Resin composition and biodegradable resin molded article containing the same

Abstract

The present invention relates to a resin composition and a biodegradable resin molded article containing the same. The resin composition of the present invention can maintain the biodegradability inherent to polybutylene adipate terephthalate and polylactic acid, and can achieve excellent mechanical properties.

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a biodegradable resin molded article containing the same. [Background technology]

[0002] Thermoplastic polymer resins have excellent mechanical and chemical properties and are used in a variety of fields, including drinking water containers, medical applications, food packaging paper, food containers, automotive moldings, and agricultural vinyl.

[0003] Thermoplastic polymer resins, especially polyethylene film, have excellent mechanical properties and are harmless to the human body. They can be continuously deformed when heated, and are therefore widely used in hot sealing bags for food packaging and agricultural mulching films.

[0004] Hot sealing bags for food packaging are often used for vacuum packaging food products, and polyethylene film is often used because it can achieve excellent bonding strength even at low sealing temperatures.

[0005] Agricultural films are often used in mulching farming. Mulching is a material used to cover the soil surface when cultivating crops. Covering the top surface of the soil with various types of materials can block the growth of weeds and prevent the occurrence of pests and diseases, thereby reducing the use of pesticides. It also facilitates the regulation of soil temperature, promotes the growth of beneficial bacteria in the soil, prevents soil erosion, and maintains soil moisture.

[0006] Examples of such mulching materials include rice straw, leaves of crops such as grass, and polyolefin films, with synthetic resins such as polyethylene films being commonly used.

[0007] However, as mentioned above, polyethylene film, which is often used in hot sealing bags for food packaging and mulching materials, does not decompose in the natural environment, and there are limits to its reusability.In particular, it has recently become known that discarded plastics such as polyethylene film flow into the ocean and are broken down into very small microplastics by the ocean currents and sunlight.

[0008] It is now known that countless billions, or even tens of billions, of these microplastics float in the ocean, and these particles enter the bodies of marine life, accumulate in the ecosystem, and affect the entire food chain.

[0009] Therefore, there is a need to research environmentally friendly resins to replace the conventionally used thermoplastics. Summary of the Invention [Problem to be solved by the invention]

[0010] The present specification aims to provide a resin composition that is biodegradable and yet can achieve excellent mechanical properties.

[0011] The present specification also provides a biodegradable resin molded article containing the resin composition. [Means for solving the problem]

[0012] The present specification provides a resin composition comprising polybutylene adipate terephthalate; polylactic acid; and an acrylate copolymer, wherein the acrylate copolymer comprises i) a first repeating unit derived from an alkyl (meth)acrylate monomer, ii) a second repeating unit derived from an epoxy (meth)acrylate monomer, and iii) a third repeating unit derived from an alkylene glycol (meth)acrylate monomer.

[0013] According to one embodiment of the present invention, the resin composition may contain about 1 to about 50 parts by weight of polylactic acid based on 100 parts by weight of polybutylene adipate terephthalate.

[0014] According to an embodiment of the present invention, the resin composition may contain 0.1 to 10 parts by weight of an acrylate copolymer based on 100 parts by weight of polybutylene adipate terephthalate.

[0015] According to one embodiment of the present invention, the alkyl(meth)acrylate monomer may include at least one selected from the group consisting of methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, dodecyl(meth)acrylate, isobornyl(meth)acrylate, and lauryl(meth)acrylate.

[0016] According to an embodiment of the present invention, the epoxy (meth)acrylate monomer may be a compound represented by the following Chemical Formula 1: [ka]

[0017] In the above Chemical Formula 1, R1 is hydrogen or methyl, R2 is a single bond, methylene, or oxyalkylene having 1 to 3 carbon atoms, and n is 1 to 10.

[0018] According to an embodiment of the present invention, the alkylene glycol (meth)acrylate monomer may be a compound represented by the following Chemical Formula 2: [ka]

[0019] In the above chemical formula 2, R3 is hydrogen or methyl, R4 is alkylene having 1 to 3 carbon atoms, R5 is hydrogen, alkyl having 1 to 3 carbon atoms, or oxyalkyl having 1 to 3 carbon atoms, and n is 1 to 10.

[0020] According to one embodiment of the present invention, the acrylate copolymer may have an epoxy equivalent of about 400 to about 600 g / eq.

[0021] According to one embodiment of the present invention, the acrylate copolymer may have a weight average molecular weight of about 10,000 to about 50,000.

[0022] According to one embodiment of the present invention, the acrylate copolymer may have a glass transition temperature of about 60 to about 90°C.

[0023] According to an embodiment of the present invention, the resin composition may have a weight average molecular weight of 100,000 to 200,000.

[0024] According to one embodiment of the present invention, the resin composition may have a melt volume flow rate (190°C, 5 kg) measured according to ASTM D1238 conditions of about 2 to about 10 ml / 10 min.

[0025] According to one embodiment of the present invention, the resin composition has a tensile strength of about 250 to about 390 kgf / cm as measured according to ASTM D638 standard. 2 may be.

[0026] According to one embodiment of the present invention, the resin composition may have an elongation value of about 400% or more as measured according to ASTM D638 standard.

[0027] According to one embodiment of the present invention, the resin composition may have an average domain diameter of polylactic acid of 1 μm or less.

[0028] On the other hand, the present specification provides a biodegradable resin molded article containing the resin composition.

[0029] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention.

[0030] The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0031] In this specification, the terms "comprises," "comprises," or "having" are intended to describe one or more features, numbers, steps, components, or combinations thereof that may be implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations thereof, or additional features.

[0032] Also, in this specification, when a layer or element is referred to as being formed "on" or "on" another layer or element, it means that the layer or element is formed directly on the layer or element, or that other layers or elements may be additionally formed between layers, on the object, or on the substrate.

[0033] Although the present invention can be modified in various ways and can have various forms, specific examples are exemplified and described in detail below, but it should be understood that this is not intended to limit the present invention to the particular disclosed forms, and that the present invention includes all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0034] The present invention will be described in detail below.

[0035] The inventors of the present invention discovered that when specific components are used together in a blended resin obtained by blending polybutylene adipate terephthalate and polylactic acid (PLA), the compatibility between polybutylene adipate terephthalate and polylactic acid is improved, resulting in a resin composition that achieves excellent mechanical properties such as elongation and tensile strength while maintaining its inherent biodegradability, and thus completed the present invention.

[0036] A resin composition according to one aspect of the present invention comprises polybutylene adipate terephthalate; polylactic acid; and an acrylate copolymer, wherein the acrylate copolymer comprises i) a first repeating unit derived from an alkyl (meth)acrylate monomer, ii) a second repeating unit derived from an epoxy (meth)acrylate monomer, and iii) a third repeating unit derived from an alkylene glycol (meth)acrylate monomer.

[0037] The resin composition may contain about 1 to about 50 parts by weight of polylactic acid per 100 parts by weight of polybutylene adipate terephthalate, and may contain about 1 part by weight or more, or about 5 parts by weight or more, or about 10 parts by weight or more, or about 15 parts by weight or more, or about 50 parts by weight or less, or about 45 parts by weight or less, or about 40 parts by weight or less, or about 35 parts by weight or less, or about 30 parts by weight or less, or about 25 parts by weight or less.

[0038] In the resin composition, the weight ratio of polybutylene adipate terephthalate to polylactic acid may be about 6.5:3.5 or more, or about 6.9:3.1 or more, or about 7.5:2.5 or more.

[0039] In the resin composition, the weight ratio of polybutylene adipate terephthalate to polylactic acid may be about 9.5:0.5 or less, or about 9.1:0.9 or less.

[0040] If the content of polylactic acid is too low, the effect of improving the mechanical properties of PBAT may not be achieved, and if the content of polylactic acid is too high, problems may arise such that the hardness increases and the elongation of the resin composition decreases. In particular, when the resin composition is processed into a biodegradable film, etc., problems may arise such that the processability decreases and the mechanical properties of the resin composition decrease.

[0041] Polyester resins have excellent mechanical and chemical properties and are used in a variety of industrial fields. Among them, polybutylene adipate terephthalate (PBAT) is a soft polyester that is biodegradable and is therefore attracting attention as a substitute for polyolefin polymers, which are mainly used in food packaging and agricultural films.

[0042] However, depending on the application, soft polybutylene adipate terephthalate may not have sufficient mechanical properties to be used alone, so it is often blended with hard polylactic acid (PLA) or compounded with an organic filler such as carbon black.

[0043] However, since polybutylene adipate terephthalate and polylactic acid have very low compatibility, a compatibilizer must be used when blending these two to produce a blended resin.

[0044] Therefore, a resin composition according to one aspect of the present invention contains, as a compatibilizer component, an acrylate copolymer in which a specific component monomer is copolymerized.

[0045] The acrylate copolymer according to one embodiment of the present invention can increase the flexibility of the polymer chain due to its molecular structural characteristics, and can enhance the compatibility of PBAT and PLA. When a film is produced using such a composition, it can increase chain diffusion and entanglement at the film interface.

[0046] As a result, the resin composition according to one aspect of the present invention has excellent processability and can achieve very high mechanical properties while maintaining the biodegradability inherent to PBAT and PLA.

[0047] The resin composition may contain about 0.1 to about 10 parts by weight of the acrylate copolymer per 100 parts by weight of polybutylene adipate terephthalate, and may contain about 0.1 part by weight or more, or about 0.2 parts by weight or more, or about 0.3 parts by weight or more, or about 0.4 parts by weight or more, or about 10 parts by weight or less, or about 8 parts by weight or less, or about 7 parts by weight or less, or about 6 parts by weight or less, or about 5 parts by weight or less. The acrylate copolymer includes i) a first repeating unit derived from an alkyl(meth)acrylate monomer, ii) a second repeating unit derived from an epoxy(meth)acrylate monomer, and iii) a third repeating unit derived from an alkylene glycol(meth)acrylate monomer.

[0048] The acrylate copolymer may be in the form of a resin copolymer formed by polymerizing monomers or an emulsion in which latex particles are dispersed, and each of the monomers may exist in the copolymer in the form of a repeating unit derived from that monomer.

[0049] Monomer First, an alkyl (meth)acrylate monomer is used in the polymerization for producing the latex particles, which can be referred to as a first monomer. Thus, the latex particles can include a repeating unit derived from the alkyl (meth)acrylate monomer, which can be referred to as a first repeating unit.

[0050] Copolymers containing the first repeating unit have excellent compatibility with polylactic acid. For example, in a blended resin made by mixing polymethyl(meth)acrylate, which is a homopolymer of methyl(meth)acrylate, with polylactic acid, the glass transition temperature measurement value shows a single value, indicating that polyalkyl(meth)acrylate and polylactic acid are highly compatible with each other.

[0051] Furthermore, the copolymer containing the first repeating unit exhibits better affinity with polybutylene adipate terephthalate than with polylactic acid, and thus has excellent compatibility with polylactic acid and relatively excellent affinity with polybutylene adipate terephthalate, making it suitable for use as a compatibilizer.

[0052] According to one embodiment of the present invention, the alkyl(meth)acrylate monomer may include at least one selected from the group consisting of methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, dodecyl(meth)acrylate, isobornyl(meth)acrylate, and lauryl(meth)acrylate.

[0053] In addition, an epoxy (meth)acrylate monomer is further used in the polymerization for producing the latex particles, which can be referred to as a second monomer. Thus, the latex particles can include a repeating unit derived from the epoxy (meth)acrylate monomer, which can be referred to as a second repeating unit.

[0054] According to one embodiment of the present invention, the epoxy (meth)acrylate monomer may be a compound represented by the following Chemical Formula 1: [ka]

[0055] In the above Chemical Formula 1, R1 is hydrogen or methyl, R2 is a single bond, methylene, or oxyalkylene having 1 to 3 carbon atoms, and n is 1 to 10.

[0056] In copolymers containing the second repeating unit, the epoxy group can interact with the hydroxyl group (-OH) or carboxyl group (-COOH) contained in polybutylene adipate terephthalate or polylactic acid.

[0057] Therefore, the copolymer containing the second repeating unit can react with the terminals of polybutylene adipate terephthalate or polylactic acid to increase the molecular weight, and if this reaction occurs at the interface between polybutylene adipate terephthalate and polylactic acid, it can improve the compatibility and interfacial adhesion between the two.

[0058] In addition, an alkylene glycol (meth)acrylate monomer is further used in the polymerization for producing the latex particles, which can be referred to as a third monomer. Thus, the latex particles can include a repeating unit derived from the alkylene glycol (meth)acrylate monomer, which can be referred to as a third repeating unit.

[0059] According to one embodiment of the present invention, the alkylene glycol (meth)acrylate monomer may be a compound represented by the following Chemical Formula 2: [ka]

[0060] In the above chemical formula 2, R3 is hydrogen or methyl, R4 is alkylene having 1 to 3 carbon atoms, R5 is hydrogen, alkyl having 1 to 3 carbon atoms, or oxyalkyl having 1 to 3 carbon atoms, and n is 1 to 10.

[0061] The third monomer contains an alkylene glycol repeating unit in its molecule, which can impart hydrophilicity to the copolymer. As a result, the copolymer containing the third monomer can have excellent miscibility with polybutylene adipate terephthalate and polylactic acid.

[0062] The acrylate copolymer may contain about 30 to about 60% by weight of the first repeating unit, about 30 to about 60% by weight of the second repeating unit, and about 5 to about 30% by weight of the third repeating unit, or about 40 to about 50% by weight of the first repeating unit, about 35 to about 45% by weight of the second repeating unit, and about 10 to about 20% by weight of the third repeating unit.

[0063] If the content exceeds the above range or if other monomers are used, the affinity and compatibility of the resulting copolymer with polybutylene terephthalate adipate and polylactic acid may decrease, which may result in a decrease in the interfacial adhesion between the components in a blended resin of polybutylene terephthalate adipate and polylactic acid, resulting in a decrease in compatibility.

[0064] The acrylate copolymer contained in the composition according to one example of the present invention can be produced by a polymerization method such as radical polymerization, emulsion polymerization, or bulk polymerization.

[0065] For example, the acrylate copolymer contained in the composition according to one example of the present invention can be produced by an emulsion polymerization method including a step of emulsion polymerizing a polymerization composition containing a monomer mixture containing the above-mentioned first monomer, second monomer, and third monomer; a polymerization initiator; and an emulsifier.

[0066] At this time, the polymerization temperature and polymerization time can be appropriately determined depending on the case. For example, the polymerization temperature may be about 50° C. to about 200° C., and the polymerization time may be about 0.5 hours to about 20 hours.

[0067] The polymerization initiator usable in the emulsion polymerization may be an inorganic or organic peroxide. For example, water-soluble polymerization initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate, and oil-soluble polymerization initiators such as cumene hydroperoxide and benzoyl peroxide may be used.

[0068] In addition, an activator may be used together with the polymerization initiator to promote the initiation of the peroxide reaction. As such an activator, one or more selected from the group consisting of sodium formaldehyde sulfoxylate, sodium ethylenediaminetetraacetate, ferrous sulfate, and textrose may be used.

[0069] The polymerization initiator is contained in an amount of about 0.1 to about 10 parts by weight, preferably about 0.1 to about 5 parts by weight, based on 100 parts by weight of the monomer mixture on a dry weight basis.

[0070] Also, a chain transfer agent (or chain transfer agent) can be used in combination to increase the efficiency of the polymerization reaction.

[0071] The chain transfer agent can function to incorporate a homopolymer, which is a polymer composed of only one type of monomer, into micelles during the polymerization process.

[0072] Such a chain transfer agent can be a linear or branched alkylthiol compound having 5 to 20 carbon atoms. Specific examples of the alkylthiol compound include hexanethiol, cyclohexanethiol, adamantanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, todecanethiol, hexadecanethiol, and octadecanethiol.

[0073] Such a chain transfer agent is contained in an amount of about 0.1 to about 10 parts by weight, preferably about 0.1 to about 5 parts by weight, based on 100 parts by weight of the monomer mixture on a dry weight basis.

[0074] Specifically, the emulsion polymerization can be carried out by the following steps.

[0075] The first step is to disperse an emulsifier in a solvent to produce an emulsion; A second step of mixing a monomer mixture containing each monomer component and an emulsifier to produce a pre-emulsion; The third step is to mix the emulsion from the first step and the pre-emulsion from the second step in the presence of a polymerization initiator to allow emulsion polymerization to proceed.

[0076] In a specific embodiment of the present invention, the above-mentioned acrylate copolymer is specifically prepared by the following method, but is not necessarily limited thereto.

[0077] The first step is to prepare an emulsion containing an emulsifier. This is separate from the pre-emulsion preparation process described below. The emulsifier can be an anionic emulsifier alone, or a combination of an anionic emulsifier, a cationic emulsifier, and a non-ionic emulsifier. The emulsion can be prepared by mixing these emulsifier components with a solvent such as water.

[0078] During the emulsion preparation process, primary micelle particles of several nanometers in size are stably formed.

[0079] Then, in the second step, in the process of producing a pre-emulsion containing the above-mentioned monomer mixture, the above-mentioned monomers, emulsifier, etc. are mixed with water to produce the pre-emulsion.

[0080] In this case, an anionic emulsifier can be used alone or in combination with the above-mentioned nonionic emulsifier. During this process, nano-sized latex particles are formed in the pre-emulsion.

[0081] That is, the above-mentioned emulsifier can be used in at least one of the steps of preparing an emulsion and the step of preparing a pre-emulsion.

[0082] Then, in the third step, a polymerization initiator is added to the emulsion prepared above, and then the pre-emulsion and the polymerization initiator are continuously added in equal proportions for a predetermined period of time.

[0083] In a non-limiting embodiment of the present invention, the content of the polymerization initiator added to the emulsion may be about 0 to about 1 part by weight based on 100 parts by weight of the monomer mixture, the content of the polymerization initiator added together with the pre-emulsion may be about 0.1 to about 2 parts by weight based on 100 parts by weight of the monomer mixture, and the continuous addition time may be about 3 to about 7 hours.

[0084] Through this process, the monomers or polymers suspended in the emulsion can flow into the primary particles formed in the emulsion.

[0085] The reaction product may then be subjected to a thermal polymerization process in the presence of an additional polymerization initiator, thereby polymerizing the remaining monomers.

[0086] In this case, the polymerization initiator may be further added in an amount of about 0.1 to about 10 parts by weight based on 100 parts by weight of the monomer mixture, and the thermal polymerization may proceed at a temperature of about 75 to about 85°C for about 40 to about 80 minutes.

[0087] Such emulsion polymerization method is divided into an emulsion production process and a pre-emulsion production process, and can proceed in a simple manner of subsequently mixing the pre-emulsion with the emulsion, thereby improving process stability and productivity compared to conventional methods.

[0088] emulsifier 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.

[0089] These emulsifiers are substances that have both hydrophilic and hydrophobic groups, and form a micelle structure during emulsion polymerization, allowing the polymerization of each monomer to occur within the micelle structure.

[0090] Emulsifiers commonly used in emulsion polymerization can be divided into anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, etc., but two or more of them can also be used in combination in terms of polymerization stability in emulsion polymerization.

[0091] Specifically, the nonionic emulsifier may include one or more selected from the group consisting of polyethylene oxide alkyl aryl ether, polyethylene oxide alkyl amine, and polyethylene oxide alkyl ester.

[0092] The anionic emulsifier may include at least one selected from the group consisting of sodium alkyl diphenyl ether disulfonate, sodium polyoxyethylene alkyl ether sulfonate, sodium polyoxyethylene aryl ether sulfonate, sodium alkyl sulfonate, sodium alkyl benzene sulfonate, and dialkyl sodium sulfosuccinate.

[0093] These can be used alone or in combination of two or more. A mixture of an anionic emulsifier and a nonionic emulsifier is more effective, but the present invention is not necessarily limited to such types of emulsifiers.

[0094] The emulsifier can be used in an amount of, for example, about 0.1 to about 10 parts by weight, or about 1 to about 5 parts by weight, relative to 100 parts by weight of the total monomer components used in producing the latex particles.

[0095] If the amount of emulsifier used is too large, the particle size of the latex particles may become small, which may cause a problem of reduced adhesive strength. If the amount of emulsifier used is too small, the stability of the polymerization may decrease in the emulsion polymerization reaction, which may cause a problem of reduced stability of the resulting latex particles.

[0096] solvent According to an embodiment of the present invention, the polymerization composition may further contain an aqueous solvent such as water in addition to the above-mentioned emulsifier and monomer components. In this regard, 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 stability and viscosity control of the latex particles. For example, the aqueous solvent may be used so that the total solid content (TSC) is adjusted to about 10 to about 60 wt% based on the total weight of the composition.

[0097] The acrylate copolymer may have an epoxy equivalent of about 400 to about 600 g / eq, or about 400 g / eq or more, or about 450 g / eq or more, or about 500 g / eq or more, and about 600 g / eq or less, or about 550 g / eq or less, or about 520 g / eq or less.

[0098] If the epoxy equivalent value is too low, the reactivity with the aforementioned polybutylene adipate terephthalate or polylactic acid terminals may be low, which may result in a problem of reduced interfacial adhesion at the interface of each component of the blending resin. Conversely, if the epoxy equivalent value is too high, the reactivity may be too high, which may induce an excessive increase in the viscosity of the blending resin, which may result in a problem of reduced processability of the blending resin.

[0099] The acrylate copolymer may have a weight average molecular weight of about 10,000 to about 50,000, or about 10,000 or more, or about 12,000 or more, or about 13,000 or more, and may be about 50,000 or less, or about 40,000 or less, or about 35,000 or less.

[0100] If the weight average molecular weight of the acrylate copolymer is too high or too low, the compatibility with polybutylene adipate terephthalate and polylactic acid may decrease, which may result in a problem of reduced inherent physical properties of the blended resin.

[0101] The acrylate copolymer may have a glass transition temperature of about 60 to about 90°C, or about 60°C or higher, or about 70°C or higher, or about 80°C or higher, and about 90°C or lower, or about 85°C or lower.

[0102] The acrylate copolymer may have a molecular weight increase rate relative to polybutylene adipate terephthalate and polylactic acid of more than about 0% to about 30%, or more than about 0%, or about 2% or more, or about 5% or more, or about 30% or less, or about 25% or less, or about 20% or less.

[0103] The acrylate copolymer can function as a compatibilizer to enhance the compatibility of polybutylene adipate terephthalate and polylactic acid, as well as a molecular weight modifier to increase the molecular weight of the polymer resin.

[0104] Here, the molecular weight increase rate refers to the rate at which the weight average molecular weight of the polybutylene adipate terephthalate and polylactic acid blending resin increases when an acrylate copolymer is used or after an acrylate copolymer is added, compared to the weight average molecular weight of the polybutylene adipate terephthalate and polylactic acid blending resin when an acrylate copolymer is not used or before an acrylate copolymer is added, based on the weight average molecular weight of a blending resin composition containing the same type and content of polybutylene adipate terephthalate and polylactic acid.

[0105] According to one embodiment of the invention, the resin composition may have a weight average molecular weight of 100,000 to 200,000, or about 100,000 or more, or about 110,000 or more, or about 120,000 or more, or about 130,000 or more, or about 140,000 or more, and about 200,000 or less, or about 190,000 or less, or about 180,000 or less, or about 170,000 or less, or about 160,000 or less.

[0106] In addition, the resin composition according to an embodiment of the present invention may further contain other additives. The additives may be any additives commonly used in molding resin compositions in the technical field to which the present invention pertains, i.e., in the field of thermoplastic polymers, without any particular limitations.

[0107] Additives can include heat stabilizers, UV stabilizers, and the like.

[0108] The additive may be contained in an amount of about 1 to about 30 parts by weight relative to 100 parts by weight of the polybutylene adipate terephthalate and polylactic acid in total.

[0109] The resin composition can contain about 1 to about 50 parts by weight, or about 10 to about 30 parts by weight, or about 15 to about 25 parts by weight of an inorganic filler relative to 100 parts by weight in total of the polybutylene adipate terephthalate and polylactic acid.

[0110] The inorganic filler can improve the mechanical properties and processability of the resin composition. If the inorganic filler is contained in an excessively small amount, the above-mentioned advantageous effects may not be achieved, whereas if the inorganic filler is contained in an excessively large amount, the mechanical properties and processability of the resin composition may be deteriorated.

[0111] The resin composition may have a melt volume flow rate (190°C, 5 kg) measured in accordance with ASTM D1238 conditions of 2 to 10 ml / 10 min, or about 2 ml / 10 min or more, or about 2 ml / 10 min or more, or about 2 ml / 10 min or more, or about 2 ml / 10 min or more, or about 2 ml / 10 min or more, and about 10 ml / 10 min or less, or about 9 ml / 10 min or less, or about 8 ml / 10 min or less, or about 7 ml / 10 min or less.

[0112] The resin composition has a tensile strength of about 250 to about 390 kgf / cm as measured in accordance with ASTM D638 standard. 2 , or approximately 250 kgf / cm 2 or more, or approximately 300 kgf / cm 2 or more, or approximately 320 kgf / cm 2 or more, approximately 390 kgf / cm 2 or less, or approximately 370 kgf / cm 2 or less, or approximately 360 kgf / cm 2 It may be the following:

[0113] If the tensile strength value is too low, problems may occur in the mechanical properties such as film strength during film production, while if the tensile strength value is too high, problems may occur in the stretching process during film production, making it difficult to use as a mulching film, etc.

[0114] The resin composition may have an elongation value, measured according to ASTM D638 standard, of 400% or more, or about 450% or more, or about 500% or more, or about 550% or more, or about 600% or more, and may have an elongation value of about 1000% or less, or about 900% or less, or about 800% or less, or about 700% or less.

[0115] If the elongation value is too low, stretching processing during film production may be difficult, which may make it difficult to use as a mulching film or the like.

[0116] In the resin composition, the average domain diameter of the polylactic acid may be about 1 μm or less, or about 800 nm or less, or about 500 nm or less.

[0117] Polybutylene adipate terephthalate and polylactic acid are not completely miscible with each other and therefore exist in separate states within the blending resin. Generally, polylactic acid exists in a dispersed form with certain independent regions, i.e., domains, within the polybutylene adipate terephthalate matrix.

[0118] Here, the domain diameter refers to the diameter of a circular domain that appears when observing the surface or cross section of a resin composition containing spherical polylactic acid domains formed in a polybutylene adipate terephthalate matrix. If the observed domain shape is not circular, the domain diameter refers to the longest straight line passing through the center point of the domain, i.e., the longest diameter.

[0119] The average domain diameter means the number average value of the above-mentioned domain diameter values.

[0120] Such an average domain diameter value can be measured and confirmed by analyzing an image of the resin composition obtained by SEM or the like using an image analysis program or the like.

[0121] Specifically, the average domain diameter of the polylactic acid in the resin composition may be about 1 μm or less, or about 800 nm or less, or about 500 nm or less.

[0122] In a resin composition according to an embodiment of the present invention, due to the high compatibility between polybutylene adipate terephthalate and polylactic acid, the domain size of the polylactic acid dispersed within the polybutylene adipate terephthalate matrix is ​​very small, allowing the polylactic acid to be uniformly dispersed within the polybutylene adipate terephthalate.

[0123] The present specification also provides a biodegradable resin molded article containing the above-mentioned resin composition.

[0124] The biodegradable resin molded article according to one aspect of the present invention may be a biodegradable film.

[0125] Due to such excellent mechanical properties, the biodegradable resin molded article according to one embodiment of the present invention can be used for applications such as agricultural mulching films and food packaging materials. [Effects of the Invention]

[0126] The resin composition of the present invention can maintain the biodegradability inherent to polybutylene adipate terephthalate and polylactic acid, and can achieve excellent mechanical properties. DETAILED DESCRIPTION OF THE INVENTION

[0127] The functions and effects of the present invention will be described in more detail below with reference to specific examples of the present invention, however, these examples are merely examples of the present invention and do not define the scope of the present invention.

[0128] Production of acrylate copolymers As the acrylate copolymer in Comparative Example 1, Joncryl ADR-4368 (manufacturer: basf) was used.

[0129] Examples and Comparative Examples A 3 L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube, and a reflux condenser was charged with 100 parts by weight of the total amount of monomers listed below, 200 parts by weight of distilled water, and 0.5 parts by weight of dioctyl sulfosuccinate sodium (bis(2-ethylhexyl) sulfosuccinate sodium) as an emulsifier component, and stirred. After the inside of the reactor was purged 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 30 minutes.

[0130] Separately, the monomers listed in the table below were placed in a beaker and thoroughly mixed for 30 minutes. 1-octanethiol was added as a chain transfer agent in an amount of 0.5 parts by weight per 100 parts by weight of the total monomers. After thorough mixing with a stirrer, the mixture was continuously and evenly added to the glass reactor for 6 hours.

[0131] After 6 hours of polymerization reaction, the temperature inside the glass reactor was maintained at 70° C. for 30 minutes, and then cooled to room temperature.

[0132] The resulting emulsion polymerization product was coagulated using an aqueous calcium acetate solution, heat-treated at a temperature of about 85°C, dehydrated, and dried at about 60°C for about 16 hours to obtain an acrylate copolymer. [Table 1] MMA: methyl methacrylate; GMA: glycidyl methacrylate; BA: butyl acrylate; PEGMA: polyethylene glycol methacrylate (number of ethylene glycol repeating units: 6)

[0133] Molecular weight measurement The obtained acrylate copolymer sample was measured using gel permeation chromatography (GPC, PL GPC220, Agilent Technologies) under the following conditions: The sample was dissolved in tetrahydrofuran (stabilized with BHT) at a concentration of 2 mg / ml, and a portion of the solution was taken to measure the weight-average molecular weight and number-average molecular weight.

[0134] -Column: PL MiniMixed B x 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 standard (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)

[0135] Epoxy equivalent measurement The content ratio (molar ratio) of glycidyl acrylate was measured by nuclear magnetic resonance spectroscopy using a Bruker 700MHz NMR spectrometer, from which the number of equivalents of epoxy groups (eq / mol) was determined, and the epoxy equivalent (eq / g) was calculated using the number average molecular weight (Mn) value measured above.

[0136] average particle diameter The obtained acrylate copolymers were each diluted with distilled water to a concentration of 200 ppm, and the average particle diameter (D50) was measured using a NICOMP 380 according to the dynamic light scattering (DLS) method of ISO 22412.

[0137] The measurement results are summarized in the table below. [Table 2]

[0138] Referring to Table 1, it can be seen that the copolymer according to one embodiment of the present invention has a relatively high epoxy equivalent value and a very high glass transition temperature value compared to the comparative example.

[0139] Production of resin compositions The polybutylene adipate terephthalate used was TH801T product from Xinjiang Blueridge Tunhe Chemical Industry Co., Ltd.

[0140] As the polylactic acid, Natureworks' Ingeo Biopolymer 2003D product was prepared.

[0141] The polybutylene adipate terephthalate and polylactic acid prepared above were dried in an oven at 60° C. for about 24 hours before use.

[0142] 80 parts by weight of polybutylene adipate terephthalate, 20 parts by weight of polylactic acid, and 1 part by weight of the acrylate copolymer produced above were mixed and blended for about 10 minutes at 170°C and about 60 rpm using a Haake Rheomix OS Lab mixer from Thermo Electron Karlsruhe GmbH, and then pulverized to obtain a resin composition.

[0143] Elongation and tensile strength measurements The resin composition obtained above was placed in a 125×125×2 mm mold, preheated at 180° C. for about 5 minutes, pressed under a compressive load of 10 MPa for 3 minutes, and then quenched at room temperature to prepare a test piece.

[0144] The specimens prepared as above were prepared as test specimens according to ASTM D638, Type 4 standard.

[0145] The prepared test specimens were measured for elongation and tensile strength using an Instron universal physical property tester at 50 mm / min according to ASTM D638 standard.

[0146] Workability evaluation When gelation did not occur during the processing of the resin composition and no separation of the resin components occurred, the resin composition was evaluated as ◯, and when gelation occurred or phase separation of the resin components occurred, the resin composition was evaluated as ×.

[0147] Molecular weight and molecular weight distribution measurement The obtained composition was measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies) under the following conditions. At this time, the sample was dissolved in Chloroform solvent at a concentration of 1 mg / ml, and a portion of the solution was taken to measure the molecular weight. -Column: PL MiniMixed Bx2 -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: 9 types: 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000)

[0148] MFR value measurement The resin composition samples obtained above were measured according to ASTM D1238 conditions (190°C, 5 kg) using a Gottfert MI-4. The measurement results are summarized in the table below. [Table 3]

[0149] From the table, it can be seen that in the case of Comparative Example 5, which does not use an acrylate copolymer, the molecular weight is low and the tensile strength value is very low.

[0150] In the cases of Comparative Examples 3 and 4, the molecular weight was increased to some extent, but problems arose such as gelation of the resin composition during processing, resulting in reduced processability. Also, in the cases of Comparative Examples 3 and 4, the tensile strength was too high, which is thought to result in reduced processability when processed into mulching film, etc.

[0151] In the case of Comparative Example 2, the molecular weight increase rate was about 107%, and it was confirmed that there was almost no effect in increasing the molecular weight, and there were problems with gelation occurring in some parts and phase separation of the resin components occurring in some parts during processing of the resin composition. In the case of Comparative Example 2, it is thought that there are problems with commercializing polybutylene adipate terephthalate and polylactic acid.

[0152] In the case of Comparative Example 1, which used Joncryl, the molecular weight increase was about 130%, and it appears that the commercialization of polybutylene adipate terephthalate and polylactic acid is proceeding smoothly. However, the MFR is 0, and the viscosity is very high even at high temperatures, which is expected to make processing, such as molding, of the resin composition very difficult.

[0153] On the other hand, it was revealed that the resin composition according to one example of the present invention effectively increased the molecular weight of the resin composition, even though the epoxy equivalent weight per molecule was lower compared to Comparative Example 2, etc. This is thought to be because the PEGMA segment of the copolymer has high compatibility with polybutylene adipate terephthalate or polylactic acid.

[0154] As a result, the resin composition according to the embodiment of the present invention can achieve a moderate molecular weight increase rate, viscosity, tensile strength, and elongation, and is considered to be highly useful when used as a mulching film, etc.

Claims

1. Polybutylene adipate terephthalate; polylactic acid; and Contains an acrylate copolymer, The acrylate copolymer comprises: i) a first repeating unit derived from an alkyl (meth)acrylate monomer; ii) a second repeating unit derived from an epoxy (meth)acrylate monomer; and iii) a third repeating unit derived from an alkylene glycol (meth)acrylate monomer.

2. The resin composition according to claim 1, comprising 1 to 50 parts by weight of polylactic acid per 100 parts by weight of polybutylene adipate terephthalate.

3. The resin composition according to claim 1, comprising 0.1 to 10 parts by weight of an acrylate copolymer per 100 parts by weight of polybutylene adipate terephthalate.

4. The resin composition according to claim 1, wherein the alkyl (meth)acrylate monomer comprises at least one selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, and isobornyl (meth)acrylate.

5. The resin composition according to claim 1, wherein the epoxy (meth)acrylate monomer is a compound represented by the following chemical formula 1: 【Chemical 1】 In the above Chemical Formula 1, R1 is hydrogen or methyl; R2 is a single bond, methylene, or oxyalkylene having 1 to 3 carbon atoms; n is 1 to 10.

6. The resin composition according to claim 1, wherein the alkylene glycol (meth)acrylate monomer is a compound represented by the following chemical formula 2: 【Chemistry 2】 In the above Chemical Formula 2, R3 is hydrogen or methyl; R4 is alkylene having 1 to 3 carbon atoms, R5 is hydrogen, alkyl having 1 to 3 carbon atoms, or oxyalkyl having 1 to 3 carbon atoms; n is 1 to 10.

7. 2. The resin composition according to claim 1, wherein the acrylate copolymer has an epoxy equivalent of 400 to 600 g / eq.

8. 2. The resin composition according to claim 1, wherein the acrylate copolymer has a weight average molecular weight of 10,000 to 50,000.

9. 2. The resin composition according to claim 1, wherein the acrylate copolymer has a glass transition temperature of 60 to 90°C.

10. The resin composition according to claim 1, wherein the weight average molecular weight is 100,000 to 200,000.

11. 2. The resin composition according to claim 1, wherein the melt volume flow rate (190°C, 5 kg) measured in accordance with ASTM D1238 conditions is 2 to 10 ml / 10 min.

12. Tensile strength measured according to ASTM D638 standard: 250 to 390 kgf / cm ２ The resin composition according to claim 1,

13. 2. The resin composition according to claim 1, which has an elongation value of 400% or more as measured according to ASTM D638 standard.

14. 2. The resin composition according to claim 1, wherein the polylactic acid has an average domain diameter of 1 μm or less.

15. A biodegradable resin molded article comprising the resin composition according to any one of claims 1 to 14.

Images