JP5907698B2 - Aliphatic polyester resin sheet and plastic case for packaging container using the same - Google Patents

Description

  The present invention relates to an aliphatic polyester-based resin sheet and a plastic case for a packaging container using the aliphatic polyester-based resin sheet.

  Among aliphatic polyester resins, for example, lactic acid polymers are derived from plants and their biodegradation characteristics are attracting attention, and are expected to be used for disposable films, sheets, bags, cases, etc. for packaging applications. It has been. On the other hand, lactic acid-based polymers have problems such as insufficient impact resistance and heat resistance, and there are cases where development in the packaging application field is restricted.

  Japanese Patent Application Laid-Open No. 2008-69299 discloses a polylactic acid composition for forming a film, sheet, or bag having improved impact resistance of a lactic acid-based polymer (see Patent Document 1). In some cases, it was insufficient in terms of sex. Japanese Patent Application Laid-Open No. 2011-89084 discloses a polylactic acid-based resin composition that improves the impact resistance of a lactic acid-based polymer while maintaining high transparency and a molded product thereof (patents). In some cases, the lack of heat resistance may be a problem, and this is the same as the polylactic acid composition.

  Japanese Patent Application Laid-Open No. 2011-168716 discloses a polylactic acid resin composition with improved impact resistance and heat resistance (see Patent Document 3), but when high heat resistance is required. If it is still insufficient, that is, if it is used for applications such as plastic cases that require high heat resistance, deformation troubles may occur during storage.

JP 2008-69299 A JP 2011-89084 A JP2011-168716A

  As described above, various polylactic acid resin compositions and molded articles thereof have been proposed so far, but polylactic acid resin compositions having high heat resistance while ensuring impact resistance are still realized. However, such a polylactic acid resin composition has been eagerly desired.

  Accordingly, an object of the present invention is to provide an aliphatic polyester resin composition that improves the impact resistance of aliphatic polyester resins including lactic acid polymers and has excellent heat resistance. Moreover, it aims at providing the aliphatic polyester-type resin sheet which is formed using this aliphatic polyester-type resin composition and has impact resistance and the outstanding heat resistance. In particular, an object of the present invention is to provide an aliphatic polyester-based resin sheet suitable for a plastic case used as a packaging container for storing haberdashery such as cosmetics and daily necessities for sale and display.

  The inventors of the present invention have improved impact resistance and improved heat resistance by stretching a resin composition containing an aliphatic polyester-based resin and a polyglycerin fatty acid ester in a specific ratio and then stretching the resin composition. The inventors have found that a sheet having high transparency can be obtained, and have completed the present invention.

  That is, the aliphatic polyester resin sheet of the present invention contains an aliphatic polyester resin and a polyglycerol fatty acid ester, and the content of the polyglycerol fatty acid ester is the fatty acid polyester resin and the polyglycerol fatty acid ester. The resin composition is 0.2% by mass or more and less than 3.0% by mass with respect to a total amount of 100% by mass, and is formed by at least 1.1 times stretching in at least one uniaxial direction. And

  Here, the weight average molecular weight of the polyglycerol fatty acid ester is preferably 1,000 or more and less than 3,000.

  In the present invention, after the resin composition is melt-formed, it is preferably stretched at least in a uniaxial direction so that the area magnification is 2 times or more.

  Moreover, content of the said polyglycerol fatty acid ester shall be 0.5 mass% or more and 2.0 mass% or less with respect to 100 mass% of total amounts of the said aliphatic polyester-type resin and the said polyglycerol fatty acid ester. Is preferably 0.5% by mass or more and 1.2% by mass or less.

  In the present invention, the aliphatic polyester resin is preferably a lactic acid polymer.

  Here, the lactic acid polymer has a constitutional ratio of D-lactic acid and L-lactic acid of D-lactic acid: L-lactic acid = 99.5: 0.5 to 95: 5, or D-lactic acid: L. -It is preferable that it is lactic acid = 0.5: 99.5-5: 95.

  The plastic case for a packaging container of the present invention is characterized by using any of the above aliphatic polyester resin sheets.

  Since the aliphatic polyester resin sheet of the present invention has excellent heat resistance and impact resistance, it can be used in a wide range of applications such as various packaging materials such as films, sheets, bags, and cases, and agricultural materials. Can do. Furthermore, since high transparency is maintained by adjusting the quantity of the polyglycerol fatty acid ester mix | blended with aliphatic polyester-type resin, it can use suitably for the plastic case for packaging containers.

  The present invention will be described in detail below, but the present invention is not limited to these embodiments.

  The aliphatic polyester resin sheet of the present invention (hereinafter sometimes referred to as “the present sheet”) contains an aliphatic polyester resin and a polyglycerol fatty acid ester. However, the aliphatic polyester-based resin is contained as a main component, and the content of the polyglycerol fatty acid ester is 0.2% with respect to 100% by mass of the total amount of the fatty acid polyester-based resin and the polyglycerol fatty acid ester. It is necessary to be at least mass% and less than 3.0 mass%.

(Aliphatic polyester resin)
As the aliphatic polyester resin constituting the main component of the resin composition forming the sheet, a chemically synthesized resin, a resin synthesized by fermentation using a microorganism, and a mixture thereof can be used.

  Chemically synthesized aliphatic polyester resins include poly-ε-caprolactam obtained by ring-opening polymerization of lactone, polyethylene adipate obtained by polymerizing dibasic acid and diol, polyethylene azelate, polytetramethylene succinate. Nate, cyclohexanedicarboxylic acid / cyclohexanedimethanol condensate, etc., lactic acid polymers obtained by polymerizing hydroxycarboxylic acid, polyglycol, etc., part of the ester bond of the above aliphatic polyester, for example, 50% or less is amide Examples thereof include aliphatic polyesters substituted with bonds, ether bonds, urethane bonds, and the like.

  Examples of the aliphatic polyester resin fermented and synthesized by microorganisms include polyhydroxybutyrate, a copolymer of hydroxybutyrate and hydroxyvalerate, and the like.

  In the present invention, the lactic acid polymer refers to a homopolymer of D-lactic acid or L-lactic acid or a copolymer thereof, and specifically, poly (D-lactic acid) whose structural unit is D-lactic acid. And poly (L-lactic acid) whose structural unit is L-lactic acid, and poly (DL-lactic acid) which is a copolymer of L-lactic acid and D-lactic acid, and a mixture thereof.

  The lactic acid polymer can be produced by a known method such as a condensation polymerization method or a ring-opening polymerization method. For example, in the condensation polymerization method, D-lactic acid, L-lactic acid, or a mixture thereof can be directly subjected to dehydration condensation polymerization to obtain a lactic acid polymer having an arbitrary composition. Further, in the ring-opening polymerization method, lactide, which is a cyclic dimer of lactic acid, is subjected to ring-opening polymerization in the presence of a predetermined catalyst while using a polymerization regulator or the like as necessary, and lactic acid having an arbitrary composition. A polymer can be obtained. The lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, and DL-lactide, which is a dimer of D-lactic acid and L-lactic acid, By mixing and polymerizing these as necessary, a lactic acid polymer having an arbitrary composition and crystallinity can be obtained.

  In the lactic acid polymer used in the present invention, the constituent ratio of D-lactic acid and L-lactic acid is D-lactic acid: L-lactic acid = 100: 0 to 85:15, or D-lactic acid: L- Lactic acid is preferably 0: 100 to 15:85, more preferably D-lactic acid: L-lactic acid = 99.5: 0.5 to 95: 5, or D-lactic acid: L-lactic acid = 0. .5: 99.5-5: 95. A lactic acid polymer having a composition ratio of D-lactic acid and L-lactic acid of 100: 0 or 0: 100 exhibits very high crystallinity, has a high melting point, and tends to be excellent in heat resistance and mechanical properties. That is, when the film is stretched or heat-treated, the resin is crystallized to improve heat resistance and mechanical properties, which is preferable. On the other hand, a lactic acid-based polymer composed of D-lactic acid and L-lactic acid is preferable because flexibility is imparted and film forming stability and stretching stability are improved. Therefore, in consideration of the balance between the heat resistance of the sheet obtained, molding stability and stretching stability, the lactic acid polymer used in the present invention has a composition ratio of D-lactic acid and L-lactic acid of D- Lactic acid: L-lactic acid = 99.5: 0.5 to 95: 5 or D-lactic acid: L-lactic acid = 0.5: 99.5 to 5:95 is more preferable.

  In the present invention, lactic acid polymers having different copolymerization ratios of D-lactic acid and L-lactic acid may be blended. In this case, what is necessary is just to make it the value which averaged the copolymerization ratio of D-lactic acid and L-lactic acid of a some lactic acid-type polymer in the said range. By blending a homopolymer of D-lactic acid and L-lactic acid and a copolymer, it is possible to balance the difficulty of bleeding and the expression of heat resistance.

  The lactic acid polymer used in the present invention preferably has a high molecular weight. For example, the weight average molecular weight is preferably 50,000 or more, more preferably 60,000 or more and 400,000 or less, and more preferably 100,000 or more. , 300,000 or less is particularly preferable. If the weight average molecular weight of the lactic acid polymer is less than 50,000, the mechanical properties of the obtained sheet may be inferior.

(Polyglycerin fatty acid ester)
Examples of the polyglycerin fatty acid ester used in the present invention include esters obtained by reacting polyglycerin and fatty acids.

  Examples of the polyglycerin that is a constituent of the polyglycerin fatty acid ester include diglycerin, triglycerin, tetraglycerin, pentaglycerin, hexaglycerin, heptaglycerin, octaglycerin, nonaglycerin, decaglycerin, and the like. Then, diglycerin and decaglycerin are preferably used. Moreover, in this invention, what was enumerated here can be used as a 1 type, or 2 or more types as a mixture.

  As the fatty acid that is the other component of the polyglycerol fatty acid ester, a fatty acid having 12 or more carbon atoms is used. Specifically, for example, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid linolenic acid, nonadecanoic acid, arachidic acid, gadleyic acid, eicosadienoic acid, arachidonic acid, behenic acid, Erucic acid, docosadienoic acid, lignoceric acid, isostearic acid, ricinoleic acid, 12-hydroxystearic acid, 9-hydroxystearic acid, 10-hydroxystearic acid, hydrogenated castor oil fatty acid (12-hydroxystearic acid plus a small amount of stearin Acid and fatty acid containing palmitic acid). Of these, palmitic acid, stearic acid, and oleic acid are preferred. In this invention, what was enumerated here can be used 1 type or in mixture of 2 or more types.

  The production method of the polyglycerin fatty acid ester is not particularly limited, but the polyglycerin fatty acid ester is, for example, using the polyglycerin and the fatty acid in the presence of a catalyst such as phosphoric acid, p-toluenesulfonic acid, and caustic soda. Alternatively, it is obtained by removing the produced water out of the system by heating at a temperature of 100 ° C. to 300 ° C., preferably 120 ° C. to 260 ° C. without catalyst. The reaction is preferably performed in the presence of an inert gas. Moreover, you may carry out in azeotropic solvents, such as toluene or xylene. Specific examples of the polyglycerol fatty acid ester synthesized in this manner include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, deca A glycerol oleate etc. are mentioned, These 1 type, or 2 or more types of mixtures are used. Of these, diglycerin stearic acid ester and decaglycerin oleic acid ester are particularly preferably used.

  The weight average molecular weight of the polyglycerol fatty acid ester used in the present invention is preferably 1,000 or more and 3,000 or less, more preferably 1,000 or more and 2,000 or less, and 1,000 or more. 1,500 or less is particularly preferable.

  If the weight average molecular weight of the polyglycerin fatty acid ester is 1,000 or more, the impact resistance of the resulting sheet becomes good, which is preferable. Moreover, if the weight average molecular weight of polyglycerol fatty acid ester is 3,000 or less, it is easy to disperse | distribute to an aliphatic polyester-type resin, and since a homogeneous sheet | seat is obtained, it is preferable.

  The content ratio of the polyglycerol fatty acid ester in the resin composition forming the sheet is 0.2% by mass or more and less than 3.0% by mass with respect to 100% by mass of the total amount of the aliphatic polyester resin and the polyglycerol fatty acid ester. The lower limit is preferably 0.5% by mass or more, and the upper limit is preferably 2.0% by mass or less, and is preferably 1.5% by mass or less. More preferably, the content is 1.2% by mass or less.

  If the content ratio of the polyglycerin fatty acid ester in the resin composition forming the sheet is 0.2% by mass or more, a sheet having a practical level of impact resistance is obtained, and if it is 0.5% by mass or more. The impact resistance of this sheet is sufficient, which is preferable. On the other hand, when the content ratio of the polyglycerin fatty acid ester is less than 3.0% by mass, when the resin composition is melt-formed with an extruder or the like, the extrusion discharge amount is stable, and is 2.0% by mass or less. It is preferable because the extrusion discharge amount is more stable. In particular, if the content of the polyglycerin fatty acid ester is 1.2% by mass or less, it is preferable because the high transparency of the aliphatic polyester resin is maintained.

  Moreover, when using this sheet | seat for the packaging container for long-term storage, it is preferable to add a hydrolysis inhibiting agent in order to provide durability with respect to high temperature and high humidity.

Examples of the hydrolysis inhibitor used in the present invention include carbodiimide compounds. Preferred examples of the carbodiimide compound include those having a basic structure represented by the following general formula.

-(N = C = N-R-) _n-

  In the formula, n represents an integer of 1 or more, and R represents an organic bond unit. For example, R can be either aliphatic, alicyclic, or aromatic. In addition, n is generally an appropriate integer selected from 1 to 50.

  Specifically, for example, bis (dipropylphenyl) carbodiimide, poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (tolylcarbodiimide), poly ( Examples of the carbodiimide compound include diisopropylphenylenecarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide), poly (triisopropylphenylenecarbodiimide), and the like. These carbodiimide compounds may be used alone or in combination of two or more.

  In this invention, it is preferable to add 0.1-3.0 mass parts of carbodiimide compounds with respect to 100 mass parts of aliphatic polyester-type resin which comprises this sheet | seat. If the addition amount of the carbodiimide compound is 0.1 parts by mass or more, the durability of the resulting sheet is sufficient, which is preferable. Moreover, if the addition amount of a carbodiimide compound is 3.0 mass parts or less, since the coloring of the sheet obtained is few and transparency is maintained, it is preferable.

(Other ingredients)
The resin composition forming the sheet may contain other resins and the like other than those described above as long as the effects of the present invention are not impaired. Moreover, you may contain antioxidant, a light stabilizer, a heat stabilizer, a dispersing agent, a ultraviolet absorber, a compatibilizer, a lubricant, an organic filler, an inorganic filler, and other additives.

(Aliphatic polyester resin sheet)
It is important that this sheet is formed by melt-forming a resin composition obtained by blending a specific amount of a polyglycerin fatty acid ester with an aliphatic polyester resin, and then stretching at least 1.1 times in a uniaxial direction. It is. That is, this sheet is a stretched sheet, and the extent of stretching is preferably stretched to 2 times or more in terms of area magnification, more preferably stretched to 4 times or more, and the upper limit of the area magnification is It is preferably 10 times or less. In addition, the stretching is preferably performed in a biaxial direction, and the biaxial stretching makes it easy to obtain a homogeneous sheet having small physical property anisotropy. By stretching the area magnification to 2 times or more, the effect of improving the heat resistance and mechanical strength of the obtained sheet is sufficiently obtained, which is preferable.
This sheet is formed by stretching as described above, so that its heat resistance and mechanical strength are improved, and it has both high heat resistance and good impact resistance that could not be realized in the past. A clear sheet is obtained.

  The aliphatic polyester-based resin sheet of the present invention may be a single-layered sheet formed using a resin composition obtained by blending an aliphatic polyester-based resin with a polyglycerol fatty acid ester at a specific ratio, Or it is good also as a sheet | seat of the multilayer structure which laminated | stacked two or more layers formed using this resin composition.

  In the case of a multi-layered sheet, the resin composition forming each layer may be the same or different, and other layers may be laminated. For example, a resin layer A formed from a resin composition A obtained by blending an aliphatic polyester resin with a polyglycerol fatty acid ester in a specific ratio, and a polyglycerol fatty acid ester blended with an aliphatic polyester resin at a specific ratio. And a resin layer B formed from the resin composition B. The resin layer A / resin layer B, resin layer A / resin layer B / resin layer A, resin It can be considered that layers B / resin layer A / resin layer B are laminated in this order. In addition to the resin layer A and the resin layer B, other layers may be provided, and other layers such as an adhesive layer may be interposed between the resin layers A and B.

(Method for producing aliphatic polyester resin sheet)
The method for producing the aliphatic polyester resin sheet of the present invention is not particularly limited, and a known method can be adopted.
Below, although an example is given and demonstrated about the manufacturing method of the aliphatic polyester-type resin sheet of this invention, it is not limited to the following manufacturing method at all.

  First, a specific proportion of a polyglycerin fatty acid ester is blended with an aliphatic polyester-based resin, and other additives are blended as necessary to prepare a resin composition. Specifically, polyglycerin fatty acid ester is added to the aliphatic polyester-based resin, and further, an anti-hydrolysis agent or the like is added as necessary, and the mixture is mixed with a ribbon blender, tumbler, Henschel mixer, etc. Alternatively, the resin composition can be obtained by kneading using a twin screw extruder or the like at a temperature equal to or higher than the melting point of the resin (for example, 170 ° C. to 230 ° C. in the case of a lactic acid polymer). Alternatively, the resin composition can be obtained by adding a predetermined amount of an aliphatic polyester-based resin, a polyglycerin fatty acid ester, and, if necessary, a hydrolysis inhibitor or the like with a separate feeder or the like. Alternatively, a so-called master batch in which a polyglycerol fatty acid ester and, if necessary, a hydrolysis inhibitor and the like are blended with an aliphatic polyester resin in a high concentration is prepared in advance, and this master batch and the aliphatic polyester resin are prepared. It can also be mixed to obtain a resin composition having a desired concentration.

  Next, the resin composition thus obtained is melted and formed into a sheet shape. For example, after drying the resin composition, it may be supplied to an extruder and heated to a temperature equal to or higher than the melting point of the resin to be melted, or the resin composition may be supplied to the extruder without drying. When not drying, it is preferable to use a vacuum vent during melt extrusion. The conditions such as the extrusion temperature need to be set considering that the molecular weight decreases due to decomposition. For example, the extrusion temperature is in the range of 170 ° C. to 230 ° C. in the case of a lactic acid polymer. Is preferred. Thereafter, the melted resin composition is extruded from the slit-shaped discharge port of the T die, and is solidified on a cooling roll to form a cast sheet.

  The aliphatic polyester-based resin sheet of the present invention needs to be obtained by melt-forming a resin composition and then stretching it 1.1 times or more in at least one uniaxial direction. By stretching the cast sheet thus obtained, its heat resistance and mechanical strength can be improved.

  The stretching temperature for stretching the cast sheet is preferably a temperature in the range of + 50 ° C. (Tg + 50 ° C.) from the glass transition temperature (Tg) of the resin. For example, in the case of a lactic acid polymer, 50 ° C. or higher. It is preferable that it is 90 degrees C or less. When the stretching temperature is within this range, the sheet is not broken during stretching, the stretching orientation is increased, and the effect of improving heat resistance and mechanical strength is easily obtained, which is preferable.

  The aliphatic polyester resin sheet of the present invention is preferably stretched in the biaxial direction. By biaxial stretching, a homogeneous sheet having small physical property anisotropy is easily obtained. In the present invention, the stretching order of biaxial stretching is not particularly limited, and for example, simultaneous biaxial stretching or sequential stretching may be used. After melt film formation, the film may be stretched to MD by roll stretching using a stretching facility, then stretched to TD by tenter stretching, or biaxially stretched by tubular stretching or the like.

  In the present invention, in order to impart heat resistance or dimensional stability to the aliphatic polyester resin sheet, it is preferable to perform heat setting after stretching. The treatment temperature for heat fixing to the sheet is preferably 90 to 160 ° C, and more preferably 110 to 140 ° C. The processing time required for heat setting is preferably 1 second to 5 minutes. There are no particular limitations on the stretching equipment and the like at that time, but it is preferable to employ tenter stretching that can be heat-set after stretching.

(Thickness of this sheet)
The thickness of the aliphatic polyester resin sheet of the present invention is not particularly limited, but is usually 20 μm to 500 μm, and is preferably in the range of about 50 μm to 300 μm in view of practical handling. . If the sheet thickness is within this range, it can be used for a wide range of applications such as various packaging materials such as films, sheets, bags, cases, and agricultural materials.

(Plastic case for packaging container)
The aliphatic polyester resin sheet of the present invention can be formed in a plastic case having a shape such as a housing. For example, if a plastic case is formed by attaching a bent line or the like to a corner portion of a housing or the like, an excellent plastic case for a packaging container that has a flat surface and can realize good transparency can be obtained. .

<Explanation of terms>
In general, "film" refers to a thin flat product that is extremely small compared to its length and width and whose maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll (Japan) Industrial standard JISK6900), and in general, “sheet” refers to a product that is thin by definition in JIS and generally has a thickness that is small instead of length and width. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

  In addition, the expression “main component” in the present specification includes the meaning of allowing other components to be contained within a range that does not hinder the function of the main component unless otherwise specified. At this time, although the content ratio of the main component is not specified, the main component (when two or more components are main components, the total amount thereof) is 50% by mass or more, preferably 70% in the composition. It occupies at least 90% by mass, particularly preferably at least 90% by mass (including 100%).

In the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” and “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It means “smaller”.
Further, in the present invention, when expressed as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and “Y or less” (Y is an arbitrary number). ) Includes the meaning of “preferably smaller than Y” unless otherwise specified.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical idea of the present invention.

<Measurement and evaluation method>
Below, the measuring method and evaluation method of various physical-property values of the sheet | seat obtained by the Example and the comparative example are demonstrated. Hereinafter, the sheet take-up (flow) direction is indicated by MD, and the orthogonal direction thereof is indicated by TD.

(Impact resistance)
About the obtained sheet | seat, the following impact measuring apparatus was used and the maximum impact force point energy (kgf * mm) was measured based on the following measurement conditions. The obtained maximum impact power point energy (kgf · mm) was substituted into the following formula to determine the impact resistance improvement rate, and the impact resistance was evaluated based on the following evaluation criteria. Note that the symbols “◯” and “Δ” are above the practical level.

Measuring device: High-speed impact tester HTM-1 type (manufactured by Shimadzu Corporation)
Test temperature: 23 ° C
Test speed: 3 m / second Stroke core diameter: 0.5 inch
Support base: 50mm

Impact resistance improvement rate = (maximum impact power point energy of each sheet / maximum impact power point energy of the sheet of Comparative Example 1)

Evaluation criteria:
○ When impact resistance improvement rate ≧ 5 △ 5> When impact resistance improvement rate ≧ 4 × When impact resistance improvement rate <4

(Heat-resistant)
A 100 mm × 100 mm square sample was taken from the obtained sheet to obtain a heat resistant test piece. Measure the length (mm) of the four sides of the heat-resistant test piece, and then measure the length (mm) of the four sides after immersing the heat-resistant test piece in a constant temperature water bath adjusted to 55 ° C. for 10 minutes. did. The total of the lengths of the four sides before being immersed in the thermostatic bath (side length before Σ immersion) and the total of the lengths of the four sides after immersion (side length after Σ immersion) are expressed as follows: The dimensional change (mm) was determined by substitution, and the heat resistance was evaluated based on the following evaluation criteria. However, the symbols “◯” and “Δ” are above the practical level.

Dimensional change = | (side length before Σ immersion) / 4− (side length after Σ immersion) / 4) | (mm)

Evaluation criteria:
○ When dimensional change ≤ 1 △ 1 <When dimensional change ≤ 2 × When dimensional change> 2

(transparency)
About the obtained sheet | seat, the following measuring apparatus was used and haze (haze value) (%) was measured based on the following measurement specification. The obtained haze (%) was substituted into the following equation to determine the amount of haze change (%), and the transparency was evaluated based on the following evaluation criteria.

Haze change amount = (haze of each sheet) − (haze of sheet of comparative example 2) (%)

Evaluation criteria:
○ When haze change ≦ 0.3 △ 0.3 <When haze change ≦ 1.0 × When haze change> 1.0

Haze (%) measurement:
Measuring device: Turbidimeter NDH5000 type (manufactured by Nippon Denshoku Industries Co., Ltd.)
Measurement standards: JIS K7361-1 and JIS K7136

[Example 1]
(Preparation of resin composition)
Pellets of lactic acid polymer A having a weight average molecular weight of 200,000 (NW4043D: Nature Works, D-form content: 4%), and polyglycerin fatty acid ester (tylabazole VR-17: Taiyo Kagaku, weight average molecular weight 1, 400) were mixed at a ratio of 90% by weight / 10% by weight to form a mixture. This mixture was melt-kneaded using a twin screw extruder and then pelletized to produce a so-called master batch. The master batch and a lactic acid polymer B having a weight average molecular weight of 200,000 (NW4032D: manufactured by Nature Works, D-form content: 1.5%) are mixed at a ratio of 5% by mass / 95% by mass to obtain a resin composition. Was made.

(Production of aliphatic polyester resin sheet)
The obtained resin composition was supplied to an extruder heated to 200 ° C. From the extruder, the molten resin composition was extruded into a sheet using a T-die and cooled and solidified to form a sheet. The obtained sheet was biaxially stretched 2.5 times in MD and 2.8 times in TD at a temperature of 75 ° C., and then heat-treated at 120 ° C. for 30 seconds to obtain an aliphatic polyester resin sheet having a thickness of 50 μm. Obtained. The resulting aliphatic polyester resin sheet was evaluated for impact resistance, heat resistance, and transparency. The results are shown in Table 1.

[Example 2]
In the production of the resin composition of Example 1, the aliphatic polyester series was the same as Example 1 except that the master batch and the lactic acid polymer B were mixed at a ratio of 10% by mass / 90% by mass. A resin sheet was obtained. About the obtained aliphatic polyester-type resin sheet, evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Example 3]
In the production of the resin composition of Example 1, the aliphatic polyester series was the same as Example 1 except that the master batch and the lactic acid polymer B were mixed at a ratio of 15% by mass / 85% by mass. A resin sheet was obtained. About the obtained aliphatic polyester-type resin sheet, evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Example 4]
In the production of the resin composition of Example 1, in the same manner as in Example 1 except that the master batch and the lactic acid polymer B were mixed at a ratio of 2.5% by mass / 97.5% by mass. An aliphatic polyester resin sheet was obtained. About the obtained aliphatic polyester-type resin sheet, evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Comparative Example 1]
(Preparation of resin composition)
Pellets of lactic acid polymer A having a weight average molecular weight of 200,000 (NW4043D: manufactured by Nature Works / D content 4%), and polyglycerol fatty acid ester (tylabazole VR-17: manufactured by Taiyo Kagaku Co., Ltd., weight average molecular weight 1, 400) were mixed at a ratio of 90% by weight / 10% by weight to form a mixture. This mixture was melt-kneaded using a twin screw extruder and then pelletized to produce a so-called master batch. The master batch and a lactic acid polymer B having a weight average molecular weight of 200,000 (NW4032D: manufactured by Nature Works, D-form content: 1.5%) are mixed at a ratio of 15% by mass / 85% by mass to obtain a resin composition. Was made.

(Production of sheet)
The obtained resin composition was supplied to an extruder heated to 200 ° C. From the extruder, the molten resin composition was extruded into a sheet using a T-die and cooled and solidified to form a sheet, and a sheet (unstretched) having a thickness of 50 μm was obtained as it was. About the obtained sheet | seat, evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Comparative Example 2]
In preparation of the resin composition of Example 1, pellets of lactic acid-based polymer B having a weight average molecular weight of 200,000 (NW4032D: manufactured by Nature Works, D-body content 1.5%) were used as they were as the resin composition. A sheet was produced in the same manner as in Example 1 except for the above. About the obtained sheet | seat, evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Comparative Example 3]
In the production of the resin composition of Example 1, a sheet was produced in the same manner as in Example 1 except that the master batch and the lactic acid polymer B were mixed at a ratio of 30% by mass / 70% by mass. Although an attempt was made, the discharge amount from the extruder was not stable, and a sheet having a good appearance could not be obtained. Therefore, this sheet could not be evaluated in the same manner as in Example 1.

  As is clear from Table 1, the aliphatic polyester resin sheets of Examples 1 to 4 have an impact resistance improvement rate of 4 or more, and have an impact resistance of a practical level or more. It was found that the sheets 1 to 3 had a very excellent impact resistance with an impact resistance improvement rate of 6 or more. On the other hand, it was found that the sheets of Comparative Examples 1 and 2 had a low impact resistance improvement rate and were inferior in impact resistance.

  In addition, the aliphatic polyester resin sheets of Examples 1 to 4 have a dimensional change of 2 mm or less and satisfy heat resistance of a practical level or more, whereas the sheet of Comparative Example 1 is significantly wavy and deformed. It was found that the heat resistance was inferior and could not be put to practical use. Furthermore, it turned out that the aliphatic polyester-type resin sheet of Examples 1-4 has a haze change amount of 1.0% or less, and has favorable transparency.

  As mentioned above, it turned out that the aliphatic polyester-type resin sheet of Examples 1-4 is a sheet | seat provided with all the characteristics of favorable impact resistance, high heat resistance, and favorable transparency.

  The aliphatic polyester resin sheet of the present invention can be used for applications such as plastic cases that require a high degree of heat resistance. For example, a transparent plastic case that stores and sells haberdashery such as cosmetics and daily necessities It was also found that a flat case with a flat and transparent appearance can be obtained.

Claims (7)

An aliphatic polyester-based resin and a polyglycerol fatty acid ester are contained, and the content of the polyglycerol fatty acid ester is 0.2% by mass with respect to 100% by mass of the total amount of the aliphatic polyester-based resin and the polyglycerol fatty acid ester. As mentioned above, after melt-forming a resin composition having a weight average molecular weight of less than 3.0 mass% and a polyglycerin fatty acid ester of 1,000 or more and 2,000 or less , at least uniaxially 1.1. An aliphatic polyester resin sheet characterized by being stretched at least twice. 2. The aliphatic polyester resin sheet according to claim 1, wherein the aliphatic polyester resin sheet is formed by at least uniaxial stretching so that the area ratio is 2 times or more after melt-forming the resin composition. Content of the said polyglycerol fatty acid ester is 0.5 mass% or more and 2.0 mass% or less with respect to 100 mass% of total amounts of the said aliphatic polyester-type resin and the said polyglycerol fatty acid ester. The aliphatic polyester resin sheet according to claim 1 or 2 . Content of the said polyglycerol fatty acid ester is 0.5 mass% or more and 1.2 mass% or less with respect to 100 mass% of total amounts of the said aliphatic polyester-type resin and the said polyglycerol fatty acid ester. The aliphatic polyester resin sheet according to any one of claims 1 to 3 . The aliphatic polyester resin sheet according to any one of claims 1 to 4 , wherein the aliphatic polyester resin is a lactic acid polymer. The composition ratio of D-lactic acid to L-lactic acid in the lactic acid-based polymer is D-lactic acid: L-lactic acid = 99.5: 0.5 to 95: 5, or D-lactic acid: L-lactic acid = 0. 5: 99.5-5: 95, The aliphatic polyester resin sheet according to claim 5 . A plastic case for a packaging container, comprising the aliphatic polyester resin sheet according to any one of claims 1 to 6 .