KR20130139690A - Polylactic acid resin composition and packaging film - Google Patents

Abstract

The present invention not only exhibits improved flexibility, but also has excellent physical properties such as mechanical properties, transparency, heat resistance, blocking resistance, and film processability, and thus may be usefully used as a packaging material. It relates to a packaging film containing.
The polylactic acid resin composition includes a hard segment including a predetermined polylactic acid repeating unit, and a soft segment including a polyurethane polyol repeating unit in which certain polyether polyol repeating units are linearly connected through a urethane bond. Polylactic acid resins having an organic carbon content (% C _bio ) of mass origin of 60% by weight or more; And a predetermined amount of antioxidant.

Description

Polylactic Acid Resin Composition and Packaging Film {POLYLACTIC ACID RESIN COMPOSITION AND PACKAGING FILM}

The present invention relates to a polylactic acid resin composition and a packaging film. More specifically, the present invention not only exhibits improved flexibility, but also has excellent physical properties such as mechanical properties, transparency, heat resistance, blocking resistance, and film processability, and thus may be usefully used as a packaging material. It relates to a resin composition and a packaging film comprising the same.

Crude oil-based resins such as polyethylene terephthalate, nylon, polyolefin, or soft polyvinyl chloride (PVC) are still widely used as materials for various applications such as packaging materials. However, such a crude oil-based resin has no biodegradability and thus has a problem of causing environmental pollution such as discharging a large amount of carbon dioxide, which is a global warming gas, during disposal. In addition, as petroleum resources have gradually become depleted, the use of biomass-based resins, typically polylactic acid resins, has been widely studied.

However, since these polylactic acid resins do not have sufficient heat resistance or mechanical properties as compared to crude oil-based resins, it is true that the polylactic acid resins have limitations in fields or applications to which they can be applied. In particular, attempts have been made to apply polylactic acid resin as a packaging material such as a packaging film, but such applications are facing limitations due to the low flexibility of the polylactic acid resin.

In order to overcome the limitations of such a polylactic acid resin, a method of adding a low molecular weight softener or plasticizer to a polylactic acid resin, or introducing a plasticizer obtained by addition polymerization of a polyether-based or aliphatic polyester- .

However, even if a packaging film or the like containing a poly (lactic acid) resin is obtained by these methods, it is a fact that there is a limit in improving the flexibility in most cases. In addition, the plasticizer or the like not only bleeds out over time, but also has a disadvantage that haze of the packaging film is increased and transparency is lowered. In addition, there have been many cases where the plasticizers and the like have lowered the mechanical properties of the packaging film. In particular, polylactic acid resins which can be easily processed by extrusion or the like, while maintaining excellent mechanical properties, have hardly been proposed. In addition, when the plasticizer or the like is added, yellowish or the like of the poly (lactic acid) resin occurs and many cases of deteriorating the external appearance of the packaging film occur.

In addition, when a plastic film or the like is introduced by a previously known method to provide a packaging film or the like containing a polylactic acid resin, a large amount of plasticizer or the like is required in order to improve flexibility, which is due to the inclusion of the polylactic acid resin. In many cases, biodegradability or eco-friendly properties were difficult to fully utilize.

In addition to this, while showing improved flexibility, it has excellent physical properties such as mechanical properties, transparency, heat resistance, blocking resistance, and film processability, and can be usefully used as a packaging material, and development of a polylactic acid resin-based packaging film having environmentally friendly characteristics This is constantly being requested.

The present invention not only exhibits improved flexibility, but also has excellent physical properties such as mechanical properties, transparency, heat resistance, blocking resistance, and film processability, which can be usefully used as a packaging material, and provides a polylactic acid resin composition having environmentally friendly characteristics. It is.

The present invention also provides a packaging film containing the polylactic acid resin composition.

The present invention includes a hard segment including a polylactic acid repeating unit of Formula 1 and a soft segment including a polyurethane polyol repeating unit in which polyether polyol repeating units of Formula 2 are linearly connected through a urethane bond. A polylactic acid resin having an organic carbon content rate (% C _bio ) of biomass origin defined by Equation 1 below 60 wt%; And

With respect to the amount of monomer added for the formation of the polylactic acid repeating unit, a polylactic acid resin composition comprising an antioxidant in an amount of 100 to 3000 ppmw is provided:

[Formula 1]

(2)

[Formula 1]

% C = _Bio (poly ¹⁴ C isotope ratio by weight of the ¹² C isotope of carbon atoms of the lactic acid resin) / ⁽¹⁴ C isotope ratio by weight of the ^bio-12 C isotope of carbon atoms of the mass origin standard)

In the general formulas (1) and (2), A is a linear or branched alkylene group having 2 to 5 carbon atoms, m is an integer of 10 to 100, and n is an integer of 700 to 5000.

The present invention also provides a packaging film comprising the polylactic acid resin composition.

Hereinafter, a polylactic acid resin composition and a packaging film including the same according to specific embodiments of the present invention will be described.

According to an embodiment of the present invention, a hard segment including a polylactic acid repeating unit of Formula 1 and a polyether polyol repeating unit of Formula 2 include a polyurethane polyol repeating unit linearly connected through a urethane bond. A polylactic acid resin containing a soft segment and having an organic carbon content ratio (% C _bio ) of biomass origin defined by the following Formula 1 being 60% by weight or more; And

With respect to the amount of monomer added for forming the polylactic acid repeating unit, a polylactic acid resin composition is provided that includes an antioxidant in an amount of 100 to 3000 ppmw:

[Formula 1]

(2)

[Formula 1]

% C = _Bio (poly ¹⁴ C isotope ratio by weight of the ¹² C isotope of carbon atoms of the lactic acid resin) / ⁽¹⁴ C isotope ratio by weight of the ^bio-12 C isotope of carbon atoms of the mass origin standard)

In the general formulas (1) and (2), A is a linear or branched alkylene group having 2 to 5 carbon atoms, m is an integer of 10 to 100, and n is an integer of 700 to 5000.

The polylactic acid resin composition includes a predetermined polylactic acid resin and a predetermined amount of an antioxidant, and the polylactic acid resin basically includes a polylactic acid repeating unit represented by Chemical Formula 1 as a hard segment. In addition, the polylactic acid resin includes a polyurethane polyol repeating unit as a soft segment, the polyurethane polyol repeating unit is a polyether polyol repeating unit represented by the formula (2) is a urethane bond (-C (= O) -NH- It has a structure that is linearly connected through).

Such polylactic acid resins basically exhibit biodegradability peculiar to biomass-based resins by including polylactic acid repeating units as hard segments. In addition, as a result of the experiments of the inventors, the polylactic acid resin has a greatly improved flexibility (for example, a relatively low Young's modulus when measured in the length and width directions) by including the polyurethane polyol repeating unit as a soft segment. It has been found to enable the provision of films exhibiting excellent transparency and low haze values as well as. Particularly, since such a soft segment is introduced into the poly (lactic acid) resin itself in combination with the hard segment, there is less concern that the soft segment for improving flexibility is bleed out or exhibits low stability, and the film containing the poly It was confirmed that the haze was increased or the transparency was lowered. Thus, it has been found that the polylactic acid resin enables the provision of films exhibiting excellent transparency and low haze values with improved flexibility. Moreover, the polylactic acid resin may exhibit the above-described effects without significantly increasing the content of the soft segment for improving flexibility.

In addition, the polylactic acid resin may exhibit biodegradability and environmentally friendly characteristics unique to the biomass-based resin as the polylactic acid repeating unit is included as a hard segment. Moreover, as described above, it is not necessary to greatly increase the content of the soft segment in order to improve flexibility, and may include a hard segment derived from a relatively high content of biomass-based resin such as polylactic acid resin. .

Accordingly, the polylactic acid resin included in the resin composition of the embodiment has an organic carbon content (% C _bio ) of biomass origin defined by Equation 1 of about 60% by weight or more, or about 70% by weight or more, or About 80% by weight, or about 85% by weight, or about 90% by weight, or about 95% by weight or more.

The measuring method of the organic carbon content rate (% C _bio ) of a biomass origin by the said Formula 1 can be based on the method as described in an ASTM D6866 standard, for example. The technical meaning and measurement method of such an organic carbon content (% C _bio ) are as follows.

In general, unlike organic materials such as resins derived from fossil raw materials, organic materials such as resins derived from biomass (biological resources) are known to contain isotopes ^14C . More specifically, all organic materials taken from living organisms, such as animals or plants, are ¹² C (about 98.892 wt%), ¹³ C (about 1.108 wt%) and ¹⁴ C (about 1.2 × 10 ^-10 wt%) as carbon atoms It is known to contain three isotopes, and the ratio of each isotope is known to remain constant. This is equal to the ratio of each isotope in the atmosphere, and this isotope ratio remains constant because living organisms continue to exchange carbon atoms with the external environment as they continue their metabolism.

On the other hand, ¹⁴ C is a radioisotope, and its content may decrease with time (t) according to Equation 2 below.

[Formula 2]

n = noexp (-at)

no represents the initial number of atoms of the ¹⁴ C isotope, n represents the number of atoms of the ¹⁴ C isotope remaining after t hours, and a represents the decay constant (or radioactive constant) associated with the half-life.

In Equation 2, the half-life of the ¹⁴ C isotope is about 5730 years. Given this half-life, organic materials taken from living organisms that constantly interact with the external environment, i.e. organic materials such as resins derived from biomass (biomass), are substantially constant despite the slight decrease in the isotope content. ^It is possible to maintain a constant content ratio (weight ratio) of ¹⁴ C isotope content and a constant content ratio with other isotopes, for example, ¹⁴ C / ¹² C = about 1.2 × 10 ⁻¹² .

In comparison, fossil fuels such as coal or petroleum have been blocked from exchanging carbon atoms with the outside environment for more than 50,000 years. Accordingly, the organic material such as the resin derived from the fossil raw material contains ¹⁴ C isotope at 0.2% or less of the initial content (atomic number) when estimated according to Equation 2, and does not substantially contain ¹⁴ C isotope. Do not.

Equation 1 considering the above-described points, the denominator may be a weight ratio of the isotope ¹⁴ C / ¹² C derived from the biomass, for example, about 1.2 × 10 ^-12 , the molecule is included in the resin to be measured Can be weight ratio of ¹⁴ C / ¹² C. As mentioned above, carbon atoms derived from biomass maintain an isotope weight ratio of about 1.2 × 10 ⁻¹² , whereas carbon atoms derived from fossil fuel have a substantially zero ratio of these isotope weight ratios. In the polylactic acid resin included in the resin composition of the embodiment, the organic carbon content rate (% C _bio ) of biomass origin among all carbon atoms may be measured by the above Equation 1. In this case, the content of each carbon isotope and the content ratio (weight ratio) thereof are described in the ASTM D6866-06 standard (a standard test method for determining the biobased content of natural substances using radiocarbon and isotope ratio mass spectrometry analysis). It can be measured according to one of three methods. Suitably, the carbon atoms contained in the resin to be measured may be in the form of graphite or carbon dioxide gas and measured by mass spectrometry or by liquid scintillation spectroscopy. In this case, two isotopes may be separated together with an accelerator for separating ¹⁴ C ions from ¹² C ions together with the mass spectrometer and the content and content ratio of each isotope may be measured by a mass spectrometer. Alternatively, the content and content ratio of each isotope may be determined by using liquid scintillation spectroscopy that is apparent to those skilled in the art, and thus the measurement value of Equation 1 may be derived.

As the measured value of the organic carbon content (% C _bio ) of Formula 1 thus obtained is about 60% by weight or more, the polylactic acid resin and the resin composition of one embodiment including the same are derived from biomass in a higher content. And carbon, and the polylactic acid resin and the resin composition of one embodiment may properly exhibit unique environmentally friendly properties and biodegradability.

More specifically, the polylactic acid resin that satisfies such a high organic carbon content (% C _bio ) and the resin composition of one embodiment including the same may exhibit environmentally friendly properties described below.

Biochemical products such as polylactic acid resins are biodegradable, with low carbon dioxide emissions, up to 108% less carbon dioxide emissions than current petrochemical products, and up to 50% energy savings for resin production. can do. In addition, the production of bioplastics using biomass materials is expected to reduce carbon dioxide emissions calculated by ISO 14000 compliant Life Cycle Analysis (LCA) by up to 70% compared to fossil materials.

As a specific example, according to NatureWorks, the production of PET resin produces 3.4 kg of carbon dioxide per kg, while polylactic acid resin, a kind of bioplastic, generates only 0.77 kg of carbon dioxide per kg, resulting in a reduction of about 77%. It is known that energy consumption is only 56% of PET. However, in the case of the polylactic acid resin previously known, there was a limitation in application due to low flexibility, and when including other components such as a plasticizer to solve this problem, there was a problem in that the advantages as the bioplastic mentioned above were greatly reduced.

However, the polylactic acid resin and the resin composition of one embodiment including the same satisfy the above-described high organic carbon content (% C _bio ), while fully utilizing the advantages as bioplastics, but also having problems such as low flexibility of the polylactic acid resin. It can be applied to various fields.

Accordingly, the polylactic acid resin and the resin composition of the embodiment including the same satisfying the high organic carbon content (% C _bio ) described above may exhibit environmentally friendly characteristics that greatly reduce carbon dioxide generation and energy usage by taking advantage of the bioplastics. Such environmentally friendly characteristics can be measured, for example, through Life Cycle Assessment of the resin composition of one embodiment.

On the other hand, the polylactic acid resin composition of one embodiment includes a specific content of antioxidant together with the polylactic acid resin described above. The present inventors have found that due to the inclusion of such an antioxidant, it is possible to suppress the yellowing of the polylactic acid resin and to provide a resin composition and a film having a good appearance, and completed the present invention. To this end, the resin composition of the embodiment has a content of about 100 to 3000 ppmw, or about 100 to 2000 ppmw, relative to the amount of monomer (eg, lactic acid or lactide) added for forming a polylactic acid repeating unit of the polylactic acid resin. Or an antioxidant in an amount of about 500 to 1500 ppmw, or about 1000 to 1500 ppmw. If the content of the antioxidant is too low, the polylactic acid resin may be yellowed by oxidation of the softening component such as the soft segment, and the appearance of the resin composition and the film may be poor. In addition, when the content of the antioxidant is excessively high, such an antioxidant may lower the polymerization rate of lactide, such that hard segments containing the polylactic acid repeating unit may not be properly produced, and the mechanical properties of the polylactic acid resin may be reduced. This can be degraded.

On the contrary, when using the resin composition of an embodiment including the antioxidant in an optimized content, for example, the polylactic acid resin and When obtaining the resin composition of one embodiment, it is possible to increase the productivity by improving the conversion (conversion of polymerization) and degree of polymerization (Degree of Polymerization) of the polylactic acid resin. In addition, in the film forming process requiring heating of 180 ° C. or higher with respect to the resin composition, since the resin composition can exhibit excellent thermal stability, it is possible to suppress the formation of monomers such as lactide or lactic acid or low molecular weight substances in the cyclic oligomer chain state. Can be. Accordingly, the molecular weight decrease of the polylactic acid resin or the color change (yellowing) of the film are suppressed, and not only have excellent appearance, but also show greatly improved flexibility, and excellent physical properties such as mechanical properties, heat resistance, and blocking resistance. The packaging film to be expressed can be provided.

As a result, the polylactic acid resin composition of the above-described embodiment can exhibit excellent biodegradability and eco-friendly characteristics peculiar to polylactic acid resin while exhibiting excellent flexibility and the like with a minimum content of the soft segment, and a film having excellent appearance and general properties. Enable the provision of. In particular, the resin composition of one embodiment and the polylactic acid resin contained therein solve the problem of low flexibility through the introduction of soft segments, while containing a resin component of biomass origin in a higher content to improve the environmentally friendly characteristics of the polylactic acid resin It becomes what can be displayed. In addition, the polylactic acid resin composition of the embodiment exhibits excellent physical properties such as excellent mechanical properties, stability, and transparency, and yellowing is suppressed, thereby providing a packaging film or the like having a good appearance.

Hereinafter, the polylactic acid resin composition of one embodiment will be described in more detail. First, the polylactic acid resin as a main component will be described in detail, and then the resin composition and film including the same will be described in detail.

In the polylactic acid resin composition of the above-described embodiment, the polylactic acid resin has a content of ¹⁴ C isotopes in carbon atoms of about 7.2 × 10 ⁻¹¹ wt% to 1.2 × 10 ⁻¹⁰ wt%, or about 9.6 × 10 ⁻¹¹ Weight percent to 1.2 × 10 ⁻¹⁰ weight percent, or about 1.08 × 10 ⁻¹⁰ weight percent to 1.2 × 10 ⁻¹⁰ weight percent. Polylactic acid resins having such ¹⁴ C isotope content may have more resin and carbon, or substantially all of the resin and carbon derived from the biomass, and may exhibit better biodegradability and environmentally friendly properties.

To this end, the polylactic acid resin may not only be derived from the biomass of the polylactic acid repeat unit of the hard segment, but may also be derived from the biomass polyether polyol repeat unit of the soft segment. Such polyether polyol repeating units can be obtained, for example, from polyether polyol resins derived from biomass. Such biomass may be of any plant or animal resource, for example, a plant resource such as corn, sugar cane, or tapioca. The polylactic acid-based polyol repeating unit derived from biomass and the polylactic acid resin derived from biomass and the resin composition of one embodiment including the same have a higher organic carbon content (% C _bio ), for example, about 90% by weight or more. Or an organic carbon content (% C _bio ) of at least about 95% by weight.

In the polylactic acid resin, the hard segment derived from the biomass has an organic carbon content (% C _bio ) of biomass origin defined by Equation 1 above about 90 wt% or more, for example, about 95 to 100 The soft segment derived from the biomass may have an organic carbon content (% C _bio ) of biomass origin defined by Equation 1 above about 70% by weight, or about 75 to 95% by weight. Can be. In the soft segment, a urethane bond connecting each polyether polyol repeating unit may be derived from a diisocyanate compound derived from a fossil fuel.

The polylactic acid resin included in the resin composition of the above-described embodiment is based on the standard ASTM D6866, as the organic carbon content (% C _bio ) of biomass origin is higher than about 60% by weight, or about 80% by weight or more. To meet the criteria for obtaining JBPA's "Biomass Pla" certification. Thus, the polylactic acid resin can legitimately attach JORA's "Biomass-based" label.

Meanwhile, in the aforementioned polylactic acid resin, the polylactic acid repeating unit of Formula 1 included in the hard segment may refer to a polylactic acid homopolymer or a repeating unit forming the same. Such polylactic acid repeating units can be obtained according to methods for preparing polylactic acid homopolymers well known to those skilled in the art. For example, L-lactide or D-lactide, which is a cyclic 2 monomer from L-lactic acid or D-lactic acid, is obtained by a ring-opening polymerization, or directly dehydration-condensation polymerization of L-lactic acid or D-lactic acid. It is preferable to obtain a polylactic acid repeating unit having a higher degree of polymerization through the ring-opening polymerization method. The poly (lactic acid) repeating unit may be prepared by copolymerizing L-lactide and D-lactide at a certain ratio so as to exhibit noncrystallinity. In order to further improve the heat resistance of the film containing the polylactic acid resin, L-lactide, or D-lactide. More specifically, the polylactic acid repeating unit can be obtained by ring-opening polymerization using an L-lactide or D-lactide raw material having an optical purity of 98% or more. If the optical purity is less than the above range, the melting temperature (Tm) Can be lowered.

In addition, the polyurethane polyol repeating unit included in the soft segment of the polylactic acid resin has a structure in which the polyether polyol repeating units of Formula 2 are linearly connected through a urethane bond (-C (= O) -NH-). Has More specifically, the polyether polyol repeating units refer to a polymer obtained by ring-opening (co) polymerizing a monomer such as an alkylene oxide or a repeating unit forming the same, and may have a hydroxyl group at a terminal thereof. The terminal hydroxyl group may react with the diisocyanate compound to form the urethane bond (-C (= O) -NH-), and the polyether polyol repeating units are linearly connected to each other through the urethane bond to the Polyurethane polyol repeating units can be achieved. By including such a polyurethane polyol repeating unit in a soft segment, the flexibility of the film containing the polylactic acid resin can be greatly improved. In addition, the polyurethane polyol repeating unit enables the provision of a film exhibiting excellent physical properties without deteriorating heat resistance, blocking resistance, mechanical properties or transparency of the polylactic acid resin composition or a film including the same.

On the other hand, polylactic acid-based copolymer or a resin composition or film containing the same has been known that includes a soft segment in which a polyester polyol repeating unit is connected by a urethane bond. However, such polylactic acid copolymers have problems such as low transparency of the polyester polyol and polylactic acid, resulting in decreased transparency of the film and higher haze value. In addition, the polylactic acid-based copolymer has a wide molecular weight distribution and poor melting characteristics, so that the film extrusion state is not good, and the mechanical properties, heat resistance, and blocking resistance of the film are also insufficient.

In addition, a polylactic acid copolymer having a polyether polyol repeating unit copolymerized with a polylactic acid repeating unit and a branched form using a trifunctional or higher isocyanate compound, or after copolymerizing the polyether polyol repeating unit and the polylactic acid repeating unit, Polylactic acid copolymers in the form of chain extension by urethane reactions have also been previously known. However, these previously known polylactic acid copolymers also have a small block size of the polylactic acid repeating unit corresponding to the hard segment, which is not sufficient for heat resistance, mechanical properties and blocking resistance of the film, and has a wide molecular weight distribution and melting characteristics. This defect still had problems such as poor film extrusion.

In contrast, a polylactic acid resin comprising a polyurethane polyol repeating unit and a polylactic acid repeating unit linearly connected to a plurality of polyether polyol repeating units via a urethane bond, and a resin composition of one embodiment including the same, the polyurethane polyol repeating While allowing the provision of a film showing excellent flexibility by unit, it can exhibit a high molecular weight and a narrow molecular weight distribution and include polylactic acid repeating units in a large segment size, so that the film can exhibit excellent mechanical properties, heat resistance and blocking resistance, etc. To be. Accordingly, it has been found that the polylactic acid resin and the resin composition of one embodiment including the same solve all of the problems of the copolymers known in the art, thereby providing a film having excellent flexibility and greatly improving flexibility.

The polyether polyol repeating unit and the diisocyanate compound react with each other such that the molar ratio of the terminal hydroxyl group of the polyether polyol repeating unit: the isocyanate group of the compound of the diisocyanate compound is about 1: 0.50 to about 1: 0.99. Urethane polyol repeating units may be formed. Preferably, the reaction molar ratio of the terminal hydroxyl group: isocyanate group of the diisocyanate compound of the polyether polyol repeating units is about 1: 0.60 to about 1: 0.95, more preferably about 1: 0.70 to about 1: 0.90. Can be.

As will be described in more detail below, the polyurethane polyol repeating unit refers to a polymer formed by linearly connecting the polyether-based polyol repeating units via a urethane bond or a repeating unit forming the same, and may have a hydroxyl group at a terminal thereof. have. Accordingly, the polyurethane polyol repeating unit may act as an initiator in the polymerization process for forming the polylactic acid repeating unit. However, when the reaction molar ratio of the hydroxy group: isocyanate group is excessively higher than 0.99, the number of terminal hydroxyl groups of the polyurethane polyol repeating unit is insufficient (OHV <2), and thus may not function properly as an initiator. Moreover, when the reaction molar ratio of the said hydroxyl group: isocyanate group becomes low too much, the number of terminal hydroxyl groups of the said polyurethane polyol repeating unit will become too large (OHV> 21), and it will become difficult to obtain a high molecular weight polylactic acid repeating unit and a polylactic acid resin.

On the other hand, the polyether polyol repeating unit may be, for example, a polyether polyol (co) polymer obtained by ring-opening (co) polymerizing one or more alkylene oxides or a repeating unit thereof. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide or tetrahydrofuran, and examples of the polyether polyol repeating unit obtained therefrom include repeating units of polyethylene glycol (PEG); Repeating units of poly (1,2-propylene glycol); Repeating units of poly (1,3-propanediol); Repeating units of polytetramethylene glycol; Repeating units of polybutylene glycol; A repeating unit of a polyol which is a copolymer of propylene oxide and tetrahydrofuran; A repeating unit of a polyol which is a copolymer of ethylene oxide and tetrahydrofuran; Or a repeating unit of a polyol which is a copolymer of ethylene oxide and propylene oxide. Considering flexibility imparted to the poly (lactic acid) resin film, affinity with the poly (lactic acid) repeating unit and humidifying property, the polyether polyol repeating unit may be a repeating unit of poly (1,3-propanediol) or polytetramethylene glycol Is preferably used.

In addition, such polyether polyol repeating units may have a number average molecular weight of about 450 to 9000, preferably about 1000 to 3000. If the molecular weight of such a polyether polyol repeating unit is too large or small, the flexibility or mechanical properties of the film obtained from the polylactic acid resin and the resin composition of one embodiment may not be sufficient. In addition, since the polylactic acid resin may be difficult to satisfy appropriate molecular weight characteristics, the processability of the resin composition may be lowered, or the flexibility or mechanical properties of the film may be lowered.

The diisocyanate compound capable of bonding with the terminal hydroxyl group of the polyether polyol repeating unit to form a urethane bond can be any compound having two isocyanate groups in the molecule. Examples of such diisocyanate compounds include 1,6-hexamethylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, 1 , 5-naphthalene diisocyanate, m-phenylenedi isocyanate, p-phenylenedi isocyanate, 3,3'-dimethyl-4,4'- diphenylmethane diisocyanate, 4,4'-bisphenylenedi isocyanate, hexamethylene di Isocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, etc. are mentioned, In addition, various diisocyanate compounds well known to those skilled in the art can be used without a restriction | limiting. However, it is preferable to use 1,6-hexamethylene diisocyanate in view of imparting flexibility to the poly (lactic acid) resin film.

Meanwhile, the polylactic acid resin included in the resin composition of one embodiment may include a block copolymer in which the polylactic acid repeating unit of the hard segment described above is combined with the polyurethane polyol repeating unit of the soft segment. More specifically, in such a block copolymer, the terminal carboxyl group of the polylactic acid repeating unit may form an ester bond with the terminal hydroxy group of the polyurethane polyol repeating unit. For example, the chemical structure of such a block copolymer can be represented by the following general formula 1:

[Formula 1]

Polylactic Acid Repeating Unit (L) -Ester-Polyurethane Polyol Repeating Unit (E-U-E-U-E) -Ester-Polylactic Acid Repeating Unit (L)

In Formula 1, E represents a polyether polyol repeating unit, U represents a urethane bond, and Ester represents an ester bond.

By including a block copolymer in which the polylactic acid repeating unit and the polyurethane polyol repeating unit are combined, the polyurethane polyol repeating unit for providing flexibility may be prevented from bleeding out of the film formed of the resin composition. Various physical properties such as transparency, mechanical properties, heat resistance or blocking resistance may be excellent. In addition, as at least a portion of the polylactic acid repeating unit and the polyurethane polyol repeating unit take the form of a block copolymer, the molecular weight distribution, glass transition temperature (Tg), melting temperature (Tm), etc. of the polylactic acid resin are optimized. The mechanical properties, flexibility and heat resistance of the film can be further improved.

However, all of the polylactic acid repeating units included in the polylactic acid resin and the resin composition need not be in the form of a block copolymer combined with the polyurethane polyol repeating unit, and at least some of the polylactic acid repeating units may be It may also take the form of a polylactic acid homopolymer without being bound to the urethane polyol repeating unit. In this case, the polylactic acid resin may be in the form of a mixture including the above-described block copolymer and a polylactic acid repeating unit that is not bonded to the polyurethane polyol repeating unit, that is, a polylactic acid homopolymer.

On the other hand, the polylactic acid resin is based on 100 parts by weight of its total (100 parts by weight of the block copolymer described above, and optionally, if the polylactic acid homopolymer is included, 100 parts by weight of the sum of the homopolymer), as described above About 65 to 95 parts by weight, or about 80 to 95 parts by weight, or about 82 to 92 parts by weight of the hard segment, and about 5 to 35 parts by weight, or about 5 to 20 parts by weight, or about 8 to 18 parts by weight of the soft segment It may include parts by weight.

When the content of the soft segment is excessively high, it may be difficult to provide a high molecular weight polylactic acid resin and a resin composition including the same, which may lower mechanical properties such as strength of the film. In addition, the glass transition temperature is lowered, so that slipping, handleability or shape retention characteristics may be deteriorated during packaging using a film. On the contrary, if the content of the soft segment is too low, there is a limit in improving the flexibility of the polylactic acid resin and the film. In particular, the glass transition temperature of the polylactic acid resin may be excessively high, and thus the flexibility of the film may be reduced, and the polyurethane polyol repeating unit of the soft segment is difficult to function properly as an initiator, resulting in poor polymerization conversion or high molecular weight polylactic acid resin. It may not be manufactured.

The polylactic acid resin composition of the above-described embodiment includes an antioxidant in a specific content together with the polylactic acid resin described above. As described above, such an antioxidant may be included in a specific content to suppress yellowing of the polylactic acid resin to improve the appearance of the resin composition and the film. Moreover, the said antioxidant can suppress that a soft segment etc. are oxidized or thermally decomposed.

As such antioxidants, one or more kinds of Hindered phenol antioxidants, amine antioxidants, thio antioxidants or phosphite antioxidants may be used, and various antioxidants known to be usable in other polylactic acid resin compositions may be used. Can be.

 However, since the resin composition of the embodiment has polyether polyol repeating units, it tends to be easily oxidized or thermally decomposed during high temperature polymerization or molding at high temperature polymerization. Therefore, it is preferable to use the above-mentioned series of heat stabilizers, polymerization stabilizers or antioxidants as the antioxidant. Specific examples of such antioxidants include phosphoric acid type heat stabilizers such as phosphoric acid, trimethyl phosphate or triethyl phosphate; 2,6-di-t-butyl-p-cresol, octadecyl-3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, tetrabis [methylene-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy Benzyl) benzene, 3,5-di-t-butyl-4-hydroxybenzylphosphite diethyl ester, 4,4'-butylidene-bis (3-methyl-6-t-butylphenol), 4, Hindered phenols such as 4'-thiobis (3-methyl-6-t-butylphenol) or Bis [3,3-bis- (4'-hydroxy-3'-tert-butyl-phenyl) butanoicacid] glycol ester Primary antioxidants; Amines such as phenyl-α-naphthylamine, phenyl-β-naphthylamine, N, N'-diphenyl-p-phenylenediamine or N, N'-di-β-naphthyl-p-phenylenediamine System secondary antioxidants; Thio such as dilauryl disulfide, dilauryl thiopropionate, distearyl thiopropionate, mercaptobenzothiazole, or tetramethyl thiuram disulfide tetrabis [methylene-3- (laurylthio) propionate] Secondary antioxidants are; Or triphenyl phosphite, tris (nonylphenyl) phosphite, triisodecylphosphite, Bis (2,4-di-tbutylphenyl) Pentaerythritol Diphosphite or (1,1'-Biphenyl) -4,4'-Diylbisphosphonous acid tetrakis Phosphite secondary antioxidants such as [2,4-bis (1,1-dimethylethyl) phenyl] ester. Among them, it is most preferable to use a combination of a phosphite-based antioxidant and another antioxidant.

As already mentioned above, the antioxidant is about 100 to 3000 ppmw, or about 100 to 2000 ppmw, or about 500 to 1500 ppmw, or about 1000 based on the amount of monomer added for forming the polylactic acid repeating unit in the resin composition. It may be included in the content of 1500ppmw. When the content of the antioxidant is too low, the polylactic acid resin may be yellowed by oxidation or the like in the softening component such as the soft segment, and the appearance of the resin composition and the film may be poor. In addition, when the content of the antioxidant is excessively high, such an antioxidant may lower the polymerization rate of lactide, such that hard segments containing the polylactic acid repeating unit may not be properly produced, and the mechanical properties of the polylactic acid resin may be reduced. This can be degraded.

In addition to the above-mentioned antioxidants, the polylactic acid resins may be used in various known plasticizers, UV stabilizers, colorants, mattes, deodorants, flame retardants, weathering agents, antistatic agents, mold release agents, antioxidants, and ion exchanges within a range that does not impair the effect thereof. Various additives, such as a coloring pigment, an inorganic or organic particle, may also be further included.

Examples of the plasticizer include phthalic ester plasticizers such as diethyl phthalate, dioctyl phthalate and dicyclohexyl phthalate; Aliphatic dibasic acid ester plasticizers such as di-1-butyl adipic acid, di-n-octyl adipic acid, di-n-butyl sebacic acid, and di-2-ethyl hexyl azaline acid; Phosphoric ester plasticizers such as diphenyl-2-ethylhexyl phosphate and diphenyl octyl phosphate; Hydroxy polyhydric carboxylic acid ester plasticizers such as acetyl citric acid tributyl, acetyl citric acid tri-2-ethyl hexyl and tributyl citric acid; Fatty acid ester plasticizers such as acetyl ricinolic acid methyl and stearic acid diyl; Polyhydric alcohol ester plasticizers such as glycerin tri acetate; Epoxy plasticizers, such as epoxidized soybean oil, epoxidized amani oil fatty acid butyl ester, and octyl epoxy stearate, etc. are mentioned. Moreover, as an example of a coloring pigment, inorganic pigments, such as carbon black, titanium oxide, zinc oxide, iron oxide; Organic pigments such as cyanine-based, phosphorus-based, quinone-based, lerione-based, isoindolinone-based and thio-indigo-based; In order to improve the blocking resistance of other films, inorganic or organic particles may be further included. Examples include silica, colloidal silica, alumina, alumina sol, talc, mica, calcium carbonate, polystyrene, polymethyl methacrylate, and silicone. Etc. can be mentioned. In addition, various additives known to be usable in the polylactic acid resin or the film thereof can be included, and the specific kind and the method of obtaining it are known to those skilled in the art.

The polylactic acid resin in the resin composition described above, for example, the block copolymer contained therein, may have a number average molecular weight of about 50,000 to 200,000, preferably a number average molecular weight of about 50,000 to 150,000. In addition, the polylactic acid resin may have a weight average molecular weight of about 100,000 to 400,000, preferably a weight average molecular weight of about 100,000 to 320,000. Such a molecular weight may affect the workability of the resin composition and the mechanical properties of the film. When the molecular weight is too small, the melt viscosity may be excessively low when melt-processed by a method such as extrusion, which may result in deterioration of workability in a film or the like, and mechanical properties such as strength may be deteriorated even if processing into a film is possible. On the other hand, when the molecular weight is too large, the melt viscosity during melt processing is excessively high, and productivity and workability as a film may be greatly reduced.

In addition, the polylactic acid resin, for example, the block copolymer contained therein has a molecular weight distribution (Mw / Mn) defined as a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of about 1.60 to 2.20, preferably Preferably about 1.80 to 2.15. As the polylactic acid resin exhibits such a narrow molecular weight distribution, it exhibits proper melt viscosity and melt characteristics when melt processing by extrusion or the like, and thus exhibits excellent film extrusion state and processability. In addition, the film containing the polylactic acid resin may exhibit excellent mechanical properties such as strength. In contrast, when the molecular weight distribution becomes too narrow (small), the melt viscosity is too large at the processing temperature for extrusion or the like, so that processing as a film may be difficult, and conversely, when the molecular weight distribution becomes too wide (large), the strength of the film The mechanical properties such as lowering or the melt viscosity is too small, such as poor melt characteristics may make the molding itself difficult to film or the film extrusion may not be good.

In addition, the polylactic acid resin may have a melting temperature (Tm) of about 155 to 178 ° C, or about 160 to 178 ° C, or about 165 to 175 ° C. If the melting temperature is too low, the heat resistance of the film containing the poly (lactic acid) resin may be deteriorated. If it is too high, a high temperature is required in the melt processing by extrusion or the like, or the viscosity becomes too high, .

The polylactic acid resin, for example, the block copolymer contained therein, has a glass transition temperature (Tg) of about 8 to 55 ° C, or about 25 to 55 ° C, or about 30 to 55 ° C. As these polylactic acid resins exhibit such a glass transition temperature range, the flexibility or stiffness of the film containing the resin composition of one embodiment of the invention is properly maintained and can be preferably used as a packaging film. If the glass transition temperature of the polylactic acid resin is too low, the flexibility of the film may be improved, but as the stiffness is too low, the slipping, handling, shape retention characteristics or resistance to the packaging process using the film may be improved. The blocking property or the like may be poor, and therefore, application to a packaging film may be inadequate. On the contrary, when the glass transition temperature is too high, the film may have low flexibility and too high stiffness, so that the film may not be easily folded and its marks may be lost or the adhesion to the target product in packaging may be poor. Further, noise may be generated severely during packaging of the film, which may limit its application to packaging films.

On the other hand, the resin composition according to an embodiment of the above-described invention is less than about 1% by weight of the monomer (eg, polylactic acid repeating unit used for the production of the polylactic acid repeating unit, based on the weight of the polylactic acid resin contained therein Monomers, etc.), and more preferably only about 0.01 to 0.5% by weight of monomers may remain. The resin composition includes a block copolymer having specific structural properties, a polylactic acid resin including the same, and a specific content of an antioxidant, so that most of the lactide monomers used during the manufacturing process participate in the polymerization to repeat the polylactic acid repeating unit. And depolymerization or decomposition of the polylactic acid resin also does not substantially occur. For this reason, the polylactic acid resin composition of the above embodiment may include a residual monomer having a minimized content, for example, a residual lactide monomer.

If the residual monomer content is about 1% by weight or more, a odor problem occurs when processing the film using the resin composition, and also a decrease in the molecular weight of the polylactic acid resin due to the film processing causes a decrease in the strength of the final film, in particular, Even in food packaging applications, residual monomers may be bleed-out and cause stability problems.

On the other hand, the polylactic acid resin composition may have a color-b value of less than 6 in a chip state, preferably 5 or less. The resin composition of one embodiment may include an optimized amount of antioxidant, so that yellowing of the polylactic acid resin may be suppressed, thereby exhibiting a color-b value of less than 6. If the color-b value of the resin composition is 6 or more, the appearance of the film may be poor when the film is developed for use, and thus the product value may be degraded.

On the other hand, the above-mentioned polylactic acid resin composition and the polylactic acid resin contained therein are steps of ring-opening (co) polymerizing one or more monomers such as alkylene oxide to form a (co) polymer having a polyether polyol repeating unit; Reacting the (co) polymer with a diisocyanate compound in the presence of a urethane reaction catalyst to form a (co) polymer having a polyurethane polyol repeating unit; And polycondensing the lactic acid (D or L-lactic acid) or ring-opening polymerizing the lactide (D or L-lactide) in the presence of the (co) polymer having the antioxidant and polyurethane polyol repeating units. It can be manufactured by a manufacturing method. In this case, the lactic acid or lactide and the polylactic acid repeat unit formed therefrom may be of biomass, and suitably the alkylene oxide and the polyether polyol repeat unit formed therefrom may also be of biomass. have.

According to this manufacturing method, the polylactic acid repeating unit of Formula 1 is included as a hard segment, and together, a polylactic acid resin including a predetermined polyurethane polyol repeating unit as a soft segment may be prepared. In addition, as the antioxidant is used in the generation of the polylactic acid repeating unit, the polylactic acid resin composition of one embodiment including the polylactic acid resin and the antioxidant may be prepared.

More specifically, in the production method, a polyether polyol (co) polymer having a repeating unit of Formula 2 causes a urethane reaction with a diisocyanate compound, so that many of the repeating units of Formula 2 are linearly connected through a urethane bond. (Co) polymers with polyurethane polyol repeating units can be formed. In addition, the hydroxy groups at the end of the polymer act as an initiator to condense the polylactic acid repeating unit and the polyurethane polyol repeating unit as the polylactic acid repeating unit is formed as a result of the polycondensation of the lactic acid or the ring-opening polymerization of the lactide. Polylactic acid resin including a soft segment may be prepared. Furthermore, when the polylactic acid repeating unit is formed by polymerizing the lactide, the resin composition of one embodiment including the polylactic acid resin and the antioxidant suppressed by yellowing is prepared together by using an antioxidant of a specific content together. Can be. Such a resin composition exhibits greatly improved flexibility by polyurethane polyol repeating units, but also exhibits excellent mechanical properties, heat resistance, blocking resistance, and the like, and yellowing is suppressed, thereby providing a favorable film.

In addition, the polylactic acid resin prepared by the above-described method has a hard segment and optionally a soft segment originating from biomass, and the organic carbon content rate (% C _bio ) of biomass origin defined by Equation 1 is about 60% by weight. It can be more than.

Compared with such a production method, in the case of introducing a polyester-based polyol repeating unit which is not a polyether-based polyol repeating unit, or polymerizing the polyether-based polyol first with lactic acid or the like in a different reaction order, and then extending the chain, Block copolymers having excellent properties and polylactic acid resins including the same are difficult to prepare. In addition, in this case, in order to achieve excellent flexibility, it is necessary to introduce another resin such as a polyester-based polyol repeating unit of a higher content of fossil fuel, and thus the organic carbon content of about 60% by weight (% C _bio ) Can be difficult to achieve.

In addition, appropriately controlling the amount of the (co) polymer having a polyurethane polyol repeating unit corresponding to the molecular weight of the overall polylactic acid resin, the molecular weight of the polyether polyol (co) polymer, or the content of the soft segment is also described above. It is a major factor that enables polylactic acid resins having excellent physical properties to be produced. However, since a suitable range such as the molecular weight of the polylactic acid resin or the content of the soft segment has already been described above, further detailed description thereof will be omitted.

Hereinafter, the manufacturing method of such a polylactic acid resin composition will be explained in more detail.

First, at least one monomer such as alkylene oxide is ring-opened (co) polymerized to form a (co) polymer having a polyether polyol repeating unit, which is a method for preparing a polyether-based polyol (co) polymer. You can proceed accordingly.

Thereafter, the (co) polymer having the polyether polyol repeating unit, the diisocyanate compound and the urethane reaction catalyst are charged in the reactor, heated and stirred to perform the urethane reaction. By this reaction, two isocyanate groups of the diisocyanate compound and a terminal hydroxyl group of the (co) polymer are bonded to each other to form a urethane bond. As a result, a (co) polymer having a polyurethane polyol repeating unit in a form in which polyether polyol repeating units are linearly linked through the urethane bond can be formed, which is included as the soft segment of the polylactic acid resin described above. In this case, the polyurethane polyol (co) polymer is a polyether polyol repeating units (E) are linearly bonded in the form of EUEUE via a urethane bond (U) to form a form having a polyether polyol repeating unit at both ends Can be.

In this case, the alkylene oxide and the polyether polyol repeating units obtained therefrom may be derived from biomass such as plant resources, and thus, the polyurethane polyol (co) polymer may contain an organic carbon content rate (%) of biomass origin. C _bio ) may be about 70% by weight or more and become quite high.

The urethane reaction can be carried out in the presence of a conventional tin-based catalyst, for example, Stannous Octoate, Dibutyltin Dilaurate, Dioctyltin Dilaurate and the like. In addition, the urethane reaction may be carried out under reaction conditions for the production of conventional polyurethane resin. For example, after adding a diisocyanate compound and a polyether polyol (co) polymer in a nitrogen atmosphere, the urethane reaction catalyst is added and reacted at a reaction temperature of 70 to 80 ° C. for 1 to 5 hours to have a polyurethane polyol repeating unit. (Co) polymers can be prepared.

Subsequently, polycondensation of the lactic acid (D or L-lactic acid) or ring-opening polymerization of the lactide (D or L-lactide) in the presence of the (co) polymer having the polyurethane polyol repeating unit and a specific amount of antioxidant When the above-mentioned block copolymer (or polylactic acid resin including the same) and a predetermined amount of the polylactic acid resin composition including an antioxidant may be prepared. That is, when undergoing such a polymerization reaction, a polylactic acid repeating unit included as a hard segment is formed while yellowing due to oxidation of the soft segment is suppressed by an antioxidant, thereby producing the polylactic acid resin, wherein at least some poly The polyurethane polyol repeating unit may be bonded to the end of the lactic acid repeating unit to form a block copolymer.

As a result, a known polylactic acid copolymer of a form in which a prepolymer in which a polyether polyol and a polylactic acid are first bonded and then chain-extended these prepolymers with a diisocyanate compound, or the prepolymers are trifunctional or higher isocyanate compounds. A block copolymer showing a structure and properties different from a known branched copolymer reacted with a resin composition and a resin composition containing the same may be formed. In particular, since the block copolymer may include blocks (hard segments) in which polylactic acid repeating units are bonded to each other in relatively large units (molecular weight), the film formed of the polylactic acid resin including the same has a narrow molecular weight distribution and an appropriate Tg, Accordingly, excellent mechanical properties and heat resistance can be exhibited. In contrast, the above known copolymer has a structure in which polylactic acid repeating units of small units (molecular weight) are randomly arranged alternately with polyether polyol repeating units and the like, and thus the film obtained therefrom exhibits characteristics such as molecular weight distribution as described above. It is not satisfied and mechanical properties and heat resistance are not enough. Moreover, since the block copolymer may be prepared while the yellowing is suppressed by the antioxidant during the polymerization, the resin composition and the film including the same may also exhibit an excellent appearance state.

Meanwhile, the lactide ring-opening polymerization may be performed in the presence of a metal catalyst including an alkaline earth metal, a rare earth metal, a transition metal, aluminum, germanium, tin or antimony. More specifically, such metal catalysts may be in the form of carbonates, alkoxy degrees, halides, oxides or carbonates of these metals. Preferably, as the metal catalyst, tin octylic acid, titanium tetraisopropoxide, aluminum triisopropoxide, or the like can be used.

In addition, the step of forming a polylactic acid repeating unit such as the lactide ring-opening polymerization reaction described above may be continuously performed in the same reactor in which the urethane reaction is performed. That is, the polyether polyol polymer and the diisocyanate compound may be urethane reacted to form a polymer having a polyurethane polyol repeating unit, and then a monomer such as lactide and a catalyst may be continuously added to form a polylactic acid repeating unit. have. As a result, while the polymer having a polyurethane polyol repeating unit serves as an initiator, the polylactic acid repeating unit and the polylactic acid resin containing the same can be continuously produced in high yield and high productivity.

The above-mentioned poly (lactic acid) resin composition can exhibit improved flexibility while exhibiting biodegradability of the poly (lactic acid) resin, since it includes a block copolymer (poly (lactic acid resin)) having a specific hard segment and a soft segment bonded thereto. Also, the soft segment for imparting flexibility can be minimized to be bleed out, and the degradation of mechanical properties, heat resistance, transparency or haze characteristics of the film can be greatly reduced by the addition of such a soft segment.

In addition, since the polylactic acid resin is manufactured to have a predetermined glass transition temperature and optionally a predetermined melting temperature, the film or the like obtained therefrom may exhibit optimized flexibility and stiffness as a packaging material, as well as melt processability. It becomes excellent and the blocking resistance and heat resistance are further improved. Therefore, such a polylactic acid resin and the resin composition of one embodiment including the same can be very preferably applied to packaging materials such as films. In addition, the polylactic acid resin has a relatively high organic carbon content (% C _bio ) of biomass origin, which may exhibit excellent biodegradability and environmentally friendly characteristics, as described above.

In addition, the polylactic acid resin may be included with a specific amount of an antioxidant, and yellowing may be suppressed during manufacture or use, and the resin composition including these components may exhibit excellent appearance and merchandise, and have greatly improved flexibility and superiority. It is possible to provide a packaging film exhibiting various physical properties such as mechanical properties.

According to another embodiment of the present invention, there is provided a packaging film comprising the polylactic acid resin composition described above. As the packaging film includes the polylactic acid resin composition described above, it is not only excellent in mechanical properties, heat resistance, blocking resistance, transparency and processability, but also can exhibit optimized flexibility and stiffness, and has a good appearance without yellowing and Since it can exhibit environmentally friendly properties, it can be very preferably used as a packaging material in various fields.

Such a packaging film may have various thicknesses according to each use, and may have a thickness of about 5 to 500 μm. For example, when used as a packaging film such as a wrap film or an envelope, in terms of flexibility, handleability and strength, a thickness of about 5 to 100 µm, preferably about 7 to 50 µm, more preferably about 7 to It may have a thickness of 30 ㎛.

In addition, the packaging film was subjected to a tensile test on a specimen having a width of 10 mm and a length of 150 mm at a temperature of 20 ° C. and a relative humidity of 65% using an Instron 1123 UTM universal testing machine at a drawing speed of 300 mm / min and a distance of 100 mm between grips. In this case, the total Young's modulus in the longitudinal direction and the width direction may be about 350 to 750 kgf / mm 2, preferably about 450 to 650 kgf / mm 2, more preferably about 500 to 600 kgf / mm 2. . The range of this Young's modulus sum can reflect the optimized flexibility and stiffness of the packaging film, and this flexibility and stiffness seems to be due to the polylactic acid resin satisfying the above-described structural properties, glass transition temperature and the like.

However, when the total Young's modulus is too low, spreading or loosening may occur during film formation and processing of the film, and handling, process permeability, slit processability, or shape retention characteristics may be poor. In addition, when the wrap film is used, the releasability of the film may be insufficient due to insufficient slip of the film, and efficient packaging may be difficult due to deformation of the film before wrapping an article or food such as a container. On the contrary, when the Young's modulus is excessively high, folding lines remain unchanged when the film is folded at the time of pavement processing, and the pavement may not be easily deformed depending on the shape of the article or food to be packed.

When the packaging film is subjected to a tensile test under the same conditions as the Young's modulus, an initial tensile strength of about 10 kgf / mm 2 or more, preferably an initial tensile strength of about 12 kgf / mm 2 or more, more preferably in both its longitudinal direction and its width direction Preferably it may have an initial tensile strength of at least about 15 kgf / mm 2 and up to 30 kgf / mm 2. If the initial tensile strength is lower than this, the handling property of the film becomes poor, and even after packaging, the film may be easily broken and the contents may be damaged.

In addition, the packaging film may have a weight change rate of about 3 wt% or less, preferably about 0.01 to 3.0 wt%, and more preferably about 0.05 to 1.0 wt% when treated at 100 ° C. in a hot air oven for 1 hour. These properties may reflect the excellent heat resistance and anti-bleed out characteristics of the packaging film. If the weight change rate is about 3 wt% or more, the dimensional stability of the film becomes poor, which means that plasticizers, residual monomers, or additives bleed out, and these components may contaminate the package contents.

The packaging film may have a haze of about 3% or less, a transmittance of about 85% or more, preferably a haze of about 2% or less, a transmittance of about 90% or more, and more preferably a haze of It may be about 1% or less and the transmittance may be about 92% or more. If the haze is too large or the transmittance is too low, the contents can not easily be distinguished during packaging of the film, and the printed image is hard to appear clearly when the multilayer film using the printing layer is applied.

The above-mentioned packaging film may provide the properties required as a food packaging material such as heat sealing property, gas barrier property such as water vapor, oxygen or carbon dioxide, release property, printability, etc. in a range that does not impair the effect. . To this end, it is also possible to blend a compound of the polymer having such properties into a film, or to coat at least one surface of the packaging film with a thermoplastic resin such as an acrylic resin, a polyester resin, a silicone resin, an antistatic agent, a surfactant, have. As another method, another film having a function such as a polyolefin-based sealant or the like may be co-extruded to form a multilayer film. Or may be produced in the form of a multilayer film by other methods such as adhesion or lamination.

On the other hand, the packaging film described above can be produced by a conventional method. For example, the polylactic acid resin may be formed in the form of a stretched film by applying an inflation method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, or the like, and then heat-fix it. At this time, the stretched film forming process is melt-extruded the polylactic acid resin on a sheet by an extruder equipped with a T die, and cooled and solidified the sheet-like molten extrudate to obtain an unstretched film, and then length the unstretched film It can advance by the method of extending | stretching to a direction and a width direction.

The stretching conditions of the film can be suitably adjusted according to heat shrinkage characteristics, dimensional stability, strength, Young's modulus and the like. For example, in view of the strength and flexibility of the final packaging film, it is preferable that the stretching temperature is adjusted to be above the glass transition temperature and below the crystallization temperature of the polylactic acid resin. In addition, the stretching ratio may be in the range of about 1.5 to 10 times in the length and width directions, respectively, and the length and width direction stretching ratios may be adjusted differently.

After the stretched film is formed by such a method, the film for wrapping is finally manufactured through heat fixation. It is preferable that such heat fixation is performed for at least 10 seconds at 100 ° C or more for the strength and dimensional stability of the film.

The packaging film described above can exhibit mechanical properties such as sufficient strength and anti-bleed out characteristics as well as excellent flexibility and transparency even when stored for a long period of time. In addition, it can exhibit the eco-friendly properties and biodegradability peculiar to polylactic acid resin. Therefore, such packaging films can be suitably applied as packaging materials in various fields. For example, consumer or grocery general packaging / envelopes, refrigerated / frozen food packaging, shrinkable over-wrapping films, bundle bundle films, sanitary napkins such as sanitary napkins or baby products, lamination films, shrinkable label packaging and snack film mat films In addition, it can be widely used as a packaging material for industrial materials, such as agricultural multi-film, automotive film protection sheet, garbage bags and compost bags.

As described above, according to the present invention, a polylactic acid resin exhibiting environmentally friendly characteristics and biodegradability peculiar to a polylactic acid resin, but also having optimized flexibility and stiffness, excellent mechanical properties, heat resistance, transparency, blocking resistance and film processability, etc. And a packaging film can be provided. Therefore, such a polylactic acid resin and a packaging film can be preferably applied as a packaging material in various fields to replace the packaging film obtained from a crude oil-based resin, and can greatly contribute to preventing environmental pollution.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

* Definition of physical properties and measuring method: The definitions and measuring methods of the respective physical properties in the examples described below are summarized below.

(1) NCO / OH: terminal hydroxyl groups of isocyanate groups / polyether-based polyol repeating units (or (co) polymers) of diisocyanate compounds (e.g., hexamethylene diisocyanate) for the formation of polyurethane polyol repeating units Represents the reaction molar ratio of ".

(2) OHV (KOHmg / g): The polyurethane polyol repeating unit (or (co) polymer) was dissolved in dichloromethane and then acetylated, and the acetic acid produced by hydrolysis was measured by titrating with 0.1 N KOH methanol solution. . This corresponds to the number of hydroxyl groups present at the end of the polyurethane polyol repeat unit (or (co) polymer).

(3) Mw and Mn (g / mol), molecular weight distribution (Mw / Mn): polylactic acid resin was dissolved in Chloroform at a concentration of 0.25% by weight, and gel permeation chromatography (Viscotek TDA 305, Column: Shodex LF804 * 2ea) was used, and polystyrene was used as the standard to calculate the weight average molecular weight (Mw) and the number average molecular weight (Mn), respectively. The molecular weight distribution value was calculated from Mw and Mn thus calculated.

(4) Tg (glass transition temperature, 占 폚): Measured by heating the sample at 10 占 폚 / min after melting and quenching the sample using a differential scanning calorimeter (TA Instruments). The midline of the baseline and each tangent line near the endothermic curve was Tg.

(5) Tm (melting temperature, ° C): After using a differential scanning calorimeter (TA Instruments), the sample was melted and quenched and then measured at a temperature of 10 ° C / min. The maximum value temperature of the melting endothermic peak of the crystal was Tm.

(8) Residual monomer (lactide) content (% by weight): After dissolving 0.1 g of resin in 4 ml of Chloroform, 10 ml of Hexane was filtered and quantified by GC analysis.

(7) Content of Polyurethane Polyol Repeating Unit (wt%): The content of the polyurethane polyol repeating unit included in each prepared polylactic acid resin was quantified using a 600 Mhz nuclear magnetic resonance (NMR) spectrometer.

(8) chip color-b: Resin Chip was represented by the average value of five tests in total using a Chroma meter CR-410 manufactured by Konica Minolta Sensing.

(9) Extrusion State and Melt Viscosity: Extruded polylactic acid resin into sheet on 200 ~ 250 ℃ extrusion temperature and cooled to 5 ℃ in 30mm single screw extruder equipped with T die for making unstretched sheet. The blackout was cast on one drum. At this time, the melt viscosity of the discharge on the sheet was measured using a Physica Rheometer of Physica, USA. Specifically, the melt viscosity of the molten resin at shear rate (1 / s) = 1 while maintaining the initial temperature of the discharge through a tool applying a 25 mm parallel plate type shear force. s) was measured by the Physica Rheometer, and the state of melt viscosity (extrusion state) was evaluated according to the following criteria.

(Double-circle): A melt viscosity is favorable, and winding is favorable to a cooling drum. (Circle): A melt viscosity is a little low, but winding is difficult. ×: A melt viscosity is too low, and winding is impossible.

(10) Initial tensile strength (kgf / mm 2) MD, TD: 150 mm long, 10 mm wide film sample was aged for 24 hours in an atmosphere of temperature 20 ℃, humidity 65% RH, UTM (manufacturer: INSTRON according to ASTM D638) Tensile strength was measured using a universal testing machine under a drawing speed of 300 mm / min and a distance of 100 mm between grips. The average value of 5 tests in total was expressed as a result. The longitudinal direction of the film was indicated by MD, and the transverse direction by TD.

(11) Elongation (%) MD, TD: The elongation at break of the film under the same condition as the tensile strength of the above (6) was measured and the average value of the test was measured five times in total. The longitudinal direction of the film was indicated by MD, and the transverse direction by TD.

(12) F5 (kgf / mm &lt; 2 &gt;) MD, TD: The tangent of the tangent line at the point of stress at the time of 5% deformation in the stress-strain curve obtained in the above- % The value of the stress at the time of elongation was obtained, and the average value of the test of 5 times in total was expressed as a result value. The longitudinal direction of the film was indicated by MD, and the transverse direction by TD.

(13) F100 (kgf / mm &lt; 2 &gt;) MD: The slope of the tangent line at the point of stress at the time of 100% deformation in the stress-strain curve obtained by the tensile test of the above (6) The value of the stress at the time of the test was obtained, and the average value of the test of the total of 5 times was expressed as a result value. Only the longitudinal MD of the film was measured.

(14) Young's modulus (kgf / mm2) MD, TD: The same specimen as the tensile test of (6) above, using a UTM (manufacturer: INSTRON) universal testing machine according to ASTM D638, stretching speed 300mm / min, distance between grips 100mm Young's modulus was measured by. The average value of 5 tests in total was expressed as a result. These values of the Young's modulus, particularly the Young's modulus measured in the length and width directions, correspond to the flexibility of the film, and the lower the Young's modulus value is, the better the flexibility. The longitudinal direction of the film was indicated by MD, and the transverse direction by TD.

(15) Wavy pattern (horizontal line): When the film is extruded by compounding two resins or resins and plasticizers having different molecular weights, the degree of the wave pattern generated by the difference in melt viscosity is expressed by the following formula And evaluated according to the standards.

◎: No wave pattern

○: less than 3 wave patterns

×: 5 or more wave patterns

(16) 100 ° C. weight change rate (%): The film samples were aged in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH for 24 hours, and the weight before heat treatment was measured. Thereafter, the resultant was treated in a hot air oven at 100 ° C for 60 minutes, aged under the same conditions as before treatment, and then weighed. The results were calculated by weight ratios before and after the heat treatment before the treatment.

(17) Pin Hole Generation and Bleed-Out Characteristics: After the heat treatment of (12), the surface of the film sample was observed to determine whether pin hole was generated. In addition, the degree to which the low molecular weight plasticizer component bleeded out to the film surface by the touch was evaluated according to the following criteria in an A4 size film sample.

◎: No pin hole and bleed out

○: Within 5 pin holes or bleed out but not severe

×: 5 or more pin holes or severe bleed out

(18) Haze (%) and transmittance (%): The film sample was aged for 24 hours in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH in advance, and then subjected to another using a Haze meter (model name: NDH2000, Japan) in accordance with JIS K7136. It measured about three parts and computed the average value as a result.

(19) Blocking resistance: Using the COLOLOITP type (manufactured by Coolz Co., Ltd.) of the stamping foil, the antistatic surface and the printing surface of the film sample were aligned with each other, and left for 24 hours at a temperature of 40 ° C and a pressure of 1 g / cm 2, The blocking state of the antistatic layer and the printing surface was observed. Based on these observations, the blocking resistance between the antistatic layer (A layer) and the print surface of the in-mold foil transfer foil was evaluated. At this time, up to ○ satisfies the practical performance.

◎ ： No change

○: slight change in surface (5% or less)

X: 5% or more peeling

(20) Yellowness of film: The film sample is crushed by a crusher, dehumidified, dried and crystallized at 120 ° C, and then melted at about 200 ° C by a small single screw extruder (Rheomics 600 extruder, Haake) and chip again. It was made. The difference of the color-b value of the chip before and after the film processing was measured, and the yellowing degree was evaluated by the following criteria.

◎: almost no yellowing below 2,

○: yellowing slightly below 5,

X: More than 5 severe yellowing.

(21) Organic carbon content rate of biomass origin (% C _bio ): Based on ASTM D6866, the organic carbon content rate of biomass origin is measured from the biomass origin material content test by a radiocarbon concentration (Percent Modern; C14). It was.

The raw materials used in the following examples and comparative examples are as follows:

One. Polyether series Polyol  Repeating units (or (co) polymers) or their counterparts

- PPDO 2.4: poly (1,3-propanediol); Number average molecular weight 2,400

            Polyols consisting solely of organic carbon of biomass origin

PPDO 1.0: poly (1,3-propanediol); Number average molecular weight 1,000

            Polyols consisting solely of organic carbon of biomass origin

PTMEG 3.0: polytetramethylene glycol; Number average molecular weight 3,000

PTMEG 2.0: polytetramethylene glycol; Number average molecular weight 2,000

PTMEG 1.0: polytetramethylene glycol; Number average molecular weight 1,000

             Polyols consisting solely of organic carbon of biomass origin

PEG 8.0: polyethylene glycol; Number average molecular weight 8,000

PBSA 11.0: aliphatic polyester polyols made of 1,4-butanediol and condensates of succinic acid and adipic acid; Number average molecular weight 11,000

2. Diisocyanate  Compound (or trifunctional or higher isocyanate)

HDI: hexamethylene diisocyanate

D-L75: Bayer Desmodur L75 (TRIMETHYLOL PROPANE + 3 toluene diisocyanate)

3. Lactide  Monomer

- L-lactide or D-lactide: Optical purity of 99.5% or more from Purac

Monomers composed solely of organic carbon of biomass origin

4. Antioxidants etc

TNPP: Tris (nonylphenyl) phosphite

U626: Bis (2,4-di-tbutylphenyl) Pentaerythritol Diphosphite

S412: Tetrakis [methane-3- (laurylthio) propionate] methane

PEPQ: (1,1'-Biphenyl) -4,4'-Diylbisphosphonous acid tetrakis [2,4-bis (1,1-dimethylethyl) phenyl] ester

I-1076: octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate

O3: Bis [3,3-bis- (4'-hydroxy-3'-tert-butyl-phenyl) butanoic acid] glycol ester

A. Polylactic acid  Preparation of Resin A-F

An 8 L reactor equipped with a nitrogen gas inlet tube, agitator, catalyst inlet, outlet condenser and vacuum system was charged with the catalyst with the components and contents as shown in Table 1 below. 130ppmw of Dibutyltin Dilaurate was used as the catalyst. The urethane reaction was carried out at a reactor temperature of 70 ° C. for 2 hours under a nitrogen stream, and 4 kg of L- (or D-) lactide was added thereto to carry out 5 times of nitrogen flushing.

Thereafter, the temperature was raised to 150 ° C. to completely dissolve the L- (or D-) lactide, and 120ppmw of the catalyst Tin 2-ethylhexylate to 500 ml of toluene was added to the reaction vessel through the catalyst inlet. The reaction was carried out at 185 ° C. for 2 hours under 1 kg of nitrogen pressurization, and 200 ppmmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Subsequently, unreacted L- (or D-) lactide (about 5 weight of the initial dose) was removed by vacuum until it reached 0.5torr. Molecular weight characteristics, Tg, Tm and% C _bio of the obtained resin was measured and shown in Table 1.

B. Polylactic acid  Preparation of Resin L

To an 8 liter reactor equipped with a nitrogen gas inlet tube, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system, polyol and 4 kg of L-lactide as shown in Table 1 were added thereto, and five times of nitrogen flushing were performed. The temperature was raised to 150 ° C. to completely dissolve the L-lactide, and the catalyst Tin 2-ethylhexylate 120ppmw was diluted with 500 ml of toluene and added into the reaction vessel through the catalyst inlet. Subsequently, the reaction was carried out at 185 ° C. for 2 hours under 1 kg of nitrogen pressurization, and 200 ppmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Unreacted L-lactide was removed by vacuum until it reached 0.5torr. Molecular weight characteristics, Tg, Tm and% C _bio of the obtained resin was measured and shown in Table 1.

C. Polylactic acid  Preparation of Resin M

Into an 8 liter reactor equipped with a nitrogen gas introduction tube, a stirrer, a catalyst inlet, an outlet condenser, and a vacuum system, 6 g of 1-Dodecanol and 4 kg of L-lactide as shown in Table 1 were added thereto, followed by five times of nitrogen flushing. . The temperature was raised to 150 ° C. to completely dissolve the L-lactide, and the catalyst Tin 2-ethylhexylate 120ppmw was diluted with 500 ml of toluene and added into the reaction vessel through the catalyst inlet. Subsequently, the reaction was carried out at 185 ° C. for 2 hours under 1 kg of nitrogen pressurization, and 200 ppmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Unreacted L-lactide was removed by vacuum until it reached 0.5torr. Molecular weight characteristics, Tg, Tm and% C _bio of the obtained resin was measured and shown in Table 1.

D. Polylactic acid  Preparation of Resin O

Into an 8 L reactor equipped with a nitrogen gas inlet tube, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system, PBSA polyol (polyester polyol) and HDI as shown in Table 1 were charged and subjected to nitrogen flushing five times. 130ppmw of Dibutyltin Dilaurate was used as the catalyst. Urethane reaction was carried out for 2 hours at a reactor temperature of 190 ° C. under a nitrogen stream, 4 kg of L-lactide was added, completely dissolved L-lactide at 190 ° C. in a nitrogen atmosphere, and compared to the total reactant content through a catalyst inlet. 120ppmw of addition polymerization catalyst Tin 2-ethylhexylate and 1000ppmw of Dibutyltin Dilaurate as an Ester and / or Ester amide exchange catalyst were diluted in 500ml of toluene and added to the reaction vessel. The reaction was carried out at 190 ° C. for 2 hours under 1 kg of nitrogen pressurization, and 200 ppmmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Subsequently, unreacted L-lactide (about 5 weight of the initial dose) was removed via vacuum until it reached 0.5torr. Molecular weight characteristics, Tg, Tm and% C _bio of the obtained resin was measured and shown in Table 1.

E. Polylactic acid  Preparation of Resin P

To an 8 liter reactor equipped with a nitrogen gas inlet tube, agitator, catalyst inlet, outlet condenser and vacuum system, PEG and 3.6 kg of L-lactide and 0.4 kg of D-lactide as shown in Table 1 were added. Ash nitrogen flushing was performed. The temperature was raised to 150 ° C. to completely dissolve the lactide, and the catalyst Tin 2-ethylhexylate 120ppmw was diluted with 500 ml of toluene and added to the reaction vessel through the catalyst inlet. Subsequently, the reaction was carried out at 185 ° C. for 2 hours under 1 kg of nitrogen pressurization, and 200 ppmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Unreacted L-lactide (about 5 weight of initial dose) was removed via vacuum until 0.5torr was reached. Thereafter, HDI and 120ppmw of Dibutyltin Dilaurate 120ppmw of 130ppmw of the catalyst were diluted with 500 ml of toluene and added into the reaction vessel through the catalyst inlet. The reaction was carried out at 190 ° C. for 1 hour under a nitrogen atmosphere, and the molecular weight characteristics, Tg, Tm, and% C _bio of the obtained resin were measured and shown in Table 1 below.

F. Polylactic acid  Preparation of Resin Q

To an 8 liter reactor equipped with a nitrogen gas inlet tube, agitator, catalyst inlet, outlet condenser and vacuum system, PEG and 3.6 kg of L-lactide and 0.4 kg of D-lactide as shown in Table 1 were added. Ash nitrogen flushing was performed. The temperature was raised to 150 ° C. to completely dissolve the lactide, and the catalyst Tin 2-ethylhexylate 120ppmw was diluted with 500 ml of toluene and added to the reaction vessel through the catalyst inlet. Subsequently, the reaction was carried out at 185 ° C. for 2 hours under 1 kg of nitrogen pressurization, and 200 ppmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Unreacted L-lactide (about 5 weight of initial dose) was removed via vacuum until 0.5torr was reached. Thereafter, D-L75 and 120 ppm Dibutyltin Dilaurate 120 ppmmw of catalyst 130ppmw were diluted with 500 ml of toluene and added into the reaction vessel through the catalyst inlet. The reaction was carried out at 190 ° C. for 1 hour under a nitrogen atmosphere, and the molecular weight characteristics, Tg, Tm, and% C _bio of the obtained resin were measured and shown in Table 1 below.

G. Film Example  1-5, Comparative Example  Preparation of 1 and 5 to 7

The polylactic acid resins prepared in A to E, M and O to Q were dried under reduced pressure at 80 ° C. under a vacuum of 1 torr for 6 hours, followed by extrusion shown in Table 2 in a 30 mm diameter single screw extruder equipped with a T die. Extruded onto a sheet under temperature conditions. The unstretched film was produced by electrostatically casting on the drum cooled to 5 degreeC. After stretching the unstretched film three times in the longitudinal direction between heating rolls under the stretching conditions shown in Table 2, the stretched film was fixed with a clip and drawn into the tenter four times in the width direction, and then fixed in the width direction. In the state, heat treatment was performed at 120 ° C. for 60 seconds. Through this, a biaxially stretched polylactic acid resin film having a thickness of 20 μm was obtained. The evaluation results of the obtained film are shown together in Table 2

H. film Example  6, Comparative Example  Manufacture of 2-4

The resin mixture or polyol shown in Table 2 was dried under reduced pressure at 80 ° C. under a vacuum of 1 torr for 6 hours, and then melt-kneaded and chipped at a temperature of 190 ° C. in a twin screw kneading extruder. After drying the composition under reduced pressure at 80 ° C. for 6 hours under a vacuum of 1 torr, a biaxially stretched polylactic acid resin film having a thickness of 20 μm was prepared in the same manner as the method of G, and the evaluation results are shown in Table 2 together.

Resin A Resin B Resin C Resin D Resin E Resin F Resin L Resin M Resin O Resin P Resin Q PPDO 2.4 (g) 378.8 PPDO 1.0 (g) 209.5 PTMEG 3.0 (g) 386.9 PTMEG 2.0 (g) 755.5 1560 PTMEG 1.0 (g) 184.8 PEG 8.0 (g) 2400 800 800 PBSA 11.0 (g) 800 HDI (g) 13.1 21.2 30.5 15.2 44.4 120 9.5 10.1 D-L75 (g) 14.9 NCO / OH 0.6 0.8 0.9 0.50 0.70 0.92 0.8 0.7 0.65 OHV (KOHmg / g) 10 6 4 20 6 2 47 3 5.5 5.5 TNPP (g) 4 U626 (g) 2 3 6 9.6 3 PEPQ (g) 4 S412 (g) 2 I-1076 (g) One O3 (g) 2 L-lactide (g) 4000 4000 4000 4000 4000 4000 4000 3600 3600 D-lactide (g) 4000 4000 400 400 Antioxidant Content (ppmw) 1000 1000 1000 1500 1500 2400 0 750 0 0 0 IV (dl / g) 0.95 1.35 1.52 0.64 0.92 1.20 0.2 1.55 Mn (× 1,000, g / mol) 75 122 148 60 70 68 14 128 65 60 55 Mw (× 1,000, g / mol) 148 245 315 115 149 140 26 295 185 150 215 MWD 1.97 2.01 2.13 1.92 2.13 2.05 1.86 2.30 2.85 2.50 3.91 Tg (占 폚) 49 42 54 55 31 10 15 65 18 22 17 Tm (占 폚) 170 168 172 173 164 156 130 176 85, 165 145 142 Color b 4 3 2 5 6 4 5 4 13 6 6 Polyurethane polyol repeat unit content (wt%) 10% 10% 6% 5% 17% 30% 39% 0% 18% 18% 17% Residual monomer content (% by weight) 0.45 0.4 0.3 0.65 0.55 0.68 8 0.3 2.5 1.2 1.5 Weight percent of biomass C
(ASTM D6866) 89.2 99.1 98.5 98.8 81.6 66.2 57.7 98.8 82.6 78.2 80.3

Referring to Table 1, the resins A to F are poly (1,3-propanediol) having a molecular weight of 1,000 to 2,400 or polytetramethylene glycol having a number average molecular weight of 1,000 to 3,000 so that the NCO / OHV is 0.5 to 0.99. Urethane reaction with 6-Hexametylene diisocyanate to obtain a polyurethane polyol repeating unit (or (co) polymer) in which the polyether polyol repeating units such as poly (1,3-propanediol) are linearly connected, and are used as initiators and soft segments. It corresponds to the polylactic acid resin (block copolymer) obtained using. In addition, the polylactic acid resin is polymerized after being mixed with a specific content of the antioxidant, it is confirmed that yellowing is suppressed to show a low color b value and the residual lactide content is also low. This polylactic acid resin was identified to contain% C _bio in an amount of about 60% by weight or more, using a monomer comprising organic carbon of biomass origin determined according to standard ASTM D6866.

In the polylactic acid resin, the polyurethane polyol repeating unit (or (co) polymer) may have a value of OHV 2 to 20, and thus may serve as an initiator in the polymerization process for forming the polylactic acid repeating unit. This was confirmed. In addition, the final polylactic acid resins A to F have a weight average molecular weight of 100,000 to 400,000, a molecular weight distribution of 1.80 to 2.15, a Tg of 10 to 55 ° C, and a Tm of 155 to 178 ° C. It was confirmed that film formation was possible because the melt viscosity was higher than or equal to ℃. In addition, the residual lactide content in the resin was also low as less than 1% by weight, and the color b value was also lowered to less than 6, and it was confirmed that yellowing was hardly observed.

In contrast, the resin L attempts to prepare a polylactic acid resin by using polyethylene glycol having a molecular weight of 8000 as an initiator in the ring-opening polymerization of L-lactide without a urethane reaction. However, in such a case, the OHV of the initiator was high, and a polylactic acid resin having a desired weight average molecular weight could not be obtained. In addition, it was confirmed that the resin L did not have an antioxidant added, so the residual lactide content was also very high, the polymerization conversion was low, and the melt viscosity was too low at the film extrusion temperature of 200 ° C. or higher, so that film production alone was not possible. In addition, the resin L was found to have a% C _bio content of less than 60% by weight.

Resin M is a polylactic acid resin prepared by ring-opening polymerization of L-lactide using a small amount of 1-Dodecanol as an initiator according to a general polylactic acid resin production method without introducing a softening component (polyurethane polyol repeating unit) in the resin. Corresponding. In the case of such a polylactic acid resin, the film was independently produced at a film extrusion temperature of 200 ° C. or higher. However, it was confirmed that such polylactic acid resin had a considerably wide molecular weight distribution of 2.30.

Resin O also uses polyurethanes formed from polyester polyol repeating units, such as PBSA, rather than polyether polyol repeating units as the softening component in the resin, while the ring-opening polymerization catalyst, the transesterification catalyst and / or the ester amide exchange catalyst In the presence of, a polylactic acid copolymer obtained by copolymerizing the polyurethane and lactide. In such a polylactic acid copolymer, the polyurethane is randomly introduced into a small segment size and is copolymerized with the polylactic acid repeating unit while the ester and / or ester amide exchange reaction takes place. This resin O was found to have a considerably wide molecular weight distribution of 2.85 and a relatively low Tm. In addition, it was confirmed that the resin O also has a relatively high residual lactide content and no color b value due to the addition of antioxidants.

Finally, the resins P and Q add the lactide to the polyether polyol repeating unit first to prepare a prepolymer copolymerized with the polyether polyol repeating unit and the polylactic acid repeating unit, and then chain extend the prepolymer with a diisocyanate compound. Corresponds to the copolymer (resin P) and the branched copolymer (resin Q) in which the prepolymers are reacted with at least trifunctional isocyanate compounds. These resins P and Q have a wide molecular weight distribution of 2.50 and 3.91, and it is confirmed that Tm is also relatively low. In addition, it was confirmed that the resin O had a relatively high residual lactide content because no antioxidant was added and the color b value was considerably high.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Resin 1 (wt%) A 100 B 100 C 100 D 100 E 100 F 50 M 100 L 40 PDO 10 PBSA 10 O 100 P 100 Q 100 Resin 2 (wt%) M 50 M 60 M 90 M 90 Extrusion Temperature (℃) 220 230 240 200 200 230 240 200 200 200 200 200 240 Melt Viscosity (Pas) 1100 1600 2100 580 1000 1400 2000 250 1200 1400 1400 1200 1800 Extrusion State ◎ ◎ ◎ ○ ◎ ◎ ◎ X ◎ ○ ◎ X X Drawing temperature (℃) 81 80 80 70 80 70 80 80 80 80 80 80 80 Elongation time (sec) 20 20 20 30 20 20 20 20 20 20 20 20 20 Draw ratio 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 3 × 4 Film thickness (um) 20 20 20 21 20 20 20 20 20 20 20 20 20 Initial tensile strength (kgf / mm &lt; 2 &gt;) MD 10 15 18 10 12 15 20 2.5 15 9 7 6 14 Initial tensile strength (kgf / mm &lt; 2 &gt;) TD 13 20 25 14 14 20 26 3.1 18 10 8 7 17 Tensile Strength Total (kgf / ㎠) 23 35 43 24 26 35 46 5.6 33 19 15 13 31 Elongation (%) MD 117 140 120 144 160 150 124 152 145 135 212 210 85 Elongation (%) TD 70 70 75 78 98 101 86 89 66 98 105 98 65 F5 (kgf / mm2) MD 5.3 8 10 5 4.8 9.0 9.8 1.5 8.7 7.9 5 6 11 F5 (kgf / ㎡) TD 8.1 10 11 7.7 7.8 11.8 12 2.1 11 9.8 6.5 6.8 13 F100 (kgf / ㎡) MD 8.1 15 16 6.7 12 18.2 17 1.8 5.6 6.1 4.2 4.5 8.8 Young's modulus (kgf / mm2) MD 236 230 330 212 180 190 386 179 338 327 150 160 302 Young's modulus (kgf / ㎡) TD 295 280 418 319 235 210 460 241 419 412 165 175 355 Young's modulus Total (kgf / ㎟) 531 510 748 531 415 400 846 420 757 739 315 335 657 Wave pattern ◎ ◎ ◎ ◎ ◎ ◎ ◎ X ○ ○ ◎ X X Pin hole occurrence ◎ ◎ ◎ ◎ ◎ ◎ ◎ X ◎ ○ X X X 100% Weight change rate (%) 0.2 0.2 0.2 0.3 0.4 0.3 0.2 6 5.1 5.5 7.2 3.8 4.7 Bleed-out ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ X X ○ ○ ○ Haze (%) 0.2 0.2 0.2 0.3 0.3 0.4 0.7 0.7 10 14 2.1 1.1 1.8 Transmittance (%) 94 94 94 94 93 94 94 87 89 81 84 84 85 My blocking ability ◎ ◎ ◎ ◎ ○ ○ ◎ X ○ ○ X X X Yellow coloring degree ◎ ◎ ◎ ◎ ◎ ◎ ◎ X X X X X X

 Referring to Table 2, Examples 1 to 5 has a content of the softening component (polyurethane polyol repeating unit) in the polylactic acid resin is 5 to 35wt%, low color b value, and contains an appropriate amount of antioxidant It is manufactured using the polylactic acid resin composition of this invention which has physical properties, such as a weight average molecular weight 100,000-400,000, molecular weight distribution 1.80-2.15, and Tm 155-178 degreeC. In addition, Example 6 is also prepared using a composition in which a polylactic acid resin (resin F) and a general polylactic acid resin (resin M) and an antioxidant are mixed within the scope of the present invention.

The films of Examples 1 to 6 all have excellent mechanical properties with an initial tensile strength of 10 kgf / mm 2 or more in the length and width directions, and have excellent flexibility with a Young's modulus in the length and width directions of 750 kgf / mm 2 or less. Indication was confirmed. Moreover, it was confirmed that such a Young's modulus sum was not too low, but maintained an appropriate range, and stiffness also showed an appropriate level. In addition, the weight change rate when treated in a 100 ° C. hot air oven for 1 hour is 3 wt% or less, the haze is 3% or less, the transmittance is 85% or more, and the blocking resistance is also excellent, such as transparency, haze, blocking resistance, and the like. It was confirmed that various physical properties such as heat resistance were excellent. In addition, the films of Examples 1 to 6 were also good in appearance and excellent in thermal stability, so that even after the film extrusion process, the color b value change (yellowing coloration) was not severe.

On the other hand, the film of Comparative Example 1 made of a general polylactic acid resin M had a total flexibility of the length and width direction Young's modulus exceeding 750 kgf / mm 2, which was insufficient in flexibility, and thus it was difficult to be used as a packaging film. In addition, in the case of the film of Comparative Example 2 prepared by using the resin M and the resin L together, the difference in melt viscosity between the two resins is too large, the extrusion state is poor, and the problem that the wavy pattern occurs in the final film also occurred . Moreover, due to the high residual lactide dilution, pin holes were generated on the film, resulting in poor film appearance, problems such as blocking resistance, and poor initial tensile strength, transmittance, and yellowing coloration.

In Comparative Examples 3 and 4, without using a polyurethane polyol repeating unit which is a softening component in the resin, poly (1,3-propanediol) having a number average molecular weight of 2,400 and 1,4 having a number average molecular weight of 11,000, respectively, as a plasticizer component -Butanediol and an aliphatic polyester polyol made of a condensate of succinic acid and adipic acid are simply compounded and mixed into resin M into a film. In the films of Comparative Examples 4 and 5, the degree of dispersion of the plasticizer component in the resin was not perfect, and thus the haze of the film was high, the yellowing color was poor, and the plasticizer component bleeded out from the surface of the film after a lapse of time. .

In addition, the film of Comparative Example 5 had a polyester polyol repeating unit introduced therein and a broad molecular weight distribution &Lt; / RTI &gt; Such films showed relatively good flexibility as the softening component polyurethane was randomly introduced into a small segment size, but as polylactic acid repeating units were also introduced into a relatively small segment size, the film exhibited poor heat resistance due to low Tm and blocking. Difficulties in filming were identified as a problem. In addition, the low compatibility of the polyester polyol and polylactic acid used for the formation of the softening component was found to result in high haze value and low transparency of the film, and the molecular weight was determined by the ester and / or ester amide exchange reaction during resin production. It was confirmed that the distribution was wide, resulting in non-uniform melting characteristics, poor film extrusion state, and deterioration of mechanical properties.

The films of Comparative Examples 6 and 7 include a resin obtained by urethane-reacting a prepolymer obtained by addition polymerization of lactide to a polyether polyol with a diisocyanate or a trifunctional or higher isocyanate compound, which also has a broad molecular weight distribution and repeats a polyether polyol. The units are linearly connected by urethane bonds, and together with these, they fail to meet the structural characteristics of the present invention including a relatively high molecular weight polylactic acid repeating unit as a hard segment. These films were found to exhibit non-uniform melt viscosity and poor mechanical properties. In addition, the blocking characteristics of the hard and soft segments in the resin were deteriorated, indicating low heat resistance due to low Tm and the like, and it was confirmed that film formation was difficult due to blocking problems.

In addition, due to the high residual lactide content, relatively high color b value, and the like of the films of Comparative Examples 5 to 7, significant appearance defects were observed even in the film state, and 100 ° C. weight change rate, which was inappropriate for commercial application, was observed. Moreover, as the films of Comparative Examples 5 to 7 require the use of an excessive amount of catalyst during the preparation of the resin, it appears that the decomposition of the polylactic acid resin is induced during the production or use of the film. It was confirmed that the stability of the film was poor by increasing the rate of change of weight at the production or high temperature.

Claims (17)

A hard segment including a polylactic acid repeating unit represented by Formula 1 below;
The polyether-based polyol repeating units of the formula (2) includes a soft segment including a polyurethane polyol repeating unit linearly connected via a urethane bond,
A polylactic acid resin having an organic carbon content rate (% C _bio ) of biomass origin defined by the following Formula 1 being 60% by weight or more; And
A polylactic acid resin composition comprising an antioxidant in an amount of 100 to 3000 ppmw with respect to the amount of the monomer added to form the polylactic acid repeating unit:
[Chemical Formula 1]

(2)

[Formula 1]
% C = _Bio (poly ¹⁴ C isotope ratio by weight of the ¹² C isotope of carbon atoms of the lactic acid resin) / ⁽¹⁴ C isotope ratio by weight of the ^bio-12 C isotope of carbon atoms of the mass origin standard)
In the general formulas (1) and (2), A is a linear or branched alkylene group having 2 to 5 carbon atoms, m is an integer of 10 to 100, and n is an integer of 700 to 5000.
The polylactic acid resin composition of claim 1, wherein the content of ¹⁴ C isotopes in carbon atoms of the polylactic acid resin is 7.2 × 10 ⁻¹¹ wt% to 1.2 × 10 ⁻¹⁰ wt%.
The polylactic acid resin composition according to claim 1, wherein the soft segment has an organic carbon content rate (% C _bio ) of biomass origin as defined by Equation 1 above 70 wt%.
The polylactic acid resin composition of claim 1, wherein the polylactic acid resin has a number average molecular weight of 50,000 to 200,000 and a weight average molecular weight of 100000 to 400000.
The polylactic acid resin composition of claim 1, wherein the polylactic acid resin has a glass transition temperature (Tg) of 8 to 55 ° C and a melting temperature (Tm) of 155 to 178 ° C.
The polylactic acid resin composition according to claim 1, wherein the polyether polyol repeating units are linearly connected through a urethane bond formed by the reaction of a hydroxyl group and a diisocyanate compound at the terminal to form a polyurethane polyol repeating unit.
The polylactic acid resin composition of claim 6, wherein the polylactic acid resin comprises a block copolymer in which the terminal carboxyl group of the polylactic acid repeating unit included in the hard segment is connected by an ester bond to the terminal hydroxyl group of the polyurethane polyol repeating unit.
The method of claim 7, wherein the polylactic acid resin is the block copolymer; And a polylactic acid repeating unit which is not bonded to the polyurethane polyol repeating unit.
The polylactic acid resin composition of claim 1, wherein the polyether polyol repeating unit has a number average molecular weight of 450 to 9000.
7. The polylactic acid resin composition according to claim 6, wherein the reaction molar ratio of the terminal hydroxyl groups of the polyether polyol repeating units: the isocyanate group of the diisocyanate compound is 1: 0.50 to 1: 0.99.
The polylactic acid resin composition of claim 1, wherein the polylactic acid resin includes 65 to 95 parts by weight of the hard segment and 5 to 35 parts by weight of the soft segment based on 100 parts by weight of the polylactic acid resin.
The polylactic acid resin composition according to claim 1, which exhibits a color-b value of less than six.
The polylactic acid resin composition according to claim 1, wherein less than 1% by weight of monomers remain with respect to the weight of the polylactic acid resin.
The polylactic acid resin composition of claim 1, wherein the antioxidant comprises at least one antioxidant selected from the group consisting of a Hindered phenol antioxidant, an amine antioxidant, a thio antioxidant, and a phosphite antioxidant.
Packaging film containing the polylactic acid resin composition of claim 1.
The packaging film of claim 15 having a thickness of 5 to 500 μm.
16. The weight change rate according to claim 15, wherein the total Young's modulus in the length and width directions is 350 to 750 kgf / mm 2, the initial tensile strength is 10 kgf / mm 2 or more, and the weight change rate when treated in a 100 ° C. hot air oven for 1 hour. The packaging film of 3.0 wt%, haze of 3% or less, and transmittance | permeability of 85% or more.