KR20180124813A - Polylactic acid resin composition and packaging film - Google Patents

Abstract

The present invention relates to a polylactic acid resin composition which not only exhibits improved flexibility, but also has various excellent physical properties such as mechanical properties, transparency, heat resistance, blocking resistance, and film processing ability, and thus can be usefully used as a packaging material and is environmentally friendly; and to a packaging film containing the polylactic acid resin composition. The polylactic acid resin composition comprises: a polylactic acid resin which includes a hard segment comprising a predetermined polylactic acid repeating unit and a soft segment comprising a polyurethane polyol repeating unit in which certain polyether polyol repeating units are linearly connected via a urethane bond, and which has the organic carbon content (% C bio) of biomass origin is 60 wt% or more; and a predetermined amount of an antioxidant.

Description

TECHNICAL FIELD [0001] The present invention relates to a poly (lactic acid resin composition)

The present invention relates to a poly (lactic 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 formability, and can be usefully used as packaging materials, To a resin composition and a packaging film comprising the resin composition.

Crude oil-based resins such as polyethylene terephthalate, nylon, polyolefin, or flexible 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 such a poly (lactic acid) resin is insufficient in heat resistance and mechanical properties compared to a crude oil-based resin, there is a limit to the field or application to which it can be applied. Particularly, attempts have been made to apply poly (lactic acid) resin as a packaging material for packaging films and the like, but such applications are limited due to the low flexibility of the poly (lactic 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, in the case of providing a packaging film or the like containing a polylactic acid resin by introducing a plasticizer or the like in a previously known method, it is necessary to introduce a large amount of a plasticizer or the like in order to improve flexibility. Biodegradability or environment-friendly properties of the product.

Accordingly, development of packaging films for polylactic acid resin films having excellent properties such as mechanical properties, transparency, heat resistance, blocking resistance and film processability and being useful for packaging materials and exhibiting environmentally friendly properties has been developed This is continuously being requested.

The present invention provides a poly (lactic acid) resin composition which exhibits improved flexibility and is excellent in various physical properties such as mechanical properties, transparency, heat resistance, blocking resistance and film processability, and can be effectively used as a packaging material and has environmentally friendly properties .

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

The present invention relates to a hard segment comprising a polylactic acid repeating unit represented by the following formula (1) and a soft segment containing a polyurethane polyol repeating unit in which polyether polyol repeating units represented by the following formula (2) are linearly connected through an urethane bond , A polylactic acid resin having an organic carbon content (% C _bio ) of biomass origin, defined by the following formula 1, of 60% by weight or more; And

Wherein the amount of the monomer added to form the polylactic acid repeating unit is 100 to 3000 ppmw.

[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.

Further, the present invention provides a packaging film comprising the poly (lactic acid) resin composition.

Hereinafter, a poly lactic acid resin composition according to a specific embodiment of the present invention and a packaging film comprising the same will be described.

According to an embodiment of the present invention, there is provided a polyurethane foam comprising a hard segment including a polylactic acid repeating unit represented by the following formula (1) and a polyurethane polyol repeating unit having a polyether polyol repeating unit represented by the following formula (2) A polylactic acid resin containing a soft segment and having an organic carbon content (% C _bio ) of biomass origin defined by the following formula 1 of not less than 60% by weight; And

Wherein the polylactic acid resin composition comprises an antioxidant in an amount of 100 to 3000 ppmw based on the amount of monomer added for formation of 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 poly (lactic acid) resin composition includes a predetermined poly (lactic acid) resin and a certain amount of an antioxidant, and the poly (lactic acid) resin basically contains the poly (lactic acid) repeating unit represented by the above formula 1 as a hard segment. In addition, the poly (lactic acid) resin includes a polyurethane polyol repeating unit as a soft segment. The polyurethane polyol repeating unit is a repeating unit in which the polyether polyol repeating units represented by the above-mentioned formula (2) are urethane bonds (-C (= O) ) In a linear manner.

These polylactic acid resins basically exhibit biodegradability inherent in biomass-based resins as they contain polylactic acid repeating units as hard segments. Further, as a result of experiments conducted by the present inventors, it has been found that, by including the polyurethane polyol repeating unit as a soft segment, the polylactic acid resin exhibits greatly improved flexibility (for example, a total of relatively low Young's modulus, As well as to provide a film which exhibits excellent transparency and low haze value. 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. Accordingly, it has been found that the poly (lactic acid) resin enables to provide a film exhibiting excellent transparency and low haze value, with improved flexibility. Moreover, the poly (lactic acid) resin can exhibit the above-described effects without increasing the content of the soft segment for improving the flexibility.

In addition, the polylactic acid resin may exhibit biodegradability and environment-friendly characteristics peculiar to the biomass-based resin by including the polylactic acid repeating unit as a hard segment. Moreover, as described above, it is not necessary to increase the content of the soft segment so much to improve flexibility, and it may include a hard segment derived from a relatively high content of biomass-based resin, for example, polylactic acid resin .

Accordingly, the poly (lactic acid) resin contained in the resin composition of one embodiment has an organic carbon content (% C _bio ) of biomass origin defined by the above formula 1 of not less than about 60% by weight, or not less than about 70% About 80% by weight or more, about 85% by weight or more, about 90% by weight or more, or about 95% by weight or more.

The method for measuring the organic carbon content (% C _bio ) from the biomass source according to the formula 1 may be, for example, according to the method described in the ASTM D6866 standard. The technical meanings and measurement methods of the organic carbon content (% C _bio ) will be described in more detail as follows.

In general, unlike organic materials such as resins derived from fossil raw materials, organic materials such as resins derived from biomass (biomass) are known to contain isotope ^14C . More specifically, all organic materials taken from living organisms such as animals or plants contain ¹² C (about 98.892 wt%), ¹³ C (about 1.108 wt%) and ¹⁴ C (about 1.2 x 10 ^-10 wt% , And it is known that the ratio of each isotope is kept constant. This is equal to the ratio of each isotope in the atmosphere, and this isotope ratio remains constant, as living organisms continue to metabolize and continuously exchange carbon atoms with the external environment.

On the other hand, ¹⁴ C is a radioactive isotope and its content may decrease according to the elapse of time (t) according to the following formula (2).

[Formula 2]

n = no · exp (-at)

no denotes the initial number of atoms in the ¹⁴ C isotope, n denotes the number of remaining ¹⁴ C isotopes after t time, and a denotes the disintegration constant (or radioactive constant) associated with the half life.

In this equation 2, the half-life of the ¹⁴ C isotope is about 5730 years. Taking this half-life into consideration, the organic material taken from a living organism that continuously interacts with the external environment, that is, the organic material such as resin derived from biomass (biomass), has a substantially constant 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 , can be maintained.

On the other hand, fossil fuels such as coal or petroleum have been blocked from carbon exchange with the external environment for over 50,000 years. Accordingly, when a resin such as an organic material derived from the fossil raw material is hayeoteul estimated according to the formula (2), comprising a ¹⁴ C isotope to 0.2% of the initial content (atomic number), substantially not containing the ¹⁴ C isotope Do not.

Equation 1 takes the above-mentioned point into consideration, and the denominator can be a weight ratio of the isotope ¹⁴ C / ¹² C derived from biomass, for example, about 1.2 x 10 ^-12 , Lt; RTI ID = 0.0 > ¹⁴ C / ¹² C. < / RTI > As described above, while the carbon atoms derived from biomass maintain an isotope weight ratio of about 1.2 x 10 <" ^{12 &} gt ;, the carbon atoms derived from fossil fuels have a In the polylactic acid resin contained in the resin composition of the embodiment, the organic carbon content (% C _bio ) of the total carbon atoms originating from the biomass can be measured by the above formula (1). At this time, the content of each carbon isotope and the content ratio thereof (weight ratio) are described in ASTM D6866-06 standard (standard test method for determining the biological base content of a natural substance using radioactive carbon and isotope ratio mass spectrometry analysis) And can be measured according to one of the three methods. Suitably, the carbon atoms contained in the resin to be measured may be converted into a graphite or carbon dioxide gas form, measured by a mass spectrometer, or measured by liquid scintillation spectrometry. At this time, together with the mass spectrometer, two isotopes can be separated using an accelerator for separating ¹⁴ C ions from ¹² C ions, and the content and content ratio of each isotope can be measured by a mass spectrometer. Alternatively, the content and content ratio of each isotope may be determined using liquid scintillation spectroscopy, which is obvious to a person skilled in the art.

As the measured value of the organic carbon content (% C _bio ) of the thus derived formula 1 is about 60% by weight or more, the polylactic acid resin and the resin composition of one embodiment including the polylactic acid resin contain a larger amount of the resin derived from the biomass And carbon, and the polylactic acid resin and the resin composition of one embodiment can suitably exhibit unique environment-friendly characteristics and biodegradability.

More specifically, the poly (lactic acid) resin that satisfies such a high organic carbon content (% C _bio ) and the resin composition of one embodiment including the poly (lactic acid) resin can exhibit the environment-friendly characteristics described below.

Biochemicals such as poly lactic acid resins are biodegradable and have low carbon dioxide emissions and can reduce CO2 emissions by up to 108% compared to petrochemical products at present technology level and reduce energy for resin manufacturing by up to 50% can do. In addition, the production of bioplastics using biomass raw materials is expected to reduce CO2 emissions by up to 70% compared to the use of fossil raw materials, as calculated by the ISO 14000 compliant Life Cycle Analysis (LCA).

As a concrete example, according to NatureWorks, when manufacturing PET resin, 3.4 kg of carbon dioxide is emitted per kg, while polyol acid resin, which is a type of bio-plastic, generates only 0.77 kg of carbon dioxide per kg, resulting in a reduction effect of about 77% It is also known that energy use is only 56% of PET. However, in the case of a previously known poly (lactic acid) resin, application is limited due to low flexibility and the like, and when other components such as a plasticizer are included in order to solve this problem, there is a problem that the advantages as the bioplastics described above are greatly reduced.

However, since the polylactic acid resin and the resin composition of one embodiment including the polylactic acid resin satisfy the above-mentioned high organic carbon content (% C _bio ), it is possible to fully utilize the advantage as a bioplastic, And can be applied to various fields.

Accordingly, the polylactic acid resin that satisfies the above-described high organic carbon content (% C _bio ) and the resin composition of one embodiment including the same can take advantage of the bioplastics to exhibit environment-friendly characteristics that greatly reduce carbon dioxide generation amount and energy consumption. Such environment-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 contains a certain amount of antioxidant together with the above-mentioned polylactic acid resin. The inventors of the present invention have found that the content of such an antioxidant can provide a resin composition and a film which can suppress the yellowing of the polylactic acid resin and have a good appearance, thereby completing the present invention. To this end, the resin composition of one embodiment may have a content of about 100 to 3000 ppmw, or about 100 to 2000 ppmw, based on the amount of monomers (for example, lactic acid or lactide) for the formation of polylactic acid repeating units of the polylactic acid resin, , Or about 500 to 1500 ppmw, or about 1000 to 1500 ppmw of antioxidant. If the content of the antioxidant is too low, the polylactic acid resin may be yellowed by oxidation of a softening component such as the soft segment, and the appearance of the resin composition and the film may be poor. Also, when the content of the antioxidant is too high, the antioxidant may lower the polymerization rate of lactide and the like, so that the hard segment including the polylactic acid repeating unit may not be produced properly, and the mechanical properties of the polylactic acid resin Can be lowered.

Alternatively, in the case of using the resin composition of one embodiment containing the antioxidant in an optimized content, for example, the antioxidant may be added in an optimized amount at the time of polymerization for producing a polylactic acid resin, In the case of obtaining the resin composition of one embodiment, the conversion efficiency and the polymerization degree (degree of polymerization) of the poly (lactic acid) resin can be improved and the productivity can be increased. In addition, in the film-forming step for heating the resin composition to 180 DEG C or more, the resin composition can exhibit excellent thermal stability, so that the generation of monomers such as lactide or lactic acid and the formation of low molecular weight substances in the form of a ring oligomer . As a result, the molecular weight of the poly (lactic acid) resin is inhibited and the color change (yellowing) of the film is suppressed. As a result, not only excellent appearance but also greatly improved flexibility and excellent physical properties such as mechanical properties, heat resistance and blocking resistance It becomes possible to provide a packaging film to be displayed.

As a result, the poly (lactic acid) resin composition of the embodiment described above can exhibit excellent biodegradability and environmentally friendly characteristics peculiar to poly (lactic acid) resin while exhibiting excellent flexibility and the like with a minimum content of soft segment, . In particular, the resin composition of one embodiment and the polylactic acid resin contained therein, while solving the problem of low flexibility through the introduction of the soft segment, contains the resin component of biomass origin in a larger amount, . In addition, the poly (lactic acid) resin composition of one embodiment exhibits various physical properties such as excellent mechanical properties, stability and transparency, and is capable of providing packaging films and the like having suppressed yellowing and having good appearance.

Hereinafter, the poly (lactic 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 the resin composition, film, etc. containing the same will be described in detail.

In the polylactic acid resin composition of one embodiment described above, the polylactic acid resin has a content of ¹⁴ C isotopes in carbon atoms of about 7.2 x 10 ^-11 wt% to 1.2 x 10 ^-10 wt%, or about 9.6 x 10 ^-11 To about 1.2 x 10 ^-10 wt%, or about 1.08 x 10 ^-10 wt% to about 1.2 x 10 ^-10 wt%. Polylactic acid resin having such a content of ¹⁴ C isotopes can originate from more resins and carbon, or substantially all of resin and carbon, and can exhibit better biodegradability and environmentally friendly characteristics.

For this purpose, not only the polylactic acid repeating unit of the hard segment is derived from the biomass but also the polyether polyol repeating unit of the soft segment may be derived from the biomass. Such a polyether-based polyol repeating unit can be obtained, for example, from a polyether-based polyol resin derived from biomass. Such biomass can be any plant or animal resource, for example, a plant resource such as corn, sugarcane, or tapioca. The polyether polyol repeating unit derived from the biomass is derived from the biomass and the resin composition of one embodiment containing the polyether polyol thus obtained has 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 weight percent.

In the polylactic acid resin, the hard segment derived from the biomass has an organic carbon content (% C _bio ) of biomass origin defined by the above-mentioned formula 1 of at least about 90% by weight, for example, about 95 to 100 Wt%, and the soft segment derived from the biomass has an organic carbon content (% C _bio ) of biomass origin defined in the formula 1 of about 70 wt% or more, or about 75 to 95 wt% . In this soft segment, the urethane linkage connecting each polyether polyol repeat unit can be derived from a diisocyanate based compound derived from a fossil fuel.

The poly lactic acid resin contained in the resin composition of one embodiment described above has a high organic carbon content (% C _bio ) of about 60% by weight or more, or about 80% by weight or more based on the biomass, and is based on the standard ASTM D6866 , Which is the certification body of JBPA, to meet the criteria for obtaining the "Biomass Pla" certification. Thus, the polylactic acid resin can properly adhere to the " Biomass-based " label of JORA.

On the other hand, in the poly (lactic acid) resin described above, the poly (lactic acid) repeating unit represented by the formula (1) contained in the hard segment may refer to a poly (lactic acid) homopolymer or a repeating unit constituting the poly (lactic acid) homopolymer. Such polylactic acid repeating units can be obtained by a method for producing polylactic acid homopolymers well known to those skilled in the art. For example, L-lactide or D-lactide, which is a cyclic double monomer, is produced from L-lactic acid or D-lactic acid and ring-opening polymerization is carried out, or L-lactic acid or D- Among them, poly (lactic acid) repeating units having a higher polymerization degree can be obtained through ring-opening polymerization, which is preferable. 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.

The polyurethane polyol repeating unit contained in the soft segment of the poly (lactic acid) resin is a structure in which the polyether polyol repeating units of the above formula (2) are linearly connected via a urethane bond (-C (= O) -NH-) . More specifically, the polyether polyol repeating units refer to a polymer obtained by ring-opening (co) polymerization of a monomer such as an alkylene oxide, or a repeating unit constituting the same, and may have a hydroxyl group at the 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 linked to each other via the urethane bond, A polyurethane polyol repeating unit can be formed. 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. Such polyurethane polyol repeating units enable the provision of films exhibiting excellent physical properties without lowering the heat resistance, blocking resistance, mechanical properties or transparency of the poly (lactic acid) resin composition or films containing them.

On the other hand, there have been known polylactic acid copolymers and resin compositions or films containing the soft segments in which the polyester polyol repeating units are linked by urethane bonds. However, such a polylactic acid copolymer has a problem that the transparency of the film is lowered and the haze value is increased due to low compatibility of the polyester polyol and the polylactic acid. In addition, such a polylactic acid copolymer has a wide molecular weight distribution and a poor melt characteristic, and thus the film extruded state is not good, and the mechanical properties, heat resistance and blocking resistance of the film are also insufficient.

Then, a polylactic acid copolymer in which a polyether polyol repeating unit is copolymerized with a polylactic acid repeating unit in a branched form using a trifunctional or higher isocyanate compound, or a copolymer obtained by copolymerizing the above polyether polyol repeating unit and poly Polylactic-type copolymers in the form of chain-extended by a urethane reaction have also been previously known. However, these previously known poly (lactic acid) copolymers also have insufficient heat resistance, mechanical properties and blocking resistance due to the small block size of the poly (lactic acid) repeating units corresponding to the hard segments, And the film extrusion state is not good.

On the contrary, a polylactic acid resin in which a plurality of polyether polyol repeating units includes a polyurethane polyol repeating unit linearly connected through a urethane bond and a polylactic acid repeating unit, and a resin composition of one embodiment comprising the same, It is possible to provide a film exhibiting excellent flexibility by the unit while exhibiting a large molecular weight and a narrow molecular weight distribution and containing a polylactic acid repeating unit in a large segment size so that the film exhibits excellent mechanical properties, Let's do it. Therefore, it has been found that the poly (lactic acid) resin and the resin composition of one embodiment including the same can solve the problems of the previously known copolymers and provide a film having excellent physical properties and greatly improved flexibility.

The polyether polyol repeating unit and the diisocyanate compound are reacted so that the molar ratio of the isocyanate group of the compound of the terminal hydroxyl group: diisocyanate compound of the polyether polyol repeating units is from about 1: 0.50 to about 1: 0.99, Urethane polyol repeating units can be formed. Preferably, the reaction molar ratio of the isocyanate group of the terminal hydroxyl group: diisocyanate compound of the polyether polyol repeat units is from about 1: 0.60 to about 1: 0.95, more preferably from about 1: 0.70 to about 1: 0.90 .

As described in more detail below, the polyurethane polyol repeating unit refers to a polymer formed by linking the polyether polyol repeating units linearly through an urethane bond or a repeating unit constituting the polymer, wherein the polyether polyol repeating unit has a hydroxyl group have. Accordingly, the polyurethane polyol repeating unit can act as an initiator in the polymerization process for the formation of the polylactic acid repeating unit. However, if the molar ratio of the hydroxyl group to the isocyanate group is excessively high, the number of terminal hydroxyl groups of the polyurethane polyol repeating unit is insufficient (OHV <2), and the polyurethane polyol repeating unit may not function properly as an initiator. When the molar ratio of the hydroxyl group to the isocyanate group is too low, the number of terminal hydroxyl groups in the polyurethane polyol repeating unit becomes too large (OHV > 21), making it difficult to obtain polyanhydride repeating units and poly lactic acid resins having a high molecular weight.

On the other hand, the polyether polyol repeating unit may be, for example, a polyether polyol (co) polymer obtained by ring-opening (co) polymerization of at least one alkylene oxide or a repeating unit thereof. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran. Examples of the polyether polyol repeating unit obtained by the reaction 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 such a molecular weight of the polyether polyol repeating unit is excessively large or small, the flexibility and mechanical properties of the film obtained from the polylactic acid resin and the resin composition of one embodiment may become insufficient. In addition, since the polylactic acid resin may be difficult to meet appropriate molecular weight characteristics and the like, the processability of the resin composition may be lowered, or the flexibility or mechanical properties of the film may be deteriorated.

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, , 5-naphthalene diisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'- bisphenylenediisocyanate, hexamethylene di Isocyanate, isophorone diisocyanate, or hydrophenylmethane diisocyanate. In addition, various diisocyanate compounds well known to those skilled in the art can be used without limitation. However, it is preferable to use 1,6-hexamethylene diisocyanate in view of imparting flexibility to the poly (lactic acid) resin film.

On the other hand, the polylactic acid resin contained 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 bonded to 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]

Polyester repeating unit (L) -Ester-polyurethane polyol repeating unit (E-U-E-U-E) -Ester-

In the general formula (1), E represents a polyether polyol repeating unit, U represents a urethane bond, and Ester represents an ester bond.

The polyurethane polyol repeating unit and the polyurethane polyol repeating unit are combined so that the polyurethane polyol repeating unit or the like for imparting flexibility can be prevented from bleeding out. Transparency, mechanical properties, heat resistance, blocking resistance, and the like. The molecular weight distribution, glass transition temperature (Tg) and melting temperature (Tm) of the poly (lactic acid) repeating unit and polyurethane polyol repeating unit are optimized according to the block copolymer type The mechanical properties, flexibility and heat resistance of the film can be further improved.

However, it is not necessary that all of the polylactic acid repeating units contained in the polylactic acid resin and the resin composition are in the form of a block copolymer bonded with the polyurethane polyol repeating unit, and at least a part of the polylactic acid repeating units is the poly It may be in the form of a poly (lactic acid) homopolymer without being bonded to the urethane polyol repeating unit. In this case, the polylactic acid resin may be in the form of a mixture comprising the block copolymer described above and a polylactic acid repeating unit not bonded to the polyurethane polyol repeating unit, that is, a polylactic acid homopolymer.

On the other hand, based on 100 parts by weight of the total of the polylactic acid resin (100 parts by weight of the block copolymer described above and, when the polylactic acid homopolymer is optionally contained, 100 parts by weight of such a homopolymer) 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, about 5 to 35 parts by weight, or about 5 to 20 parts by weight, or about 8 to 18 parts by weight, Parts by weight.

If the content of the soft segment is excessively high, it may be difficult to provide a poly (lactic acid) resin having a high molecular weight and a resin composition containing the same, and the mechanical properties such as the strength of the film may be deteriorated. 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 other hand, if the content of the soft segment is too low, there is a limit to improve the flexibility of the poly (lactic acid) resin and the film thereof. Particularly, the glass transition temperature of the poly (lactic acid) resin is excessively high, so that the flexibility of the film may be deteriorated. In addition, since the polyurethane polyol repeating unit of the soft segment is difficult to act as an initiator, It may not be manufactured.

The poly (lactic acid) resin composition of one embodiment includes a specific amount of an antioxidant together with the poly (lactic acid) resin described above. Such an antioxidant may be contained in a specific amount as described above to suppress the yellowing of the polylactic acid resin, thereby improving the appearance of the resin composition and the film. In addition, the antioxidant can suppress oxidation or pyrolysis of a soft segment or the like.

As such an antioxidant, at least one of Hindered phenol antioxidant, amine antioxidant, thio antioxidant or phosphite antioxidant may be used, and various antioxidants known to be usable in other poly lactic acid resin compositions may be used .

 However, since the resin composition of the embodiment has polyether polyol repeating units, it tends to be easily oxidized or pyrolyzed during high temperature polymerization, high-temperature extrusion processing or molding. 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; Butyl-p-cresol, octadecyl-3- (4-hydroxy-3,5-di-t- butylphenyl) propionate, tetrabis [methylene- Butyl-4-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di- 4-hydroxybenzylphosphite diethyl ester, 4,4'-butylidene-bis (3-methyl-6-t-butylphenol), 4, Hindered phenol system such as 4'-thiobis (3-methyl-6-t-butylphenol) or bis [3,3-bis- (4'-hydroxy-3'- tert- butyl- Primary antioxidants; Amines such as phenyl-? -Naphthylamine, phenyl-? -Naphthylamine, N, N'-diphenyl-p-phenylenediamine or N, N'-di-? -Naphthyl- Secondary antioxidant; Thio such as dilauryl disulfide, dilauryl thiopropionate, distearyl thiopropionate, mercaptobenzothiazole, or tetramethyl thiuram disulfide tetrabis [methylene-3- (laurylthio) propionate] Secondary antioxidants are; (2,4-di-t-butylphenyl) pentaerythritol diphosphite or (1,1'-Biphenyl) -4,4'-Diylbisphosphonous acid tetrakis And a phosphite-based secondary antioxidant 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 described above, the antioxidant may be added in an amount of about 100 to 3000 ppmw, or about 100 to 2000 ppmw, or about 500 to 1500 ppmw, or about 1000 ppmw, based on the amount of monomer added for forming the polylactic acid repeating unit in the resin composition. To 1500 ppmw. When the content of the antioxidant is excessively low, the polylactic acid resin may be yellowed by oxidation or the like to the softening component such as the soft segment, and the appearance of the resin composition and the film may become poor. Also, when the content of the antioxidant is too high, the antioxidant may lower the polymerization rate of lactide and the like, so that the hard segment including the polylactic acid repeating unit may not be produced properly, and the mechanical properties of the polylactic acid resin Can be lowered.

In addition to the antioxidants mentioned above, the polylactic acid resin may contain various known plasticizers, ultraviolet stabilizers, coloring agents, matting agents, deodorants, flame retardants, lubricants, antistatic agents, release agents, antioxidants, ion exchange Pigments, pigments, inorganic pigments, organic particles, and the like.

Examples of the plasticizer include phthalate ester plasticizers such as diethyl phthalate, dioctyl phthalate and dicyclohexyl phthalate; Aliphatic dibasic acid ester plasticizers such as di-n-butyl adipate, di-n-octyl adipate, di-n-butyl sebacate and di-2-ethylhexyl azelate; Phosphate ester plasticizers such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate; Tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, tributyl citrate, and other hydroxycarboxylic acid ester plasticizers; Fatty acid ester-based plasticizers such as methyl acetyl ricinoleate and methyl stearate; Polyhydric alcohol ester plasticizers such as glycerin triacetate; Epoxidized soybean oil, epoxylated amami-oil fatty acid butyl ester, and epoxy-based stearyl epoxy stearate. Examples of the coloring pigment include inorganic pigments such as carbon black, titanium oxide, zinc oxide and iron oxide; Organic pigments such as cyanine pigments, phosphorus pigments, quinone pigments, lineron pigments, isoindolinone pigments, and thioindigo pigments. Inorganic or organic particles may be further added to improve the anti-blocking property of other films. Examples of the inorganic or organic particles include silica, colloidal silica, alumina, alumina sol, talc, mica, calcium carbonate, polystyrene, polymethylmethacrylate, And the like. 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. The poly (lactic 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.

The polylactic acid resin, for example, the block copolymer contained therein, has a molecular weight distribution (Mw / Mn) defined as a ratio of a number average molecular weight (Mn) to a weight average molecular weight (Mw) of about 1.60 to 2.20 May have a value of about 1.80 to 2.15. Since the poly (lactic acid) resin exhibits such a narrow molecular weight distribution, it exhibits an appropriate melt viscosity and melting property when it is melt processed by a method such as extrusion, and can exhibit excellent film extrusion state and processability. In addition, the film containing the poly (lactic acid) resin can exhibit excellent mechanical properties such as strength. On the other hand, when the molecular weight distribution is excessively narrowed (decreased), the melt viscosity at the processing temperature for extrusion and the like is excessively large, so that processing as a film may be difficult. Conversely, when the molecular weight distribution becomes too large Or the melt viscosity is too small, so that it is difficult to form the film into a film itself or the film extrusion state may be poor.

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, .

And, the polylactic acid resin, for example, the block copolymer contained therein, has a glass transition temperature (Tg) of about 8 to 55 캜, or about 25 to 55 캜, or about 30 to 55 캜. Since such a poly (lactic acid) resin exhibits such a glass transition temperature range, the flexibility and stiffness of the film containing the resin composition of one embodiment of the invention can be suitably maintained and suitably used as a packaging film. If the glass transition temperature of the poly (lactic acid) resin is excessively low, the flexibility of the film may be improved. However, as the stiffness becomes too low, the slipping, handling, Blocking property and the like may become poor, which may make the application to a packaging film inappropriate. On the other hand, if the glass transition temperature is too high, the flexibility of the film is low and the stiffness is too high, so that the film is easily folded and the mark does not disappear, or the adhesion to the product may be poor when wrapped. 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 one embodiment of the present invention may contain less than about 1% by weight of a monomer (for example, a lactide used for producing a polylactic acid repeating unit Monomer, etc.) may remain, and more preferably, only about 0.01 to 0.5% by weight of the monomer may remain. Since the resin composition contains a block copolymer having specific structural characteristics and a polylactic acid resin containing the block copolymer and a specific amount of an antioxidant, most of the lactide monomer used in the production process participates in the polymerization, And the depolymerization or decomposition of the polylactic acid resin does not substantially take place. For this reason, the poly (lactic acid) resin composition of one embodiment may contain a minimized amount of residual monomer, for example, residual lactide monomer and the like.

If the residual monomer content is about 1% by weight or more, problems arise during film processing using the resin composition, and the molecular weight of the poly (lactic acid) resin is decreased due to film processing, Even when applied to food packaging, residual monomers may bleed out and cause stability problems.

On the other hand, the poly (lactic acid) resin composition may have a color-b value of less than 6 and preferably not more than 5 in a chip state. The resin composition of this embodiment contains an optimized amount of an antioxidant, so that the yellowing of the poly (lactic acid) resin can be suppressed, so that the color-b value of less than 6 can be exhibited. If the color-b value of the resin composition is 6 or more, the appearance of the film may deteriorate when the film is developed for use in a film, which may lower the value of the product.

On the other hand, the above-mentioned poly (lactic acid) resin composition and the poly (lactic acid) resin contained therein may be prepared by ring-opening (co) polymerization of monomers such as alkylene oxide or the like to form a (co) polymer having polyether polyol repeating units; 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; (D or L-lactic acid) or ring-opening polymerization of lactide (D or L-lactide) in the presence of the above-mentioned (co) polymer having an antioxidant and a polyurethane polyol repeating unit . &Lt; / RTI &gt; Wherein the lactic acid or lactide and the polylactic acid repeat unit formed therefrom may originate from a biomass and suitably the alkylene oxide and the polyether polyol repeat unit formed therefrom may also be of biomass origin have.

According to such a production method, a poly (lactic acid) resin in which the poly (lactic acid) repeating unit of Formula 1 is included as a hard segment and a predetermined polyurethane polyol repeating unit is contained as a soft segment can be produced. In addition, as the antioxidant is used in the production of the polylactic acid repeat unit, the polylactic acid resin composition of one embodiment comprising the polylactic acid resin and the antioxidant can be produced.

More specifically, in the above production process, the polyether polyol (co) polymer having the repeating unit of the formula (2) causes a urethane reaction with the diisocyanate compound, and a large number of the repeating units of the formula (2) are linearly connected via a urethane bond (Co) polymers having polyurethane polyol repeating units can be formed. In addition, hydroxyl groups at the ends of the polymer act as an initiator, and the lactic acid is subjected to condensation polymerization or lactide ring-opening polymerization. As a result, the polylactic acid repeating unit is formed, and the polylactic acid repeating unit and the polyurethane polyol repeating unit are formed into hard segments and Polylactic acid resin which is contained as a soft segment can be produced. Furthermore, when the lactide or the like is polymerized to form a polylactic acid repeating unit, the resin composition of one embodiment comprising the yellowing-inhibited polylactic acid resin and the antioxidant may be prepared together with a specific amount of the antioxidant . 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 it is possible to provide a film whose yellowing is suppressed and whose appearance is also good.

Also, the polylactic acid resin produced by the above-mentioned method has a hard segment and optionally a soft segment originating from biomass, wherein the organic carbon content (% C _bio ) of the biomass origin as defined by Formula 1 is about 60 wt% Or more.

In the case of introducing a polyester-based polyol repeating unit other than the polyether-based polyol repeating unit or by chain-extending after polyether-based polyol is first polymerized with lactic acid or the like in a different reaction sequence, It is difficult to produce a block copolymer having excellent properties and a polylactic acid resin containing the block copolymer. Further, in this case, in order to achieve excellent flexibility, it is necessary to introduce another resin such as a polyester polyol repeating unit having a higher content of fossil fuels origin, so that the above-mentioned organic carbon content (% C _bio ) Can be difficult to achieve.

The amount of the (co) polymer having a polyurethane polyol repeating unit corresponding to the molecular weight of the whole poly (lactic acid) resin, the molecular weight of the polyether polyol (co) polymer or the content of the soft segment, It becomes a main factor that makes polylactic acid resin having one excellent physical property to be produced. However, the appropriate range of the molecular weight of the polylactic acid resin or the content of the soft segment has already been described above, and thus a further detailed description thereof will be omitted.

Hereinafter, the method for producing such a poly (lactic acid) resin composition will be described in more detail.

First, a monomer such as at least one alkylene oxide is ring-opened (co) polymerized to form a (co) polymer having a polyether polyol repeat unit. This is a method for producing a polyether polyol 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 in which polyether polyol repeating units have polyurethane polyol repeating units in a linearly linked form via the urethane bond can be formed, which is included as a soft segment of the above-mentioned polylactic acid resin. At this time, the polyurethane polyol (co) polymer is formed in such a manner that the polyether polyol repeating units (E) are linearly bonded in the form of EUEUE through a urethane bond (U) to have polyether polyol repeating units at both terminals .

At this time, the alkylene oxide and the polyether polyol repeating units obtained therefrom may originate from biomass such as plant resources, and thus the polyurethane polyol (co) polymer has an organic carbon content (%) of biomass origin, C _bio ) is about 70% by weight or more and can be considerably high.

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

Then, lactic acid (D or L-lactic acid) is condensation-polymerized in the presence of the (co) polymer having the polyurethane polyol repeating unit and a specific content of antioxidant, or lactide (D or L- , A polylactic acid resin composition of one embodiment including the above-mentioned block copolymer (or a polylactic acid resin including the same) and a predetermined amount of an antioxidant can be produced. That is, when such a polymerization reaction is carried out, the yellowing due to the oxidation of the soft segment and the like is suppressed by the antioxidant, and the polylactic acid repeating unit contained in the hard segment is formed to produce the polylactic acid resin, The polyurethane polyol repeating unit may be bonded to the terminal of the repeating unit of lactic acid to form a block copolymer.

As a result, a known polylactic acid copolymer prepared by preparing a prepolymer in which a polyether polyol and a poly (lactic acid) are bonded to each other and then lengthening the prepolymers with a diisocyanate compound, or a polyol compound obtained by linking the prepolymers with a trifunctional or higher isocyanate compound And a resin composition containing the block copolymer may be formed. The block copolymer may have a structure different from that of the known branched copolymer. Particularly, since the block copolymer may contain a block (hard segment) in which the polylactic acid repeating units are bonded to each other in a relatively large unit (molecular weight), the film formed of the poly (lactic acid) resin containing the block copolymer has a narrow molecular weight distribution, Thereby exhibiting excellent mechanical properties and heat resistance. On the other hand, the above-mentioned known copolymers have a structure in which the poly (lactic acid) repeating units having small units (molecular weight) are alternately arranged randomly with the polyether polyol repeating units and the like, and thus the film obtained therefrom has the above- And the mechanical properties and heat resistance are not sufficient. Furthermore, since the block copolymer can be produced while suppressing the yellowing by the antioxidant during its polymerization, the resin composition and the film containing it can also exhibit excellent appearance.

Meanwhile, the lactide ring-opening polymerization reaction may be carried out 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 can be in the form of carboxylates, alkoxides, halides, oxides or carbonates of these metals. Preferably, as the metal catalyst, tin octylate, titanium tetraisopropoxide or aluminum triisopropoxide may be used.

In addition, the polylactic acid repeating unit forming step such as the lactide ring-opening polymerization reaction may be continuously carried out in the same reactor in which the urethane reaction has proceeded. That is, a polyether polyol polymer and a diisocyanate compound are subjected to a urethane reaction to form a polymer having a polyurethane polyol repeating unit, and then a monomer such as lactide and a catalyst, etc., are continuously added to this reactor to form a poly have. As a result, the polylactic acid repeating unit and the polylactic acid resin containing the polylactic acid repeating unit can be continuously produced with high yield and high productivity, while the polymer having the polyurethane polyol repeating unit functions as an initiator.

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.

Further, since the poly (lactic acid) resin is produced so as to have a predetermined glass transition temperature and optionally a predetermined melting temperature, a film or the like obtained therefrom can exhibit optimized flexibility and stiffness as a packing material, And the blocking resistance and the heat resistance are further improved. Accordingly, such a poly (lactic acid) resin and a resin composition of one embodiment including the poly (lactic acid) resin can be very suitably applied to a packaging material such as a film. In addition, it is already described that the poly (lactic acid) resin has a relatively high organic carbon content (% C _bio ) from the _biomass , and thus can exhibit excellent biodegradability and environmentally friendly characteristics.

The polylactic acid resin is included together with a specific amount of an antioxidant so that the yellowing during production or use can be suppressed and the resin composition containing these components can exhibit excellent appearance and merchandise, Mechanical properties and other physical properties.

According to another embodiment of the present invention, there is provided a packaging film comprising the above-described poly (lactic acid) resin composition. Such a packaging film is excellent in mechanical properties, heat resistance, blocking resistance, transparency and processability, and can exhibit optimized flexibility and stiffness as well as a good appearance without yellowing And can exhibit environmentally friendly properties, and thus can be used as packaging materials in various fields.

Such a packaging film may have various thicknesses depending on each use, and may have a thickness of about 5 to 500 mu m. For example, when used as a wrapping film such as a wrap film or an envelope, a thickness of about 5 to 100 mu m in terms of flexibility, handleability, and strength, preferably a thickness of about 7 to 50 mu m, Lt; RTI ID = 0.0 &gt; um. &Lt; / RTI &gt;

The packaging film was subjected to a tensile test under the conditions of a temperature of 20 ° C and a relative humidity of 65% using an Instron 1123 UTM universal testing machine at a stretching speed of 300 mm / min and a distance between grips of 100 mm and a width of 10 mm and a length of 150 mm 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, and more preferably about 500 to 600 kgf / mm 2 . Such a range of the Young's modulus sum may reflect the optimized flexibility and stiffness of the packaging film, and such flexibility and stiffness appear to be due to the fact that the poly (lactic acid) resin meets the above-mentioned structural characteristics and glass transition temperature.

However, when the Young's modulus total is too low, spreading or loosening occurs in the film-forming and processing steps of the film, and handleability, process permeability, slit processability or shape-retaining property may become 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 film for packaging is subjected to a tensile test under the same conditions as the above-mentioned Young's modulus, an initial tensile strength of at least about 10 kgf / mm 2, preferably an initial tensile strength of at least about 12 kgf / mm 2, Lt; RTI ID = 0.0 &gt; kgf / mm2 &lt; / RTI &gt; 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.

The packing film may have a weight change rate of about 3 wt% or less, preferably about 0.01 to 3.0 wt%, more preferably about 0.05 to 1.0 wt% when treated in a hot air oven at 100 캜 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 the plasticizer, the residual monomer, the additive, etc. are bleed out, and these components can 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, About 1% or less, and a transmittance of 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 packaging film described above may be provided with properties required for a food packaging material such as heat sealing property, gas barrier property such as water vapor, oxygen or carbonic acid gas, releasing property, printing property, etc. . 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, an inflation method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, or the like may be applied to the above-mentioned poly (lactic acid) resin to form a stretched film and then to fix it. At this time, in the stretched film forming process, the polylactic acid resin is melt-extruded by a sheet-form extruder equipped with a T-die, and the sheet-like melt extrudate is cooled and solidified to obtain an unstretched film. Direction and the 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 terms of the strength and flexibility of the final packaging film, it is preferable that the stretching temperature is controlled to be not lower than the glass transition temperature of the polylactic acid resin and below the crystallization temperature. 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 environment-friendly characteristics and biodegradability peculiar to polylactic acid resin. Therefore, such packaging films can be suitably applied as packaging materials in various fields. For example, sanitary films, lamination films, shrinkable labels, and matte films for snack packaging, such as consumer packaged goods or grocery packages, envelopes, refrigerated / frozen food packaging, shrinkable over-wrapping films, Bundle bundle films, sanitary napkins or baby products In addition, it can be widely used as packing material for industrial materials such as agricultural multi-film, automobile paint film protective sheet, garbage bag and compost bag.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a polylactic acid resin which exhibits environmentally-friendly characteristics and biodegradability peculiar to polylactic acid resin, exhibits optimized flexibility and stiffness, excellent mechanical properties, heat resistance, transparency, blocking resistance, And packaging films may be provided. Accordingly, such a poly (lactic acid) resin and a packaging film can be suitably applied as packaging materials in various fields, thereby being able to replace the packaging film obtained from the crude oil-based resin and contributing greatly to prevention of 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.

* Property Definition and Measurement Method: Definition and measurement method of each property in the following embodiments are as summarized below.

(1) NCO / OH: terminal hydroxyl group of an isocyanate group of a diisocyanate compound (for example, hexamethylene diisocyanate) / polyether polyol repeating unit (or (co) polymer) for formation of polyurethane polyol repeating unit &Quot;

(2) OHV (KOH mg / g): The polyurethane polyol repeating unit (or (co) polymer) was dissolved in dichloromethane and acetylated, and acetic acid produced by hydrolysis thereof was titrated with 0.1N 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) and molecular weight distribution (Mw / Mn): The poly lactic acid resin was dissolved in Chloroform at a concentration of 0.25% by weight and subjected to Gel permeation chromatography (Viscotek TDA 305, Column: Shodex LF804 * 2ea), and weight average molecular weight (Mw) and number average molecular weight (Mn) were calculated as polystyrene as a standard material. Molecular weight distribution values were calculated from the 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 value of the tangent line and the baseline near the endothermic curve was defined as Tg.

(5) Tm (melting temperature, 占 폚): Using a differential scanning calorimeter (manufactured by TA Instruments), the sample was subjected to melt quenching and then heated to 10 占 폚 / min. The maximum value of the melting endothermic peak of the crystal was defined as Tm.

(8) Residual monomer (lactide) content (wt%): 0.1 g of the resin was dissolved in 4 ml of chloroform, and 10 ml of hexane was added thereto for filtering and analyzed by GC analysis.

(7) Content (wt%) of polyurethane polyol repeating units: The content of the polyurethane polyol repeating units contained in each produced poly (lactic acid) resin was quantified using a 600 MHz nuclear magnetic resonance (NMR) spectrometer.

(8) chip color-b: resin Chip resin was measured by using a chroma meter CR-410 manufactured by Konica Minolta Sensing Co., Ltd.

(9) Extrusion State and Melt Viscosity: The poly (lactic acid) resin was extruded from a single screw extruder having a diameter of 30 mm equipped with a T die for producing an unstretched sheet into a sheet at an extrusion temperature of 200 to 250 DEG C, A drum was electrostatically cast on the drum. At this time, the melt viscosity of the discharged material on the sheet was measured using a Physica Rheometer manufactured by Physica, USA. Specifically, through the use of a 25 mm parallel plate type shear force applying device, the complex viscosity (Pa · s) of the molten resin at the shear rate (1 / s) = 1 while maintaining the initial temperature of the discharged material s) was measured with the above-mentioned Physica Rheometer, and the state of melt viscosity (extrusion state) was evaluated according to the following criteria.

⊚: Good melt spinning speed and good winding on a cooling drum. ◯: Melt viscosity is slightly low, but winding is possible. ◯: Winding is not possible due to too low melt viscosity.

(10) Initial tensile strength (kgf / mm 2) MD, TD: A film sample having a length of 150 mm and a width of 10 mm was aged for 24 hours in an atmosphere at a temperature of 20 ° C and a humidity of 65% RH for 24 hours. ) Using a universal testing machine, tensile strength was measured at a stretching speed of 300 mm / min and a distance between grips of 100 mm. The averages of the 5 tests in total were expressed as the results. 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 / mm &lt; 2 &gt;) MD, TD: The same specimen as the tensile test described in (6) above was subjected to a stretching speed of 300 mm / min using a UTM (INSTRON) universal testing machine according to ASTM D638, Young's modulus was measured. The averages of the 5 tests in total were expressed as the results. 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 (horizontal line) occurred

○: Less than 3 wave patterns (horizontal lines) occur

×: More than 5 wave patterns (horizontal lines)

(16) Weight change rate (%) at 100 캜: The film sample was previously aged for 24 hours in an atmosphere of a temperature of 23 캜 and a humidity of 65% RH, 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: The surface of the film sample after the heat treatment of the above (12) was observed to determine the occurrence of pinhole. Further, the extent to which the low molecular weight plasticizer component was bleed out to the film surface due to tactile sensation was evaluated according to the following criteria in an A4 size film sample.

◎: No occurrence of pin hole and bleed out

○: Pin hole is less than 5 or bleed out occurs but not severe

×: More than 5 pin holes or bleed out occur

(18) Haze (%) and Transmittance (%): The film sample was previously aged in an atmosphere at a temperature of 23 DEG C and a humidity of 65% RH for 24 hours, and then, using a haze meter (Model: NDH2000, Japan) according to JIS K7136 And the average value was calculated as a result.

(19) Blocking resistance: Using a COLORIT P type (manufactured by Coulter Co.) of a stamping foil, the antistatic side and the printing side of the film sample were matched and allowed to stand at a temperature of 40 캜 and a pressure of 1 kg / cm 2 for 24 hours, The blocking state of the antistatic layer and the printing surface was observed. Based on the observation results, the anti-blocking property between the antistatic layer (layer A) and the printed surface of the in-mold transfer film was evaluated on the basis of the following criteria. At this time, the practical performance is satisfied up to.

◎: No change

○: slight surface change (less than 5%)

X: over 5% exfoliation

(20) Yellow coloration degree of film: The film sample was pulverized with a crusher, followed by dehumidification drying and crystallization at 120 ° C., and then melted at about 200 ° C. by a small single screw extruder (Haake Company, Rheomics 600 extruder) . The difference in color-b value of the chips before and after the film processing was measured, and the yellow coloring degree was evaluated according to the following criteria.

?: Almost no yellowing at 2 or less,

?: Slightly yellowing at 5 or less,

×: Excessive yellowing occurred in excess of 5.

(21) Organic carbon content of biomass origin (% C _bio ): The content of organic carbon originating from biomass is measured from the biomass source content test by the radioactive carbon concentration (Percent Modern; C14) according to ASTM D6866 Respectively.

The raw materials used in the following Examples and Comparative Examples are as follows:

1. A polyether polyol repeating unit (or (co) polymer) or a corresponding substance

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

            Organic carbon-based polyols of biomass origin

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

            Organic carbon-based polyols 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

             Organic carbon-based polyols of biomass origin

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

- PBSA 11.0: aliphatic polyester polyols made from 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 monomers

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

 Monomers consisting only of organic carbon of biomass origin

4. Antioxidants, etc.

- TNPP: Tris (nonylphenyl) phosphite

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

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

- PEPQ: (1,1'-Biphenyl) -4,4'-Dlybisphosphonous 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. Preparation of polylactic acid resins A to F

Components and contents of reactants as shown in the following Table 1 were charged together with the catalyst in an 8 L reactor equipped with a nitrogen gas introduction pipe, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system. As a catalyst, 130 ppmw of Dibutyltin dilaurate was used as a total reactant. The urethane reaction was carried out under a nitrogen stream at 70 ° C for 2 hours, and 4 kg of L- (or D-) lactide was added thereto, followed by nitrogen flushing five times.

Then, the temperature was raised to 150 ° C to completely dissolve the L- (or D-) lactide, and 120 ppmw of the catalyst Tin 2-ethylhexylate was diluted with 500 ml of toluene to the total reactant content through the catalyst inlet. The reaction was carried out at 185 ° C under a nitrogen pressure of 1 kg for 2 hours, 200 ppmw of phosphoric acid was added to the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. The unreacted L- (or D-) lactide (about 5 wt.% Of the initial charge) was then removed through a vacuum reaction until 0.5 torr was reached. The molecular weight characteristics, Tg, Tm,% C _bio, etc. of the obtained resin were measured and shown in Table 1.

B. Preparation of polylactic acid resin L

A polyol and 4 kg of L-lactide as shown in Table 1 were charged into an 8 L reactor equipped with a nitrogen gas introduction pipe, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system and subjected to nitrogen flushing five times. The temperature was raised to 150 ° C to completely dissolve the L-lactide, and 120 ppmw of the catalyst Tin 2-ethylhexylate was diluted with 500 ml of toluene through the catalyst inlet and added to the reaction vessel. Subsequently, the reaction was carried out at 185 DEG C under a pressure of 1 kg of nitrogen for 2 hours, 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 reaction until 0.5 torr was reached. The molecular weight characteristics, Tg, Tm,% C _bio, etc. of the obtained resin were measured and shown in Table 1.

C. Preparation of polylactic acid resin M

6 g of 1-Dodecanol and 4 kg of L-lactide as shown in the following Table 1 were fed into an 8 L reactor equipped with a nitrogen gas introduction pipe, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system and subjected to nitrogen flushing five times . The temperature was raised to 150 ° C to completely dissolve the L-lactide, and 120 ppmw of the catalyst Tin 2-ethylhexylate was diluted with 500 ml of toluene through the catalyst inlet and added to the reaction vessel. Subsequently, the reaction was carried out at 185 DEG C under a pressure of 1 kg of nitrogen for 2 hours, 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 reaction until 0.5 torr was reached. The molecular weight characteristics, Tg, Tm,% C _bio, etc. of the obtained resin were measured and shown in Table 1.

D. Preparation of poly (lactic acid) resin O

A PBSA polyol (polyester polyol) and HDI as shown in Table 1 were charged into an 8 L reactor equipped with a nitrogen gas introduction pipe, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system, and nitrogen flushing was performed five times. As a catalyst, 130 ppmw of Dibutyltin dilaurate was used as a total reactant. The urethane reaction was carried out at 190 占 폚 for 2 hours in a nitrogen stream, 4 kg of L-lactide was added, L-lactide was completely dissolved at 190 占 폚 in a nitrogen atmosphere, 120 ppmw of the addition polymerization catalyst Tin 2-ethylhexylate and 1000 ppmw of Dibutyltin dilaurate as an ester and / or ester amide exchange catalyst were diluted with 500 ml of toluene and added to the reaction vessel. The reaction was carried out at 190 DEG C under 1 kg of nitrogen pressure for 2 hours, 200 ppmw of phosphoric acid was added at the catalyst inlet and mixed for 15 minutes to inactivate the residual catalyst. Unreacted L-lactide (about 5 wt. Of the initial charge) was then removed through a vacuum reaction until 0.5 torr was reached. The molecular weight characteristics, Tg, Tm,% C _bio, etc. of the obtained resin were measured and shown in Table 1.

E. Preparation of polylactic acid resin P

PEG, 3.6 kg of L-lactide and 0.4 kg of D-lactide as shown in the following Table 1 were fed into an 8 L reactor equipped with a nitrogen gas introduction pipe, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system, Nitrogen flushing was performed. The temperature was raised to 150 ° C to completely dissolve the lactide, and 120 ppmw of the catalyst Tin 2-ethylhexylate was diluted with 500 ml of toluene through the catalyst inlet and added to the reaction vessel. Subsequently, the reaction was carried out at 185 DEG C under a pressure of 1 kg of nitrogen for 2 hours, 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 wt.% Of initial charge) was removed through a vacuum reaction until 0.5 torr was reached. After that, 120 ppmw of dibutyltin dilaurate of 130 ppmw of the catalyst and HDI as shown in Table 1 below was diluted with 500 ml of toluene through a catalyst inlet and added to the reaction vessel. The reaction was carried out in a nitrogen atmosphere at 190 DEG C for 1 hour, and the molecular weight characteristics, Tg, Tm and% C _bio, etc. of the obtained resin were measured and are shown in Table 1.

F. Preparation of polylactic acid resin Q

PEG, 3.6 kg of L-lactide and 0.4 kg of D-lactide as shown in the following Table 1 were fed into an 8 L reactor equipped with a nitrogen gas introduction pipe, a stirrer, a catalyst inlet, an outlet condenser and a vacuum system, Nitrogen flushing was performed. The temperature was raised to 150 ° C to completely dissolve the lactide, and 120 ppmw of the catalyst Tin 2-ethylhexylate was diluted with 500 ml of toluene through the catalyst inlet and added to the reaction vessel. Subsequently, the reaction was carried out at 185 DEG C under a pressure of 1 kg of nitrogen for 2 hours, 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 wt.% Of initial charge) was removed through a vacuum reaction until 0.5 torr was reached. Then, 120 ppmw of D-L75 and 130 ppm of Dibutyltin dilaurate as shown in Table 1 below were diluted with 500 ml of toluene through a catalyst inlet and added to the reaction vessel. The reaction was carried out in a nitrogen atmosphere at 190 DEG C for 1 hour, and the molecular weight characteristics, Tg, Tm and% C _bio, etc. of the obtained resin were measured and are shown in Table 1.

G. Production of Film Examples 1 to 5, Comparative Examples 1 and 5 to 7

The polylactic acid resins prepared from A to E, M and O to Q were dried under reduced pressure at 80 ° C for 6 hours under a vacuum of 1 torr and then subjected to extrusion as shown in Table 2 in a 30 mm diameter single screw extruder equipped with a T die And extruded onto a sheet under a temperature condition. An unstretched film was produced by electrostatic casting or casting on a drum cooled to 5 ° C. This unstretched film was stretched three times in the longitudinal direction between the heating rolls under the stretching conditions shown in Table 2, and then the film stretched in the longitudinal direction was fixed with a clip, drawn into the tenter and stretched four times in the transverse direction, Heat treatment was performed at 120 캜 for 60 seconds. As a result, a biaxially stretched poly (lactic acid) resin film having a thickness of 20 mu m was obtained. The evaluation results of the obtained film are shown together in Table 2

H. Film Production of Example 6 and Comparative Examples 2 to 4

The resin mixture or polyol shown in Table 2 was dried under reduced pressure at 80 DEG C for 6 hours under a vacuum of 1 torr and then melted and kneaded at 190 DEG C in a biaxial kneading extruder to obtain a composition obtained by chipping. The composition was dried under reduced pressure at 80 DEG C for 6 hours under a vacuum of 1 torr, and then a biaxially oriented poly (lactic acid) resin film having a thickness of 20 mu m was prepared in the same manner as in the above method G. The evaluation results are also shown in Table 2.

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 (KOH mg / 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 repeating 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% 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, 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 in such a manner that NCO / OHV is 1 to 1 , And 6-hexametylene diisocyanate to obtain a polyurethane polyol repeating unit (or (co) polymer) in which polyether polyol repeating units such as poly (1,3-propanediol) are linearly linked, And corresponds to a polylactic acid resin (block copolymer) obtained by using. These polylactic acid resins were polymerized after mixing with a specific amount of antioxidant, and showed a low color b value and a low residual lactide content by suppressing yellowing. And, this polylactic acid resin was confirmed to contain% C _bio in an amount of about 60% by weight or more, using a monomer containing organic carbon of biomass origin determined according to standard ASTM D6866.

In the poly (lactic acid) resin, the polyurethane polyol repeating unit (or (co) polymer) has a value of OHV of 2 to 20, and may preferably serve as an initiator in the polymerization process for the formation of the poly . 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 占 폚 and a Tm of 155 to 178 占 폚. It was confirmed that the film was suitable for melt viscosity. In addition, the residual lactide content in the resin was not only lower than 1 wt%, but also had a color b value of less than 6, indicating that yellowing was hardly observed.

On the other hand, Resin L was an attempt to produce a poly (lactic acid) resin by using polyethylene glycol having a molecular weight of 8,000 as an initiator in the ring-opening polymerization of L-lactide immediately without a urethane reaction. However, in such a case, the OHV of the initiator was high, so that a poly (lactic acid) resin having a desired weight average molecular weight could not be obtained. In addition, it was confirmed that the resin L was not added with an antioxidant and had a very high residual lactide content and a low polymerization conversion. When the film extrusion temperature was 200 ° C or higher, the melt viscosity was too low to produce a film alone. In addition, Resin L was found to have a% C _bio content of less than 60 wt%.

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 case of poly (lactic acid) resin, it was possible to produce film alone at a film extrusion temperature of 200 ° C or higher. However, it was confirmed that the polylactic acid resin had a broad molecular weight distribution of 2.30.

The resin O is not a polyether polyol repeating unit but a polyurethane formed from a polyester polyol repeating unit such as PBSA as a softening component in the resin, while using a ring opening polymerization catalyst and an ester exchange catalyst and / or an ester amide exchange catalyst In the presence of at least one of a polyurethane and a 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. It was confirmed that the resin O had a remarkably wide molecular weight distribution of 2.85 and a relatively low Tm. In addition, it was confirmed that the resin O also had a relatively high residual lactide content and an extremely high color b value because no antioxidant was added.

Finally, the resins P and Q are prepared by firstly adding a lactide to a polyether polyol repeating unit, preparing a prepolymer in which the polyether polyol repeating unit and the poly (lactic acid) repeating unit are copolymerized, then chain-extending the prepolymer with a diisocyanate compound (Resin P) and a branched copolymer (resin Q) obtained by reacting the above prepolymers with an isocyanate compound having three or more functions. These resins P and Q were found to have a broad molecular weight distribution of 2.50 and 3.91 and a relatively low Tm. Further, the resin O was not added with an antioxidant, so that the residual lactide content was relatively high and the color b value was found to be 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 (캜) 220 230 240 200 200 230 240 200 200 200 200 200 240 Melting point (Pa · s) 1100 1600 2100 580 1000 1400 2000 250 1200 1400 1400 1200 1800 Extrusion state ◎ ◎ ◎ ○ ◎ ◎ ◎ X ◎ ○ ◎ X X Stretching temperature (占 폚) 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 Sum (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 / mm &lt; 2 &gt;) MD 5.3 8 10 5 4.8 9.0 9.8 1.5 8.7 7.9 5 6 11 F5 (kgf / mm &lt; 2 &gt;) TD 8.1 10 11 7.7 7.8 11.8 12 2.1 11 9.8 6.5 6.8 13 F100 (kgf / mm &lt; 2 &gt;) 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 / mm &lt; 2 &gt;) MD 236 230 330 212 180 190 386 179 338 327 150 160 302 Young's modulus (kgf / mm &lt; 2 &gt;) 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 show that the content of the softening component (polyurethane polyol repeating unit) in the poly (lactic acid) resin is 5 to 35 wt%, the color b value is low, , A weight average molecular weight of 100,000 to 400,000, a molecular weight distribution of 1.80 to 2.15 and a Tm of 155 to 178 ° C. Example 6 was also produced by using a composition comprising a mixture of a polylactic acid resin (resin F) and a general polylactic acid resin (resin M) belonging to the scope of the present invention and an antioxidant. The films of Examples 1 to 6 It has been confirmed that not only excellent mechanical properties such as an initial tensile strength of not less than 10 kgf / mm 2 in both the length and width directions, but also excellent flexibility as the total Young's modulus in the length and width directions is less than 750 kgf / mm 2. In addition, it was confirmed that the total Young's modulus was not too low, and the appropriate range was maintained, indicating that the stiffness was also at an appropriate level. Haze, blocking resistance and transparency, such as a weight change rate of 3 wt% or less when treated in a hot air oven at 100 캜 for 1 hour, a haze of 3% or less and a transmittance of 85% Heat resistance and other physical properties. In addition, the films of Examples 1 to 6 were good in appearance and excellent in thermal stability, so that the color b value change (yellowing degree) was not severe even after the film extrusion process.

On the other hand, the film of Comparative Example 1 made of a general poly (lactic acid resin) M has a Young's modulus of more than 750 kgf / mm &lt; 2 &gt; In addition, in the case of the film of Comparative Example 2 produced by using the resin M and the resin L together, the difference in melting point between the two resins was too large to be in an extruded state, and a wave pattern was generated in the final film . Furthermore, due to the high residual latent migration, pin holes were formed on the film, resulting in poor appearance of the film, problems such as blocking resistance, initial tensile strength, transmittance and yellowing resistance were also poor.

In Comparative Examples 3 and 4, poly (3, 3-propanediol) having a number average molecular weight of 2,400 and poly (1,3-propanediol) having a number average molecular weight of 11,000 were used as the plasticizer component -Butanediol and an aliphatic polyester polyol made of a condensate of succinic acid and adipic acid is simply mixed with resin M to form 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, the haze of the film was high, the degree of discoloration of yellow color was poor, and the plasticizer component bleed-out from the film surface 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 a film exhibited comparatively excellent flexibility due to the introduction of the polyurethane as a softening component at a small segment size at a random rate. However, since the polylactic acid repeating unit is also introduced into a relatively small segment size, the film exhibits poor heat resistance due to low Tm, The difficulty in filming was confirmed as a problem. Further, it has been confirmed that the haze value of the film is high and low transparency due to the low miscibility of the polyester polyol and poly (lactic acid) used for the formation of the softening component, and it is confirmed by the ester and / It was found that the distribution was widened and the melting characteristics were uneven, resulting in poor film extrusion state and mechanical property deterioration.

The films of Comparative Examples 6 and 7 contain a resin obtained by urethane reaction of a prepolymer obtained by addition polymerization of a lactide to a polyether polyol with a diisocyanate or an isocyanate compound having three or more functional groups. Such a resin also has a broad molecular weight distribution and a polyether polyol repeat The units are linearly connected to the urethane bond, and in addition, the structural characteristics of the present invention containing the relatively high molecular weight poly (lactic acid) repeating units as hard segments are not satisfied. These films were found to exhibit uneven melt viscosity and poor mechanical properties. In addition, it was confirmed that the blocking characteristics of the hard segment and the soft segment in the resin were lowered, exhibiting low heat resistance due to low Tm, and difficult to form a film due to a blocking problem.

In addition, due to the high residual lactide content and the relatively high color b value, the films of Comparative Examples 5 to 7 exhibited considerable appearance defects even in the film state, and the 100 DEG C weight change rate and the like, which are unsuitable for commercial application, were observed. In addition, since the films of Comparative Examples 5 to 7 are required to use an excessive amount of catalyst during the production of the resin, it is considered 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 due to increased production rate or weight change ratio at high temperature.

Claims (15)

A hard segment including a polylactic acid repeat unit represented by the following formula (1)
Wherein the polyether polyol repeating units represented by the following formula (2) are linearly connected through a urethane bond,
(% C _bio ) of the biomass origin defined by the following formula 1 is 80 wt% or more, and the content of the ¹⁴ C isotope in the carbon atoms is 9.6 X ^{10 -11} wt% to 1.2 X ^{10 -10} wt% Polylactic acid resin; And
An antioxidant in an amount of 1000 to 2400 ppmw based on the amount of the monomer added for forming the polylactic acid repeating unit,
Wherein the soft segment has an organic carbon content (% C _bio ) of biomass origin defined by the following formula 1: 70 wt% or more:
[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 poly (lactic acid) resin composition according to claim 1, wherein the poly (lactic acid) resin has a number average molecular weight of 50,000 to 200,000 and a weight average molecular weight of 100,000 to 400,000.
The poly (lactic acid) resin composition according to claim 1, wherein the poly (lactic acid) resin has a glass transition temperature (Tg) of 8 to 55 캜 and a melting temperature (Tm) of 155 to 178 캜.
The poly (lactic acid) resin composition according to claim 1, wherein the polyether polyol repeating units are linearly connected to each other through a urethane bond formed by a reaction between a hydroxyl group at the terminal and a diisocyanate compound to form a polyurethane polyol repeating unit.
5. The poly (lactic acid) resin composition according to claim 4, wherein the poly (lactic acid) resin comprises a block copolymer in which the terminal carboxyl group of the poly (lactic acid) repeating unit contained in the hard segment is ester-bonded to the terminal hydroxy group of the polyurethane polyol repeating unit.
6. The polylactic acid resin composition according to claim 5, wherein the polylactic acid resin comprises the block copolymer; And a polylactic acid repeating unit not bonded to the polyurethane polyol repeating unit.
The poly (lactic acid) resin composition according to claim 1, wherein the polyether polyol repeating unit has a number average molecular weight of 450 to 9000.
5. The poly (lactic acid) resin composition according to claim 4, wherein the reaction molar ratio of the isocyanate group of the terminal hydroxyl group: diisocyanate compound of the polyether polyol repeating units is 1: 0.50 to 1: 0.99.
The poly (lactic acid) resin composition according to claim 1, wherein the poly (lactic acid) resin comprises 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 thereof.
The poly (lactic acid) resin composition according to claim 1, which exhibits a color-b value of less than 6.
The poly (lactic acid) resin composition according to claim 1, wherein less than 1% by weight of the monomer remains relative to the weight of the poly (lactic acid) resin.
The poly (lactic acid) resin composition according to claim 1, wherein the antioxidant comprises at least one antioxidant selected from the group consisting of a hindered phenol antioxidant, a amine antioxidant, a thio antioxidant and a phosphite antioxidant.
A packaging film comprising the polylactic acid resin composition of claim 1.
14. The packaging film according to claim 13, having a thickness of 5 to 500 mu m.
14. The method according to claim 13, wherein the total of the Young's moduli in the length and width directions is 350 to 750 kgf / mm &lt; 2 &gt;, the initial tensile strength is 10 kgf / 3.0% by weight, a haze of 3% or less, and a transmittance of 85% or more.