosure, there is provided a blend resin film containing the blend resin composition.

[0017] Now, the blend resin composition according to the specific embodiments of the present disclosure and the blend film containing the blend resin composition will be described in more detail.

[0018] Unless specifically mentioned herein, the term "comprising" or "including" means including certain elements (or components) without any limitation and should not be construed as excluding the addition of other elements (or components).

[0019] In addition, unless otherwise specified herein, the weight-average molecular weight of polymers and copolymers can be measured using gel permeation chromatography (GPC). Specifically, the polymers and copolymers are dissolved in chloroform at a concentration of 2 mg / ml, and then 20 μl of this solution is injected into the GPC, and GPC analysis is performed at 40 °C. At this time, chloroform is used as the mobile phase of the GPC, the flow rate is 1.0 mL / min, and the chromatographic columns used are two Agilent Mixed-B units in series. An RI detector is used as the detector. The value of Mw can be obtained using a calibration curve formed by polystyrene standard samples. Nine polystyrene standard samples are used, and the weight-average molecular weights are 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, respectively.

[0020] As used herein, "substituted or unsubstituted" means unsubstituted or substituted with one or more substituents selected from deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amino group, a phosphine oxide group, an alkoxy group, an aryloxy group, an alkylsulfoxy group, an arylsulfoxy group, an alkylsulfinyl group; an arylsulfinyl group; a silicon group; a boron group; an alkyl group; a cycloalkyl group; an alkenyl group; an aryl group; an aralkyl group; an aralkenyl group; an alkylaryl group; an alkylamino group; an aralkylamino group; a heteroarylamino group; an arylamino group; an arylphosphine group; and a heterocyclic group containing at least one of N, O, and S atoms, or unsubstituted or substituted with a substituent formed by linking two or more of the above-listed substituents. For example, "a substituent formed by linking two or more substituents" may be a biphenyl group. That is, a biphenyl group may be an aryl group, or may be understood as a substituent formed by linking two phenyl groups.

[0021] In the past, when poly(lactic acid) and poly(3-hydroxypropionate) were simply mixed and applied to film products, there were problems in that the compatibility between the two materials was low, so the transparency of the film was significantly reduced, making it difficult to use for packaging applications that require transparency, and the interfacial adhesion between the two materials was low, so mechanical properties such as tensile properties and impact resistance were reduced.

[0022] Therefore, the present inventors found that when the blend resin composition includes a continuous phase containing poly(lactic acid), a dispersed phase containing poly(3-hydroxypropionate), and two or more different compatibilizers, and the complex viscosity ratio according to Formula 1 is 0.40 or less and the storage modulus ratio according to Formula 2 is 0.30 or less, its mechanical properties such as tensile strength and elongation, optical properties such as transmittance, and moisture and air barrier properties are excellent, thus completing the present invention.

[0023] In addition, since poly(lactic acid) and poly(3-hydroxypropionate) exhibit environmentally friendly and biodegradable characteristics while containing a large amount of bio-based raw materials, a film containing the poly(lactic acid) and poly(3-hydroxypropionate) can also contain a large amount of bio-based raw materials while maintaining the environmentally friendly and biodegradable characteristics.

[0024] According to an embodiment of the present disclosure, there is provided a blend resin composition including: a continuous phase containing poly(lactic acid), a dispersed phase containing poly(3-hydroxypropionate), and two or more different compatibilizers, wherein the complex viscosity ratio according to Formula 1 is 0.40 or less, and the storage modulus ratio according to Formula 2 is 0.30 or less.

[0025] Specifically, the complex viscosity ratio of the blend resin composition according to Formula 1 may be 0.40 or less, 0.01 or more and 0.30 or less, 0.02 or more and 0.20 or less, or 0.02 or more and 0.15 or less. In addition, the storage modulus ratio of the blend resin composition according to Formula 2 may be 0.300 or less, 0.001 or more and 0.200 or less, 0.002 or more and 0.100 or less, 0.003 or more and 0.090 or less, or 0.004 or more and 0.080 or less. When the complex viscosity ratio and / or the storage modulus ratio of the blend resin composition is too high, the elongation at break or the light transmittance may decrease.

[0026] The blend resin composition uses a combination of two or more compatibilizers having different affinities for polylactic acid and poly(3-hydroxypropionate), or controls the molecular weight of poly(3-hydroxypropionate) and the linear or branched structure of poly(3-hydroxypropionate), so that the complex viscosity ratio and the storage modulus ratio can meet the above ranges. In addition, since the complex viscosity ratio and the storage modulus ratio meet the above ranges, the dispersed phase morphology in the blend resin composition may have a layered structure, and thus excellent mechanical properties such as tensile strength and elongation at break, optical properties such as transmittance, and moisture and air barrier properties are exhibited.

[0027] Specifically, Figure 3 FIG. is a schematic diagram of the deformation process of the dispersed phase morphology during the film formation process using the blend resin composition. Referring to this, the flow properties of the composition in the die region and the die exit region are important factors determining the dispersed phase morphology and quality in the film. In the die region, the dispersed phase is deformed and broken due to strong shear stress, while in the die exit region, stress relaxation phenomena depending on the viscoelastic properties of the blend resin composition may occur. For example, when a blend resin composition with very high viscoelasticity is used as a raw material, the dispersed phase is difficult to deform and break inside the extruder, or the dispersed phase deformed into a layered shape in the extruder can quickly recover its elasticity at the die exit. Therefore, it may be difficult to finally produce a film with a layered dispersed phase structure having a high aspect ratio.

[0028] However, in the blend resin composition according to one embodiment, the complex viscosity ratio and the storage modulus ratio satisfy the above ranges. Therefore, the deformation and fragmentation of the dispersed phase are easily carried out in the extruder, and the deformation is maintained at the discharge port, so that a layered dispersed phase structure having a high aspect ratio can be included. The blend resin composition and the blend film containing such a layered dispersed phase structure having a high aspect ratio exhibit excellent mechanical properties (such as tensile strength and elongation), optical properties (such as transmittance), and moisture and air barrier properties. Specifically, the dispersed phase may have an average aspect ratio of 6.0 or more, 7.0 or more and 20.0 or less, 8.0 or more and 18.0 or less, or 9.0 or more and 16.0 or less. If the average aspect ratio of the dispersed phase is too small, that is, a layered dispersed phase structure is not presented, the elongation or light transmittance of the blend resin composition and the blend film containing the dispersed phase may be reduced.

[0029] In the complex viscosity ratio, the complex viscosity of the dispersed phase can be obtained by measuring the complex viscosity of poly(3-hydroxypropionate) contained in the dispersed phase of the blend resin composition, and the complex viscosity of the continuous phase can be obtained by measuring the complex viscosity of polylactic acid contained in the continuous phase of the blend resin composition.

[0030] Similarly, in the storage modulus ratio, the storage modulus of the dispersed phase can be obtained by measuring the storage modulus of poly(3-hydroxypropionate) contained in the dispersed phase of the blend resin composition, and the storage modulus of the continuous phase can be obtained by measuring the storage modulus of polylactic acid contained in the continuous phase of the blend resin composition.

[0031] The complex viscosity and the storage modulus can be measured using a viscoelasticity measuring device under the conditions of an angular frequency of 0.3 rad / s to 500 rad / s, a dynamic strain frequency scanning mode, a measurement temperature of 180 °C, and a strain of 0.5%.

[0032] Based on 500 rad / s, the complex viscosity of the dispersed phase can be 0.5 Pa·s or more and 500 Pa·s or less, 1.0 Pa·s or more and 450 Pa·s or less, 1.5 Pa·s or more and 400 Pa·s or less, or 2.0 Pa·s or more and 350 Pa·s or less. Based on 500 rad / s, the complex viscosity of the continuous phase can be 500 Pa·s or more and 100,000 Pa·s or less, 550 Pa·s or more and 90,000 Pa·s or less, 600 Pa·s or more and 85,000 Pa·s or less, or 650 Pa·s or more and 80,000 Pa·s or less.

[0033] Based on 500 rad / s, the storage modulus of the dispersed phase can be 20 Pa·s or more and 50,000 Pa·s or less, 30 Pa·s or more and 45,000 Pa·s or less, 40 Pa·s or more and 40,000 Pa·s or less, or 50 Pa·s or more and 35,000 Pa·s or less.

[0034] Based on 500 rad / s, the storage modulus of the continuous phase can be 50,000 Pa·s or more and 5,000,000 Pa·s or less, 45,000 Pa·s or more and 4,500,000 Pa·s or less, 40,000 Pa·s or more and 4,000,000 Pa·s or less, or 35,000 Pa·s or more and 3,500,000 Pa·s or less.

[0035] Based on 500 rad / s, the complex viscosity of the blend resin composition can be 550 Pa·s or more and 900 Pa·s or less, 560 Pa·s or more and 850 Pa·s or less, 570 Pa·s or more and 830 Pa·s or less, or 580 Pa·s or more and 800 Pa·s or less.

[0036] Based on 500 rad / s, the storage modulus of the blend resin composition can be 10,000 Pa·s or more and 2,000,000 Pa·s or less, 20,000 Pa·s or more and 1,500,000 Pa·s or less, or 30,000 Pa·s or more and 1,000,000 Pa·s or less.

[0037] The blend resin composition according to one embodiment may include two or more different compatibilizers. The compatibilizer can react with the end groups of polylactic acid and poly(3-hydroxypropionate), namely, hydroxyl group (-OH) and carboxyl group (-COOH), to carry out a coupling reaction, thereby improving the compatibility of the blend resin composition.

[0038] In addition, two or more different compatibilizers may have different affinities for, for example, polylactic acid and poly(3-hydroxypropionate). For example, two or more compatibilizers may include a first compatibilizer having an interfacial tension difference with polylactic acid of 0.3 mN / m or more and 2.0 mN / m or less at 180 °C, and a second compatibilizer having an interfacial tension difference with polylactic acid of 2.0 mN / m or more and 8.0 mN / m or less at 180 °C. Since the blend resin composition contains the first compatibilizer and the second compatibilizer having different interfacial tension differences at 180 °C, the complex viscosity ratio and the storage modulus ratio satisfy the above ranges, and the average aspect ratio of the dispersed phase satisfies the above range. Therefore, mechanical properties such as tensile strength and elongation, optical properties such as transmittance, and moisture and air barrier properties can be excellent.

[0039] The interfacial tension difference between the first compatibilizer and polylactic acid at 180°C can be 0.3 mN / m or more and 2.0 mN / m or less, 0.5 mN / m or more and 1.8 mN / m or less, 0.7 mN / m or more and 1.6 mN / m or less, or 0.8 mN / m or more and 1.4 mN / m or less. The interfacial tension difference between the second compatibilizer and polylactic acid at 180°C can be more than 2.0 mN / m and 8.0 mN / m or less, 2.5 mN / m or more and 7.5 mN / m or less, 3.0 mN / m or more and 7.0 mN / m or less, 3.5 mN / m or more and 6.5 mN / m or less, or 4.0 mN / m or more and 5.5 mN / m or less.

[0040] The affinity of the first compatibilizer for polylactic acid can be higher than its affinity for poly(3-hydroxypropionate). In addition, the affinity of the second compatibilizer for poly(3-hydroxypropionate) can be higher than its affinity for polylactic acid. Further, the affinity of the first compatibilizer for polylactic acid can be higher than that of the second compatibilizer, and the affinity of the second compatibilizer for poly(3-hydroxypropionate) can be higher than that of the first compatibilizer.

[0041] Due to the high affinity of the first compatibilizer for polylactic acid, when kneading the composition in an extruder, the first compatibilizer can easily move into the continuous phase containing polylactic acid, thereby significantly increasing the relative concentration of the first compatibilizer in the continuous phase. Therefore, when only the first compatibilizer is used, the first compatibilizer may be used for the chain extension reaction between "polylactic acid and polylactic acid" or "poly(3-hydroxypropionate) and poly(3-hydroxypropionate)", rather than the coupling reaction between polylactic acid and poly(3-hydroxypropionate) at the interface between the dispersed phase and the continuous phase. In this case, the compatibility and mechanical properties of the blend resin composition and the film will be reduced. However, since the blend resin composition according to one embodiment includes both the first compatibilizer and the second compatibilizer, the compatibility, mechanical properties, and optical properties of the blend resin composition and the film can all be excellent.

[0042] The first compatibilizer can be an acrylate copolymer having three or more epoxy groups. For example, the acrylate copolymer can have 3 or more and 30 or less, 4 or more and 25 or less, or 5 or more and 20 or less epoxy groups, and its epoxy equivalent can be 200 g / mol or more and 600 g / mol or less, 250 g / mol or more and 550 g / mol or less, 300 g / mol or more and 500 g / mol or less, or 350 g / mol or more and 450 g / mol or less.

[0043] In addition, the weight-average molecular weight of the acrylate copolymer having three or more epoxy groups may be 1,000 or more and 15,000 or less, 2,000 or more and 13,000 or less, 3,000 or more and 11,000 or less, or 5,000 or more and 10,000 or less.

[0044] In addition, the acrylate copolymer having three or more epoxy groups may be a copolymer obtained by polymerizing two or more monomers selected from styrene, glycidyl (meth)acrylate, butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, (meth)acrylic acid, itaconic acid, maleic anhydride, acrylamide, and 2-ethylhexyl (meth)acrylate.

[0045] In addition, the first compatibilizer may include a repeating unit represented by the following Chemical Formula 1.

[0046] [Chemical Formula 1]

[0047]

[0048] In Chemical Formula 1,

[0049] R1 to R6 may each independently be hydrogen, deuterium, a hydroxyl group, a nitro group, an amino group, a substituted or unsubstituted alkyl group having 2 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 2 to 60 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 60 carbon atoms, a substituted or unsubstituted cycloalkyl group having 4 to 60 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms and containing at least one of O, N, Si, and S.

[0050] For example, R1 to R3 may each independently be hydrogen or deuterium.

[0051] In addition, R4 and R6 may each independently be hydrogen, deuterium, methyl, ethyl, or propyl.

[0052] In addition, R5 may be an alkyl group having 2 to 60 carbon atoms.

[0053] x, y, and z may each independently be an integer of 1 to 20.

[0054] The second compatibilizer contained in the blend resin composition according to one embodiment may be a compound based on a difunctional glycidyl ether, a compound based on a trifunctional glycidyl ether, or a mixture thereof.

[0055] The compound based on difunctional glycidyl ether can be a compound having glycidyl groups at both ends, and its number average molecular weight can be 100 to 15,000, 200 to 10,000, 300 to 9,000 or 500 to 8,000.

[0056] The compound based on difunctional glycidyl ether can be a compound represented by the following Chemical Formula 2.

[0057] [Chemical Formula 2]

[0058]

[0059] Wherein, in Chemical Formula 2,

[0060] X is a substituted or unsubstituted alkylene group having 2 to 60 carbon atoms, or a substituted or unsubstituted arylene group having 6 to 60 carbon atoms,

[0061] and n can be an integer from 1 to 20.

[0062] The compound based on difunctional glycidyl ether can include but is not limited to, for example, at least one selected from polyethylene glycol diglycidyl ether (PEG-DE), polypropylene glycol diglycidyl ether (PPG-DE), ethylene glycol diglycidyl ether (EG-DE), neopentyl glycol diglycidyl ether (NG-DE), glycerol diglycidyl ether (Gly-DE) and resorcinol diglycidyl ether (RSN-DE).

[0063] The compound based on trifunctional glycidyl ether can be a compound containing three glycidyl groups, and its number average molecular weight can be 100 to 15,000, 150 to 10,000, 200 to 9,000 or 300 to 8,000.

[0064] The compound based on trifunctional glycidyl ether can be a compound represented by the following Chemical Formula 3.

[0065] [Chemical Formula 3]

[0066]

[0067] Wherein, in Chemical Formula 3,

[0068] Y1 to Y3 are each independently a substituted or unsubstituted alkylene group having 2 to 60 carbon atoms, or a substituted or unsubstituted arylene group having 6 to 60 carbon atoms,

[0069] R7 can be hydrogen, deuterium, methyl, ethyl or propyl.

[0070] The compounds based on trifunctional glycidyl ethers may include, but are not limited to, for example, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, tris(4-hydroxyphenyl)methane triglycidyl ether, etc.

[0071] Based on 100% by weight of the blended resin composition, the content of the two or more different compatibilizers may be 0.1% by weight or more and 10.0% by weight or less, 0.2% by weight or more and 9.0% by weight or less, 0.3% by weight or more and 8.0% by weight or less, or 0.4% by weight or more and 7.0% by weight or less. If the content of the compatibilizer is too small, the compatibility improvement effect cannot be exerted. If the content of the compatibilizer is too large, the material of the composition or the film becomes too hard, which may make it difficult to be used for applications such as packaging films.

[0072] In addition, the weight ratio between the first compatibilizer and the second compatibilizer may be 10:90 to 60:40, 20:80 to 55:45, or 30:70 to 50:50. If the first compatibilizer and the second compatibilizer do not satisfy the above weight ratio, the compatibility improvement effect cannot be exerted.

[0073] The blended resin composition according to one embodiment includes a continuous phase containing polylactic acid and a dispersed phase containing poly(3-hydroxypropionate).

[0074] The above-mentioned polylactic acid is a polymer with lactic acid or lactide as a monomer, and has excellent physical properties such as biodegradability and high rigidity, and may be at least one of poly-L-lactic acid, poly-D-lactic acid, and poly-L,D-lactic acid. The weight-average molecular weight of the polylactic acid may be 100,000 or more and 400,000 or less, 130,000 or more and 350,000 or less, 150,000 or more and 330,000 or less, 180,000 or more and 300,000 or less, or 200,000 or more and 250,000 or less. If the weight-average molecular weight of the polylactic acid is too low, the mechanical strength of the blended resin composition containing the polylactic acid and the film prepared from the composition may be reduced. If the weight-average molecular weight of the polylactic acid is too high, the extrusion processing may be difficult.

[0075] Poly(3-hydroxypropionate) may be a polymer produced by microbial culture, or a polymer prepared by polymerizing 3-hydroxypropionate produced by microbial culture.

[0076] The weight-average molecular weight of poly(3-hydroxypropionate) can be 10,000 or more and 350,000 or less, 13,000 or more and 300,000 or less, 15,000 or more and 250,000 or less, 18,000 or more and 230,000 or less, or 20,000 or more and 200,000 or less. If the weight-average molecular weight of poly(3-hydroxypropionate) is too low, the effect of improving the flexibility of polylactic acid may be reduced. If the weight-average molecular weight of poly(3-hydroxypropionate) is too high, the miscibility of the blend resin composition containing the poly(3-hydroxypropionate) and the film prepared therefrom may be reduced.

[0077] In addition, the polydispersity index (PDI) of poly(3-hydroxypropionate) can be 1.0 or more and 13.0 or less, 1.5 or more and 11.0 or less, 2.0 or more and 9.0 or less, 2.5 or more and 8.0 or less, or 3.0 or more and 7.0 or less.

[0078] According to one embodiment, the weight ratio between polylactic acid and poly(3-hydroxypropionate) contained in the blend resin composition can be 99:1 to 60:40, 98:2 to 70:30, 97:3 to 80:20, 96:4 to 85:25, 95:5 to 90:10. When the amount of poly(3-hydroxypropionate) is too large relative to polylactic acid, the miscibility of the blend resin composition and the film prepared therefrom may be reduced. When the amount of poly(3-hydroxypropionate) is too small relative to polylactic acid, the effect of improving the flexibility of polylactic acid may be reduced.

[0079] The blend resin composition may further include an antioxidant. Based on 100% by weight of the blend resin composition, the content of the antioxidant can be 0.001 to 1% by weight. Preferably, the content of the antioxidant can be 0.01 to 0.1% by weight.

[0080] The antioxidant can be at least one selected from phenol-based antioxidants, amine-based antioxidants, thio-based antioxidants, and phosphine-based antioxidants, but is not limited thereto.

[0081] Specific examples of antioxidants may include phosphoric acid-based heat stabilizers such as phosphoric acid, trimethyl phosphate, or triethyl phosphate; hindered phenol-based primary antioxidants such as 2,6-di-tert-butyl-p-cresol, octadecyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, tetra[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, diethyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphite, 2,2'-thiobis(4-methyl-6-tert-butylphenol), 2,6-g,t-butylphenol, 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), or ethylene glycol bis[3,3-bis-(4'-hydroxy-3'-tert-butylphenyl)butyrate]; amine-based secondary antioxidants such as phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, or N,N'-di-β-naphthyl-p-phenylenediamine; sulfur-based secondary antioxidants such as dilauryl disulfide, dilauryl thiodipropionate, distearyl thiodipropionate, mercaptobenzothiazole, or tetramethylthiuram disulfide, tetra[methylene-3-(dodecylthio)propionate]methane; or phosphite-based secondary antioxidants such as triphenyl phosphite, tris(nonylphenyl) phosphite, triisodecyl phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, or tetrakis[2,4-bis(1,1-dimethylethyl)phenyl] (1,1'-biphenyl)-4,4'-diylbisphosphonate.

[0082] The blend resin composition can be prepared by kneading using an extruder in a certain extrusion process. Specifically, polylactic acid and poly(3-hydroxypropionate) can be mixed in the form of granules and powders of similar size in the main hopper and then loaded. In addition, two or more compatibilizers can also be loaded into the main hopper. The extrusion kneading step of the blend resin can be carried out at a temperature of 150 to 200 °C, 160 to 190 °C, or 170 to 185 °C for 30 minutes to 1 hour. Additionally, if the extrusion conditions are below the above range, the resin viscosity increases, the fluidity decreases, resulting in problems such as an increase in extrusion torque, while if the extrusion conditions exceed the above range, there are problems such as polymer discoloration and a decrease in physical properties.

[0083] The extruder can be a water-cooled twin-screw extruder. Additionally, the extrusion conditions of the twin-screw extruder are preferably that the extrusion screw rotation speed is 100 to 200 rpm and the pelletizer rotation speed is 100 to 500 rpm. The extruder can be a co-rotating twin-screw extruder, and the screw rotation speed in the extruder and the pelletizer rotation speed can be adjusted within the above ranges to facilitate the extrusion kneading process.

[0084] The discharging temperature of the final discharging part of the screw of the water-cooled twin-screw extruder is 170 to 220 °C, 180 to 210 °C, 190 to 200 °C, the discharging temperature of the remaining screw part is 150 to 200 °C, 160 to 190 °C, 170 to 185 °C, and the temperature of the main hopper is preferably 120 to 170 °C, 130 to 160 °C, 140 to 150 °C. The final discharging part of the screw may refer to the part equivalent to 1 / 20 of the total length of the entire screw of the water-cooled twin-screw extruder. In the water-cooled twin-screw extruder, if the temperature of the final discharging part of the screw is too low, there is a problem that the resin cannot be smoothly discharged due to insufficient fluidity, and if the temperature is too high, there are problems of poor physical properties and discoloration of the polymer.

[0085] According to another embodiment of the present invention, there is provided a blended film containing the blended resin composition.

[0086] Measured according to ASTM D882, the tensile strength of the blended film can be 40 MPa or more, 45 MPa or more, or 50 to 200 MPa.

[0087] In addition, measured according to ASTM D882, the elongation at break of the blended film can be 100% or more, 200% or more, 250% or more, 300% or more, and 500% or less.

[0088] In addition, the light transmittance of the blended film can be 80% or more, 82% or more, 84% or more, 85% or more, and 100% or less.

[0089] The thickness of the blended film can be 10 to 300 μm, more specifically, it can be 10 μm or more, 20 μm or more, 30 μm or more, or 300 μm or less, 200 μm or less, or 150 μm or less. Since the thickness of the film is within the above range, it has strong elasticity, excellent operability, and improved winding state or unwinding property. If the film thickness is too thin, the tensile strength, tear strength, and elongation at break will deteriorate, and the film may be punctured or torn during use. If the film thickness is too thick, the unit price competitiveness may be reduced. The blended film can be used as medical individual packaging, food packaging, garbage bags, agricultural mulch films, disposable gloves, or packaging bags for various industrial products.

[0090] The manufacturing method of the blended film is not particularly limited, but a blended resin composition can be used to obtain the blended film according to conventional film manufacturing methods such as the blown film method, tubular method, T-die casting method, etc. For example, the composition can be made into pellets, and the pellets can be dried at 60 to 100 °C for 6 hours or more, and the moisture content can be controlled below 1200 ppm, below 500 ppm, or below 200 ppm.

[0091] Subsequently, the composite material made into particles can be coated on a release film and then placed in a hot press for pressing to form a film. At this time, the temperature can be 130 to 250 °C, 150 to 220 °C, or 160 to 200 °C, and the pressure can be 5 MPa to 20 MPa, 8 MPa to 17 MPa, or 10 MPa to 15 MPa.

[0092] Advantageous effects

[0093] According to the present disclosure, a biodegradable blend resin composition and a blend film containing the blend resin composition can be provided. While maintaining environmental affinity and biodegradability, the blend resin composition has excellent mechanical properties (such as tensile strength and elongation), optical properties (such as transmittance), and moisture and air barrier properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 is a cross-sectional SEM image of the blend film of Example 1.

[0095] Figure 2 is a schematic diagram showing the dispersed phase.

[0096] Figure 3 is a schematic diagram showing the morphological deformation process of the dispersed phase during the formation of a film using the blend resin composition. DETAILED DESCRIPTION

[0097] Hereinafter, embodiments of the present disclosure will be described in detail with reference to examples. However, the following examples are for illustrative purposes only, and the detailed description of the present disclosure is not limited by these examples.

[0098] Preparation Example 1: Preparation of Poly(3-hydroxypropionic acid) A

[0099] 3-Hydroxypropionic acid (3HP) dissolved in water was placed in an RBF and dried for 2 hours at 90 °C and 100 Torr. 300 g of dried 3-hydroxypropionic acid (3HP) was placed in a reactor and reacted at 90 °C for 12 hours using 230 mg of p-TSA (0.2 mol% based on 1 mol of 3HP) as a catalyst to prepare poly(3-hydroxypropionic acid) A (weight average molecular weight: 25,000 g / mol).

[0100] Preparation Example 2: Preparation of Poly(3-hydroxypropionic acid) B

[0101] 3-Hydroxypropionic acid (3HP) dissolved in water was placed in an RBF, and the water was dried at 90 °C and 100 Torr for 2 hours. 300 g of dried 3-hydroxypropionic acid (3HP) was placed in a reactor, and 460 mg of p-TSA (0.4 mol% based on 1 mol of 3HP) was used as a catalyst, and the reaction was carried out at 90 °C for 24 hours to prepare poly(3-hydroxypropionic acid) B (weight-average molecular weight: 150,000 g / mol).

[0102] Preparation Example 3: Preparation of poly(3-hydroxypropionic acid) C

[0103] 3-Hydroxypropionic acid (3HP) dissolved in water was placed in an RBF, and the water was dried at 90 °C and 100 Torr for 2 hours. 300 g of dried 3-hydroxypropionic acid (3HP) was placed in a reactor, and 690 mg of p-TSA (0.6 mol% based on 1 mol of 3HP) was used as a catalyst, and the reaction was carried out at 90 °C for 48 hours to prepare poly(3-hydroxypropionic acid) C (weight-average molecular weight: 400,000 g / mol).

[0104] Example 1

[0105] 90 g of polylactic acid (product name: PLA-2003D, manufacturer: NatureWorks, weight-average molecular weight: 200,000), 10 g of poly(3-hydroxypropionate) A prepared in Preparation Example 1, 0.5 g of a first compatibilizer (product name: Joncryl ADR-4400, manufacturer: BASF), 1.0 g of a second compatibilizer (polyethylene glycol diglycidyl ether, product name: polyethylene glycol diglycidyl ether (Mn 500, manufacturer: Sigma-Aldrich)), 0.25 g of Irganox 1010 and 0.25 g of Irgafos 168 as antioxidants were mixed, and a blend resin composition was prepared using a co-rotating twin-screw extruder. At this time, the reaction was carried out for 5 minutes under the conditions of an extruder barrel temperature of 185 °C and an extrusion speed of 400 rpm to prepare a blend resin composition, which was formed into pellets.

[0106] After extrusion, a blend film was made using the pelletized sample in an extrusion molding machine. When forming the film, the barrel temperature was 185 °C, the die temperature was 160 °C, the roll speed was 200 rpm, and the blend film thickness was 0.2 mm.

[0107] Example 2

[0108] Except that 10 g of poly(3-hydroxypropionate) B prepared in Preparation Example 2 was used instead of 10 g of poly(3-hydroxypropionate) A prepared in Preparation Example 1, a blend resin composition and a blend film were prepared in the same manner as in Example 1.

[0109] Example 3

[0110] Except that 95 g of polylactic acid (product name: PLA-2003D, manufacturer: NatureWorks, weight-average molecular weight: 200,000) is used instead of 90 g of polylactic acid (product name: PLA-2003D, manufacturer: NatureWorks, weight-average molecular weight: 200,000); 5 g of poly(3-hydroxypropionate) A prepared in Preparation Example 1 is used instead of 10 g of poly(3-hydroxypropionate) A prepared in Preparation Example 1; and 0.5 g of a second compatibilizer (polyethylene glycol diglycidyl ether, product name: polyethylene glycol diglycidyl ether (Mn 500, manufacturer: Sigma-Aldrich)) is used instead of 1.0 g of the second compatibilizer (polyethylene glycol diglycidyl ether, product name: polyethylene glycol diglycidyl ether (Mn 500, manufacturer: Sigma-Aldrich)), a blend resin composition and a blend film are prepared in the same manner as in Example 1.

[0111] Example 4

[0112] Except that 0.5 g of a first compatibilizer (product name: Joncryl ADR-4468, manufacturer: BASF) is used instead of 0.5 g of the first compatibilizer (product name: Joncryl ADR-4400, manufacturer: BASF), a blend resin composition and a blend film are prepared in the same manner as in Example 1.

[0113] Example 5

[0114] Except that 1.0 g of trimethylolpropane triglycidyl ether (Mn 302, manufacturer: Sigma-Aldrich) is used as the second compatibilizer instead of 1.0 g of the second compatibilizer (polyethylene glycol diglycidyl ether, product name: polyethylene glycol diglycidyl ether (Mn 500, manufacturer: Sigma-Aldrich)), a blend resin composition and a blend film are prepared in the same manner as in Example 1.

[0115] Comparative Example 1

[0116] Except that 10 g of poly(3-hydroxypropionate) C prepared in Preparation Example 3 is used instead of 10 g of poly(3-hydroxypropionate) A prepared in Preparation Example 1, a blend resin composition and a blend film are prepared in the same manner as in Example 1.

[0117] Comparative Example 2

[0118] Except that the second compatibilizer is not used, a blend resin composition and a blend film are prepared in the same manner as in Example 2.

[0119] [Table 1]

[0120] (Unit: g) PLA P3HP First compatibilizer Second compatibilizer Example 1 90 10 0.5 1.0 Example 2 90 10 0.5 1.0 Example 3 95 5 0.5 0.5 Example 4 90 10 0.5 1.0 Example 5 90 10 0.5 1.0 Comparative Example 1 90 10 0.5 0.5 Comparative Example 2 90 10 0.5 0

[0121] Evaluation

[0122] 1. Measurement of complex viscosity ratio and storage modulus ratio

[0123] The complex viscosity ratio and storage modulus ratio of the blend resin compositions of the examples and comparative examples were measured using a viscoelasticity measuring device (DHR-3; Discovery Hybrid Rheometer, TA Instruments).

[0124] In addition, the measurement conditions for the complex viscosity and storage modulus of the dispersed phase resin, continuous phase resin, and blend resin composition are as follows. Specifically, a parallel plate with a diameter of 25.0 mm was used, the sample was loaded with a gap of 1.0 mm, and the analysis was performed at an angular frequency of 0.3 rad / s to 500 rad / s. In the dynamic strain-free scanning mode, the measurement temperature was 180 °C, the strain was 0.5%, the analysis time was 20 minutes, and the preheating time after sample preparation was controlled to 1.5 minutes.

[0125] [Equation 1]

[0126] Complex viscosity ratio = Complex viscosity of dispersed phase / Complex viscosity of continuous phase

[0127] [Equation 2]

[0128] Storage modulus ratio = Storage modulus of dispersed phase / Storage modulus of continuous phase

[0129] 2. Measurement of average aspect ratio of dispersed phase

[0130] The average aspect ratio of the dispersed phase of the blend resin compositions of the examples and comparative examples was measured using a scanning electron microscope (SEM, JSM 7610F plus, JEOL). The average aspect ratio was calculated by excluding the maximum and minimum aspect ratios of 10 dispersed phases and taking the average of the remaining values.

[0131] In addition, in order to facilitate the observation of the dispersed phase, a fracture surface of the sample was prepared using a cryostat microtome, and then the sample was immersed in a mixed solution of water and methanol for 60 minutes to selectively remove the poly(3-hydroxypropionate) dispersed phase, and the aspect ratio of the dispersed phase was measured.

[0132] Figure 2 It is a schematic diagram of the dispersed phase, where the aspect ratio of the dispersed phase is calculated by substituting the length (A), the major axis length (B) of the cross-section, and the minor axis length (C) of the cross-section of the dispersed phase into the following Equations 3 and 4.

[0133] [Equation 3]

[0134] Aspect ratio of the dispersed phase = Length of the dispersed phase (A) / Diameter of the cross-section of the dispersed phase (Q)

[0135] [Formula 4]

[0136]

[0137] In addition, Figure 1 Fig. Figure 1 is the cross-sectional SEM image of the blend film of Example 1, and it can be seen that the dispersed phase has a layered structure.

[0138] 3. Measurement of Tensile Strength and Elongation at Break

[0139] The tensile strength and elongation at break of the blend films of the examples and comparative examples were measured using a UTM (universal testing machine) according to ASTM D882. The length and width of the samples were controlled according to ASTM D882, and the samples were stabilized at room temperature for at least 48 hours, and the elongation at break was measured at a tensile rate of 40% / min at room temperature. The results are shown in Table 2 below.

[0140] 4. Measurement of Light Transmittance

[0141] The light transmittance of the blend films of the examples and comparative examples was measured using a spectrophotometer with an integrating sphere ["V7100" manufactured by Nihon Bunko Co., Ltd.] in the wavelength range of 380 to 780 nm. The results are shown in Table 2 below.

[0142] [Table 2]

[0143]

[0144] It can be confirmed from Table 1 that in Examples 1 to 5, the complex viscosity ratio is 0.14 or less and the storage modulus ratio is 0.080 or less. Therefore, the average aspect ratio of the dispersed phase is 9 or more, and both the tensile properties and optical properties are excellent. On the other hand, it can be confirmed that in Comparative Example 1, the complex viscosity ratio and the storage modulus ratio are 0.46 and 0.36 respectively. As a result, the viscoelasticity of the dispersed phase is too high, making it difficult for the dispersed phase to deform and break in the extruder, or the elastic recovery of the deformation at the discharging part is fast, so that the average aspect ratio of the dispersed phase is as low as 3. Therefore, both the elongation at break and the permeability are low. In addition, it was also confirmed that in Comparative Example 2, since the second compatibilizer was not used, the coupling reaction efficiency of the compatibilizer at the interface between the dispersed phase and the continuous phase was reduced, resulting in a decrease in the elongation at break.

Claims

1. A blended resin composition comprising: A continuous phase containing polylactic acid, a dispersed phase containing poly(3-hydroxypropionate) and two or more different compatibilizers, wherein the complex viscosity ratio according to the following formula 1 is less than 0.40, and Wherein, the storage modulus ratio according to the following formula 2 is less than 0.

30. [Formula 1] Complex viscosity ratio = complex viscosity of dispersed phase / complex viscosity of continuous phase [Formula 2] Storage modulus ratio = storage modulus of dispersed phase / storage modulus of continuous phase In formulas 1 and 2, The storage modulus and the complex viscosity are values ​​measured at a temperature of 180°C.

2. The blended resin composition according to claim 1, wherein The average aspect ratio of the dispersed phase is 6.0 or more.

3. The blended resin composition according to claim 1, wherein The two or more compatibilizers include: A first compatibilizer having an interfacial tension difference with the polylactic acid of 0.3 mN / m or more and 2.0 mN / m or less at 180° C.; and The second compatibilizer has an interfacial tension difference with the polylactic acid at 180° C. of 2.0 mN / m or more and 8.0 mN / m or less.

4. The blended resin composition according to claim 3, wherein The first compatibilizer is an acrylate-based copolymer having three or more epoxy groups.

5. The blended resin composition according to claim 3, wherein The second compatibilizer is a difunctional glycidyl ether-based compound, a trifunctional glycidyl ether-based compound, or a mixture thereof.

6. The blended resin composition according to claim 1, wherein The content of the two or more different compatibilizers is 0.1 wt % or more and 10 wt % or less based on 100 wt % of the blended resin composition.

7. The blended resin composition according to claim 3, wherein The weight ratio between the first compatibilizer and the second compatibilizer is 10:90 to 60:

40.

8. The blended resin composition according to claim 1, wherein The weight ratio between the polylactic acid and the poly(3-hydroxypropionate) is 99:1 to 60:

40.

9. The blended resin composition according to claim 1, wherein The weight average molecular weight of the polylactic acid is 100,000 or more and 400,000 or less.

10. The blended resin composition according to claim 1, wherein The weight average molecular weight of the poly(3-hydroxypropionate) is 10,000 or more and 350,000 or less. 11 . A blended resin film comprising the blended resin composition according to claim 1 .

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