KR20100036872A - Biodegradable resin composition, method for production thereof and biodegradable film therefrom - Google Patents

Abstract

PURPOSE: A biodegradable film is provided to ensure excellent mechanical property using a peroxide-based high temperature initiator and to improve biodegradability and heat adhesive strength of a film using plasticized starch. CONSTITUTION: A biodegradable resin composition comprises 10-40 parts by weight of aliphatic/aromatic copolyester resin and 10-50 parts by weight of polylactic acid based on 100.0 parts by weight of the biodegradable resin composition; 0.01-2.0 parts by weight of peroxide-based high temperature initiator based on 100.0 parts by weight of a mixture of the aliphatic/aromatic copolyester resin and polylactic acid; 10-50 parts by weight of starch based on 100.0 parts by weight of the biodegradable resin composition; and 1-10 parts by weight of starch plasticizer, 0.1-5 parts by weight of starch destructive agent, and 0.1-3.0 parts by weight of compatibilizer based on 100.0 parts by weight of starch.

Description

Biodegradable resin composition, preparation method thereof and biodegradable film produced therefrom {BIODEGRADABLE RESIN COMPOSITION, METHOD FOR PRODUCTION THEREOF AND BIODEGRADABLE FILM THEREFROM}

The present invention relates to a biodegradable resin composition having excellent mechanical properties and processability, and a method for preparing the same. More specifically, the present invention relates to a biodegradable aliphatic / aromatic copolyester resin and a high temperature initiator of polylactic acid (PLA) and a peroxide system as main components. A biodegradable resin composition prepared by compounding the mixture comprising a starch, a starch plasticizer, a starch structure breaker, a compatibilizer through a side hopper and compounded in a twin screw extruder, a method for producing the same It relates to a biodegradable film produced therefrom.

Such a biodegradable film of the present invention exhibits excellent mechanical properties compared to a control without a high temperature initiator of a peroxide system, and at the same time, plasticized starch is added to improve biodegradability and improve thermal adhesive strength of the film. It induces a radical reaction of polylactic acid through the use of a high temperature initiator of peroxide-based compounding in the compounding process of mixing the composition to increase the side chain length to increase the molecular weight and increase the viscosity of the resin and the base resin of the final composition It is proved that the mechanical properties and formability of the film, such as tensile and tear strength, are improved during film production.

Plastic has been used as an important material that is indispensable in real life because it is light, easy to process and mass-produced, and has excellent durability, chemical resistance and mechanical properties. However, due to the increasing severity of environmental pollution around the world, and plastic wastes, especially disposable wastes, as the main cause of environmental pollution, the application and development of biodegradable resins in disposables is being actively carried out, especially those manufactured using petroleum. Compared to plastics, polylactic acid has been spotlighted as an environmentally friendly resin due to its relatively low carbon dioxide emissions.

Moreover, there is no concern about depletion of resources as compared to petroleum resin as the infinite resource that can be continuously produced, and the use of products using this is being expanded every year. The biodegradable resins developed so far are polycaprolactone and diol-dieside series chemically synthesized starting from polylactide, epsilon caprolactone monomer synthesized by ring-opening reaction of lactic acid or lactide in the presence of a chemical catalyst or enzyme. Aliphatic polyesters, and polyhydroxybutylate (PHB) produced by in vivo synthesis of other microorganisms.

On the other hand, biodegradable resins are not only expensive, but are also limited in use due to their weak physical properties compared to conventional plastic products. Polylactic acid is relatively inexpensive compared to other biodegradable resins, and its consumption is increasing, but heat resistance is low, it is weak to impact, and polycaprolactone has a disadvantage of low workability due to its low melting point. When the aliphatic polyester is applied to the film, there is a disadvantage in that storage stability and heat sealability are weak and thus the practical use is delayed. The aliphatic / aromatic copolyester prepared by adding the aromatic monomer to compensate for the weakness of the physical properties, but there is a disadvantage that the decomposition rate is lowered. Accordingly, there have been attempts to reduce costs and improve biodegradability by mixing starch, which is a natural substance, in a biodegradable resin. However, in general, in applying starch to biodegradable resins, there is a problem in that the amount of starch is restricted and the quality of the product is deteriorated due to the decrease in physical properties due to the hydrophilicity and processability of the starch.

In order to improve the above problems and impart thermoplasticity to starch, glycerin, sorbitol, glucose with water as a plasticizer of starch (USP 3,949,145, EP 32802A1); And a method of plasticizing starch using derivatives or other plasticizers (eg, butanediol, propanediol, etc.) in addition to the above known plasticizers (Korean Patent Publication No. 93-701529) has been proposed. In addition, starch is prepared by compounding with biodegradable resin after preparation of thermoplastic starch by separate device and process (Korea Patent Registration No. 10-0339789) or starch based on biodegradable aliphatic polyester resin and starch as main components Method for preparing by adding plasticizer, starch structure breaker, etc. (Korea Patent Registration No. 10-0465980), Method for preparing biodegradable aliphatic polyester resin and polylactic acid by adding chain extender in twin screw extruder (Korea Patent Registration No. 10-0642289), and a method of using acrylic acid or methacrylic acid as a commercial catalyst between thermoplastic starch and biodegradable resin (Korean Patent Publication No. 97-42813) is also known.

However, the biodegradable resin compositions prepared by these conventional methods have problems such as high production cost, starch carbonization, and lack of physical properties due to deterioration in processability during product manufacturing. Particularly, when the plasticizer treatment step for imparting thermoplasticity to starch and the chemical modification step for improving physical properties are carried out in two steps, the burden of manufacturing cost and the complexity of the process cannot be ignored.

Alternatively, attempts have been made to blend 7 to 60 parts by weight of polybutylene succinate (including polybutylene succinate-co-butylene adipate) based aliphatic polyester to polylactic acid (or a copolymer thereof) (Japan Korean Patent Laid-Open Publication No. 1997-111107), and a product molded using the resin thus obtained shows a disadvantage that the physical properties of the product significantly decrease over time. As a conventional technique for improving the disadvantages of such biodegradable resins, Korean Patent Laid-Open Publication No. 2001-0032052 discloses polylactic acid (or a copolymer thereof), adipic acid as dicarboxylic acid and succinic acid and aliphatic diol. Add 30-70% of the brand name Bionolle 3001, a polybutylene succinate-based copolymer polycondensation-polymerized using 4-butanediol, to 100 parts by weight of polylactic acid, and compound the two components using an extruder. In Korea Patent Registration No. 10-428687 No. 10-428687 biodegradation to prepare a composition of 3 to 65 parts by weight of polylactic acid with compounding using a twin screw extruder based on 100 parts by weight of aliphatic polyester and aliphatic / aromatic copolyester The manufacturing method of the resin composition is shown. In this case, due to the high melting point of polylactic acid in the compounding process of polylactic acid (or its copolymer) and polybutylene succinate (or its copolymer), the thermal stability of the resin produced during extrusion at high temperatures is significantly reduced. The mechanical properties of the resin thus produced are also reduced.

The present inventors conducted extensive research to provide a method of simultaneously improving the physical properties and the process of imparting thermoplasticity to starch and a chemical reforming process to improve the physical properties through reaction extrusion process. The present invention has been completed.

That is, the present invention improves the physical properties of polylactic acid and aliphatic / aromatic copolyester through the reaction extrusion process, and simultaneously performs the thermoplasticization process of starch on the improved resin and the chemical reforming process for improving the physical properties in an extruder. It is an object of the present invention to provide a method for producing a biodegradable resin composition containing plasticized starch, which has excellent physical properties, dispersibility and degradability in a simpler and cheaper process.

SUMMARY OF THE INVENTION An object of the present invention is achieved by a method of reacting and extruding polylactic acid and aliphatic / aromatic copolyester using a high temperature initiator of a peroxide system as a modifier of polylactic acid in a method for compounding a biaxial extruder. do. The present invention also provides a manufacturing method comprising starch, a plasticizer, a starch structure breaker, and a compatibilizer through plasticization of starch at the same time through a side feeder to thereby plasticize the final biodegradable resin composition.

Biodegradable film made of a biodegradable resin composition according to the present invention is superior in tensile strength, tear strength, thermal bonding strength, compared to the resin film made of a conventional biodegradable resin, overcome the problems of use due to low physical properties It can be contributed greatly to the improvement of environment by being fully biodegradable in nature.

According to the method of the present invention, by adding a high temperature initiator of the peroxide-based as a modifier to induce the radical reaction of polylactic acid to improve the viscoelasticity (melt elasticity) to improve the impact strength of the blend of polylactic acid and aliphatic / aromatic copolyester The plasticized starch added at the same time can be used to obtain a film having excellent thermal adhesive strength and biodegradability.

The present invention is a biodegradable resin composition, 10 to 40 parts by weight of aliphatic / aromatic copolyester resin and 10 to 50 parts by weight of polylactic acid, aliphatic / aromatic copolyester resin and polylactic acid based on 100 parts by weight of the biodegradable resin composition. 0.01 to 2.0 parts by weight of a peroxide-based high temperature initiator, based on 100 parts by weight of a mixture of 10 to 50 parts by weight of starch, and 1 to 10 parts by weight of starch, based on 100 parts by weight of starch. It provides a biodegradable resin composition comprising a plasticizer, 0.1 to 5 parts by weight of starch structure breaker and 0.1 to 3.0 parts by weight of compatibilizer.

The biodegradable resin composition of the present invention is a resin composition obtained by mixing 10 to 40 parts by weight of aliphatic / aromatic copolyester and polylactic acid (PLA) in a range of 10 to 50 parts by weight based on 100 parts by weight of the final biodegradable resin composition. To the main hopper of the twin-screw extruder, and the high-temperature initiator of the peroxide system is added in the range of about 0.01 to 2.0 parts by weight based on 100 parts by weight of the mixed resin composition, and the starch is passed through the side hopper to the final biodegradable resin composition. 10 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight, based on 100 parts by weight of starch, further 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, 0.1 to 6 parts by weight of starch structure breaker, preferably 0.1 to 5 parts by weight, and 0.1 to 3.0 parts by weight of compatibilizer are added to the twin screw extruder. It is made through compounding. The above-mentioned resin mixture is introduced into the main hopper of the twin screw extruder to carry out the first reaction extrusion at a temperature range of about 180 to about 220 ° C., and to prepare a plasticized and mixed blend of starch introduced through the side hopper. To prepare a biodegradable resin composition prepared through secondary compounding under a vacuum degree of less than 10torr in the temperature range.

In such a resin composition, when the aliphatic / aromatic copolyester is less than 10 parts by weight, the tear strength of the film may be remarkably lowered. When the aliphatic / aromatic copolyester is more than 40 parts by weight, the productivity is lowered due to the decrease in the cooling property of the film and the increase in the product price. Can cause.

Another component, polylactic acid, is less than 10 parts by weight, it is difficult to expect the effect of improving the tensile strength, cooling, transparency of the advantages of polylactic acid, and when it exceeds 50 parts by weight tear strength and ductility of the disadvantages of polylactic acid The degradation can lower the quality of the film.

The weight composition ratio of the raw material composition is preferably 10 to 40 parts by weight of aliphatic / aromatic copolyester and 10 to 50 parts by weight of polylactic acid based on 100 parts by weight of the final biodegradable resin composition. In addition, in the case of starch, which is another component of the final biodegradable resin composition, when it exceeds 50 parts by weight, the processability and tensile strength of the film may be reduced and productivity may be reduced. Strength and biodegradability may be reduced. More preferably, the content of starch of the final product is 10 to 30 parts by weight. Biodegradable aliphatic / aromatic copolyester resins use an aromatic dicarboxylic acid component having a benzene ring such as dimethyl terephthalate and terephthalic acid as the dicarboxylic acid component of the resin together with aliphatic dicarboxylic acids such as succinic acid and adipic acid. A resin produced by condensation polymerization with an aliphatic (including cyclic aliphatic) glycol containing any one or more selected from 1,4-butanediol and ethylene glycol. At this time, the composition ratio of aliphatic dicarboxylic acid and aromatic dicarboxylic acid is composed of a molar ratio of 60:40 to 50:50. Polylactic acid has isomers and is a polymer based on lactic acid units in L-, D- or DL- form and the polylactic acid used in the present invention is a homopolymer of D-lactic acid or a copolymer of L- and D-lactic acid. It may be.

One of the greatest features of the present invention is the use of a high temperature initiator of the peroxide system in order to take advantage of polylactic acid, such as tensile strength and cooling, and to improve compatibility and viscoelasticity with other disadvantages. The high temperature initiator rapidly forms radicals at a high temperature of 200 ° C. or higher to induce radical reactions of polylactic acid, thereby extending chains, thereby improving melt elasticity of the resin, and thus, tearing steel, which is a disadvantage of physical properties of the film, in particular polylactic acid. There is an effect that the degree is improved. Types of high-temperature initiators include di-tert-butylperoxyhexahydroterephthalate, di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butylperbenzoate, di-tert Butyl peroxide, etc., and the amount thereof is suitably in the range of 0.01 to 2.0 parts by weight based on 100 parts by weight of the aliphatic polyester mixture. In addition, the starch used to improve the thermal adhesive strength and biodegradability of the film, which is one of the characteristics of the present invention, corn starch, potato starch, tapioca starch, wheat starch, rice starch and the modified starch alone or Mixtures of two or more may be used. Modified starches that can be used in the present invention include alpha starch, acid treated starch, acetyladipic acid starch, oxide starch, octenylsuccinate starch and the like.

Glycerin, diglycerin, ethylene glycol, propylene glycol, 1,4-butanediol, sorbitol, sorbitol acetate, amino sorbitol, sorbitol diacetate may be used as the starch plasticizer, and the content of the plasticizer is 1 to 10 based on 100 parts by weight of starch. When used in parts by weight and less than 1 part by weight may be insufficient plasticization of starch and when added more than 10 parts by weight may increase the adhesion of the film may be difficult to process.

As the starch structure breaker, urea, sodium potassium, calcium hydroxide, alum compound can be used. Starch structure breaker content is used in the range of 0.1 to 5 parts by weight based on 100 parts by weight of starch, if less than 0.1 parts by weight of starch structure is insufficient to deteriorate film properties, if more than 5 parts by weight of aliphatic poly Deterioration of the physical properties of the ester resin may cause the strength of the film to be lowered.

Starch is a hydrophilic substance and is compatible with hydrophobic aliphatic / aromatic copolyesters. Compatibilizers can be used to compensate for this. As compatibilizers, glycidyl methacrylate, ethylene vinyl alcohol, and polyvinyl having both hydrophilic and hydrophobic groups are used. Alcohol, ethylene vinyl acetate can be used, the content is used in the range of 0.1 to 3.0 parts by weight, if less than 0.1 parts by weight lacks the role as a compatibilizer, and when more than 3.0 parts by weight can lead to degradation of biodegradability.

In addition, in the present invention, additives commonly used in the art may be mixed as necessary to prevent deterioration of physical properties. Such additives include heat stabilizers, antioxidants, ultraviolet stabilizers, lubricants, slip agents, hydrolysis inhibitors, inorganic fillers, and the like.

As the thermal stabilizer, triphenyl phosphate, trimethyl phosphate, and the like may be used, and may be used in the range of 0.1 to 1.0 parts by weight based on 100 parts by weight of the total resin composition.

The antioxidant is a phenol-based antioxidant, Adekastab AO series, Irgafos series may be used in the range of 0.1 to 1.0 parts by weight based on 100 parts by weight of the total resin composition.

The UV stabilizer includes a HALS compound having an amine group and may be used in the range of 0.1 to 0.8 parts by weight based on 100 parts by weight of the total resin composition.

Lubricants include amide-based PE wax and may be used in the range of 0.1 to 1.0 parts by weight based on 100 parts by weight of the total resin composition.

As the slip agent, amide based erocaramide, oleamide and the like may be used in the range of 0.01 to 1.0 parts by weight based on 100 parts by weight of the total resin composition.

As the hydrolysis inhibitor, the polycarbodiimide series may be used in the range of 0.1 to 1.0 parts by weight based on 100 parts by weight of the total resin composition.

As the inorganic filler, talc, calcium carbonate, clay, barium sulfate, titanium dioxide, carbon black, mica and the like can be used, and the average particle diameter is in the range of 0.1 to 30 parts by weight based on 100 parts by weight of the total resin composition. Can be used as

In addition, the present invention is a method for producing a biodegradable resin composition, based on 100 parts by weight of the biodegradable resin composition 10 to 40 parts by weight of aliphatic / aromatic copolyester resin and 10 to 50 parts by weight of polylactic acid, and aliphatic / aromatic nose Mixing 0.01 to 2.0 parts by weight of the peroxide-based high temperature initiator in a mixer to produce a first mixture based on 100 parts by weight of the mixture of polyester resin and polylactic acid, first extruding the resulting first mixture, and producing 10 to 50 parts by weight of starch and 0.1 to 3.0 parts by weight of compatibilizer, and 1 to 10 parts by weight of starch plasticizer and 0.1 to 5 parts by weight, based on 100 parts by weight of starch, based on 100 parts by weight of the biodegradable resin composition Adding and mixing the starch structure breaker to prepare a second mixture, and 10 second to Including the step of extruding the second under vacuum, there is provided a method for producing a biodegradable resin composition of claim 1.

Preferably, the present invention peroxide to a resin composition in which 10 to 40 parts by weight of aliphatic / aromatic copolyester and polylactic acid (PLA) are mixed in a range of 10 to 50 parts by weight based on 100 parts by weight of the final biodegradable resin composition. The high temperature initiator of the system was added in the range of about 0.01 to 2.0 parts by weight based on 100 parts by weight of the mixed resin composition, and then introduced into the biaxial extruder main hopper, and after the first reaction extrusion process at a temperature in the range of about 180 to 220 ° C. 2 Starch, starch plasticizer, starch structure breaker, compatibilizer, introduced through the side hopper during the second extrusion process, and the secondary comb for about 1 to 3 minutes under vacuum of less than 10 torr at temperatures ranging from about 150 to 200 ° C. It provides a method for producing a biodegradable resin composition comprising the step of compounding (compounding).

In the above composition, the raw material component is introduced into a twin screw extruder, and when the first reaction extrusion is performed, the extrusion temperature is performed in the range of about 180 ° C to 220 ° C. More preferably, it is 200-220 degreeC. When the extrusion temperature is lower than 180 ℃, the decomposition rate of the high temperature initiator is slowed down and the reaction activity is reduced, the physical properties of the aliphatic / aromatic copolyester and polylactic acid may not be improved properly, and if the extrusion temperature exceeds 220 ℃ It may cause deterioration of properties due to discoloration and carbonization. Extrusion temperature of the starch and kneading compounding process of the second step in the process is carried out in the range of 150 to 200 ℃, more preferably in the temperature range of 150 to 180 ℃. If the extrusion temperature is less than 150 ℃, the viscosity of the resin is increased and the dispersibility of the starch may be lowered, which may cause a decrease in the physical properties of the film, and the carbonization of starch occurs at 200 ℃ or more, discoloration and physical properties decrease during film production. In particular, it is important to remove the gas generated from starch moisture and additives by applying a vacuum of less than 10 torr during starch and compounding process, which is the final stage of extrusion. Otherwise, foaming of resin may occur, resulting in reduced productivity and physical properties. The degradation may be caused. A biodegradable resin film is also provided by the biodegradable resin composition produced by the present invention. The biodegradable film of the present invention may be molded into a garbage bag, a shopping bag, an industrial packaging film, an agricultural film, a disposable tablecloth and a rollback, and may also contribute to preventing environmental pollution by completely biodegrading carbon dioxide and water by microorganisms in a natural state. will be.

Hereinafter, the present invention is described in more detail by the following examples and comparative examples. However, the present embodiment is only illustrative for the purpose of understanding and does not limit the present invention.

Example  One

4 kg of EnPol G8060, a biodegradable aliphatic / aromatic copolyester, and 3 kg of NatureLactus's polylactic acid 2002D, 4 g of high-temperature initiator tert-butylperbenzoate were added using a super mixer. After mixing for 2 minutes, the feeder was introduced into the main hopper using a twin screw extruder as shown in FIG. 1 having a screw of diameter φ70 at a working temperature of 210 ° C., and simultaneously 2 kg of corn starch and 200 g of starch plasticizer through a side hopper. , 8 g of alum starch, a starch structure breaker, and 80 g of ethylene vinyl acetate, a compatibilizer, were sufficiently mixed in a ribbon mixer for 5 minutes, and then pellets were prepared by extruding the resin at a rotational speed of 200 rpm under a vacuum of 10 Torr or less. Next, the obtained pellets were dried in a hot air dryer, and after 12 hours, a blown film molding machine was used to produce a 20 μm film. The obtained film was checked for mechanical properties of tensile strength, tear strength, and bonding strength by using a universal testing machine, and the results are shown in Table 1.

Example  2

4 kg of EnPol G8060, a biodegradable aliphatic / aromatic copolyester, and 4 kg of Polylactic acid 2002D from Natureworks, 8 g of high-temperature initiator tert-butylperbenzoate, 40 g of PE-wax with lubricant, and slip oleore 4 g of amide was mixed for 3 minutes using a super mixer, and then introduced into the main hopper using a twin screw extruder as shown in FIG. 1 having a screw of diameter φ70 at a working temperature of 210 ° C. Through side hopper, 2kg of corn starch, 200g of starch plasticizer, 200g of starch plasticizer, 8g of starch structure destroyer, and 80g of ethylene vinyl acetate, which are compatibilizers, were mixed in a ribbon mixer for 5 minutes and added at a vacuum speed of 200rpm under 10 Torr. The resin was extruded to prepare pellets. Next, the obtained pellets were dried in a hot air dryer, and after 12 hours, a blown film molding machine was used to produce a 20 μm film. The obtained film was checked for mechanical properties of tensile strength, tear strength, and bonding strength by using a universal testing machine, and the results are shown in Table 1.

Comparative example  One

4 kg of EnPol G8060, a biodegradable aliphatic / aromatic copolyester, 4 kg of Polylactic acid from NatureWorks, 2002 kg of PE-wax, and 4 g of oleamide as a slip agent were added using a super mixer. After mixing for 2 minutes, it is put into the main hopper using a twin screw extruder with a screw diameter of φ70 at the working temperature of 200 ℃ and at the same time through the side hopper, 2kg of corn starch and 200g of starch plasticizer, 200g of starch structure destroyer, alum 8g, 80 g of a compatibilizer, ethylene vinyl acetate, was sufficiently mixed in a ribbon mixer for 5 minutes, and then extruded into a pellet at a rotational speed of 200 rpm under a vacuum of 10 Torr to prepare pellets. The obtained pellet was dried in a hot air dryer, and 12 After time, a blown film forming machine was used to produce a film of 20 mu m. The obtained film was checked for mechanical properties of tensile strength, tear strength, and bonding strength by using a universal testing machine, and the results are shown in Table 1.

Comparative example  2

Biodegradable aliphatic / aromatic copolyester 4 kg of EnPol G8060 from Nature Chemicals, 4.7 kg of polylactic acid 2002D from Natureworks, 1 kg of corn starch, 6 g of PE-wax with lubricating agent, 8 g of oleamide as slip agent, 50 g of glycerin as starch plasticizer 5g of alum, which is a starch structure destroyer, and 300g of polyvinyl alcohol as a compatibilizer are mixed sufficiently for 5 minutes using a super mixer, and then used in a twin screw extruder having a diameter of 70 mm at a working temperature of 180 ° C. The pellet was prepared by extruding the resin at a rotational speed of 200 rpm under vacuum.

Next, the obtained pellet was dried for 12 hours by hot air drying, and a 20 μm film was prepared using a blown film forming machine. The universal tester confirmed the mechanical properties of tensile strength, tear strength, and bonding strength, and the results are shown in Table 1 below. Indicated.

Comparative example  3

Biodegradable aliphatic / aromatic copolyester, 5 kg of EnPol G8060 from Nature Chemicals, 5 kg of polylactic acid from Natureworks 2002D, 50 g of PE-wax with lubricant, and 5 g of oleamide as slipper After sufficiently mixing for a minute, a pellet was manufactured by extruding the resin at a rotational speed of 200 rpm under a vacuum of 10 Torr or less using a twin screw extruder having a screw of diameter 70 at a working temperature of 180 ° C.

Next, the obtained pellets were vacuum dried for 12 hours, and 20 탆 films were prepared using a blown film molding machine. The universal properties test machine was used to check the mechanical properties of tensile strength, tear strength, and bonding strength, and the results are shown in Table 1 below. Indicated.

Table 1.

Tensile strength (kgf / cm2) Tear strength (kgf / cm2) Bond strength (kgf / 15mm) TD MD TD MD Example 1 520 590 350 250 1.30 Example 2 510 580 340 240 1.20 Comparative Example 1 420 460 180 150 0.93 Comparative Example 2 400 440 170 140 1.15 Comparative Example 3 470 500 120 110 0.87

TD: longitudinal direction of blown film, MD: transverse direction of blown film

In the above embodiment, the tensile strength is the test method of KS M 3509, and the tear strength is the test method of KS M 3509 using a universal testing machine at a temperature of 23 ° C. and a relative humidity of 50% at a speed of 500 mm / min. Bonding strength was measured by the method of KS M7132.

As can be seen from Table 1, the biodegradable resin composition (Example 1) containing polylactic acid, aliphatic / aromatic copolyester and starch prepared using a high temperature initiator was prepared without using a high temperature initiator. It can be seen that the mechanical properties (tensile strength, tear strength, bond strength) are excellent compared to the resin of 3.

Test Example  One

Changes in Physical Properties of Films of Biodegradable Resin Compositions with High Temperature Initiator Content

To determine the optimal content range of the hot initiator, vary the amount of hot initiator added as shown in Table 2 below, starch (20%) biodegradable aliphatic / aromatic copolyester (40%) and polylactic acid (40%) The fixed ratio was fixed and film property specimens were prepared as shown in Example 1, and tensile strength, tear strength, and bonding strength were measured. The measurement results are summarized in Table 2 below.

Table 2.

Properties of high temperature initiator Tensile strength (kgf / cm ² ) Tear strength (kgf / cm ² ) Bond strength (kgf / 15mm) TD MD TD MD 0.005% 420 480 240 230 1.1 0.1% 460 490 250 240 1.0 0.5% 510 550 300 280 1.2 1.0% 530 580 360 310 1.3 2.0% 520 575 350 320 1.27

As can be seen from the results shown in Table 2, when the content of the high-temperature initiator is less than 0.1 parts by weight, there is almost no physical property improvement effect of the film, and when the content of 2.0 parts by weight or more does not increase proportionally.

Test Example  2

In order to examine the biodegradability of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3, a 20 μm film was tested for 3 months by weight loss of the sample through landfilling. After landfilling, the samples were taken and the foreign matters were removed from the sample with water and alcohol, and the biodegradation rate was measured by dividing the weight after landfilling by the weight before landfilling. At this time, the reclamation was carried out to a depth 30 cm that can coexist aerobic microorganisms and anaerobic microorganisms in the nearby mountain. The measurement results are as follows.

Table 3.

division Biodegradability (% of weight loss) Example 1 98.0 Example 2 99.7 Example 3 96.8 Comparative Example 1 98.5 Comparative Example 2 94.2 Comparative Example 3 83.0

As can be seen from Table 3, in the case of the film containing starch, after 3 months, all the specimens were completely decomposed as in the result of Example 1 to Comparative Example 2, and in the case of Comparative Example 3 containing no starch The decomposition rate was slow.

1 is a schematic view of a twin screw extruder.

Claims (10)

A biodegradable resin composition comprising 10 to 40 parts by weight of aliphatic / aromatic copolyester resin and 10 to 50 parts by weight of polylactic acid, aliphatic / aromatic copolyester resin and polylactic acid based on 100 parts by weight of biodegradable resin composition 100 0.01 to 2.0 parts by weight of peroxide-based high temperature initiator, 10 to 50 parts by weight of starch based on 100 parts by weight of biodegradable resin composition, and 1 to 10 parts by weight of starch plasticizer, based on 100 parts by weight of starch, 0.1 parts by weight. A biodegradable resin composition comprising to 5 parts by weight of starch structure breaker and 0.1 to 3.0 parts by weight of compatibilizer. The biodegradable resin composition according to claim 1, wherein the aliphatic / aromatic copolyester resin is Enpol 8060 (chemical). The method of claim 1, wherein the peroxide high temperature initiator is di-tert-butylperoxide, di-tert-butylperoxyhexahydroterephthalate, di-tert-butylperoxy-3,3,5-trimethyl It is cyclohexane or tert- butylperbenzoate, The biodegradable resin composition characterized by the above-mentioned. The biodegradable resin composition according to claim 3, wherein the high temperature initiator of the peroxide is 0.05 to 2.0 parts by weight based on 100 parts by weight of the aliphatic polyester mixture. The starch according to claim 1, wherein the starch is corn starch, tapioca starch, potato starch, wheat starch, and alpha starch, oxidized starch, acid treated starch, acetyladipic acid starch, and octenyl succinate starch as rice starch and modified starch. And a mixture of two or more thereof. The biodegradable resin composition according to claim 1, wherein the compatibilizer is any one selected from glycidyl methacrylate, ethylene vinyl alcohol, polyvinyl alcohol, and ethylene vinyl acetate. A method for producing a biodegradable resin composition, comprising 10 to 40 parts by weight of aliphatic / aromatic copolyester resin, 10 to 50 parts by weight of polylactic acid, and aliphatic / aromatic copolyester resin based on 100 parts by weight of biodegradable resin composition Mixing 0.01 to 2.0 parts by weight of the peroxide-based high temperature initiator in a mixer to produce a first mixture based on 100 parts by weight of the mixture of polylactic acid, first extruding the resulting first mixture, to the resulting extrusion mixture 10 to 50 parts by weight of starch and 0.1 to 3.0 parts by weight of compatibilizer based on 100 parts by weight of biodegradable resin composition, and 1 to 10 parts by weight of starch plasticizer and 0.1 to 5 parts by weight of starch structure breaker based on 100 parts by weight of starch Adding and mixing to form a second mixture, and the second mixture under vacuum of 10 torr or less A method for preparing the biodegradable resin composition of claim 1, comprising the step of second extrusion. The method of claim 7, wherein the first extrusion is performed in the range of 180 to 220 ° C. and the second extrusion is performed at 150 to 200 ° C. 9. A biodegradable film made of the biodegradable resin composition according to claim 1. The biodegradable film according to claim 9, which is a garbage bag, a shopping bag, a food packaging film, an industrial packaging film, an agricultural film, a disposable tablecloth or a rollback.

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