WO2015119155A1 - Polylactic acid resin sheet for thermoforming - Google Patents

Abstract

　Provided is a sheet for thermoforming which is formed from a polylactic acid resin composition prepared by adding 0.5-3.5 parts by mass of a plasticizer and 0.15-0.45 parts by mass of an organic nucleating agent to 100 parts by mass of a polylactic acid resin. Also provided are a production method for the sheet, a molded article obtained by forming the sheet, a production method for the molded article, and a method for machining the sheet. The sheet for thermoforming according to the present invention exhibits excellent thermoforming properties, and thus is suitable for various uses, including use in food containers and in trays for industrial components, and use as a packaging material for household goods and appliances.

Description

Polylactic acid resin sheet for thermoforming

The present invention relates to a polylactic acid resin sheet for thermoforming. More specifically, 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., a method for producing the sheet, a molded article formed by molding the sheet, and the production thereof The present invention relates to a method and a method for processing the sheet.

Polylactic acid resin is inexpensive because L-lactic acid as a raw material is produced by fermentation using sugars 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, 100 parts by weight of a lactic acid polymer (A), 0.1 to 3 parts by weight of an organic crystal nucleating agent (B) containing an aliphatic carboxylic acid amide having an amide bond, and a crystallization accelerator ( C) A sheet made of a lactic acid polymer composition containing 0.1 to 7 parts by weight is thermoformed at a temperature of 60 to 130 ° C. to obtain a molded body having transparency and heat resistance with excellent production efficiency. Has been reported.

Further, Patent Document 2 discloses that shaping in thermoforming while maintaining transparency by combining a specific organic crystal nucleating agent and a specific nonionic surfactant in addition to a plasticizer in a polylactic acid resin. It is described that a polylactic acid resin composition can be obtained which can achieve both compatibility and crystallization, that is, thermoformability is remarkably improved.

International Publication No. 2006/121056 JP 2012-180512 A

Summary of invention

The present invention relates to the following [1] to [7].
[1] Polylactic acid containing 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. A thermoforming sheet comprising a resin composition.
[2] A method for producing a thermoforming sheet comprising the following steps (A) and (B).
Step (A): The polylactic acid resin contains 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Step (B) for preparing a sheet molded product by extruding the polylactic acid resin composition to be extruded by an extruder having a temperature of 170 to 240 ° C .: Cooling the sheet molded product obtained in the step (A) at a temperature of less than 40 ° C. Step [3] for cooling by contact with rolls A method for producing a thermoformed article comprising the following steps (1) and (2).
Step (1): Step (2) of heating the thermoforming sheet described in [1] above within a temperature range not lower than the glass transition temperature (Tg) of the sheet and lower than the melting point (Tm). Step of thermoforming the obtained sheet using a mold having a mold temperature of 60 to 140 ° C. [4] A molded body obtained by vacuum forming or pressure forming the thermoforming sheet of [1].
[5] A secondary processing method for a sheet, comprising vacuum forming or pressure forming the thermoforming sheet according to [1].
[6] A packaging material comprising the molded article according to [4].
[7] A thermoforming sheet having a glass transition temperature of 50 to 60 ° C., a half-crystallization time of 5 to 27 seconds, and a Haze value of the obtained thermoformed article of 0.1 to 8.0%.

FIG. 1 is a view showing a molding die used in Examples.

Detailed Description of the Invention

As a resin that can replace various plastics, the conventional polylactic acid resin needs further improvement. 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 major problem that thermoformability deteriorates due to storage at a relatively high temperature (30 to 40 ° C.), such as storage in a warehouse in summer.

The present invention provides a thermoforming sheet comprising a polylactic acid resin composition having good thermoformability even after storage at a relatively high temperature in summer, a molded article formed by molding the sheet, and a method for producing the same And a processing method of the sheet.

Since the thermoforming sheet of the present invention is excellent in thermoformability, in particular, thermoformability even after storage at high temperature, 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.

As a result of intensive studies in view of such a situation, the inventors of the present invention combined a specific amount of a plasticizer and a specific amount of an organic crystal nucleating agent with a polylactic acid resin, so that thermoformability even after storage at high temperatures. The present inventors have found that a thermoforming sheet excellent in resistance can be obtained, and have completed the present invention.

One feature of the thermoforming sheet of the present invention is that it comprises a polylactic acid resin composition containing a specific additive, that is, a specific amount of a plasticizer and a specific amount of an organic crystal nucleating agent in addition to the polylactic acid resin. Have

[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.

Further, 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 low molecular weight compounds by microorganisms in nature, and specifically, JIS K6953 (ISO 14855) “controlled aerobic composting conditions. This means biodegradability based on the “Aerobic and Ultimate Biodegradation and Disintegration Test”.

The content of the polylactic acid resin is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more in the polylactic acid resin composition from the viewpoint of biodegradability.

[Plasticizer]
The plasticizer used by this invention is not specifically limited, The plasticizer used for general biodegradable resin is mentioned. Among these, from the viewpoint of thermoformability and transparency after storage at high temperature, a compound having two or more ester groups in the molecule is preferable, and the molecule has two or more ester groups per molecule. Compounds having an average addition mole number of ethylene oxide of preferably 2 to 9, more preferably 3 to 9, are more preferred. Such compounds include esters of polyvalent carboxylic acids and monoalcohols or their (poly) oxyalkylene adducts, and monovalent carboxylic acids or polyvalent carboxylic acids and polyhydric alcohols or their (poly) oxyalkylene additions. Examples include esters with products.

Specifically, for example, plasticizers described in JP-A-2008-174718 and JP-A-2008-115372 can be mentioned. Among them, preferably an ester of acetic acid and glycerin with an average of 3 to 6 moles of ethylene oxide adduct (addition of 1 to 2 moles of ethylene oxide per hydroxyl group), an average number of moles of acetic acid and ethylene oxide added of 4 to 6 An ester with polyethylene glycol, an ester with polyethylene glycol monomethyl ether having an average addition mole number of succinic acid and ethylene oxide of 2 to 3 (addition of 2 to 3 moles of ethylene oxide per hydroxyl group), adipic acid and diethylene glycol monomethyl ether One selected from the group consisting of: esters of adipic acid and 1-butyl alcohol, esters of acetylcitric acid and 1-butyl alcohol, and esters of 1,3,6-hexanetricarboxylic acid and diethylene glycol monomethyl ether More preferably, from the group consisting of 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, ester of acetyl citric acid and 1-butyl alcohol One or more selected are preferably used.

The content of the plasticizer is 0.5 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin, from the viewpoints of thermoformability, transparency, and semi-crystallization time of the thermoforming sheet. More than mass part is preferable, 1.2 parts by mass or more is more preferable, from the viewpoint of improvement of glass transition temperature of the thermoforming sheet, transparency, and thermoformability after storage at high temperature, 3.5 parts by mass or less. 3 parts by mass or less is preferable, and 2.5 parts by mass or less is more preferable.

[Organic crystal nucleating agent]
The organic crystal nucleating agent used in the present invention is not particularly limited, and examples thereof include organic crystal nucleating agents used for general biodegradable resins. Among them, from the viewpoint of transparency and thermoformability after storage at high temperature, the organic crystal nucleating agent molecule is combined with one or more groups selected from the group consisting of an ester group, a hydroxyl group, and an amide group. An aliphatic compound having two or more is preferable. For example, alkylene bis fatty acid amide, alkylene bis hydroxy fatty acid amide, etc. are mentioned. Among these, from the viewpoints of transparency of the thermoforming sheet, shortening of the semicrystallization time, and thermoformability after storage at high temperature, it has one or more hydroxyl groups and one ester group or amide group. Preferred are aliphatic compounds having more than one, more preferred are aliphatic compounds having two or more hydroxyl groups, and one or more ester groups or amide groups, and having two or more hydroxyl groups, and are ester groups or amide groups. An aliphatic compound having two or more is more preferable.

The aliphatic compound having a hydroxyl group and an amide group in the organic crystal nucleating agent molecule is preferably an aliphatic amide having a hydroxyl group. Specific examples include hydroxy fatty acid monoamides such as 12-hydroxystearic acid monoethanolamide, methylene bis 12- Examples thereof include hydroxy fatty acid bisamides such as hydroxy stearic acid amide, ethylene bis 12-hydroxy stearic acid amide, and hexamethylene bis 12-hydroxy stearic acid amide.

The content of the organic crystal nucleating agent is based on 100 parts by mass of the polylactic acid resin from the viewpoint of thermoformability of the thermoforming sheet, transparency, shortening of the semicrystallization time, and thermoformability after storage at high temperature. 0.15 parts by mass or more, preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and further preferably 0.33 parts by mass or more. In addition, from the viewpoint of thermoformability of the thermoforming sheet, shortening of the semicrystallization time, and thermoformability after storage at high temperature, it is 0.45 parts by mass or less, preferably 0.4 parts by mass or less, 0.38 parts by mass or less is more preferable.

In the present invention, it is preferable to use two kinds of aliphatic amides having different structures as the organic crystal nucleating agent. Specific examples include 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. By using the two types of aliphatic amides, the nucleating agent forms an associated structure and stabilizes, and the effect of excellent thermoformability is exhibited even after storage at high temperatures. 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”.

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-hydroxy stearic acid amide, ethylene bis 12-hydroxy stearic acid amide, hexamethylene bis 12-hydroxy stearic acid amide, xylylene bis 12- Hydroxy stearamide is used.

Examples of the hydroxyl group-free aliphatic amide include fatty acid bisamide having no 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 not particularly limited as long as the total content as the organic crystal nucleating agent is 0.15 parts by mass or more and 0.45 parts by mass or less, but the semi-crystal of the thermoforming sheet From the viewpoint of shortening the formation time and from the viewpoint of excellent thermoformability even after storage at high temperature, 0.05 part by mass or more is preferable, and 0.1 part by mass or more is more preferable with respect to 100 parts by mass of the polylactic acid resin. From the viewpoint of transparency, 0.40 parts by mass or less is preferable.

The content of the hydroxyl group-free aliphatic amide is not particularly limited as long as the total content as the organic crystal nucleating agent is 0.15 parts by mass or more and 0.45 parts by mass or less. From the viewpoint of shortening the crystallization time and from the viewpoint of excellent thermoformability even after storage at a high temperature, 0.05 parts by mass or more is preferable with respect to 100 parts by mass of the polylactic acid resin, and 0.1 parts by mass or more is more preferable. From the viewpoint of transparency, 0.40 parts by mass or less is 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 to 2.0, and more preferably 0.6 to 1.5.

In the present invention, the other organic crystal nucleating agent used in combination with the hydroxyl group-containing aliphatic amide and the hydroxyl group-free aliphatic amide is not particularly limited, but from the viewpoint of shortening the half-crystallization time of the thermoforming sheet. An aliphatic compound having one or more hydroxyl groups and one amide group or an aliphatic compound having no amide group and one or more hydroxyl groups and ester groups 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%.

[Nonionic surfactant]
In addition to polylactic acid resin, plasticizer, and organic crystal nucleating agent, the polylactic acid resin composition constituting the thermoforming sheet of the present invention is a non-ion represented by the following formula (1) from the viewpoint of transparency. It is preferable to contain a surfactant.
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, or a hydrogen atom, and R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a total carbon atom. An acyl group having a number of 2 to 4, A ¹ represents an alkylene group having 2 or 3 carbon atoms, p represents an average number of moles added of the oxyalkylene group, and 0 <p ≦ 300, The p oxyalkylene groups represented by A ¹ O) may be the same or different, and the repeating unit in different cases may be either a block type or a random type.

R ¹ in Formula (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.

The alkyl group having 8 to 22 carbon atoms may be linear or branched, saturated or unsaturated, and specifically includes an octyl group, nonyl group, decyl group, undecyl group, dodecyl group. Linear alkyl groups such as a group (lauryl group), tridecyl group, tetradecyl group (myristyl group), pentadecyl group, hexadecyl group (cetyl group), heptadecyl group, octadecyl group (stearyl group), nonadecyl group, eicosyl group, behenyl group In addition to branched alkyl groups such as 2-ethylhexyl group, 2-hexyldecyl group, isodecyl group and isostearyl group, unsaturated alkyl groups such as undecenyl group and oleyl group. The acyl group having 8 to 22 carbon atoms may be saturated or unsaturated as long as the total carbon number is 8 to 22. Octanoyl group, nonanoyl group, decanoyl group, undecanoyl group, dodecanoyl group (lauroyl group) In addition to linear acyl groups such as tridecanoyl group, tetradecanoyl group, pentadecanoyl group, hexadecanoyl group, heptadecanoyl group, octadecanoyl group, nonadecanoyl group, eicosanoyl group, and behenoyl group, 2-ethylhexanoyl group Examples thereof include branched acyl groups such as oleic acid and unsaturated acyl groups derived from oleic acid.

R ² in Formula (1) 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.

The alkyl group having 1 to 4 carbon atoms may be linear or branched, and specifically includes methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl. Groups. The acyl group having 2 to 4 carbon atoms may be saturated or unsaturated, and specific examples include an acetyl group, a propanoyl group, and a butanoyl group.

Among these, R ² in the formula (1) is, when R ¹ is an alkyl group having 8 to 22 carbon atoms or an acyl group having 8 to 22 carbon atoms, from the viewpoint of molding temperature range and transparency. , A hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable. When R ¹ in formula (1) is a hydrogen atom, R ² is also preferably a hydrogen atom.

A ¹ in Formula (1) represents an alkylene group having 2 or 3 carbon atoms, and A ¹ O represents an oxyalkylene group. The alkylene group having 2 or 3 carbon atoms may be linear or branched, and examples thereof include an ethylene group, a propylene group, and an isopropylene group, and an ethylene group or an isopropylene group is preferable. The p A ¹ Os may be the same or different, and the repeating unit in the case where they are different may be a block type or a random type, but from the viewpoint of molding temperature range and transparency, a block type is preferred, and polyoxypropylene- Polyoxyethylene-polyoxypropylene type and polyoxyethylene-polyoxypropylene-polyoxyethylene block types are preferred, and polyoxypropylene-polyoxyethylene-polyoxypropylene type block types are more preferred.

P in the formula (1) represents the average number of added moles of the oxyalkylene group, and 0 <p ≦ 300. From the viewpoint of molding temperature range and transparency, R ¹ is an alkyl group having 8 to 22 carbon atoms or In the case of an acyl group having 8 to 22 carbon atoms, 2 ≦ p ≦ 50 is preferable, and 5 ≦ p ≦ 20 is more preferable. When R ¹ is a hydrogen atom, 10 ≦ p ≦ 200 is preferable, and 20 ≦ p ≦ 100 is more preferable. Further, when both R ¹ and R ² are hydrogen atoms, 10 ≦ p ≦ 200 is preferable, and 20 ≦ p ≦ 100 is more preferable. Furthermore, when R ¹ is a hydrogen atom, it is preferable that (A ¹ O) _p contains different A ¹ O from the viewpoint of molding temperature range and transparency, and in particular, polyoxypropylene-polyoxyethylene- The block type of polyoxypropylene type and polyoxyethylene-polyoxypropylene-polyoxyethylene type are more preferable, and the block type of polyoxypropylene-polyoxyethylene-polyoxypropylene type is more preferable. The number (p ′) of constituting A ¹ O is preferably 5 ≦ p ′ ≦ 80, more preferably 5 ≦ p ′ ≦ 60. Further, in this case, the mass ratio (EO / PO) of polyoxyethylene (EO) to polyoxypropylene (PO) is preferably 5/95 to 70/30 from the viewpoint of molding temperature width and transparency. 95-60 / 40 is more preferred, 10 / 90-50 / 50 is more preferred, 10 / 90-40 / 60 is still more preferred, 10 / 90-30 / 70 is still more preferred, and 15 / 85-25 / 75 is more preferred. Further preferred.

The average molecular weight of the compound represented by the formula (1) is preferably 300 or more, more preferably 500 or more, from the viewpoint of improving fluidity at the time of melt kneading of the polylactic acid resin composition raw material and bleeding resistance at the time of molding. Preferably, it is 100,000 or less, More preferably, it is 50000 or less, More preferably, it is 10,000 or less, More preferably, it is 6000 or less. Moreover, from the viewpoint of heat resistance of the amorphous or semi-crystalline sheet made of the polylactic acid resin composition, it is preferably 1000 or more, more preferably 2000 or more, and preferably 6000 or less. In the present specification, the average molecular weight of the nonionic surfactant can be determined according to a general measurement method such as GPC.

Specific examples of the compound represented by the formula (1) include, for example, mono- or dietherified products of aliphatic alcohols having 8 to 22 carbon atoms and polyoxyethylene glycol or polyoxypropylene glycol, or those having 8 to 22 carbon atoms. And mono- or diesterified products of the fatty acids of polyoxyethylene glycol or polyoxypropylene glycol, and the methyl ethers of monoesterified products of fatty acids of 8 to 22 carbon atoms with polyoxyethylene glycol or polyoxypropylene glycol. From the viewpoint of transparency, fatty acid polyoxyethylene glycol ester or ester of fatty acid and methyl polyglycol is preferable, and ester of long chain fatty acid such as oleic acid and polyglycol is more preferable.

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 preferred 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.

The content of the nonionic surfactant is preferably 0.2 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin from the viewpoint of transparency of the thermoforming sheet and shortening of the semicrystallization time. 3 parts by mass or more is more preferable, 0.7 parts by mass or more is more preferable, 0.9 parts by mass or more is more preferable, from the viewpoint of thermoformability after storage at high temperature of the thermoforming sheet, and glass transition temperature improvement. 3.0 parts by mass or less, preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, further preferably 1.0 parts by mass or less, and even more preferably 0.8 parts by mass or less. .

In the present invention, other known surfactants 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 this surfactant, 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.

[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 monocarbodiimide compounds and polycarbodiimide compounds. 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 compound 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′-dicyclohexylmethanecarbodiimide) is obtained by converting carbodilite LA-1 (manufactured by Nisshinbo Chemical Co., Ltd.), poly (1,3,5-triisopropylbenzene) polycarbodiimide and poly (1,3,5-trimethyl). (Isopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide is stavaxol P and stabaxol P-100 (manufactured by Rhein Chemie), 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, and 1 part by weight or less is more preferable.

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 composed of a polylactic acid resin composition containing a polylactic acid resin, a specific amount of plasticizer, and a specific amount of organic crystal nucleating agent. If it contains the said component, it can prepare without particular limitation. For example, a raw material containing a polylactic acid resin, a specific amount of plasticizer, a specific amount of organic crystal nucleating agent, and various additives as required, is sealed kneader, single-screw or twin-screw extruder, open roll type kneading It can be prepared by melt-kneading using a known kneader such as a 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.

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. When filling the extruder, the raw materials constituting the polylactic acid resin composition, for example, the raw materials containing polylactic acid resin, plasticizer, organic crystal nucleating agent, and various additives as necessary are filled as they are. The mixture may be melt-kneaded or may be pre-melted and kneaded 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 further 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 is lowered from 200 ° C. to 20 ° C. at a temperature drop rate of −20 ° C./min, held at 20 ° C. for 1 minute, and further raised as 2ndRUN from 20 ° C. to 200 ° C. at a temperature rising rate of 20 ° C./min. 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 longer, more preferably 0.5 seconds or longer, further preferably 0.8 seconds or longer, preferably 50 seconds or shorter, more preferably 10 seconds or shorter, still more preferably 5 seconds. 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, further 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 uniform mixing and molecular weight suppression, the polylactic acid resin composition preferably has a cylinder temperature of 180 ° C or higher, preferably Can be filled into a mold having a desired shape using an injection molding machine set at 220 ° C. or lower, more preferably 210 ° C. or lower, and molded into a sheet.

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. Obtainable.

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

In addition, immediately after pressing under the above conditions, preferably 0 to 40 ° C., 0.1 to 20 MPa, more preferably 10 to 30 ° C., 0.1 to 10 MPa, further preferably 10 to 20 ° C. It is preferable to cool by pressing under conditions of 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. Although the crystallinity of the thermoforming sheet of the present invention is not particularly limited, it is preferable that the sheet is in an amorphous state or a semicrystalline state by cooling during the forming. The thermoforming sheet of the present invention obtained by cooling has a relative crystallinity calculated by the above formula of preferably less than 80%, more preferably less than 60%, and even more preferably less than 50%. The lower limit is not particularly set, but may be 0% or more.

The thickness of the thermoforming sheet of the present invention 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 further preferably 1.2 mm. It is as follows.

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, and 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, further preferably 10 seconds or more, preferably 27 seconds or less, more preferably from the viewpoint of moldability. Is 25 seconds or less, more preferably 24 seconds or less. In the present specification, the half crystallization time can be determined according to the method described in Examples described later.

The present invention also provides a method for producing the thermoforming sheet of the present 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 temperature-adjusted air (air knife), temperature adjustment tank using infrared rays or a 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.

Below, the suitable aspect of the manufacturing method of the sheet | seat for thermoforming of this invention is given. That is, the manufacturing method of the sheet | seat for thermoforming including the following process (A) and (B) is mentioned. In addition, the preset temperature of an extruder and the preset temperature of a cooling roll are as above-mentioned.
Step (A): The polylactic acid resin contains 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Step (B) for preparing a sheet molded product by extruding the polylactic acid resin composition to be extruded by an extruder having a temperature of 170 to 240 ° C .: Cooling the sheet molded product obtained in the step (A) at a temperature of less than 40 ° C. The process of cooling by contacting the roll

In step (A), the polylactic acid resin composition in the present invention is extruded by an extruder to prepare a sheet molded product. The components and content of the polylactic acid resin composition are the same as described above. The set temperature of the extruder is preferably 170 ° C. or higher, preferably 240 ° C. or lower, more preferably 220 ° C. or lower. Other extrusion conditions are as described above.

In step (B), the sheet molded product obtained in step (A) is brought into contact with a cooling roll and cooled. By doing in this way, the amorphous | non-crystalline state or semi-crystalline state can be favorably maintained for the thermoforming sheet obtained. The set temperature of the cooling roll is preferably less than 40 ° C, more preferably 30 ° C or less, and further preferably 20 ° C or less. Other cooling 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 article 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 such as vacuum forming or pressure forming.

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): The polylactic acid resin contains 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Step (2) for heating a thermoforming sheet comprising a polylactic acid resin composition 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 (1) Thermoforming the sheet obtained in step 1 using a mold having a mold temperature of 60 to 140 ° C.

The thermoforming sheet used in step (1) is the thermoforming sheet of the present invention, and the constituents 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, further preferably 65 ° C. or higher, preferably 120 ° C. or lower, more preferably 100 ° C. or lower, and further 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. The holding time in the mold is preferably 2 to 60 seconds in a mold at 90 ° C., for example, from the viewpoint of improving the heat resistance and productivity of the thermoformed article made of the polylactic acid resin composition, and 3 to 30 seconds. Is more preferable, and 5 to 20 seconds is more preferable. In a mold at 100 ° C., 2 to 60 seconds is preferable, 3 to 30 seconds is more preferable, 5 to 20 seconds is more preferable, and 5 to 15 seconds is still more preferable. . 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 to 30 ° C.

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.

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

The relative crystallinity of the thermoformed product of the present invention is preferably 80% or more, more preferably 90% or more. 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 forming the sheet by vacuum forming or pressure forming.

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.

In relation to the above-described embodiment, the present invention further discloses the following thermoforming sheet and method for producing the same, as well as a molded article formed by molding the sheet, a method for producing the same, and a method for processing the sheet.
<1> A polylactic acid resin containing 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. A thermoforming sheet comprising a lactic acid resin composition.

<2> The content of the polylactic acid resin in the polylactic acid resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more, for thermoforming as described in <1>. Sheet.
<3> The plasticizer is preferably a compound having two or more ester groups in the molecule, preferably having two or more ester groups in the molecule and an average added mole number of ethylene oxide per molecule. The thermoforming sheet according to <1> or <2>, wherein a compound of 2 to 9, more preferably 3 to 9, is more preferable.
<4> Plasticizers include esters of polycarboxylic acids and monoalcohols or their (poly) oxyalkylene adducts, and monovalent carboxylic acids or polycarboxylic acids and polyhydric alcohols or (poly) oxyalkylenes thereof. The thermoforming sheet according to any one of <1> to <3>, wherein an ester with an adduct is preferable.
<5> The plasticizer is preferably an ester of acetic acid and glycerin in average 3 to 6 moles of ethylene oxide adduct (1 to 2 moles of ethylene oxide added per hydroxyl group), average number of moles of acetic acid and ethylene oxide added Is an ester with polyethylene glycol of 4 to 6, an ester of polyethylene glycol monomethyl ether with an average addition mole number of succinic acid and ethylene oxide of 2 to 3 (addition of 2 to 3 mol of ethylene oxide per hydroxyl group), adipic acid And esters of diethylene glycol monomethyl ether, adipic acid and 1-butyl alcohol, acetyl citric acid and 1-butyl alcohol, 1,3,6-hexanetricarboxylic acid and diethylene glycol monomethyl ether From One or more selected, 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, ester of acetylcitric acid and 1-butyl alcohol The sheet for thermoforming according to any one of <1> to <4>, wherein one or more selected from the group consisting of:
<6> The content of the plasticizer is preferably 1 part by mass or more, more preferably 1.2 parts by mass or more, preferably 3 parts by mass or less, and 2.5 parts by mass or less with respect to 100 parts by mass of the polylactic acid resin. The sheet for thermoforming according to any one of <1> to <5>, which is more preferable.
<7> The organic crystal nucleating agent is preferably an aliphatic compound having a total of two or more of one or more groups selected from the group consisting of ester groups, hydroxyl groups, and amide groups in the molecule. An aliphatic compound having one or more and one or more ester groups or amide groups is more preferable, and an aliphatic compound having two or more hydroxyl groups and one or more ester groups or amide groups is further provided. The thermoforming sheet according to any one of the above items <1> to <6>, preferably an aliphatic compound having two or more hydroxyl groups and two or more ester groups or amide groups.
<8> As the organic crystal nucleating agent, hydroxy fatty acid monoamide and hydroxy fatty acid bisamide are preferable, 12-hydroxy stearic acid monoethanolamide, methylene bis 12-hydroxy stearic acid amide, ethylene bis 12-hydroxy stearic acid amide, hexamethylene bis 12 The thermoforming sheet according to any one of <1> to <7>, wherein hydroxystearic acid amide is more preferable.
<9> The content of the organic crystal nucleating agent is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and still more preferably 0.33 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin. The sheet for thermoforming according to any one of <1> to <8>, preferably 0.4 parts by mass or less, and more preferably 0.38 parts by mass or less.
<10> The polylactic acid resin composition constituting the thermoforming sheet preferably further contains a nonionic surfactant represented by the following formula (1), any of the above <1> to <9> The sheet for thermoforming as described.
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, or a hydrogen atom, and R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a total carbon atom. An acyl group having a number of 2 to 4, A ¹ represents an alkylene group having 2 or 3 carbon atoms, p represents an average number of moles added of the oxyalkylene group, and 0 <p ≦ 300, The p oxyalkylene groups represented by A ¹ O) may be the same or different, and the repeating unit in different cases may be either a block type or a random type.
When ^{R 1} is a hydrogen atom in the <11> formula (1) may, ^{R 2} also is preferably a hydrogen atom, a <10> thermoforming sheet according.
<12> The p A ¹ O in the formula (1) is preferably a block type, preferably a polyoxypropylene-polyoxyethylene-polyoxypropylene type or a polyoxyethylene-polyoxypropylene-polyoxyethylene type block type. The block type of polyoxypropylene-polyoxyethylene-polyoxypropylene type is more preferable, and the number (p ′) of A ¹ O constituting each block unit in that case is preferably 5 ≦ p ′ ≦ 80, 5 ≦ p ′ ≦ 60 is more preferable, and the mass ratio (EO / PO) of polyoxyethylene (EO) to polyoxypropylene (PO) is preferably 5/95 to 70/30, and 5/95 to 60/40. Is more preferable, 10/90 to 50/50 is more preferable, 10/90 to 40/60 is further preferable, and 10/9 is preferable. ~ More preferably 30/70, more preferably 15/85 ~ 24/75, the <10> or <11> thermoforming sheet according.
<13> The average molecular weight of the compound represented by the formula (1) is preferably 300 or more, more preferably 500 or more, preferably 100,000 or less, more preferably 50,000 or less, still more preferably 10,000 or less, and still more preferably. The thermoforming sheet according to any one of <10> to <12>, which is 6000 or less, preferably 1000 or more, more preferably 2000 or more, and preferably 6000 or less.
<14> The content of the nonionic surfactant is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and 0.7 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin. More preferably, 0.9 parts by mass or more is more preferable, 3.0 parts by mass or less is preferable, 2.0 parts by mass or less is more preferable, 1.5 parts by mass or less is further preferable, and 1.0 part by mass or less is further more preferable. The thermoforming sheet according to any one of <10> to <13>, preferably 0.8 parts by mass or less.
<15> The thermoforming sheet according to any one of <1> to <14>, wherein the polylactic acid resin composition constituting the thermoforming sheet may further include a carbodiimide compound as a hydrolysis inhibitor. .
<16> The content of the hydrolysis inhibitor is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably 0.15 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin. The thermoforming sheet according to <15>, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 1 part by mass or less.
<17> A raw material containing 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. <1> to <16, comprising a polylactic acid resin composition obtained by melt-kneading using a kneading machine using a known kneader such as a closed kneader, a single- or twin-screw extruder, or an open roll kneader. > The thermoforming sheet according to any one of the above.
<18> 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 not less than Tm ° C and not more than Tm + 50 ° C. Specifically, the thermoforming sheet according to <17>, which is preferably 170 ° C. or higher, preferably 240 ° C. or lower, more preferably 220 ° C. or lower.
<19> The thermoforming sheet according to any one of <1> to <18>, which can be prepared by extrusion molding, injection molding, or press molding the polylactic acid resin composition.
<20> The thermoforming sheet according to any one of <1> to <19>, which is an amorphous or semi-crystalline sheet.
<21> 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 even more preferably 1.2 mm. The thermoforming sheet according to any one of the above items <1> to <20>, which is as follows.
<22> The glass transition temperature of the thermoforming sheet is preferably 50 ° C. or higher, more preferably 51 ° C. or higher, still more preferably 52 ° C. or higher, preferably 60 ° C. or lower, more preferably 59 ° C. or lower, still more preferably. The thermoforming sheet according to any one of <1> to <21>, wherein is a temperature of 58 ° C. or lower.
<23> The half crystallization time of the thermoforming sheet is preferably 5 seconds or more, more preferably 8 seconds or more, further preferably 10 seconds or more, preferably 27 seconds or less, more preferably 25 seconds or less, The thermoforming sheet according to any one of <1> to <22>, wherein the sheet is preferably 24 seconds or shorter.
<24> A method for producing a thermoforming sheet comprising the following steps (A) and (B).
Step (A): The polylactic acid resin contains 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Step (B) for preparing a sheet molded product by extruding the polylactic acid resin composition to be extruded by an extruder having a temperature of 170 to 240 ° C .: Cooling the sheet molded product obtained in the step (A) at a temperature of less than 40 ° C. Step <25> for contacting with roll and cooling <25> The set temperature of the extruder in step (A) is preferably 170 ° C. or higher, preferably 240 ° C. or lower, more preferably 220 ° C. or lower, <24 > The manufacturing method of the sheet | seat for thermoforming of description.
<26> The temperature for setting the cooling roll in the step (B) is preferably less than 40 ° C, more preferably 30 ° C or less, and further preferably 20 ° C or less, and the production of the thermoforming sheet according to <24> or <25>. Method.
<27> As a packaging material for daily necessities, cosmetics, home appliances, etc., it can be thermoformed into blister packs and trays, food containers such as lunch box lids, industrial trays used for transportation and protection of industrial parts, etc. <1> to <23> The thermoforming sheet according to any one of the above.
<28> A thermoformed article obtained by vacuum forming or pressure forming the thermoforming sheet of any one of <1> to <23>.
<29> A method for producing a thermoformed article comprising the following steps (1) and (2).
Step (1): The polylactic acid resin contains 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Step (2) for heating a thermoforming sheet comprising a polylactic acid resin composition 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 (1) Step <30> for thermoforming the sheet obtained in step 1 using a mold having a mold temperature of 60 to 140 ° C. The heating temperature of the thermoforming sheet in step (1) is preferably 50 ° C. or more, more preferably 60 The method for producing a thermoformed article according to the above <29>, wherein the method is at least ° C, more preferably at least 65 ° C, preferably at most 120 ° C, more preferably at most 100 ° C, further preferably at most 90 ° C.
<31> The mold temperature in the step (2) is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, further preferably 80 ° C. or higher, preferably 120 ° C. or lower, more preferably 115 ° C. or lower, The method for producing a thermoformed article according to <29> or <30>, which is preferably 110 ° C. or lower.
<32> The thickness of the thermoformed body is preferably 0.1 mm or more, more preferably 0.15 mm or more, further preferably 0.2 mm or more, preferably 1.5 mm or less, more preferably 1.4 mm or less, More preferably, the thermoformed body according to the above <28>, which is 1.2 mm or less.
<33> The haze value of the thermoformed article is preferably 0.1% or more, more preferably 0.2% or more, still more preferably 0.3% or more, preferably 8.0% or less, more preferably The thermoformed article according to the above <28> or <32>, which is 7.0% or less, more preferably 6.5% or less.
<34> The thermoformed article according to any one of <28>, <32>, and <33>, wherein the relative crystallinity of the thermoformed article is preferably 80% or more, more preferably 90% or more.
<35> A secondary processing method for a thermoforming sheet, comprising vacuum forming or pressure forming the thermoforming sheet of any one of <1> to <23>.
<36> As packaging materials for daily necessities, cosmetics, home appliances, etc., it can be suitably used for blister packs and trays, food containers such as lunch box lids, industrial trays used for transportation and protection of industrial parts, <28>,<32>,<33>,<34>.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples. 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., and the pressure was gradually reduced from normal pressure to 6.7 kPa over 1.5 hours to distill off methanol, and then 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 to 15 and Comparative Examples 1 to 6
Preparation of Polylactic Acid Resin Composition As a polylactic acid resin composition, the composition raw materials shown in Tables 1 to 3 were used for 10 minutes at a rotational speed of 90 r / min with a twin screw extruder “HK-25D” (manufactured by PARKER). Then, melt kneading was performed at a melt kneading temperature of 180 to 190 ° C., and strand cutting was performed to obtain pellets of a polylactic acid resin composition. 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).

Next, the thermoforming sheet was attached to a guide using a single vacuum / pressure forming machine “FVS-500P WAKITEC” (manufactured by Wakisaka Manufacturing 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 properties of the obtained thermoforming sheet and thermoformed product were evaluated according to Test Examples 1 to 5 below. Moreover, about the obtained sheet | seat for thermoforming, after winding with the force of 2 kg around the paper core (The product made from Oka packaging material, internal diameter 76.2mm, thickness 10mm, length 300mm), various temperature (33 degreeC, 35 degreeC, A thermoformed body was prepared according to the above molding method and evaluated in the same manner as described above, after placing in a constant temperature and humidity machine (LHL-113, manufactured by ESPEC) set at 38 ° C. for 24 hours. The results are shown in Tables 1 to 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. If it is 3 or more by evaluation criteria, it is preferable that it is 4 or more.
Shape: By a well-trained evaluator, 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.
Fitability: Fits to the main body part (φ81mm, height 51mm, material made of low foamed PS with PP) of a commercially available container (trade name Yumomi 90 Shino C-Peisei Co., Ltd.) and below by a well-trained evaluator Evaluation was performed according to the evaluation criteria.
〔Evaluation criteria〕
4: It is the same shape as a molded object standard, and it 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 is almost the same shape as the molded product, and can be barely fitted.
1: The shape is clearly different from the molded article 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 holding 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. If the relative crystallinity is less than 80%, it is in an amorphous state, and if 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.

The raw materials in Tables 1 to 3 are 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 DAIFACTY-101 produced in Production Example 1 for the plasticizer: Diester of adipic acid and diethylene glycol monomethyl ether / benzyl alcohol = 1/1 mixture, ATBC manufactured by Daihachi Chemical Industry Co., Ltd .: Acetyltributylcitric acid, manufactured by Taoka Chemical Co., Ltd. [Organic crystal nucleating agent]
SLIPAX H: Ethylene bis 12-hydroxystearic acid amide, Nippon Kasei Co., Ltd. SLIPAX O: Ethylene bis oleic acid amide, Nippon Kasei Co., Ltd. [nonionic surfactant]
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 A compound having a polyoxyethylene-polyoxypropylene block type, wherein the polyoxypropylene group has a p 'of 47, the polyoxyethylene group has a p' of 16, and the total p in formula (1) is 63 [hydrolysis Inhibitor]
Carbodilite LA-1: Aliphatic polycarbodiimide compound, manufactured by Nisshinbo Chemical Co., Ltd.

From the results shown in 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 product exhibits high crystallinity and good transparency. And had a good appearance.

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 household appliances, and trays for industrial parts.

Claims (14)

A polylactic acid resin composition containing 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Thermoforming sheet made of material. The thermoforming sheet according to claim 1, wherein the glass transition temperature of the thermoforming sheet is 50 to 60 ° C. 3. The thermoforming sheet according to claim 1, wherein the thermoforming sheet has a half-crystallization time of 5 to 27 seconds, and the resulting thermoformed article has a Haze value of 0.1 to 8.0%. The organic crystal nucleating agent includes an aliphatic compound having a total of two or more of one or more groups selected from the group consisting of an ester group, a hydroxyl group, and an amide group in the molecule. The sheet for thermoforming as described in 1. The thermoforming sheet according to any one of claims 1 to 4, 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 5, wherein the polylactic acid resin composition further contains a nonionic surfactant 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, or a hydrogen atom, and R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a total carbon atom. An acyl group having a number of 2 to 4, A ¹ represents an alkylene group having 2 or 3 carbon atoms, p represents an average number of moles added of the oxyalkylene group, and 0 <p ≦ 300, The p oxyalkylene groups represented by A ¹ O) may be the same or different, and the repeating unit in different cases may be either a block type or a random type. The thermoforming sheet according to any one of claims 1 to 6, wherein the thermoforming sheet is an amorphous or semi-crystalline sheet. The manufacturing method of the sheet | seat for thermoforming including the following process (A) and (B).
Step (A): The polylactic acid resin contains 0.5 to 3.5 parts by mass of a plasticizer and 0.15 to 0.45 parts by mass of an organic crystal nucleating agent with respect to 100 parts by mass of the polylactic acid resin. Step (B) for preparing a sheet molded product by extruding the polylactic acid resin composition to be extruded by an extruder having a temperature of 170 to 240 ° C .: Cooling the sheet molded product obtained in the step (A) at a temperature of less than 40 ° C. The process of cooling by contacting the roll 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 7 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 to 140 ° C. The manufacturing method according to claim 9, wherein the relative crystallinity of the thermoformed product is 80% or more. A molded body formed by vacuum forming or pressure forming the thermoforming sheet according to any one of claims 1 to 7. A sheet secondary processing method, characterized by vacuum forming or pressure forming the thermoforming sheet according to any one of claims 1 to 7. A packaging material comprising the molded article according to claim 11. A thermoforming sheet having a glass transition temperature of 50 to 60 ° C., a half crystallization time of 5 to 27 seconds, and a Haze value of the obtained thermoformed article of 0.1 to 8.0%.

Images