Resin composition and molded article

Abstract

The present invention relates to a biodegradable resin composition containing different types of biodegradable resins, and relates to a resin composition having excellent processability, in which the compatibility between the different types of biodegradable resins is improved, thereby improving mechanical properties and preventing an increase in the viscosity of the resin composition, and to a biodegradable molded article molded from the resin composition.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0064184, filed May 25, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a resin composition and a biodegradable molded article molded therefrom. [Background technology]

[0003] Thermoplastic resins have excellent mechanical and chemical properties and are used in a variety of fields, including drinking water containers, medical applications, food wrapping paper, food containers, automotive molded parts, and agricultural vinyl.

[0004] Among these, polyethylene films and the like are primarily used for hot sealing bags for packaging food and agricultural mulching films because they have excellent mechanical properties, are harmless to the human body, and can be continuously deformed when heated.

[0005] Hot sealing bags for food packaging are widely used for vacuum packaging food and the like, and are mainly made of polyethylene film, which can achieve excellent bonding strength even at low sealing temperatures.

[0006] Agricultural mulching films are mainly used in mulching farming. Mulching is a material that covers the surface of the soil when cultivating agricultural crops. By covering the top surface of the soil with various materials, it is possible to block the growth of weeds and prevent diseases and pests, thereby reducing the use of pesticides. It also makes it easy to regulate the temperature of the soil, promotes the proliferation of beneficial bacteria in the soil, prevents soil erosion, and maintains soil moisture. Such mulching materials can include straw, grass and other crop leaves, polyolefin films, and the like, and generally synthetic resins such as polyethylene films are mainly used.

[0007] However, polyethylene film does not decompose in the natural environment, and there is a limit to how much it can be reused. In particular, the phenomenon in which discarded plastics such as polyethylene film flow into the ocean and are broken down into very small microplastics by the ocean currents and sunlight has become a problem recently. It is known that countless amounts of such microplastics, numbering in the billions to tens of billions, float in the ocean, and these microplastics flow into the bodies of marine organisms, accumulate in the ecosystem, and affect the entire food chain.

[0008] For this reason, interest in biodegradable plastics has been growing recently. Among them, polybutylene adipate terephthalate (hereinafter referred to as PBAT) and polylactic acid (hereinafter referred to as PLA) have attracted attention as biodegradable plastics, and efforts are being made to improve the compatibility of PBAT and PLA in biodegradable resin compositions that contain them simultaneously.

[0009] Compatibilizers for biodegradable resin compositions containing PBAT and PLA are divided into physical compatibilizers and chemical compatibilizers according to their operating principle. Typical physical compatibilizers are those that use copolymers containing PBAT or PLA. However, when using such physical compatibilizers, there is a problem that the mechanical properties are reduced because the physical compatibilizer plays a role similar to that of a plasticizer.

[0010] Chemical compatibilizers are compounds containing functional groups that react with both ends of polymers, and thus act as chain extenders, increasing the molecular weight. However, if the reaction of the functional groups is carried out excessively, the viscosity of the resin composition increases rapidly, making processing difficult. Therefore, in the case of conventional chemical compatibilizers, the amount of use in the resin composition is generally extremely limited.

[0011] Meanwhile, Korean Patent Publication No. 10-2045863 (Patent Document 1) discloses a biodegradable polyester film containing a copolymer containing an epoxy group and based on styrene, an acrylic acid ester, and / or a methacrylic acid ester. When the copolymer disclosed in Patent Document 1 is used as a compatibilizer for PBAT and PLA, when used in a certain amount or more, not only PBAT-g-PLA is formed at the interface between PBAT and PLA, but also a large amount of PBAT-g-PBAT and / or PLA-g-PLA is formed in each resin, causing a problem of a sudden increase in viscosity of the resin composition. Such a sudden increase in viscosity is difficult to control during processing of the resin composition, which limits the expansion of the use of the resin composition. Therefore, it is important to secure a compatibilizer that can maintain its performance as a chemical compatibilizer in a biodegradable resin composition containing different biodegradable resins and can control the increase in viscosity within an appropriate range to ensure processability. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] KR10-2045863 B1 Summary of the Invention [Problem to be solved by the invention]

[0013] The present application has been devised to solve the problems of the prior art, and aims to improve the compatibility between different biodegradable resins in a biodegradable resin composition containing different biodegradable resins, and to adjust the melt index and the number of domains of the dispersed phase, thereby improving mechanical properties and preventing an increase in viscosity of the resin composition.

[0014] That is, the present application aims to provide a biodegradable resin composition containing different types of biodegradable resins, which has improved compatibility, thereby adjusting the melt index and the number of domains of the dispersed phase, improving mechanical properties, preventing an increase in the viscosity of the resin composition, and also providing an excellent processability.

[0015] Another object of the present invention is to provide a molded article that exhibits biodegradability by being molded from the resin composition. [Means for solving the problem]

[0016] In order to solve the above problems, the present application provides a resin composition and a molded article.

[0017] (1) The present application provides a resin composition comprising a continuous phase and a dispersed phase, wherein the continuous phase comprises a first biodegradable resin and the dispersed phase comprises a second biodegradable resin, the resin composition having a melt index of 3.0 g / 10 min to 13.5 g / 10 min as measured in accordance with ISO 1133 at 190° C. under a load of 5 kg, and wherein the number of domains of the dispersed phase observed in an image taken at a magnification of 25,000 using a transmission electron microscope (TEM) is 35 or more.

[0018] (2) The present application provides a resin composition according to the above-mentioned (1), wherein the first biodegradable resin contains an aliphatic polyester unit and an aromatic polyester unit.

[0019] (3) The present application provides a resin composition according to the above (1) or (2), wherein the first biodegradable resin contains polybutylene adipate terephthalate.

[0020] (4) The present application provides a resin composition according to any one of the above (1) to (3), wherein the second biodegradable resin contains polylactic acid.

[0021] (5) The present application provides a resin composition according to any one of (1) to (4) above, wherein the resin composition contains the first biodegradable resin in an amount of 50 parts by weight or more and 90 parts by weight or less, and the second biodegradable resin in an amount of 10 parts by weight or more and 50 parts by weight or less, relative to 100 parts by weight in total of the first biodegradable resin and the second biodegradable resin.

[0022] (6) The present application provides a resin composition according to any one of the above items (1) to (5), wherein the resin composition has a melt index of 4.5 g / 10 min or more and 12.0 g / 10 min or less, as measured at 190° C. under a load of 5 kg in accordance with ISO 1133.

[0023] (7) The present application provides a resin composition according to any one of (1) to (6) above, wherein the size of the domain of the dispersed phase observed in an image taken at a magnification of 25,000 using a transmission electron microscope (TEM) is 700 nm or less.

[0024] (8) In any one of the above (1) to (7), the present application provides a resin composition having a melting enthalpy (△Hm) of 0.01 J / g or more and 3.6 J / g or less, measured using a differential scanning calorimeter (DSC) by adding 8 mg (error range 1 mg) of a sample, primarily heating the sample to 180°C at a heating rate of 10°C / min under a nitrogen flow, cooling the sample to -50°C at a heating rate of 10°C / min, and then secondarily heating the sample to 180°C at a heating rate of 10°C / min.

[0025] (9) The present application provides a resin composition according to any one of the above (1) to (8), wherein the resin composition has a weight average molecular weight of 137,000 or more and 200,000 or less.

[0026] (10) In any one of the above (1) to (9), the resin composition has a tensile strength of 245 kgf / cm2 measured at a tensile speed of 50 mm / min in accordance with ASTM D638. 2 More than 500kgf / cm 2 The following resin composition is provided:

[0027] (11) The present application provides a resin composition according to any one of (1) to (10), further comprising at least one of an acrylic copolymer and a compatibilizing part formed from the acrylic copolymer.

[0028] (12) The present application provides a resin composition according to the above (11), wherein the acrylic copolymer contains methyl (meth)acrylate monomer units, (meth)acrylate monomer units containing an epoxy group, and alkyl (meth)acrylate monomer units having 2 to 10 carbon atoms.

[0029] (13) The present application provides a resin composition according to (11) or (12), wherein the acrylic copolymer contains 25% by weight or more and 65% by weight or less of methyl (meth)acrylate monomer units, 15% by weight or more and 60% by weight or less of (meth)acrylate monomer units containing an epoxy group, and 5% by weight or more and 32% by weight or less of alkyl (meth)acrylate monomer units having 2 to 10 carbon atoms.

[0030] (14) The present application provides a resin composition according to any one of (11) to (13), wherein the resin composition contains the acrylic copolymer and a compatibilizing part derived from the acrylic copolymer in an amount of 0.01 part by weight or more and 10.0 parts by weight or less per 100 parts by weight in total of the first biodegradable resin and the second biodegradable resin.

[0031] (15) The present application provides the resin composition according to any one of the above (11) to (14), wherein the acrylic copolymer has an epoxy equivalent weight (EEW) of 200 g / eq or more and 800 g / eq or less.

[0032] (16) The present application provides the resin composition according to any one of the above (11) to (15), wherein the acrylic copolymer has a weight average molecular weight of 10,000 or more and 100,000 or less.

[0033] (17) The present application provides the resin composition according to any one of the above (11) to (16), wherein the acrylic copolymer has a glass transition temperature of 45° C. or higher and 85° C. or lower.

[0034] (18) The present application provides a molded article molded from the resin composition according to any one of (1) to (17) above. Effect of the Invention

[0035] The resin composition of the present application is a biodegradable resin composition containing different types of biodegradable resins, and by improving the compatibility between the different types of biodegradable resins, the melt index and the number of domains of the dispersed phase are adjusted, the mechanical properties are improved, and an increase in the viscosity of the resin composition is prevented, resulting in excellent processability.

[0036] Furthermore, a molded article made from the resin composition of the present application has excellent mechanical properties and exhibits biodegradability. [Brief description of the drawings]

[0037] [Figure 1] 1 is an image of the resin composition produced in Example 2 of the present invention taken at a magnification of 25,000 using a transmission electron microscope. [Diagram 2] 1 is a transmission electron microscope image of Example 2 of the present invention, showing domains for measuring the number and size of domains. [Diagram 3] 1 is an image of the resin composition prepared in Comparative Example 1 of the present invention, taken at a magnification of 25,000 using a transmission electron microscope. [Figure 4] 1 is a transmission electron microscope image of Comparative Example 1 of the present invention, showing domains for measuring the number and size of domains. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In the following, the present invention will be described in more detail in order to facilitate understanding of the present invention.

[0039] The terms and words used in the description of the present invention and the claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0040] In the present invention, the term "monomer unit" may refer to a component, structure, or substance itself derived from a monomer, and as a specific example, may refer to a repeating unit formed in a polymer by an input monomer participating in a polymerization reaction during polymerization of a polymer.

[0041] As used herein, the term "composition" is inclusive of mixtures of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0042] The present invention provides a resin composition.

[0043] The resin composition may be a biodegradable resin composition containing different kinds of biodegradable resins. As a specific example, the resin composition may include a continuous phase and a dispersed phase, the continuous phase may include a first biodegradable resin, the dispersed phase may include a second biodegradable resin, and the melt index measured at 190° C. under a load of 5 kg according to ISO 1133 may be 3.0 g / 10 min or more and 13.5 g / 10 min or less, and the number of domains of the dispersed phase observed in an image taken at a magnification of 25,000 using a transmission electron microscope (TEM) may be 35 or more.

[0044] The resin composition may be a resin composition in which a dispersed phase formed by including the second biodegradable resin is dispersed in a continuous phase formed by including the first biodegradable resin. The first biodegradable resin and the second biodegradable resin are different types of biodegradable resins, and any resin known as a biodegradable resin may be used. As a specific example, the first biodegradable resin may be a polyester-based resin containing an aliphatic polyester unit and an aromatic polyester unit. As a more specific example, the first biodegradable resin may contain polybutylene adipate terephthalate (PBAT). PBAT is a random copolymer of adipic acid, 1,4-butanediol, and terephthalic acid, and has been proposed as an alternative biodegradable resin to low-density polyethylene. In particular, the PBAT can ensure biodegradability from the aliphatic polyester unit formed by adipic acid and 1,4-butanediol, and mechanical properties from the aromatic polyester unit formed by terephthalic acid and 1,4-butanediol.

[0045] The second biodegradable resin may be any resin different from the first biodegradable resin, and as a specific example, the second biodegradable resin may include polylactic acid (PLA). PLA is an environmentally friendly biodegradable resin that is produced from biomaterials and naturally decomposes into water and carbon dioxide within a few months through the action of microorganisms.

[0046] The resin composition may contain the first biodegradable resin in an amount of 50 parts by weight or more and 90 parts by weight or less, based on 100 parts by weight of the first biodegradable resin and the second biodegradable resin in total. As a specific example, the resin composition may contain the first biodegradable resin in an amount of 50 parts by weight or more, 55 parts by weight or more, 60 parts by weight or more, 65 parts by weight or more, or 70 parts by weight or more, based on 100 parts by weight of the first biodegradable resin and the second biodegradable resin in total, and may contain the first biodegradable resin in an amount of 90 parts by weight or less, 85 parts by weight or less, or 80 parts by weight or less, based on 100 parts by weight of the first biodegradable resin and the second biodegradable resin in total. Within this range, the mechanical properties and processability may be further excellent.

[0047] The resin composition may contain 10 to 50 parts by weight of the second biodegradable resin relative to 100 parts by weight of the first and second biodegradable resins in total. As a specific example, the resin composition may contain 10 to 20 parts by weight of the second biodegradable resin relative to 100 parts by weight of the first and second biodegradable resins in total, or 50 to 45 parts by weight, 40 to 35 parts by weight, or 30 to 50 parts by weight, and within this range, the mechanical properties and processability may be further improved.

[0048] The resin composition may have a melt index of 3.0 g / 10 min or more and 13.5 g / 10 min or less, measured at 190 ° C. under a load of 5 kg according to ISO 1133. The melt index indicates viscosity, which is one of the indices showing the compatibility between different biodegradable resins in the resin composition, and when the viscosity of the resin composition increases, the melt index decreases. That is, a low melt index means a high viscosity, and a low melt index may increase the viscosity and reduce processability. The epoxy group of the acrylic copolymer described below can react with the carboxylic acid group of polybutylene adipate terephthalate and / or polylactic acid. Here, when the reaction is carried out at the interface of polybutylene adipate terephthalate and / or polylactic acid, a polymerization form of a graft polymer such as polybutylene adipate terephthalate-g-polylactic acid (PBAT-g-PLA) is formed, which strengthens the interfacial adhesion and enhances the compatibility between polybutylene adipate terephthalate and polylactic acid. In other words, when the melt index is within the range defined in the present invention, it indicates that a graft polymer such as polybutylene adipate terephthalate-g-polylactic acid (PBAT-g-PLA) is formed within the appropriate range.As a specific example, the resin composition may have a melt index, measured in accordance with ISO 1133 at 190° C. under a load of 5 kg, of 3.0 g / 10 min or more, 3.5 g / 10 min or more, 4.0 g / 10 min or more, 4.5 g / 10 min or more, or 4.8 g / 10 min or more, and may also have a melt index of 13.5 g / 10 min or less, 13.4 g / 10 min or less, 13.3 g / 10 min or less, 13.2 g / 10 min or less, 13.1 g / 10 min or less, 13.0 g / 10 min or less, 12.9 g / 10 min or less, 12.8 g / 10 min or less, 12.7 g / 10 min or less, or Within this range, the compatibility between different types of biodegradable resins is improved, thereby improving the mechanical properties and preventing an increase in the viscosity of the resin composition, thereby providing further excellent processability.

[0049] The resin composition may have 35 or more domains of the dispersed phase observed in an image taken at 25,000 times magnification using a transmission electron microscope (TEM). When the resin composition is observed using a transmission electron microscope, the dispersed phase containing the second biodegradable resin forms domains in the continuous phase containing the first biodegradable resin. Here, the number of domains of the dispersed phase dispersed in the same continuous phase changes depending on the compatibility between the first biodegradable resin and the second biodegradable resin. That is, the more excellent the compatibility between the first biodegradable resin and the second biodegradable resin, the more the number of domains of the dispersed phase dispersed in the same continuous phase increases. As a specific example, the resin composition may have a number of domains of the dispersed phase observed in an image taken at 25,000 times magnification using a transmission electron microscope (TEM) of 35 or more, 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, 70 or more, 75 or more, 80 or more, 85 or more, 90 or more, 95 or more, or 100 or more. The upper limit is not particularly limited, but may be 1,000 or less, 900 or less, 800 or less, 700 or less, 600 or less, 500 or less, 400 or less, 300 or less, 200 or less, or 150 or less. Within this range, the compatibility between different biodegradable resins is improved, mechanical properties are improved, and an increase in the viscosity of the resin composition is prevented, resulting in more excellent processability. Here, the image taken at a magnification of 25,000 using the transmission electron microscope (TEM) may be an image with a horizontal (minor axis) of 3.4 μm and a vertical (major axis) of 4.9 μm. When the number of domains is measured using the image taken at a magnification of 25,000 using the transmission electron microscope (TEM), the domains to be measured may be domains that have a brightness of 9 or more, when brightness is divided into black as 0 and white as 10, among the domains whose major axis length is 150 nm or more in the transmission electron microscope image, and the size of the domains is the arithmetic average value of the size based on the major axis of each domain. As a specific example, the domains may be polylactic acid, and the matrix, which is the continuous phase, may be polybutylene adipate terephthalate.The domains may be a feature that can be estimated from the difference in glass transition temperature and melt viscosity between polylactic acid and polybutylene adipate terephthalate. As a more specific example, the domains may correspond to morphological characteristics that appear due to the clear difference in fluidity between the two resins under the same processing conditions, since the glass transition temperature of polybutylene adipate terephthalate is low (about -30°C) while the glass transition temperature of polylactic acid is high (about 60°C). In addition, the polylactic acid, which is the dispersed phase observed in the image observed through a transmission electron microscope, is confirmed to be bright in color, and therefore it can be estimated that the influence of the transmission beam is stronger than that of polybutylene adipate terephthalate resin.

[0050] The resin composition may have a dispersed phase domain size of 700 nm or less as observed in an image taken at 25,000 magnifications using a transmission electron microscope (TEM). The size of the dispersed phase domain dispersed in the same continuous phase varies depending on the compatibility of the first and second biodegradable resins. That is, the better the compatibility of the first and second biodegradable resins, the smaller the size of the dispersed phase domain dispersed in the same continuous phase. As a specific example, the resin composition may have a domain size of the dispersed phase observed in an image taken at 25,000 magnification using a transmission electron microscope (TEM) of 700 nm or less, 650 nm or less, 500 nm or less, 450 nm or less, or 400 nm or less, and the lower limit is not particularly limited, but may be 10 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, or 200 nm or more, and within this range, the compatibility between different biodegradable resins is improved, mechanical properties are improved, and the viscosity of the resin composition is prevented from increasing, resulting in more excellent processability. Here, the criteria for selecting the image size and domain are as described above, and the domain size may mean that the size based on the major axis of each domain of the dispersed phase observed in an image taken at 25,000 magnification using a transmission electron microscope (TEM) is within the above range, or the arithmetic average value of the domain size is within the above range.

[0051] The resin composition may have a melting enthalpy (ΔHm) of 0.01 J / g or more and 3.6 J / g or less, as measured by using a differential scanning calorimeter (DSC) to insert a sample of 8 mg (error range 1 mg), and subjecting the sample to a nitrogen flow and primary heating at a heating rate of 10°C / min to 180°C, followed by cooling to -50°C at a heating rate of 10°C / min, and secondary heating at a heating rate of 10°C / min to 180°C. The melting enthalpy (ΔHm) is an index indicating the compatibility between different biodegradable resins in the resin composition in addition to the melt index, and may be, for example, the melting enthalpy (ΔHm) generated during the cold crystallization process of the second biodegradable resin, or, more specifically, polylactic acid. When the resin composition contains different biodegradable resins, the crystallinity of the second biodegradable resin decreases due to the compatibility between them, which leads to a decrease in the cold crystallization peak and a decrease in the melting enthalpy. The melting enthalpy (ΔHm) is thus measured based on the degree of melting (ΔHm) due to the cold crystallization, which changes depending on the compatibility of different biodegradable resins in the resin composition. The lower the melting enthalpy (ΔHm), the better the compatibility of different biodegradable resins in the resin composition. As a specific example, the resin composition is measured using a differential scanning calorimeter (DSC) by inserting 8 mg (with an error range of 1 mg) of a sample, heating it to 180°C at a heating rate of 10°C / min under a nitrogen gas flow, cooling it to -50°C at a heating rate of 10°C / min, and then heating it to 180°C at a heating rate of 10°C / min. The melting enthalpy (ΔHm) is 0.01 J / g or more, 0.02 J / g or more, 0.03 J / g or more, It can be 0.04 J / g or more, 0.05 J / g or more, 0.06 J / g or more, 0.07 J / g or more, 0.08 J / g or more, 0.09 J / g or more, or 0.1 J / g or more, and can be 3.6 J / g or less, or 3.5 J / g or less. Within this range, the compatibility between different types of biodegradable resins is improved, thereby improving the mechanical properties and preventing an increase in the viscosity of the resin composition, thereby further improving the processability.

[0052] The resin composition may have a weight average molecular weight of the entire resin composition of 137,000 or more and 200,000 or less. As a specific example, the weight average molecular weight of the entire resin composition may be 137,000 or more, 137,500 or more, or 138,000 or more, and may be 200,000 or less, 195,000 or less, 190,000 or less, 185,000 or less, 180,000 or less, 175,000 or less, 170,000 or less, 165,000 or less, 160,000 or less, or 159,000 or less. Within this range, a graft polymer such as polybutylene adipate terephthalate-g-polylactic acid (PBAT-g-PLA) is formed at an appropriate level in a different biodegradable resin, particularly polybutylene adipate terephthalate and / or polylactic acid, to increase the molecular weight and further improve the tensile strength of the resin composition. The weight average molecular weight can be expressed without units, but depending on the molar mass, it can be expressed in units of g / mol.

[0053] The resin composition has a tensile strength of 245 kgf / cm2 measured at a tensile speed of 50 mm / min according to ASTM D638. 2 More than 500kgf / cm 2 As a specific example, the resin composition may have a tensile strength of 245 kgf / cm or less as measured in accordance with ASTM D638. 2 Above, 250kgf / cm 2 Above, 255kgf / cm 2 or more, or 260kgf / cm 2 It can be more than 500kgf / cm 2 Below, 490kgf / cm 2 Below, 480kgf / cm 2 Below, 470kgf / cm 2 Below, 460kgf / cm 2 Below, 450kgf / cm 2 Below, 440kgf / cm 2 Below, 430kgf / cm 2 Below, 420kgf / cm 2 or less than 415kgf / cm 2It can be the following:

[0054] The resin composition may have an elongation of 400% or more as measured in accordance with ASTM D638. As a specific example, the resin composition may have an elongation of 400% or more, 410% or more, 420% or more, 430% or more, 440% or more, 450% or more, 460% or more, 470% or more, 480% or more, 490% or more, 500% or more, 510% or more, 520% ​​or more, 530% or more, 540% or more, 550% or more, 560% or more, 570% or more, 580% or more, or 590% or more as measured in accordance with ASTM D638, and may be 700% or less, 690% or less, 680% or less, 670% or less, or 665% or less.

[0055] The resin composition may further include at least one of an acrylic copolymer and a compatibilizer formed from the acrylic copolymer.

[0056] The acrylic copolymer is a copolymer containing a reactive functional group such as an epoxy group, and can be included as a chemical compatibilizer to improve compatibility with PBAT and PLA in the resin composition. The acrylic copolymer may be present as itself in the resin composition, or may be present in the form of a compatibilizer formed by chemical bonding by reacting the reactive functional group with the first biodegradable resin and the second biodegradable resin, or both forms may coexist.

[0057] The acrylic copolymer may be an acrylic copolymer copolymerized with a methyl (meth)acrylate monomer, a (meth)acrylate monomer containing an epoxy group, and an alkyl (meth)acrylate monomer having 2 to 10 carbon atoms. As a specific example, the acrylic copolymer may be a random copolymer copolymerized with a methyl (meth)acrylate monomer, a (meth)acrylate monomer containing an epoxy group, and an alkyl (meth)acrylate monomer having 2 to 10 carbon atoms, and may be a linear random copolymer. Here, "(meth)acrylate" means both acrylate and methacrylate.

[0058] The acrylic copolymer may contain methyl (meth)acrylate monomer units in an amount of 25% by weight or more and 65% by weight or less. As a specific example, the acrylic copolymer may contain methyl (meth)acrylate monomer units formed from methyl (meth)acrylate monomers in an amount of 25% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more, or 65% by weight or less, 60% by weight or less, 55% by weight or less, or 50% by weight or less. Within this range, the copolymer has excellent miscibility with the second biodegradable resin and relatively excellent affinity with the first biodegradable resin, and can further improve the compatibility between the first biodegradable resin and the second biodegradable resin.

[0059] The acrylic copolymer may contain 15% by weight or more and 60% by weight or less of (meth)acrylate monomer units containing an epoxy group formed from a (meth)acrylate monomer containing an epoxy group. As a specific example, the acrylic copolymer may contain 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more of (meth)acrylate monomer units containing an epoxy group formed from a (meth)acrylate monomer containing an epoxy group, and may contain 60% by weight or less, 55% by weight or less, 50% by weight or less, or 45% by weight or less. Within this range, the flexibility of the polymer chain can be increased, the compatibility of the first biodegradable resin and the second biodegradable resin can be further improved, and in particular, when a film is produced from the resin composition, the chain diffusion and entanglement between the film interfaces can be increased.

[0060] The (meth)acrylate monomer containing an epoxy group may be a (meth)acrylate monomer containing a glycidyl group, and a specific example of the (meth)acrylate monomer may be a glycidyl (meth)acrylate monomer. The (meth)acrylate monomer containing an epoxy group may function as a chemical compatibilizer by reacting the epoxy group contained in the monomer with a hydroxyl group (-OH) or a carboxylic acid group (-COOH) contained in the first or second biodegradable resin. In addition, when the reaction occurs at the interface between the first and second biodegradable resins, the compatibility and interfacial adhesion between the first and second biodegradable resins may be further improved.

[0061] The acrylic copolymer may contain 5% by weight or more and 32% by weight or less of alkyl (meth)acrylate monomer units having 2 to 10 carbon atoms formed from alkyl (meth)acrylate monomers having 2 to 10 carbon atoms. As a specific example, the acrylic copolymer may contain 5% by weight or more, 10% by weight or more, or 15% by weight or more of alkyl (meth)acrylate monomer units having 2 to 10 carbon atoms formed from alkyl (meth)acrylate monomers having 2 to 10 carbon atoms, or 32% by weight or less, 31% by weight or less, 30% by weight or less, 25% by weight or less, or 20% by weight or less of alkyl (meth)acrylate monomer units having 2 to 10 carbon atoms formed from alkyl (meth)acrylate monomers having 2 to 10 carbon atoms. Within this range, the flexibility of the polymer chain can be increased, the compatibility of the first biodegradable resin and the second biodegradable resin can be further improved, and in particular, when a film is produced from the resin composition, the chain diffusion and entanglement between the film interfaces can be increased.

[0062] The alkyl (meth)acrylate monomer having 2 to 10 carbon atoms may be at least one selected from the group consisting of ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, iso-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, iso-decyl (meth)acrylate, dodecyl (meth)acrylate, iso-bornyl (meth)acrylate, and lauryl (meth)acrylate. As a specific example, the alkyl (meth)acrylate monomer having 2 to 10 carbon atoms may be an alkyl (meth)acrylate monomer having 3 to 9 or 4 to 8 carbon atoms, and as a more specific example, it may be one or more selected from the group consisting of butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.

[0063] The acrylic copolymer may be prepared by emulsion polymerization of a monomer mixture including the methyl (meth)acrylate monomer, the (meth)acrylate monomer containing an epoxy group, and the alkyl (meth)acrylate monomer having 2 to 10 carbon atoms, a polymerization initiator, an emulsifier, and the like.

[0064] The polymerization temperature and time during the polymerization of the acrylic copolymer may be adjusted as required. For example, the polymerization temperature may be within a range of 50° C. to 200° C., and the polymerization time may be within a range of 0.5 hours to 20 hours.

[0065] The polymerization initiator may be an inorganic or organic peroxide, and specific examples thereof include water-soluble polymerization initiators including potassium persulfate, sodium persulfate, and ammonium persulfate, and oil-soluble polymerization initiators including cumene hydroperoxide and benzoyl peroxide.

[0066] In order to promote the initiation of the reaction of the peroxide together with the polymerization initiator, an activator may be used together. As the activator, one or more selected from the group consisting of sodium formaldehyde sulfoxylate, sodium ethylenediaminetetraacetate, ferrous sulfate, and dextrose may be used.

[0067] The polymerization initiator may be added in an amount of 0.1 to 10 parts by weight, specifically 0.1 to 5 parts by weight, based on 100 parts by weight of the monomer mixture, on a dry weight basis.

[0068] The polymerization may be carried out by further including a chain transfer agent in order to increase the efficiency of the polymerization reaction. The chain transfer agent may play a role of introducing a homopolymer, which is a polymer composed of only one type of monomer, into a micelle during the polymerization process. The chain transfer agent may be a linear or branched alkylthiol compound having 5 to 20 carbon atoms, and specific examples thereof may include hexanethiol, cyclohexanethiol, adamantanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol, hexadecanethiol, and octadecanethiol. The chain transfer agent may be added in an amount of 0.1 to 10 parts by weight, and specific examples thereof may be 0.1 to 5 parts by weight, based on the dry weight, relative to 100 parts by weight of the monomer mixture.

[0069] The emulsion polymerization may be carried out including the following steps (S10) to (S30).

[0070] (S10) Step: A step of dispersing an emulsifier in a solvent to produce an emulsion (S20) Step: A step of preparing a pre-emulsion by mixing a monomer mixture containing each monomer component and an emulsifier, etc. (S30) step: A step of mixing the emulsion prepared in the (S10) step and the pre-emulsion prepared in the (S20) step in the presence of a polymerization initiator to carry out emulsion polymerization.

[0071] The emulsion polymerization for polymerizing the acrylic copolymer may be carried out through steps (S10) to (S30).

[0072] First, in step (S10), an emulsion containing an emulsifier is prepared. This is different from the process of preparing a pre-emulsion described below. The emulsifier may be an anionic emulsifier alone or may be an anionic emulsifier, a cationic emulsifier, and a non-ionic emulsifier together, and the emulsion may be prepared by mixing the emulsifier components and a solvent such as water. In the process of preparing the emulsion, micelle initial particles of several nanometers in size may be stably formed. In addition, in step (S20), a pre-emulsion containing the monomer mixture is prepared by mixing the above-mentioned monomers, emulsifier, etc. with water. In this case, the emulsifier may be an anionic emulsifier alone or may be an anionic emulsifier and the above-mentioned non-ionic emulsifier together. In this process, nano-sized latex particles may be formed in the pre-emulsion. That is, the emulsifier may be used in at least one of the steps of preparing the emulsion and the step of preparing the pre-emulsion. In addition, in step (S30), a polymerization initiator is added to the prepared emulsion, and then the pre-emulsion and the polymerization initiator are continuously added in equal ratios for a predetermined period of time.

[0073] The content of the polymerization initiator added to the emulsion may be more than 0 to 1 part by weight based on 100 parts by weight of the monomer mixture, and the content of the polymerization initiator added together with the pre-emulsion may be 0.1 to 2 parts by weight based on 100 parts by weight of the monomer mixture, and the continuous addition time may be about 3 to 7 hours. Through this process, the floating monomer or polymer in the pre-emulsion may flow into the initial particles generated in the emulsion. The result of this reaction may then be subjected to a thermal polymerization process in the presence of an additional polymerization initiator, whereby the remaining monomer is polymerized. Here, the polymerization initiator may be further added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the monomer mixture, and the thermal polymerization may be performed at a temperature of about 75°C to about 85°C for about 40 to about 80 minutes. Such an emulsion polymerization method is divided into a process for preparing an emulsion and a process for preparing a pre-emulsion, and can be carried out by a simple method of subsequently mixing the pre-emulsion with the emulsion, thereby improving process stability and productivity compared to conventional methods.

[0074] The emulsifier used in the emulsion polymerization may include at least one selected from the group consisting of anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers. The emulsifier is a material having both a hydrophilic group and a hydrophobic group, and forms a micelle structure during the emulsion polymerization, allowing the polymerization of each monomer to occur inside the micelle structure. Emulsifiers commonly used in emulsion polymerization are classified into anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers, and two or more of them may be mixed together to improve polymerization stability during emulsion polymerization. As a specific example, the nonionic emulsifier may include at least one selected from the group consisting of polyethylene oxide alkyl aryl ethers, polyethylene oxide alkyl amines, and polyethylene oxide alkyl esters. The anionic emulsifier may include one or more selected from the group consisting of sodium alkyl diphenyl ether disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene aryl ether sulfate, sodium alkyl sulfate, sodium alkyl benzene sulfonate, and dialkyl sodium sulfosuccinate. These may be used alone or in combination of two or more, and may be more effective when an anionic emulsifier and a nonionic emulsifier are used in combination. The emulsifier may be used in an amount of about 0.1 parts by weight to about 10 parts by weight, or about 1 part by weight to about 5 parts by weight, based on 100 parts by weight of the total monomer components used in the production of the latex particles.

[0075] The polymerization composition may further include an aqueous solvent such as water in addition to the emulsifier or monomer component. Here, the aqueous solvent may be used in an amount of about 10 to about 1,000 parts by weight based on 100 parts by weight of the latex particles in terms of adjusting the stability and viscosity of the latex particles, and may be used so that the total solid content (TSC) is adjusted to about 10% by weight to about 60% by weight based on the total amount of the composition.

[0076] The resin composition may contain the acrylic copolymer and the compatibilizing portion derived from the acrylic copolymer in a content of 0.01 parts by weight or more and 10.0 parts by weight or less, based on a total of 100 parts by weight of the first biodegradable resin and the second biodegradable resin. As a specific example, the resin composition may contain the acrylic copolymer and the compatibilizing portion derived from the acrylic copolymer in a content of 0.01 parts by weight or more, 0.02 parts by weight or more, 0.03 parts by weight or more, 0.04 parts by weight or more, 0.05 parts by weight or more, 0.06 parts by weight or more, 0.07 parts by weight or more, 0.08 parts by weight or more, 0.09 parts by weight or more, or 0.1 parts by weight or more, based on a total of 100 parts by weight of the first biodegradable resin and the second biodegradable resin, and may also contain 10.0 parts by weight or less. , 9.0 parts by weight or less, 8.0 parts by weight or less, 7.0 parts by weight or less, 6.0 parts by weight or less, 5.0 parts by weight or less, 4.5 parts by weight or less, 4.0 parts by weight or less, 3.5 parts by weight or less, 3.0 parts by weight or less, 2.5 parts by weight or less, 2.0 parts by weight or less, 1.5 parts by weight or less, or 1.0 parts by weight or less. Within this range, the compatibility between different biodegradable resins is further improved, thereby further improving the mechanical properties, and an increase in the viscosity of the resin composition is prevented, resulting in more excellent processability.

[0077] The acrylic copolymer may have an epoxy equivalent weight (EEW) of 200 g / eq or more and 800 g / eq or less. As a specific example, the acrylic copolymer may have an epoxy equivalent weight (EEW) of 200 g / eq or more, 210 g / eq or more, 220 g / eq or more, 230 g / eq or more, 240 g / eq or more, 250 g / eq or more, 260 g / eq or more, 270 g / eq or more, 280 g / eq or more, 290 g / eq or more, 300 g / eq or more, 310 g / eq or more, 320 g / eq or more, 330 g / eq or more, 340 g / eq or more, or 350 g / eq or more, and may have an epoxy equivalent weight (EEW) of 800 g / eq or less, 70 It can be 0g / eq or less, 600g / eq or less, 500g / eq or less, 490g / eq or less, 480g / eq or less, 470g / eq or less, 460g / eq or less, 450g / eq or less, 440g / eq or less, 430g / eq or less, 420g / eq or less, 410g / eq or less, 400g / eq or less, 390g / eq or less, 380g / eq or less, 370g / eq or less, or 360g / eq or less, and within this range, the compatibility between different biodegradable resins can be further improved. In particular, when the biodegradable resin is a polyester resin, it can effectively react with the hydroxyl group or carboxylic acid group of the polyester resin, and further improve its performance as a chemical compatibilizer.

[0078] The acrylic copolymer may have a weight average molecular weight of 10,000 or more and 100,000 or less. As a specific example, the acrylic copolymer may have a weight average molecular weight of 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more, or 30,000 or more, or 100,000 or less, 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 50,000 or less, or 40,000 or less. Within this range, the inherent properties of different biodegradable resins, particularly polyester resins, are not impaired, and the function as a chemical compatibilizer may be more excellent. The weight average molecular weight may be expressed without a unit, but may be expressed in units of g / mol depending on the molar mass.

[0079] The acrylic copolymer may have a glass transition temperature of 45° C. or more and 85° C. or less. As a specific example, the acrylic copolymer may have a glass transition temperature of 45° C. or more, 46° C. or more, 47° C. or more, 48° C. or more, 49° C. or more, 50° C. or more, 51° C. or more, 52° C. or more, 53° C. or more, 54° C. or more, 55° C. or more, 56° C. or more, 57° C. or more, 58° C. or more, or 59° C. or more, and may have a glass transition temperature of 85° C. or less, 84° C. or less, 83° C. or less, 82° C. or less, 81° C. or less, 80° C. or less, 79° C. or less, 78° C. or less, 77° C. or less, 76° C. or less, 75° C. or less, 74° C. or less, 73° C. or less, 72° C. or less, 71° C. or less, or 70° C. or less, and within this range, it may be easier to process into a compatibilizer for a resin composition containing a different type of biodegradable resin.

[0080] The present invention provides a molded article.

[0081] The molded article may be a biodegradable molded article molded from the resin composition, i.e., a biodegradable resin composition. Here, the molded article includes not only an injection molded article formed by injection or the like, but also a film molded article formed by film formation.

[0082] The molded article may be a biodegradable film, and specific examples thereof include an agricultural mulching film and a film for use as a food packaging material.

[0083] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to exemplary embodiments thereof, so that those skilled in the art can easily practice the present invention. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0084] Production examples and comparative production examples: Production of acrylic copolymers Manufacturing Example 1 In a 3L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 200 parts by weight of distilled water and 0.5 parts by weight of sodium dioctyl sulfosuccinate (sodium bis(2-ethylhexyl) sulfosuccinate) as an emulsifier were added to a total of 100 parts by weight of monomers methyl methacrylate, glycidyl methacrylate, butyl acrylate and 2-ethylhexyl acrylate, and the mixture was stirred. After the inside of the reactor was replaced with nitrogen gas while stirring, the glass reactor was heated to 70°C, 0.2 parts by weight of potassium persulfate was added, and the mixture was maintained for 10 minutes.

[0085] Separately, 45 parts by weight of methyl methacrylate, 40 parts by weight of glycidyl methacrylate, and 15 parts by weight of butyl acrylate were added to a beaker and thoroughly mixed for 30 minutes, and 0.5 parts by weight of 1-octanethiol was added as a chain transfer agent relative to the total of 100 parts by weight of the monomers, and after thoroughly mixing with a stirrer, the mixture was continuously added to the glass reactor at equal intervals for 4 hours.

[0086] After 4 hours of polymerization reaction, the temperature inside the glass reactor was maintained at 70°C for 30 minutes and then cooled to room temperature. The emulsion polymerization product was coagulated using an aqueous calcium acetate solution, heated to 85°C, dehydrated, and dried at 60°C for 16 hours to obtain an acrylic copolymer.

[0087] Manufacturing Example 2 An acrylic copolymer was obtained in the same manner as in Preparation Example 1, except that 15 parts by weight of 2-ethylhexyl acrylate was used instead of 15 parts by weight of butyl acrylate.

[0088] Production Example 3 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 55 parts by weight of methyl methacrylate was added instead of 45 parts by weight, and 30 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight.

[0089] Production Example 4 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 30 parts by weight of methyl methacrylate was added instead of 45 parts by weight, and 55 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight.

[0090] Production Example 5 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 30 parts by weight of methyl methacrylate was added instead of 45 parts by weight, 55 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight, and 15 parts by weight of 2-ethylhexyl acrylate was added instead of 15 parts by weight of butyl acrylate.

[0091] Production Example 6 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 55 parts by weight of methyl methacrylate was added instead of 45 parts by weight, 20 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight, and 25 parts by weight of 2-ethylhexyl acrylate was added instead of 15 parts by weight of butyl acrylate.

[0092] Comparative Manufacturing Example 1 A commercially available copolymer (a copolymer of methyl methacrylate, butyl acrylate, glycidyl methacrylate and styrene) used in the production of Masterbatch A described in Patent Document 1 was used.

[0093] Comparative Manufacturing Example 2 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 64 parts by weight of methyl methacrylate was added instead of 45 parts by weight, 2.1 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight, and 33.9 parts by weight of butyl acrylate was added instead of 15 parts by weight.

[0094] Comparative Manufacturing Example 3 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 62.3 parts by weight of methyl methacrylate was added instead of 45 parts by weight, 5.2 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight, and 32.5 parts by weight of 2-ethylhexyl acrylate was added instead of 15 parts by weight of butyl acrylate.

[0095] Comparative Example 4 An acrylic copolymer was obtained by carrying out the same procedure as in Preparation Example 1, except that 60 parts by weight of methyl methacrylate was added instead of 45 parts by weight, 10 parts by weight of glycidyl methacrylate was added instead of 40 parts by weight, and 30 parts by weight of butyl acrylate was added instead of 15 parts by weight.

[0096] Examples and Comparative Examples: Production of Resin Compositions Example 1 Polybutylene adipate terephthalate (manufacturer: Xinjiang Blueridge Tunhe Chemical Industry Co., Ltd., product name: TH801T) and polylactic acid (manufacturer: Natureworks, product name: Ingeo Biopolymer 2003D) were each dried in an oven at 60° C. for 24 hours.

[0097] Next, 80 parts by weight of polybutylene adipate terephthalate, 20 parts by weight of polylactic acid, and 0.3 parts by weight of the acrylic copolymer obtained in Production Example 1 were mixed and blended for 10 minutes at 170°C and 60 rpm using a Haake Rheomix OS Lab mixer manufactured by Thermo Electron Karlsruhe GmbH. Then, the mixture was pulverized to obtain a resin composition.

[0098] Example 2 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Preparation Example 1 was used instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0099] Example 3 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Preparation Example 2 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0100] Example 4 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Preparation Example 3 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0101] Example 5 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Preparation Example 4 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0102] Example 6 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Preparation Example 5 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0103] Example 7 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Preparation Example 6 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0104] Comparative Example 1 A resin composition was obtained in the same manner as in Example 1, except that the acrylic copolymer obtained in Preparation Example 1 was not added.

[0105] Comparative Example 2 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the copolymer of Comparative Preparation Example 1 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0106] Comparative Example 3 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Comparative Preparation Example 2 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0107] Comparative Example 4 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Comparative Preparation Example 3 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0108] Comparative Example 5 A resin composition was obtained in the same manner as in Example 1, except that 1.0 part by weight of the acrylic copolymer obtained in Comparative Preparation Example 4 was added instead of 0.3 part by weight of the acrylic copolymer obtained in Preparation Example 1.

[0109] Experimental Example Experimental Example 1 The glass transition temperature, molecular weight and epoxy equivalent of the acrylic copolymers produced in Production Examples 1 to 6 and Comparative Production Examples 2 to 4 were measured by the following methods, and are shown in Table 1 below together with the monomer composition.

[0110] Furthermore, the glass transition temperature, molecular weight and epoxy equivalent of the copolymer of Comparative Production Example 1 were measured and are shown in Table 1 below.

[0111] *Glass transition temperature (℃): Using a differential scanning calorimeter (manufacturer: TA Instruments, model name: DSC 250), 8 mg (error range 1 mg) of each acrylic copolymer sample manufactured in the above Manufacturing Example and Comparative Manufacturing Example was put in, and the sample was primarily heated to 300℃ at a heating rate of 10℃ / min under a nitrogen flow, cooled to 0℃ at a heating rate of 10℃ / min, and then secondary heated to 300℃ at a heating rate of 10℃ / min to measure the glass transition temperature.

[0112] *Weight average molecular weight and number average molecular weight: The weight average molecular weight and number average molecular weight of the obtained acrylic copolymer sample were measured under the following conditions using gel permeation chromatography (GPC, PL GPC220, manufactured by Agilent Technologies). Here, the sample was prepared by taking a part of a solution dissolved in a solvent of tetrahydrofuran (stabilized with BHT) at a concentration of 2 mg / ml.

[0113] -Column: PL MiniMixed BX 2 -Solvent: Tetrahydrofuran (Stabilized with BHT) -Flow rate: 0.3ml / min -Sample concentration: 2.0mg / ml -Column temperature: 40℃ -Detector: Waters 2414 Refractive Index Detector -Data processing: Empower - Calibration curve: Polystyrene standards (molecular weight: 9 types: 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000)

[0114] *Epoxy equivalent (g / eq): Using a 700 MHz NMR spectrometer manufactured by Bruker, the content ratio (molar ratio) of glycidyl methacrylate was measured according to nuclear magnetic resonance spectroscopy, from which the number of equivalents of epoxy groups (eq / mol) was obtained, and the epoxy equivalent (g / eq) was calculated using the number average molecular weight (Mn) value measured above.

[0115] [Table 1]

[0116] Experimental Example 2 For the resin compositions produced in Examples 1 to 7 and Comparative Examples 1 to 5, the melt index, fusion enthalpy (ΔHm), and the number and size of domains were measured by the following methods, and the results are shown in Table 2 below.

[0117] *Melt index (Melt flow ratio, MFR): The melt index of the obtained resin composition sample was measured using a melt flow indexer MI-4 manufactured by Gottfert in accordance with ISO 1133 (190°C, 5 kg).

[0118] * Enthalpy of fusion (△Hm): Using a differential scanning calorimeter (DSC), 8 mg (error range 1 mg) of the obtained resin composition sample was put in and heated primarily to 180°C at a heating rate of 10°C / min under a nitrogen stream. It was then cooled to -50°C at a heating rate of 10°C / min, and heated again to 180°C at a heating rate of 10°C / min to measure the enthalpy of fusion (△Hm) generated during the cold crystallization of polylactic acid.

[0119] *Number and size of domains: A thin piece of the obtained resin composition was prepared using a microtome, and the thin piece was stained with osmium tetroxide vapour to prepare a test piece, and the test piece was photographed at 25,000 times magnification using a transmission electron microscope. The number and size of the domains were measured using the Image J program for the photographed transmission electron microscope image. Here, when measuring the number and size of the domains, the domains to be measured were selected from among the domains in the transmission electron microscope image whose major axis length is 150 nm or more, with black being 0 and white being 10, and domain size was the arithmetic average value of the size based on the major axis of each domain.

[0120] Images of the resin compositions of Example 2 and Comparative Example 1 taken at a magnification of 25,000 using the transmission electron microscope are shown in FIG. 1 (Example 2) and FIG. 3 (Comparative Example 1). Images showing domains for measuring the number and size of the domains in FIG. 1 and FIG. 3 are shown in FIG. 2 (Example 2) and FIG. 4 (Comparative Example 1), respectively.

[0121] [Table 2]

[0122] As shown in Table 2, the resin compositions prepared in Examples 1 to 7 of the present invention had melt indices in the range of 3.0 g / 10 min to 13.5 g / 10 min, fusion enthalpies in the range of 0.01 J / g to 3.6 J / g, and domains of 50 or more with domain sizes of 650 nm or less.

[0123] On the other hand, the resin compositions produced in Comparative Examples 1 and 3 to 5 were confirmed to have a melt index exceeding 13.5 g / 10 min, a fusion enthalpy exceeding 3.6 J / g, a domain number of 19 to 24, and a domain size of 700 nm or more.

[0124] In particular, it was confirmed that the resin composition prepared in Comparative Example 2 containing the copolymer of Comparative Preparation Example 1 had a very low viscosity, so that the melt index did not appear due to a sudden increase in viscosity.

[0125] Experimental Example 3 For the resin compositions produced in Examples 1 to 7 and Comparative Examples 1 to 5, the molecular weight, molecular weight distribution, tensile strength and elongation were measured by the following methods, and the results are shown in Table 3 below.

[0126] *Weight average molecular weight and molecular weight increase rate: The weight average molecular weight of the obtained resin composition sample was measured under the following conditions using gel permeation chromatography (GPC, PL GPC220, manufactured by Agilent Technologies). Here, the sample was a part of a solution dissolved in chloroform as a solvent at a concentration of 1 mg / ml.

[0127] -Column: PL MiniMixed BX 2 -Solvent: Chloroform -Flow rate: 1.0mL / min -Sample concentration: 1.0mg / ml -Column temperature: 40℃ -Detector: Waters 2414 Refractive Index Detector -Data processing: Empower - Calibration curve: Polystyrene standard (molecular weight: 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000

[0128] In addition, based on the weight average molecular weight measured for the resin composition of Comparative Example 1 not containing an acrylic copolymer, the increase rates of the weight average molecular weight measured for the resin compositions of Examples 1 to 7 and Comparative Examples 2 to 5 were calculated according to the following mathematical formula 1 and shown.

[0129] [Mathematical formula 1] Molecular weight increase rate=(weight average molecular weight measured for the resin compositions of Examples 1 to 7 and Comparative Examples 2 to 5 / weight average molecular weight measured for the resin composition of Comparative Example 1)×100

[0130] *Tensile strength and elongation: The obtained resin compositions were placed in molds measuring 130 mm x 130 mm x 2 mm, preheated at 180°C for about 5 minutes, pressed under a compressive load of 20 MPa for 3 minutes, and quenched at room temperature to prepare test specimens. The prepared test specimens were prepared as test specimens in accordance with the ASTM D638, Type 4 standard, and the elongation and tensile strength were measured using an Instron universal physical property testing machine (Instron 3365) at 50 mm / min in accordance with the ASTM D638 standard.

[0131] [Table 3]

[0132] As shown in Tables 2 and 3, the resin compositions of Examples 1 to 7, which have a melt index and a domain number within the ranges defined by the present invention, maintained the elongation at the same level and were superior in tensile strength compared to Comparative Examples 1 and 3 to 5, which have a melt index and a domain number outside the ranges defined by the present invention.

[0133] Meanwhile, it was shown that the resin composition of Comparative Example 2 containing the copolymer disclosed in Patent Document 1 as a compatibilizer had a significantly increased weight average molecular weight and an increased tensile strength compared to the resin composition produced in Comparative Example 1 not containing a compatibilizer, but it was confirmed that the elongation rate was rapidly decreased compared to the resin compositions of Examples 1 to 7 containing the same amount of acrylic copolymer. This is expected to be due to the fact that not only was PBAT-g-PLA formed due to the high reactivity of the copolymer serving as the compatibilizer in the resin composition of Comparative Example 2, but the copolymer serving as the compatibilizer also acted as a chain extender for each resin, forming a large amount of PBAT-g-PBAT and / or PLA-g-PLA, thereby rapidly increasing the molecular weight.

[0134] It can also be seen that the weight average molecular weights of the resin compositions of Examples 1 to 7 were increased compared to Comparative Example 1. This is because the acrylic copolymer, which is a compatibilizer, induced chemical bonds at the interface between polybutylene adipate terephthalate and polylactic acid, and also functioned as a chain extender.

[0135] On the other hand, it can be seen that the weight average molecular weight of the resin compositions of Comparative Examples 3 to 5 did not increase or increased only slightly compared to Comparative Example 1. This indicates that even if an acrylic copolymer as a compatibilizer is used, the effect of increasing the molecular weight is not observed if the melt index and the number of domains of the resin composition cannot be adjusted within the ranges limited by the present invention.

[0136] From these results, it was confirmed that the compatibility between different types of biodegradable resins is improved, the mechanical properties are improved, and an increase in the viscosity of the resin composition is prevented, resulting in excellent processability.

Claims

1. Contains a continuous phase and a dispersed phase, the continuous phase comprises a first biodegradable resin; the dispersed phase comprises a second biodegradable resin; The melt index measured in accordance with ISO 1133 at 190° C. under a load of 5 kg is 3.0 g / 10 min or more and 13.5 g / 10 min or less; A resin composition, in which the number of domains of the dispersed phase observed in an image taken at 25,000 magnification using a transmission electron microscope (TEM) is 35 or more.

2. The resin composition according to claim 1 , wherein the first biodegradable resin comprises an aliphatic polyester unit and an aromatic polyester unit.

3. The resin composition of claim 1 , wherein the first biodegradable resin comprises polybutylene adipate terephthalate.

4. The resin composition according to claim 1 , wherein the second biodegradable resin comprises polylactic acid.

5. The resin composition contains the first biodegradable resin in an amount of 50 parts by weight or more and 90 parts by weight or less, and the second biodegradable resin in an amount of 10 parts by weight or more and 50 parts by weight or less, relative to a total of 100 parts by weight of the first biodegradable resin and the second biodegradable resin. The resin composition according to claim 1.

6. 2. The resin composition according to claim 1, wherein the resin composition has a melt index measured in accordance with ISO 1133 at 190° C. under a load of 5 kg of 4.5 g / 10 min or more and 12.0 g / 10 min or less.

7. 2. The resin composition according to claim 1, wherein the size of the domains of the dispersed phase is 700 nm or less as observed in an image taken at 25,000 magnification using a transmission electron microscope (TEM).

8. The resin composition according to claim 1, wherein the resin composition has a melting enthalpy (ΔHm) of 0.01 J / g or more and 3.6 J / g or less, as measured using a differential scanning calorimeter (DSC) by adding 8 mg (error range 1 mg) of a sample, primarily heating the sample to 180° C. at a heating rate of 10° C. / min under a nitrogen flow, cooling the sample to −50° C. at a lowering rate of 10° C. / min, and then secondary heating the sample to 180° C. at a heating rate of 10° C. / min.

9. The resin composition according to claim 1 , wherein the weight average molecular weight of the entire resin composition is 137,000 or more and 200,000 or less.

10. The resin composition has a tensile strength of 245 kgf / cm when measured at a tensile speed of 50 mm / min according to ASTM D638. ２ More than 500kgf / cm ２ The resin composition according to claim 1, wherein:

11. The resin composition according to claim 1 , further comprising at least one of an acrylic copolymer and a compatibilizing part formed from the acrylic copolymer.

12. The resin composition according to claim 11, wherein the acrylic copolymer comprises a methyl (meth)acrylate monomer unit, a (meth)acrylate monomer unit containing an epoxy group, and an alkyl (meth)acrylate monomer unit having 2 to 10 carbon atoms.

13. The resin composition according to claim 11, wherein the acrylic copolymer contains 25% by weight or more and 65% by weight or less of methyl (meth)acrylate monomer units, 15% by weight or more and 60% by weight or less of (meth)acrylate monomer units containing an epoxy group, and 5% by weight or more and 32% by weight or less of alkyl (meth)acrylate monomer units having 2 to 10 carbon atoms.

14. The resin composition contains the acrylic copolymer and the compatibilizing part derived from the acrylic copolymer in an amount of 0.01 parts by weight or more and 10.0 parts by weight or less per 100 parts by weight of the first biodegradable resin and the second biodegradable resin. The resin composition according to claim 11.

15. The resin composition according to claim 11, wherein the acrylic copolymer has an epoxy equivalent (E.E.W.) of 200 g / eq or more and 800 g / eq or less.

16. The resin composition according to claim 11, wherein the acrylic copolymer has a weight average molecular weight of 10,000 or more and 100,000 or less.

17. The resin composition according to claim 11, wherein the acrylic copolymer has a glass transition temperature of 45° C. or more and 85° C. or less.

18. A molded article molded from the resin composition according to any one of claims 1 to 17.

Images