Polybutylene adipate terephthalate resin and biodegradable film comprising same

Abstract

The present invention relates to a polybutylene adipate terephthalate resin having a controlled biodegradation rate and excellent coatability and an article comprising same.

Description

Polybutylene adipate terephthalate resin and biodegradable film containing the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0138010 filed on October 10, 2024, and all contents disclosed in the literature of said Korean patent applications are incorporated herein as part of this specification.

[0003] The present invention relates to a polybutylene adipate terephthalate resin and a biodegradable film containing the same.

[0004] Recently, issues such as human safety concerns regarding microplastics and endocrine disruptors, as well as the depletion of natural resources used as plastic raw materials, have been emerging. Significant amounts of these microplastics are known to be floating in the ocean; they enter the bodies of marine organisms, accumulate within the ecosystem, and affect the entire food chain.

[0005] Therefore, research on alternatives to existing plastics is necessary, and among them, interest is growing in polybutyleneadipate terephthalate (PBAT), a biodegradable polymer with flexible properties.

[0006] PBAT is primarily manufactured into eco-friendly consumer film or applied as a coating on the surfaces of various products, such as paper, non-woven fabrics, and fertilizers, to create environmentally friendly and biodegradable products.

[0007] However, these PBAT films or PBAT coating layers have a problem in that moisture present in the atmosphere permeates them, accelerating biodegradation even during product use. If the biodegradation rate of PBAT is excessively fast, the strength and flexibility of products coated with PBAT films or PBAT resin are reduced, and their lifespan is shortened. Furthermore, additional management of environmental factors such as temperature and humidity is required for product storage conditions, which lowers the commercial viability of the product.

[0008] One objective of the present invention is to provide a polybutylene adipate terephthalate resin having high moisture barrier properties, controlled biodegradability, and shape collapse rate.

[0009] Another objective of the present invention is to provide a film for various applications comprising the above-described polybutylene adipate terephthalate resin, wherein the film has low moisture permeability, maintains excellent physical properties during use, and is biodegradable after disposal.

[0010] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0011] According to one embodiment of the present invention, a polybutylene adipate terephthalate (PBAT) resin comprising repeating units derived from 1,4-butanediol, terephthalic acid, and adipic acid is provided, wherein the cured product of the resin has a moisture permeability (water vapor permeability) of 50 to 150 g / m² measured under conditions of 38°C and 90% relative humidity. 2 ·d, preferably 70 to 120 g / m² 2 ·d can be

[0012] The weight-average molecular weight of the resin may be 70,000 to 100,000 g / mol, and preferably 80,000 to 90,000 g / mol.

[0013] The melting enthalpy (dsc) of the above resin is 26 to 50 J / g, and preferably 28 to 40 J / g.

[0014] The above resin may have a crystallization temperature (Tc) of 50 to 115 ℃.

[0015] The above resin may have a glass transition temperature (Tg) of -28 to -10 ℃.

[0016] The above resin may have a melting temperature (Tm) of 135 to 170 ℃.

[0017] The melt index (MI) of the above resin measured at 190 ℃ under a 2.16 kg load 2.16 ) may be 25 g / 10min or more and 60 g / 10min or less.

[0018] The above resin may contain repeating units derived from terephthalic acid and repeating units derived from adipic acid in a molar ratio of 52:48 to 65:35.

[0019] According to another embodiment of the present invention, the invention relates to a biodegradable film comprising the polybutylene adipate terephthalate resin described above.

[0020] The above film may be an agricultural mulching film, a packaging film, a shrink film, or a bag film.

[0021] The film or coating layer made of the polybutylene adipate terephthalate (PBAT) resin provided in the present invention has a low moisture permeability, and the initial biodegradation rate and shape collapse rate are controlled, so that the film or coated article maintains excellent durability during use and is easy to store.

[0022] Figure 1 shows the results of evaluating the biodegradability using enzymes for the resins prepared in the examples and comparative examples in Experimental Example 2.

[0023] According to one embodiment of the present invention, a polybutylene adipate terephthalate (PBAT) resin comprising repeating units derived from 1,4-butanediol, terephthalic acid, and adipic acid is provided, wherein the cured product of the resin has a moisture permeability (water vapor permeability) of 50 to 150 g / m² measured under conditions of 38°C and 90% relative humidity. 2 ·d can be

[0024] According to another embodiment of the present invention, the invention relates to a biodegradable film comprising the polybutylene adipate terephthalate resin described above.

[0025] Unless otherwise defined in this specification, all technical and scientific terms are used merely to describe exemplary embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the presence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0026] The present invention is capable of various modifications and may take various forms, and specific embodiments are illustrated and described in detail below. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0027] The technical terms used in this specification are intended merely to refer to specific embodiments and are not intended to limit the invention. Furthermore, the singular forms used herein include plural forms unless phrases clearly indicate otherwise.

[0028] Recently, as environmental protection and the sustainable use of resources have emerged as critical global issues, various efforts are being made to address the problem of plastic waste. In particular, conventional petroleum-based plastics do not decompose naturally and accumulate in the environment over the long term, causing serious pollution issues. Consequently, biodegradable plastics are garnering attention as an alternative to reduce their environmental impact.

[0029] Among them, polybutylene adipate terephthalate (PBAT) is being widely researched and developed as an eco-friendly material due to its biodegradable properties as a polymer. PBAT satisfies both the flexibility and mechanical strength requirements of polymers while enabling natural biodegradation after disposal, making it suitable for various applications, particularly in agricultural mulching films, food packaging materials, and disposable products.

[0030] PBAT resin has the advantage of being decomposed primarily by microorganisms under aerobic conditions, ultimately breaking down completely into water and carbon dioxide. Thanks to these biodegradable properties, it is gaining attention as a material that can reduce environmental burden; however, concerns have been raised regarding the excessively rapid rate of PBAT resin's biodegradation. Although films or coating layers made from PBAT must maintain sufficient durability over their service life, if biodegradation proceeds too quickly, mechanical properties may deteriorate and functionality may be lost during use. Furthermore, there is a risk of damage to the product during storage, making storage conditions stringent and raising issues such as economic feasibility.

[0031] As a result of diligent efforts, the inventors of the present invention discovered that a polybutylene adipate terephthalate (PBAT) resin, which is biodegradable and has moisture barrier properties and satisfies the level shown below, has a controlled biodegradation rate, and that films or coated articles made of said resin maintain excellent physical properties during use and are easy to store, thereby completing the present invention.

[0032] According to one embodiment of the present invention, the invention relates to a polybutylene adipate terephthalate (PBAT) resin comprising repeating units derived from monomers 1,4-butanediol, terephthalic acid, and adipic acid, wherein the cured product of the resin has a moisture permeability of 50 to 150 g / m² measured under conditions of 38 ℃ and 90% relative humidity. 2 ·d is characterized by being less than or equal to

[0033] The above water vapor transmission rate is the water vapor transmission rate measured in the thickness direction of the film when the above-described polybutylene adipate terephthalate (PBAT) resin is manufactured in the form of a film with a thickness of 5 to 100 μm, for example, 50 μm, and can be calculated according to Equation 1 below. The above water vapor transmission rate was measured under conditions of 38°C and 90% relative humidity. A lower value of the above water vapor transmission rate indicates higher moisture barrier performance.

[0034] [Equation 1]

[0035]

[0036] In Equation 1 above, the amount of water vapor passing through refers to the amount of water vapor (g) passing through the film-shaped resin, and the area of ​​the specimen is the area of ​​the film specimen (m² 2 It means ), and the time (day) is the time the experiment was performed, and the unit is day.

[0037] Since moisture is essential for the survival of microorganisms and enzymatic activity, water vapor permeability and biodegradability are closely related. By controlling the water vapor permeability of the above-mentioned polybutylene adipate terephthalate resin, the biodegradation rate can be controlled to a desired level.

[0038] The moisture permeability of the polybutylene adipate terephthalate (PBAT) resin cured product according to the present invention, measured under the above conditions, is 150 g / m² 2 ·d or less, 140 g / m² 2 ·d or less, 130 g / m² 2 ·d or less, 120 g / m² 2 ·d or less, 110 g / m² 2 ·d or less, 105 g / m² 2 ·d or less or 100 g / m² 2 ·d may be less. The above moisture permeability is 150 g / m² 2 If ·d is exceeded, moisture permeability of the resin cured product, i.e., the film, is promoted, leading to increased microbial activity and potentially rapid biodegradation. Conversely, if moisture permeability is low, the rate of biodegradation may be slowed down.

[0039] The lower limit of the above moisture permeability is not specifically restricted, but considering biodegradability, it should be 50 g / m² 2 ·d or greater, 60 g / m² 2 ·d or greater, 70 g / m² 2 ·d or greater, 80 g / m² 2 ·d or greater, 90 g / m² 2 ·d or greater or 100 g / m² 2 ·d or greater. The above moisture permeability is 50 g / m² 2 · If d is less than 1, biodegradation may not occur or may be excessively delayed even after disposal of the item.

[0040] Preferably, the moisture permeability of the resin cured product is 60 to 140 g / m² 2 ·d, 60 to 130 g / m² 2 ·d, 60 to 120 g / m 2·d, 60 to 110 g / m² 2 ·d, 70 to 140 g / m² 2 ·d, 70 to 130 g / m² 2 ·d, 70 to 120 g / m² 2 ·d, 70 to 110 g / m² 2 ·d, 80 to 140 g / m² 2 ·d, 80 to 130 g / m² 2 ·d, 80 to 120 g / m² 2 ·d, 80 to 110 g / m² 2 ·d, 90 to 140 g / m² 2 ·d, 90 to 130 g / m² 2 ·d, 90 to 120 g / m² 2 ·d, or 90 to 110 g / m 2 ·d may be, more preferably 70 to 120 g / m 2 ·d can be

[0041] As previously described, the polybutylene adipate terephthalate resin comprises repeating units derived from monomers of 1,4-butanediol, terephthalic acid, and adipic acid.

[0042] The above polybutylene adipate terephthalate resin may contain a repeating unit derived from terephthalic acid represented by the following chemical formula 1 (first repeating unit) and a repeating unit derived from adipic acid represented by the following chemical formula 2 (second repeating unit) in a molar ratio of 52:48 to 65:35, or 53:47 to 60:40, or 53:47 to 58:42, or 52:48 to 55:45, or 53:47 to 65:35.

[0043] [Chemical Formula 1]

[0044]

[0045] [Chemical Formula 2]

[0046]

[0047] In addition, the polybutylene adipate terephthalate resin may include a third repeating unit (butylene-terephthalate) derived from terephthalic acid and butanediol, and a fourth repeating unit (butylene-adipate) derived from adipic acid and butanediol, and such a structure may be represented by the following chemical formula 3.

[0048] [Chemical Formula 3]

[0049]

[0050] In the above chemical formula 3, m and n represent the molar ratio of each repeating unit, and m : n may be 52 : 48 ~ 65 : 35, or 53 : 47 ~ 60 : 40, or 53 : 47 ~ 58 : 42, or 52 : 48 ~ 55 : 45, or 53 : 47 ~ 65 : 35.

[0051] The polybutylene adipate terephthalate resin of the present invention satisfying the above-described composition can have biodegradability while also having enhanced moisture barrier properties, allowing for an appropriately controlled biodegradation rate. Accordingly, it is possible to provide a biodegradable resin for films or coatings that maintains excellent physical properties and functionality during use.

[0052] The above polybutylene adipate terephthalate resin may further include monomers derived from other types of dicarboxylic acid compounds in addition to terephthalic acid and adipic acid. The above dicarboxylic acid compounds may be aromatic dicarboxylic acid compounds having 8 to 14 carbon atoms, aliphatic dicarboxylic acid compounds, or a mixture of one or more of these. More specifically, they may be one or more selected from the group consisting of isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbendicarboxylic acid, or 2,5-thiophenedicarboxylic acid, malonic acid, succinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, pimelic acid, souveric acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, brasylic acid, tetradecanediic acid, fumaric acid, 2,2-dimethylglutaric acid, souveric acid, maleic acid, itaconic acid, and maleic acid, but are not limited thereto.

[0053] In addition, the polybutylene adipate terephthalate resin may have at least one of its two ends as a hydroxyl group (-OH) or a carboxyl group (-C(=O)OH), wherein the hydroxyl group or carboxyl group is C1-C 20 Structures substituted with alkyl groups, ester groups, urethane groups, silane groups, epoxy groups, acetyl groups, amide groups, acyl chloride groups, imide groups, etc. are also included in the scope of the present invention.

[0054] The above polybutylene adipate terephthalate resin may have a weight-average molecular weight of 70,000 g / mol or more or 80,000 g / mol or more, and 100,000 g / mol or less, 95,000 g / mol or less, 90,000 g / mol or less, or 85,000 g / mol or less. For example, it may be 70,000 to 100,000 g / mol, 70,000 to 90,000 g / mol, 70,000 to 85,000 g / mol, 80,000 to 100,000 g / mol, 80,000 to 90,000 g / mol, or 80,000 to 85,000 g / mol. Polybutylene adipate terephthalate resin satisfying the above weight-average molecular weight range can achieve physical properties as a film to be applied to mulching films, packaging films, or envelope films.

[0055] In this specification, the weight-average molecular weight of the resin can be measured by dissolving the subject to measurement in chloroform at a concentration of 1 mg / ml and then introducing the solution into a gel permeation chromatography instrument (Waters Alliance GPC System, Agilent PLgel 10 μm Guard (PL1110-1120)+PLgel Mixed-B (PL1110-6100)). At this time, polystyrene can be used as the standard polymer.

[0056] The above polybutylene adipate terephthalate resin may have a melting enthalpy (dsc) of 26 to 50 J / g, 26 to 48 J / g, 26 to 45 J / g, 26 to 43 J / g, 26 to 40 J / g, 26 to 37 J / g, 26 to 35 J / g, 26 to 33 J / g, 28 to 50 J / g, 28 to 48 J / g, 28 to 45 J / g, 28 to 43 J / g, 28 to 40 J / g, 28 to 37 J / g, 28 to 35 J / g, or 28 to 33 J / g.

[0057] The above polybutylene adipate terephthalate resin may have a crystallization temperature (Tc) of 50 to 115 ℃, 50 to 110 ℃, 50 to 100 ℃, 50 to 95 ℃, 50 to 90 ℃, 50 to 85 ℃, 50 to 80 ℃, 60 to 115 ℃, 60 to 110 ℃, 60 to 100 ℃, 60 to 95 ℃, 60 to 90 ℃, 60 to 85 ℃, 60 to 80 ℃, 70 to 115 ℃, 70 to 110 ℃, 70 to 100 ℃, 70 to 95 ℃, 70 to 90 ℃, 70 to 85 ℃, or 70 to 80 ℃.

[0058] The above polybutylene adipate terephthalate resin may have a glass transition temperature (Tg) of -28 to -10 ℃, -28 to -12 ℃, -28 to -14 ℃, -28 to -16 ℃, -28 to -18 ℃, -28 to -20 ℃, -27 to -12 ℃, -27 to -14 ℃, -27 to -16 ℃, -27 to -18 ℃, -27 to -20 ℃, -26 to -12 ℃, -26 to -14 ℃, -26 to -16 ℃, -26 to -18 ℃, or -26 to -20 ℃.

[0059] The above polybutylene adipate terephthalate resin may have a melting temperature (Tm) of 135 to 178 ℃, 135 to 175 ℃, 135 to 170 ℃, 135 to 165 ℃, 135 to 160 ℃, 135 to 155 ℃, 135 to 150 ℃, 137 to 178 ℃, 137 to 175 ℃, 137 to 170 ℃, 137 to 165 ℃, 137 to 160 ℃, 137 to 155 ℃, or 137 to 150 ℃.

[0060] In this specification, the melting enthalpy (dsc), crystallization temperature (Tc), glass transition temperature (Tg), and melting temperature (Tm) can be measured using differential scanning calorimetry. The resin composition can be measured by using a differential scanning calorimeter (DSC) to input a sample of 3 mg (with an error margin of 1 mg), heating it first to 200 ℃ at a heating rate of 10 ℃ / min under a nitrogen stream, cooling it to -60 ℃ at a heating rate of 10 ℃ / min, and then heating it secondarily to 180 ℃ at a heating rate of 10 ℃ / min.

[0061] In addition, the above-mentioned polybutylene adipate terephthalate resin has a melt index (MI) measured at 190°C with a 2.16 kg load according to ASTM D 1238. 2.16 ) may be about 25 g / 10min or more, about 30 g / 10min or more, about 35 g / 10min or more, or about 40 g / 10min or more, and about 100 g / 10min or less, about 90 g / 10min or less, about 80 g / 10min or less, about 70 g / 10min or less, or about 60 g / 10min or less, or about 50 g / 10min or less.

[0062] The polybutylene adipate terephthalate resin according to the present invention satisfying the above-mentioned thermal characteristics has a density of 150 g / m² 2 ·d or less, preferably 130 g / m² 2 ·d or less, more preferably 120 g / m² 2 It can have a controlled biodegradation rate by having a moisture permeability of d or less. Therefore, films made of the resin or articles coated with the resin can sufficiently maintain the physical properties originally required of these articles (e.g., mechanical properties such as tensile strength, tensile elongation, or tensile modulus) during use, and storage is easy.

[0063] When a film is manufactured using the above-mentioned polybutylene adipate terephthalate resin or a coating layer is formed on the surface of an article (substrate), uncoated portions (cracks) of a predetermined size may not occur in the film or coating layer. For example, when a film or coating layer with a thickness of approximately ~50 μm is formed using the above-mentioned polybutylene adipate terephthalate resin, cracks with a width of 0.5 μm or more may not occur. In particular, when the coated material is measured by energy dispersive spectroscopy (EDS), the coating layer may be formed continuously across the entire surface of the coated target.

[0064] Method for preparing a polybutylene adipate terephthalate resin composition

[0065] According to another embodiment of the present invention, the invention relates to a method for manufacturing a polybutylene adipate terephthalate resin that satisfies the moisture permeability of the above-mentioned range.

[0066] The above manufacturing method may include a first step of preparing a polybutylene adipate terephthalate prepolymer by polymerizing 1,4-butanediol, terephthalic acid, and adipic acid as monomers; and a second step of preparing a polybutylene adipate terephthalate resin by condensation polymerizing the prepolymer.

[0067] The first step above may first mix 1,4-butanediol, terephthalic acid, and adipic acid. The order of mixing is not particularly limited and may be administered sequentially in any order, and two or more components may be administered simultaneously.

[0068] In the first step above, terephthalic acid and adipic acid may be mixed such that the molar ratio is 52:48 to 65:35, or 53:47 to 60:40, or 53:47 to 58:42, or 52:48 to 55:45, or 53:47 to 65:35. If terephthalic acid is added in an amount of less than 52 mol% based on the combined total of 100 mol% of terephthalic acid and adipic acid, the moisture permeability of the resin increases, making it difficult to control the biodegradation rate. Additionally, some clumping may occur when coating with the resin, and appearance characteristics may deteriorate when manufactured into a film. If terephthalic acid is added in an amount exceeding 65 mol%, the biodegradation rate is too low, making it difficult to expect the originally intended biodegradable effect.

[0069] In the first step above, 1,4-butanediol may be added in an amount of 100 to 250 parts by weight per 100 parts by weight of adipic acid. The 1,4-butanediol not only contributes to molecular chain formation and esterification reactions, but may also serve as a medium and a dispersant.

[0070] In the first step above, a prepolymer can be prepared by polymerizing 1,4-butanediol, terephthalic acid, and adipic acid in the presence of a titanium (Ti)-based catalyst. The prepolymer refers to a polymer with a relatively low degree of polymerization obtained by stopping the polymerization reaction midway.

[0071] The above titanium (Ti)-based polymerization catalyst may be one or more selected from the group consisting of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium isobutoxide, and titanium citrate, but is not limited thereto.

[0072] In addition, the titanium (Ti)-based polymerization catalyst may be included in an amount of about 0.001 to about 10 parts by weight per 100 parts by weight of the adipic acid. Within this range, the esterification reaction of the monomer mixture can be appropriately mediated. If the amount of catalyst added is too small, the polymerization time may be prolonged, which may reduce productivity. If the amount of catalyst added is too large, the polymerization time may be shortened, but the possibility of discoloration of the final resin produced increases; therefore, the amount of heat stabilizer added must be increased in proportion to the amount of catalyst added, and the manufacturing cost increases.

[0073] A crosslinking agent (or branching agent) may be additionally added during the polymerization reaction of the first step above. When an esterification reaction is carried out by adding a crosslinking agent, an internally crosslinked prepolymer may be produced. Accordingly, the mechanical properties of the final polybutylene adipate terephthalate resin may be improved. The crosslinking agent is a low-molecular-weight compound containing three or more hydroxyl groups or three or more carboxyl groups within the molecule, and may use, for example, erythritol-based compounds, glycerol-based compounds, or citric acid, but is not limited thereto.

[0074] In the first step above, the polymerization reaction for the preparation of the prepolymer can be carried out at a temperature of 150 ℃ or higher, 170 ℃ or higher, 190 ℃ or higher, or 210 ℃ or higher, and 350 ℃ or lower, 320 ℃ or lower, or 290 ℃ or lower.

[0075] In the first step above, the polymerization reaction for the preparation of the prepolymer may be carried out for 10 minutes or more, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and, 240 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less, but is not limited thereto.

[0076] The polymerization reaction of the first step above can be carried out with stirring. At this time, the stirring speed is not particularly limited, but may be, for example, 10 to 100 rpm, 30 to 100 rpm, or 50 to 80 rpm.

[0077] In addition, the polymerization reaction in the first step above may be performed by adding nitrogen gas into the reactor. By performing the polymerization reaction under a nitrogen gas atmosphere, the generation of byproducts can be suppressed and the conversion rate of the monomer can be increased. The nitrogen gas may be supplied at a flow rate of 0.01 ml / min or more, 0.02 ml / min or more, 0.05 ml / min or more, 100 ml / min or less, 50 ml / min or less, or 10 ml / min or less, but is not limited thereto.

[0078] When a polybutylene adipate terephthalate prepolymer is prepared by the first step above, a second step of preparing a polybutylene adipate terephthalate resin by condensation polymerization of the prepolymer can be performed.

[0079] The above second step may include a step of pre-polycondensation of the prepolymer and a step of polycondensation.

[0080] The above pre-condensation reaction can be carried out in the presence of a titanium (Ti)-based polymerization catalyst. During the above pre-condensation reaction, polymer chains can be linked by the esterification reaction between the hydroxyl groups and carboxyl groups at the ends of the polybutylene adipate terephthalate prepolymer. Therefore, the titanium (Ti)-based polymerization catalyst used in the condensation polymerization reaction of the second step may be of the same or different type as that used in the first step.

[0081] In the second step above, a titanium (Ti)-based polymerization catalyst may be added in an amount of about 0.001 to about 0.5 parts by weight per 100 parts by weight of polybutylene adipate terephthalate prepolymer.

[0082] In addition, by adding a heat stabilizer during the pre-condensation reaction of the second step, discoloration of the finally produced polybutylene adipate terephthalate resin can be suppressed.

[0083] The above heat stabilizer may include one or more selected from the group consisting of phosphoric acid, phosphoric acid, trialkyl phosphate, and trialkyl phosphonoacetate, but is not limited thereto.

[0084] The above heat stabilizer may be added in an amount of about 0.001 to about 0.1 parts by weight per 100 parts by weight of the polybutylene adipate terephthalate prepolymer, but is not limited thereto.

[0085] During the pre-condensation reaction of the second step above, the temperature inside the reactor can first be raised to a temperature of 150 ℃ or higher, 170 ℃ or higher, 190 ℃ or higher, or 210 ℃ or higher, and 350 ℃ or lower, 320 ℃ or lower, or 290 ℃ or lower.

[0086] In addition, when the temperature of the reactor reaches the above temperature range, the pressure inside the reactor can be reduced until it reaches 10 to 100 mbar, 10 to 50 mbar, or 10 to 30 mbar. The reduction time may be performed for 10 minutes or more, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and, 240 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less, but is not limited thereto.

[0087] The above total condensation reaction may be carried out with stirring. At this time, the stirring speed is not specifically limited, but may be, for example, 10 to 100 rpm, 30 to 100 rpm, or 50 to 80 rpm.

[0088] After the above pre-condensation reaction, a condensation polymerization reaction may be performed. The above condensation polymerization reaction may be performed under conditions of 3 mbar or less, 2 mbar or less, 1.5 mbar or less, or 1.1 mbar or less, while maintaining the temperature inside the reactor at the temperature of the above pre-condensation reaction.

[0089] The above condensation polymerization reaction may be carried out with stirring. At this time, the stirring speed is not particularly limited, but may be, for example, 10 to 100 rpm, 30 to 100 rpm, or 50 to 80 rpm.

[0090] The above condensation polymerization may be performed until the torque of the stirrer reaches △10 to 30 Nm, △10 to 20 Nm, △15 to 30 Nm, or △15 to 20 Nm, but is not limited thereto.

[0091] In the present invention, by controlling the pressure conditions, stirring speed, and stirrer torque of the condensation polymerization reaction, the final molecular weight and melt index of the finally produced polybutylene adipate terephthalate resin can be controlled within a desired range.

[0092] film

[0093] According to another embodiment of the present invention, the invention relates to a biodegradable film comprising a polybutylene adipate terephthalate resin according to the present invention.

[0094] The biodegradable film of the present invention has low water vapor transmission and a controlled biodegradation rate. Accordingly, when the thickness of the film is 50 μm, the water vapor transmission measured under conditions of 38°C and 90% relative humidity is 150 g / m². 2 ·d or less, 140 g / m² 2 ·d or less, 130 g / m² 2 ·d or less, 120 g / m² 2 ·d or less, 110 g / m² 2 ·d or less, 105 g / m² 2 ·d or less or 100 g / m² 2 ·d or less, and 50 g / m² 2 ·d or greater, 60 g / m² 2 ·d or greater, 70 g / m² 2 ·d or greater, 80 g / m² 2 ·d or greater, 90 g / m² 2 ·d or greater or 100 g / m² 2 ·d may be greater than or equal to. Preferably, the moisture permeability of the film is 50 to 150 g / m² 2 ·d, 60 to 140 g / m² 2 ·d, 60 to 130 g / m² 2 ·d, 60 to 120 g / m 2 ·d, 60 to 110 g / m² 2 ·d, 70 to 140 g / m² 2 ·d, 70 to 130 g / m² 2 ·d, 70 to 120 g / m² 2 ·d, 70 to 110 g / m² 2 ·d, 80 to 140 g / m² 2 ·d, 80 to 130 g / m² 2 ·d, 80 to 120 g / m² 2 ·d, 80 to 110 g / m² 2 ·d, 90 to 140 g / m² 2·d, 90 to 130 g / m² 2 ·d, 90 to 120 g / m² 2 ·d, or 90 to 110 g / m 2 ·d may be, more preferably 70 to 120 g / m 2 ·d can be

[0095] The above film can be processed according to conventional and known processing methods used for film processing, and can be formed into a film through, for example, a casting process, an extrusion process, a bubble blowing process, a calendering process, or a sintering process.

[0096] The thickness of the above film is not specifically limited, but, for example, it may be 1 to 500 μm, specifically 10 to 200 μm, but is not limited thereto, and the thickness can be adjusted to a suitable thickness depending on the intended application.

[0097] The above film may be in the form of an agricultural mulching film, packaging material (e.g., food packaging material, bubble wrap, pharmaceutical packaging material, product protection packaging film, plastic container, etc.), shrink film, envelope material, or other film or sheet form that can be used as disposable tableware, straws, cups, disposable gloves, masks, etc., and may be in the form of a fiber that can be used as a fabric, knitted fabric, non-woven fabric, rope, etc.

[0098] The above-mentioned film has an appropriate biodegradation rate, so excellent physical properties and appearance characteristics can be maintained during the use or storage of the film, and it can be biodegraded after disposal.

[0099] The present invention will be explained in detail below through the following examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited by the following examples.

[0100] Examples

[0101] [Comparative Example 1] Preparation of Polybutylene Adipate Terephthalate (PBAT) Resin

[0102] 95.0 g of terephthalic acid and 90.5 g of adipic acid were prepared so that the molar ratio of terephthalic acid to adipic acid was 48:52. 182.5 g of 1,4-butanediol, the prepared 95.0 g of terephthalic acid, 90.5 g of adipic acid, and 0.053 g of titanium butoxide were added to a reactor. The reactor was heated to 230 ℃ under nitrogen purging, and the esterification reaction was performed while rotating a PT-paddle stirrer at 60 rpm to produce a prepolymer. The reaction was stopped after visually confirming that the effluent in the Dean Stark apparatus was more than 95% of the theoretical amount and that the reaction product had become transparent. Subsequently, 0.071 g of titanium butoxide and 0.054 g of triethylphosphonoacetate were added to the reactor. The reactor temperature was reset to 240 ℃, and a diaphragm pump was connected to carry out the pre-condensation reaction (PP) by gradually reducing the pressure from atmospheric pressure to 20 mbar over 45 minutes. After the reaction was completed, the diaphragm pump was replaced with an oil pump, and the condensation polymerization reaction (PC) was carried out at 240 ℃ and ≤ 1.1 mbar until the target torque (△20~30 Nm) was reached. However, the stirrer rpm was fixed at 60 rpm during both the pre-condensation reaction and the condensation polymerization reaction.

[0103] [Example 1] Preparation of Polybutylene Adipate Terephthalate (PBAT) Resin

[0104] 104.4 g of terephthalic acid and 81.4 g of adipic acid were prepared so that the molar ratio of terephthalic acid to adipic acid was 53:47. 181.7 g of 1,4-butanediol, the prepared 104.4 g of terephthalic acid, 81.4 g of adipic acid, and 0.053 g of titanium butoxide were added to a reactor. The reactor was heated to 230 ℃ under nitrogen purging, and the esterification reaction was performed while rotating a PT-paddle stirrer at 60 rpm to produce a prepolymer. The reaction was stopped after visually confirming that the effluent in the Dean Stark apparatus was more than 95% of the theoretical amount and that the reaction product had become transparent. Subsequently, 0.071 g of titanium butoxide and 0.054 g of triethylphosphonoacetate were added to the reactor. The reactor temperature was reset to 240 ℃, and a diaphragm pump was connected to carry out the prepolycondensation (PP) reaction by gradually reducing the pressure from atmospheric pressure to 20 mbar over 45 minutes. After the reaction was completed, the diaphragm pump was replaced with an oil pump, and the polycondensation (PC) reaction was carried out at 240 ℃ and ≤ 1.1 mbar until the target torque (△15~20 Nm) was reached. However, the stirrer rpm was fixed at 60 rpm during both the prepolycondensation and polycondensation reactions.

[0105] [Example 2] Preparation of Polybutylene Adipate Terephthalate (PBAT) Resin

[0106] 113.7 g of terephthalic acid and 72.4 g of adipic acid were prepared so that the molar ratio of terephthalic acid to adipic acid was 58:42. 180.8 g of 1,4-butanediol, the prepared 113.7 g of terephthalic acid, 72.4 g of adipic acid, and 0.053 g of titanium butoxide were added to a reactor. The reactor was heated to 230 ℃ under nitrogen purging, and the esterification reaction was performed while rotating a PT-paddle stirrer at 60 rpm to produce a prepolymer. The reaction was stopped after visually confirming that the effluent in the Dean Stark apparatus was more than 95% of the theoretical amount and that the reaction product had become transparent. Subsequently, 0.071 g of titanium butoxide and 0.054 g of triethylphosphonoacetate were added to the reactor. The reactor temperature was reset to 240 ℃, and a diaphragm pump was connected to carry out the pre-condensation reaction (PP) by gradually reducing the pressure from atmospheric pressure to 20 mbar over 45 minutes. After the reaction was completed, the diaphragm pump was replaced with an oil pump, and the condensation polymerization reaction (PC) was carried out at 240 ℃ and ≤ 1.1 mbar until the target torque (△15~20 Nm) was reached. However, the stirrer rpm was fixed at 60 rpm during both the pre-condensation reaction and the condensation polymerization reaction.

[0107] [Comparative Example 2] Preparation of Polybutylene Adipate Terephthalate (PBAT) Resin

[0108] 132.1 g of terephthalic acid and 54.7 g of adipic acid were prepared so that the molar ratio of terephthalic acid to adipic acid was 68:32. 179.1 g of 1,4-butanediol, the prepared 132.1 g of terephthalic acid, 54.7 g of adipic acid, and 0.053 g of titanium butoxide were added to a reactor. The reactor was heated to 230 ℃ under nitrogen purging, and the esterification reaction was performed while rotating a PT-paddle stirrer at 60 rpm to produce a prepolymer. The reaction was stopped after visually confirming that the effluent in the Dean Stark apparatus was more than 95% of the theoretical amount and that the reaction product had become transparent. Subsequently, 0.071 g of titanium butoxide and 0.054 g of triethylphosphonoacetate were added to the reactor. The reactor temperature was reset to 240 ℃, and a diaphragm pump was connected to carry out the pre-condensation reaction (PP) by gradually reducing the pressure from atmospheric pressure to 20 mbar over 45 minutes. After the reaction was completed, the diaphragm pump was replaced with an oil pump, and the condensation polymerization reaction (PC) was carried out at 240 ℃ and ≤ 1.1 mbar until the target torque (△15~20 Nm) was reached. However, the stirrer rpm was fixed at 60 rpm during both the pre-condensation reaction and the condensation polymerization reaction.

[0109] [Experimental Example 1] Evaluation of Weight-Average Molecular Weight and Thermal Properties

[0110] For the polybutylene adipate terephthalate (PBAT) resins prepared in Examples 1 and 2 and Comparative Examples 1 and 2 above, the weight-average molecular weight, glass transition temperature (Tg), melting temperature (Tm), crystallization temperature (Tc), melting enthalpy (dsc), and melt index (MI) were determined by the following method. 2.16 ) was measured.

[0111] 1) Weight-average molecular weight

[0112] After dissolving a polybutylene adipate terephthalate (PBAT) resin sample in chloroform at a concentration of 1 mg / ml, the weight-average molecular weight was measured under the following conditions using gel permeation chromatography (GPC: PL GPC220, Agilent Technologies).

[0113] - Evaluation temperature: 160 ℃

[0114] - Flow rate: 1 mL / min

[0115] - Sample: 50 µL supply at a concentration of 1 mg / 1 mL

[0116] - Calibration Curve: Polystyrene standard grades (9 types with molecular weights of 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000) used

[0117] 2) DSC (differential scanning calorimetry)

[0118] 3 mg (margin of error 1 mg) of polybutylene adipate terephthalate (PBAT) resin sample was introduced into a differential scanning calorimeter (DSC) and heated first to 180 °C at a heating rate of 10 °C / min under a nitrogen stream. Subsequently, it was cooled to -60 °C at a cooling rate of 10 °C / min and heated secondly to 200 °C at a heating rate of 10 °C / min. As thermal properties of the polybutylene adipate terephthalate (PBAT) resin, the glass transition temperature (Tg), melting temperature (Tm), melting enthalpy (△Hm) at the cold crystallization stage, and crystallization temperature (Tc) resulting from the first cooling were measured.

[0119] 3) Melt Index (MI) 2.16 )

[0120] For polybutylene adipate terephthalate (PBAT) resin samples, the melt index (MI) according to ASTM D1238 (condition E, 190°C, 2.16 kg load) 2.16 ) was measured.

[0121] Classification Molecular Weight (kDa) Tg (°C) Tm (°C) Tc (°C) Enthalpy of Melting (J / g) Melting Index (g / 10 min) Comparative Example 11 10-28.5 127.4 46.2 25.9 19 Example 18 2-25.8 139.5 71.1 29.5 49 Example 28 5-20.8 152.4 84.6 34.9 47 Comparative Example 274-10.9 174.6 118.3 48.3 53

[0122] [Experimental Example 2] Evaluation of Biodegradability Using Enzymes

[0123] Polybutylene adipate terephthalate (PBAT) resin samples prepared in Example 1 and Comparative Examples 1 and 2 were dissolved in chloroform and sprayed onto a plate. An enzyme cocktail solution containing cutinase and lipase capable of cleaving ester bonds was applied to the plate sprayed with resin. The reaction was carried out for 1 to 2 days at a mesophilic temperature (20 to 45 °C). Subsequently, the degree of biodegradability was evaluated by checking the extent of the clear zone expansion.

[0124] As shown in Figure 1, a clear zone was observed on the plate sprayed with the resin of Example 1 and Comparative Example 1, whereas no clear zone was observed on the plate sprayed with the resin of Comparative Example 2.

[0125] [Experimental Example 3] Evaluation of Water Vapor Permeability

[0126] In order to evaluate whether the biodegradation rate of the polybutylene adipate terephthalate (PBAT) resin prepared in the above examples could be controlled, the water vapor permeability of films prepared with the resins of Examples 1 and 2 and Comparative Example 1, which were confirmed to be biodegradable, was evaluated. Specifically, films with a thickness of approximately 50 μm were prepared using the resins prepared in Examples 1 and 2 and Comparative Example 1 under conditions of 150°C and a blown-up ratio of 1.8 using a Teach-Line-E20 BL200 mini blown film apparatus. Under conditions of a temperature of 38°C and a relative humidity of 90%, a certain amount of water was placed in a cup, the blown film was loaded onto it and capped, and the weight loss of water that evaporated over one day (24 hours) was measured using a measuring device (Labthink TSY-T3). From this, the water vapor transmission rate was calculated according to Equation 1 below, and the results are listed in Table 2 below.

[0127] [Equation 1]

[0128]

[0129] In Equation 1 above, the amount of water vapor passing through refers to the amount of water vapor (g) passing through the film-shaped resin, and the area of ​​the specimen is the area of ​​the film specimen (m² 2 It means ), and the time (day) is the time the experiment was performed, and the unit is day.

[0130] Water vapor permeability (g / m²) 2 ·d) 38 ℃, 90% RH Comparative Example 1168 Example 1102 Example 2100

[0131] As shown in Table 2 above, the moisture permeability, or water vapor permeability, of the films prepared from the resins of Examples 1 and 2 is approximately 110 g / m² 2 The level is less than or equal to ·d, and the moisture permeability of the film made from the resin of Comparative Example 1 is 168 g / m² 2 It could be seen that it was very high with ·d.

[0132] Through the above-described experiment, it was found that the polybutylene adipate terephthalate (PBAT) resin prepared according to the present invention has a controlled biodegradation rate, and that films or coating layers made of this resin suppress disintegration during use of the article, thereby maintaining excellent physical properties of the article, while possessing biodegradability after disposal.

[0133] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0134] The present invention is applicable to polybutylene adipate terephthalate (PBAT) resin and films containing the same.

Claims

As a polybutylene adipate terephthalate (PBAT) resin comprising repeating units derived from 1,1,4-butanediol, terephthalic acid, and adipic acid, The cured product of the above resin has a water vapor permeability of 50 to 150 g / m² measured under conditions of 38 ℃ and 90% relative humidity. 2 ·d, polybutylene adipate terephthalate resin.

2. In Paragraph 1, The cured product of the above resin has a water vapor permeability of 70 to 120 g / m² measured under conditions of 38 ℃ and 90% relative humidity. 2 ·d, polybutylene adipate terephthalate resin.

3. In Paragraph 1, Polybutylene adipate terephthalate resin having a weight-average molecular weight of 70,000 to 100,000 g / mol and a melting enthalpy of 26 to 50 J / g.

4. In Paragraph 1, The above polybutylene adipate terephthalate resin is a polybutylene adipate terephthalate resin having a crystallization temperature (Tc) of 50 to 115 ℃.

5. In Paragraph 1, The above polybutylene adipate terephthalate resin is a polybutylene adipate terephthalate resin having a glass transition temperature (Tg) of -28 to -10 ℃ and a melting temperature (Tm) of 135 to 170 ℃.

6. In Paragraph 1, Melt index (MI) of the above polybutylene adipate terephthalate resin measured at 190°C with a 2.16 kg load 2.16 Polybutylene adipate terephthalate resin having a content of 25 g / 10 min or more and 60 g / 10 min or less.

7. In Paragraph 1, The above polybutylene adipate terephthalate resin is a polybutylene adipate terephthalate resin containing repeating units derived from terephthalic acid and repeating units derived from adipic acid in a molar ratio of 52:48 to 65:

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8. A biodegradable film comprising a polybutylene adipate terephthalate resin according to any one of claims 1 to 7.

9. In Paragraph 8, The above film is a biodegradable film that is an agricultural mulching film, a packaging film, a shrink film, or a bag film.

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