KR20230170586A - Biodegradable compositiom and biodegradable film - Google Patents

Abstract

In the present invention, a biodegradable composition comprising polybutylene adipate terephthalate (PBAT) and polybutylene adipate terephthalate (PBAT) in which maleic acid is ester bonded to the hydroxy group (-OH) at the terminal, and biodegradable composition. Sex films are provided.

Description

Biodegradable composition and biodegradable film {BIODEGRADABLE COMPOSITIOM AND BIODEGRADABLE FILM}

The present invention relates to biodegradable compositions and biodegradable films.

Recently, as interest in environmental protection and eco-friendliness has rapidly increased, the need for methods of growing eco-friendly agricultural products is increasing. Mulching is known as one of these eco-friendly farming methods. When growing crops, the surface of the soil is covered with a mulching film to prevent the growth of weeds, prevent pests and diseases, maintain soil moisture or regulate ground temperature, and in case of rain. This is a method to prevent soil erosion by rainwater and reduce pesticide use.

The mulching film used in this mulching farming method greatly contributes to the productivity of agricultural products, but there are difficulties in collecting and recycling after use. Usually, synthetic resins such as polypropylene and polyethylene are used and biodegradable ingredients are added as additives to provide biodegradability, but biodegradation of the synthetic resin itself is impossible. Additionally, synthetic resins left behind without being biodegraded have the problem of contaminating the soil.

Accordingly, there have been attempts to manufacture mulching films using polybutylene adipate terephthalate (PBAT), a biodegradable plastic. However, while polybutylene adipate terephthalate (PBAT) has high elongation, mechanical properties such as Young's modulus have been There are fewer problems compared to films such as polyethylene. In addition, polybutylene adipate terephthalate (PBAT) is a 100% petroleum-based material, so it has a low bio-material content.

Accordingly, attempts have been made to improve the physical properties and increase the content of bio-based materials by compounding various biodegradable materials with polybutylene adipate terephthalate (PBAT), but there is a difference between polybutylene adipate terephthalate and other biodegradable materials. There is a problem with low tensile properties due to low compatibility.

The present invention is intended to provide a biodegradable composition and a biodegradable film with excellent tensile properties such as tear strength, maximum tensile strength, elongation at break, and Young's modulus, and with an increased content of bio raw materials.

According to one embodiment of the present invention, polybutylene adipate terephthalate (PBAT); and polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to a terminal hydroxy group (-OH).

Additionally, according to one embodiment of the present invention, polybutylene adipate terephthalate (PBAT); and polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to a terminal hydroxy group (-OH).

Hereinafter, the biodegradable composition and biodegradable film according to specific embodiments of the invention will be described in more detail.

Throughout this specification, unless otherwise specified, “include” or “contains” refers to the inclusion of a certain component (or component) without particular limitation, excluding the addition of other components (or components). cannot be interpreted as

Throughout this specification, “polylactic acid prepolymer” refers to polylactic acid with a weight average molecular weight of 1,000 to 50,000 g/mol, which is obtained by oligomerizing lactic acid.

Throughout this specification, “poly(3-hydroxypropionate) prepolymer” refers to poly(3-hydroxypropionate) with a weight average molecular weight of 1,000 to 50,000 g/mol obtained by oligomerizing 3-hydroxypropionate. it means.

In addition, unless otherwise stated herein, the weight average molecular weight of polylactic acid prepolymer, poly(3-hydroxypropionate) prepolymer, and copolymer can be measured using gel permeation chromatography (GPC). . Specifically, the prepolymer or copolymer is dissolved in chloroform to a concentration of 2 mg/ml, then 20 μl is injected into GPC, and GPC analysis is performed at 40°C. At this time, the mobile phase of GPC uses chloroform and flows at a flow rate of 1.0 mL/min, the column uses two Agilent Mixed-Bs connected in series, and the detector uses an RI Detector. The Mw value is derived using a calibration curve formed using a polystyrene standard specimen. The weight average molecular weights of the polystyrene standard specimens were 2,000 g/mol, 10,000 g/mol, 30,000 g/mol, 70,000 g/mol, 200,000 g/mol, 700,000 g/mol, 2,000,000 g/mol, 4,000,000 g/mol, and 10,000,000. Nine types of g/mol were used.

Additionally, in this specification, the term “substituted or unsubstituted” refers to deuterium; halogen group; Nitrile group; nitro group; hydroxyl group; carbonyl group; ester group; imide group; amino group; Phosphine oxide group; Alkoxy group; Aryloxy group; Alkylthioxy group; Arylthioxy group; Alkyl sulphoxy group; Aryl sulfoxy group; silyl group; boron group; Alkyl group; Cycloalkyl group; alkenyl group; Aryl group; Aralkyl group; Aralkenyl group; Alkylaryl group; Alkylamine group; Aralkylamine group; heteroarylamine group; Arylamine group; Arylphosphine group; or substituted or unsubstituted with one or more substituents selected from the group consisting of heterocyclic groups containing one or more of N, O and S atoms, or substituted or unsubstituted with two or more of the above-exemplified substituents linked. . For example, “a substituent group in which two or more substituents are connected” may be a biphenyl group. That is, the biphenyl group may be an aryl group, or it may be interpreted as a substituent in which two phenyl groups are connected.

Polybutylene adipate terephthalate can be compounded with other biodegradable materials, such as thermoplastic starch, to prepare a composition for making biodegradable films; polybutylene adipate terephthalate is hydrophobic, whereas thermoplastic starch is hydrophobic. Since polybutylene adipate terephthalate and thermoplastic starch do not mix well, there is a problem in that compatibility is reduced because it is hydrophilic.

In response to this, the present inventors found that when 'polybutylene adipate terephthalate with maleic acid ester bonded to the terminal hydroxy group' was used as a compatibilizer in a biodegradable composition containing polybutylene adipate terephthalate, compatibility was improved. The present invention was completed by finding that the mechanical properties, such as tensile strength, of biodegradable films manufactured with this composition were improved.

In addition, as the content of thermoplastic starch increases in the biodegradable composition containing polybutylene adipate terephthalate, it has the advantage of being economical due to lower price, improving biodegradability, and increasing the content of bio-based carbon. As the biodegradable composition uses 'polybutylene adipate terephthalate in which maleic acid is ester bonded to a terminal hydroxy group' as a compatibilizer, the above-described effect can be achieved by including a large amount of the thermoplastic starch.

According to one embodiment of the invention, polybutylene adipate terephthalate (PBAT); and polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to a terminal hydroxy group (-OH).

The ‘polybutylene adipate terephthalate in which maleic acid is ester bonded to the terminal hydroxy group’ can be used as a compatibilizer to improve the compatibility of biodegradable compositions. In addition, ‘polybutylene adipate terephthalate, in which maleic acid is ester bonded to the hydroxy group at the end,’ acts as a chain extender and can increase molecular weight, increase melt viscosity, and improve formability such as stretchability.

The ‘polybutylene adipate terephthalate in which maleic acid is ester bonded to the terminal hydroxy group’ can be produced by esterifying maleic acid and/or maleic anhydride to the terminal hydroxy group of polybutylene adipate terephthalate. At this time, the maleic anhydride may have a higher ester reaction reactivity with polybutylene adipate terephthalate than the maleic acid.

For example, polybutylene adipate terephthalate, in which maleic acid is ester bonded to the terminal hydroxy group, may be represented by the following formula (1) or (2).

[Formula 1]

[Formula 2]

In Formulas 1 and 2,

a to d may each independently be an integer of 1 to 500, 5 to 450, 10 to 400, or 20 to 300.

'Polybutylene adipate terephthalate in which maleic acid is ester bonded to the terminal hydroxy group' represented by Formula 1 is an ester bond formed by ester reaction of one carboxyl group contained in maleic acid with the terminal hydroxy group of polybutylene adipate terephthalate. It may have happened. In addition, 'polybutylene adipate terephthalate in which maleic acid is ester bonded to the hydroxyl group at the terminal' represented by the formula 2 is a polybutylene adipate terephthalate in which the two carboxyl groups contained in maleic acid are different from the hydroxyl group at the terminal of the polybutylene adipate terephthalate and the ester. It may be ester bonded through reaction.

Polybutylene adipate terephthalate, in which maleic acid is ester bonded to the terminal hydroxy group, can be prepared by esterifying maleic acid and/or maleic anhydride with polybutylene adipate terephthalate, as described above. Maleic acid and /or by adjusting the content of maleic anhydride, the content of polybutylene adipate terephthalate, reaction temperature, reaction time, type and content of additives, etc., to produce polybutylene adipate terephthalate in which maleic acid is ester bonded to the terminal hydroxy group. Phthalate can be manufactured, and the weight average molecular weight, structure, viscosity, etc. of polybutylene adipate terephthalate, in which maleic acid is ester bonded to the terminal hydroxy group, can be controlled.

Meanwhile, in the past, there was a case of using a compatibilizer in which maleic anhydride was grafted to polybutylene adipate terephthalate, but it was difficult for radicals to form in the middle of the polybutylene adipate terephthalate chain or due to steric hinderance. While the grafting reaction efficiency is low, polybutylene adipate terephthalate, in which maleic acid is ester bonded, has the advantage of significantly higher reaction efficiency. Accordingly, when polybutylene adipate terephthalate, in which maleic acid is ester-bonded to the terminal hydroxy group, is included as a compatibilizer in biodegradable compositions and films, when a conventional compatibilizer in which maleic anhydride is graft-bonded is used. Compared to this, tensile properties such as tear strength, ultimate tensile strength, elongation at break, and Young's modulus may be superior.

In the biodegradable composition according to the above embodiment, the polybutylene adipate terephthalate, in which maleic acid is ester bonded to the terminal hydroxy group, is included in an amount of 0.5% by weight or more and 10.0% by weight or less based on a total of 100% by weight of solid content of the biodegradable composition. can do. For example, with respect to the total solid content of the biodegradable composition of 100% by weight, polybutylene adipate terephthalate, in which maleic acid is ester bonded to the terminal hydroxy group, is added in an amount of 0.7% by weight or more, 0.9% by weight or more, 1.0% by weight or more, or 2.0% by weight. % or more, and may include 9.0 wt% or less, 7.0 wt% or less, 6.0 wt% or less, and 5.0 wt% or less. If too little polybutylene adipate terephthalate, in which maleic acid is ester bonded to the hydroxyl group at the terminal, is included, the effect of improving compatibility may not be achieved, and the mechanical properties such as tensile strength of the film made from the composition may be reduced, and the terminal If too much polybutylene adipate terephthalate, in which maleic acid is ester bonded to the hydroxy group, is included, the melt viscosity may increase excessively and the moldability may deteriorate.

In addition, the biodegradable composition according to the above embodiment may further include polyhydroxyalkanoate. The polyhydroxyalkanoate is not limited thereto, but includes poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(2-hydroxypropionate), and poly(3-hydroxypropionate). nate) may be poly(3-hydroxyvalate), poly(4-hydroxyvalate) or poly(5-hydroxyvalate), but in order to improve the tensile properties of the film using the biodegradable composition, the poly The hydroxyalkanoate is preferably poly(3-hydroxypropionate).

In addition, the polyhydroxyalkanoate has a weight average molecular weight (Mw) measured using gel permeation chromatography (GPC) of 50,000 to 300,000 g/mol, and more specifically, 50,000 g/mol or more. , 70,000 g/mol or more, or 100,000 g/mol or more, and has a weight average molecular weight of 300,000 g/mol or less, or 200,000 g/mol or less, or 150,000 g/mol or less. If the weight average molecular weight of the polyhydroxyalkanoate is too small, the overall mechanical properties may be significantly reduced, and if the weight average molecular weight is too large, the process may be difficult and processability and elongation may be low.

In addition, the biodegradable composition may contain 3 to 40% by weight of the polyhydroxyalkanoate based on the total solid content of 100% by weight of the biodegradable composition, more specifically, 3% by weight or more, 5% by weight or more, It may be included in an amount of 7% by weight or more, 40% by weight or less, 35% by weight or less, and 30% by weight or less. If the polyhydroxyalkanoate is included in an excessively small amount in the biodegradable composition, the tensile properties such as Young's modulus and yield tensile strength of the film produced may be reduced, and if the polyhydroxyalkanoate is excessively contained in the biodegradable composition, If it is included in large quantities, the elongation of the film produced may be lowered.

Additionally, the biodegradable composition according to the above embodiment may further include a hydroxyalkanoate-lactide copolymer.

The hydroxyalkanoate-lactide copolymer may be a block copolymer including one or more polyhydroxyalkanoate (PHA) blocks and one or more polylactic acid blocks. As the hydroxyalkanoate-lactide copolymer contains the above-mentioned blocks, it can exhibit the environmental friendliness and biodegradability of polyhydroxyalkanoate and polylactic acid.

The hydroxyalkanoates include 3-hydroxybutyrate, 4-hydroxybutyrate, 2-hydroxypropionate, 3-hydroxypropionate, and (D)-3- having a medium chain length of 6 to 14 carbon atoms. It may be hydroxycarboxylate, 3-hydroxyvalate, 4-hydroxyvalate or 5-hydroxyvalate. Therefore, the hydroxyalkanoate-lactide copolymer is 3-hydroxybutyrate-lactide copolymer, 4-hydroxybutyrate-lactide copolymer, 2-hydroxypropionate-lactide copolymer, 3- It may be a hydroxypropionate-lactide copolymer, a 4-hydroxyvalate-lactide copolymer, or a 5-hydroxyvalate-lactide copolymer, for example, the hydroxyalkanoate-lactide. The copolymer may be a 3-hydroxypropionate-lactide copolymer to improve flexibility and mechanical properties.

The 3-hydroxypropionate-lactide copolymer may be a block copolymer obtained by polymerizing polylactic acid prepolymer and poly(3-hydroxypropionate) prepolymer.

The 3-hydroxypropionate-lactide copolymer exhibits the excellent tensile strength and elastic modulus characteristics of the polylactic acid prepolymer, while the poly(3-hydroxypropionate) prepolymer has a glass transition temperature (Tg). By increasing flexibility by lowering and improving mechanical properties such as impact strength, it is possible to prevent the brittleness of polylactic acid due to its poor elongation.

The polylactic acid prepolymer may be manufactured by fermentation or polycondensation of lactic acid.

The polylactic acid prepolymer may have a weight average molecular weight of 1,000 g/mol or more, or 5,000 g/mol or more, or 6,000 g/mol or more, or 8,000 g/mol or more, and 50,000 g/mol or less, or 30,000 g/mol or less, When it is desired to increase the crystallinity of the block containing repeating units derived from polylactic acid prepolymer in the final manufactured block copolymer, the polylactic acid prepolymer must be greater than 20,000 g/mol, or 22,000 g/mol or more, or 23,000 g/mol. It is preferable to have a high weight average molecular weight of more than or equal to 25,000 g/mol, and less than or equal to 50,000 g/mol, or less than or equal to 30,000 g/mol, or less than or equal to 28,000 g/mol, or less than or equal to 26,000 g/mol.

If the weight average molecular weight of the polylactic acid prepolymer is less than 20,000 g/mol, the polymer crystals are small and it is difficult to maintain the crystallinity of the polymer in the final manufactured block copolymer. If the weight average molecular weight of the polylactic acid prepolymer exceeds 50,000 g/mol, it is difficult to maintain the crystallinity of the polymer. During polymerization, the side reaction rate occurring within the prepolymer chain becomes faster than the reaction rate between polylactic acid prepolymers.

Meanwhile, 'lactic acid' used in the present invention refers to L-lactic acid, D-lactic acid, or a mixture thereof.

The poly(3-hydroxypropionate) prepolymer may be manufactured by fermenting or condensation polymerization of 3-hydroxypropionate.

The weight average molecular weight of the poly(3-hydroxypropionate) prepolymer is 1,000 g/mol or more, or 5,000 g/mol or more, or 8,000 g/mol or more, or 8,500 g/mol or more, and 50,000 g/mol or less, Alternatively, it may be 30,000 g/mol or less, and when it is desired to increase the crystallinity of the repeating unit derived from the poly(3-hydroxypropionate) prepolymer in the final manufactured block copolymer, the poly(3-hydroxypropionate) The prepolymer has a high weight average molecular weight of more than 20,000 g/mol, or more than 22,000 g/mol, or more than 25,000 g/mol, and less than or equal to 50,000 g/mol, or less than or equal to 30,000 g/mol, or less than or equal to 28,000 g/mol. desirable.

As explained in the polylactic acid prepolymer, if the weight average molecular weight of the poly(3-hydroxypropionate) prepolymer is 20,000 g/mol or less, the polymer crystals are small, making it difficult to maintain the crystallinity of the polymer in the final manufactured block copolymer. It is difficult, and if the weight average molecular weight of the poly(3-hydroxypropionate) prepolymer exceeds 50,000 g/mol, the side reaction rate occurring inside the prepolymer chain is higher than the reaction rate between poly(3-hydroxypropionate) prepolymers during polymerization. becomes faster.

That is, at least one of the polylactic acid prepolymer and the poly(3-hydroxypropionate) prepolymer may have a weight average molecular weight of more than 20,000 g/mol and less than or equal to 50,000 g/mol.

Meanwhile, the lactic acid and 3-hydroxypropionate may be plastic and biodegradable compounds produced from renewable sources by microbial fermentation, and polylactic acid prepolymer and poly(3-hydroxypropionate) formed by polymerizing them The block copolymer containing the prepolymer may also exhibit environmental friendliness and biodegradability. For this reason, the biodegradable composition and biodegradable film containing the block copolymer may contain a large amount of bio raw materials while exhibiting environmental friendliness and biodegradability.

The 3-hydroxypropionate-lactide copolymer is a block copolymer in which polylactic acid prepolymer and poly(3-hydroxypropionate) prepolymer are polymerized, and in the block copolymer, the polylactic acid prepolymer and poly(3 -Hydroxypropionate) The weight ratio of the prepolymer is 95:5 to 50:50, 90:10 to 55:45, 90:10 to 60:40, 90:10 to 70:30, or 90:10 to 80:20. It can be. If too little of the poly(3-hydroxypropionate) prepolymer is included in the polylactic acid prepolymer, brittleness may increase, and the poly(3-hydroxypropionate) prepolymer may increase brittleness. If too much prepolymer is included, the molecular weight may be lowered and processability and heat stability may be reduced.

As described above, the 3-hydroxypropionate-lactide copolymer includes one or more poly(3-hydroxypropionate) blocks and one or more polylactic acid blocks, and exhibits high crystallinity. You can.

For example, the 3-hydroxypropionate-lactide copolymer has a poly in the copolymer calculated according to the following equations 1 and 2 using the crystallization temperature and melting temperature measured through differential scanning calorimetry. The crystallinity of the lactic acid block ( _{Xc_PLA} ) may be greater than 0 and 50 or less, or the crystallinity of the poly(3-hydroxypropionate) block ( _{Xc_P(3HP)} ) may be 0 to 50, or greater than 0 and 50 or less.

In addition, the total sum of the crystallinity degree of the polylactic acid block and the crystallinity degree of the poly(3-hydroxypropionate) block in the copolymer is 20 to 100, more specifically, 20 or more, or 30 or more, or 32 or more, It may be 100 or less, or 70 or less, or 50 or less, or 48 or less.

As the copolymer satisfies the above-mentioned degree of crystallinity, flexibility and mechanical properties can be well balanced and improved, and it can simultaneously exhibit the excellent strength characteristics of polylactic acid and the excellent elongation characteristics of poly(3-hydroxypropionate).

On the other hand, if the total crystallinity degree is too high, biodegradability and processability may be reduced, and if the total crystallinity degree is too low, the strength may be reduced.

[Equation 1]

Crystallinity of polylactic acid block ( _{Xc_PLA} )= [(PLA Tm area)-(PLA Tcc area)]/93.7

In Equation 1, the PLA Tm area is the integral value of the peak at the melting temperature (Tm) of the polylactic acid (PLA) block in the block copolymer measured through differential scanning calorimetry, and the PLA Tcc area is the differential scanning area. It may be the integral value of the peak at the crystallization temperature (Tcc) of the polylactic acid block in the block copolymer measured through calorimetric analysis.

[Equation 2]

Crystallinity of poly(3-hydroxypropionate) block (Xc_ _P(3HP) )= [(P(3HP) Tm area)-(P(3HP) Tcc area)]/64

In Equation 2, the P(3HP) Tm area is the melting temperature (Tm) of the poly(3-hydroxypropionate) (P(3HP)) block in the block copolymer measured through differential scanning calorimetry. is the integral value for the peak, and the P(3HP) Tcc area is the integral for the peak at the crystallization temperature (Tcc) of the poly(3-hydroxypropionate) block in the block copolymer measured through differential scanning calorimetry. It can be a value.

In addition, the integrated value for the peaks at Tm and Tcc means a value obtained by integrating the lower areas of the peaks representing Tm and Tcc, respectively.

At this time, differential scanning calorimetry for measuring Tm and Tcc of each block can be performed using PerkinElmer DSC800 equipment. In addition, the sample to be analyzed was heated at a rate of 10°C per minute from 25°C to 250°C under a nitrogen atmosphere, cooled again from 250°C to -50°C at a rate of -10°C per minute, and then again from -50°C to 250°C. By increasing the temperature at a rate of 10°C per minute and obtaining an endothermic curve, Tm and Tcc can be confirmed.

The hydroxyalkanoate-lactide copolymer has a weight average molecular weight (Mw) measured using gel permeation chromatography (GPC) of 50,000 to 300,000 g/mol, and more specifically, 50,000 g/mol. mol or more, 70,000 g/mol or more, or 100,000 g/mol or more, and has a weight average molecular weight of 300,000 g/mol or less, or 200,000 g/mol or less, or 150,000 g/mol or less. If the weight average molecular weight of the hydroxyalkanoate-lactide copolymer is too small, the overall mechanical properties may be significantly reduced, and if the weight average molecular weight is too large, the process may be difficult and processability and elongation may be low.

The biodegradable composition according to one embodiment includes the hydroxyalkanoate-lactide copolymer, for example, may be included in 3 to 40% by weight based on the total solid content of 100% by weight of the biodegradable composition, and more specifically It may be included in an amount of 3% by weight or more, 5% by weight or more, or 7% by weight or less, or 40% by weight or less, 35% by weight or less, and 30% by weight or less.

If the hydroxyalkanoate-lactide copolymer is included in an excessively small amount in the biodegradable composition, the tensile properties such as Young's modulus and yield tensile strength of the film produced therefrom may be reduced, and the hydroxyalkanoate-lactide copolymer may be reduced. If too much copolymer is included in the biodegradable composition, the elongation of the film produced therefrom may be lowered.

The biodegradable composition according to the above embodiment includes polybutylene adipate terephthalate (PBAT).

The polybutylene adipate terephthalate (PBAT) is a biodegradable resin and may be included in an amount of 30 to 80% by weight based on 100% by weight of the total solid content of the biodegradable composition, and more specifically, 30% by weight or more, 35% by weight or more, 40% by weight or more. It may be included in weight% or more, 80% by weight or less, 75% by weight or less, and 70% by weight or less.

If too little polybutylene adipate terephthalate (PBAT) is included in the biodegradable composition, the elongation of the film manufactured using it may be lowered, and the polybutylene adipate terephthalate (PBAT) may be included in the biodegradable composition. If it is included in excessive amounts, the tensile properties, such as Young's modulus and yield tensile strength, of films manufactured using it may be reduced.

The weight ratio of the hydroxyalkanoate-lactide copolymer and polybutylene adipate terephthalate (PBAT) contained in the biodegradable composition according to the embodiment is 5:95 to 50:50, 5:95 to 40. :60, 10:90 to 30:70.

If too little polybutylene adipate terephthalate (PBAT) is included compared to the hydroxyalkanoate-lactide copolymer, the elongation may be lowered, and compared to the hydroxyalkanoate-lactide copolymer, the polybutylene adipate terephthalate (PBAT) may be lowered. If too much butylene adipate terephthalate (PBAT) is included, tensile properties such as Young's modulus and yield tensile strength may decrease.

The biodegradable composition according to the above embodiment may include thermoplastic starch.

The biodegradable composition is used to increase the processability of polybutylene adipate terephthalate and to speed up the biodegradation rate. It may further contain thermoplastic starch.

The thermoplastic starch may be a starch in which a plasticizer is added to starch, a natural polymer, to give thermoplasticity that allows the shape to be freely changed without being carbonized above a certain temperature, like existing general-purpose resins such as polyethylene, polystyrene, and polypropylene.

The thermoplastic starch may include one or more selected from the group consisting of rice starch, wheat starch, corn starch, sweet potato starch, potato starch, tapioca starch, cassava starch, and modified starches thereof.

Additionally, the plasticizer included in starch, a natural polymer, may be one or more selected from the group consisting of isosorbide, glycerol, sorbitol, fructose, formamide, xylitol, corn oil, and edible oil.

The plasticizer may be included in an amount of 5% to 50% by weight, 10% to 45% by weight, or 15% to 35% by weight based on the total 100% by weight of the thermoplastic starch.

The thermoplastic starch may be included in an amount of 10 to 70% by weight based on 100% by weight of the total solid content of the biodegradable composition, and more specifically, 10% by weight or more, 15% by weight or more, 20% by weight or more, or 70% by weight or less, 60% by weight. % or less, and may be included in 50% by weight or less.

If the thermoplastic starch is included in an excessively small amount in the biodegradable composition, the biodegradation rate may be slowed and the tensile properties such as Young's modulus and yield tensile strength of films using the same may be reduced, and if the thermoplastic starch is contained in an excessive amount in the biodegradable composition, The elongation of the film using this may be lowered.

The weight ratio of the thermoplastic starch and polybutylene adipate terephthalate (PBAT) included in the biodegradable composition according to the embodiment is 5:95 to 50:50, 5:95 to 40:60, and 10:90 to 30. :It could be 70.

If too little polybutylene adipate terephthalate (PBAT) is included compared to the thermoplastic starch, the elongation may be lowered, and if too much polybutylene adipate terephthalate (PBAT) is included compared to the thermoplastic starch, the biodegradation rate may be reduced. may be delayed and tensile properties such as Young's modulus and yield tensile strength may decrease.

The biodegradable composition according to the above embodiment may include hydrophobic polybutylene adipate terephthalate and hydrophilic thermoplastic starch, and whether their compatibility is improved is determined by examining polybutylene adipate terephthalate. When the dispersed phase of the thermoplastic starch is dispersed on the phthalate matrix, compatibility can be considered to be improved as the dispersed phase of the thermoplastic starch is distributed more densely and uniformly. In addition, whether compatibility is improved, it can be seen that as the adhesive force at the interface between polybutylene adipate terephthalate and thermoplastic starch becomes stronger, their compatibility improves. In other words, the more dense and uniform the dispersed phase of thermoplastic starch is distributed on the polybutylene adipate terephthalate matrix, the better the compatibility, and the stronger the adhesive force at the interface between polybutylene adipate terephthalate and thermoplastic starch, the better the compatibility. It can be said that it has been done.

In addition, whether compatibility is improved can be numerically confirmed through analysis using a polymer viscoelastic analyzer (DMA; Dynamic Mechanical Analyzer) device, for example, the glass transition of thermoplastic starch and polybutylene adipate terephthalate. Temperature (Tg) can be measured using a polymer viscoelastic analyzer (DMA; Dynamic Mechanical Analyzer) to determine whether compatibility is improved.

Specifically, the more densely and uniformly the dispersed phase of the thermoplastic starch is distributed on the polybutylene adipate terephthalate matrix, the lower the glass transition temperature (Tg) of the thermoplastic starch. The glass transition temperature of the thermoplastic starch is measured using a polymer viscoelasticity analyzer. Through analysis, you can check whether compatibility has improved. In addition, the stronger the adhesion at the interface between polybutylene adipate terephthalate and thermoplastic starch, the more effectively the dispersed phase of thermoplastic starch transfers stress to polybutylene adipate terephthalate, increasing the glass transition temperature (Tg) of polybutylene adipate terephthalate. ), in particular, the glass transition temperature (Tg) of the butylene-adipate repeating unit, which is a soft segment, increases. The glass transition temperature of polybutylene adipate terephthalate is analyzed through a polymer viscoelasticity analyzer to determine compatibility. You can check whether there is improvement.

Therefore, the better the compatibility between polybutylene adipate terephthalate and thermoplastic starch, the lower the glass transition temperature (Tg) of the thermoplastic starch. For example, the glass transition temperature (Tg) of thermoplastic starch is 10 ℃ or more and 140 ℃ or less. , 15 ℃ or higher and 120 ℃ or lower, 20 ℃ or higher and 100 ℃ or lower, 25 ℃ or higher and 80 ℃ or lower, 25 ℃ or higher and 50 ℃ or lower, or 25 ℃ or higher and 40 ℃ or lower.

In addition, the better the compatibility between polybutylene adipate terephthalate and thermoplastic starch, the higher the glass transition temperature (Tg) of polybutylene adipate terephthalate, for example, the glass transition temperature of polybutylene adipate terephthalate. (Tg) may be -23.0 ℃ or higher and -10.0 ℃ or lower, or -22.5 ℃ or higher and -15.0 ℃ or lower.

In addition, the absolute value of the difference in glass transition temperature (Tg) of the thermoplastic starch and polybutylene adipate terephthalate is 20 ℃ or more and 70 ℃ or less, 25 ℃ or more and 65 ℃ or less, 30 ℃ or more and 60 ℃ or less, or 35 ℃. It may be above 59℃ or below.

According to one embodiment of the present invention, polybutylene adipate terephthalate (PBAT); and polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to a terminal hydroxy group (-OH).

The manufacturing method of the biodegradable film is not particularly limited, but can be obtained by using the biodegradable composition according to the above embodiment, using existing film manufacturing methods such as the known inflation method, tubular method, and T die casting method. there is. For example, the composition may be pelletized and the pellets dried at 60 to 100° C. for 6 hours or more to control the moisture content to 1,200 ppm or less, 500 ppm or less, or 200 ppm or less. Thereafter, the pelletized composite can be applied to a release film, placed in a thermocompressor, and pressure applied to produce a film. At this time, the temperature may be 130°C to 250°C, 150°C to 220°C, or 160°C to 200°C, and the pressure may be 5 MPa to 20 MPa, 8 MPa to 17 MPa, or 10 MPa to 15 MPa.

Therefore, the biodegradable film may include the same components as described above in the biodegradable composition. For example, the biodegradable film includes the polybutylene adipate terephthalate, polybutylene adipate terephthalate in which maleic acid is ester bonded to the terminal hydroxy group, the thermoplastic starch, polyhydroxypropionate, and the hydroxyl group. It may include alkanoate-lactide copolymer, etc. In addition, the polybutylene adipate terephthalate, the polybutylene adipate terephthalate in which maleic acid is ester bonded to the terminal hydroxy group, the thermoplastic starch, polyhydroxypropionate, and the hydroxyalkanoate-lactide copolymer The molecular weight, content, structure, etc. of the polymer are as described above. For example, the biodegradable film may contain 0.5% by weight or more and 10.0% by weight or less of polybutylene adipate terephthalate, in which maleic acid is ester bonded to the terminal hydroxy group, based on a total of 100% by weight of the biodegradable film. . For example, based on a total of 100% by weight of the biodegradable film, 0.7% by weight or more, 0.9% by weight, 1.0% by weight, or 2.0% by weight of polybutylene adipate terephthalate, in which maleic acid is ester bonded to the hydroxyl group at the terminal. It may contain more than 9.0% by weight, 7.0% by weight or less, 6.0% by weight or less, and 5.0% by weight or less.

The thermoplastic starch may be included in an amount of 10% by weight or more and 50% by weight or less based on 100% by weight of the biodegradable film. For example, the thermoplastic starch may be included in an amount of 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, and 45% by weight or less, 40% by weight, based on a total of 100% by weight of the biodegradable film. % or less, and may contain less than 35% by weight.

The thickness of the biodegradable film according to the above embodiment may be 10 to 300 ㎛, more specifically 10 ㎛ or more, 13 ㎛ or more, 15 ㎛ or more, 20 ㎛ or more, 20 ㎛ or more, 25 ㎛ or more, or 300 ㎛. Hereinafter, it may be 200 ㎛ or less, 150 ㎛ or less, 100 ㎛ or less, 80 ㎛ or less, and 50 ㎛ or less. When the thickness of the film is within the above-mentioned range, elasticity can be strengthened, handling properties can be excellent, and the winding state and unwinding properties of the roll can be improved. If the film thickness is too thin, the tensile strength, tear strength, and elongation may deteriorate, which may cause holes or tears in the film during use, and if the film thickness is too thick, unit price competitiveness may be reduced. The biodegradable film can be used as agricultural mulching film, disposable gloves, individual medical packaging, food packaging, garbage bags, or bags for various industrial products.

The biodegradable film according to the above embodiment may have a maximum tensile strength measured according to ASTM D882-07 of 5 MPa or more, 7 MPa or more, 8 MPa or more, or 5 MPa to 30 MPa.

The biodegradable film according to the above embodiment may have an elongation at break of 300% or more, 350% or more, 400% or more, 420% or more, 430% or more, or 300% to 700% as measured according to ASTM D882-07. .

In addition, the biodegradable film may have a Young's Modulus measured according to ASTM D882-07 of 50 MPa or more, 70 MPa or more, 74 MPa or more, 80 MPa or more, and 50 MPa to 800 MPa.

The maximum tensile strength, elongation at break, and Young's modulus of the biodegradable film, measured in MD (Machine Direction) and TD (Transverse Direction) directions, may each satisfy the above-mentioned numerical ranges.

According to the present invention, a biodegradable composition and a biodegradable film containing bio raw materials can be provided that have excellent tensile properties such as tear strength, maximum tensile strength, elongation at break, and Young's modulus while maintaining environmental friendliness and biodegradability. .

The invention is explained in more detail in the following examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

Preparation Example 1: Preparation of thermoplastic starch

Based on dry weight, 225 g of corn starch and 75 g of glycerol were mixed in a mixer and then put into an extruder for compounding. The temperature range of the extruder was 80 to 150 °C, the screw speed was set to 150 rpm, and the extruded strand was cut with a pelletizer to prepare thermoplastic starch pellets.

Preparation Example 2: Manufacture of polybutylene adipate terephthalate in which maleic acid is ester bonded to the hydroxyl group (-OH) at the end.

Add 100 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH) and 10 g of maleic acid to an internal mixer, and react at 160°C at 50 rpm for 30 minutes to form the terminal hydroxy group (- Polybutylene adipate terephthalate', in which maleic acid was ester bonded to OH), was prepared.

<Examples and Comparative Examples>

Example 1: Preparation of biodegradable film

Based on dry weight, 750 g of polybutylene adipate terephthalate (PBAT, Solpol 1000N, SOLTECH), 250 g of thermoplastic starch prepared in Preparation Example 1, and the terminal hydroxy group (-OH) prepared in Preparation Example 2 50 g of polybutylene adipate terephthalate, in which maleic acid was ester bonded, was mixed by hand and then put into an extruder for compounding. The temperature range of the extruder was 120 to 150 °C, the screw speed was set to 150 rpm, and the extruded strand was cut with a pelletizer to prepare composite pellets. The manufactured composite pellets were manufactured into a film with a thickness of 15 ㎛ at 180°C using Collin's film blown unit (BL50T).

Comparative Example 1: Production of biodegradable film

A film was prepared in the same manner as in Example 1, except that 50 g of polybutylene adipate terephthalate, in which maleic acid was ester bonded to the terminal hydroxy group (-OH) prepared in Preparation Example 2, was not used. was manufactured.

evaluation

1. Tensile property evaluation

The tensile properties of the films of Examples and Comparative Examples were evaluated according to ASTM D882-07. Tensile properties include tear strength, ultimate tensile strength, and elongation at break in MD (Machine Direction) and TD (Transverse Direction), and the results are shown in Table 1 below.

Tear strength (gf) Maximum tensile strength (MPa) Elongation at break (%) M.D. TD M.D. TD M.D. TD Example 1 765 852 20 17 524 273 Comparative Example 1 142 158 2.8 2.1 270 139

According to Table 1, it was confirmed that Example 1 was significantly superior to Comparative Example 1 in all tear strength, ultimate tensile strength, and elongation at break.

Claims (20)

polybutylene adipate terephthalate (PBAT); and
A biodegradable composition comprising polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to a terminal hydroxy group (-OH).
According to paragraph 1,
Polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to the terminal hydroxy group (-OH), is a biodegradable composition represented by the following formula 1 or 2:
[Formula 1]

[Formula 2]

In Formulas 1 and 2,
a to d are each independently an integer from 1 to 500.
According to paragraph 1,
A biodegradable composition further comprising polyhydroxyalkanoate.
According to paragraph 3,
The polyhydroxyalkanoate is poly(3-hydroxypropionate), a biodegradable composition.
According to paragraph 1,
A biodegradable composition further comprising a hydroxyalkanoate-lactide copolymer.
According to clause 5,
The biodegradable composition wherein the hydroxyalkanoate-lactide copolymer is 3-hydroxypropionate-lactide copolymer.
According to clause 6,
The 3-hydroxypropionate-lactide copolymer is a biodegradable composition that is a block copolymer obtained by polymerizing polylactic acid prepolymer and poly(3-hydroxypropionate) prepolymer.
In clause 7,
A biodegradable composition, wherein at least one of the polylactic acid prepolymer and the poly(3-hydroxypropionate) prepolymer has a weight average molecular weight of more than 20,000 g/mol and less than or equal to 50,000 g/mol.
In clause 7,
A biodegradable composition, wherein the weight ratio of the polylactic acid prepolymer and poly(3-hydroxypropionate) prepolymer is 95:5 to 50:50.
In clause 7,
The 3-hydroxypropionate-lactide copolymer has a total sum of the crystallinity degree of the polylactic acid block and the crystallinity degree of the poly(3-hydroxypropionate) block, calculated according to Equations 1 and 2 below, of 20 to 100. Phosphorus, biodegradable composition:
[Equation 1]
Crystallinity of polylactic acid block (X _{c_PLA} )= [(PLA Tm area)-(PLA Tcc area)]/93.7
(In Equation 1 above, the PLA Tm area is the integral value of the peak at the melting temperature (Tm) of the polylactic acid (PLA) block in the block copolymer measured through differential scanning calorimetry, and the PLA Tcc area is the differential This is the integrated value of the peak at the crystallization temperature (Tcc) of the polylactic acid block in the block copolymer measured through scanning calorimetry)
[Equation 2]
Crystallinity of poly(3-hydroxypropionate) block (X _{c_P(3HP)} )= [(P(3HP) Tm area)-(P(3HP) Tcc area)]/64
(In Equation 2 above, the P(3HP) Tm area is the melting temperature (Tm) of the poly(3-hydroxypropionate) (P(3HP)) block in the block copolymer measured through differential scanning calorimetry. is the integral value for the peak at, and the P(3HP) Tcc area is for the peak at the crystallization temperature (Tcc) of the poly(3-hydroxypropionate) block in the block copolymer measured through differential scanning calorimetry. (integral value)
According to clause 5,
The hydroxyalkanoate-lactide copolymer is a biodegradable composition having a weight average molecular weight of 50,000 to 300,000.
According to paragraph 1,
A biodegradable composition further comprising thermoplastic starch.
According to clause 12,
The thermoplastic starch is a biodegradable composition comprising at least one selected from the group consisting of rice starch, wheat starch, corn starch, sweet potato starch, potato starch, tapioca starch, cassava starch, and modified starches thereof.
According to clause 5,
A biodegradable composition wherein the weight ratio of the hydroxyalkanoate-lactide copolymer and polybutylene adipate terephthalate (PBAT) is 5:95 to 50:50.
According to clause 12,
A biodegradable composition, wherein the weight ratio of the thermoplastic starch and polybutylene adipate terephthalate (PBAT) is 5:95 to 50:50.
polybutylene adipate terephthalate (PBAT); and
A biodegradable film comprising polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to a terminal hydroxy group (-OH).
According to clause 16,
A biodegradable film comprising 0.1 to 10 parts by weight of polybutylene adipate terephthalate (PBAT), in which maleic acid is ester bonded to the terminal hydroxy group (-OH), based on 100 parts by weight of the biodegradable film.
According to clause 16,
The biodegradable film has a maximum tensile strength of 5 MPa or more as measured according to ASTM D882-07.
According to clause 16,
The biodegradable film has an elongation at break of 300% or more as measured according to ASTM D882-07.
According to clause 16,
The biodegradable film has a Young's modulus of 50 MPa or more as measured according to ASTM D882-07.