Polybutylene adipate terephthalate resin composition and its manufacturing method

Abstract

The present invention relates to a polybutylene adipate terephthalate resin composition and a method for producing the same.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0010704 dated January 25, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a polybutylene adipate terephthalate resin composition and a method for producing the same. [Background technology]

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

[0004] Thermoplastic polymer resins, especially polyethylene films, have excellent mechanical properties and are harmless to the human body. However, they can be continuously deformed when heated. Therefore, they are widely used in hot seal bags for food packaging and agricultural mulching films. Due to their excellent functionality and low price, their consumption is increasing every year.

[0005] However, as interest in the national and social environment has grown in recent years, issues such as environmental problems like microplastics, human safety issues like endocrine disruptors, and the depletion of natural resources that are the raw materials for plastics have come to the fore.

[0006] In particular, it has become known that discarded plastics such as polyethylene film have recently flowed into the ocean, where they are broken down into extremely small microplastic particles by the ocean's currents and sunlight.

[0007] It is now known that countless billions, or even tens of billions, of these microplastics are floating in the ocean, where they enter the bodies of marine organisms, accumulate in ecosystems, and affect the entire food chain.

[0008] Therefore, research is needed into alternative materials to the thermoplastics that were previously used, and there is growing interest in materials such as polybutyleneadipate terephthalate (PBAT), a biodegradable polymer with flexible properties.

[0009] PBAT is mostly used in environmentally friendly consumer film applications where it can replace polyethylene or polyethylene terephthalate, etc., and appearance properties are particularly important. However, when the molecular weight of polybutylene adipate terephthalate is increased to improve mechanical properties, polymer gel is formed, which can hinder the appearance and reduce mechanical properties such as tensile strength and elongation. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a polybutylene adipate terephthalate resin composition that suppresses gel formation during the production process and has excellent mechanical properties and appearance properties.

[0011] The present specification also provides a method for producing a polybutylene adipate terephthalate resin composition. [Means for solving the problem]

[0012]

[0013] Provided herein is a polybutylene adipate terephthalate resin composition comprising a polybutylene adipate terephthalate resin, a chain extender, and a gel reducing agent.

[0014] The chain extenders and gel reducing agents may be present in dispersed form in the polybutylene adipate terephthalate resin.

[0015] According to an embodiment of the present invention, the chain extender may include a diisocyanate-based compound, for example, the chain extender may include one or more compounds selected from the group consisting of hexamethylene diisocyanate, methylene diphenyl diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

[0016] According to one embodiment of the invention, the chain extender is included in an amount of about 0.1 to about 10 parts by weight, or about 0.1 to about 5 parts by weight, most preferably about 0.2 to about 3 parts by weight, based on 100 parts by weight of the polybutylene adipate terephthalate.

[0017] According to one embodiment of the present invention, the gel reducing agent may include at least one selected from the group consisting of secondary alcohol compounds having 3 to 10 carbon atoms and tertiary alcohol compounds having 4 to 10 carbon atoms.

[0018] Specifically, the gel reducing agent may include one or more selected from the group consisting of 2,5-dimethyl-2,5-hexanediol, 2-phenyl-2-propanol, 2,3-hexanediol, 2,5-hexanediol, 2-methyl-1-phenyl-2-propanol, 2,4-pentanediol, isosorbide, cyclobutanediol, cyclopentanediol, and cyclohexanediol.

[0019] According to one embodiment of the invention, the gel reducing agent is included in an amount of 0.01 to 10 parts by weight, or about 0.01 to about 5 parts by weight, most preferably about 0.1 to about 1 part by weight, based on 100 parts by weight of the polybutylene adipate terephthalate.

[0020] According to one embodiment of the invention, the weight average molecular weight of the polybutylene adipate terephthalate resin may be about 50,000 to about 150,000, or about 100,000 to about 150,000, and most preferably about 130,000 to about 140,000.

[0021] According to one embodiment of the invention, the molecular weight distribution of the polybutylene adipate terephthalate resin may be about 3-5, or about 3-4.5, and most preferably about 3.5-4.

[0022] The present invention also provides a method for producing polybutylene adipate terephthalate, comprising: a polymerization step of producing a polymer by condensation polymerization of 1,4-butanediol, adipic acid, and terephthalic acid in the presence of a catalyst; a mixing step of adding a chain extender and a gel reducing agent to the polymer to produce a mixture; and a molding step of extruding the mixture.

[0023] In this case, the ratio of the molecular weight after extrusion to the molecular weight before extrusion is about 1 or more, or about 1 to about 2, most preferably about 1.3 to about 1.5, and the molecular weight can be increased by the extrusion process.

[0024] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention.

[0025] The singular expression includes the plural expression unless otherwise clearly indicated in the context.

[0026] As used herein, terms such as "comprises," "comprising," or "having" are intended to describe embodied features, numbers, steps, components, or combinations thereof, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations or additions thereof.

[0027] Additionally, in this specification, when a layer or element is referred to as being formed "on" another layer or element, this means that the layer or element is formed directly on the layer or element, or that other layers or elements can be additionally formed between layers, on the object, or on the substrate.

[0028] Although the present invention can be modified in various ways and has various forms, specific embodiments are illustrated and described in detail below. However, it should be understood that the present invention is not limited to the specific disclosed embodiments, and includes all modifications, equivalents, or alternatives falling within the spirit and technical scope of the present invention.

[0029] In this specification, the term polybutylene adipate terephthalate resin or polybutylene adipate terephthalate polymer is used to encompass not only polymer chains containing repeating units derived from butylene, adipate, and terephthalate, but also all forms in which a chain extender is incorporated into the middle of a polymer repeating unit through a chain extension reaction and is included in the polymer chain.

[0030] The present invention will be described in detail below.

[0031] As described above, in order to improve the mechanical properties of polybutylene adipate terephthalate, it is necessary to increase the molecular weight of polybutylene adipate terephthalate. However, when the molecular weight of polybutylene adipate terephthalate is increased, a polymer gel is formed, which may cause problems such as poor appearance and reduced mechanical properties such as tensile strength and elongation.

[0032] In most cases, polybutylene adipate terephthalate is produced through a polymerization process and an extrusion molding process for increasing the molecular weight of the polybutylene adipate terephthalate polymer produced in the polymerization process.

[0033] The polybutylene adipate terephthalate produced in the polymerization process does not have a very high molecular weight or high melt viscosity, making it easy to remove by-products such as gels.

[0034] However, the polybutylene adipate terephthalate polymer obtained after the extrusion molding process has a high molecular weight and its melt viscosity value is significantly increased, which causes a problem that by-products such as gel contained therein are difficult to remove.

[0035] As a result of continuing research to solve the above problems, the inventors of the present invention have discovered that a combination of specific compounds can suppress the formation of gel in polybutylene adipate terephthalate polymer, and have completed the present invention.

[0036] According to one aspect of the present invention, there is provided a polybutylene adipate terephthalate resin composition comprising a polybutylene adipate terephthalate resin, a chain extender, and a gel reducing agent.

[0037] The chain extenders and gel reducing agents may be present in dispersed form in the polybutylene adipate terephthalate resin.

[0038] In addition, in the polybutylene adipate terephthalate resin composition, the chain extender and the gel reducing agent may be present in the form of a reaction product formed by reacting with each other while being dispersed in the resin composition.

[0039] According to an embodiment of the present invention, the chain extender may include a diisocyanate-based compound, for example, the chain extender may include one or more compounds selected from the group consisting of hexamethylene diisocyanate, methylene diphenyl diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

[0040] According to one embodiment of the invention, the chain extender is included in an amount of about 0.1 to about 10 parts by weight, or about 0.1 to about 5 parts by weight, most preferably about 0.2 to about 3 parts by weight, based on 100 parts by weight of the polybutylene adipate terephthalate.

[0041] If the content of the chain extender is too low, the molecular weight of the polybutylene adipate terephthalate resin may not be sufficiently high. If the content of the chain extender is too high, the content of the polybutylene adipate terephthalate polymer gel, which is a reaction by-product, may be high.

[0042] Diisocyanate compounds are typical chain extenders used in polyester polymers such as the polybutylene adipate terephthalate of the present invention.

[0043] The isocyanate group contained in the diisocyanate compound can react with the hydroxyl group or carboxyl group at the polyester end to generate a urethane bond. Therefore, in the case of a diisocyanate compound containing two or more isocyanate groups in the molecule, the above-mentioned reactions proceed at both ends, linking the ends of the polyester polymer to extend the chain and increase the molecular weight of the polyester polymer.

[0044] When the urethane group generated in the intermediate process of the reaction reacts again with the isocyanate group of the chain extender, an alphanate-based compound is formed. Three or more polymer chains are linked to the nitrogen atom of this alphanate-based compound, which acts as a kind of crosslinking point, and a polymer gel is formed by such crosslinking.

[0045] In addition, when an isocyanate group reacts with moisture, a compound containing an amine group is generated, and when this compound reacts again with a chain extender, a urea bond can be generated. When such a urea group reacts again with a chain extender, a biuret compound is generated, which can also act as a crosslinking point to generate a polymer gel.

[0046] However, in the resin composition according to one embodiment of the present invention, the gel reducing agent is included, so that the formation of such gel during the chain extension of the polybutylene adipate terephthalate polymer can be prevented.

[0047] According to one embodiment of the present invention, the gel reducing agent may include at least one selected from the group consisting of secondary alcohol compounds having 3 to 10 carbon atoms and tertiary alcohol compounds having 4 to 10 carbon atoms.

[0048] Specifically, the gel reducing agent may include one or more selected from the group consisting of 2,5-dimethyl-2,5-hexanediol, 2-phenyl-2-propanol, 2,3-hexanediol, 2,5-hexanediol, 2-methyl-1-phenyl-2-propanol, 2,4-pentanediol, isosorbide, cyclobutanediol, cyclopentanediol, and cyclohexanediol.

[0049] The secondary alcohol compounds and tertiary alcohol compounds described above contain a hydroxy group in the molecule, and in terms of their molecular structure, have an appropriate degree of reactivity with the isocyanate group, and can effectively prevent the formation of the above-mentioned alphanate bond without inhibiting the chain extension reaction in which the chain of the polybutylene adipate terephthalate polymer is extended during the extrusion process.

[0050] According to one embodiment of the invention, the gel reducing agent is included in an amount of 0.01 to 10 parts by weight, or about 0.01 to about 5 parts by weight, most preferably about 0.1 to about 1 part by weight, based on 100 parts by weight of the polybutylene adipate terephthalate.

[0051]

[0052] If the content of the gel reducing agent is too high, the polymer chain extension reaction of polybutylene adipate terephthalate is inhibited, and the molecular weight of polybutylene adipate terephthalate is not increased sufficiently, and depolymerization of polybutylene adipate terephthalate occurs, and the physical properties of the resin composition are deteriorated. If the content of the gel reducing agent is too low, the gel reducing effect is not achieved.

[0053] According to one embodiment of the invention, the weight average molecular weight of the polybutylene adipate terephthalate resin may be about 50,000 to about 150,000, or about 100,000 to about 150,000, and most preferably about 130,000 to about 140,000.

[0054] Here, the weight average molecular weight is a value measured by GPC using polystyrene standards having molecular weights of 1,000, 10,000, 50,000, 70,000, 100,000, 120,000, 150,000, 170,000, and 200,000, respectively.

[0055] If the weight average molecular weight of the polybutylene adipate terephthalate resin is too low, the mechanical properties of the resin composition may be deteriorated. If the weight average molecular weight of the polybutylene adipate terephthalate resin is too high, the processability of the resin may be deteriorated.

[0056] According to one embodiment of the present invention, the molecular weight distribution of the polybutylene adipate terephthalate resin may be about 3-5, or about 3-4.5, and most preferably about 3.5-4.

[0057] If the molecular weight distribution value of the polybutylene adipate terephthalate resin is too low, there may be a problem of reduced processability, and if the molecular weight distribution value of the polybutylene adipate terephthalate resin is too high, there may be a problem of reduced mechanical properties of the resin composition.

[0058] The present specification also provides a method for producing polybutylene adipate terephthalate, comprising: a polymerization step of producing a polymer by condensation polymerization of 1,4-butanediol, adipic acid, and terephthalic acid in the presence of a catalyst; a mixing step of adding a chain extender and a gel reducing agent to the polymer to produce a mixture; and a molding step of extruding the mixture.

[0059] The catalyst is not particularly limited as long as it is widely used as a polyester polymerization catalyst in the technical field to which the present invention pertains.

[0060] Specifically, the catalyst may be at least one selected from the group consisting of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, and titanium isobutoxide.

[0061] For example, the catalyst may be titanium butoxide.

[0062] The catalyst can be used in an amount of about 0.001 parts by weight or more, about 0.005 parts by weight or more, or about 0.01 parts by weight or more, and about 10 parts by weight or less, about 5 parts by weight or less, or about 0.1 parts by weight or less, based on 100 parts by weight of adipic acid in the monomer mixture.

[0063] If the amount of catalyst added is too small, the polymerization time may be long and the productivity may be reduced. On the other hand, if the amount of catalyst added is too large, the polymerization time may be short, but the possibility of discoloration of the resulting polybutylene adipate terephthalate may increase, which may cause a problem that a separate additive such as a heat stabilizer must be added in proportion to the amount of catalyst added.

[0064] The 1,4-butanediol can be used in an amount of about 150 to about 250 parts by weight, or about 180 to about 220 parts by weight, based on 100 parts by weight of adipic acid in the monomer mixture.

[0065] This is the total amount of 1,4-butanediol required for polybutylene adipate terephthalate synthesis.

[0066] Polymerization process A prepolymer is a polymer with a relatively low degree of polymerization, in which the polymerization reaction is stopped midway in order to facilitate molding.

[0067] In one embodiment, the prepolymer corresponds to a polymer having a relatively low degree of polymerization produced by esterification of a monomer mixture including 1,4-butanediol, adipic acid, and terephthalic acid in the presence of the catalyst.

[0068] According to one embodiment of the present invention, initial polymer chains are formed around the surface of the catalyst, with the catalyst at the center.

[0069] Specifically, the monomer mixture may contain about 50 to about 150 parts by weight of the terephthalic acid based on 100 parts by weight of adipic acid in the monomer mixture.

[0070] Terephthalic acid may affect the crystallinity of the polymer due to its aromatic ring structure, but the polymer produced within the above range of content can have excellent mechanical properties and biodegradability.

[0071] For example, the monomer mixture may contain about 80 to about 120 parts by weight of the terephthalic acid based on 100 parts by weight of the adipic acid in the monomer mixture.

[0072] In addition, in the step of preparing the prepolymer, 0.1 to 1 part by weight of a crosslinking agent or branching agent can be added based on 100 parts by weight of adipic acid in the monomer mixture to carry out an esterification reaction.

[0073] When a crosslinking agent is added and an esterification reaction is carried out, an internally crosslinked prepolymer is produced, and the mechanical properties of the resin composition can be improved.

[0074] The crosslinking agent is a low molecular weight compound containing three or more hydroxy groups or three or more carboxy groups in the molecule, such as glycerol, pentaerythritol, citric acid, etc. For example, the crosslinking agent may be pentaerythritol.

[0075] The step of preparing the prepolymer is carried out at a temperature ranging from about 150 to about 350° C. for about 10 to about 120 minutes.

[0076] Within the above temperature and time ranges, the organic filler can be maintained uniformly dispersed and the prepolymer can be produced.

[0077] For example, the step of preparing the prepolymer is carried out at a temperature of about 150° C. or more, about 170° C. or more, about 190° C. or more, or about 210° C. or more, and about 350° C. or less, about 320° C. or less, about 290° C. or less, or about 250° C. or less, and for a time period of about 10 minutes or more, about 15 minutes or more, about 20 minutes or more, or about 25 minutes or more, and about 120 minutes or less, about 90 minutes or less, about 60 minutes or less, or about 40 minutes or less.

[0078] In the step of preparing the prepolymer, nitrogen gas may be injected. Specifically, when nitrogen gas is injected, water generated as a by-product can be quickly removed, thereby suppressing reverse reactions caused by water, improving the conversion rate of monomers, and increasing the molecular weight of polymer chains.

[0079] For example, nitrogen gas can be injected at about 0.001 ml / min or more, about 0.01 ml / min or more, about 0.02 ml / min or more, or about 0.05 ml / min or more, and about 100 ml / min or less, about 50 ml / min or less, about 10 ml / min or less, or about 5 ml / min or less.

[0080] During polymerization of the prepolymer, about 0.001 to about 10 parts by weight of a catalyst may be additionally added based on 100 parts by weight of adipic acid in the monomer mixture.

[0081] The catalyst initially added is likely to lose activity during the prepolymer production stage. For example, titanium, the central metal component of the catalyst, may react with water, a by-product of the esterification reaction, to form titanium oxide, and the functional groups present in the organic filler molecule may be substituted with the alkoxide sites of titanium alkoxide. Therefore, it is preferable to add additional catalyst immediately before the reaction.

[0082] For example, the additional catalyst may be used in an amount of about 0.001 parts by weight or more, about 0.005 parts by weight or more, or about 0.01 parts by weight or more and about 10 parts by weight or less, about 5 parts by weight or less, or about 0.1 parts by weight or less, based on 100 parts by weight of adipic acid in the monomer mixture.

[0083] After the catalyst is added, a heat stabilizer can be added, which can suppress discoloration of the final PBAT.

[0084] Specifically, about 0.001 to about 1 part by weight of a heat stabilizer can be added based on 100 parts by weight of adipic acid in the monomer mixture.

[0085] During polymerization of the prepolymer, the method may include a step of increasing the temperature of a reactor containing the prepolymer until the temperature reaches a range of about 150 to about 350° C.; after the increase in temperature, reducing the pressure of the reactor until the pressure reaches about 0.1 to about 0.00001 atm; and after the reduction in pressure, maintaining the pressure and temperature and terminating the reaction after about 2 to about 8 hours.

[0086] For example, the temperature of the reactor containing the prepolymer can be increased until it reaches a temperature range of about 150°C or more, about 170°C or more, about 190°C or more, or about 210°C or more, and about 350°C or less, about 320°C or less, about 290°C or less, or about 250°C or less.

[0087] One to ten minutes after reaching the above temperature range, the pressure in the reactor can be reduced to a pressure range of about 0.00001 atm or more, about 0.00005 atm or more, about 0.0001 atm or more, or about 0.0002 atm or more, and about 0.1 atm or less, about 0.05 atm or less, about 0.03 atm or less, or about 0.01 atm or less.

[0088] After the reduction in pressure, the pressure and temperature are maintained to carry out the reaction, and the reaction can be terminated after about 2 hours or more, about 2.2 hours or more, about 2.4 hours or more, or about 3 hours or more and about 8 hours or less, about 7.5 hours or less, about 7 hours or less, or about 6 hours after the start of the reaction.

[0089] A chain extender and a gel reducing agent are then added to the polymer obtained in this manner to produce a mixture.

[0090] When preparing the mixture, the obtained polymer may be pulverized and then mixed with a chain extender and a gel reducing agent, etc. The mixing method may be a general method used for producing a blending resin in the technical field to which the present invention belongs, and in particular, a general method used for feeding a polymer obtained by polymerization into an extruder may be used.

[0091] The mixture is then extruded.

[0092] The extruder used here may have different configurations depending on the conditions, and generally, a twin screw extruder is preferred since it is advantageous for mixing and molding.

[0093] If the amount of resin composition fed to the extruder is too large or the molecular weight of the resin is too high, the extrusion pressure increases and overload occurs, which not only affects the physical properties of the extruded resin molded product but also causes mechanical problems. Therefore, it is preferable to keep the extrusion pressure as low as possible, taking into account the discharge rate and residence time.

[0094] The diameter and size of the extruder can be determined based on extrusion conditions such as the discharge rate, but the ratio of the screw length to the outer diameter (L / D) is preferably about 40 or more, or about 40 to about 60, and most preferably about 40 to about 50.

[0095] The extrusion temperature may be about 160° C. to about 250° C., preferably about 180° C. to about 220° C. If the extrusion temperature is too high, the molecular weight may decrease due to thermal decomposition of the polymer, whereas if the extrusion temperature is too low, the melting efficiency of the polymer may decrease.

[0096] In this case, the ratio of the molecular weight after extrusion to the molecular weight before extrusion is about 1 or more, or about 1 to about 2, most preferably about 1.3 to about 1.5, and the molecular weight can be increased by the extrusion process. Effect of the Invention

[0097] The polybutylene adipate terephthalate resin composition according to one embodiment of the present invention suppresses gel formation during the manufacturing process and has excellent mechanical properties and appearance properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0098] The functions and effects of the present invention will be described in more detail below through specific examples of the present invention, however, these examples are presented as examples of the present invention and do not define the scope of the invention.

[0099] <Production Example> A polymerization reactor was charged with 1,220 g of 1,4-butanediol, 606 g of adipic acid, 634 g of terephthalic acid, 0.77 g of pentaerythritol, and 1.0 mmol of titanium butoxide, and the temperature was maintained at about 230° C., and the reaction was allowed to proceed for about 4 hours under a nitrogen atmosphere to produce a prepolymer.

[0100] After the prepolymer was produced, triethylphosphonoacetate, a thermal stabilizer, was added so that the phosphorus (P) atom content in the resulting polymer was about 60 ppm, and the mixture was stirred for about 5 minutes to uniformly disperse the thermal stabilizer in the polymer.

[0101] Then, about 0.5 mmol of titanium butoxide was added to the reactor, and the temperature was increased to about 245° C. When the temperature of the reactor reached about 245° C., the pressure was reduced to allow polycondensation to proceed.

[0102] When the torque value of the reactor reached about 100 Ncm, the reaction was stopped and polybutylene adipate terephthalate polymer was obtained. (Mw: 93,600)

[0103] Example 1 The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.75 parts by weight of a chain extender hexamethylene diisocyanate and about 0.5 equivalents of a gel reducing agent 2-phenyl-2-propanol were added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0104] Example 2 The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.75 parts by weight of a chain extender hexamethylene diisocyanate and about 0.2 equivalents of a gel reducing agent 2,5-dimethyl-2,5-hexanediol were added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0105] Example 3 The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.75 parts by weight of a chain extender hexamethylene diisocyanate and about 0.2 equivalents of a gel reducing agent 2,3-hexanediol were added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0106] Reference example The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.75 parts by weight of a chain extender hexamethylene diisocyanate and about 1.0 equivalent of a gel reducing agent 2,5-dimethyl-2,5-hexanediol were added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0107] Comparative Example 1 The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.75 parts by weight of a chain extender, hexamethylene diisocyanate, was added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0108] Comparative Example 2 The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.5 parts by weight of a chain extender, hexamethylene diisocyanate, was added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0109] Comparative Example 3 The polybutylene adipate terephthalate polymer obtained in the above-mentioned manufacturing example was freeze-dried and pulverized, and then about 0.75 parts by weight of a chain extender hexamethylene diisocyanate and about 0.2 equivalents of glycerol were added to a small twin-screw extruder relative to 100 parts by weight of polybutylene adipate terephthalate, and extrusion was carried out to obtain a pellet-shaped resin composition.

[0110] Molecular weight and molecular weight distribution determination The molecular weight and molecular weight distribution were measured using gel permeation chromatography (GPC, Waters PL-GPC220) under the following conditions, and the measured values ​​are summarized in the table below. Column used: Polymer Laboratories PLgel MIX-B 300mm Evaluation temperature: 160℃ Solvent: 1,2,4-trichlorobenzene Flow rate: 1mL / min Sample: 200μl supplied at a concentration of 10mg / 10mL Calibration curve: Uses polystyrene standards (molecular weight: 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000, 9 types)

[0111] Gel content determination The pellet-shaped resin compositions produced in the above Examples, Reference Examples, and Comparative Examples were charged into a blow extruder, and blow molding was carried out under conditions of a temperature of 160° C. and a BUR of 1.7.

[0112] A film of about 50 μm in thickness was made, and cut into a size of about 5 cm in length and width to prepare a measurement sample. The number of gels present in the film was then measured using a CCD camera. The gels were round in shape, and the size was distributed between about 20 and 500 μm. The measured number of gels was calculated as a ratio to Comparative Example 1, and is summarized in the table below. [Table 1]

[0113] Referring to the table, it can be clearly seen that the resin composition according to the embodiment of the present invention has no significant change in molecular weight compared to the comparative example, and at the same time, the generation of gel during extrusion molding is significantly reduced.

[0114] Therefore, it is believed that the polybutylene adipate terephthalate resin composition according to one embodiment of the present invention has excellent mechanical properties and appearance properties when applied to applications such as environmentally friendly consumer product films.

Claims

1. Polybutylene adipate terephthalate resin, A chain extender, and including a gel reducing agent, Polybutylene adipate terephthalate resin composition.

2. The polybutylene adipate terephthalate resin composition of claim 1 , wherein the chain extender comprises a diisocyanate compound.

3. The polybutylene adipate terephthalate resin composition according to claim 1, wherein the chain extender is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polybutylene adipate terephthalate.

4. The polybutylene adipate terephthalate resin composition according to claim 1, wherein the gel reducing agent comprises at least one selected from the group consisting of secondary alcohol compounds having 3 to 10 carbon atoms and tertiary alcohol compounds having 4 to 10 carbon atoms.

5. The polybutylene adipate terephthalate resin composition of claim 1, wherein the gel reducing agent comprises one or more selected from the group consisting of 2,5-dimethyl-2,5-hexanediol, 2-phenyl-2-propanol, 2,3-hexanediol, 2,5-hexanediol, 2-methyl-1-phenyl-2-propanol, 2,4-pentanediol, isosorbide, cyclobutanediol, cyclopentanediol, and cyclohexanediol.

6. The polybutylene adipate terephthalate resin composition according to claim 1, wherein the gel reducing agent is contained in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the polybutylene adipate terephthalate.

7. The polybutylene adipate terephthalate resin composition according to claim 1, wherein the weight average molecular weight of the polybutylene adipate terephthalate resin is 50,000 to 150,000.

8. The polybutylene adipate terephthalate resin composition according to claim 1, wherein the molecular weight distribution of the polybutylene adipate terephthalate resin is 3 to 5.

9. In a method for producing polybutylene adipate terephthalate, a polymerization step of condensation polymerizing 1,4-butanediol, adipic acid, and terephthalic acid in the presence of a catalyst to produce a polymer; mixing the polymer with a chain extender and a gel reducing agent to produce a mixture; and The mixture is extruded. Method for producing polybutylene adipate terephthalate.

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