TWI706989B - 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 (%C_bio) 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 Invention field

The invention relates to a polylactic acid-polyolefin alloy resin composition. More particularly, the present invention relates to an alloy resin composition comprising a polylactic acid resin and a polyolefin with environmentally friendly properties, which is due to improved heat resistance and excellent general properties such as impact resistance and resistance Wetness, 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 now widely used 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 gradual exhaustion of petroleum sources, the use of biomass-based resins (typically polylactic acid resins) is widely considered as an alternative.

However, compared with petroleum-based resins, polylactic acid resins have unsatisfactory heat resistance and moisture resistance or mechanical properties; therefore, they The 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 the poor flexibility of polylactic acid resins.

To overcome the limitation of polylactic acid resin, polylactic acid resin and other The alloy composition of general resin and/or engineering plastic has been used. Although molded products containing polylactic acid resin have been prepared from these alloy compositions, due to the incompatibility between the two resins, the improvement of heat resistance and mechanical properties is limited in most cases.

Furthermore, in order to overcome the above-mentioned problems, it has recently been proposed to form a polylactic acid Adding a graft copolymer compatibilizer during the process of an alloy of acid resin and a polyolefin-based resin (Korean Patent No. 1182936 and Korean Early Publication Patent Publication No. 2012-0128732 and 2012-0117130 ). However, the resin composition based on polylactic acid and the product prepared by using this graft copolymer compatibilizer or a glycidyl methacrylate reaction compatibilizer have the disadvantage of high cost. Furthermore, since it overcomes the limitation of low compatibility between polylactic acid resin and polyolefin-based resin, 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 (TVOC) 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 alkyl compounds having 5 to 12 carbon atoms The substance releases a strong stimulating taste. When people are exposed to air containing these volatile organic compounds for a long time, they will suffer from headache, drowsiness, nausea, difficulty breathing, eyes, nose, sore throat, etc.

Furthermore, due to the hydrolysis reaction caused by other water Lactic acid resins are 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 are in one molding It evaporates during the process and will cause equipment pollution or corrosion, or deteriorate the nature of the finished product. In particular, in the case of sheet production through extrusion molding, the remaining lactic acid monomers and oligomers volatilize during the sheet extrusion process, thus causing thickness changes. In the case of sheet manufacturing through 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, thus causing its mechanical properties to deteriorate. In addition, because polylactic acid resins can easily absorb water by nature, water can be easily absorbed during a cooling method in a water bath after extrusion, or when a kneaded product is stored in the form of pellets. When these pellets are injection molded, due to the water contained in the pellets, the product will have a poor appearance, such as a silver streak, and deteriorated physical properties.

Therefore, there is a continuing need for an improved heat resistance and moisture resistance A polylactic acid resin composition with excellent general properties (such as mechanical properties, impact resistance or flow resistance), and a polylactic acid resin composition that can reduce the total volatile organic compounds generated from the resin after a mixing method while maintaining polylactic acid Technology with unique characteristics of resin.

Summary of the invention

Therefore, one object of the present invention is to provide a polylactic acid-polyolefin alloy resin composition with environmentally friendly properties, which is 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, there is provided a polylactic acid-polyolefin alloy resin composition, comprising: (1) 30 to 90 parts by weight of polylactic acid resin and (2) 70 to 10 parts by weight of polyolefin as the main component The resin, wherein the polylactic acid resin (1) includes a hard segment, which includes a polylactic acid repeating unit of formula 1; and a soft segment, which includes a polyolefin-based polyol repeating unit, wherein , The polyolefin-based polyol structural unit with chemical formula 2 is connected in a linear or branched manner via a urethane bond or an ester bond, where the biomass-based carbon as defined in Equation 1 The organic carbon content (%C _bio ) is at least 60% by weight, and in the 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 = (14}} C isotopes of the total carbon content of the polylactic acid resin in a weight ratio of ¹² C in) ¹⁴ C isotope content of the total carbon / (carbon in the biomass-based material of ¹² standard 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 has a significant contribution to avoiding environmental pollution due to its environmentally friendly nature.

Brief description of schema

When combined with the drawings, the above and other objects and features of the present invention will become apparent from the following descriptions of the present invention, which are shown in the following figures: Figures 1 to 3: Scanning electrons of the pellets prepared in Examples 1 to 3 Microscope (SEM) photographs, and Figures 4 and 5: exemplified the SEM photographs of the pellets prepared in Comparative Examples 2 and 4.

Detailed description of the invention

Thereafter, according to one embodiment of the present invention, polylactic acid-polyolefin The alloy resin composition is 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) includes a hard segment, which includes a polylactic acid repeating unit of Chemical Formula 1; and a soft segment, which includes a polyolefin-based polyol repeating unit, wherein the polylactic acid repeating unit of Chemical Formula 2 The olefin-based polyol structural units are connected in a linear or branched manner via a urethane 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 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 = (14}} C isotopes of the total carbon content of the polylactic acid resin in a weight ratio of ¹² C in) ¹⁴ C isotope content of the total carbon / (carbon in the biomass-based material of ¹² standard 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 contains a polyolefin-based polyol repeating unit as a soft segment. Here, the polyolefin-based polyol repeating unit, and the polyolefin-based polyol structural unit represented by Chemical Formula 2 is through a urethane 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 the polylactic acid repeating unit as a hard segment, the polylactic acid resin exhibits environmentally friendly properties and biodegradable properties, which is unique to resins based on biomass. In addition, according to the experimental data obtained by the inventors of the present case, it is confirmed that the polylactic acid resin exhibits improved flexibility (for example, relatively low Young's modulus measured in the longitudinal and transverse directions), and because polyolefin is used 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 combined hard and soft segments, the polylactic acid resin reduces the possibility of decreased stability or soft segments (which are the cause of flexibility) flowing out. A film containing this polylactic acid resin is less likely to suffer from high haze or low transparency. Furthermore, this polylactic acid resin can exhibit the aforementioned benefits without using a large amount of soft segments (which are the cause of flexibility); therefore, it can contain a relatively large amount of a resin based on biomass, for example, 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, compared with the traditional polylactic acid resin, has excellent moisture resistance.

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 polyolefin-based polyol repeating units, when a polyester-based repeating unit is used as a soft segment, it is difficult to obtain about The 60% by weight organic carbon content (%C _bio ) is due to the need to use a large amount of other resins, such as a polyester-based polyol repeating unit derived from a petroleum-based source.

The measurement of the organic carbon content (%C _bio ) of the biomass-based carbon expressed in Equation 1 can be implemented 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 biomass-based carbon will be explained in detail.

Generally, unlike organic materials derived from petroleum-based resins, organic materials derived from biomass-based (or living sources) resins 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 wt%), ¹³ C (about 1.108 wt%), 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 metabolism in living organisms with the environment.

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 in the initial stage, n is the number of ¹⁴ C atoms remaining after time t, and a is the decay constant (or radioactive decay constant), which is related to the half-life.

In Equation 2, the half-life of ¹⁴ C is approximately 5,730 years. Considering this pungent life, organic materials derived from living organisms that continuously interact with its surrounding environment, that is, resins based on biomass (mainly from living sources), can substantially maintain a fixed amount of ¹⁴ C and a fixed isotope The content ratio, for example, the 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 oil 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 contain substantially no ¹⁴ C isotope.

Equation 1 is based on the technical significance described above. In Equation 1, the denominator can be the weight ratio of ¹⁴ C/ ¹² C in biomass-based carbon, for example, about 1.2 x 10 ^-12 , and the numerator can 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 living substances is maintained at about 1.2 x 10 ^-12 , and the weight ratio of carbon atom isotopes derived from fossil fuels is substantially zero, the 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 determining the biological content of natural range materials using radiocarbon and isotope ratio mass spectrometry analysis) measuring. Preferably, the measurement can be performed by mass spectrometry, in which 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 technology, 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 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 can be Contains a larger amount of biomass-based resin and carbon, so it can enhance environmentally friendly properties and biodegradability.

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

Biochemical products such as polylactic acid resin are biodegradable and release less carbon dioxide. Compared with petrochemical products, according to the current level of technology, the content of carbon dioxide released can be reduced by up to 108%, and the energy required to make resin can be saved by up to 50%. In addition, when biomaterials are used to make a bioplastic instead of fossil fuels, the CO ₂ emissions calculated by ISO 14000-compliant life cycle analysis (LCA, Life Cycle Assessment Program) can be reduced by up to about 70%.

As a special example, according to NatureWotks, when 1 kg of PET resin is manufactured, 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 approximately 77% CO ₂ reduction. Furthermore, in terms of energy consumption, compared with the energy consumption of PET, this bioplastic only needs 56% of the energy. However, conventional polylactic acid resins have limitations due to their low flexibility, and it has been observed that when other ingredients such as plasticizers are used to correct this problem, the advantages of the bioplastics as described above will be significantly impaired.

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

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

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

In the polylactic acid resin, the polylactic acid repeating unit of the hard segment can be derived from biomaterials, and the polyolefin structural unit of the soft segment can also be derived from biomaterials. The polylactic acid structural unit can be obtained, for example, from a polyolefin-based polyol resin, which is derived from a biomaterial. The biomass can be any plant or animal source, for example, a plant source such as corn, sugar cane or cassava. Thereby, the polylactic acid resin containing polyolefin-based polyol structural units derived from biomaterials and the polylactic acid-polyolefin alloy resin composition containing this 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 the biomaterial has at least about 90% by weight, preferably about 95 to 100% by weight, the organic carbon content (%C _bio ) as defined in Equation 1; and is derived from the biomaterial The soft segment has at least about 70% by weight, preferably about 75 to 95% by weight of the organic carbon content (%C _bio ) as defined in Equation 1.

The polylactic acid-polyolefin alloy resin composition containing biomass-based polylactic acid resin has at least about 60% by weight, or at least about 80% by weight, high organic carbon content (%C _bio ), therefore, it meets the criteria used to obtain the "Biomass Pla" classification of JBPA (classification based on the standard ASTM D6866). Therefore, polylactic acid resin can properly bear the label of "Biomass-based" by JORA.

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

At the same time, polyolefin contained in the soft segment of polylactic acid resin The main polyol repeating unit has a structure, wherein the polyolefin-based polyol structural unit with chemical formula 2 is through a urethane bond (-C(=O)-NH-) or a ester The bond (-C(=O)-O-) is connected in a linear or branched manner. In particular, polyolefin-based polyol structural units may refer to polymers prepared from monomers such as butadiene (for example, poly1,2-butadiene or poly1,3-butadiene), or One of the structural units of this polymer is a liquid phase hydroxyl-terminated polybutadiene (HTPB) with a number average molecular weight of 1,000 to 5,000 prepared from a hydrogenation reaction, which may have a hydroxyl group at its terminal.

Polyol structural unit based on polyolefin or by polyolefin Between the terminal hydroxyl group of the hydrocarbon-based polyol structural unit and lactide The terminal hydroxyl groups of the prepolymer prepared by the addition polymerization reaction can react with diisocyanate or di- or higher-functional isocyanate compounds to form a urethane bond. At the same time, the terminal hydroxyl group of the polyolefin-based polyol structural unit can react with lactide or a lactic acid derivative compound to form an ester bond (-C(=O)-O-). The polyolefin-based polyol structural unit is connected in a linear or branched manner via the urethane or ester bond to form a polyolefin-based polyol repeating unit.

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

Among them, the polyolefin-based polyol structural unit is through a The urethane bond is linearly connected to a polymer, or a repeating unit of the polymer, which can be called a polyurethane polyol repeating unit, and may have a hydroxyl group at the terminal. Therefore, polyol repeating units based on polyolefins can be used as initiators for the formation of polylactic acid repeating units in the polymerization process. When the molar ratio of terminal hydroxyl group: isocyanate group exceeds 0.99, the number of terminal hydroxyl groups in the repeating unit of polyurethane polyol is insufficient (OHV<1); therefore, it cannot be suitably used as a starting point Agent. Furthermore, when the molar ratio of hydroxyl group: isocyanate group is too low, the terminal hydroxyl group of the polyolefin-based polyol repeating unit becomes too excessive (OHV>35); therefore, it is difficult to obtain high molecular weight Polylactic acid repeat list Yuan and polylactic acid resin.

Polymer with polyol repeating unit based on polyolefin It 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 polyolefin-based polyol repeating units 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 an attractive effect. 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 deterioration of the film's flexibility, moisture resistance, and mechanical properties.

The diisocyanate compound may have at least two isocyanates Any compound of the group, as long as it forms a urethane bond with the terminal hydroxyl group of the polyolefin-based polyol repeating unit: it can be derived from fossil fuels.

Examples of diisocyanate compounds include 1,6-hexamethylene bis Isocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate Isocyanate, 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 the hexamethylene diisocyanate compound. Isocyanate isotrimerization Cyanate esters, triisocyanate compounds, and these isomers are composed of groups. 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.

At the same time, the polylactic acid resin contained in the composition may contain a The terminal carboxyl group of the polylactic acid repeating unit contained in the hard segment is connected to the terminal hydroxyl group of the polyolefin-based polyol structural unit contained in the soft segment via an ester bond. Block copolymer, or a block copolymer in which the block copolymer is connected in a linear or branched manner via a urethane bond.

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

[Formula 2] Polylactic acid repeating unit (L)-(E)-polyolefin-based polyol structural unit (O)-(E)-polylactic acid repeating unit (L)-(U)-polylactic acid repeating unit Unit (L)-(E)-polyolefin-based polyol structural unit (O)-(E)-polylactic acid repeating unit (L), where O refers to polyolefin-based polyol structural unit , U refers to a urethane bond, and E refers to an ester bond.

Because polylactic acid resin contains a polylactic acid repeating unit and A block copolymer in which polyolefin-based polyol structures or repeating units are connected together, which inhibits the outflow of polyolefin-based polyol structures or repeating units that cause flexibility. Therefore, the resulting film may have excellent moisture resistance, transparency, mechanical properties, heat resistance, or blocking resistance. In addition, because at least some polylactic acid structures or repeating units and polyolefin-based polyol repeating units 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, and heat resistance of the film produced therefrom can be improved.

But it is not necessary to make all the polylactic acid contained in the polylactic acid resin The repeating unit is connected with a polyolefin-based polyol structure or repeating unit to form a block copolymer. At least some of the polylactic acid repeating units may be a polylactic acid homopolymer that is not combined with polyolefin-based polyol structures or repeating units. In this case, the polylactic acid resin can be a mixture comprising: a terminal carboxyl group of the polylactic acid repeating unit contained in the hard segment is connected to the polyolefin contained in the soft segment via an ester bond. A block copolymer in which the terminal hydroxyl groups of the main polyol structural unit are connected, a block copolymer prepared by connecting the block copolymer in a linear or branched manner through a urethane bond, And a polylactic acid homopolymer that remains uncoupled with polyolefin-based polyol repeating units.

At the same time, with 100 parts by weight of total polylactic acid resin (when polylactic acid When the polymer is selectively included, based on 100 parts by weight of the total weight of the block copolymer and homopolymer), the polylactic acid resin may contain about 65 to 95 parts by weight, about 80 to 95 parts by weight, or about 82 to 92 parts by weight of the hard segment; and about 5 to 35 parts by weight, about 5 to 20 parts by weight, or about 8 to 18 parts by weight of the soft segment.

If the amount of the soft segment is 35 parts by weight or less, a polymer An amount of polylactic acid resin can be provided, and its mechanical properties (for example, the strength of the film, etc.) can be enhanced. In addition, the transport properties, processability, or dimensional stability of the film can be improved during the packaging process. 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 mainly composed of polyolefin in the soft segment can be used as a co-agent, thus avoiding the reduction of polymerization conversion rate and forming a high molecular weight polylactic acid resin.

Polylactic acid resin in polylactic acid-polyolefin alloy resin composition It 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 will affect 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 a melting method such as extrusion, and therefore, 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 about 1.60 to 3.0, preferably about 1. The molecular weight distribution (Mw/Mn) from 80 to 2.15 is defined by the ratio of the weight average molecular weight (Mw) to the number 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 melting methods such as extrusion, so that it can be effectively processed and extruded into a film, and the film containing the polylactic acid resin Shows 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, mechanical properties such as film strength will be reduced, and its melting properties will deteriorate, for example, resulting in too low melt viscosity, therefore, it will become difficult to extrude the composition into a film, or to form a film Will be in poor extrusion conditions.

Furthermore, the polylactic acid resin may have a temperature of about 145 to 178°C, preferably The melting temperature (Tm) is 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, polylactic acid resin, for example, the block copolymer contained therein It 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 including the resin composition can have optimized flexibility and stiffness, and therefore 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 therefrom exhibits suitable stiffness, and therefore can have good transport properties during packaging methods using this film, and Processability, dimensional stability, or resistance to caking. Furthermore, if the film has a glass transition temperature of about 55°C or less, the film exhibits good flexibility and improved adhesion strength at the adhesion interface with the target object to be wrapped, and due to reduced noise, the film can be used as a wrap.

Meanwhile, the polylactic acid-polyolefin alloy resin composition may contain every The part by weight of the polylactic acid resin contained therein is less than about 1% by weight, preferably about 0.01 to 0.5% by weight of residual monomers (for example, lactide monomers used to form polylactic acid repeat units ). Because the polylactic acid-polyolefin alloy resin composition contains a block copolymer with a special structural feature and a polylactic acid resin containing this block copolymer, and selective antioxidants, 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 residual monomers (for example, residual lactide monomers, etc.) to a minimum.

If the content of residual monomers is less than 1% by weight, odor problems The film forming method using the polylactic acid-polyolefin alloy resin composition does not occur, and the protection increases the strength of the final film, because the polylactic acid resin has a suitable molecular weight, and the film can be suitably used for food packaging.

(2) Polyolefin resin

According to one aspect of the present invention, the polyolefin resin contained in the polylactic acid-polyolefin alloy resin composition 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, and heat resistance.

The polyolefin resin may be a homopolymer of propylene, or a copolymer formed from propylene and aliphatic α -olefins and/or aromatic olefins having 2 to 20 carbon atoms (except 3 carbon atoms), preferably propylene Homopolymers or copolymers formed from propylene and aliphatic α -olefins and aromatic olefins with 2 to 8 carbon atoms (except 3 carbon atoms), more preferably propylene homopolymers or from propylene and at least one Copolymer prepared from olefins composed 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 can be a highly crystalline polyolefin resin, for example, A homogeneous polypropylene with high crystallinity, a block polypropylene with high crystallinity, a random polypropylene with high crystallinity, etc.

Highly crystalline polyolefin resin may have 150°C or greater, preferably It is a melting temperature of 165 to 170°C, a crystallization temperature of 120°C or more, preferably a crystallization temperature of 124 to 130°C, and a heat distortion temperature of 120°C or more, preferably 130 to 140°C.

Furthermore, the highly crystalline polyolefin resin may have 5 to 100 g/10 Minutes (230°C, 2.16 kg), preferably 10 to 50 grams/10 minutes, more preferably 20 to 40 grams/10 minutes melt index (ASTM D1238). When the melt index is in this range, the resin has good compatibility with polylactic acid resin, has 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 greater, or this And other mixtures.

Polyolefin resin can have a weight average of 100,000 to 700,000 Molecular weight.

The polyolefin resin may have a flexural modulus of 14,000 kg/ ^cm2 or more, preferably 15,000 to 19,000 kg/ ^cm2 .

Furthermore, when judged by the xylene solubles (Xs) test, polyolefin The hydrocarbon resin is preferably a highly crystalline polyolefin resin having 12% or less of polypropylene random part, more preferably a highly crystalline polyolefin having 5% or less of polypropylene random part Resin. Xs test is a method used to measure random parts according to ASTM D5492 (or ISO 16152). According to this method, a polypropylene resin is completely soluble in xylene to precipitate the 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, polypropylene resin can have a conformity index (II) of 95% or greater. When II is in this range, the resin composition can have excellent heat resistance, impact resistance, and scratch resistance. The C ¹³ NMR spectroscopy technique 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 pentane meso component ratio is the fraction of propylene monomer units present in one chain, in which five propylene monomer units are continuously meso-bonded. If the meso pentad component ratio is high, the propylene resin has high crystallinity and improved mechanical properties.

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

100 parts by weight of polylactic acid-polyolefin alloy resin composition As a basis, the polyolefin resin may be 10 to 70% by weight, preferably 30 to 60% by weight. When the amount of polyolefin resin is within 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 can be selected from an olefin-based impact modifier, an acrylic-based impact modifier, and a methacrylate/butadiene/styrene (MBS)-based impact modifier Impact modifier, one is styrene/ethylene/butadiene/styrene (SEBS)-based impact modifier, one is silicon-based impact modifier, and one is polyester-based elastomer At least one of the impact modifiers. Preferably, the impact modifier can be an olefin-based impact modifier, and more preferably an ethylene-α-olefin-based copolymer.

The olefin-based impact modifier is economical, and exhibits excellent impact resistance and good compatibility with polypropylene. In particular, copolymers based on ethylene-α-olefin exhibit excellent elasticity, flexibility, and impact resistance. The copolymer based on ethylene-α-olefin is preferably prepared by a metallocene catalyst.

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

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

When the impact modifier is in this range, polylactic acid resin and polyolefin The main resin has good compatibility, and the polylactic acid-polyolefin alloy resin composition prepared therefrom shows significantly improved impact resistance, plasticity, and heat resistance. Because the impact modifier deteriorates 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 and poor appearance of molded parts can cause impact Occurs when the content of the modifier exceeds 20 parts by weight.

At the same time, the polylactic acid-polyolefin alloy resin composition may include a Antioxidants. The antioxidant can inhibit the yellowing of the polylactic acid resin, and therefore, improve the appearance of the polylactic acid-polyolefin alloy resin composition and the film prepared therefrom. Furthermore, antioxidants can inhibit the oxidation or thermal degradation of the soft segment.

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

When the antioxidant content is about 100ppmw or greater, by Yellowing of the polylactic acid resin caused by oxidation of the flexible component such as the soft segment can be avoided, and the appearance of the polylactic acid-polyolefin alloy resin composition and the film prepared therefrom can be good. Furthermore, when the content of the antioxidant is about 3,000 ppmw or less, the polymerization reaction rate of lactide remains appropriate, and the antioxidant helps the production of hard segments containing polylactic acid repeating units. Therefore, the mechanical properties of polylactic acid resin can be improved.

In situations where antioxidants are used in an optimal amount (for example, in poly In the case of polylactic acid resin and polylactic acid-polyolefin alloy resin composition obtained by adding a specific amount of antioxidant during the polymerization of lactic acid resin), the polymerization conversion and degree of polymerization reaction of polylactic acid resin can be increased, and productivity can be increased . Furthermore, since the film forming method of the polylactic acid-polyolefin alloy resin composition at over 180°C exhibits better thermal stability, it can suppress monomers such as lactide or lactic acid or low molecular weights such as cyclic oligomer chains Material formation.

Therefore, it is possible to provide a packaging film that not only has a better appearance due to the suppression of molecular weight reduction and film color change (yellowing), but also improved flexibility and general properties such as mechanical properties, heat resistance, and blocking resistance. nature.

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

However, because the polylactic acid-polyolefin alloy resin composition can have With an ester repeating unit, the resin composition is easily oxidized or thermally degraded during high-temperature polymerization or high-temperature extrusion or shaping methods. Therefore, it is preferable to use the aforementioned heat stabilizer, polymerization stabilizer, or antioxidant as the antioxidant. Specific examples of antioxidants include heat stabilizers based on phosphoric acid, such as phosphoric acid, trimethyl phosphate, or triethyl phosphate; primary antioxidants based on hindered phenol, such as 2,6-di-tert-butyl Base-p-cresol, octadecyl-3-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, tetrakis[methylene-3-(3,5-di 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] glycol ester; amine-based secondary antioxidants, such as phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylene diamine Amine, or N,N'-bis-β-naphthyl-p-phenylenediamine; secondary antioxidants 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, tris(nonylphenyl) phosphite, triisodecyl phosphite, bis(2,4-tertiary butylphenyl) pentaerythritol Phosphate, or (1,1'-diphenyl)-4,4'-diylbisphosphate tetrakis[2,4-bis(1,1-dimethylethyl)phenyl] ester. its Among them, it is best to use phosphite-based antioxidants combined with other antioxidants.

In addition to the above impact modifiers and antioxidants, polylactic acid-poly The olefin alloy resin composition may additionally contain various known additives, such as anti-hydrolysis agents, nucleating agents, organic or inorganic fillers, plasticizers, chain extenders, UV stabilizers, color stoppers, anti-glare agents, deodorants Agents, flame retardants, weathering agents, antistatic agents, mold release agents, oxidation inhibitors, ion exchangers, coloring materials, and inorganic or organic particles, as long as they have general properties for polylactic acid-polyolefin alloy resin compositions There is no negative effect.

The anti-hydrolysis agent is a reactive compound that can interact with the terminal of polylactic acid The hydroxyl or hydroxyl group reacts. 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 at the end of the polymer chain. The end caps at the place react and hydrolyze. The anti-hydrolysis agent can be a carbodiimide, for example, modified phenylcarbodiimide, poly(tolyl carbodiimide), poly(4,4'-diphenylmethane carbodiimide) Carbodiimide), poly(3,3'-dimethyl-4,4'-diphenylene carbodiimide), poly(p-lane phenylene carbodiimide), poly(in- -Phenylene carbodiimide), or poly(3,3'-dimethyl-4,4'-diphenylmethane carbodiimide). 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.

100 parts by weight of 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 includes a nucleating agent in this range, Its heat resistance and injection moldability can be improved. The nucleating agent can be a sorbitol metal salt, a phosphate metal salt, a quinacridone, a calcium carboxylate, and an organic compound based on amide, preferably a metal salt based on a phosphate.

Examples of plasticizers include phthalate plasticizers, such as phthalic acid two Ethyl, dioctyl phthalate, and dicyclohexyl phthalate; aliphatic dibasic acid ester plasticizers, such as di-1-butyl adipate, di-n-octyl adipate, and di-sebacate N-butyl, and di-2-ethylhexyl azelate; phosphate plasticizers, such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate; polyhydroxycarboxylate plasticizer , Such as tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and tributyl citrate; aliphatic ester plasticizers, such as acetyl ricinoleic acid methyl, And pentyl stearate; polyhydric alcohol ester plasticizers, such as glycerol triacetate; and epoxy plasticizers, such as epoxidized soybean oil, epoxidized linseed oil fatty acid butyl ester, and Epoxidized octyl stearate.

Furthermore, examples of colored pigments include inorganic pigments such as carbon Black, titanium oxide, zinc oxide, and iron oxide; and organic colorants, such as cyanines, phosphoquinones, perurones, isoindolinones, and thioindigo.

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, polymethylmethacrylate, silicon, and the like. There are no special restrictions on the surface treatment of the silica, titanium dioxide or talc. Titanium dioxide with surface treatment in it Or when talc is used, it gives the film a good overall balance of 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 done by a chemical or physical method, using a treatment agent 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. Implement. The average particle size of the inorganic particles may be 1 to 30 μm, preferably 1 to 15 μm. When the average particle size is in this range, a film containing these particles exhibits improved heat resistance and stiffness.

Furthermore, it can be applied to polylactic acid-polyolefin alloy resin composition The various additives of its film can be used, and the types and purchase paths of such films are known to those who are familiar with the art.

At the same time, the polylactic acid-polyolefin alloy resin composition is used in pellet production It may have a color-b value of less than 10, preferably 5 or less. Because the yellowing of 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 film appearance 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 unit based on polyolefin>

First, a hydroxyl group is introduced to the end of a polymer (poly1,2-butadiene or poly1,3-butadiene) prepared by copolymerization of butadiene monomer, and then A hydrogenation reaction is performed to form a hydroxyl-terminated polybutadiene (HTPB) with a number average molecular weight of 1,000 to 3,000 to obtain a Polyolefin (co)polymer based on polyol structural unit. This method can be carried out by a traditional method for preparing polyolefin-based polyol (co)polymers.

<Preparation of polyol repeating unit A based on polyolefin>

Then, a (co)polymer containing polyolefin-based polyol structural units, a monofunctional isocyanate compound, and a urethane reaction catalyst are filled in a reactor and received during heating and stirring A urethane reaction. Due to this reaction, the two isocyanate groups of the diisocyanate compound and the terminal hydroxyl group of the (co)polymer combine to form a urethane bond. Therefore, a (co)polymer containing a polyurethane polyol repeating unit is formed, wherein the polyolefin-based polyol structural unit is in a linear or branched manner via a urethane bond Connected, these units serve as one of the soft segments in the polylactic acid resin. Polyurethane polyol (co)polymers can be in the form of EUEUE or EU(-E)-EUE. Among them, the polyolefin-based polyol repeating unit (O) is through a urethane The bond (U) is connected in a linear or branched manner, and the polyolefin-based polyol repeating unit is connected to the two terminals.

<Preparation of polyol repeating unit B based on polyolefin>

Furthermore, a (co)polymer containing polyolefin-based polyol structural units, 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 with the hydroxyl group of the (co)polymer to form an ester bond. Therefore, a A (co)polymer containing a polylactic acid resin repeating unit (L) and a polyolefin-based polyol repeating unit, wherein the polyolefin-based polyol structural unit is connected to a linear or via an ester bond Branch connection. Polyolefin-based polyols and polylactic acid resin (co)polymers can be in the form of LEOEL, in which the polyolefin-based polyol repeating unit (O) repeats with the polylactic acid resin via the ester bond (E) The unit is connected at two terminals.

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

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

The urethane reaction can be carried out in the presence of a tin catalyst, for example, tin octoate, dibutyl tin dilaurate, dioctyl tin 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 polyolefin-based polyol (co)polymers are reacted in the presence of a urethane reaction catalyst under a nitrogen atmosphere at 70 to 80°C for 1 to 5 hours to produce One of the repeating units of polyolefin polyol (co)polymer.

Thereafter, the polylactic acid-polyolefin alloy resin composition containing block copolymers (or polylactic acid resins containing this copolymer) and antioxidants can be modified by antioxidants and polyolefin-based polyol repeating units. The (co)polymer is prepared by polycondensation reaction of lactic acid (D- or L-lactic acid) or ring-opening polymerization reaction 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, and resin yellowing due to oxidation of the soft segment can be suppressed by an antioxidant. During this process, the polyurethane polyol repeating unit system is bonded with at least some of the terminal groups of the polylactic acid repeating unit to produce a block copolymer.

Furthermore, a prepolymer can be made by making polyolefin-based polyols Prepared in combination with lactide. Then, the prepolymer can undergo a chain extension reaction with a diisocyanate compound to obtain a known polylactic acid-based copolymer, and react with an isocyanate compound having at least two functional groups to obtain a known branched copolymer The polylactic acid-polyolefin alloy resin composition containing the copolymer can be prepared.

At the same time, the ring-opening polymerization reaction of lactide can be catalyzed by a metal It is implemented in the presence of agents, such as alkaline earth metals, rare earth metals, transition metals, aluminum, germanium, tin, and antimony. More particularly, 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 lactide The ring-opening polymerization reaction can be carried out continuously in the same reactor where the urethane reaction has occurred. In other words, a polyolefin-based polyol polymer and an isocyanate compound undergo a urethane reaction to produce a polymer containing polyolefin-based polyol repeating units, and then, such as Monomers and catalysts such as lactide are continuously added to the same reactor to obtain a repeating unit of polylactic acid. Therefore, a polymer containing a polyolefin-based polyol repeating unit is used as a starting agent, and a polylactic acid repeating unit and a polylactic acid resin containing the repeating unit can be continuously produced with high yield and productivity. In a similar manner, a polyolefin-based polyol undergoes a ring-opening polymerization reaction with a lactide initiator, and then an isocyanate compound is continuously added to the same reactor to perform a chain extension reaction in order to achieve high yield Rate and productivity to obtain polylactic acid repeating unit and polylactic acid resin containing this repeating unit.

Because the polylactic acid-polyolefin alloy resin composition contains a block Copolymer (polylactic acid resin), in which specific hard and soft segments are combined, can exhibit more improved flexibility, and at the same time show the biodegradability of polylactic acid resin. Furthermore, this resin composition can minimize the outflow of the soft segment that causes flexibility, and can largely avoid the moisture resistance, mechanical properties, heat resistance, transparency, or turbidity of the film due to the soft segment induced The reduction.

In addition, polylactic acid-polyolefin alloy resin is prepared to have a characteristic The glass transition temperature is different, and one of the selectivity is the melting temperature (Tm). Therefore, a film prepared therefrom exhibits optimized flexibility and stiffness as a packaging material, and also has good melt processability, blocking resistance 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, due to the antioxidant Existing, polylactic acid resin can be suppressed, and polylactic acid-polyolefin alloy resin composition containing these components can be manufactured with significantly improved flexibility and A packaging film with excellent mechanical properties, better general properties, and better appearance and product quality.

In other words, the composition of the polylactic acid-polyolefin alloy resin of the present invention The compound contains a polyolefin-based polyol repeating unit as a soft segment. Therefore, the film prepared from the polylactic acid-polyolefin alloy resin composition exhibits significantly improved flexibility.

Furthermore, compared with polylactic acid resin (ie, hard segment), it is non-polar The soft segment polyolefin-based polyol 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 are modified by the following examples Explain clearly. However, these examples are only provided for illustrative purposes, and the present invention is not limited thereto.

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

1. Polyol repeating units based on polyolefins and their counterparts

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

-HTPB 2.0: a 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 a butadiene monomer The terminal group of olefin or poly 1,3-butadiene) is then prepared by hydrogenation reaction.

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

-PEG 8.0: polyethylene glycol with a number average molecular weight of 8,000.

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

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

-HDI: Hexamethylene diisocyanate

-TDI: 2,4- or 2,6-tolylylene 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-based organic carbon with an optical purity of 99.5% or higher

4. Antioxidant 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'-diylbisphosphate tetrakis[2,4-bis(1,1-dimethylethyl)phenyl] ester

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

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

5. Polyolefin resin, etc.

-JSS-370N: polyethylene-propylene block copolymer, which is manufactured by Honam Petrochemical Corp., has a melt index of 35 g/10 minutes (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 minutes (230°C, 2.16 kg), a heat distortion temperature of 105°C, and 95 to 96% Of II

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

6. Impact modifier, etc.

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

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

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

-Biostrength 150: A core/shell impact modifier based on acrylic, manufactured by ARKEMA

7. Inorganic fillers and nucleating agents, etc.

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

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

-TF-1: N,N',N"-tricyclohexyl-1,3,5-benzenetrimethamide, 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., has a graft ratio of 3.9%

Preparation examples 1 to 6: Preparation of polylactic acid resin A to F

According to the components and amounts shown in Table 1 below, the reactants and a catalyst are filled in an 8 liter reactor, which is equipped with a nitrogen tube, a Stirrer, a catalyst inlet, a stream condenser, and a vacuum system. Based on the total weight of the reactants, the amount of dibutyltin dilaurate is 130 ppmw as a catalyst. Under a nitrogen atmosphere, the monourethane reaction was carried out at 70°C for 2 hours, and then 4 kg of L-(or D-) lactide was supplied into the reactor, after which it was flushed with nitrogen five times.

After that, the reaction mixture was heated to 150°C to completely dissolve L-(or D-) lactide. Based on the total weight of the reactants, the 120 ppmw 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 1 kg of nitrogen pressure, the reaction was carried out at 185°C for 2 hours. 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 deactivate the catalyst. After the catalyst is inactivated, vacuum conditions are applied until the pressure reaches 0.5 Torr to remove unreacted L-(or D-) lactide (about 5% by weight 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 grams of HTPB 2.0, 3.9 grams of L-lactide and 0.1 kilograms of D-lactide are filled in an 8 liter reactor, which is equipped with a nitrogen pipe, a stirrer, and a The catalyst inlet, the first discharge 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 tin 2-ethylhexanoate was diluted with 500 ml of toluene, and the diluted solution was supplied to the reactor through the catalyst inlet. Under 1 kg of nitrogen pressure, the reaction was carried out at 185°C for 2 hours. 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 deactivate the catalyst. After the catalyst is inactivated, apply a vacuum condition until the pressure reaches 0.5 Torr to remove unreacted L-lactide (about 5 wt% of the initial supply weight). Then, the HDI as shown in Table 1 and the dilution of the 120 ppmw dibutyltin dilaurate catalyst in 500 ml of toluene were 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 later introduced, a polylactic acid resin series Prepared according to the same procedure as in 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, polyols and 4 kg of L-lactide are packed in an 8 liter reactor, which is equipped with a nitrogen pipe, a stirrer, a catalyst inlet, a first-pass condenser, and A vacuum system, followed by nitrogen flushing five times. Thereafter, the reaction mixture was heated to 150°C to completely dissolve lactide. Based on the total weight of the reactants, the 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 1 kg of nitrogen pressure, the reaction was carried out at 185°C for 2 hours. 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 deactivate the catalyst. After the catalyst is inactivated, apply a vacuum condition 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

Except for using 6 grams of 1-dodecanol instead of polyol as shown in Table 1, a polylactic acid resin was prepared according to the same procedure as in Preparation Example 9. 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 filled into an 8 liter reactor, which is equipped with a nitrogen tube, a stirrer, a catalyst inlet, and the first effluent condensation And a vacuum system, followed by flushing with nitrogen five times. Based on the total weight of the reactants, the amount of dibutyltin dilaurate is 130 ppmw as a catalyst. Under a nitrogen atmosphere, the monourethane 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. The amount of 120ppmw was used as an addition polymerization catalyst, and the amount of 1,000 as the monoester and/or ester amide exchange catalyst was dibutyltin dilaurate through the catalyst inlet, and 500 Dilute with 1 ml of toluene Under 1 kg of nitrogen pressure, the reaction was carried out at 190°C for 2 hours. 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 deactivate the catalyst. After the catalyst is inactivated, apply a vacuum condition 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 resin prepared in Preparation Examples 1 to 11 was reduced under a low vacuum of 1 Torr, dried at 80°C for 6 hours, and mixed with the polypropylene and the polypropylene shown in Tables 2 and 3 below in a super mixer. Mix other materials. The mixture thus obtained is subjected to a 19-mm twin screw extruder (in addition, such as a single screw extruder, a roll mill, a kneader, or a Banbury mixer at an extrusion temperature of 200 to 230°C). Various known equipment can be used) kneading and extruding into a strand shape. The strands thus formed are cooled in a water bath and cut into pellets with a pelletizer. Therefore, the prepared pellets were dried in a hot air dryer at 80°C for 4 hours, and then subjected to injection molding to obtain film samples. Film samples were evaluated, and the results are shown in Tables 2 and 3.

Experimental example

The molecular weight distribution, Tg, Tm and %C _bio 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: The isocyanate group of a diisocyanate compound (for example, hexamethylene diisocyanate) used in a reaction to form a polyolefin-based polyol repeating unit/polyether-based polyvalent The molar ratio of the terminal hydroxyl group of the alcohol repeating unit (or (co)polymer).

(2) OHV (KOH mg/g): by dissolving polyolefin-based polyol repeating units (or (co)polymers) in dichloromethane, the repeating units are acetylated, and the The glycated repeating unit is hydrolyzed to produce acetic acid, which is measured by titrating the acetic acid with 0.1N KOH in methanol. It corresponds to the terminal hydroxyl group of polyol repeating unit (or (co)polymer) based on polyolefin The number of regiments.

(3) Mw and Mn (grams/mole) and molecular weight distribution (Mw/Mn, MWD): Measured by subjecting a 0.25% by weight polylactic acid resin solution in chloroform to gel permeation chromatography (manufactured by Viscotek TDA 305, 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): to quench a molten sample, Then, while 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 judged by the middle value of an endothermic curve and the tangent of a baseline.

(5) Tm (melting temperature, °C): to quench a molten sample, Then, while increasing the temperature of the sample at a rate of 10°C/min, measure it with a differential scanning calorimeter (manufactured by TA Instruments). Tm is determined from the maximum value of the melting endothermic peak of crystallization.

(6) Residual monomer (lactide) content (wt%): by making 0.1 g The resin was dissolved in 4 ml of chloroform, 10 ml of hexane was added, and the resulting mixture was filtered, and then subjected to GC analysis for measurement.

(7) The content of polyol repeating units based on polyolefins (weight %): The content of the polyolefin-based polyol repeating unit in the prepared polylactic acid resin is measured using a 600MHz nuclear magnetic resonance (NMR) spectrometer.

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

(9) The organic carbon content of biomass-based carbon (%C _bio ): According to ASTM D6866, a test measurement used to measure the content of biomass-based materials based on organic radiocarbon (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) Extrusion: The polylactic acid-polyolefin alloy resin is extruded into a strand type by a 30-mm twin-screw extruder equipped with a die at 200 to 250°C, and the extruded strand Cured in a water bath at 20°C. At this time, the melt viscosity and uniformity of the extrudate were observed with naked eyes. The melt viscosity uniformity conditions (extrudability) are evaluated based on the following standards: ◎: 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, the strand is prepared with some cracks; and ×: Due to the extremely low compatibility between the two resins and the poor melt viscosity uniformity, the strand is prepared with cracks and mold expansion.

(2) Melt Index (MI): Measured at 210°C, 2.16kgf in accordance with ASTM D1238, and indicated by the average of three measurements.

(3) Compatibility: Polylactic acid resin and polylactic acid-polyolefin alloy resin are extruded at 200 to 250°C using a 30-mm twin-screw extruder equipped with a hole die, and the extrudate is at 20°C. Cured in a water bath to obtain a strand sample. The strand sample is immersed in liquid nitrogen and cut. The cutting surface uses a scanning electric Observed by a sub-microscope (SEM) and evaluated according to the following criteria: ◎: The two resins are well dispersed, and the particle size of the undispersed resin is 0.2μm or less; ○: The two resins are still dispersible and the undispersed resin The particle size is 1.0 μm or less; and ×: 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: The appearance of the sample is as follows. The appearance of the sample is checked by naked eyes for flow marks, weld lines and reduced gloss caused by reduced fluidity: ◎: No flow marks and weld lines due to good melt viscosity, and good surface gloss; ○: There are no flow marks and weld lines due to slightly high melt viscosity, but the gloss is reduced; and ×: Flow marks, weld lines, and gloss are reduced due to extremely high melt viscosity.

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

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

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

(8) Flexural strength (kgf/cm ² ) and flexural modulus (kgf/cm ² ): A test sample is prepared according to ASTM D790, and the flexural strength and flexural modulus are 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 film surface is evaluated on an A4 size film sample by tactile sensation according to the following standards: ◎: no outflow; ○: outflow, But not serious; and ×: serious 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 for 30 days at a temperature of 40°C and a humidity of 90% RH. The tensile strength is measured and compared with the initial tensile strength value.

(12) Odor: The high volatile odor from the discharged extruded mixture after the mixing method is checked:

◎: Bad smell detected

×: No bad smell detected

(13) Total Volatile Organic Compounds (TVOC): Headspace

-GC/MS analysis

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

2) STD: Toluene standard solution (50μL) of one series of 250, 500 and 1000ppm is prepared and sealed in a bottle, and analyzed by HS-GC/MS

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°C (5 minutes) -10°C/min -320°C (16 minutes), inject at 280°C, split 1:30

With reference to Table 2, Examples 1 to 5 and 7 to 8 represent molded products prepared from polylactic acid-polyol ether alloy resin compositions. These resin compositions are Lactic acid resin contains 5 to 35% by weight of soft segment (polyolefin-based polyol repeating unit), has a low color-b value, contains an appropriate amount of antioxidant, and has a weight of 100,000 to 400,000 Average molecular weight and molecular weight distribution from 1.60 to 3.0, Tg from 20 to 60°C, and Tm from 145 to 178°C. Furthermore, Example 6 shows a molded product prepared from a polylactic acid-polyether alloy resin composition containing a conventional polylactic acid resin (resin J) and a polylactic acid resin (resin F) of the present invention.

These molded products of Examples 1 to 8 exhibit excellent mechanical properties, such as an initial tensile strength of 200kgf/cm ² or more, and an impact strength of 5kgf-cm/cm or more, and show 100°C or more It has good heat resistance expressed by high temperature mold HDT. Furthermore, when the sample is adjusted for 30 days at a temperature of 40°C and a humidity of 90% RH, the molded product has a tensile strength retention rate 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 has no outflow, so it effectively reduces the total volatile organic compounds harmful to the human body. In addition, these molded products are considered to be environmentally friendly materials due to their total biomass content of 25% or more.

In contrast, the molded product of Comparative Example 1 prepared from the polylactic acid-polyolefin alloy resin containing a traditional polylactic acid resin A shows good general properties, but the sample has a total biomass content of less than 25%. Therefore, It cannot comply with 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 a traditional polylactic acid resin J lacks compatibility between the polylactic acid resin and the polypropylene resin, and this resin There is a big difference in melt viscosity between them; therefore, the final product is not suitable as a molded product because it has poor extrudability, which is included in the mold expansion 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 a polylactic acid resin J in combination with a compatibilizer, the extrusion The performance is good, but the compatibility between the two resins is not sufficient to impart satisfactory general mechanical properties, moisture resistance, or heat resistance to the final molded product. Furthermore, the use of compatibilizers causes serious odor and flow problems.

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

Furthermore, Comparative Examples 6 and 7 show that by making a polylactic acid resin J and An aliphatic polyester polyol is simply mixed and kneaded, and then the resulting mixture is subjected to injection molding to prepare. This aliphatic polyester polyol is prepared by making a plasticizer with a number average molecular weight of 2,400 ( 1,3-propanediol), 1,4-butanediol with a number average molecular weight of 11,000, succinic acid, and adipic acid are prepared by the polycondensation reaction. The polylactic acid resin does not contain polyolefin-based multi-component Alcohol repeating unit (soft segment). Due to the unsatisfactory dispersibility of the plasticizer among 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 nature.

Furthermore, the molded product of Comparative Example 8 is self-contained with broad molecular A polylactic acid resin and a polyester polyol repeating unit are prepared by a polylactic acid-polyolefin alloy resin. Because the molded product of Comparative Example 8 has a polyurethane that is randomly introduced as a softening component in the form of small segments, it exhibits relatively better flow resistance and TVOC properties. However, due to the relatively small size of the polylactic acid repeating unit, the molded product exhibits poor heat resistance (such as low Tm), and because of compatibility issues, the mechanical properties are also poor. Furthermore, due to the poor compatibility between the polypolyol 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 amine exchange reaction during resin preparation, a broad molecular weight distribution is observed, resulting in uneven melting properties, poor film extrusion properties, mechanical properties, and moisture resistance.

At the same time, the pellets prepared in Examples 1 to 3 and Comparative Examples 2 and 4 were observed by scanning electron microscopy, and the results are individually illustrated in Figures 1 to 5. 1 to 5, the white part represents a polylactic acid resin, and the black part represents a polypropylene resin.

Compared with Figures 4 and 5, in Figures 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, and it also indicates improved flexural modulus and impact strength. In particular, it can be concluded that these pellets have improved compatibility compared to Figure 5 where a compatibilizer is used.

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

Claims (15)

A polylactic acid-polyolefin alloy resin composition comprising: (1) 30 to 90 parts by weight of polylactic acid resin, (2) 70 to 10 parts by weight of polyolefin-based resin, and (3) 100 parts by weight Parts by weight of the polylactic acid resin (1) and the sum of the polyolefin-based resin (2), 0.1 to 20 parts by weight of an impact modifier, wherein the polylactic acid resin (1) contains a A hard segment, which includes a polylactic acid repeating unit of formula 1; and a soft segment, which includes a polyolefin-based repeating unit of polyol, wherein the polyolefin-based repeating unit of formula 2 is Alcohol structural units are connected in a linear or branched manner via a urethane bond or an ester bond; wherein the organic carbon content (%C _bio ) of the biomass-based carbon as defined in Equation 1 is at least 60 % By weight, where n is an integer from 700 to 5,000 in chemical formulas 1 and 2, m+1 is an integer from 5 to 200, and 1 is an integer from 1 to 200:

[Chemical formula 2]

[Equation 1] %C _bio = (weight ratio of ¹⁴ C isotope to ¹² C of total carbon content in the polylactic acid resin)/( ¹⁴ C isotope pair of total carbon content in biomass-based carbon standard materials ¹² C weight ratio). The polylactic acid-polyolefin alloy resin composition of claim 1, wherein, based on the total weight of carbon in the polylactic acid resin, the content of the ¹⁴ C isotope is 7.2 x 10 ^-11 to 1.2 x 10 ^{-10 by} weight %. 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 of claim 1, wherein the polylactic acid resin has a number average molecular weight of 50,000 to 200,000, and a weight average molecular weight of 100,000 to 400,000. The polylactic acid-polyolefin alloy resin composition of 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 of claim 1, wherein the urethane bond is through the polyolefin-based polyol structural unit or through the polyolefin-based polyol One of the prepolymer prepared by the addition polymerization between the terminal hydroxyl group of the structural unit and lactide The terminal hydroxyl group is formed by reacting with a diisocyanate or a di- or higher-functional isocyanate compound. The polylactic acid-polyolefin alloy resin composition of claim 1, wherein the polylactic acid resin comprises a polylactic acid repeating unit contained in the hard segment in which the terminal carboxyl group is connected to each other via an ester bond A block copolymer in which the terminal hydroxyl groups of the polyolefin-based polyol structural units contained in the soft segment are connected, or a block copolymer in which the block copolymer is connected via a urethane bond A linear or branched block copolymer. The polylactic acid-polyolefin alloy resin composition of claim 7, wherein the polylactic acid resin further comprises a polylactic acid homopolymer, which is kept uncoupled with the polyolefin-based polyol repeating unit. The polylactic acid-polyolefin alloy resin composition of claim 1, wherein the polymer of the polyolefin-based polyol repeating unit has a number average molecular weight of 1,000 to 100,000. The polylactic acid-polyolefin alloy resin composition of claim 6, wherein the terminal hydroxyl group of the polyolefin-based polyol structural unit is the diisocyanate or the diisocyanate compound of higher functionality The molar ratio of isocyanate groups ranges from 1:0.50 to 1:0.99. The polylactic acid-polyolefin alloy resin composition of claim 1, wherein, per 100 parts by weight of the polylactic acid resin, the polylactic acid resin contains the hard segment in an amount of 65 to 95 parts by weight, and 5 to 35 parts by weight Parts by weight of the soft segment. The polylactic acid-polyolefin alloy resin composition of claim 1, wherein the Polyolefin-based resin is a propylene homopolymer, or a propylene and at least one selected from ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene Copolymers made from olefins of the group. Such as the polylactic acid-polyolefin alloy resin composition of claim 1, wherein the polyolefin-based resin is a highly crystalline polyolefin resin. When determined by the xylene soluble (Xs) test, the polyolefin resin The olefin resin has a random part of polypropylene of 12% or less. Such as the polylactic acid-polyolefin alloy resin composition of claim 1, which has a color-b value of less than 10. The polylactic acid-polyolefin alloy resin composition of claim 1, based on the total weight of the polylactic acid resin, contains residual monomers in an amount of less than 1% by weight.

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