TW202003685A - Polylactic acid-polyolefin alloy resin composition - Google Patents

Abstract

The present invention relates to a polylactic acid-polyolefin alloy resin composition comprising (1) 30 to 90 parts by weight of a polylactic acid resin and (2) 70 to 10 parts by weight of a polyolefin-based resin, wherein the polylactic acid resin (1) comprises a hard segment comprising a polylactic acid repeating unit of Formula 1 and a soft segment comprising a polyolefin-based polyol repeating unit in which polyolefin-based polyol structural units of Formula 2 are linked in a linear or branched manner via a urethane bond or an ester bond, wherein the organic carbon content (%Cbio) of biomass-based carbon, as defined in Equation 1, is at least 60 wt%. The inventive polylactic acid-polyolefin alloy resin composition not only exhibits improved thermal resistance, but also has excellent general properties such as impact and moisture resistance, mechanical properties, and injection processability. Thus, the inventive alloy resin composition can be effectively used as a molding material, and make a great contribution to the prevention of environmental pollution owing to eco-friendly properties thereof.

Description

Polylactic acid-polyolefin alloy resin composition

Field of invention

The present invention relates to a polylactic acid-polyolefin alloy resin composition. More particularly, the present invention relates to an alloy resin composition including a polylactic acid resin and a polyolefin having environmentally friendly properties due to improved heat resistance and excellent general properties (such as impact resistance and resistance Moisture, mechanical properties, injection processability, etc.) and can be effectively used as a molding material.

Background of the invention

Petroleum-based resins such as ethylene terephthalate, nylon, polyolefin, and plasticized polyvinyl chloride (PVC) are widely used today in a wide range of applications, such as packaging materials. However, this petroleum-based resin is not biodegradable, and therefore, causes environmental pollution, for example, excessive emission of greenhouse gases such as carbon dioxide during waste treatment methods. Recently, due to the depletion of petroleum sources, the use of biomass-based resins (typically polylactic acid resins) is widely regarded as an alternative.

However, compared with petroleum-based resins, polylactic acid resins have unsatisfactory heat resistance, moisture resistance, or mechanical properties; therefore, their applicable fields and applications are limited. In particular, attempts have been made to use polylactic acid resins as packaging materials such as packaging films, but they have failed due to poor flexibility of polylactic acid resins.

In order to overcome the limitations of polylactic acid resin, alloy compositions of polylactic acid resin and other general resins and/or engineering plastics have been used. Although molded products containing polylactic acid resins have been prepared from these alloy compositions, due to the incompatibility between the two resins, most cases are limited in improving heat resistance and mechanical properties.

Furthermore, in order to overcome the above problems, it has recently been proposed to add a graft copolymer compatibilizer during the method of forming an alloy of a polylactic acid resin and a polyolefin-based resin (Korean Patent No. 1182936 and early Korean (Patent Publication No. 2012-0128732 and 2012-0117130 cases). However, the resin composition based on polylactic acid and the product prepared by using this graft copolymer compatibilizer or glycidyl methacrylate reaction compatibilizer have the disadvantage of high cost. Furthermore, since the limitation of low compatibility between polylactic acid resin and polyolefin-based resin is overcome, the improvement of its properties is not significant. Therefore, it is difficult to use these compositions for automotive interior materials, which require high durability. Furthermore, because these polylactic acid resin compositions have a wide molecular weight distribution and poor melting characteristics, they cannot be injection molded well, and have poor appearance, mechanical properties, heat resistance, and impact resistance. Furthermore, these compatibilizers have the problem of generating large amounts of total volatile organic compounds (TVOCs) derived from residual solvents, monomers and other volatile organic compounds generated by thermal decomposition during the mixing process. In particular, among the volatile organic compounds, toluene, xylene, styrene, and alkane compounds having 5 to 12 carbon atoms release strongly irritating taste. When people are exposed to air containing these volatile organic compounds for a long time, they may suffer from headache, drowsiness, nausea, difficulty breathing, eyes, nose, and sore throat.

Furthermore, due to the hydrolysis reaction caused by other contained moisture, the polylactic acid resin is easily damaged by moisture. Because of this reaction, the resin is partially degraded into lactic acid monomers or oligomers, thus causing molecular weight degradation.

Furthermore, the resulting lactic acid monomers and oligomers evaporate during a molding process, and can cause equipment contamination or corrosion, or deteriorate the properties of the completed product. In particular, in the case of manufacturing a sheet through extrusion molding, residual lactic acid monomers and oligomers volatilize during the sheet extrusion method, and therefore, cause a thickness change. In the case of manufacturing a sheet by injection molding, the hydrolysis reaction occurs continuously, even after the manufacturing method is completed, it depends on the environment in which the product is used, and therefore, its mechanical properties are deteriorated. In addition, because the polylactic acid resin easily absorbs water by nature, the water is easily absorbed during the execution of a cooling method in a water bath after extrusion, or when a mixed product is stored in pellet form. When these pellets are injection molded, the product will have a poor appearance due to the moisture contained therein, for example, silver bars, and deteriorated physical properties.

Therefore, there is a continuing need for a polylactic acid resin composition having improved heat resistance and moisture resistance and excellent general properties (such as mechanical properties, impact resistance or outflow resistance), and a polylactic acid resin composition that can be reduced after a mixing method The technology of total volatile organic compounds produced from resin while maintaining the unique characteristics of polylactic acid resin.

Summary of the invention

Therefore, an object of the present invention is to provide a polylactic acid-polyolefin alloy resin composition having environmentally friendly properties due to improved flexibility and excellent general properties (such as moisture resistance, mechanical properties, transparency Resistance, heat resistance, resistance, and film processability), and can be effectively used for plastic molding.

According to one method of the present invention, a polylactic acid-polyolefin alloy resin composition is provided, comprising:

(1) 30 to 90 parts by weight of polylactic acid resin and (2) 70 to 10 parts by weight of polyolefin-based resin, wherein the polylactic acid resin (1) contains a hard segment, which contains a The polylactic acid repeating unit of Chemical Formula 1; and a soft segment comprising a polyol repeating unit mainly composed of polyolefins, wherein the polyol structural unit mainly composed of polyolefins of Chemical Formula 2 is passed through an amino group The ester bond or an ester bond is connected in a linear or branched manner, wherein the organic carbon content (%C _bio ) of the biomass-based carbon as defined in Equation 1 is at least 60% by weight, and wherein, in the chemical formula 1 And 2, n is an integer from 700 to 5,000, and m+1 is an integer from 5 to 200:

[Equation 1] %C _bio = (weight ratio of ¹⁴ C isotope to ¹² C total carbon content in polylactic acid resin)/( ¹⁴ C isotope of ¹² total carbon content in carbon standard materials based on biomass to ¹² C weight ratio).

The polylactic acid-polyolefin alloy resin composition according to the present invention not only exhibits improved heat resistance, but also has excellent general properties such as impact resistance and moisture resistance, mechanical properties, and injection processability. Therefore, the alloy resin composition of the present invention can be effectively used for molding, and due to its environmentally friendly nature, it makes a significant contribution to avoiding environmental pollution.

The above and other objects and features of the present invention will become apparent from the following description of the present invention when combined with the accompanying drawings. These figures show:

Figures 1 to 3: Scanning electron microscope (SEM) photographs of the pellets prepared in Examples 1 to 3 are illustrated, and

4 and 5: SEM photographs of pellets prepared in Comparative Examples 2 and 4 are exemplified.

Detailed description of the invention

Thereafter, a polylactic acid-polyolefin alloy resin composition according to one embodiment of the present invention will be explained in detail.

A polylactic acid-polyolefin alloy resin composition of the present invention comprises (1) 30 to 90 parts by weight of polylactic acid resin and (2) 70 to 10 parts by weight of polyolefin-based resin, wherein the polylactic acid The resin (1) comprises a hard segment comprising a polylactic acid repeating unit of Chemical Formula 1; and a soft segment comprising a polyol repeating unit mainly composed of polyolefin, wherein Alkene-based polyol structural units are connected in a linear or branched manner through a monocarbamate bond or an ester bond, where the organic carbon content of the biomass-based carbon as defined in Equation 1 (%C _bio ) is at least 60% by weight, and in formulas 1 and 2, n is an integer from 700 to 5,000, and m+1 is an integer from 5 to 200:

[Equation 1] %C _bio = (weight ratio of ¹⁴ C isotope to ¹² C total carbon content in polylactic acid resin)/( ¹⁴ C isotope of ¹² total carbon content in carbon standard materials based on biomass to ¹² C weight ratio).

(1) Polylactic acid resin

The polylactic acid resin contained in a polylactic acid-polyolefin alloy resin composition according to the present invention basically includes a polylactic acid repeating unit represented by Chemical Formula 1 as a hard segment. Furthermore, the polylactic acid resin includes a polyol repeating unit mainly composed of polyolefin as a soft segment. Here, the polyol repeating unit mainly composed of polyolefin, and the polyol structural unit mainly composed of polyolefin represented by Chemical Formula 2 is passed through a carbamate bond (-C(=O)-NH-) or a The ester bond (-C(=O)-O-) is connected in a linear or branched manner.

Due to the presence of a polylactic acid repeating unit as a hard segment, the polylactic acid resin exhibits characteristics such as environmentally friendly properties and biodegradable characteristics, which is unique to a resin system mainly based on biomass. In addition, according to the experimental data obtained by the inventors of the present application, it was confirmed that the polylactic acid resin exhibits improved flexibility (for example, a relatively low Young's modulus measured in the longitudinal and transverse directions), and due to the use of polyolefin as a soft segment It is the main polyol repeating unit and can produce a film with high transparency and low turbidity. In particular, due to the presence of a combined hard segment and soft segment, the polylactic acid resin reduces the possibility of reduced stability or soft segment (which is the cause of flexibility) outflow. A film containing this polylactic acid resin is less likely to suffer from high turbidity or low transparency. Furthermore, this polylactic acid resin can exhibit the aforementioned benefits without using a large number of soft segments (which is the cause of flexibility); therefore, it can contain a relatively large amount of one of the biomass-based resins, for example, from A hard segment derived from a polylactic acid resin.

At the same time, the polylactic acid resin contains a non-polar soft segment, and therefore, has excellent moisture resistance compared with the conventional polylactic acid resin.

In the polylactic acid resin contained in the polylactic acid-polyolefin alloy resin composition, the organic carbon content (%C _bio ) of the biomass-based carbon defined by Equation 1 may be at least about 60% by weight, At least about 70% by weight, at least about 80% by weight, at least about 85% by weight, at least about 90% by weight, or at least about 95% by weight.

Compared with the polylactic acid-polyolefin alloy resin composition of the present invention using a polyol repeating unit mainly composed of polyolefin, when a repeating unit mainly composed of polyester is used as a soft segment, it is difficult to obtain about 60% by weight of organic carbon content (%C _bio ), because a large number of other resins need to be used, such as a polyester-based polyol repeat unit derived from a petroleum-based source.

The measurement of the organic carbon content (%C _bio ) of biomass-based carbon expressed by Equation 1 can be carried out based on, for example, the standard test method of ASTM D6866 method. After that, the technical significance and measurement method of the organic carbon content (%C _bio ) of the biomass-based carbon will be explained in detail.

In general, unlike organic materials derived from petroleum-based resins, organic materials derived from resins based on biomass (or based on living sources) are known to contain ¹⁴ C isotopes. More specifically, all organic materials taken from living organisms such as animals or plants contain three isotopes in a fixed ratio: ¹² C (about 98.892% by weight), ¹³ C (about 1.108% by weight), and ¹⁴ C (about 1.2 x 10 ^-10 % by weight). This ratio is the same as that of the atmosphere, because carbon is kept constant by the continuous exchange of the environment with the metabolism of living organisms.

At the same time, ¹⁴ C is a radioisotope, and its content decreases with time according to the following equation 2: [Equation 2] n=no‧exp(-at)

Among them, no is the number of ¹⁴ C atoms at the initial stage, n is the number of ¹⁴ C atoms remaining after time t, and a is the decay constant (or radiation decay constant), which is related to the half-life.

In Equation 2, the half-life of ¹⁴ C is about 5,730 years. Considering this decay period, organic materials derived from living organisms that continuously interact with their surroundings, that is, resins based on biomass (based on living sources), can substantially maintain a fixed amount of ¹⁴ C and a fixed isotope The content ratio, for example, a fixed content ratio (weight ratio) of ¹⁴ C/ ¹² C=about 1.2 x 10 ^-12 , even if the isotope content is slightly reduced.

In comparison, fossil fuel systems such as coal or petroleum cannot exchange carbon atoms with the atmosphere for at least 50,000 years. According to equation 2 above, the ¹⁴ C isotope content of organic materials derived from fossil fuel-based resins is at most 0.2% of the initial content; therefore, these materials do not substantially contain ¹⁴ C isotopes.

Equation 1 is based on the technical significance as described above. In Equation 1, the denominator may be the weight ratio of ¹⁴ C/ ¹² C in the biomass-based carbon, for example, about 1.2 x 10 ^-12 , and the numerator may be ¹⁴ C/ ¹² C in a resin sample. Weight ratio. As explained above, based on the fact that the weight ratio of carbon atom isotopes derived from a biomass is maintained at about 1.2 x 10 ^-12 and the weight ratio of carbon atom isotopes derived from fossil fuels is substantially 0, based on the fact that The organic carbon content (%C _bio ) of the substance-based carbon can be measured from a polylactic acid resin contained in a polylactic acid-polyolefin alloy resin composition by using Equation 1. The content and ratio of each carbon isotope can be determined by one of the methods described in the standard ASTM D6866-06 (Standard Test Method for Determination of Biological Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis) measuring. Preferably, the measurement can be performed by mass spectrometry, where a resin sample is reduced to graphite or carbon dioxide gas, and then analyzed in a mass spectrometer or by liquid scintillation spectroscopy. In this mass spectrometry technique, an accelerator and a mass spectrometer are used to separate ¹⁴ C ions from ¹² C ions to measure the content and ratio of each carbon isotope. Alternatively, those skilled in the art can use liquid scintillation spectroscopy to measure the content and ratio of each carbon isotope to calculate the value in Equation 1.

When the organic carbon content (%C _bio ) of the biomass-based carbon measured in Equation 1 is at least about 60% by weight, a polylactic acid resin and a polylactic acid-polyolefin alloy resin composition containing this resin may be Contains a relatively large amount of biomass-based resin and carbon, so it can enhance the environmentally friendly properties and biodegradability.

More specifically, as explained below, a polylactic acid resin containing one of this high organic carbon content (%C _bio ) and a polylactic acid-polyolefin alloy resin composition containing one of this resin can exhibit environmentally friendly properties.

Biochemical products such as polylactic acid resins are biodegradable and release relatively small amounts of carbon dioxide. Compared with petrochemical products, according to the current technological level, the carbon dioxide content released can be reduced by up to 108%, and the energy required to manufacture the resin can be saved by up to 50%. In addition, when a biomass material is substituted for petrochemical fuel for the manufacture of a bioplastic, the CO ₂ emissions calculated by ISO 14000 compatible life cycle analysis (LCA, Life Cycle Assessment Program) can be reduced by up to about 70%.

As a special example, according to NatureWorks, when manufacturing 1 kg of PET resin, 3.4 kg of CO _{2 is} released, and every 1 kg of polylactic acid resin (ie, a bioplastic) releases 0.77 kg of CO ₂ , which shows about 77% reduction in CO ₂ . Furthermore, in terms of energy consumption, this bioplastic requires only 56% of energy compared to the energy consumption of PET. However, the conventional polylactic acid resin has limitations due to low flexibility, and it is observed that when other ingredients such as plasticizers are used to correct the problem, the advantages of bioplastics as described above are significantly impaired.

However, a polylactic acid resin satisfying the high organic carbon content (%C _bio ) as described above and a polylactic acid-polyolefin alloy resin composition containing the resin can exhibit the advantages of bioplastics and can be used for various applications, because the poly The problem of low flexibility of lactic acid resin is solved.

Therefore, a polylactic acid resin that satisfies the high organic carbon content (%C _bio ) as described above and a polylactic acid-polyolefin alloy resin composition containing the resin have the advantages of bioplastics, and therefore can significantly reduce CO ₂ Emissions and energy consumption exhibit environmentally friendly properties. These environmentally friendly properties can be measured by, for example, life cycle assessment of a polylactic acid-polyolefin alloy resin composition.

In the polylactic acid-polyolefin alloy resin composition, the polylactic acid resin may contain about 7.2 x 10 ^-11 to 1.2 x 10 ^-10 % by weight, about 9.6 x 10 ^-11 to 1.2 x 10 ^-10 % by weight, or about 1.08 ¹⁴ C isotope in an amount of x 10 ^-10 to 1.2 x 10 ^-10 % by weight. The polylactic acid resin containing ¹⁴ C isotopes of this content may have a relatively large content of biomass-derived resin and carbon, or substantially the entire resin and carbon, further improving biodegradability and environmentally friendly properties.

In the polylactic acid resin, the hard segment polylactic acid repeating unit can be derived from a biomass, and the soft segment polyolefin-based polyol structural unit can also be derived from a biomass. The polylactic acid structural unit can be obtained, for example, from a polyol resin based on polyolefin, which is derived from a biomass. This biomass can be of any plant or animal origin, for example, one of plant origin such as corn, sugar cane or cassava. In this way, the polylactic acid resin containing polyol structural units derived from polyolefin as the main component and the polylactic acid-polyolefin alloy resin composition containing the resin can contain a relatively large amount of organic carbon content (%C _bio ) For example, at least about 90% by weight or at least about 95% by weight.

In the polylactic acid resin, the hard segment derived from a biomass has at least about 90% by weight, preferably about 95 to 100% by weight, organic carbon content (%C _bio ) as defined by Equation 1; and derived from a biomass The soft segment has an organic carbon content (%C _bio ) as defined in Equation 1 of at least about 70% by weight, preferably about 75 to 95% by weight.

The polylactic acid-polyolefin alloy resin composition containing the biomass-based polylactic acid resin has a high organic carbon content (%C _{bio of} at least about 60% by weight, or at least about 80% by weight of biomass-based carbon ), therefore, meets the criteria for obtaining JBPA's "Biomass Pla" classification (classification based on standard ASTM D6866). Therefore, the polylactic acid resin can properly bear the label of JORA "based on biomass".

In the polylactic acid resin, the polylactic acid repeating unit of Chemical Formula 1 contained in the hard segment may refer to a polylactic acid homopolymer or a repeating unit of this homopolymer. The polylactic acid repeating unit can be obtained according to the conventional method for preparing polylactic acid homopolymer known in the art. For example, a method of forming an L- or D-lactide from L- or D-lactic acid (ie, a cyclic dimer) and performing a ring-opening polymerization reaction, or by L- or D- It is obtained by direct polycondensation reaction of lactic acid. Meanwhile, the ring-opening polymerization method is preferable because it can provide a polylactic acid repeating unit at a higher polymerization degree. Furthermore, the polylactic acid repeating unit can be prepared by copolymerizing L-lactide and D-lactide at a specific ratio to make the copolymer non-crystalline, but the polylactic acid repeating unit is preferably made by Both L-lactide and D-lactide are prepared by polymerization to increase the heat resistance of a film containing this polylactic acid resin. More specifically, an L- or D-lactide material having an optical purity of at least 98% can be subjected to ring-opening polymerization to obtain this polylactic acid repeating unit. Lower optical purity will lower the melting temperature (Tm) of the polylactic acid resin.

At the same time, the polyolefin-based polyol repeating unit contained in the soft segment of the polylactic acid resin has a structure, in which the polyolefin-based polyol structural unit of Chemical Formula 2 is passed through an amino acid The ester bond (-C(=O)-NH-) or monoester bond (-C(=O)-O-) is connected in a linear or branched manner. In particular, the polyol structural unit mainly composed of polyolefin may refer to a polymer prepared from a monomer such as butadiene (for example, poly 1,2-butadiene or poly 1,3-butadiene), or One of the structural units of this polymer, a hydroxyl-terminated polybutadiene (HTPB) in the liquid phase with an average molecular weight of 1,000 to 5,000 prepared from the hydrogenation reaction, may have a hydroxyl group at its terminal.

The terminal hydroxyl group of the prepolymer prepared by the addition polymerization reaction between the terminal hydroxyl group of the polyolefin-based polyol structural unit and the polyhydroxy-based polyol structural unit and the lactide may be combined with Diisocyanates or di- or higher-functionality isocyanate compounds react to form monocarbamate bonds. At the same time, the terminal hydroxyl group of the polyol structural unit mainly composed of polyolefin can react with lactide or a lactic acid derivative compound to form an ester bond (-C(=O)-O-). Polyol-based polyol structural units are connected in a linear or branched manner through this urethane or ester bond to form a polyol-based polyol repeating unit.

The molar ratio of the terminal hydroxyl group of the polyol structural unit mainly composed of polyolefin to the isocyanate group of the diisocyanate or the di- or higher-functionality isocyanate compound may be 1:0.50 to 1:0.99. Preferably, the molar ratio of the terminal hydroxyl group: isocyanate group of the isocyanate group of the polyol structural unit dominated by polyolefin may be about 1:0.60 to about 1:0.95, more preferably about 1:0.70 to About 1: 0.90.

Among them, the polyol structural unit mainly composed of polyolefin is a polymer linearly connected through a monourethane bond, or a repeating unit of this polymer, which can be called a polyurethane polyol repeat Unit, and may have a hydroxyl group at the terminal. Therefore, the polyol repeating unit mainly composed of polyolefin can be used as an initiator for forming the polylactic acid repeating unit in the polymerization reaction method. When the molar ratio of terminal hydroxyl groups: isocyanate groups exceeds 0.99, the number of terminal hydroxyl groups of the repeat unit of the polyurethane polyol is insufficient (OHV<1); therefore, it cannot be suitably used as a starting point Agent. Furthermore, when the molar ratio of hydroxyl groups: isocyanate groups is too low, the terminal hydroxyl groups of the polyol repeating unit dominated by polyolefins become too excessive (OHV>35); therefore, it is difficult to obtain high molecular weight The repeating unit of polylactic acid and polylactic acid resin.

The polymer having a polyol repeating unit mainly composed of polyolefin may have a number average molecular weight of about 1,000 to 100,000, preferably about 10,000 to 50,000. When the number average molecular weight of the polymer having a polyol repeating unit mainly composed of polyolefin is too large or too small, polylactic acid and the film prepared from the polylactic acid-polyolefin alloy resin composition containing polylactic acid may not have Satisfactory flexibility, moisture resistance, and mechanical properties. Furthermore, because the polylactic acid resin cannot have suitable molecular weight properties, this may result in reduced processability of the polylactic acid-polyolefin alloy resin composition, or deteriorated flexibility, moisture resistance, and mechanical properties of the film.

The diisocyanate compound may be any compound having at least two isocyanate groups, as long as it will form a monocarbamate bond with the terminal hydroxyl group of the polyol repeating unit mainly composed of polyolefin: it can be derived from fossil fuels .

Examples of the diisocyanate compound include 1,6-hexamethylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate , 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4' -Bisphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate. The polyfunctional isocyanate compound having at least three isocyanate functional groups can be selected from the oligomer of the diisocyanate compound, the polymer of the diisocyanate compound, the cyclic polymer of the diisocyanate compound, and hexamethylene di The group consisting of isocyanate isocyanurate, triisocyanate compounds, and these isomers. In addition, various other diisocyanate compounds known in the art can be used without particular restrictions. Considering the ability to impart flexibility to the polylactic acid resin, 1,6-hexamethylene diisocyanate is preferred.

Meanwhile, the polylactic acid resin contained in the composition may include a terminal carboxyl group of the polylactic acid repeating unit contained in the hard segment via an ester bond with the polyolefin contained in the soft segment. A block copolymer connected by terminal hydroxyl groups of the main polyol structural unit, or a block copolymer in which the block copolymer is connected in a linear or branched manner through a carbamate bond.

In particular, in the block copolymer, the terminal carboxyl group of the polylactic acid repeating unit may be connected to the terminal hydroxyl group of the polyurethane polyol repeating unit via an ester bond. For example, the chemical structure of the block copolymer can be represented by the following general formula 1: [Formula 1] polylactic acid repeating units (L)-(E)-polyol-based polyol repeating units (OUOUO)-(E) -Polylactic acid repeating unit (L)

[Formula 2] Polylactic acid repeating unit (L)-(E)-polyol-based polyol structural unit (O)-(E)-polylactic acid repeating unit (L)-(U)-polylactic acid repeating Unit (L)-(E)-polyol-based polyol structural unit (O)-(E)-polylactic acid repeating unit (L),

Among them, O refers to a polyol structural unit mainly composed of polyolefin, U refers to a carbamate bond, and E refers to an ester bond.

Because the polylactic acid resin includes a block copolymer in which the polylactic acid repeating unit and the polyolefin-based polyol structure or repeating unit are connected together, it suppresses the polyolefin-based polyvalent Alcohol structure or repeating units flow out. Therefore, the resulting film may have excellent moisture resistance, transparency, mechanical properties, heat resistance, or anti-caking properties. In addition, because at least some polylactic acid structures or repeating units and polyol repeating units dominated by polyolefins have a block copolymer type, the molecular weight distribution, glass transition temperature (Tg), and melting temperature (Tm) of the polylactic acid resin can be It is optimized, and the mechanical properties, flexibility, heat resistance, etc. of the film produced therefrom can be improved.

However, it is not necessary to connect all the polylactic acid repeating units contained in the polylactic acid resin with the polyol structure or repeating unit mainly composed of polyolefin to form a block copolymer. At least some of the polylactic acid repeating unit may be a polylactic acid homopolymer that is not combined with a polyol structure or repeating unit based on polyolefin. In this case, the polylactic acid resin may be a mixture including: a terminal carboxyl group of the polylactic acid repeating unit contained in the hard segment is linked to the polyolefin contained in the soft segment through an ester bond A block copolymer in which the terminal hydroxyl group of the main polyol structural unit is connected, a block copolymer prepared by connecting the block copolymer through a urethane bond in a linear or branched manner, And a polylactic acid homopolymer that remains uncoupled from the polyol repeating unit based on polyolefin.

Meanwhile, based on 100 parts by weight of the total polylactic acid resin (when the polylactic acid homopolymer is selectively included, 100 parts by weight is the sum of the weights of the block copolymer and the homopolymer), the polylactic acid resin may contain about 65 To 95 parts by weight, about 80 to 95 parts by weight, or hard segments in an amount of about 82 to 92 parts by weight; and about 5 to 35 parts by weight, about 5 to 20 parts by weight, or about 8 to 18 parts by weight Soft segment.

If the amount of the soft segment is 35 parts by weight or less, a polylactic acid resin having a high molecular weight can be provided, and its mechanical properties (eg, film strength, etc.) can be enhanced. In addition, the transport properties, processability or dimensional stability of this film during the packaging process can be improved. Furthermore, if the content of the soft segment is about 5 parts by weight or more, the flexibility and moisture resistance of the polylactic acid and the film prepared therefrom can be improved. In particular, the glass transition temperature of the polylactic acid resin is appropriate, and therefore, the flexibility of the film can be improved. Furthermore, the polyol structure or repeating unit of polyolefin as the main component of the soft segment can be used as a synergist. Therefore, it can avoid the reduction of polymerization conversion rate and form a polylactic acid resin with high molecular weight.

The polylactic acid resin in the polylactic acid-polyolefin alloy resin composition may have a number average molecular weight of about 50,000 to 200,000, preferably about 50,000 to 150,000. Furthermore, the polylactic acid resin may have a weight average molecular weight of about 100,000 to 400,000, preferably about 100,000 to 320,000. The molecular weight affects the processability of the polylactic acid-polyolefin alloy resin composition and the mechanical properties of the film. When the number average molecular weight is about 50,000 or more and the weight average molecular weight is about 100,000 or more, the melt viscosity of the resin is suitable during the melting method such as extrusion, and therefore, the film processability and mechanical properties such as strength can be improved. Furthermore, when the number average molecular weight is about 200,000 or less and the weight average molecular weight is about 400,000 or less, the resin can have good processability and productivity due to its suitable melt viscosity.

In addition, the polylactic acid resin may have a molecular weight distribution (Mw/Mn) of about 1.60 to 3.0, preferably about 1.80 to 2.15, which is defined by the ratio of weight average molecular weight (Mw) to log average molecular weight (Mn). When the molecular weight distribution of the polylactic acid resin is within this range, the resin has appropriate melt viscosity and melting properties during the melting method such as extrusion, so that it can be efficiently processed and extruded into a film, and the film containing the polylactic acid resin Show good mechanical properties such as strength. Conversely, when the molecular weight distribution of the polylactic acid resin is too narrow, the melt viscosity becomes too high and it becomes difficult to process and extrude the composition into a film. If the molecular weight distribution is too wide, such mechanical properties as film strength will decrease, and its melting properties will deteriorate, for example, resulting in too low a melt viscosity, and therefore, it will become difficult to extrude the composition into a film, or a film formed Will be in poor extrusion conditions.

Furthermore, the polylactic acid resin may have a melting temperature (Tm) of about 145 to 178°C, preferably about 160 to 178°C, or about 165 to 175°C. When the melting temperature is about 145°C or more, the film prepared from the polylactic acid resin can have good heat resistance. If the melting temperature is about 178°C or less, the polylactic acid resin can have good film processability.

In addition, the polylactic acid resin, for example, the block copolymer contained therein, has a glass transition temperature (Tg) of about 20 to 55°C, or about 25 to 55°C, or about 30 to 55°C. When the polylactic acid resin has the glass transition temperature range, a film containing this resin composition can have optimized flexibility and stiffness, and thus can be preferably used as a packaging film. If the glass transition temperature of the polylactic acid resin is about 20°C or greater, a film prepared from it exhibits suitable stiffness, and therefore can have good shipping properties, processability, and dimensional stability during the packaging method using this film , Or anti-caking. Furthermore, if the film has a glass transition temperature of about 55°C or less, the film shows good flexibility and improved adhesion strength to the adhesion interface with the target to be wrapped, and because of reduced noise, the film can be used as a wrap.

Meanwhile, the polylactic acid-polyolefin alloy resin composition may contain less than about 1% by weight of residual monomers per part by weight of the polylactic acid resin contained therein (preferably about 0.01 to 0.5% by weight (e.g. , Used to form lactide monomers of polylactic acid repeat units). Because the polylactic acid-polyolefin alloy resin composition includes a block copolymer with a special structural feature and a polylactic acid resin containing the block copolymer, and a selective antioxidant, most of the lactic acid used in the preparation method The lactide monomer participates in the polymerization reaction and forms a polylactic acid repeating unit; and the depolymerization or degradation of the polylactic acid resin does not actually occur. Therefore, the polylactic acid-polyolefin alloy resin composition can keep the residual monomer (for example, residual lactide monomer, etc.) to a minimum.

If the content of the residual monomer is less than about 1% by weight, the problem of odor will not occur in the film forming method using this polylactic acid-polyolefin alloy resin composition, and protection will increase the strength of the final film, because the polylactic acid resin has suitable Molecular weight, and this film can be suitably applied to food packaging.

(2) Polyolefin resin

The polyolefin resin contained in the polylactic acid-polyolefin alloy resin composition according to the present invention can be used to enhance the properties of the polylactic acid resin. A highly crystalline polymer containing propylene as one of its main components can be used to optimize the properties of the composition such as impact resistance, stiffness, durability, heat resistance, and the like.

The polyolefin resin may be a homopolymer of propylene, or a copolymer formed from propylene and an aliphatic α -olefin and/or aromatic olefin having 2 to 20 carbon atoms (excluding 3 carbon atoms), preferably propylene Homopolymer or copolymer formed from propylene and aliphatic α -olefins and aromatic olefins having 2 to 8 carbon atoms (except 3 carbon atoms), more preferably propylene homopolymer or propylene and at least one option Copolymers prepared from olefins consisting of ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. The polyolefin resin may further contain ethylene in an amount of 0 to 20 mol%, preferably 0.1 to 15 mol%.

The polyolefin resin may be a highly crystalline polyolefin resin, for example, a highly crystalline homopolypropylene, a highly crystalline block polypropylene, and a highly crystalline random polypropylene.

The highly crystalline polyolefin resin may have a melting temperature of 150°C or greater, preferably 165 to 170°C, 120°C or greater, preferably a crystallization temperature of 124 to 130°C, and 120°C or greater, The best is the heat distortion temperature of 130 to 140 ℃.

Furthermore, the highly crystalline polyolefin resin may have a melt index of 5 to 100 g/10 min (230°C, 2.16 kg), preferably 10 to 50 g/10 min, more preferably 20 to 40 g/10 min (ASTM D1238). When the melt index is in this range, the resin has good compatibility with polylactic acid resin, has an excellent appearance, and can be easily extruded. Meanwhile, in the present invention, the polyolefin resin may be a polyolefin resin having a melt index of 20 g/10 minutes or less, a polyolefin resin having a melt index of 20 g/10 minutes or more, or this Wait for the mixture.

The polyolefin resin may have a weight average molecular weight of 100,000 to 700,000.

The polyolefin resin may have a flexural modulus of 14,000 kg/cm ² or more, preferably 15,000 to 19,000 kg/cm ² .

Furthermore, when judged by the xylene solubles (Xs) test, the polyolefin resin is preferably a highly crystalline polyolefin resin having a polypropylene random portion of 12% or less, more preferably a Highly crystalline polyolefin resin with 5% or less random part of polypropylene. Xs test is a method for measuring random parts according to ASTM D5492 (or ISO 16152). According to this method, a polypropylene resin is completely soluble in xylene to precipitate regular components that are insoluble at room temperature. Then, the precipitate was separated by filtration and dried, and the remaining xylene solution was placed in a Soxhle extractor to extract propylene monomer. The extract thus obtained is a random component, which is used to calculate the random part.

When measured by C ¹³ NMR spectroscopy, the polypropylene resin may have a regularity index (II) of 95% or more. When II is in this range, the resin composition can have excellent heat resistance, impact resistance, and scratch resistance. The technique of C ¹³ NMR spectroscopy is disclosed in A. Zambeli et al., and this method measures the meso pentad of polypropylene by detecting the signal of the methyl group measured by C ¹³ NMR. The meso-five-unit composition rate is the fraction of propylene monomer units present in one chain, where five propylene monomer units are continuously meso-bonded. If the meso-five unit ratio is high, the propylene resin has high crystallinity and improved mechanical properties.

The polyolefin resin may have organic carbon mainly based on biomass. Biomass-based organic carbon can be obtained, for example, by microbial fermentation or fermentation of recyclable carbon sources (mostly corn starch and sugar cane juice) to produce single-chain organic solvents (mostly reduced alcohols). The ethanol obtained based on biomass can therefore be used to produce bio-ethylene, as described in Morschbacker AL, 2009, BioEthanol Based Ethylene, Journal of Macromolecular Science , Part C: Polymer Reviews, 49: 79-84 Used as a monomer during the production of polyethylene during dehydration. Furthermore, n-propanol, mainly biomass, can be dehydrated to form propylene, which is then polymerized into polypropylene by a cost-effective method for making bioplastics.

Based on 100 parts by weight of the polylactic acid-polyolefin alloy resin composition, the polyolefin resin may be 10 to 70% by weight, preferably 30 to 60% by weight. When the amount of polyolefin resin is in this range, it has good compatibility with polylactic acid resin, excellent heat resistance, appearance, and impact resistance.

The polylactic acid-polyolefin alloy resin composition may further include an impact modifier.

The impact modifier may be selected from an olefin-based impact modifier, an acrylic-based impact modifier, and a methacrylate/butadiene/styrene (MBS)-based Impact modifier, an impact modifier based on styrene/ethylene/butadiene/styrene (SEBS), an impact modifier based on silicon, and an elastomer based on polyester At least one of the impact modifiers. Preferably, the impact modifier can be an olefin-based impact modifier, more preferably a copolymer of ethylene-α-olefin.

Olefin-based impact modifiers are economical and exhibit excellent impact resistance and good compatibility with polypropylene. In particular, the copolymer mainly composed of ethylene-α-olefin shows excellent elasticity, flexibility, and impact resistance. The ethylene-α-olefin-based copolymer is preferably prepared by a metallocene catalyst.

The polylactic acid resin in the polylactic acid-polyolefin alloy resin composition of the present invention contains a polyol component mainly composed of polyolefin in the polymer structure of the polylactic acid resin, and shows an impact with an acrylic acid mainly Modifier, an impact modifier mainly based on methacrylate/butadiene/styrene (MBS), an impact modifier mainly based on styrene/ethylene/butadiene/styrene (SEBS) Agent, a silicon-based impact modifier, and a polyester-based impact modifier with good compatibility; therefore, it can be used with any impact modifier without limitation.

Based on the total of 100 parts by weight of (1) polylactic acid resin and (2) polyolefin-based resin, the impact modifier can be 20 parts by weight or less, preferably 0.1 to 20 parts by weight, more preferably Use in an amount of 5 to 10 parts by weight.

When the impact modifier is in this range, the compatibility between the polylactic acid resin and the polyolefin-based resin is good, and the polylactic acid-polyolefin alloy resin composition prepared therefrom shows significantly improved impact resistance and plasticity. And heat resistance. Because the impact modifier improves the heat resistance and injection processability by reducing the crystallization rate and content of the polylactic acid-polyolefin alloy resin composition, problems such as reduced heat resistance of molded parts and poor appearance may be caused by impact Occurs when the content of the modifier exceeds 20 parts by weight.

Meanwhile, the polylactic acid-polyolefin alloy resin composition may contain an antioxidant. Antioxidants can inhibit the yellowing of polylactic acid resins, and therefore, improve the appearance of polylactic acid-polyolefin alloy resin compositions and films prepared therefrom. Furthermore, antioxidants can inhibit the oxidation or thermal degradation of soft segments.

For this purpose, the polylactic acid-polyolefin alloy resin composition may contain about 100 to 3,000 ppmw based on the amount of monomers (for example, lactic acid or lactide) used to form the polylactic acid repeating unit of the polylactic acid resin. Antioxidants in amounts of about 100 to 2,000 ppmw, about 500 to 1,500 ppmw, or about 1,000 to 1,500 ppmw.

When the content of the antioxidant is about 100 ppmw or more, yellowing of the polylactic acid resin caused by the oxidation of the flexible component such as the soft segment can be avoided, and the polylactic acid-polyolefin alloy resin composition and its preparation The appearance of the film may be good. Furthermore, when the content of the antioxidant is about 3,000 ppmw or less, the polymerization rate of lactide is kept appropriate, and the antioxidant helps the hard segment containing the repeating unit of polylactic acid to be produced. Therefore, the mechanical properties of the polylactic acid resin can be improved.

When the antioxidant is used in an optimal amount (for example, when the polylactic acid resin and the polylactic acid-polyolefin alloy resin composition are obtained by adding a specific amount of antioxidant during the polymerization of the polylactic acid resin), the polylactic acid resin The degree of polymerization conversion and polymerization reaction can be increased, and productivity can be increased. Furthermore, since the film formation method of the polylactic acid-polyolefin alloy resin composition at more than 180°C exhibits better thermal stability, monomers such as lactide or lactic acid or low molecular weights such as cyclic oligomer chains can be suppressed Material formation.

Therefore, a packaging film can be provided, which not only has a better appearance due to the suppression of molecular weight reduction and film color change (yellowing), but also has improved flexibility and general properties such as mechanical properties, heat resistance, anti-caking resistance, etc. nature.

As for antioxidants, one or more are selected from an antioxidant based on hindered phenol, an antioxidant based on amine, an antioxidant based on sulfur, and an antioxidant based on phosphite Antioxidants can be used, and other known antioxidants that can be applied to the polylactic acid-polyolefin alloy resin composition can also be used.

However, because the polylactic acid-polyolefin alloy resin composition may have a monoester repeating unit, the resin composition is easily oxidized or thermally degraded during a high-temperature polymerization reaction or a high-temperature extrusion or shaping method. Therefore, it is preferable to use the above-mentioned thermal stabilizer, polymerization stabilizer, or antioxidant as an antioxidant. Specific examples of antioxidants include thermal stabilizers based on phosphoric acid, such as phosphoric acid, trimethyl phosphate, or triethyl phosphate; primary antioxidants based on hindered phenols, such as 2,6-di-tertiary butyl -P-cresol, octadecyl-3-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, tetrakis[methylene-3-(3,5-di-tert Tributyl-4-hydroxyphenyl) propionate) methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl ) Benzene, 3,5-di-tert-butyl-4-hydroxybenzyl phosphite diethyl ester, 4,4'-butylene-bis(3-methyl-6-tert-butylphenol) , 4,4'-thiobis(3-methyl-6-tert-butylphenol), or bis[3,3-bis-(4'-hydroxy-3'-tert-butyl-phenyl) Butyric acid]diol ester; secondary antioxidants based on amines, such as phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenedi Amine, or N,N'-di-β-naphthyl-p-phenylenediamine; secondary antioxidants mainly based on sulfur, such as dilauryl disulfide, dilauryl thiopropionate, Distearylthiopropionate, mercaptobenzothiazole, or tetramethylthiuram disulfide tetra[methylene-3-(laurylthio)propionate] methane; or as phosphite Mainly secondary antioxidants, such as triphenyl phosphite, tri(nonylphenyl) phosphite, triisodecyl phosphite, bis(2,4-third butylphenyl) pentaerythritol disulfite Phosphate, or (1,1'-diphenyl)-4,4'-diyl bisphosphate tetra[2,4-bis(1,1-dimethylethyl)phenyl] ester. Among them, it is best to use an antioxidant based on phosphite in combination with other antioxidants.

In addition to the above impact modifiers and antioxidants, the polylactic acid-polyolefin alloy resin composition may further include various known additives, such as anti-hydrolysis agents, nucleating agents, organic or inorganic fillers, plasticizers, chain elongation Agents, UV stabilizers, color blockers, antiglare agents, deodorants, flame retardants, weathering agents, antistatic agents, mold release agents, oxidation inhibitors, ion exchangers, colorants, and inorganic or organic particles , As long as it does not have a negative effect on the general properties of the polylactic acid-polyolefin alloy resin composition.

The anti-hydrolysis agent is a reactive compound that can react with terminal hydroxyl groups or hydroxyl groups of polylactic acid. The anti-hydrolysis agent can increase the anti-hydrolysis property and durability. In other words, the anti-hydrolysis agent can be applied to an ester-based resin, such as polyester, polyamide, polyurethane, etc., to prevent the resin composition from being exposed to water or acid through the terminal of the polymer chain The end cap at the place reacts and hydrolyzes. The anti-hydrolysis agent can be carbodiimides, for example, modified phenylcarbodiimide, poly(tolylcarbodiimide), poly(4,4'-diphenylmethane carbodiimide (Imide), poly(3,3'-dimethyl-4,4'-diphenylene carbodiimide), poly(p-lane phenylene carbodiimide), poly(inter -Phenylenecarbodiimide), or poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide). Based on 100 parts by weight of polylactic acid and polypropylene resin, the anti-hydrolysis agent can be used in an amount of about 5% by weight.

Based on 100 parts by weight of the polylactic acid-polyolefin alloy resin composition (including the nucleating agent), the nucleating agent can be used in an amount of about 10% by weight, preferably 5% by weight. When the resin composition is included in the nucleating agent in this range, its heat resistance and injection moldability can be improved. The nucleating agent may be a metal salt of sorbitol, a metal phosphate, a quinacridone, a calcium carboxylate, and an organic compound mainly based on amide, preferably a metal salt mainly based on phosphate.

Examples of plasticizers include phthalate plasticizers, such as diethyl phthalate, dioctyl phthalate, and dicyclohexyl phthalate; aliphatic dibasic acid ester plasticizers, such as adipic acid dibasic -1-butyl, di-n-octyl adipate, di-n-butyl sebacate, and di-2-ethylhexyl azelate; phosphate plasticizers, such as diphenyl-2-ethyl phosphate Hexyl and diphenyloctyl phosphate; polyhydroxycarboxylic acid ester plasticizers, such as tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and tributyl citrate; Aliphatic ester plasticizers, such as acetyl ricinoleic acid methyl, and amyl stearate; polyhydric alcohol ester plasticizers, such as glycerin triacetate; and epoxy plasticizers, Such as, epoxidized soybean oil, epoxidized linseed oil fatty acid butyl ester, and epoxidized octyl stearate.

Furthermore, examples of coloring pigments include inorganic pigments, such as carbon black, titanium oxide, zinc oxide, and iron oxide; and organic pigments, such as cyanine pigments, phosphoquinones, taxones, and isoindones Dolphinones, and thioindigos.

When the polylactic acid-polyolefin alloy resin composition is used to prepare a film, inorganic or organic particles can be used to improve the anti-caking properties of the film. Based on 100 parts by weight of the polylactic acid-polyolefin alloy resin composition, the amount of inorganic or organic particles may be about 30% by weight, preferably about 10% by weight. Examples of inorganic or organic particles may include silica, colloidal silica, alumina, alumina sol, talc, titanium dioxide, mica, calcium carbonate, polystyrene, polymethyl methacrylate, silicon, and the like. The surface treatment of the silica, titanium dioxide or talc is not particularly limited. In the case where surface-treated titanium dioxide or talc is used, it gives the film a good balance of overall properties including stiffness and impact resistance, and its properties such as reduced specific gravity, heat resistance and injection moldability can also be improved. Surface treatment can be carried out by a chemical or physical method such as a silane coupling agent, a higher fatty acid, a fatty acid metal salt, a saturated fatty acid, an organic titanate, a resin acid, polyethylene glycol, etc. Implementation. The average particle size of the inorganic particles may be 1 to 30 μm, preferably 1 to 15 μm. When the average particles are within this range, a film containing these particles shows improved heat resistance and stiffness.

Furthermore, various additives that can be applied to the polylactic acid-polyolefin alloy resin composition or its film can be used, and the types of these and the type of hydrocarbons purchased are known to those skilled in the art.

At the same time, the polylactic acid-polyolefin alloy resin composition may have a color-b value of less than 10, preferably 5 or less, in the pellet product. Because the yellowing of the polylactic acid resin can be reduced by containing an antioxidant in the resin composition, it can have a color-b value of less than 10. If the color-b value of the resin composition is less than 10, when it is used as a film, the appearance of the film can be good and the product value can be improved.

Thereafter, the preparation method of the polylactic acid-polyolefin alloy resin composition of the present invention will be explained in detail.

<Preparation of polyol structural units based on polyolefins>

First, a hydroxyl group is introduced to the terminal of a polymer (poly1,2-butadiene or poly1,3-butadiene) prepared by copolymerization of butadiene monomer, and then, by A (co)polymer containing polyol structural units mainly composed of polyolefins is obtained by performing a hydrogenation reaction from the formation of hydroxyl terminated polybutadiene (HTPB) having a number average molecular weight of 1,000 to 3,000. This method can be carried out by a conventional method for preparing polyol (co)polymers based on polyolefins.

<Preparation of Polyol-based Polyol Repeating Unit A>

Then, a (co)polymer containing polyol structural units mainly composed of polyolefin, a functional isocyanate compound, and a carbamate reaction catalyst are packed in a reactor, and accepted during heating and stirring Monocarbamate reaction. As a result of this reaction, the two isocyanate groups of the diisocyanate compound are combined with the terminal hydroxyl groups of the (co)polymer to form a monocarbamate bond. Therefore, a (co)polymer containing a repeating unit of a polyurethane polyol is formed, in which the polyol structural unit mainly composed of polyolefin is in a linear or branched manner through a polyurethane bond Connected, these units serve as one of the soft segments in the polylactic acid resin. Polyurethane polyol (co)polymer can be in the form of EUEUE or EU(-E)-EUE, in which the polyol repeating unit (O) based on polyolefin is passed through monourethane The bond (U) is connected in a linear or branched manner, and the polyol repeating unit dominated by polyolefin is attached at the two terminals.

<Preparation of Polyol-based Polyol Repeating Unit B>

Furthermore, a (co)polymer containing polyol structural units mainly composed of polyolefin, lactic acid (D- or L-lactic acid), lactide (D- or L-lactide), and a condensation reaction catalyst Or a ring-opening polymerization catalyst is packed in a reactor and undergoes a polyesterification reaction or a ring-opening polymerization reaction. Due to this reaction, the lactic acid (D- or L-lactic acid) or lactide (D- or L-lactide) is bonded to the hydroxyl group of the (co)polymer to form an ester bond. Therefore, a (co)polymer comprising a polylactic acid resin repeating unit (L) and a polyolefin-based polyol repeating unit is formed, in which the polyolefin-based polyol structural unit is passed through an ester bond Connect in a linear or branched manner. Polyol-based polyol and polylactic acid resin (co)polymer can be in the form of LEOEL, in which the polyolefin-based polyol repeat unit (O) is repeated with the polylactic acid resin via an ester bond (E) The unit is connected at the two terminals.

The two or more isocyanate groups of the diisocyanate compound and the terminal hydroxyl group of the (co)polymer are combined in a linear or branched manner to form a monocarbamate bond. Therefore, the polylactic acid resin can be obtained in the final form of L-E-O-E-L-U-L-E-O-E-L.

At this time, the polyolefin-based polyol repeating unit prepared from butadiene can be derived from biomass-based (for example, a plant-derived); therefore, polyolefin-based polyol (co)polymer It can have a very high organic carbon content (%C _bio ) of at least 70% by weight.

The carbamate reaction can be carried out in the presence of a tin catalyst, for example, tin octoate, dibutyltin dilaurate, dioctyltin dilaurate and the like. In addition, the urethane reaction can be carried out under typical reaction conditions used to prepare polyurethane resins. For example, isocyanate compounds and polyol (co)polymers based on polyolefins are present in the presence of a monocarbamate reaction catalyst, under nitrogen atmosphere at 70 to 80°C for 1 to 5 hours, resulting in One (co)polymer of polyolefin polyol repeating units.

Thereafter, the polylactic acid-polyolefin alloy resin composition containing the block copolymer (or the polylactic acid resin containing the copolymer) and the antioxidant can be In the presence of a (co)polymer, it is prepared by polycondensation of lactic acid (D- or L-lactic acid) or ring-opening polymerization of lactide (D- or L-lactide). That is, according to these polymerization reactions, a polylactic acid resin having a polylactic acid repeating unit as a hard segment is formed, while yellowing of the resin due to oxidation of the soft segment can be suppressed by an antioxidant. During this process, the polyurethane polyol repeating unit is bonded to at least some of the terminal groups of the polylactic acid repeating unit to produce a block copolymer.

Furthermore, a prepolymer can be prepared by combining a polyol based on polyolefin and lactide. Then, the prepolymer can undergo a chain extension reaction with one of the diisocyanate compounds to obtain a known polylactic acid-based copolymer, and a reaction with an isocyanate compound having at least two functional groups to obtain a known branched type of copolymerization And the polylactic acid-polyolefin alloy resin composition containing this copolymer can be prepared.

Meanwhile, the ring-opening polymerization of lactide can be carried out in the presence of a metal catalyst, such as alkaline earth metals, rare earth metals, transition metals, aluminum, germanium, tin, and antimony. More specifically, the metal catalyst may be in the form of carbonate, alkoxide, halide, oxide, or carbonate. Preferably, zinc octoate, titanium tetraisopropoxide, or aluminum triisopropoxide can be used as a metal catalyst.

In addition, the formation of polylactic acid repeat units, such as the ring-opening polymerization reaction of lactide, can be carried out continuously in the same reactor where the carbamate reaction has occurred. In other words, a polyolefin-based polyol polymer and an isocyanate compound undergo a monocarbamate reaction to produce a polymer containing polyolefin-based polyol repeat units, and then, such as lactide The monomer and catalyst are continuously added to the same reactor in order to obtain a polylactic acid repeating unit. Therefore, a polymer including a polyol repeating unit mainly composed of polyolefin serves as an initiator, and a polylactic acid repeating unit and a polylactic acid resin including the repeating unit can be continuously manufactured with high yield and productivity. In a similar manner, a polyol based on polyolefins undergoes a ring-opening polymerization reaction with a lactide starter, and then, an isocyanate compound is continuously added to the same reactor to carry out a chain extension reaction in order to achieve high yield Rate and productivity to obtain a polylactic acid repeating unit and a polylactic acid resin containing the repeating unit.

Because the polylactic acid-polyolefin alloy resin composition contains a block copolymer (polylactic acid resin), in which specific hard segments and soft segments are combined, it can exhibit more improved flexibility and show polylactic acid Resin biodegradability. Furthermore, this resin composition can minimize the outflow of the soft segment causing the flexibility, and can largely avoid the moisture resistance, mechanical properties, heat resistance, transparency, or turbidity of the film caused by the soft segment. Reduction.

In addition, the polylactic acid-polyolefin alloy resin is prepared to have a special glass transition temperature, and one of the special melting temperatures (Tm). Therefore, a film prepared therefrom exhibits optimized flexibility and stiffness as a packaging material, and also has good melt processability, anti-blocking property, and heat resistance. Therefore, the polylactic acid resin and the polylactic acid-polyolefin alloy resin composition containing the resin can be preferably used as a packaging material such as a film.

Furthermore, in the preparation method or in use, the polylactic acid resin can be suppressed due to the presence of antioxidants, and the polylactic acid-polyolefin alloy resin composition containing these components can be manufactured with flexibility such as significant improvement A packaging film with better general properties and excellent mechanical properties can also have better appearance and product quality.

In other words, the polylactic acid-polyolefin alloy resin composition of the present invention contains a polyol repeating unit mainly composed of polyolefin as a soft segment, and therefore, the film prepared from the polylactic acid-polyolefin alloy resin composition since then exhibits a significant improvement Flexible.

Furthermore, polyols based on polyolefins, which are non-polar soft segments compared to polylactic acid resins (ie, hard segments), can reduce the moisture content of the resin, and the moisture resistance of the resin can be significantly improved.

Thereafter, the functions and effects of the present invention will be more clearly explained by the following examples. However, these examples are provided for illustrative purposes only, and the present invention is not limited thereto.

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

1. Polyol-based polyol repeating units and their counterparts

-HTPB 1.0: hydroxyl-terminated polybutadiene (HTPB) with a molecular weight of 1,000, which is led to a butadiene monomer-conjugated polymer (poly1,2-butadiene by introducing a hydroxyl group Or poly 1,3-butadiene) terminal group, and then prepared by hydrogenation reaction.

-HTPB 2.0: hydroxyl-terminated polybutadiene (HTPB) with a molecular weight of 2,000, which is a conjugated polymer (poly1,2-butadiene) by introducing a hydroxyl group to one of the butadiene monomers The terminal group of ene or poly 1,3-butadiene) is prepared after hydrogenation reaction.

-HTPB 3.0: hydroxyl-terminated polybutadiene (HTPB) with a molecular weight of 3,000, which is a conjugated polymer (poly1,2-butadiene) by introducing a hydroxyl group to one of the butadiene monomers The terminal group of ene or poly 1,3-butadiene) is prepared after hydrogenation reaction.

-HTPB 5.0: hydroxyl-terminated polybutadiene (HTPB) with a molecular weight of 5,000, which is a conjugated polymer (poly1,2-butadiene) by introducing a hydroxyl group to one of the butadiene monomers The terminal group of ene or poly 1,3-butadiene) is prepared after hydrogenation reaction.

-PEG 8.0: polyethylene glycol having an average molecular weight of 8,000.

-PBSA 11.0: aliphatic polyester polyol prepared by polycondensation reaction of 1,4-butanediol, succinic acid, and adipic acid with a number average molecular weight of 11,000.

2. Diisocyanate compounds and isocyanates with at least three functional groups

-HDI: hexamethylene diisocyanate

-TDI: 2,4- or 2,6-toluene diisocyanate (toluene diisocyanate: TDI)

-D-L75: Bayer, Desmodur L75 (trimethylolpropane + 3 toluene diisocyanate)

3. Lactide monomer

-L- or D-lactide: manufactured by Purac and containing only biomass organic carbon with optical purity of 99.5% or higher

4. Antioxidants, etc.

-TNPP: tris(nonylphenyl) phosphite

-U626: bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite

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

-PEPQ: (1,1'-diphenyl)-4,4'-diyl bisphosphoric acid tetra[2,4-bis(1,1-dimethylethyl)phenyl] ester

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

-O3: bis[3,3-bis-(4'-hydroxy-3'-third butyl-phenyl) butyric acid] glycol ester

5. Polyolefin resin, etc.

-JSS-370N: polyethylene-propylene block copolymer, manufactured by Honam Petrochemical Corp., having a melt index of 35 g/10 min (230°C, 2.16 kg), a heat distortion temperature of 135°C, and 10 to 12% by weight of Xs

-SEETEC M1400: polyethylene-propylene block copolymer, which is manufactured by LG Chem., has a melt index of 8 g/10 min (230°C, 2.16 kg), a heat distortion temperature of 105°C, and 95 to 96% Of II

-SHC7260: Biomass-based polyethylene manufactured by Braskem, with a melt index of 7.2 g/10 min (230°C, 2.16 kg), a heat distortion temperature of 76°C, and a biological content of 94%

6. Impact modifier, etc.

-G1701: block copolymer of styrene/ethylene/propylene, which is manufactured by KRAPTON, has a stiffness of 72 HD (Shore A, 30s), and 37% by weight styrene

-LC170: Ethylene-1-octene copolymer, which is manufactured by LG Chem. and has a stiffness of 71 HD (Shore A, 30s)

-MB838A: Block copolymer based on methacrylate/butadiene/styrene (MBS), which is manufactured by LG Chem. and has a stiffness of 71 HD (Shore A, 30S)

-Biostrength 150: Core/shell impact modifier mainly based on acrylic, manufactured by ARKEMA

7. Inorganic filler and nucleating agent, etc.

-SP-3000: Talc, which is manufactured by Dawon Chem., has an average particle size of 2.5 μm, and a bulk density of 0.32 g/cm ²

-EMforce ^TM Bio: CaCO ₂ , manufactured by Special Mineral, has an average particle size of 1.0 μm and an aspect ratio of 5.4

-TF-1: N,N',N"-tricyclohexyl-1,3,5-benzenetrimethylamide, which is manufactured by NJC Co.,Ltd.

-NA-11: 2,2'-methylenebis(4,6-di-tert-butylphenol) sodium phosphate, manufactured by Asahi Denka

8. Anti-hydrolysis agent and chain extender

-BioAdimide 100: carbodiimide polymer manufactured by Rhein Chemie

9. Compatibilizer, etc.

-AX8840: Ethylene-maleic anhydride graft-glycidyl methacrylate copolymer, which is manufactured by Arkema and has a graft ratio of 8.0%

-PH-200: propylene-maleic anhydride graft copolymer, which is manufactured by Honam petrochemical Corp. and has a graft ratio of 3.9%

Preparation Examples 1 to 6: Preparation of polylactic acid resins A to F

According to the ingredients and amounts shown in Table 1 below, the reactants and a catalyst were packed in an 8-liter reactor, which was equipped with a nitrogen tube, a stirrer, a catalyst inlet, a first-class output condenser, and A vacuum system. Based on the total weight of the reactants, dibutyltin dilaurate is used as a catalyst in an amount of 130 ppmw. Under a nitrogen atmosphere, the monocarbamate reaction was carried out at 70°C for 2 hours. Then, 4 kg of L-(or D-) lactide was supplied into the reactor, and then flushed with nitrogen five times.

Thereafter, the reaction mixture was heated to 150°C to completely dissolve the L-(or D-) lactide. Based on the total weight of the reactants, 120 ppmw of tin 2-ethylhexanoate catalyst was diluted with 500 ml of toluene, and the diluted solution was supplied into the reactor through the catalyst inlet. Under a pressure of 1 kg of nitrogen, the reaction was carried out at 185°C for 2 hours. Then, phosphoric acid was added to the reaction mixture in an amount of 200 ppmw through the catalyst inlet and mixed with it for 15 minutes to passivate the catalyst. After the catalyst is deactivated, vacuum conditions are applied until the pressure reaches 0.5 Torr to remove unreacted L-(or D-) lactide (about 5 wt% of the initial supply weight). The molecular weight, Tg, Tm, %C _bio, etc. of the obtained resin were measured and shown in Table 1.

Preparation Example 7: Preparation of polylactic acid resin G

As shown in Table 1 below, 865 g of HTPB 2.0 and 3.9 g of L-lactide and 0.1 kg of D-lactide are packed in an 8-liter reactor, which is equipped with a nitrogen tube, a stirrer, a The catalyst inlet, first-class effluent condenser, and a vacuum system were then flushed with nitrogen five times. Thereafter, the reaction mixture was heated to 150°C to completely dissolve the lactide. Based on the total weight of the reactants, 120 ppmw of tin 2-ethylhexanoate was diluted with 500 ml of toluene, and the diluted solution was supplied to the reactor through the catalyst inlet. Under a nitrogen pressure of 1 kg, the reaction was carried out at 185°C for 2 hours, and then phosphoric acid was added to the reaction mixture through the catalyst inlet in an amount of 200 ppmw and mixed with it for 15 minutes to passivate the catalyst. After the catalyst is deactivated, a vacuum condition is applied until the pressure reaches 0.5 Torr to remove unreacted L-lactide (about 5 wt% of the initial supply weight). Then, a dilution of HDI as shown in Table 1 and 120 ppmw of dibutyltin dilaurate catalyst in 500 ml of toluene was introduced into the reactor through the catalyst inlet. Under a nitrogen atmosphere, a polymerization reaction was carried out at 190°C for 1 hour, and the molecular weight, Tg, Tm, %C _bio, etc. of the obtained resin were measured and shown in Table 1.

Preparation Example 8: Preparation of polylactic acid resin H

In addition to using 885 grams of HTPB 2.0, 3.8 kilograms of L-lactide and 0.2 kilograms of D-lactide as shown in Table 1 below, HDI and D-L75 were introduced later, a polylactic acid resin system Prepared according to the same procedure as Example 7. The molecular weight, Tg, Tm, %C _bio, etc. of the obtained resin were measured and shown in Table 1.

Preparation Example 9: Preparation of polylactic acid resin I

As shown in Table 1 below, a polyol and 4 kg of L-lactide are packed in an 8-liter reactor, which is equipped with a nitrogen tube, a stirrer, a catalyst inlet, a first-class effluent condenser, and A vacuum system, followed by flushing with nitrogen five times. Thereafter, the reaction mixture was heated to 150°C to completely dissolve the lactide. Based on the total weight of the reactants, a 120 ppmw tin 2-ethylhexanoate catalyst was diluted with 500 ml of toluene, and the diluted solution was supplied to the reactor through the catalyst inlet. Under a nitrogen pressure of 1 kg, the reaction was carried out at 185°C for 2 hours, and then phosphoric acid was added to the reaction mixture at an amount of 200 ppmw through the catalyst inlet and mixed with it for 15 minutes to deactivate the catalyst. After the catalyst is deactivated, a vacuum condition is applied until the pressure reaches 0.5 Torr to remove unreacted L-lactide (about 5 wt% of the initial supply weight). The molecular weight, Tg, Tm, %C _bio, etc. of the obtained resin were measured and shown in Table 1.

Preparation Example 10: Preparation of Polylactic Acid Resin J

A polylactic acid resin was prepared according to the same procedure as Preparation Example 9, except that 6 grams of 1-dodecyl alcohol was used instead of polyol as shown in Table 1. The molecular weight, Tg, Tm, %C _bio, etc. of the obtained resin were measured and shown in Table 1.

Preparation Example 11: Preparation of polylactic acid resin K

As shown in Table 1 below, PBSA polyol (polyester polyol) and HDI are packed into an 8-liter reactor, which is equipped with a nitrogen tube, a stirrer, a catalyst inlet, and first-class effluent condensation Device, and a vacuum system, and then flushed with nitrogen five times. Based on the total weight of the reactants, dibutyltin dilaurate is used as a catalyst in an amount of 130 ppmw. Under a nitrogen atmosphere, the monocarbamate reaction was carried out at 190°C for 2 hours. Then, 4 kg of L-lactide was supplied into the reactor and completely dissolved in a nitrogen atmosphere at 190°C. An amount of 120ppmw as an addition polymerization catalyst of tin 2-ethylhexanoate and an amount of 1,000 as a monoester and/or ester amide exchange catalyst of dibutyltin dilaurate are introduced through the catalyst inlet, and at 500 Dilute in ml of toluene. Under a pressure of 1 kg of nitrogen, the reaction was carried out at 190°C for 2 hours, and then phosphoric acid was added to the reaction mixture through the catalyst inlet in an amount of 200 ppmw and mixed with it for 15 minutes to passivate the catalyst. After the catalyst is deactivated, a vacuum condition is applied until the pressure reaches 0.5 Torr to remove unreacted L-lactide (about 5 wt% of the initial supply weight). The molecular weight, Tg, Tm, %C _bio, etc. of the obtained resin were measured and shown in Table 1.

Examples 1 to 8 and Comparative Examples 1 to 8: Preparation of molded products

The polylactic acid resins prepared in Preparation Examples 1 to 11 were dried under reduced vacuum at 1 Torr, dried at 80°C for 6 hours, and in a super mixer with the polypropylene and polypropylene shown in Tables 2 and 3 below Mix with other materials. The mixture thus obtained is extruded at 200 to 230°C with a 19-mm twin screw extruder (in addition, such as a single screw extruder, a roll mill, a kneader, or a Banbury mixer) Various known equipment can be used) kneading and extruding into a strand type. The strands thus formed are cooled in a water bath and cut into pellets with a granulator. The pellets thus prepared were dried in a hot air dryer at 80°C for 4 hours, and subjected to injection molding to obtain film samples. Membrane samples were evaluated, and the results are shown in Tables 2 and 3.

Experimental example

The molecular weight distribution, Tg, Tm, %C _bio, etc. of the resins prepared in Preparation Examples 1 to 11 were evaluated as follows, and the results are shown in Table 1.

(1) NCO/OH: isocyanate group of diisocyanate compound (for example, hexamethylene diisocyanate) used in the reaction to form a polyolefin-based polyol repeating unit/polyether-based polyvalent Molar ratio of terminal hydroxyl groups of alcohol repeating units (or (co)polymers).

(2) OHV (KOH mg/g): By dissolving the polyol repeating unit (or (co)polymer) based on polyolefin in dichloromethane, the repeating unit is acetylated to make the acetylene The hydrolyzed repeating unit is hydrolyzed to produce acetic acid and measured by titrating acetic acid with 0.1 N KOH in methanol. It corresponds to the number of terminal hydroxyl groups of the polyol repeating unit (or (co)polymer) dominated by polyolefin.

(3) Mw and Mn (g/mol) and molecular weight distribution (Mw/Mn, MWD): by subjecting a 0.25% by weight polylactic acid resin solution in chloroform to gel permeation chromatography (by Viscotek TDA 305 Manufacture, column: Shodex LF804*2 ea.). Polystyrene is used as a standard material to determine the weight average molecular weight (Mw) and number average molecular weight (Mn). The molecular weight distribution (MWD) is calculated from Mw and Mn.

(4) Tg (glass transition temperature, °C): When quenching a molten sample and then increasing the sample temperature at a rate of 10 °C/min, it was measured with a differential scanning calorimeter (manufactured by TA Instruments). Tg is determined by the middle value of an endothermic curve and a tangent line of the baseline.

(5) Tm (melting temperature, °C): When quenching a molten sample, and then increasing the sample temperature at a rate of 10 °C/min, the volume is measured with a differential scanning calorimeter (manufactured by TA Instruments). Tm is determined from the maximum value of the melting endothermic peak of the crystal.

(6) Residual monomer (lactide) content (wt%): by dissolving 0.1 g of resin in 4 ml of chloroform, adding 10 ml of hexane, and filtering the resulting mixture, followed by GC analysis And measure.

(7) The content of polyolefin-based polyol repeating units (% by weight): The content of polyolefin-based polyol repeating units in the prepared polylactic acid resin is a 600 MHz nuclear magnetic resonance (NMR) Spectrometer measurement.

(8) Sheet color-b: The color of the resin sheet-b value is measured by using a color difference meter CR-410 manufactured by Konica Minolta Sensing Co., and is expressed as the average of five measurements.

(9) Organic carbon content (%C _bio ) of biomass-based carbon: According to ASTM D6866, a test measurement for measuring the content of biomass-based materials from organic modern carbon (percent modern; ¹⁴ C)

(10) IV (dl/g): inherent viscosity

Meanwhile, the physical properties of the films prepared in Examples 1 to 8 and Comparative Examples 1 to 8 were evaluated as follows, and the results are shown in Tables 2 and 3.

(1) Extrudability: Polylactic acid-polyolefin alloy resin is extruded into a strand type at 200 to 250°C with a 30-mm twin-screw extruder equipped with a hole die, and the extruded strand Cured in a water bath at 20°C. At this time, the melt viscosity and uniformity of the extrudate were visually observed. The melt viscosity uniformity condition (extrusion) is evaluated according to the following criteria:

◎: Due to the good compatibility and uniform melt viscosity between the two resins, the strands are easily prepared without cracking:

○: Due to the low compatibility and low melt viscosity uniformity between the two resins, the strands were prepared with some cracks; and

x: Due to the extremely low compatibility between the two resins and the poor uniformity of the melt viscosity, the strands are prepared by cracking and die expansion.

(2) Melt index (MI): measured at 210°C, 2.16 kgf according to ASTM D1238, and indicated by the average of three measurements.

(3) Compatibility: Polylactic acid resin Polylactic acid-polyolefin alloy resin is extruded at 200 to 250 ℃ using a 30-mm twin screw extruder equipped with a hole die, and the extrudate is at 20 ℃ Cured in water bath to obtain a strand sample. The strand sample is immersed in liquid nitrogen and cut. The cut surface was observed using a scanning electron microscope (SEM) and evaluated according to the following criteria:

◎: The two resins are well dispersed, and the particle size of the undispersed resin is 0.2 μm or less;

○: The two resins are still dispersible, and the particle size of the undispersed resin is 1.0 μm or less; and

x: The dispersion of the difference between the two resins, and the particle size of the undispersed resin is 1.0 μm or more.

(4) Appearance: as follows, the appearance of the sample is visually inspected for flow marks, weld lines and reduced gloss due to reduced fluidity:

◎: No flow marks and weld lines due to good melt viscosity, and good surface gloss;

○: Due to the slightly high melt viscosity, there are no flow marks and weld lines, but the gloss is reduced; and

x: Flow marks, weld lines, and gloss reduction due to extremely high melt viscosity.

(5) Initial tensile strength (kgf/cm ² ): A sample was prepared according to ASTM D638, and adjusted at a temperature of 20°C and a humidity of 65% RH for 24 hours. The initial tensile strength was measured using a Universal testing machine (UTM, manufactured by INSTRON) and indicated by the average of five measurements.

(6) Elongation (%): Under the same conditions as the initial tensile strength of (5) above, it is determined when the sample breaks. The average of five measurements is provided.

(7) Impact strength (kgf-cm/cm): Use an Izod impact tester according to ASTM D256.

(8) Flexural strength (kgf/cm ² ) and flexural modulus (kgf/cm ² ): A test sample was prepared according to ASTM D790, and the flexural strength and flexural modulus were measured using UTM (INSTRON). The average of five measurements is provided.

(9) Heat resistance (°C): A test sample is prepared according to ASTM D648, and the heat resistance of the sample is tested using UMT.

i) High temperature mold: a high temperature mold is used at 110°C, and the cooling time is about 30 seconds.

ii) Low temperature mold: a low temperature mold is used at room temperature, and the cooling time is about 30 seconds.

(10) Outflow: Observe the surface of the molded product, and the outflow of the low molecular weight plasticizer on the surface of the film is evaluated on the A4 size film sample according to the following criteria by touch:

◎: No outflow;

○: outflow, but not serious; and

x: Severe outflow.

(11) Tensile strength retention rate (%): A film sample with a length of 150 mm and a width of 10 mm was prepared and adjusted at a temperature of 40°C and a humidity of 90% RH for 30 days. The tensile strength is measured and compared with the initial tensile strength value.

(12) Malodor: High-volatility malodor from the extruded mixture after the mixing method was checked:

◎: Bad smell detected

x: No bad smell detected

(13) Total volatile organic compounds (TVOC): headspace-GC/MS analysis

1) 2 g of sample is placed in a sealed bottle and subjected to HS-GC/MS

2) STD: A series of 250, 500 and 1000 ppm toluene standard solutions (50 μL) were prepared and sealed in a bottle, and subjected to HS-GC/MS analysis

3) HS-GC/MS

-HS: Heating at 180°C (30 minutes), and performing headspace gas analysis

-Column DB-5 (60m×0.32mm×1.0μm)

-80℃(5 minutes)-10℃/min-320℃(16 minutes), injection at 280℃, 1:30 split

Referring to Table 2, Examples 1 to 5 and 7 to 8 represent molded products prepared from a polylactic acid-polyol ether alloy resin composition, and these resin compositions contain a soft amount of 5 to 35% by weight in the polylactic acid resin The segment (polyol-based polyol repeating unit) has a low color-b value, contains an appropriate amount of antioxidant, has a weight average molecular weight of 100,000 to 400,000 and a molecular weight distribution of 1.60 to 3.0, 20 to 60 Tg at ℃, and Tm at 145 to 178 ℃. Furthermore, Example 6 shows a molded product prepared from a polylactic acid-polyether alloy resin composition including a conventional polylactic acid resin (Resin J) and a polylactic acid resin (Resin F) of the present invention.

The molded products of Examples 1 to 8 exhibit excellent mechanical properties, such as an initial tensile strength of 200 kgf/cm ² or more, and an impact strength of 5 kgf-cm/cm or more, and exhibit 100°C or more The great heat resistance expressed by the high temperature mold HDT. Furthermore, when the sample is adjusted at a temperature of 40°C and a humidity of 90% RH for 30 days, the molded product has a retention rate of tensile strength of 80% or more due to the absence of styrene or acrylic compatibilizer and plasticization The agent has a TVOC of 100 ppm or less, and there is no outflow. Therefore, it can effectively reduce the total volatile organic compounds harmful to the human body. In addition, because of having a total biomass content of 25% or more, these molded products are considered to be environmentally friendly materials.

In contrast, the molded product of Comparative Example 1 prepared from a polylactic acid-polyolefin alloy resin containing one of the conventional polylactic acid resins A showed good general properties, but the sample had a total biomass content of less than 25%. Therefore, It cannot meet the standards of the Global Standard for environmentally friendly plastics. Furthermore, the molded product of Comparative Example 2 prepared from a polylactic acid-polyolefin alloy resin composition containing one of the traditional polylactic acid resins J lacks compatibility between the polylactic acid resin and the polypropylene resin, and among these resins There is a large difference in the melt viscosity between the two; therefore, the final product is not suitable as a molded product because it has poor extrudability, the mold is expanded when the molten composition is discharged, and the tensile strength is less than 200kgf/cm ² , Less than 5kgf-cm/cm impact strength, and poor moisture resistance. Furthermore, in the case of the molded products of Comparative Examples 3 and 4 prepared from the polylactic acid-polyolefin alloy resin composition containing one of the polylactic acid resin J combined with a compatibilizer, the compatibilizer was introduced and extruded. The properties are good, but the compatibility between the two resins is insufficient to give the final molded product satisfactory general mechanical properties, moisture resistance, or heat resistance. Furthermore, the use of compatibilizers causes severe malodor and run-off problems.

In the case of the molded product of Comparative Example 5 prepared from a polylactic acid-polyolefin alloy resin composition containing either polylactic acid resins J and I, the extrudability is poor and the final product has a poor appearance because of the two resins The difference in melt viscosity is too large, and the compatibility is poor. In addition, the molded products have unsatisfactory general mechanical properties, moisture resistance, and heat resistance.

In addition, Comparative Examples 6 and 7 represent preparations by simply mixing and kneading a polylactic acid resin J and an aliphatic polyester polyol, and then subjecting the thus obtained mixture to injection molding. This aliphatic polyester polyol By polycondensation reaction of poly(1,3-propanediol) having a number average molecular weight of 2,400, 1,4-butanediol having a number average molecular weight of 11,000, succinic acid, and adipic acid as a plasticizer In the preparation, the polylactic acid resin does not contain a polyol repeating unit (soft segment) mainly composed of polyolefin. Due to the unsatisfactory dispersibility of the plasticizer between these resins, the molded products of Comparative Examples 6 and 7 have high turbidity, poor extrudability, and appearance. Furthermore, after a period of time has elapsed, the plasticizer flows out of the molded product, and the molded product has poor moisture resistance and TVOC properties.

Furthermore, the molded product of Comparative Example 8 was prepared from a polylactic acid-polyolefin alloy resin containing a polylactic acid resin having a broad molecular weight distribution together with a polyester polyol repeating unit. Because the molded product of Comparative Example 8 has a polyurethane which is randomly attracted as a softening component in a small-segment type, it exhibits relatively good efflux resistance and TVOC properties. However, due to the relatively small size polylactic acid repeating unit, the molded product exhibits poor heat resistance (such as low Tm), and also has poor mechanical properties due to compatibility issues. Furthermore, due to the poor compatibility between the polyhydric alcohol used to form the softening component and the polylactic acid, the molded product has high turbidity and low transparency. Due to the ester and/or amide exchange reaction that occurs during resin preparation, a broad molecular weight distribution is observed, resulting in uneven melting properties, poor film extrudability, mechanical properties, and moisture resistance.

Meanwhile, the pellets prepared in Examples 1 to 3 and Comparative Examples 2 and 4 were observed using a scanning electron microscope, and the results are individually illustrated in FIGS. 1 to 5. 1 to 5, the white part represents a polylactic acid resin, and the black part represents a polypropylene resin.

Compared with Figs. 4 and 5, in Figs. 1 to 3, regardless of the ratio of polylactic acid resin to polypropylene resin, it can be seen that there is no clear difference between the white part of polylactic acid resin and the black part of polypropylene resin. This indicates that the compatibility between the two resins is enhanced without a special compatibilizer, which also indicates improved flexural modulus and impact strength. In particular, it can be summarized that these pellets have improved compatibility compared to FIG. 5 using a compatibilizer.

In summary, the polylactic acid resin or polypropylene resin of the polylactic acid resin-polyolefin alloy resin composition improves the dispersibility of polypropylene or polypropylene resin. This improvement is known as a disadvantage of polylactic acid resin, such as heat resistance. , Crystallization rate, and impact resistance, thus balancing the overall properties of the resin composition.

Claims (16)

A polylactic acid-polyolefin alloy resin composition, comprising: (1) 30 to 90 parts by weight of a polylactic acid resin and (2) 70 to 10 parts by weight of a polyolefin-based resin, wherein the polylactic acid resin (1) contains a hard segment, which contains a A polylactic acid repeating unit having the chemical formula 1; and a soft segment comprising a polyolefin-based polyol repeating unit, wherein the polyolefin-based polyol structural unit having the chemical formula 2 is passed through an amine The carbamate bond or an ester bond is connected in a linear or branched manner, wherein the organic carbon content (%C _bio ) of the biomass-based carbon as defined in Equation 1 is at least 60% by weight, and wherein, Chemical formulas 1 and 2, n is an integer from 700 to 5,000, and m+1 is an integer from 5 to 200:

[Equation 1] %C _bio = (weight ratio of ¹⁴ C isotope to ¹² C weight of total carbon content in the polylactic acid resin)/( ¹⁴ C isotope pair of total carbon content in carbon standard materials based on biomass ¹² C weight ratio). The polylactic acid-polyolefin alloy resin composition according to claim 1, based on the total of 100 parts by weight of the polylactic acid resin (1) and the polyolefin-based resin (2), further comprising 0.1 to 20 parts by weight One part impact modifier. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the content of the ¹⁴ C isotope is 7.2 x 10 ^-11 to 1.2 x 10 ^-10 based on the total weight of carbon in the polylactic acid resin %. The polylactic acid-polyolefin alloy resin composition of claim 1, wherein the soft segment has an organic carbon content (%C _bio ) of at least 70% by weight of biomass-based carbon as defined in Equation 1. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the polylactic acid resin has a number average molecular weight of 50,000 to 200,000, and a weight average molecular weight of 100,000 to 400,000. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the polylactic acid resin has a glass transition temperature (Tg) of 20 to 55°C, and a melting temperature (Tm) of 145 to 178°C. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the urethane bond is formed by the polyolefin-based polyol structural unit or by the polyolefin-based polyol The terminal hydroxyl group of the prepolymer prepared by the addition polymerization reaction between the terminal hydroxyl group of the structural unit and the lactide is formed by the reaction with a diisocyanate or a di- or higher-functionality isocyanate compound. The polylactic acid-polyolefin alloy resin composition of claim 1, wherein the polylactic acid resin includes a terminal carboxyl group of the polylactic acid repeating units contained in the hard segment via an ester bond The block copolymers of the terminal hydroxyl groups of the polyol structural units containing polyolefin as the main component contained in the soft segment, or one of the block copolymers through a urethane bond A linear or branched block copolymer. The polylactic acid-polyolefin alloy resin composition according to claim 8, wherein the polylactic acid resin further comprises a polylactic acid homopolymer which remains uncoupled from the polyol repeating unit mainly composed of polyolefin. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the polymer of the polyol repeating unit mainly composed of polyolefin has a number average molecular weight of 1,000 to 100,000. The polylactic acid-polyolefin alloy resin composition according to claim 8, wherein the terminal hydroxyl group of the polyol structural unit mainly composed of polyolefin is the diisocyanate or the di- or higher-functionality isocyanate compound. The molar ratio of isocyanate groups ranges from 1:0.50 to 1:0.99. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the polylactic acid resin contains the hard segment in an amount of 65 to 95 parts by weight per 100 parts by weight of the polylactic acid resin, and 5 to 35 The weight of the soft segment. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the polyolefin resin is a propylene homopolymer, or one selected from propylene and at least one selected from ethylene, 1-butene, 4-methyl-1 -Copolymers made from olefins consisting of pentene, 1-hexene, and 1-octene. The polylactic acid-polyolefin alloy resin composition according to claim 1, wherein the polyolefin resin is a highly crystalline polyolefin resin, and when determined by the xylene solubles (Xs) test, the polyolefin resin has 12 % Or less polypropylene random part. The polylactic acid-polyolefin alloy resin composition according to claim 1, which has a color-b value of less than 10. The polylactic acid-polyolefin alloy resin composition according to claim 1 contains residual monomer in an amount of less than 1% by weight based on the total weight of the polylactic acid resin.

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