JP6430803B2 - Thermoforming sheet - Google Patents

Description

  The present invention relates to a thermoforming sheet. More specifically, the present invention relates to a sheet made of a polylactic acid resin composition that can be suitably used for molded articles such as packs and trays of daily necessities, cosmetics, home appliances, etc., and a method for producing a molded article formed by molding the sheet.

  Polylactic acid resin is inexpensive because L-lactic acid as a raw material is produced by fermentation using sugar extracted from corn, straw, etc., and the carbon dioxide emission is extremely low because the raw material is derived from plants. In addition, due to the characteristics of the resin such as high rigidity and high transparency, its use is currently expected.

  For example, in Patent Document 1, a sheet having a specific retardation composed of a polylactic acid resin composition containing a polylactic acid-based resin, a plasticizer, and a crystal nucleating agent is thermoformed to provide excellent transparency, heat resistance, It has been reported that a molded article having excellent strength can be obtained with good thermoformability.

  In addition, Patent Document 2 discloses (A) 100 parts by weight of a lactic acid-based polymer and (B) an organic crystal nucleating agent containing a mixture of two or more aliphatic carboxylic acid amides having two or more amide bonds. By thermoforming a sheet comprising a composition containing 3 parts by weight and (C) 0.1 to 7 parts by weight of a crystallization accelerator, a molded article having transparency and heat resistance can be produced with excellent production efficiency. It has been reported that it can be obtained.

JP 2014-51646 A International Publication No. 2006/121056

  However, the conventional polylactic acid resin needs further improvement as a resin that can replace various plastics. That is, in the thermoforming of polylactic acid resin, transparency is maintained, the temperature range capable of thermoforming is wide, the crystallization speed is sufficient, that is, sufficient thermoformability (temperature at which both formability and crystallization are compatible) A polylactic acid resin sheet for thermoforming that can realize a wide range) is desired. More generally, the manufactured polylactic acid resin sheet for thermoforming is manufactured and sold as a raw roll (a cylindrical roll of resin sheet). However, depending on the storage conditions in the period until sales and molding, the subsequent thermoformability In particular, it has been a big problem that thermoformability deteriorates due to storage at a relatively high temperature (30 to 45 ° C.) such as storage in a warehouse in summer.

  The present invention relates to a thermoforming sheet comprising a polylactic acid resin composition having good thermoformability even after storage at such a relatively high temperature in summer, and a method for producing a molded body formed by molding the sheet. .

  As a result of intensive studies in view of such circumstances, the present inventors have used a specific amount of two types of aliphatic amides having different structures in a system in which a specific amount of a plasticizer and a dispersant is blended with a polylactic acid resin. As a result, it was found that a thermoforming sheet having excellent thermoformability even after storage at a high temperature was obtained, and the present invention was completed.

That is, the present invention relates to the following [1] to [2].
[1] The polylactic acid resin has 0.05 to 2 parts by mass of an aliphatic amide having a hydroxyl group and two or more amide bonds, and 100 to part by mass of the polylactic acid resin. First, the aliphatic amide having two or more amide bonds is contained in an amount of 0.05 to 2 parts by mass, and the total content of the plasticizer and the dispersant is 0.5 to 4.5 parts by mass. A thermoforming sheet comprising a polylactic acid resin composition comprising:
[2] A method for producing a thermoformed article comprising the following steps (1) and (2).
Step (1): Step (2) for heating the thermoforming sheet described in [1] above to a temperature range not lower than the glass transition temperature (Tg) and lower than the melting point (Tm) of the polylactic acid resin composition. Step of thermoforming the sheet obtained in (1) using a mold having a mold temperature of 60 ° C. or higher and 140 ° C. or lower.

  The thermoforming sheet of the present invention is excellent in thermoformability, in particular, thermoformability even after storage at high temperature, and therefore a molded article having a good appearance can be provided very easily. Moreover, since it is excellent in thermoformability even after high-temperature storage, the thermoforming sheet of the present invention has an excellent effect of excellent storage stability.

FIG. 1 is a view showing a molding die used in Examples. FIG. 2 is a graph showing the transition of sheet half crystallization time according to 45 ° C. storage time in Test Example 6.

  The thermoforming sheet of the present invention comprises a polylactic acid resin composition containing a specific amount of a plasticizer and a dispersant in total in a polylactic acid resin, and further containing a specific amount of two types of aliphatic amides having different structures. In particular, it has one feature.

[Polylactic acid resin composition]
[Polylactic acid resin]
Examples of the polylactic acid resin include commercially available polylactic acid resins such as Nature Works PLA / NW3001D and NW4032D manufactured by Nature Works, and Eco Plastic U'z S-09, S-12, and S- manufactured by Toyota Motor Corporation. In addition to 17 and the like, a polylactic acid resin synthesized from lactic acid or lactide can be used. From the viewpoint of thermoformability and transparency after storage at high temperature, a polylactic acid resin having an optical purity of 90% or more is preferable. For example, a polylactic acid resin (NW4032D manufactured by Nature Works) having a relatively high molecular weight and high optical purity. Etc.) is preferred.

  Further, in the present invention, as the polylactic acid resin, 2 obtained by using a lactic acid component mainly composed of different isomers from the viewpoint of thermoformability and transparency after storage of the polylactic acid resin composition at high temperature. You may use the stereocomplex polylactic acid resin which consists of a kind of polylactic acid.

  In addition, the polylactic acid resin in the present invention may contain a biodegradable polyester resin other than the polylactic acid resin or a non-biodegradable resin such as polypropylene as a polymer alloy by blending with the polylactic acid resin. In the present specification, “biodegradable” means a property that can be decomposed into a low molecular weight compound by a microorganism in nature. Specifically, JIS K6953 (ISO 14855) “controlled aerobic composting conditions”. This means biodegradability based on the “Aerobic and Ultimate Biodegradation and Disintegration Test”.

  From the viewpoint of biodegradability, the content of the polylactic acid resin is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and more preferably 95% by mass or more in the polylactic acid resin composition. Even more preferred.

[Plasticizer]
The plasticizer used by this invention is not specifically limited, The plasticizer used for general biodegradable resin is mentioned. Of these, compounds having two or more ester groups in the molecule are preferred from the viewpoints of thermoformability and transparency after storage at high temperatures. Examples of such compounds include esters of polyvalent carboxylic acids and monoalcohols or their (poly) oxyalkylene adducts, and esters of polyhydric alcohols or their (poly) oxyalkylene adducts.

  Specific examples include the plasticizers described in JP-A-4-335060, JP-A 2008-174718, and JP-A 2008-115372. Among these, from the viewpoint of thermoformability after storage at high temperature and transparency, preferably an ethylene oxide average adduct of 3 to 6 mol of acetic acid and glycerin (addition of 1 to 2 mol of ethylene oxide per hydroxyl group) Esters, esters of acetic acid and ethylene oxide with polyethylene glycol having an average addition mole number of 4 to 6, polyethylene glycol monomethyl ether with an average addition mole number of succinic acid and ethylene oxide of 2 to 3 (2 ethylene oxides per hydroxyl group) ~ 3 mol addition), ester of adipic acid and diethylene glycol monomethyl ether, ester of adipic acid and 1-butyl alcohol, ester of acetylcitric acid and 1-butyl alcohol, 1,3,6-hexanetricarboxylic acid Acid and diethylene glycol monomer One or more selected from the group consisting of esters with ethers, more preferably polyethylene glycol monomethyl ether having an average addition mole number of succinic acid and ethylene oxide of 2 to 3, ester of adipic acid and diethylene glycol monomethyl ether, acetyl One or more selected from the group consisting of an ester of an acid and 1-butyl alcohol is preferably used.

  The content of the plasticizer is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin, from the viewpoints of shortening the semicrystallization time of the thermoforming sheet, thermoformability, and transparency. More preferred is part by mass or more, more preferred is 1.2 parts by mass or more, from the viewpoint of improvement in glass transition temperature of the thermoforming sheet, transparency, and thermoformability after storage at high temperature, 3.5 parts by mass. Or less, more preferably 3 parts by mass or less, and even more preferably 2.5 parts by mass or less.

[Dispersant]
The dispersing agent used by this invention is not specifically limited, The dispersing agent used for general biodegradable resin is mentioned. Especially, it is preferable to contain the nonionic surfactant represented by following formula (1) from a transparency viewpoint.
R ¹ —O (A ¹ O) _p —R ² (1)
[Wherein R ¹ represents an alkyl group having 8 to 22 carbon atoms, an acyl group having 8 to 22 carbon atoms in total, or a hydrogen atom, R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, Or an acyl group having 2 to 4 carbon atoms in total, A ¹ represents an alkylene group having 2 or 3 carbon atoms, p represents an average number of added moles of an oxyalkylene group, and a number satisfying 0 <p ≦ 300 And the p oxyalkylene groups represented by (A ¹ O) may be the same or different, and if different, the repeating unit may be either a block type or a random type.

  As the compound represented by the formula (1), specifically, for example, it can be used with reference to the description in JP-A-2014-51646. Specific examples include mono- or dietherified products of aliphatic alcohols having 8 to 22 carbon atoms and polyoxyethylene glycol or polyoxypropylene glycol, or fatty acids having 8 to 22 carbon atoms and polyoxyethylene glycol or polyoxyethylene. Examples include mono- or diesterified products with oxypropylene glycol, and methyl ethers of monoesterified products of fatty acids having 8 to 22 carbon atoms with polyoxyethylene glycol or polyoxypropylene glycol. From the viewpoint of transparency, fatty acids Polyoxyethylene glycol esters and esters of fatty acids and methyl polyglycol are preferred, and esters of long-chain fatty acids such as oleic acid and polyglycol are more preferred.

  The compound represented by the formula (1) may be a commercially available product or a compound synthesized according to a known production method. Examples of suitable commercially available products include fatty acid polyoxyethylene glycol esters (for example, Emanon series such as “Emanon 4110” manufactured by Kao Corporation). Other preferable examples include polyoxyethylene-polyoxypropylene copolymers (for example, manufactured by ADEKA, trade name: Adeka Pluronic Nonion Series), which are polymer type nonions. From the viewpoint of transparency and compatibility with the polylactic acid resin at the time of melting, a so-called reverse block type adekapluronic nonion in which propylene oxide is addition-polymerized at both ends of polyoxyethylene glycol is more preferable. Specifically, examples of suitable commercial products include ADEKA Pluronic 25R-2 and 25R-1 manufactured by ADEKA.

  In the present invention, other known dispersants other than the nonionic surfactant represented by the formula (1) can be used as long as the effects of the present invention are not impaired. Although it does not specifically limit as a kind of other dispersing agent, From a viewpoint of avoiding decomposition | disassembly of the polylactic acid resin at the time of kneading | mixing, it is preferable to use surfactant other than an ionic surfactant. The content of the nonionic surfactant represented by the formula (1) in the dispersant is preferably 40% by mass or more, more preferably 60% by mass or more, and still more preferably 80% by mass or more from the viewpoint of moldability. 100% by mass is even more preferable.

  In the present invention, the dispersant is blended with a plasticizer, and the total content of the plasticizer and the dispersant is based on 100 parts by mass of the polylactic acid resin from the viewpoint of shortening the semicrystallization time of the thermoforming sheet. , 0.5 parts by mass or more, preferably 0.7 parts by mass or more, more preferably 1.0 parts by mass or more, improvement of the glass transition temperature of the thermoforming sheet, transparency, and after storage at high temperature From the viewpoint of thermoformability, it is 4.5 parts by mass or less, preferably 3.0 parts by mass or less, and more preferably 2.0 parts by mass or less.

  Further, if the total content with the plasticizer is within the above range, the dispersant may not be contained, and the content of the dispersant is not particularly limited, but the storage stability of the thermoforming sheet, for thermoforming From a viewpoint of the glass transition temperature improvement of a sheet | seat, it is 3.0 mass parts or less with respect to 100 mass parts of polylactic acid resin, 2.0 mass parts or less are preferable and 1.5 mass parts or less are more preferable. Moreover, the lower limit should just be 0 mass part or more.

[Organic crystal nucleating agent]
As the organic crystal nucleating agent in the present invention, two kinds of aliphatic amides having different structures are used. Specifically, an aliphatic amide having a hydroxyl group and having two or more amide bonds and an aliphatic amide having no hydroxyl group and having two or more amide bonds are used. In this specification, an aliphatic amide having a hydroxyl group and having two or more amide bonds is referred to as “hydroxyl group-containing aliphatic amide”, and an aliphatic amide having no hydroxyl group and having two or more amide bonds. This may be described as “a hydroxyl group-free aliphatic amide”.

  In the present invention, the above two types of aliphatic amides are used, and as a result, an effect of being excellent in thermoformability even after storage at a high temperature is exhibited. Although the detailed reason is unknown, it is presumed that the nucleating agent is stabilized by forming an association structure. However, these assumptions do not limit the present invention.

  As the hydroxyl group-containing aliphatic amide, an aliphatic compound having at least one hydroxyl group and having at least two amide bonds is preferable, and an aliphatic compound having at least two hydroxyl groups and having at least two amide bonds. Compounds are more preferred. Examples of such compounds include hydroxy fatty acid bisamides, and specific examples include methylene bis 12-hydroxystearic acid amide, ethylene bis 12-hydroxystearic acid amide, hexamethylene bis 12-hydroxystearic acid amide, and xylylene bis 12- Hydroxy stearamide is used.

  Examples of the hydroxyl amide that does not contain a hydroxyl group include fatty acid bisamides that do not have a hydroxyl group, and specific examples include ethylene bis stearic acid amide, ethylene bis oleic acid amide, and ethylene bis lauric acid amide.

  The content of the hydroxyl group-containing aliphatic amide is 0 with respect to 100 parts by mass of the polylactic acid resin from the viewpoint of shortening the semicrystallization time of the thermoforming sheet and excellent thermoformability even after storage at high temperature. 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, further preferably 0.3 parts by mass or more, and 2 parts by mass or less from the viewpoint of transparency. 0.45 parts by mass or less is preferable, and 0.40 parts by mass or less is more preferable.

  From the viewpoint of shortening the semi-crystallization time of the thermoforming sheet and excellent thermoformability even after storage at high temperature, the content of the hydroxyl-free aliphatic amide is based on 100 parts by mass of the polylactic acid resin. 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, from the viewpoint of transparency, 2 parts by mass or less, preferably 0.45 parts by mass or less, 0.40 parts by mass or less is more preferable.

  In addition, the mass ratio of the hydroxyl group-containing aliphatic amide to the hydroxyl group-free aliphatic amide (hydroxyl group-containing aliphatic amide / hydroxyl group-free aliphatic amide) is determined in view of shortening the half-crystallization time of the thermoforming sheet and at a high temperature. From the viewpoint of excellent thermoformability even after storage, it is preferably 0.1 to 10, more preferably 0.2 to 5.0, still more preferably 0.3 to 4.0, and even more. Preferably it is 0.5-2.0, More preferably, it is 0.6-1.5.

  In the present invention, other known organic crystal nucleating agents other than the hydroxyl group-containing aliphatic amide and the hydroxyl group-free aliphatic amide can be used as long as the effects of the present invention are not impaired. Although it does not specifically limit as another organic crystal nucleating agent, From the viewpoint of shortening the half crystallization time of the sheet | seat for thermoforming, the aliphatic compound or amide which has one or more hydroxyl groups and has one amide group An aliphatic compound having no group and having at least one hydroxyl group and ester group is preferred. The total content of the hydroxyl group-containing aliphatic amide and the hydroxyl group-free aliphatic amide in the organic crystal nucleating agent is a viewpoint of shortening the semicrystallization time of the thermoforming sheet and a viewpoint of excellent thermoformability even after storage at high temperature. Therefore, 40 mass% or more is preferable, 60 mass% or more is more preferable, 80 mass% or more is further more preferable, and it is still more preferable that it is 100 mass%.

  The content of the organic crystal nucleating agent is 0.2 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin from the viewpoint of shortening the semicrystallization time of the thermoforming sheet and thermoforming after storage at high temperature. Is preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, and still more preferably 0.6 parts by mass or more. Further, from the viewpoint of thermoformability after storage at high temperature and transparency, 2.0 parts by mass or less is preferable, 1.5 parts by mass or less is more preferable, and 1.0 part by mass or less is still more preferable.

[Hydrolysis inhibitor]
In the polylactic acid resin composition constituting the thermoforming sheet of the present invention, a carbodiimide compound can be used as a hydrolysis inhibitor in addition to the above components from the viewpoint of thermoforming.

  Specific examples include a monocarbodiimide compound and a polycarbodiimide compound. These can be used alone or in combination of two or more.

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, poly (1,3,3). 5-triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide and the like, and monocarbodiimide compounds include di-isopropylcarbodiimide, di-octadecylcarbodiimide, N, N′-di-2,6-diisopropylphenylcarbodiimide Etc.

  The carbodiimide compounds may be used singly or in combination of two or more in order to satisfy the durability, impact resistance and thermoformability of the molded body made of the polylactic acid resin composition. Poly (4,4′-dicyclohexylmethane carbodiimide) is obtained from carbodilite LA-1 (manufactured by Nisshinbo Chemical Co., Ltd.), poly (1,3,5-triisopropylbenzene) polycarbodiimide and poly (1,3,5-tri (Isopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide is stavaxol P and stabaxol P-100 (manufactured by Rhein Chemie), and N, N'-di-2,6-diisopropylphenylcarbodiimide is stavaxol I (Rhein Chemie). Can be purchased and used.

  The content of the hydrolysis inhibitor is preferably 0.01 parts by mass or more, based on 100 parts by mass of the polylactic acid resin, from the viewpoints of hydrolysis inhibition, thermoformability after high temperature storage, and transparency, and 0.1 mass. Part or more is more preferable, 0.15 part by weight or more is further preferable, and from the viewpoint of transparency, 5 parts by weight or less is preferable, 3 parts by weight or less is more preferable, 1 part by weight or less is still more preferable, 0.5 part by weight The following are even more preferred:

  The polylactic acid resin composition constituting the thermoforming sheet of the present invention includes a lubricant, an inorganic crystal nucleating agent, a filler (inorganic filler, organic filler), a flame retardant, and an antioxidant as components other than those described above. , UV absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, antifungal agents, antibacterial agents, foaming agents and the like can be contained within a range not impairing the effects of the present invention. Similarly, other polymer materials and other resin compositions can be contained within a range that does not impair the effects of the present invention.

  The thermoforming sheet of the present invention may be any sheet as long as it is composed of a polylactic acid resin composition containing a polylactic acid resin, a plasticizer, a dispersant, and a specific organic crystal nucleating agent in specific ratios. The composition can be prepared without particular limitation as long as it contains the above components. For example, a raw material containing a polylactic acid resin, a plasticizer, a dispersant, a specific organic crystal nucleating agent, and various additives as necessary, a sealed kneader, a single or twin screw extruder, an open roll kneader It can be prepared by melt-kneading using a known kneading machine. The raw materials can be subjected to melt kneading after being uniformly mixed in advance using a Henschel mixer, a super mixer, or the like. In order to promote the plasticity of the polylactic acid resin when preparing the polylactic acid resin composition, it may be melt-mixed in the presence of a supercritical gas, and after the melt-kneading, the melt-kneaded product is dried or dried according to a known method. It may be cooled.

  From the viewpoint of improving the moldability and prevention of deterioration of the polylactic acid resin composition, the melt kneading temperature is not less than the melting point (Tm) of the polylactic acid resin, preferably not less than Tm ° C and not more than Tm + 100 ° C, more preferably. Is a range of Tm ° C. or more and Tm + 50 ° C. or less. Specifically, for example, it is preferably 170 ° C. or higher, preferably 240 ° C. or lower, more preferably 220 ° C. or lower. The melt-kneading time cannot be generally determined depending on the melt-kneading temperature and the type of the kneader, but is preferably 15 seconds or more and 900 seconds or less. In addition, in this specification, melting | fusing point (Tm) and glass transition temperature (Tg) can be calculated | required according to the method as described in the below-mentioned Example.

  The melting point (Tm) of the polylactic acid resin composition is preferably 140 ° C. or higher, more preferably 150 ° C. or higher, further preferably 160 ° C. or higher, more preferably 220 ° C. or lower, and 210 ° C. or lower, from the viewpoint of thermoformability. More preferably, 200 degrees C or less is still more preferable.

  The glass transition temperature (Tg) of the polylactic acid resin composition is preferably 48 ° C or higher, more preferably 50 ° C or higher, still more preferably 52 ° C or higher, and preferably 60 ° C or lower, from the viewpoint of thermoformability. 58 ° C. or lower is more preferable, and 57 ° C. or lower is further preferable.

  Since the melt-kneaded product thus obtained is excellent in transparency and thermoformability, it is formed into a primary processed product comprising the polylactic acid resin composition, that is, the thermoforming sheet of the present invention.

  The thermoforming sheet of the present invention is not particularly limited as long as the polylactic acid resin composition is used, and can be prepared by extrusion molding, injection molding, or press molding.

  Specifically, in the extrusion molding, the polylactic acid resin composition filled in a heated extruder is melted and then extruded from a T die to obtain a sheet-like molded product (also referred to as a sheet molded product). be able to. The sheet molded product is immediately brought into contact with a cooling roll, cooled, separated from the cooling roll, and then wound up with a winding roll, whereby the thermoforming sheet of the present invention can be obtained. In addition, when filling the extruder, the raw material constituting the polylactic acid resin composition, for example, a polylactic acid resin, a plasticizer, a dispersant, a specific organic crystal nucleating agent, and various additives as necessary are contained. The raw materials may be filled as they are and melt-kneaded, or those previously melt-kneaded may be filled into an extruder.

  The temperature of the extruder is preferably 170 ° C. or higher, preferably 240 ° C. or lower, more preferably 220 ° C. or lower, from the viewpoint of uniformly mixing the polylactic acid resin composition and preventing deterioration of the polylactic acid resin. is there. In the present invention, the temperature of the extruder means the barrel set temperature of the extruder. Further, the residence time in the extruder cannot be defined unconditionally because it depends on the thickness, width, and winding speed of the sheet, but is preferably about 30 seconds to several minutes from the viewpoint of avoiding deterioration due to heat.

The temperature of the cooling roll is preferably set to be less than Tg of the polylactic acid resin composition from the viewpoint of obtaining a sheet in an amorphous state or a semi-crystalline state, specifically, preferably less than 40 ° C., and preferably 30 ° C. or less. More preferably, 20 degrees C or less is still more preferable. In this specification, the amorphous state and the semi-crystalline state are an amorphous state and a relative crystallinity of 60% or more and 80% when the relative crystallinity obtained by the following formula is less than 60%. The case where it is less than that is defined as a semicrystalline state. Therefore, an amorphous or semi-crystalline sheet means a sheet having a relative crystallinity of less than 80%.
Relative crystallinity (%) = {(ΔHm−ΔHcc) / ΔHm} × 100
Specifically, the relative crystallinity was raised from 20 ° C. to 200 ° C. at a rate of temperature increase of 20 ° C./min using a DSC apparatus (Diamond DSC manufactured by PerkinElmer Co., Ltd.) at a rate of temperature increase of 20 ° C./min. After holding, the temperature was lowered from 200 ° C. to 20 ° C. at a temperature drop rate of −20 ° C./min, held at 20 ° C. for 1 minute, and then further increased from 20 ° C. to 200 ° C. at a temperature rising rate of 20 ° C./min as 2ndRUN. The absolute value ΔHcc of the cold crystallization enthalpy of the polylactic acid resin observed at 1st RUN and the crystal melting enthalpy ΔHm observed at 2nd RUN can be used.

  The time for contact with the cooling roll is not necessarily specified because it varies depending on the set temperature of the cooling roll, the number of cooling rolls, the extrusion speed, and the sheet winding speed. For example, the sheet in an amorphous or semi-crystalline state can be efficiently used. From the viewpoint of obtaining the above, it is preferably 0.1 seconds or more, more preferably 0.5 seconds or more, still more preferably 0.8 seconds or more, preferably 50 seconds or less, more preferably 10 seconds or less, still more preferably 5 Less than a second. Further, from the same viewpoint, the sheet winding speed is preferably 0.1 m / min or more, more preferably 0.5 m / min or more, still more preferably 1 m / min or more, preferably 50 m / min or less, More preferably, it is 30 m / min or less, More preferably, it is 20 m / min or less.

  When molding the thermoforming sheet of the present invention by injection molding, specifically, from the viewpoint of uniformly mixing the polylactic acid resin composition and preventing deterioration of the polylactic acid resin, the polylactic acid resin composition The cylinder temperature is preferably 180 ° C. or higher, preferably 220 ° C. or lower, more preferably 210 ° C. or lower, and filled into a mold having a desired shape to form a sheet. Can be molded.

  When the thermoforming sheet of the present invention is formed by press molding, specifically, the polylactic acid resin composition is surrounded by a frame having a desired sheet shape and press-molded to form the thermoforming sheet of the present invention. Can be obtained.

  The press molding temperature and pressure are preferably 170 ° C. or higher and 240 ° C. or lower and 5 MPa or higher and 30 MPa or lower from the viewpoint of uniformly mixing the polylactic acid resin composition and preventing deterioration of the polylactic acid resin. It is preferable to press under conditions of 175 ° C. or higher and 220 ° C. or lower, 10 MPa or higher and 25 MPa or lower, more preferably 180 ° C. or higher and 210 ° C. or lower, 10 MPa or higher and 20 MPa or lower. Although the press time cannot be determined unconditionally depending on the temperature and pressure of the press, from the viewpoint of uniform mixing, it is preferably 1 minute or more, preferably 10 minutes or less, more preferably 7 minutes or less, and still more preferably. 5 minutes or less.

  In addition, immediately after pressing under the above conditions, preferably 0 ° C. or higher and 40 ° C. or lower, 0.1 MPa or higher and 20 MPa or lower, more preferably 10 ° C. or higher and 30 ° C. or lower, 0.1 MPa or higher and 10 MPa or lower, further preferably Is preferably pressed and cooled under conditions of 10 to 20 ° C. and 0.1 to 5 MPa. By pressing under this temperature condition, the polylactic acid resin composition in the present invention can be cooled to less than its Tg to maintain an amorphous state or a semi-crystalline state. Although the press time cannot be determined unconditionally depending on the temperature and pressure of the press, from the viewpoint of cooling efficiency and productivity, it is preferably 1 minute or more, preferably 10 minutes or less, more preferably 7 minutes or less, More preferably, it is 5 minutes or less.

  Thus, the thermoforming sheet of the present invention is obtained. From the viewpoint of moldability, the thickness of the thermoforming sheet is preferably 0.1 mm or more, more preferably 0.2 mm or more, preferably 1.5 mm or less, more preferably 1.4 mm or less, and still more preferably. It is 1.2 mm or less.

  Further, the glass transition temperature of the thermoforming sheet of the present invention is preferably 50 ° C. or higher, more preferably 51 ° C. or higher, further preferably 52 ° C. or higher, preferably 60 ° C., from the viewpoints of storage stability and moldability. ° C or lower, more preferably 59 ° C or lower, still more preferably 58 ° C or lower.

  The half crystallization time of the thermoforming sheet of the present invention is preferably 5 seconds or more, more preferably 8 seconds or more, still more preferably 10 seconds or more, preferably 30 seconds or less, more preferably from the viewpoint of moldability. Is 27 seconds or less, more preferably 25 seconds or less. In the present specification, the half crystallization time can be determined according to the method described in Examples described later.

  The sheet for thermoforming of the present invention is preferably obtained in an amorphous state or a semi-crystalline state from the viewpoint of formability, and therefore the relative crystallinity obtained by the above formula is preferably less than 80%, more Preferably it is less than 60%, more preferably less than 50%. The lower limit is not particularly set, but may be 0% or more.

  Moreover, this invention provides the manufacturing method of the sheet | seat for thermoforming of this invention. Specifically, there is no particular limitation as long as it includes the step of preparing the thermoforming sheet of the present invention, in addition to the manufacturing method of winding with a winding roll, after cooling with a cooling roll, Examples thereof include a method of producing sheets in a stacked state while cutting into lengths, and a continuous forming method in which a sheet for thermoforming is sent to a thermoforming machine as it is without forming a roll. In particular, from the viewpoint of productivity, sheet storage, and subsequent transportation, a manufacturing method for forming a roll in the “winding step” is performed. As a cooling method, in addition to the method of contacting the cooling roll, contact with a metal plate for cooling, blowing of cooled air (air knife), cooling water tank, and the like can be used. In addition, for example, contact with a metal roll for temperature adjustment, contact with a metal plate for temperature adjustment, blowing of air for temperature adjustment (air knife), temperature adjustment tank with infrared rays, heat ray heater, etc. are used. You can also

  Specifically, for example, “extrusion / cooling step” in which the sheet extruded from the T die is melted and kneaded in an extruder, and then extruded from the T die is cooled by a cooling roll, and then a certain tension or It includes a “winding step” that winds up into a roll at a constant winding speed. Depending on the environment of the manufacturing site and the time of manufacture, the surface temperature of the sheet may rise during the winding process. Stretching occurs. The sheet thus obtained has a negative effect on the subsequent thermoformability (moldable temperature range) because the phase difference of the sheet increases due to being slightly stretched. Therefore, it is preferable to adjust (cool) the sheet surface temperature low in order to suppress an excessive temperature rise in the winding process, and for good thermoforming by setting the sheet surface temperature to 0 to 50 ° C. in the winding process. A sheet can be manufactured. The sheet surface temperature can be measured using a contact type or non-contact type thermometer. The melt kneading conditions, cooling conditions, and winding conditions are as described above.

  Since the thermoforming sheet of the present invention thus obtained has good thermoformability, it is used in various applications, for example, packaging materials for daily necessities, cosmetics, home appliances, blister packs, trays, lunch box lids, etc. It can be thermoformed into food containers, industrial trays used for transportation and protection of industrial parts. Therefore, this invention also provides the thermoformed body formed by shape | molding the sheet | seat for thermoforming of this invention.

  The thermoformed body of the present invention is not particularly limited as long as the thermoformed sheet of the present invention is thermoformed, and the forming method is not particularly limited, and can be performed according to a known method. For example, a sheet formed by vacuum forming or pressure forming the thermoforming sheet of the present invention can be mentioned.

As a suitable aspect of the manufacturing method of the thermoformed body of this invention, the manufacturing method of the thermoformed body containing the following process (1) and (2) is mentioned.
Step (1): 0.05 parts by mass or more and 2 parts by mass or less of an aliphatic amide having a hydroxyl group and having two or more amide bonds with respect to 100 parts by mass of the polylactic acid resin, and a hydroxyl group The aliphatic amide having two or more amide bonds is contained in an amount of 0.05 to 2 parts by mass, and the total content of the plasticizer and the dispersant is 0.5 to 4.5 parts by mass. A process step (2) of heating a thermoforming sheet comprising a polylactic acid resin composition containing not more than parts by mass within a temperature range not lower than the glass transition temperature (Tg) and lower than the melting point (Tm) of the polylactic acid resin composition. : Thermoforming the sheet obtained in step (1) using a mold having a mold temperature of 60 ° C or higher and 140 ° C or lower.

  The thermoforming sheet used in step (1) is the thermoforming sheet of the present invention, and the constituent components and content thereof are the same as described above. Further, since it is necessary to soften the thermoforming sheet in an amorphous state by heating in the step (1), the sheet surface temperature is set to a glass transition temperature (Tg) or higher of the polylactic acid resin composition, a melting point ( Tm) is necessary. The heating temperature of the thermoforming sheet is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 65 ° C. or higher, preferably 120 ° C. or lower, more preferably 100 ° C. or lower, still more preferably 90 ° C. or lower. It is.

  In step (2), thermoforming is performed using a mold having a desired shape. Specifically, for example, the thermoforming sheet heated in step (1) is placed in a mold in a vacuum / pressure forming machine as it is, and the inside of the mold is heated to a predetermined temperature to be pressurized or not applied. By maintaining the pressure state, a molded body obtained by vacuum forming or pressure forming is obtained. The mold temperature is 60 ° C. or higher, preferably 70 ° C. or higher, more preferably 75 ° C. or higher, more preferably 80 ° C. or higher, from the viewpoint of improving the crystallization speed and workability of the polylactic acid resin composition. From the same viewpoint, it is 140 ° C. or lower, preferably 120 ° C. or lower, more preferably 115 ° C. or lower, and further preferably 110 ° C. or lower. From the viewpoint of improving the heat resistance and productivity of the thermoformed article made of the polylactic acid resin composition, the holding time in the mold is preferably 2 seconds or more and 60 seconds or less in a 90 ° C. mold, for example, 3 seconds. It is more preferably 30 seconds or less and more preferably 5 seconds or more and 20 seconds or less. In a mold at 100 ° C., it is preferably 2 seconds or more and 60 seconds or less, more preferably 3 seconds or more and 30 seconds or less, and more preferably 5 seconds or more and 20 seconds or less. The following is more preferable, and more preferably 5 seconds or longer and 15 seconds or shorter. Since the polylactic acid resin composition in the present invention has a high crystallization rate, a molded product having sufficient heat resistance can be obtained even with a short holding time as described above. The mold temperature referred to here is preferably the set temperature of the upper mold, and the set temperature of the lower mold may be the same as or different from the upper mold, The temperature is preferably lower, for example, 10 ° C. or higher and 30 ° C. or lower.

  The thermoformed article of the present invention thus obtained has excellent fitability, high crystallinity, excellent heat resistance and transparency because the thermoforming sheet of the present invention has good thermoformability. Is.

  The thickness of the thermoformed product of the present invention is not particularly limited, but from the viewpoint of obtaining a uniform formed product (secondary processed product), it is preferably 0.1 mm or more, more preferably 0.15 mm or more, still more preferably 0.00. It is 2 mm or more, preferably 1.5 mm or less, more preferably 1.4 mm or less, and still more preferably 1.2 mm or less.

  The Haze value of the thermoformed article of the present invention is preferably 0.1% or more, more preferably 0.2% or more, still more preferably 0.3% or more from the viewpoint of heat resistance, and from the viewpoint of transparency. Preferably, it is 8.0% or less, more preferably 7.0% or less, and still more preferably 6.5% or less. In the present specification, the Haze value is an index of transparency, and can be measured by the method described in Examples described later.

  Moreover, the relative crystallinity of the thermoformed article of the present invention is preferably 80% or more, more preferably 90% or more when the thermoforming sheet of the present invention immediately after preparation is used. There is no particular upper limit.

  The secondary processing method for the thermoforming sheet of the present invention is not particularly limited as long as it is a method for preparing the molded body by molding the sheet, and is as described above.

  The thus obtained thermoformed article of the present invention is excellent in heat resistance because of its high crystallinity, and also because of its excellent transparency, bleed resistance, and strength. As packaging materials for cosmetics, home appliances, etc., it can be suitably used for blister packs and trays, food containers such as lunch box lids, and industrial trays used for transport and protection of industrial parts.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. The parts in the examples are parts by mass unless otherwise specified. “Normal pressure” indicates 101.3 kPa, and “normal temperature” indicates 25 ° C.

[Melting point, glass transition temperature of polylactic acid resin composition]
Using the differential scanning calorimeter “DSC8500” (manufactured by PerkinElmer), the inflection point of 2ndRUN measured under the following measurement conditions is defined as the glass transition temperature (Tg). The peak top of the endothermic peak observed at around 160 ° C. is defined as the melting point (Tm).
Measurement conditions: Weigh about 10 mg of sample in a standard aluminum pan manufactured by PerkinElmer, set the prepared aluminum pan on DSC8500, raise the temperature from 25 ° C. to 200 ° C. at 15 ° C./min, and hold at 200 ° C. for 1 minute. (1stRUN). Then, after cooling from 200 ° C. to 25 ° C. at 500 ° C./min, the temperature is raised from 25 ° C. to 200 ° C. at a rate of 15 ° C./min (2ndRUN).

Production Example 1 of Plasticizer (Diester Compound of Succinic Acid and Triethylene Glycol Monomethyl Ether)
A four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube and nitrogen blowing tube) was charged with 363 g (3.42 mol) of diethylene glycol and 6.6 g of a methanol solution containing 28% by weight sodium methoxide as a catalyst (sodium methoxide 0). 0.034 mol) was added, and methanol was distilled off while stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 1000 g (6.84 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 3 hours, and methanol produced by the reaction was distilled off at normal pressure and 120 ° C. Next, the mixture was cooled to 75 ° C., the pressure was gradually reduced from normal pressure to 6.7 kPa over 1.5 hours to distill off methanol, and the pressure was returned to normal pressure. Further, 28% by mass sodium methoxide as a catalyst was obtained. A methanol solution containing 5.8 g (sodium methoxide 0.030 mol) was added, and the pressure was gradually reduced from normal pressure to 2.9 kPa over 2 hours at 100 ° C. to distill methanol. Then, after cooling to 80 ° C., 18 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred at a pressure of 4.0 kPa and 80 ° C. for 1 hour, followed by filtration under reduced pressure. The filtrate was pressured at 0.3 kPa and the temperature was raised from 70 ° C. to 190 ° C. over 1 hour to distill off the remaining dimethyl succinate to obtain a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.94 mol with respect to 100 mol of dicarboxylic acid ester.

Examples 1-13 and Comparative Examples 1-7
Preparation of Polylactic Acid Resin Composition As a polylactic acid resin composition, the composition raw materials shown in Tables 1 to 3 were mixed with a twin screw extruder “HK-25D” (manufactured by PARKER) for 10 minutes at a rotation speed of 90 r / min. Then, melt kneading was performed at a melt kneading temperature of 180 to 190 ° C., strand cutting was performed, and pellets of the polylactic acid resin composition were obtained. The obtained pellets were dried at 70 ° C. under reduced pressure for 1 day, and the water content was adjusted to 500 ppm or less.

Preparation of thermoforming sheet A square spacer (thickness 0.25 mm, width 1 cm, one side inside) between two 0.5 mm thick stainless steel plates (made by ASANUMA & CO. LTD, Ferrotype Plate Deluxe) with hard chrome plating finish 20 cm), and 15 g of the kneaded pellets are filled inside and pressed using an auto press molding machine (manufactured by Toyo Seiki Co., Ltd.) at a press temperature of 185 ° C. and a press pressure of 0.4 MPa for 180 minutes. , And further pressed at 20 MPa for 2 minutes. Thereafter, the sheet was immediately cooled to 0.4 MPa with a press plate set at 15 ° C. for 1 minute to obtain a thermoforming sheet (amorphous sheet) having a constant thickness (thickness 0.25 mm).

Preparation of Thermoformed Body Next, the thermoforming sheet was attached to a guide using a single vacuum / pressure forming machine “FVS-500P WAKITEC” (manufactured by Wakisaka Seisakusho Co., Ltd.), and a thermoforming sheet was prepared using a heater. Heated to ° C. Thereafter, the heated thermoforming sheet was vacuum-formed using upper and lower molds set to an upper mold of 100 ° C. and a lower mold of 25 ° C., and held in the mold for 5 seconds to obtain a molded body (thickness). 0.23 mm). The sheet surface temperature was measured by directly measuring the sheet surface temperature after heating with a surface thermometer. The mold (lid) used is shown in FIG.

  The characteristics of the obtained thermoforming sheet and thermoformed body were evaluated according to the following Test Examples 1 to 5. Moreover, about the obtained sheet | seat for thermoforming, after winding with 2 kg of force on the paper core (made by Oka packaging material, internal diameter 76.2mm, thickness 10mm, length 300mm), various temperature (40 degreeC, 42 degreeC, A thermoformed article was prepared according to the above molding method and evaluated in the same manner as described above in a constant temperature and humidity machine (LHL-113 manufactured by ESPEC) set at 45 ° C. The results are shown in Tables 1-3. In addition, the result of the sample which was not able to be evaluated was shown as "impossible".

Test Example 1 <Glass transition temperature>
Using a differential scanning calorimeter “DSC8500” (manufactured by PerkinElmer), the inflection point of 2ndRUN measured under the following measurement conditions was defined as the glass transition temperature (Tg). It shows that it is excellent in heat resistance, so that a glass transition temperature is high.
Measurement conditions: About 10 mg of thermoforming sheet is measured on a standard aluminum pan manufactured by PerkinElmer, set on DSC8500, heated from 25 ° C. to 200 ° C. at 15 ° C./min, and then held at 200 ° C. for 1 minute ( 1stRUN). Then, after cooling from 200 ° C. to 25 ° C. at 500 ° C./min, the temperature is raised from 25 ° C. to 200 ° C. at a rate of 15 ° C./min (2ndRUN).

Test Example 2 <Semi-crystallization time>
Using a differential scanning calorimeter “DSC8500” (manufactured by PerkinElmer), the amount of time required for 50% crystallization to proceed is calculated from the amount of heat measured under the following measurement conditions. Time (seconds) was used. The shorter the half crystallization time, the better the crystallization speed.
Measurement conditions: About 10 mg of thermoforming sheet is weighed on a standard aluminum pan manufactured by PerkinElmer, set on DSC8500, heated from 25 ° C. to 90 ° C. at 500 ° C./min, and then held at 90 ° C. for 10 minutes.

Test Example 3 <Thermoformability>
The shape and fit of the molded body were evaluated according to the following methods. In addition, a molded object standard is a lid | cover of the container (brand name Yugaku 90 Shino CPP Kasei Co., Ltd.) of a commercial item. It is preferably 2 or more, more preferably 3 or more, based on evaluation criteria.
Shape: The shape of the obtained molded body was visually compared with the shape of the molded body specimen molded with the mold (lid) of FIG. 1 and evaluated according to the following evaluation criteria.
Fitting property: It was fitted to a main body part (φ81 mm, height 51 mm, material made of low foamed PS containing PP) of a commercially available container (trade name: Yubumimi 90, Shino CPC Kasei Co., Ltd.) and evaluated according to the following evaluation criteria.
〔Evaluation criteria〕
4: It is the same shape as a molded object standard, and can be fitted without applying a load.
3: It is the same shape as a molded object standard, and can be fitted by applying a load.
2: It has almost the same shape as the molded product, and can be barely fitted.
1: The shape is clearly different from the molded product or does not fit.

Test Example 4 <Crystallinity>
About 7.5 mg of each of the thermoforming sheet and the thermoformed body that can be fitted by the above-described fitting evaluation, sealed in an aluminum pan, and then a differential scanning calorimeter “DSC8500” (manufactured by PerkinElmer) As 1stRUN, the temperature was increased from 25 ° C. to 200 ° C. at a temperature increase rate of 15 ° C./min, held at 200 ° C. for 1 minute, and then decreased from 200 ° C. to 25 ° C. at a temperature decrease rate of −500 ° C./min. After maintaining at 20 ° C. for 1 minute, the temperature was further increased from 25 ° C. to 200 ° C. at a temperature increase rate of 15 ° C./min as 2nd RUN, and then the absolute value ΔHc of the cold crystallization enthalpy of the polylactic acid resin observed at 1st RUN, The crystal melting enthalpy ΔHm observed at 2ndRUN was determined, and from the obtained value, the relative crystallinity (%) was determined by the following formula, and the crystallinity was evaluated. When the relative crystallinity is less than 60%, it is in an amorphous state, when it is 65% or more and less than 80%, it is in a semi-crystalline state, and when it is 80% or more, it is in a crystalline state.
Relative crystallinity (%) = {(ΔHm−ΔHc) / ΔHm} × 100

Test Example 5 <Transparency>
A part of the molded product that could be fitted in the fitting evaluation was cut out, and a haze value (%) was measured using a haze meter “HM-150 type” (Murakami Color Research Laboratory Co., Ltd.). Was used as an index of transparency. It shows that it is excellent in transparency, so that the value of Haze value is small.

In addition, the raw material in Tables 1-3 is as follows.
[Polylactic acid resin]
NW4032D: Poly-L-lactic acid (optical purity 98.5%), manufactured by Nature Works [Plasticizer]
(MeEO ₃ ) ₂ SA: Diester compound produced in Production Example 1 of the plasticizer DAIFATTY-101: Adipic acid ester, Daihachi Chemical Industries, Ltd. ATBC: Tributyl acetylcitrate, Taoka Chemical Industries [Organic crystal nucleating agent ]
(Aliphatic amide having a hydroxyl group and having two or more amide bonds)
SLIPAX H: N, N′-ethylene-bis-12-hydroxystearic acid amide, Nippon Kasei Co., Ltd. ITOWAX J-630: N, N′-hexamethylene-bis-12-hydroxystearic acid amide, manufactured by Ito Oil Co., Ltd. ( Aliphatic amides with no hydroxyl groups and two or more amide bonds)
Kao Wax EB-FF: Ethylene bis stearamide, Sripax O manufactured by Kao Corporation: Ethylene bis oleic acid amide, Sripax L manufactured by Nippon Kasei Co., Ltd .: Ethylene bis lauric acid amide, manufactured by Nippon Kasei Co., Ltd.
ITOWAX J-420: N-hydroxyethyl-12-hydroxystearic acid amide, manufactured by Ito Oil Co., Ltd. [Dispersant]
Adekapluronic 25R-2: polyoxyethylene-polyoxypropylene copolymer, manufactured by ADEKA, average molecular weight 3,500, R ¹ and R ² in formula (1) are hydrogen atoms, (A ¹ O) _p is polyoxypropylene -Compound Emanone 4110 which is a block type of polyoxyethylene-polyoxypropylene type, wherein p 'of the polyoxypropylene group is 47, p' of the polyoxyethylene group is 16, and the total p in formula (1) is 63: Oleic acid polyoxyethylene glycol monoester, manufactured by Kao Corporation, average molecular weight 680, R ¹ in formula (1) is an unsaturated acyl group derived from oleic acid, R ² is a hydrogen atom, A ¹ is an ethylene group, p is 9 Certain compounds [hydrolysis inhibitors]
Carbodilite LA-1: Aliphatic polycarbodiimide compound, manufactured by Nisshinbo Chemical Co., Ltd.

  From the results of Tables 1 to 3, the thermoforming sheet of the present invention is excellent in thermoforming even after storage at a high temperature, and the obtained thermoformed article exhibits higher crystallinity than the sheet and is good. It had excellent transparency and good appearance.

Test Example 6 <Semi-crystallization time after high temperature storage>
About the sheet | seat for thermoforming of Example 3 and Comparative Example 1, it puts into the set thermostat and humidity machine set to 45 degreeC (LHL-113 by ESPEC), left still, and is sampled with time, and is the same as that of Test Example 2 Then, the half crystallization time (second) was calculated. The results are shown in Table 4 and FIG.

  From Table 4, it can be seen that the thermoforming sheet of Example 3 is excellent in storage stability at high temperatures, with no change in storage time and half-crystallization time even when stored at 45 ° C. for 72 hours.

  Since the thermoforming sheet of the present invention has high thermoformability, it can be suitably used for various applications such as food containers, packaging materials for daily necessities and home appliances, and trays for industrial parts.

Claims (6)

In a polylactic acid resin, 0.05 mass part or more and 2 mass parts or less of an aliphatic amide having a hydroxyl group and having two or more amide bonds with respect to 100 mass parts of the polylactic acid resin, and 2 having no hydroxyl group Containing 0.05 to 2 parts by mass of an aliphatic amide having one or more amide bonds, and 0.5 to 4.5 parts by mass in total of a plasticizer and a dispersant. A sheet for thermoforming comprising the polylactic acid resin composition , wherein the plasticizer content is 0.5 parts by mass or more and 3.5 parts by mass or less with respect to 100 parts by mass of the polylactic acid resin, and the dispersion The sheet | seat for thermoforming whose content of an agent is 0 to 3.0 mass parts .   The content of the aliphatic amide having a hydroxyl group and having two or more amide bonds is 0.1 to 0.45 parts by mass, and the aliphatic amide having no hydroxyl group and having two or more amide bonds The thermoforming sheet according to claim 1, wherein the amount is from 0.1 parts by mass to 0.45 parts by mass.   The thermoforming sheet according to claim 1 or 2, wherein the total content of the plasticizer and the dispersant is 0.5 parts by mass or more and 3.0 parts by mass or less.   The thermoformed sheet according to any one of claims 1 to 3, wherein the plasticizer contains a compound having two or more ester groups in the molecule. The thermoforming sheet according to any one of claims 1 to 4, wherein the dispersant contains a compound represented by the following formula (1).
R ¹ —O (A ¹ O) _p —R ² (1)
[Wherein R ¹ represents an alkyl group having 8 to 22 carbon atoms, an acyl group having 8 to 22 carbon atoms in total, or a hydrogen atom, R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, Or an acyl group having 2 to 4 carbon atoms in total, A ¹ represents an alkylene group having 2 or 3 carbon atoms, p represents an average number of added moles of an oxyalkylene group, and a number satisfying 0 <p ≦ 300 And the p oxyalkylene groups represented by (A ¹ O) may be the same or different, and if different, the repeating unit may be either a block type or a random type. A method for producing a thermoformed article comprising the following steps (1) and (2).
Step (1): A step of heating the thermoforming sheet according to any one of claims 1 to 5 within a temperature range not lower than the glass transition temperature (Tg) and lower than the melting point (Tm) of the polylactic acid resin composition (2). ): A step of thermoforming the sheet obtained in step (1) using a mold having a mold temperature of 60 ° C. or higher and 140 ° C. or lower.

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