JP2015155491A - Polylactic acid-based resin composition and sheet-like molding comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition which is excellent in transparency and impact resistance and can be used for a food film and the like requiring transparency, and to provide a sheet-like molding.

SOLUTION: The polylactic acid-based resin composition contains a polylactic acid resin (A), a polyalkylene ether (B), and an acrylic resin (C) having a weight-average molecular weight of 500,000 or more. The polylactic acid-based resin composition contains, based on 100 pts.mass of the polylactic acid resin (A), 1-10 pts.mass of the polyalkylene ether (B) and 0.3-10 pts.mass of the acrylic resin (C).

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a polylactic acid-based resin composition excellent in transparency and impact resistance, and a sheet-like molded body comprising the resin composition.

  Films used as packaging materials for newspapers, magazines, foods, etc. are desired to be formed of biodegradable resins in accordance with the recent increase in social demand for environmental protection. Among the biodegradable resins, polylactic acid resin is widely present in nature, has almost no harm to animals, plants and animals, has a melting point of 140 to 175 ° C., has sufficient heat resistance, and has very high transparency. At the same time, it is a relatively inexpensive thermoplastic resin, and can be produced from plant-derived raw materials.

  However, since sheets and films made of polylactic acid resin are very hard and brittle as they are, it has been difficult to use them in fields where impact resistance is required.

Various studies have been conducted to improve the impact resistance and flex resistance of polylactic acid resin. For example, Patent Document 1 discloses a heat shrink film made of a mixed resin containing a polylactic acid resin and a silicone-acrylic composite rubber. Further, Patent Document 2 discloses that impact resistance at low temperature is improved by adding epoxidized natural rubber to polylactic acid resin.
However, although the resin compositions described in Patent Documents 1 and 2 have improved impact resistance, the transparency, which is an advantage of polylactic acid, is impaired, and therefore, for applications such as food films and industrial films that require transparency. It was difficult to use.

  Furthermore, Patent Document 3 discloses a resin composition containing a polylactic acid resin and a multilayer structure polymer. In order to improve impact resistance, flexibility, and flex resistance, the resin composition is substantially added with at least about 10% by mass of one kind of multilayer structure polymer. However, this resin composition has a problem that when one kind of multilayer structure polymer is added in an amount of about 10% by mass and the addition amount of the multilayer structure polymer is increased, the transparency is lowered.

JP 2007-177140 A US Pat. No. 6,456,631 JP 2003-286396 A

  The present invention solves the above-mentioned problems, and is excellent in transparency and impact resistance, and can be used for food films and the like that require transparency, and a polylactic acid resin composition and sheet form Providing a molded body is a technical problem.

  As a result of repeated studies to solve the above problems, the present inventors have added a specific amount of polyalkylene ether (B) and a specific molecular weight acrylic resin (C) to the polylactic acid resin (A). Thus, the present inventors have found that a polylactic acid-based resin composition having excellent impact resistance can be obtained without impairing transparency, and the present invention has been achieved.

That is, the gist of the present invention is as follows.
(1) A resin composition containing a polylactic acid resin (A), a polyalkylene ether (B) and an acrylic resin (C) having a weight average molecular weight of 500,000 or more, wherein the polylactic acid resin (A) is 100 masses 1 to 10 parts by mass of the polyalkylene ether (B) and 0.3 to 10 parts by mass of the acrylic resin (C) with respect to parts, a polylactic acid-based resin composition.
(2) A sheet-like molded article obtained by molding the polylactic acid-based resin composition described in (1) above.

  The polylactic acid resin composition of the present invention is obtained by adding a specific amount of polyalkylene ether (B) and an acrylic resin (C) having a specific molecular weight to the polylactic acid resin (A). Impact resistance is improved while maintaining the high transparency inherent in the resin. Therefore, the polylactic acid resin composition of the present invention is particularly suitable for use in applications such as films and sheets. And since the sheet-like molded object of this invention is shape | molded from the polylactic acid-type resin composition of this invention, it is excellent in transparency and impact resistance, and is used for foodstuffs and industrial use in which transparency is calculated | required. It can also be used for film applications.

Hereinafter, the present invention will be described in detail.
The resin composition of the present invention contains a polylactic acid resin (A), a polyalkylene ether (B) and an acrylic resin (C) having a specific molecular weight.
First, the polylactic acid resin (A) will be described.
Examples of the polylactic acid resin (A) in the present invention include poly-L-lactic acid in which the structural unit of lactic acid is L-lactic acid, poly-D-lactic acid in which the structural unit is D-lactic acid, and a combination of L-lactic acid and D-lactic acid. Examples thereof include poly DL-lactic acid which is a polymer, or a mixture thereof.

In the present invention, as the polylactic acid resin (A), either a crystalline polylactic acid resin or an amorphous polylactic acid resin may be used, but the operability when obtaining a molded body, and further imparting heat resistance to the molded body. In view of this, it is preferable to use a crystalline polylactic acid resin.
The crystalline polylactic acid resin here refers to a polylactic acid resin having a melting point in the range of 140 to 175 ° C., and the amorphous polylactic acid resin refers to a polylactic acid resin having substantially no melting point. .

  In order to make the polylactic acid resin (A) a crystalline polylactic acid resin, the D-form content in the polylactic acid resin (A) is preferably 5 mol% or less, more preferably 2 mol% or less. preferable. When the D-form content exceeds 5 mol%, the crystallinity of the polylactic acid resin is lowered, and it is necessary to add a crystal nucleating agent. It does not crystallize, the operability in obtaining a molded product is lowered, and the obtained molded product tends to be inferior in heat resistance.

  When polyalkylene ether (B) and acrylic resin (C) having a specific molecular weight are added to polylactic acid resin (A), crystallization of polylactic acid resin (A) may be inhibited. However, when the polylactic acid resin (A) is a crystalline polylactic acid resin, the inhibitory action is reduced, and furthermore, the resistance by adding a polyalkylene ether (B) and an acrylic resin (C) having a specific molecular weight is reduced. The impact imparting effect is further improved.

  The weight average molecular weight of the polylactic acid resin (A) is preferably 100,000 to 300,000, and more preferably 120,000 to 200,000. When the weight average molecular weight of the polylactic acid resin (A), which is the main component of the resin composition, is less than 100,000, the resulting molded product tends to be inferior in mechanical properties. On the other hand, if the weight average molecular weight exceeds 300,000, the melt viscosity becomes too high, and melt extrusion tends to be difficult when obtaining a molded product.

  The amount of residual lactide in the polylactic acid resin (A) is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and preferably 0.1% by mass or less. Most preferred. When the amount of residual lactide exceeds 0.5% by mass, when obtaining a molded product, for example, when forming a sheet or film, smoke is significantly generated, equipment near the die is contaminated, the product quality is lowered, and the operability is reduced. It is easy to fall. Furthermore, the obtained molded product may be inferior in durability.

  The polylactic acid resin composition of the present invention is mainly composed of the polylactic acid resin (A), and the content of the polylactic acid resin (A) is 80 to 99% by mass of the entire resin composition. Is more preferable, 85 to 98% by mass is more preferable, and 90 to 96% by mass is most preferable. If the content of the polyresin resin (A) is too large, the contents of the polyalkylene ether (B) and the acrylic resin (C) will be too small, and the effect of improving impact resistance will be poor. On the other hand, when the content of the polylactic acid resin (A) is small, the transparency of the resin composition is lowered and the amount of the biodegradable resin used is small, so that it cannot be said to be an environmentally friendly resin composition. .

  In the present invention, various commercially available polylactic acid resins can be used as the polylactic acid resin (A), and different types can be used in combination. Also, lactide, which is a cyclic dimer of lactic acid, is used as a raw material, and a product produced by a known melt polymerization method or further using a solid phase polymerization method can be used.

Next, the polyalkylene ether (B) will be described.
In the present invention, examples of the polyalkylene ether (B) include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc., which have good compatibility with the polylactic acid resin (A) and have the effect of maintaining transparency. Polyethylene glycol is preferred because it is high.

  In the present invention, it is mainly an acrylic resin (C) having a specific molecular weight that exhibits the impact resistance improving effect of the resin composition. The polyalkylene ether (B) acts as a lubricant or plasticizer, thereby increasing the dispersibility of the acrylic resin (C) and making it easier to express the impact resistance improvement effect. It is done.

  In the present invention, the number average molecular weight of the polyalkylene ether (B) is preferably 5000 or more, more preferably 7000 or more, and further preferably 8000 to 30000. When the number average molecular weight is less than 5,000, the impact resistance improving effect tends to be insufficient, bleeding out and workability may be deteriorated. On the other hand, when the number average molecular weight exceeds 30000, the compatibility with the polylactic acid resin (A) is lowered, and the effect of improving impact resistance may be insufficient.

  The content of the polyalkylene ether (B) needs to be 1 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A), preferably 2 to 8 parts by mass. More preferably, it is -7 mass parts. When the content of the polyalkylene ether (B) is less than 1 part by mass, the effect of improving the impact resistance as described above cannot be easily achieved. On the other hand, when the content of the polyalkylene ether (B) exceeds 10 parts by mass, the transparency of the resulting resin composition is lowered.

Next, the acrylic resin (C) will be described.
The acrylic resin (C) in the present invention is preferably composed of monomers such as acrylic acid and esters thereof, methacrylic acid and esters thereof, or a homopolymer of only one of these monomers, or two of them. Any of the above-mentioned monomer copolymers may be used, and the copolymer may be a block copolymer, a random copolymer, a graft copolymer, or a copolymer thereof. Among them, it is more preferable to use acrylic acid ester or methacrylic acid ester because they have good compatibility with polylactic acid resin and can maintain transparency.
Specific examples of acrylic esters and methacrylic esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, neopentyl (meth) acrylate, ethylhexyl (meth) acrylate, isodecyl acrylate, lauryl (meth) acrylate , Tridecyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth ) Chloroethyl acrylate, (meth) acrylic acid tri Ruoroechiru, (meth) heptadecafluorooctyl acrylate, (meth) acrylic acid isobornyl, and the like (meth) adamantyl acrylate and (meth) tricycloalkyl Desi sulfonyl acrylate.
Moreover, monomers, such as substituted styrenes, such as styrene, (alpha) -methylstyrene, t-butylstyrene, and chlorostyrene, can also be copolymerized.

  There is no restriction | limiting in particular as a polymerization method of acrylic resin (C), Well-known methods, such as solution polymerization, suspension polymerization, block polymerization, are used.

  The acrylic resin (C) needs to have a weight average molecular weight of 500,000 or more, preferably 700,000 or more, more preferably 800,000 to 8 million. If the weight average molecular weight of the acrylic resin (C) is less than 500,000, the effect of improving impact resistance cannot be sufficiently achieved. On the other hand, if the weight average molecular weight exceeds 8 million, the compatibility of the resulting resin composition is impaired, or the melt viscosity becomes too high, and it may be difficult to sufficiently improve the impact resistance. .

  Examples of commercially available acrylic resins (C) include the Metablene P series manufactured by Mitsubishi Rayon Co., Ltd., the PARALOID K series manufactured by Rohm & Haas, and the Kane Ace PA series manufactured by Kaneka.

  The content of the acrylic resin (C) needs to be 0.3 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A), and preferably 1 to 8 parts by mass. It is more preferable that it is 2-6 mass parts. If content of acrylic resin (C) is less than 0.3 mass part, it will become difficult to obtain the resin composition excellent in impact resistance. On the other hand, when the content of the acrylic resin (C) exceeds 10 parts by mass, the obtained resin composition is not only inferior in transparency, but also fluidity is greatly reduced during molding, and the operability is lowered. .

  In the polylactic acid resin composition of the present invention, the mass ratio (B / C) of the polyalkylene ether (B) and the acrylic resin (C) is preferably 80/20 to 50/50. By containing both components in such a ratio, impact resistance is more effectively imparted.

Obtaining a polylactic acid resin composition excellent in both transparency and impact resistance has been difficult with conventional techniques. However, in the study by the present inventors, the polyalkylene ether (B) and the acrylic resin (C) having a specific molecular weight are selected, both are used in combination, and the polylactic acid is contained. It was found that there is an effect of sufficiently improving the impact resistance while maintaining the transparency of the resin (A). Although the mechanism is unknown, it is assumed that the polylactic acid resin (A) and each additive are excellent in compatibility, and these are well dispersible in the resin composition.
Therefore, even if the polyalkylene ether (B) and the acrylic resin (C) are added to the resin composition little by little, the effects exerted by each of them are sufficiently exhibited. As a result, it is possible to obtain a polylactic acid-based resin composition that is remarkably excellent in impact resistance without impairing the transparency of the polylactic acid resin (A).

When the polylactic acid resin composition of the present invention is used, a molded article excellent in transparency and impact resistance can be obtained. Among the molded articles obtained from the resin composition of the present invention, in the case of a sheet having a thickness of 100 to 500 μm, the haze value (indicating the measurement method in Examples described later) as an index indicating transparency is 10% or less. Is possible. Among them, the haze value is preferably 7% or less, and more preferably 6% or less. A sheet having a haze value exceeding 10% is inferior in transparency. For example, when used as a packaging material, it is difficult to confirm the contents.
In the case of a film having a thickness of 10 to 100 μm, the haze value can be 5% or less. Among them, the haze value is preferably 4% or less, and more preferably 3% or less. When the film has a haze value exceeding 4%, the transparency is inferior. For example, when used in a packaging material, it is difficult to confirm the contents.

Among the molded articles obtained from the resin composition of the present invention, in the case of an unstretched sheet having a thickness of 100 to 500 μm, an impact strength that is an index indicating impact resistance (the measurement method is described in Examples described later) is 0.3 J. This can be done. Among them, the impact strength is preferably 0.4 J or more, and more preferably 0.5 J or more.
Further, in the case of a stretched film having a thickness of 10 to 100 μm, the impact strength (the measurement method is described in Examples described later) can be 0.6 J / 100 μm or more. Among them, the impact strength is preferably 0.8 J / 100 μm or more, and more preferably 0.9 J / 100 μm or more. The impact strength is higher than the unstretched sheet due to the stretch orientation.

  In addition, in the polylactic acid-type resin composition of this invention, if it is a range which does not impair an effect, you may contain other resins other than a polylactic acid resin (A).

Examples of such other resins include polyolefin, polyester, polyamide, polycarbonate, polystyrene, polymethyl (meth) acrylate, poly (acrylonitrile-butadiene-styrene) copolymer, liquid crystal polymer, and polyacetal.
Examples of the polyolefin include polyethylene and polypropylene.
Examples of the polyamide include polyamide 6, polyamide 66, polyamide 610, polyamide 11, polyamide 12, polyamide 6T, polyamide 9T, and polyamide 10T.
Examples of the polyester include various aliphatic polyesters and various aromatic polyesters. Examples of the aliphatic polyester include polybutylene succinate, poly (butylene succinate-lactic acid) copolymer, and polyhydroxybutyric acid. Examples of the aromatic polyester include polyethylene terephthalate, polybutylene terephthalate, polyarylate, polybutylene adipate terephthalate, and the like. Furthermore, polycyclohexylenedimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate terephthalate, poly Butylene isophthalate choterephthalate, polyethylene terephthalate / cyclohexylene dimethylene terephthalate, cyclohexylene dimethylene isophthalate coterephthalate, copolyester composed of p-hydroxybenzoic acid residue and ethylene terephthalate residue, 1,3 which is a plant-derived raw material -Polytrimethylene terephthalate made of propanediol and the like.
The method for mixing the polylactic acid resin (A) and these resins is not particularly limited.

  Moreover, in the polylactic acid-type resin composition of this invention, if it is a range which does not impair the effect of this invention, the additive as shown below may further be contained. For example, end-capping agents, UV inhibitors, light stabilizers, anti-fogging agents, anti-fogging agents, antistatic agents, plasticizers, flame retardants, anti-coloring agents, antioxidants, fillers, pigments, mold release agents, moisture-proofing agents And various additives such as an oxygen barrier agent and a crystal nucleating agent. However, an additive containing a reactive functional group such as an epoxy group or an allyl group is not preferable. When such an additive is contained in the resin composition, the functional group reacts with the polylactic acid resin (A), and the polylactic acid resin (A) is easily gelled. When the polylactic acid resin (A) is gelled, a gelled portion is generated in the obtained molded product, and the quality is lowered and the transparency is easily lowered.

Next, the manufacturing method of the polylactic acid-type resin composition of this invention is demonstrated.
The method for producing the resin composition of the present invention is not particularly limited, and examples thereof include a melt kneading method that is industrially simplest. The resin composition of the present invention can be obtained by melt-kneading the polylactic acid resin (A), the polyalkylene ether (B), and the acrylic resin (C). In melt kneading, a general kneader such as a single screw extruder, a twin screw extruder, a roll kneader, or a Brabender can be used, and a twin screw extruder is used to improve the kneading state. It is preferable. The polyalkylene ether (B) and the acrylic resin (C) may be added from a separate feeder, or may be dry blended with the polylactic acid resin (A) and added from a hopper. A method of heating to a cylinder temperature of 180 to 230 ° C. and a die temperature of 190 to 240 ° C., melting and kneading these components and extruding, cooling the strand, and then cutting to a pellet size is preferable.

  In the production of the resin composition of the present invention, a master batch pellet in which the polyalkylene ether (B) and the acrylic resin (C) are added at a high concentration in the polylactic acid resin (A) is prepared. A method of obtaining a resin composition by diluting the master batch pellet with the polylactic acid resin (A) can also be employed. Specifically, after the master batch pellet and the polylactic acid resin (A) are dry blended, it is preferable to perform melt kneading with a single screw extruder or a twin screw extruder.

Next, the molded product of the present invention will be described.
The molded article of the present invention is molded using the polylactic acid resin composition of the present invention. Examples of the molding method include extrusion molding, injection molding, blow molding, inflation molding, injection blow molding, foamed sheet molding, and vacuum molding, pressure molding, and vacuum / pressure molding after sheet processing.

  As a molded body of the present invention, a film or sheet formed by extrusion molding, a molded body formed by processing these films or sheets, a molded body formed by injection molding, a molded body formed by bead foaming or extrusion foaming, blow molding And a molded body formed by processing the hollow body.

  Among these, the molded article of the present invention is preferably a sheet-shaped molded article taking advantage of the excellent transparency of the resin composition of the present invention. Specific examples of the sheet-like molded body include a sheet formed by extrusion molding and a film formed by stretching the sheet. The sheet formed by extrusion molding preferably has a thickness of about 10 to 500 μm, and the film formed by stretching the sheet preferably has a thickness of 200 μm or less.

Next, the manufacturing method of a sheet | seat or a film is demonstrated.
Examples of the sheet manufacturing method include a T-die method, an inflation method, and a calendar method. Of these, the T-die method and the inflation method are preferable. When producing a polylactic acid-based sheet by the T-die method, a polylactic acid-based resin composition prepared in advance may be supplied to the extruder hopper of the film forming apparatus, and the master batch pellet and the polylactic acid resin (A) May be supplied. The cylinder temperature of the extruder is preferably 150 to 250 ° C, and the T die temperature is preferably 160 to 250 ° C. Moreover, it is preferable that the cast roll is controlled at 20-50 degreeC.

Next, as a method for producing the film, a method of producing the polylactic acid-based sheet produced by the above method by uniaxially or biaxially stretching is preferable. Examples of the stretching method include a roll method and a tenter method, and it is preferable to employ any one of a uniaxial stretching method, a sequential biaxial stretching method, and a simultaneous biaxial stretching method. The surface magnification in stretching is preferably 4 to 16 times. If the surface magnification is less than 4, the mechanical properties of the resulting film, particularly the tensile strength, may be low and may not be practical. If the surface magnification exceeds 16 times, the film may not withstand the stretching stress during stretching and may break. The sheet temperature during stretching is preferably 50 to 110 ° C, more preferably 60 to 90 ° C. If the stretching temperature is less than 50 ° C., the film tends to break at the initial stage of stretching due to insufficient heat for stretching. On the other hand, when the temperature exceeds 110 ° C., heat is excessively applied to the film and draw stretching tends to occur, resulting in frequent stretching spots.
Moreover, you may give a thermal relaxation process after extending | stretching in order to provide dimensional stability to a stretched film. As a method of thermal relaxation treatment, a method of blowing hot air, a method of irradiating infrared rays, a method of irradiating microwaves, a method of contacting on a heat roll, etc. can be selected, and hot air is blown in that it can be heated uniformly and accurately. The method is preferred. In that case, it is preferable that it is 1 second or more in the range of 80-160 degreeC, and it is preferable to implement on the conditions of a 2-8% relaxation rate.

  Next, the present invention will be described specifically by way of examples. Measurement and evaluation of various characteristic values in the examples were performed as follows.

(1) Weight average molecular weight (Mw) of polylactic acid resin (A)
Using a gel permeation chromatography apparatus (manufactured by Shimadzu Corp.) equipped with a differential refractive index detector (manufactured by Shimadzu Corp., RID-10A), tetrahydrofuran (THF) as an eluent and a flow rate of 1.0 ml / min at 40 ° C. It was measured. As the column, SHODEX KF-805L and KF-804L (manufactured by Showa Denko KK) were connected and used. After dissolving 10 mg of the polylactic acid resin (A) in 0.5 ml of chloroform, the sample was diluted with 5 ml of THF and filtered through a 0.45 μm filter. The weight average molecular weight was converted using polystyrene (manufactured by Waters) as a standard sample.

(2) Melting point of polylactic acid resin (A) Using a differential scanning calorimeter (DSC device DSC7 manufactured by PerkinElmer), the polylactic acid resin (A) was heated from 20 ° C to 250 ° C at 20 ° C / min, Melting measured after holding for 5 minutes, cooling from 250 ° C. to 0 ° C. at 20 ° C./minute, holding at 0 ° C. for 5 minutes, and then re-heating from 0 ° C. to 250 ° C. at 20 ° C./minute The peak temperature (Tm) was taken as the melting point.

(3) Content of D-form of polylactic acid resin (A) About 0.3 g of polylactic acid resin (A) is added to 6 ml of 1N potassium hydroxide / methanol solution and sufficiently stirred at 65 ° C. to decompose the polylactic acid resin. Then, 450 μl of sulfuric acid was added and stirred at 65 ° C. to obtain methyl lactate. 5 ml of this sample, 3 ml of pure water, and 13 ml of methylene chloride were mixed and shaken. After stationary separation, about 1.5 ml of the lower organic layer was collected, filtered through a disk filter for HPLC (pore size 0.45 μm), and measured by gas chromatography.
Gas chromatography (Hewlett Packard, HP-6890) uses helium (He) as a carrier gas at a flow rate of 1.8 ml / min, an oven program held at 90 ° C. for 3 minutes, and at 50 ° C./min at 220 ° C. The temperature was raised up to 1 minute and maintained for 1 minute. The column was DB-17 (30 m × 0.25 mm × 0.25 μm) manufactured by J & W, and the detector was measured by FID (temperature 300 ° C.) and the internal standard method. The ratio (%) of the peak area of D-lactic acid methyl ester to the total peak area of lactate methyl ester was calculated, and this was used as the D-form content (mol%).

(4) Residual lactide amount of polylactic acid resin (A) 10 ml of dichloromethane and 0.5 ml of 2,6-dimethyl-γ-pyrone internal standard solution were added to 0.5 g of polylactic acid resin (A) and shaker (150 rpm × 40 minutes) and dissolved by stirring to prepare a sample solution for measurement. Cyclohexane was added thereto to precipitate a polymer, which was filtered through a disk filter for HPLC (pore size: 0.45 μm), and measured by gas chromatography. As the standard substance, L-lactide manufactured by Tokyo Chemical Industry Co., Ltd. was used.
Gas chromatography (Hewlett Packard, HP-6890) uses helium (He) as a carrier gas at a flow rate of 2.5 ml / min, an oven program held at 80 ° C. for 1 minute, and 20 ° C./min at 200 ° C. The temperature was raised to 280 ° C. at 30 ° C./min, and the conditions were maintained for 5 minutes. The column was DB-17 (30 m × 0.25 mm × 0.25 μm) manufactured by J & W, and the detector was measured by FID (temperature 300 ° C.) and the internal standard method.

(5) Melt viscosity of polylactic acid resin composition The melt viscosity was measured according to JIS K7210 using a Toyo Seiki Seisakusho melt indexer F-B01. The measurement was performed under the conditions of a test temperature of 190 ° C. and a test load of 2.16 kgf.

(6) Haze (transparency)
About the obtained sheet | seat and the stretched film, it measured using Nippon Denshoku Industries Co., Ltd. haze meter NDH2000 by JIS-K7105. At this time, the number of samples was set to 5, and the average value of these measured values was set as haze.

(7) Impact resistance of sheet Using the obtained sheet, a falling weight impact test was performed according to ASTM-2794, and the impact resistance strength was measured. That is, the breaking state was visually observed every five tests while changing the falling weight height (cm) with a falling weight of 300 gf and a striker of 1/8 inch.
Calculate the work amount by the formula of falling weight height (m) × falling weight 0.3 (kg) × 9.8 (m / s ² ) = work amount (J) when not destroyed at all. Impact strength was assumed.

(8) Impact resistance of film Using the obtained stretched film, a film impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used, and the pendulum capacity was 30 kgf on the stretched film fixed under tension in an atmosphere of 20 ° C. and 65% RH. A cm impact head (0.5 inch hemisphere) was hit and the energy required to penetrate the film was measured (ASTM D3420). And the impact strength was computed as the value which converted the thickness of the film into 100 micrometers. Those having an impact strength of 0.6 J / 100 μm or more were considered excellent in impact resistance.

Next, various raw materials used in Examples and Comparative Examples are shown.
(1) Polylactic acid resin (A)
A-1: Nature Works 4032D, D-form content 1.2 mol%, residual lactide amount 0.2 mass%, weight average molecular weight (Mw) 160,000, melting point 165 ° C
A-2: Nature Works 4042D, D-form content 4.0 mol%, residual lactide content 0.2 mass%, weight average molecular weight (Mw) 160,000, melting point 150 ° C.

(2) Polyalkylene ether (B)
B-1: Polyethylene glycol, Sanyo Chemical Industries PEG-20000, number average molecular weight (Mn) 20000
B-2: Polyethylene glycol, PEG-10000, Sanyo Chemical Industries, Ltd., number average molecular weight (Mn) 11000
B-3: Polyethylene glycol, Sanyo Kasei Kogyo PEG-6000S, number average molecular weight (Mn) 8300
B-4: Polyethylene glycol, PEG-4000S, Sanyo Chemical Industries, Ltd., number average molecular weight (Mn) 3400

(3) Acrylic resin (C)
C-1: Mitsubishi Rayon Co., Ltd. Metablen P-531A, weight average molecular weight 4.5 million C-2: Mitsubishi Rayon Co., Ltd. Metablen P-501A, weight average molecular weight 800,000 C-3: Mitsubishi Rayon Co., Ltd. Metablen P-700, weight Average molecular weight 500,000 C-4: Mitsubishi Rayon Co., Ltd. Metablen P-570A, weight average molecular weight 250,000

Example 1
[Polylactic acid resin composition]
Using 100 parts by mass of polylactic acid resin (A-1), 5 parts by mass of polyalkylene ether (B-1), and 5 parts by mass of acrylic resin (C-1) Extruder (Ikegai “PCM-30”, screw diameter: 29 mm, L / D (ratio of cylinder length L to diameter D of the extruder): 30, nozzle diameter: 4 mm, number of holes: 3, temperature: 230 ° C.) from the hopper. And after melt-kneading, it extruded, processed into the pellet form, and dried, and obtained the polylactic acid-type resin composition.
[Sheet]
The polylactic acid-based resin composition obtained as described above was melt-extruded at a T-die temperature of 230 ° C. with a single-screw extruder having a diameter of 90 mm, and was closely adhered to a cast roll whose temperature was controlled at 35 ° C. A sheet having a thickness of 250 μm molded with the resin composition of the invention was obtained.
[Stretched film]
The end of the obtained sheet was held by a clip of a tenter simultaneous biaxial stretching machine, and after running in a preheating zone at 81 ° C., it was 3.0 times MD and 3.3 times TD at a temperature of 79 ° C. Biaxial stretching was performed at the same magnification. Thereafter, after a heat treatment for 4 seconds at a temperature of 140 ° C. with a TD relaxation rate of 5%, the film was cooled to room temperature and wound up to obtain a stretched film having a thickness of 25 μm.

Examples 2-12, Comparative Examples 1-9
A polylactic acid resin composition was obtained in the same manner as in Example 1 except that the types and contents of the polyalkylene ether (B) and the acrylic resin (C) were changed as shown in Table 1. And the sheet | seat and the stretched film were manufactured like Example 1 using the obtained polylactic acid-type resin composition.

  Table 1 shows the compositions of the polylactic acid resin compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 9, and the characteristic values of the sheet and the stretched film.

As is clear from Table 1, the polylactic acid resin compositions obtained in Examples 1 to 12 were the contents of polyalkylene ether (B) and acrylic resin (C), and the acrylic resin (C). Since the weight average molecular weight was within the range of the present invention, the obtained sheet and stretched film were both excellent in transparency and impact resistance.
On the other hand, since the resin composition of Comparative Example 1 contained neither polyalkylene ether (B) nor acrylic resin (C), the obtained sheet and stretched film were inferior in impact resistance.
The resin composition of Comparative Example 2 contains a polyalkylene ether (B), but the weight average molecular weight of the acrylic resin (C) was outside the scope of the present invention. Also, the resin composition of Comparative Examples 3 and 4 Since the product did not contain the acrylic resin (C) or the content was too small, the obtained sheet and stretched film were both inferior in impact resistance. The resin composition of Comparative Example 5 was inferior in transparency because the content of the acrylic resin (C) was too large.
The resin compositions of Comparative Examples 6 and 7 contain the acrylic resin (C), but do not contain the polyalkylene ether (B) or the content is too small. It was inferior in impact resistance. Since the resin composition of Comparative Example 8 contained too much polyalkylene ether (B), the melt viscosity was low, and drawdown occurred when forming into a sheet, and the sheet could not be formed.
Since the resin composition of Comparative Example 9 contained too much polyalkylene ether (B) and acrylic resin (C), the resulting sheet and stretched film were both inferior in transparency.

Claims (2)

  A resin composition comprising a polylactic acid resin (A), a polyalkylene ether (B), and an acrylic resin (C) having a weight average molecular weight of 500,000 or more, and based on 100 parts by mass of the polylactic acid resin (A) 1 to 10 parts by mass of polyalkylene ether (B) and 0.3 to 10 parts by mass of acrylic resin (C). A sheet-like molded article obtained by molding the polylactic acid-based resin composition according to claim 1.