JP6513434B2 - Polylactic acid resin composition, sheet-like molded product comprising the same, and masterbatch pellet for polylactic acid resin composition - Google Patents

Description

  The present invention relates to a polylactic acid-based resin composition which is excellent in transparency and impact resistance, a sheet-like molded product comprising the resin composition, and a masterbatch pellet for a polylactic acid-based resin composition.

  It is desirable that films used as packaging materials for newspapers, magazines, foods, etc. be formed of biodegradable resins, with the recent increase in social demands for environmental protection. Among biodegradable resins, polylactic acid resin is widely present in the natural world, hardly harmful to animals and animals and animals, has a melting point of 140 to 175 ° C., has sufficient heat resistance, and has extremely high transparency. Since it is a relatively inexpensive thermoplastic resin and can be produced from plant-derived raw materials, it has attracted great attention.

  However, it has been difficult to use a sheet or film made of a polylactic acid resin in a field where impact resistance is required because it has a very hard and brittle property as it is.

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

  Further, Patent Document 3 discloses a resin composition containing a polylactic acid resin and a multilayer structure polymer. The resin composition is substantially added with at least 10% by mass of one type of multilayer structure polymer in order to improve impact resistance, flexibility and flex resistance. However, although this resin composition has a large content of the multilayer structure polymer and the impact resistance is improved, there is a problem that the transparency is lowered.

JP 2007-177140 A U.S. Pat. No. 6,495,631 Japanese Patent Application Publication No. 2003-286396

  The present invention solves the above-mentioned problems, and is a polylactic acid-based resin composition which is excellent in transparency and impact resistance and can be used also for food films and the like for which transparency is required, and sheet-like It is a technical task to provide a molded body.

  As a result of repeating researches to solve the above problems, the present inventors impair transparency by adding a specific amount of polytetramethylene ether glycol (B) having a specific molecular weight to the polylactic acid resin (A). It has been found that a polylactic acid-based resin composition excellent in impact resistance can be obtained, and the present invention has been achieved.

That is, the gist of the present invention is as follows.
(1) A resin composition comprising a polylactic acid resin (A) and a polytetramethylene ether glycol (B) having a number average molecular weight of 1200 or more, which is based on 100 parts by mass of the polylactic acid resin (A) A polylactic acid-based resin composition comprising 0.5 to 4.0 parts by mass of polytetramethylene ether glycol (B).
(2) Further, 0 parts by weight of acrylic polymer (C) per 100 parts by mass of polylactic acid resin (A)
. The polylactic acid-based resin composition according to (1), which contains 1 to 3 parts by mass.
(3) Furthermore, at least one selected from polyalkylene ether (E) other than glycerin fatty acid ester (D) and polytetramethylene ether glycol is used in an amount of 0.1 to 3 with respect to 100 parts by mass of polylactic acid resin (A) The polylactic acid-type resin composition as described in (1) or (2) which contains a mass part.
(4) The sheet-like molded object which consists of a polylactic acid-type resin composition in any one of (1)-(3).
(5) A resin composition containing a polylactic acid resin (A) and a polytetramethylene ether glycol (B) having a number average molecular weight of 2000 or more, which is based on 100 parts by mass of the polylactic acid resin (A) A masterbatch pellet for a polylactic acid-based resin composition comprising 2 to 30 parts by mass of polytetramethylene ether glycol (B).

  The polylactic acid-based resin composition of the present invention is a polylactic acid resin (A) to which a specific amount of polytetramethylene ether glycol (B) is added, and therefore the high transparency inherent in the polylactic acid resin was maintained. In addition, impact resistance is improved. Therefore, it is suitable to use the polylactic acid-based resin composition of the present invention particularly for applications such as films and sheets. And since the sheet-like compact | molding | casting of this invention is shape | molded from the polylactic acid-type resin composition of this invention, it is excellent in transparency and impact resistance, For foodstuffs and industrials for which transparency is calculated | required. It can be used for film applications.

Hereinafter, the present invention will be described in detail. First, the polylactic acid resin (A) will be described.
As polylactic acid resin (A) in the present invention, 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, L-lactic acid and D-lactic acid A polymer, poly-DL-lactic acid, or a mixture thereof can be mentioned.

In the present invention, any of a crystalline polylactic acid resin and an amorphous polylactic acid resin may be used as the polylactic acid resin (A), but the operability when obtaining a molded product, and the heat resistance to the molded product are further provided. It is preferable to use crystalline polylactic acid resin in consideration of the problem.
Here, the crystalline polylactic acid resin refers to a polylactic acid resin having a melting point in the range of 140 ° C. 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) into a crystalline polylactic acid resin, the D-form content in the polylactic acid resin (A) is preferably 5 mol% or less, and in particular, the D-form content is 4 mol% It is preferable to set it as the following, and also it is preferable to make D-form content into 2 mol% or less. If the D-form content exceeds 5 mol%, the crystallinity of the polylactic acid resin is reduced, and it is necessary to add a crystal nucleating agent, or if it does not contain a crystal nucleating agent, sufficient heat treatment is performed. The crystallization does not occur, the operability at the time of obtaining a molded product is lowered, and the obtained molded product tends to be inferior in heat resistance.

  When polytetramethylene ether glycol (B) is 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 effect is reduced, and further, the impact resistance imparting effect by the addition of the polytetramethylene ether glycol (B) is further improved. It becomes a thing.

  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 article tends to be inferior in mechanical properties. On the other hand, when the weight average molecular weight exceeds 300,000, the melt viscosity becomes too high, and melt extrusion at the time of obtaining a molded product tends to be difficult.

  Further, 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, and most preferably 0.1% by mass or less preferable. When the amount of residual lactide exceeds 0.5% by mass, when forming a molded product, for example, when forming a sheet or a film, smoke is extremely generated and the device in the vicinity of the die is contaminated to lower the product quality or the operation Also easy to fall. Furthermore, the obtained molded product may be inferior in durability and the like.

  The polylactic acid-based resin composition of the present invention contains the polylactic acid resin (A) as a main component, and the content of the polylactic acid resin (A) is 80% by mass or more of the entire resin composition Preferably, it is 90% by mass or more, and more preferably. It is most preferable that it is 95 mass% or more. When the content of the polylactic acid resin (A) is small, the transparency of the resin composition is reduced, and the amount of the biodegradable resin used is reduced, so that it can not 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 of polylactic acid resins can also be used in combination. Further, lactide, which is a cyclic dimer of lactic acid, can be used as a raw material, and one produced by a known melt polymerization method or additionally using a solid phase polymerization method can be used.

Next, polytetramethylene ether glycol (B) will be described.
In the present invention, the polytetramethylene ether glycol (B) needs to have a number average molecular weight of 1200 or more, and among them, the number average molecular weight is preferably 1500 or more, and more preferably 2000 or more. More preferable. When the number average molecular weight is less than 1200, the effect of improving the impact resistance tends to be insufficient, and bleed out or processing may be deteriorated.

The content of polytetramethylene ether glycol (B) is polylactic acid resin (A) 100
Relative to the weight section, Ru necessary der to be 0.5 to 4.0 parts by weight. When the content of the polytetramethylene ether glycol (B) is less than 0.1 parts by mass, the above-described impact resistance improvement effect becomes insufficient. On the other hand, when the content of the polytetramethylene ether glycol (B) exceeds 5.0 parts by mass, the transparency of the obtained resin composition is lowered .

The resin composition of the present invention is a polylactic acid resin (A) and a polytetramethylene ether glycol (B), in addition to an acrylic polymer (C), a glycerin fatty acid ester (D) and a polyother than polytetramethylene ether glycol. It is preferable to contain at least one selected from alkylene ether (E). These, when used in combination with polytetramethylene ether glycol (B), have the effect of further improving the impact resistance. Among them, it is preferable to contain an acrylic polymer (C) since it is excellent in the impact resistance improvement effect.
In particular, the acrylic polymer (C) not only improves the impact resistance but also seems to improve the compatibility between the polylactic acid resin (A) and the polytetramethylene ether glycol (B), although the principle is not understood. . Therefore, it plays a very important role in the resin composition of the present invention.
Therefore, in the polylactic acid-based resin composition of the present invention, when the acrylic polymer (C) is contained, the content of the polytetramethylene ether glycol (B) is the polylactic acid resin (
A) 0.1 to 3.0 parts by mass is preferable with respect to 100 parts by mass, and in particular 0.2
It is preferable that it is -2.5 mass parts.

First, the acrylic polymer (C) will be described.
The acrylic polymer (C) is preferably at least one of the core-shell type graft copolymer (C1) and the (meth) acrylate polymer (C2).
First, the core-shell type graft copolymer (C1) will be described. The core-shell type graft copolymer (C1) is composed of a core layer and a shell layer covering it, and adjacent layers are composed of different polymers. The core layer and the shell layer may each have a plurality of layers. The core-shell type graft copolymer (C1) is preferably obtained by graft polymerization of the shell layer component in the presence of the core layer component.

  In the present invention, the core layer of the core-shell type graft copolymer (C1) is preferably either an acrylic rubber or a silicone rubber from the viewpoint of improving the impact resistance, and among them an acrylic from the viewpoint of transparency. Particular preference is given to rubbers.

The acrylic rubber that forms the core component preferably contains 50 to 100% by mass, and more preferably 70 to 100% by mass of the acrylic ester as the main constituent unit. It is preferable that components other than acrylic acid ester in acrylic type rubber are vinyl-type monomers copolymerizable with acrylic acid ester.
As an acrylic ester which comprises acrylic rubber, the acrylic acid alkylester which has C2-C8 of an alkyl group is mentioned, For example, an ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate etc. are mentioned.

  Examples of vinyl monomers copolymerizable with acrylic acid esters include aromatic vinyl compounds such as styrene and α-methylstyrene, methacrylic acid alkyl esters such as methyl methacrylate and ethyl methacrylate, unsaturation such as acrylonitrile and methacrylonitrile Nitriles, vinyl ethers such as methyl vinyl ether and butyl vinyl ether, vinyl halides such as vinyl chloride and vinyl bromide, vinylidene halides such as vinylidene chloride and vinylidene bromide, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, ethylene glycol glycidyl ether, etc. And vinyl monomers having a glycidyl group of

  The silicone rubber forming the core component is a rubber containing polyorganosiloxane which is a linear polymer having several thousands or more of organosiloxane bond units, and contains polyorganosiloxane and alkyl (meth) acrylate rubber. Containing silicone and acrylic rubber. Although the above rubber may be produced by any method, the emulsion polymerization method is optimum.

  The structure of the polyorganosiloxane is not particularly limited, but is preferably a polyorganosiloxane containing a vinyl polymerizable functional group. As a dimethylsiloxane used for manufacture of polyorganosiloxane, a 3- or more-membered dimethylsiloxane cyclic body is mentioned, The thing of a 3- to 7-membered ring is preferable. Specifically, hexamethyl cyclotrisiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, dodecamethyl cyclohexasiloxane etc. are mentioned, These are used individually or in mixture of 2 or more types.

  In the present invention, the shell component constituting the core-shell type graft copolymer (C1) is an unsaturated carboxylic acid alkyl ester unit, a glycidyl group-containing vinyl unit, an aliphatic vinyl unit, an aromatic vinyl unit, vinyl cyanide The polymer is preferably formed of a polymer containing a system unit, a maleimide unit, an unsaturated dicarboxylic acid unit, an unsaturated dicarboxylic anhydride unit and / or another vinyl unit. Among them, a polymer containing an unsaturated carboxylic acid alkyl ester unit, a glycidyl group-containing vinyl unit and / or an unsaturated dicarboxylic acid anhydride unit is preferable, and a polymer further containing an unsaturated carboxylic acid alkyl ester unit Is more preferred.

  As the unsaturated carboxylic acid alkyl ester-based unit constituting the polymer of the shell component, (meth) acrylic acid alkyl ester is preferably used. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic N-hexyl acid, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, octadecyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate (( (Meth) acrylic acid chloromethyl, (meth) acrylic acid 2-chloroethyl, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2,3,4,5,6 -Pentahydroxyhexyl, 2,3,4,5-tetrahydroxypentyl (meth) acrylic acid, acrylic acid amide Ethyl, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate and the like can be mentioned, and from the viewpoint of having a large effect of improving the dispersibility in the resin Methyl (meth) acrylate and n-butyl (meth) acrylate are preferably used. These units may be used alone or in combination of two or more.

  The glycidyl group-containing vinyl-based unit constituting the polymer of the shell component is not particularly limited, and glycidyl (meth) acrylate, glycidyl itaconate, diglycidyl itaconate, allyl glycidyl ether, styrene-4-glycidyl ether 4-glycidyl styrene etc. is mentioned and glycidyl (meth) acrylate is preferably used from a viewpoint that the effect of improving impact resistance is large. These units may be used alone or in combination of two or more.

  Ethylene, propylene, butadiene etc. are mentioned as an aliphatic vinyl type unit which comprises the polymer of a shell component. As the aromatic vinyl-based unit, styrene, α-methylstyrene, 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, -(Phenyl butyl) styrene, halogenated styrene, etc. are mentioned. Examples of the vinyl cyanide-based unit include acrylonitrile, methacrylonitrile, ethacrylonitrile and the like. As a maleimide-based unit, maleimide, N-methyl maleimide, N-ethyl maleimide, N-propyl maleimide, N-isopropyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, N- (p-bromophenyl) maleimide, N- (Chlorophenyl) maleimide and the like. Examples of unsaturated dicarboxylic acid units include maleic acid, monoethyl ester of maleic acid, itaconic acid and phthalic acid.

  As other vinyl units constituting the polymer of the shell component, acrylamide, methacrylamide, N-methyl acrylamide, butoxymethyl acrylamide, N-propyl methacrylamide, N-vinyldiethylamine, N-acetylvinylamine, allylamine, meta Examples include allylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline, 2-styryl-oxazoline and the like. These units may be used alone or in combination of two or more.

Among the core-shell type graft copolymers (C1) in which the core layer and the shell layer as described above are combined, the core layer is made of an acrylic rubber and the shell layer is made of a polymer containing unsaturated carboxylic acid alkyl ester units Is preferable because the impact resistance improvement effect is excellent. Among them, the shell layer grafts one or more kinds of unsaturated carboxylic acid alkyl ester units, especially methyl (meth) acrylate, to the acrylic rubber of the core layer in the presence of the acrylic rubber of the core layer. It is preferable that it is obtained by polymerizing.
As commercial products of the core-shell type graft copolymer (C1) of the combination as described above, Paraloid BPM-500, Paraloid BPM-515, Metabrene W-450A, Metabrene W-600A, etc. It can be mentioned.

  Next, the (meth) acrylic acid ester-based polymer (C2) will be described. As a monomer which comprises a (meth) acrylic acid ester type polymer, acrylic acid, its ester, methacrylic acid, and its ester are mentioned, for example. These monomers may be used alone or in combination of two or more. As a copolymer, a block copolymer, a random copolymer, a graft copolymer, or these combination is mentioned, for example.

Specific examples of (meth) acrylic acid and esters thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, 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, trifluoro (meth) acrylate Ethyl, (meth) heptadecafluorooctyl acrylate, isobornyl (meth) acrylate, and (meth) adamantyl acrylate and (meth) tricycloalkyl Desi sulfonyl acrylate. In addition, monomers such as styrene, α-methylstyrene, t-butylstyrene, and substituted styrene such as chlorostyrene may be copolymerized.
The (meth) acrylic acid ester-based copolymer may be produced using a known method.

As a first preferred embodiment of the (meth) acrylate polymer (C2), there may be mentioned ultrahigh molecular weight (meth) acrylate polymers having a weight average molecular weight of 500,000 to less than 10,000,000. By using an ultrahigh molecular weight (meth) acrylic acid ester-based polymer having a weight average molecular weight in the above range, impact resistance is significantly improved and flexibility is improved. If the weight average molecular weight is less than 500,000, the effect of improving impact resistance and flexibility can not be sufficiently obtained. On the other hand, when the weight average molecular weight exceeds 10,000,000, there arises a problem that the compatibility of the obtained resin composition is impaired or the melt viscosity becomes too high to be difficult to handle.
The weight average molecular weight of such (meth) acrylic acid ester-based polymer is more preferably 800,000 to 8,000,000, and still more preferably 1,000,000 to 5,000,000.

  As a commercial item of the (meth) acrylic acid ester polymer of the first preferred embodiment described above, for example, methabrene P series manufactured by Mitsubishi Rayon, PARALOID K series manufactured by Rohm and Haas, and Kaneka Kane ace PA series is mentioned.

As a 2nd preferable aspect of a (meth) acrylic-ester type polymer, the block copolymer (it represents as block copolymer P hereafter) of methyl methacrylate and n-butyl acrylate is mentioned. By using this block copolymer P, impact resistance is significantly improved, and flexibility and impact resistance to falling ball impact and falling weight impact are also enhanced.
Since the effect of improving the flexibility and impact resistance is sufficiently obtained, the proportion of n-butyl acrylate in the monomers constituting the block copolymer P is preferably 60% by mass or more, 75 mass% or more is more preferable.
The block copolymer P has a molecular chain composed of a hard block consisting of 1 to 5 methyl methacrylate units and a soft block consisting of 1 to 5 n-butyl acrylate units Is preferred.

  The hard block consisting of methyl methacrylate units in the molecular chain of the block copolymer P contributes to good compatibility with the polylactic acid resin (A) and the polytetramethylene ether glycol (B). The soft block consisting of n-butyl acrylate units in the molecular chain of the block copolymer P contributes to the improvement of the flexibility and the impact resistance.

  As a commercial item of the block copolymer P of the second preferred embodiment, for example, trade name “Klarity LA 2140 e” (content of n-butyl acrylate is 77% by mass) manufactured by Kuraray Co., Ltd., trade name manufactured by Kuraray Co., Ltd. "CLARITY LA2250" (The content of n-butyl acrylate is 67% by mass).

The content of the acrylic polymer (C) in the polylactic acid-based resin composition of the present invention is 100 parts by mass of the polylactic acid resin (A), considering the effect of imparting impact resistance to the resin composition. 0.1-3.0 mass parts is preferable, 0.3-2.8 mass parts is more preferable, 0.5-2.5 mass parts is especially preferable.
If the content of the acrylic polymer (C) is less than 0.1 parts by mass, the effect of improving the impact resistance can not be obtained. On the other hand, when the content of the acrylic polymer (C) exceeds 3.0 parts by mass, the transparency is lowered and the cost is disadvantageous.

Next, glycerine fatty acid ester (D) will be described.
Examples of glycerin fatty acid ester (D) include monoglyceride, diglyceride, triglyceride, diglycerin fatty acid ester, polyglycerin fatty acid ester and the like.
Examples of the fatty acid in monoglycerides, diglycerides, triglycerides and diglycerin fatty acid esters include lauric acid, undecylenic acid, glyceryl myristate, stearic acid, isostearic acid, oleic acid and the like.

Further, as polyglyceryl fatty acid esters, polyglyceryl monostearate, polyglyceryl monooleate, polyglyceryl monolaurate, polyglyceryl monoisostearate, polyglyceryl monocaprylate, polyglyceryl monocaprate, polyglyceryl monomyristate, polyglyceryl polyricinolenoate, distearin Polyglyceryl acid, polyglyceryl diisostearate, polyglyceryl tristearate, (diisostearic acid / polyhydroxystearic acid / sebacic acid) polyglyceryl, sorbitan monolaurate, sorbitan monooleate, sorbitan sesquioleate, sorbitan fatty acid esters such as sorbitan trioleate, etc. , Polyhydroxystearic acid, castor oil fatty acid condensate, 1,2-hydride Higher fatty acid derivatives such as roxy stearic acid condensates can be mentioned.
Among them, preferred are polyglycerin fatty acid esters of diglycerin furstearate and mixtures of caprylic acid, capric acid and lauric acid.

The content of the glycerin fatty acid ester (D) in the polylactic acid-based resin composition of the present invention is 100 parts by mass of the polylactic acid resin (A), in consideration of the effect of imparting impact resistance to the resin composition. 0.1-3.0 mass parts is preferable, 0.3-2.8 mass parts is more preferable, 0.5-2.5 mass parts is especially preferable.
When the content of the glycerin fatty acid ester (D) is less than 0.1 parts by mass, the effect of improving the impact resistance can not be obtained. On the other hand, when the content of the glycerin fatty acid ester (D) exceeds 3.0 parts by mass, the transparency is lowered and the melt viscosity is further lowered too much.

Next, polyalkylene ethers (E) other than polytetramethylene ether glycol will be described.
In the present invention, as the polyalkylene ether (E) other than polytetramethylene ether glycol , polyethylene glycol, polypropylene glycol and the like can be mentioned, and the compatibility with the polylactic acid resin (A) is good and the transparency is maintained. Polyethylene glycol is preferred because the effect is also high.

In the present invention, the number average molecular weight of the polyalkylene ether (E) other than polytetramethylene ether glycol is preferably 5,000 or more, more preferably 7,000 or more, and further preferably 8,000 to 30,000. preferable. If the number average molecular weight is less than 5,000, the effect of improving the impact resistance tends to be insufficient, and bleed out or processing may be impaired. On the other hand, when the number average molecular weight exceeds 30,000, the compatibility with the polylactic acid resin (A) may be lowered, and the impact resistance improvement effect may be insufficient.

The content of the polyalkylene ether (E) other than polytetramethylene ether glycol is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A), and more preferably 0.3 to 2 The amount is preferably 8 parts by mass, and more preferably 0.5 to 2.5 parts by mass. If the content of the polyalkylene ether (E) other than polytetramethylene ether glycol is less than 0.1 parts by mass, the effect of improving the impact resistance can not be obtained. On the other hand, when the content of the polyalkylene ether (E) other than polytetramethylene ether glycol exceeds 3 parts by mass, the transparency of the obtained resin composition is lowered, and the melt viscosity is too low.

When the polylactic acid-based resin composition of the present invention is used in combination with an acrylic polymer (C), a glycerin fatty acid ester (D), or a polyalkylene ether (E) other than polytetramethylene ether glycol , the total of these The content of is preferably 0.1 to 3 parts by mass, more preferably 0.3 to 2.8 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A). It is more preferable that it is -2.5 mass parts. If the total content of these is less than 0.1 parts by mass, the effect of improving the impact resistance can not be obtained. On the other hand, when the total content of these components exceeds 3 parts by mass, the transparency of the obtained resin composition is lowered and the melt viscosity is excessively lowered.

The polylactic acid-based resin composition of the present invention preferably has an appropriate melt viscosity so as to obtain a sheet or film with good moldability. That is, the melt flow rate (hereinafter sometimes referred to as MFR) is preferably 0.1 to 100 g / 10 min, and more preferably 1.0 to 20 g / 10 min, and more preferably 2.5 to 2.5 g / 10 min. Most preferably, it is 8.5 g / 10 min.
When the MFR is less than 0.1 g / 10 min, extrusion becomes difficult at the time of kneading at the time of molding processing or sheeting. On the other hand, if the MFR exceeds 100/10 minutes, the melt viscosity is too low to draw down, making sheet formation difficult.

  When the polylactic acid-based resin composition of the present invention is used, a molded article excellent in transparency and impact resistance can be obtained. Among 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 (the measurement method is described in the examples described later), which is an index indicating transparency, is 10% or less Is possible. Above all, the haze value is preferably 7% or less, and more preferably 6% or less. A sheet having a haze value of more than 10% is inferior in transparency, and when used as a packaging material, for example, it becomes difficult to confirm the contents.

  Moreover, in the case of a stretched film with a thickness of 10 to 100 μm, the haze value can be 5% or less. Above all, the haze value is preferably 4% or less, more preferably 3% or less. When the film has a haze value of more than 4%, the film is inferior in transparency. For example, when the film is used in a packaging material, it is difficult to confirm the contents.

  Among 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, the impact strength (the measurement method will be described in the examples described later), which is an index showing impact resistance, It is possible to do more than. Among them, the impact strength is preferably 0.4 J or more, and more preferably 0.5 J or more.

  In addition, in the polylactic acid-type resin composition of this invention, as long as the effect is not impaired, you may contain resin other than polylactic acid resin (A).

Such other resins include polyolefins, polyesters, polyamides, polycarbonates, polystyrenes, polymethyl (meth) acrylates, poly (acrylonitrile-butadiene-styrene) copolymers, liquid crystal polymers, polyacetals and the like.
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, polyamide 10T and the like.

Examples of polyesters include various aliphatic polyesters, various aromatic polyesters, and many others. Examples of aliphatic polyesters include polybutylene succinate, poly (butylene succinate-lactic acid) copolymer, and polyhydroxy butyric acid. Examples of the aromatic polyester include polyethylene terephthalate, polybutylene terephthalate, polyarylate, polybutylene adipate terephthalate, etc. Further, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate co-terephthalate, poly Butylene isophthalate co-terephthalate, polyethylene terephthalate / cyclohexylene dimethylene terephthalate, cyclohexylene dimethylene isophthalate co-terephthalate, copolyester comprising p-hydroxybenzoic acid residue and ethylene terephthalate residue, plant-derived raw materials 1, 3 -Polytrimethylene terephthalate etc. which consist of propanediol etc. are mentioned.
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 blocking agents, UV inhibitors, light stabilizers, antifogging agents, antifog agents, antistatic agents, plasticizers, flame retardants, flame retardants, coloring inhibitors, antioxidants, fillers, pigments, mold release agents, moisture proofing agents And various additives such as an oxygen barrier agent and a crystal nucleating agent. However, additives containing a functional group having reactivity such as epoxy group and allyl group are 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) tends to gel. When the polylactic acid resin (A) is gelled, a gelled part is formed in the obtained molded product, and the quality is lowered and the transparency is also easily lowered.

Next, the method for producing the polylactic acid-based resin composition of the present invention will be described.
Although the method to manufacture the resin composition of this invention is not specifically limited, For example, the melt-kneading method most industrially simple is mentioned. The case of melt-kneading the polylactic acid resin (A) and the polytetramethylene ether glycol (B) will be described. In melt-kneading, general kneaders such as single-screw extruders, twin-screw extruders, roll kneaders, Brabender and the like can be used, and a twin-screw extruder is used to improve the kneading state. Is preferred. The polytetramethylene ether glycol (B) may be melted and added by pouring, or crushed and added from another feeder, or it may be dry blended with the polylactic acid resin (A) and added from the hopper Good. It is preferable to heat to a cylinder temperature of 180 to 230 ° C. and a die temperature of 190 to 240 ° C., melt-knead and extrude these components, and cool the strand and cut it into a pellet size.

  Moreover, in the case of manufacture of the resin composition of this invention, the masterbatch pellet by which polytetramethylene ether glycol (B) was added in high concentration in polylactic acid resin (A) is produced, This masterbatch pellet is polylactic acid. A method of obtaining a resin composition can also be employed by diluting with the resin (A). Specifically, after dry blending of the masterbatch pellets and the polylactic acid resin (A), it is preferable to perform melt-kneading using a single screw extruder or a twin screw extruder.

Next, the molded article of the present invention will be described.
The molded object of this invention is shape | molded using the polylactic acid-type resin composition of this invention. Examples of molding methods include extrusion molding, injection molding, blow molding, inflation molding, injection blow molding, foam sheet molding, and vacuum forming after sheet processing, pressure forming, vacuum pressure forming, and the like.

  As the molded product of the present invention, a film or sheet formed by extrusion molding, a molded product formed by processing the film or sheet, a molded product formed by injection molding, a molded product formed by bead foaming or extrusion foaming, blow molded Hollow bodies, molded articles obtained by processing the hollow bodies, and the like.

  Above all, the molded article of the present invention is preferably a sheet-like molded article, taking advantage of the excellent transparency of the resin composition of the present invention. As a specific example of a sheet-like molded object, the sheet | seat (unstretched sheet | seat) formed by extrusion molding and the film formed by extending | stretching this sheet | seat are mentioned. The sheet formed by extrusion molding preferably has a thickness of about 100 to 500 μm, and the film formed by stretching the sheet preferably has a thickness of 100 μm or less.

Next, a method of producing a sheet or film will be described.
Examples of the method for producing the sheet include a T-die method, an inflation method, a calendar method and the like. Among them, the T-die method and the inflation method are preferable. When producing a polylactic acid-based sheet by the T-die method, the polylactic acid-based resin composition prepared in advance may be supplied to the extruder hopper of a film forming apparatus, and a masterbatch pellet and a polylactic acid resin (A) May be supplied. It is preferable that the cylinder temperature of an extruder is 150-250 degreeC, and T-die temperature is 160-250 degreeC. Moreover, it is preferable that the cast roll is controlled by 20-50 degreeC.

  Next, as a method of producing a film, a method of uniaxially or biaxially stretching a polylactic acid-based sheet produced by the above method is preferred. As a stretching method, a roll method, a tenter method, etc. may be mentioned, and it is preferable to adopt any of a uniaxial stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method. It is preferable that the surface magnification in extending | stretching is 4 to 16 times. When the area magnification is less than 4 times, the mechanical properties of the resulting film, in particular, the tensile strength, may be low and it may not be practical. In addition, when the area ratio exceeds 16 times, the film may not withstand the stretching stress during the stretching and may be broken. 50-110 degreeC is preferable and 60-90 degreeC of sheet | seat temperature at the time of extending | stretching is more preferable. If the stretching temperature is less than 50 ° C., the film tends to break at the initial stage of stretching due to the lack of heat for stretching. When the temperature exceeds 110 ° C., heat is applied to the film to make it draw draw, which tends to cause stretching spots frequently.

  Further, for the purpose of imparting dimensional stability to the stretched film, a heat relaxation treatment may be applied after stretching. 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 the hot air is blown in that it can be heated uniformly and precisely. 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 2-8% of a relaxation rate.

Next, the polylactic acid-based masterbatch pellet of the present invention (hereinafter sometimes abbreviated as masterbatch pellet) will be described. It is preferable to use the masterbatch pellet of this invention, when manufacturing the polylactic acid-type resin composition of this invention.
In many cases, polytetramethylene ether glycol (B) is massive, and it is difficult to add a precise amount, for example, by grinding and adding, or melting and adding it to liquid injection and adhering to an apparatus. Therefore, in the production of the polylactic acid-based resin composition of the present invention, a masterbatch pellet in which polytetramethylene ether glycol (B) is added at a high concentration in the polylactic acid resin (A) is produced, and this masterbatch It is preferable to adopt a method of obtaining a polylactic acid-based resin composition by diluting the pellet with the polylactic acid resin (A).

Therefore, the masterbatch pellet of the present invention is composed of a resin composition containing a polylactic acid resin (A) and a polytetramethylene ether glycol (B).
The content of the polytetramethylene ether glycol (B) is 2 to 30 parts by mass, preferably 4 to 28 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A).
When the content of polytetramethylene ether glycol (B) is less than the above range, the amount of master batch pellets used increases when obtaining the polylactic acid resin composition of the present invention, and polytetramethylene ether glycol (B) It can not be said to be a masterbatch pellet containing a high concentration of On the other hand, when the content of the polytetramethylene ether glycol (B) is more than the above range, the operability at the time of producing the masterbatch pellet is lowered, and the dispersibility of the polytetramethylene ether glycol (B) is lowered. Uneven density occurs in the masterbatch pellets.

Next, a method for producing the polylactic acid-based resin composition of the present invention by diluting the polylactic acid resin (A) after producing the masterbatch pellet of the present invention as described above will be described.
First, the method for producing a masterbatch pellet of the present invention will be described. In the extruder, polylactic acid resin (A) and polytetramethylene ether glycol (B) are added and melt-kneaded. At this time, melt kneading is performed with a single screw extruder or a twin screw extruder, heated to a cylinder temperature of 180 to 230 ° C., and a die temperature of 190 to 240 ° C., the resin composition is melt kneaded and extruded, and the strand is cooled. The method of cutting into pellet size is preferable. The extruder used is preferably a twin-screw extruder in view of the kneading capacity. In addition, it is preferable that the polylactic acid resin (A) is supplied from a hopper, and the polytetramethylene ether glycol (B) is added by pouring while heating. When adding polytetramethylene ether glycol (B) in a single screw extruder or a twin screw extruder, it is preferable to carry out from a supply part side rather than one half of the whole kneading part. For example, when the kneading part is divided into 11 parts from C1 part (supply side) to C11 part (die side), adding polytetramethylene ether glycol (B) between C1 part to C5 part preferable. The dispersibility of the polytetramethylene ether glycol (B) is not low, but when it is added from a half or more of the entire kneading part, the dispersibility of the polytetramethylene ether glycol (B) becomes low, and the obtained masterbatch Uneven concentration is likely to occur in the pellet. When such a masterbatch pellet is used, the resulting polylactic acid-based resin composition also has uneven concentration, which tends to cause variations in the physical properties of the obtained molded article.

  The polylactic acid-based resin composition of the present invention uses the masterbatch pellet obtained as described above, and the polylactic acid resin (A) is made to have a desired concentration of polytetramethylene ether glycol (B). Can be obtained by dilution with

The masterbatch pellet of the present invention comprises, in addition to the polylactic acid resin (A) and the polytetramethylene ether glycol (B), an acrylic polymer (C) and a glycerin fatty acid ester (D)
And at least one polyalkylene ether (E) other than polytetramethylene ether glycol .
The content of the acrylic polymer (C), glycerin fatty acid ester (D) and polyalkylene ether (E) other than polytetramethylene ether glycol in the masterbatch pellet is two types when using any one of them. When using together the above, it is preferable to contain 5-60 mass parts with respect to 100 mass parts of polylactic acid resin (A).

When at least one of an acrylic polymer (C), a glycerin fatty acid ester (D) and a polyalkylene ether (E) other than polytetramethylene ether glycol is added, the acrylic polymer (C) in the above production method And polyalkylene ethers (E) other than polytetramethylene ether glycol are preferably metered and added by separate feeders. The glycerin fatty acid ester (D) is often in the form of a liquid or a low melting substance, so it is preferable to mix it with the polytetramethylene ether glycol (B) and add it to the solution or add it separately. .

  Next, the present invention will be specifically described 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 Corporation) equipped with a differential refractive index detector (manufactured by Shimadzu Corporation, RID-10A), using tetrahydrofuran (THF) as an eluent, at a flow rate of 1.0 ml / min at 40 ° C. It was measured. As columns, SHODEX KF-805L and KF-804L (manufactured by Showa Denko KK) were connected and used. After dissolving 10 mg of polylactic acid resin (A) in 0.5 ml of chloroform, it was diluted with 5 ml of THF, and the sample filtered through a 0.45 μm filter was used for measurement. The weight average molecular weight was converted using polystyrene (manufactured by Waters) as a standard sample.

(2) Melting point of polylactic acid resin (A) The polylactic acid resin (A) is heated from 20 ° C. to 250 ° C. at a rate of 20 ° C./min using a differential scanning calorimeter (DSC apparatus DSC7 manufactured by Perkin Elmer). After holding for 5 minutes, it is cooled at 20 ° C./min from 250 ° C. to 0 ° C., held at 0 ° C. for 5 minutes, and further measured by reheating from 0 ° C. to 250 ° C. at 20 ° C./min. The peak temperature (Tm) was taken as the melting point.

(3) D-form content 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 polylactic acid resin After the addition, 450 μl of sulfuric acid was added and the mixture was stirred at 65 ° C. to obtain lactic acid methyl ester. 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 with a disk filter for HPLC (pore diameter 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 is held at 90 ° C. for 3 minutes, and 50 ° C./min at 220 ° C. The temperature was raised until the temperature was maintained for 1 minute. As a column, DB-17 (30 m × 0.25 mm × 0.25 μm) manufactured by J & W Inc. was used, and a detector was measured by FID (temperature 300 ° C.) by an internal standard method. The ratio (%) of the peak area of D-lactic acid methyl ester to the total peak area of lactic acid methyl ester was calculated, and this was taken as the D-form content (mol%).

(4) Amount of residual lactide of polylactic acid resin (A) To 0.5 g of polylactic acid resin (A), 10 ml of dichloromethane and 0.5 ml of 100 ppm 2,6-dimethyl-γ-pyrone internal standard solution were added and shaken (150 rpm × The solution was stirred and dissolved for 40 minutes to prepare a sample solution for measurement. Thereto, cyclohexane was added to precipitate a polymer, which was filtered with a disk filter for HPLC (pore diameter 0.45 μm) and measured by gas chromatography. As a 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 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. As a column, DB-17 (30 m × 0.25 mm × 0.25 μm) manufactured by J & W Inc. was used, and a detector was measured by FID (temperature 300 ° C.) by an internal standard method.

(5) MFR of polylactic acid resin composition
It measured based on JISK7210 using Toyo Index Co., Ltd. product melt indexer F-B01. It measured on the conditions of test temperature 190 degreeC and test load 2.16kgf.

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

(7) Impact Resistance Using the obtained sheet, a drop weight impact test was performed according to ASTM-2794 to measure the impact resistance strength. That is, while changing the falling weight height (cm) with a falling weight of 300 gf and a shooting point of 1/8 inch, the broken state every five times of the test was visually observed.
The amount of work is calculated by the formula of drop weight height (m) x drop weight 0.3 (kg) x 9.8 (m / s ² ) = work amount (J) when not destroyed at all Impact resistance.

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

(2) Polytetramethylene ether glycol (B)
B-1: Mitsubishi Chemical Corporation PTMG 3000, number average molecular weight (Mn) 3000
B-2: Mitsubishi Chemical Corporation PTMG 2000, number average molecular weight (Mn) 2000
B-3: Mitsubishi Chemical Corporation PTMG 1000, number average molecular weight (Mn) 1000

(3) Acrylic polymer (C)
C1-1: Paraloid BPM-515, core-shell type graft copolymer (core component: acrylic rubber, shell component: methyl (meth) acrylate polymer), manufactured by Rohm and Haas Co.
C1-2: Mitsubishi Rayon Metabrene W-600A, core-shell type graft copolymer (core component: acrylic rubber, shell component: methyl methacrylate copolymer)
C2-1: Mitsubishi Rayon Metabrene P-531A, weight average molecular weight 4.5 million C2-2: Mitsubishi Rayon Metabrene P-530A, weight average molecular weight 3.1 million

(4) Glycerin fatty acid ester (D)
D-1: manufactured by Riken Vitamins Co., Ltd. Rikemar S-74, diglycerin full stearic acid ester D-2: manufactured by Solar Chemical Co., Ltd. Thilavazole VR-017, polyglycerin fatty acid ester number average molecular weight (Mn) = 1300

(5) Polyalkylene ethers other than polytetramethylene ether glycol (E)
E-1: polyethylene glycol, manufactured by Sanyo Chemical Industries, Ltd. PEG-20000, number average molecular weight (Mn) = 20000

Example 1
[Polylactic acid-based resin composition]
100 parts by mass of a polylactic acid resin (A-1) is supplied from a hopper, 1 part by mass of a polytetramethylene ether glycol (B-1) is melted and added by liquid injection, and a twin screw extruder (PCM-made by Ikegai Co., Ltd.) 30 ", screw diameter: 29 mm, L / D (ratio of length L to diameter D of extruder cylinder): 30, nozzle diameter: 4 mm, after melt kneading with a number of holes: 3, temperature: 220 ° C. The mixture was extruded, processed into pellets, and dried to obtain a polylactic acid-based resin composition.
[Sheet]
The polylactic acid-based resin composition obtained as described above is melt extruded at a T die temperature of 230 ° C. by a single screw extruder with a bore of 90 mm, brought into close contact with a cast roll temperature controlled to 20 ° C., and cooled. A 400 μm thick sheet (unstretched sheet) molded with the polylactic acid-based resin composition of the invention was obtained.

Examples 2 to 18 , Comparative Examples 1 to 13, Reference Examples 1 to 2
As shown in Table 1, the types and contents of polytetramethylene ether glycol (B), acrylic polymer (C), glycerin fatty acid ester (D) and polyalkylene ether (E) other than polytetramethylene ether glycol are changed as shown in Table 1 A polylactic acid-based resin composition was obtained in the same manner as in Example 1 except for the above.
Then, a sheet (unstretched sheet) having a thickness of 400 μm was obtained in the same manner as in Example 1 using the obtained polylactic acid-based resin composition.

Example 19
80 parts by mass of polylactic acid (A-1) and 12 parts by mass of acrylic polymer (C2-2) are dry-blended and supplied from a hopper to melt 8 parts by mass of polytetramethylene ether glycol (B-1) Add with a screw, twin screw extruder (Ikegai "PCM-30", screw diameter: 2
9 mm, L / D (ratio of length L to diameter D of extruder cylinder): 30, nozzle diameter: 4 m
After melt-kneading at m, number of holes: 3, temperature: 220 ° C.), the mixture was extruded, processed into pellets, and dried to obtain a master batch pellet (M-1).
The masterbatch pellets (M-1) and polylactic acid (A-1) obtained above were dry blended at a mass ratio [(M-1) / (A-1)] 10/90 to obtain Table 1 The resin composition shown in was produced. That is, the composition of this resin composition is such that the content of polylactic acid (A-1) is 98 parts by mass, the content of polytetramethylene ether glycol (B-1) is 0.8 parts by mass, an acrylic polymer ( The content of C2-2) was 1.2 parts by mass.

The compositions, melt viscosities, and sheet characteristic values of the polylactic acid-based resin compositions obtained in Examples 1 to 19 and Comparative Examples 1 to 13 are shown in Table 1.

As is clear from Table 1, the polylactic acid-based resin composition obtained in Examples 1 to 19 satisfied the composition defined in the present invention, so the obtained sheet has transparency and impact resistance. Was excellent.
On the other hand, in the polylactic acid-based resin composition obtained in Comparative Example 1, since the number average molecular weight of polytetramethylene ether glycol (B) is outside the range of the present invention, the obtained sheet is inferior in impact resistance. Met. Since the polylactic acid-based resin composition obtained in Comparative Examples 2 to 4 contained too little content of polytetramethylene ether glycol (B), the obtained sheet was inferior in impact resistance. In the polylactic acid-based resin composition obtained in Comparative Example 5, the content of the polytetramethylene ether glycol (B) was too large, so the obtained sheet was inferior in transparency. Moreover, since the polylactic acid-based resin composition obtained in Comparative Examples 6 to 12 did not contain polytetramethylene ether glycol (B), the obtained sheet was inferior in impact resistance.

Claims (5)

A resin composition comprising a polylactic acid resin (A) and a polytetramethylene ether glycol (B) having a number average molecular weight of 1200 or more, wherein polytetramethylene is used per 100 parts by mass of the polylactic acid resin (A) The polylactic acid-type resin composition characterized by containing 0.5-4.0 mass parts of ether glycol (B). Furthermore, the acrylic polymer (C) is used in an amount of 0.1 to 100 parts by mass of the polylactic acid resin (A)
The polylactic acid-based resin composition according to claim 1, which contains 3 parts by mass. Furthermore, 0.1 to 3 parts by mass of at least one selected from polyalkylene ether (E) other than glycerin fatty acid ester (D) and polytetramethylene ether glycol is contained with respect to 100 parts by mass of polylactic acid resin (A) The polylactic acid-based resin composition according to claim 1 or 2, wherein The sheet-like molded object which consists of a polylactic acid-type resin composition in any one of Claims 1-3. A resin composition comprising a polylactic acid resin (A) and a polytetramethylene ether glycol (B) having a number average molecular weight of 1200 or more, wherein polytetramethylene is used per 100 parts by mass of the polylactic acid resin (A) A masterbatch pellet for a polylactic acid-based resin composition comprising 2 to 30 parts by mass of an ether glycol (B).