JP2016113539A - Polylactic acid resin composition - Google Patents

Abstract

The present invention relates to a polylactic acid resin composition having both impact resistance and transparency, a sheet-like molded article comprising the polylactic acid resin composition, and a method for producing the sheet-like molded article. A polylactic acid resin composition comprising (A) a polylactic acid resin, (B) a plasticizer, and (C) a fatty acid alkanolamide, wherein two (B) plasticizers are present in the molecule. An ester compound having an ester group as described above, wherein at least one of the alcohol components constituting the ester compound is an average of 0.5 to 8 moles of an alkylene oxide having 2 or 3 carbon atoms per hydroxyl group. A polylactic acid resin composition comprising one or more selected from the group consisting of an ester compound represented by formula (I) and an ester compound represented by the following formula (I): R1O-CO-R2-CO-[(OR3) mO-CO-R2-CO-] nOR1 (I) [Selection] None

Description

  The present invention relates to a polylactic acid resin composition. More specifically, a polylactic acid resin composition that can be suitably molded into a molded article such as a clear case or tray for daily necessities, cosmetics, home appliances, etc., a sheet-like molded article comprising the polylactic acid resin composition, and the sheet-like molding The present invention relates to a method for manufacturing a body.

  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, Patent Document 1 discloses an aliphatic polyester resin composition characterized by containing (A) an aliphatic polyester and (B) a multilayer structure polymer as an aliphatic polyester resin composition having excellent impact resistance. Disclosure. As the (A) aliphatic polyester, polylactic acid is exemplified, and as the (B) multilayer structure polymer, it is described that a multilayer structure polymer having at least one rubber layer therein is preferable. In such a composition, it is disclosed that a plasticizer is blended for the purpose of improving heat resistance. Specifically, for example, in Example 7, 100 parts by weight of a polylactic acid resin and a core-shell type rubber-based weight are disclosed. A composition containing 23 parts by weight of a coalescence, 26 parts by weight of an inorganic crystal nucleating agent, and 3 parts by weight of a polyethylene glycol / polypropylene glycol copolymer as a plasticizer is disclosed.

JP 2003-286396 A

  However, when trying to improve impact resistance using a conventionally used rubber-based impact modifier, for example, it is necessary to blend in a large amount as described in Patent Document 1, and the resulting molding Decrease in body transparency becomes a problem.

  The present invention relates to a polylactic acid resin composition having both impact resistance and transparency, a sheet-like molded article comprising the polylactic acid resin composition, and a method for producing the sheet-like molded article.

  As a result of intensive studies by the present inventors, a combination of a specific plasticizer and a fatty acid alkanolamide with a polylactic acid resin improves the impact resistance and further provides a polylactic acid resin composition having excellent transparency. As a result, the present invention has been completed.

That is, the present invention relates to the following [1] to [3].
[1] A polylactic acid resin composition comprising (A) a polylactic acid resin, (B) a plasticizer, and (C) a fatty acid alkanolamide,
The (B) plasticizer is an ester compound having two or more ester groups in the molecule, and at least one of the alcohol components constituting the ester compound is an alkylene oxide having 2 or 3 carbon atoms per hydroxyl group. A polylactic acid resin composition comprising one or more selected from the group consisting of an ester compound which is an alcohol added with an average of 0.5 mol or more and 8 mol or less and an ester compound represented by the following formula (I).
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 or 3 carbon atoms, and m is 1 A number of 6 or less and n represents a number of 1 to 12 inclusive, provided that all R ² may be the same or different, and all R ³ may be the same or different.
[2] A sheet-like molded article containing the polylactic acid resin composition according to [1], having a relative crystallinity of 80% or more.
[3] The method for producing a sheet-like molded body according to [1], including the following steps (1) and (2).
Step (1): A step of preparing a polylactic acid resin composition by melting and kneading a raw material containing (A) a polylactic acid resin, (B) a plasticizer, and (C) a fatty acid alkanolamide, ) The plasticizer is an ester compound having two or more ester groups in the molecule, and at least one alcohol component constituting the ester compound is an average of 0 or 2 alkylene oxides having 2 or 3 carbon atoms per hydroxyl group. A process comprising one or more selected from the group consisting of an ester compound which is an alcohol added with 5 mol or more and 8 mol or less and an ester compound represented by the following formula (I): R ¹ O—CO—R ² —CO - _{^{[(OR 3) m O-CO}} -R 2 -CO- ] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 or 3 carbon atoms, and m is 1 A number of 6 or less and n represents a number of 1 to 12 inclusive, provided that all R ² may be the same or different, and all R ³ may be the same or different.
Step (2): Step of extruding the polylactic acid resin composition obtained in Step (1)

  The polylactic acid resin composition of the present invention has an excellent effect that both impact resistance and transparency can be achieved.

  The polylactic acid resin composition of the present invention contains (A) a polylactic acid resin, (B) a specific plasticizer, and (C) a fatty acid alkanolamide.

  Fatty acid alkanolamides are nonionic surfactants composed of fatty acids and alkanolamines, and are conventionally used as antistatic agents, foaming agents, and thickeners. The antistatic agent is known as an optional component of the polylactic acid resin composition, as described in Patent Document 1, for example. In the present invention, by combining a specific plasticizer with the fatty acid alkanolamide, the reason is not clear, but the aliphatic alkanolamide is finely contained in the resin composition by a specific plasticizer that is compatible with the polylactic acid resin. It is presumed that by dispersing and dispersing stress when an impact is applied, the impact resistance and transparency are excellent. However, these assumptions do not limit the present invention.

[Polylactic acid resin composition]
[(A) Polylactic acid resin]
Examples of the polylactic acid resin include commercially available polylactic acid resins such as those manufactured by Nature Works: Nature Works PLA / 3001D, 4032D, 2500HP, and 3100HP, as well as polylactic acid resins synthesized from lactic acid and lactide. From the viewpoint of strength and transparency, a polylactic acid resin having an optical purity of 90% or more is preferable. For example, a polylactic acid resin (4032D, 2500HP, etc.) manufactured by Nature Works with a relatively high molecular weight and high optical purity is preferable.

  In the present invention, from the viewpoint of the strength and transparency of the polylactic acid resin composition, as the polylactic acid resin, a stereocomplex comprising two types of polylactic acid obtained by using lactic acid components mainly composed of different isomers. Polylactic acid resin may be used.

  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”.

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

[(B) Plasticizer]
As the plasticizer, one or more ester compounds selected from the group consisting of the following (i) and (ii) are used.
(i) An ester compound having two or more ester groups in the molecule, wherein at least one of the alcohol components constituting the ester compound is an average of 0.5 or 2 alkylene oxides per hydroxyl group Ester compound which is an alcohol added with 8 mol or less
(ii) An ester compound represented by the following formula (I): R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 or 3 carbon atoms, and m is 1 A number of 6 or less and n represents a number of 1 to 12 inclusive, provided that all R ² may be the same or different, and all R ³ may be the same or different.

  The ester compound (i) is an ester having 2 or more, preferably 2 or more and 5 or less, more preferably 2 or more and 3 or less ester groups in the molecule from the viewpoint of impact resistance and transparency. A compound in which at least one of the alcohol components constituting the ester compound is an average of 0.5 to 8 mol, preferably 1 to 6 mol, of an alkylene oxide having 2 or 3 carbon atoms per hydroxyl group, More preferably, it contains an ester compound which is an alcohol added in an amount of 1 mol or more and 3 mol or less, preferably 2 or more, preferably 2 or more and 5 or less, more preferably 2 or more and 3 or less esters in the molecule. A polyhydric alcohol ester or polycarboxylic acid ester having a group, wherein at least one of the alcohol components constituting the ester compound has one hydroxyl group The alkylene oxide having 2 or 3 carbon atoms average 0.5 mol or more 8 mole or, preferably 1 mol or more 6 mol or less, more preferably containing an ester compound is an alcohol obtained by adding 1 mol or more 3 mol.

  Specifically, for example, plasticizers described in JP 2008-174718 A and JP 2008-115372 A can be given. Of these, an average of 3 to 6 moles of an adduct of acetic acid and glycerin with an average of 3 to 6 moles of 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 to 4 Esters with 6 or less polyethylene glycol, esters with succinic acid and ethylene oxide having an average addition mole number of 2 to 3 polyethylene glycol monomethyl ether (addition of 2 to 3 mol of ethylene oxide per hydroxyl group), adipine An ester of an acid and diethylene glycol monomethyl ether and an ester of 1,3,6-hexanetricarboxylic acid and diethylene glycol monomethyl ether are preferably used.

  The ester compound (ii) is preferable from the viewpoint of impact resistance, transparency, and bleed resistance.

R ¹ in the formula (I) represents an alkyl group having 1 to 4 carbon atoms, more preferably 1 or 2, and two are present in one molecule and are present at both ends of the molecule. R ¹ may be linear or branched as long as it has 1 to 4 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group and a tert-butyl group. A methyl group is preferable from the viewpoint of suppressing the out and from the viewpoint of impact resistance and transparency.

R ² in the formula (I) represents an alkylene group having 2 to 4 carbon atoms, and a linear alkylene group is a preferred example. Specific examples include an ethylene group, a 1,3-propylene group, and a 1,4-butylene group. Among them, the viewpoint of improving the compatibility with the polylactic acid resin and suppressing the bleed-out of the plasticizer, and the resistance to resistance. From the viewpoint of impact and transparency, an ethylene group and a 1,3-propylene group are preferable, and an ethylene group is more preferable. However, all R ² may be the same or different.

R ³ in formula (I) represents an alkylene group having 2 or 3 carbon atoms, and OR ³ represents an oxyalkylene group. Specific examples include an ethylene group, a 1,2-propylene group, and a 1,3-propylene group. However, all R ³ may be the same or different.

  m represents the average number of repeating oxyalkylene groups and is a number of 1 or more and 6 or less. When m increases, the ether group value of the ester compound represented by the formula (I) increases, which tends to be oxidized and the stability tends to decrease. From the viewpoint of improving the compatibility with the polylactic acid resin, the number is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and still more preferably 1 or more and 2 or less.

  n represents an average degree of polymerization and is a number of 1 or more and 12 or less. From the viewpoint of improving the compatibility with the polylactic acid resin and suppressing the bleeding out of the plasticizer, and from the viewpoint of impact resistance and transparency, the number of 1 or more and 4 or less is preferable, and the number of 1 or more and 3 or less is more preferable. A number of 1 or more and 2 or less is more preferable.

  Among such structures, from the viewpoint of improving volatility resistance, at least one dibasic acid selected from succinic acid, glutaric acid, and adipic acid, diethylene glycol, triethylene glycol, 1,2-propanediol, and 1 At least one dihydric alcohol oligoester selected from 1,3-propandiol (in formula (I), n = 1 to 3) is preferred.

  The compound represented by the formula (I) may be a commercially available product or may be synthesized according to a known production method, for example, produced according to a method disclosed in JP2012-62467A. be able to.

  In the present invention, plasticizers other than the above (i) and (ii) can be used within a range not impairing the effects of the present invention. Examples of the other plasticizers include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, polyalkylene glycol plasticizers, and epoxy plasticizers other than the above (i) and (ii). An agent or the like can be used. The content of one or more ester compounds selected from the group consisting of (i) and (ii) in the plasticizer is preferably 50% by mass or more from the viewpoint of impact resistance and transparency, and is 70% by mass. % Or more is more preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, and 100 mass% is still more preferable. In the present specification, the content of one or more ester compounds selected from the group consisting of (i) and (ii) means the total content when a plurality of compounds are used. .

  The content of the plasticizer is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin from the viewpoint of impact resistance and transparency. It is preferably 6 parts by mass or more, more preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 10 parts by mass or less, from the viewpoint of bleeding resistance and suppression of generation of eyes.

[(C) Fatty acid alkanolamide]
The fatty acid alkanolamide used in the present invention is an amide compound comprising a fatty acid and an alkanolamine, and can be obtained by condensation reaction of a fatty acid and an alkanolamine.

  Examples of the fatty acid include a saturated or unsaturated fatty acid having a linear or branched chain. The number of carbon atoms of the fatty acid is preferably 10 or more, more preferably 12 or more, preferably 22 or less, more preferably 18 or less, still more preferably 16 or less, and even more preferably, from the viewpoint of impact resistance and transparency. Is 14 or less. Specific examples include capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitooleic acid, stearic acid, isostearic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid, and 12-hydroxystearic acid. From the viewpoint of impact resistance and transparency, one or more selected from lauric acid, myristic acid, stearic acid, and oleic acid are preferred, and one selected from lauric acid, myristic acid, and stearic acid Or 2 or more types are more preferable, and a myristic acid is still more preferable from a viewpoint of impact resistance.

  As the alkanolamine, an alkanolamine having 1 to 3 alkanol groups having 2 to 4 carbon atoms can be used. Of these, the alkanol group is preferably a hydroxyethyl group from the viewpoint of impact resistance. Other than the alkanol group is a hydrogen atom, but it may be an alkyl group having 1 to 5 carbon atoms.

  As the alkanolamine, monoalkanolamine, dialkanolamine, and a mixture thereof (a mixture of monoalkanolamine and dialkanolamine) can be used. Examples of the monoalkanolamine include monoethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, and monoisopropanolamine. Examples of dialkanolamines include diethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, and diisopropanolamine. Among these, from the viewpoint of impact resistance and transparency, one or more selected from monoethanolamine, diethanolamine, monoisopropanolamine, and diisopropanolamine are preferable, and monoethanolamine, diethanolamine, and monoisopropanol are preferred. One or more selected from amines are more preferable, and from the viewpoint of impact resistance, one or two selected from monoethanolamine and monoisopropanolamine are more preferable, and monoethanolamine is even more preferable.

  The fatty acid alkanolamide in the present invention is selected from the group consisting of fatty acids having 10 to 22 carbon atoms, monoethanolamine, diethanolamine, monoisopropanolamine, and diisopropanolamine from the viewpoint of impact resistance and transparency. Condensation products with one or more are preferred, lauric acid monoethanolamide, lauric acid monoisopropanolamide, lauric acid diethanolamide, myristic acid monoethanolamide, myristic acid monoisopropanolamide, myristic acid diethanolamide, stearic acid Monoethanolamide, stearic acid diethanolamide, and oleic acid diethanolamide are more preferable. From the viewpoint of impact resistance, lauric acid monoethanolamide and lauric acid monoisopropa Ruamido, myristic acid diethanolamide is more preferable.

  The fatty acid alkanolamide in the present invention may be prepared by performing a condensation reaction according to known conditions, or a commercially available product may be used.

  From the viewpoint of impact resistance, the content of the fatty acid alkanolamide is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and 0.2 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin. Is more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, still more preferably 0.8 parts by mass or more, and from the viewpoint of transparency, 5 parts by mass or less is preferable, It is more preferably 3 parts by mass or less, still more preferably 2 parts by mass or less, still more preferably 1 part by mass or less, and even more preferably 0.8 parts by mass or less. In addition, when using a some compound, it means total content.

  The mass ratio of (B) plasticizer to (C) fatty acid alkanolamide (plasticizer / fatty acid alkanolamide) is preferably 1 to 50 from the viewpoint of impact resistance and transparency, and from the viewpoint of impact resistance, 5-30 are more preferable and 10-20 are still more preferable.

[Crystal nucleating agent]
In addition to the above components, a crystal nucleating agent can be further used in the polylactic acid resin composition of the present invention from the viewpoint of improving the crystallization rate.

  Examples of the crystal nucleating agent include inorganic crystal nucleating agents and organic crystal nucleating agents. Examples of inorganic crystal nucleating agents include natural or synthetic silicate compounds, titanium oxide, barium sulfate, tricalcium phosphate, calcium carbonate, sodium phosphate, kaolinite, halloysite, talc, smectite, vermulite, mica, etc. It is done. Examples of the organic crystal nucleating agent include carboxylic acid amides other than fatty acid alkanolamides and metal salts of phenylphosphonic acid. From the viewpoint of improving transparency, carboxylic acid amides other than fatty acid alkanolamides are preferable. Examples of carboxylic acid amides other than fatty acid alkanolamides include alkylene bis fatty acid amides and alkylene bis hydroxy fatty acid amides. Examples of the alkylene bis fatty acid amide include ethylene bis fatty acid amide, propylene bis fatty acid amide, and butylene bis fatty acid amide. Examples of the ethylene bis fatty acid amide include ethylene bis stearic acid amide and ethylene bis oleic acid amide. The alkylene bishydroxy fatty acid amide is preferably an alkylene bishydroxy stearic acid amide having an alkylene group having 1 to 6 carbon atoms, more preferably ethylene bis 12-hydroxy stearic acid amide.

  The content of the crystal nucleating agent is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, with respect to 100 parts by mass of the polylactic acid resin, from the viewpoint of improving transparency and crystallinity. , Preferably 1.0 parts by mass or less, more preferably 0.7 parts by mass or less.

[Hydrolysis inhibitor]
Moreover, from the viewpoint of improving impact resistance, a hydrolysis inhibitor can be further used in the polylactic acid resin composition of the present invention in addition to the above components.

  Examples of the hydrolysis inhibitor include carbodiimide compounds such as polycarbodiimide compounds and monocarbodiimide compounds. From the viewpoint of improving impact resistance, polycarbodiimide compounds are preferable. Further, from the viewpoint of further improving the impact resistance, monocarbodiimide and polycarbodiimide may be used in combination.

  As said carbodiimide compound, a well-known carbodiimide compound can be used, and you may use it individually or in combination of 2 or more types. Specifically, for example, 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-triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide are stabuxol P and stabaxol P-100 (manufactured by Rhein Chemie), N, N′-di-2,6-diisopropylphenylcarbodiimide is stabuxol I (manufactured by Rhein Chemie) can be purchased and used.

  The content of the hydrolysis inhibitor is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably from 100 parts by mass of the polylactic acid resin, from the viewpoint of improving impact resistance. It is 0.3 parts by mass or more, preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and still more preferably 1 part by mass or less.

  The polylactic acid resin composition of the present invention has antistatic agents other than the above as lubricants, fillers (inorganic fillers, organic fillers), flame retardants, antioxidants, ultraviolet absorbers, and fatty acid alkanolamides. An agent, an antifogging agent, a light stabilizer, a pigment, an antifungal agent, an antibacterial agent, a foaming agent, and the like can be contained as long as the effects of the present invention are not impaired. 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 polylactic acid resin composition of the present invention can be prepared without particular limitation as long as it contains the components (A) to (C). For example, the polylactic acid resin, the plasticizer, and the fatty acid alkanolamide, If necessary, raw materials containing various additives can be prepared by melt-kneading using a known kneader such as a closed kneader, a single or twin screw extruder, an open roll kneader. 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 preparing the polylactic acid resin composition, in order to promote the plasticity of the polylactic acid resin, it may be melt-mixed in the presence of a supercritical gas. After the melt-kneading, the melt-kneaded product may be dried according to a known method.

  The melt-kneading temperature is not less than the melting point (Tm) of the polylactic acid resin from the viewpoint of inhibiting decomposition and transparency, preferably in the range of 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. Range. Specifically, for example, it is preferably 170 ° C. or higher, preferably 220 ° C. or lower, more preferably 200 ° 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 130 ° C. or higher, more preferably 140 ° C. or higher, still more preferably 160 ° C. or higher, preferably 210 ° C. or lower, more preferably 200 ° C. or lower, from the viewpoint of productivity. Preferably, 190 ° C. or lower is more preferable, 180 ° C. or lower is even more preferable, and 170 ° C. or lower is even more preferable.

  The glass transition temperature (Tg) of the polylactic acid resin composition is preferably 20 ° C. or higher, more preferably 25 ° C. or higher, still more preferably 30 ° C. or higher, and even more preferably 35 ° C. or higher, from the viewpoint of productivity. 40 ° C. or higher is more preferable, 60 ° C. or lower is preferable, 55 ° C. or lower is more preferable, and 50 ° C. or lower is still more preferable.

[Sheet-like molded product]
Since the polylactic acid resin composition of the present invention thus obtained is excellent in secondary processability such as thermoformability, for example, after filling the polyester resin composition of the present invention into a heated extruder and melting it, A sheet-like molded body can be obtained by extrusion from a T die. Therefore, this invention also provides the sheet-like molded object which consists of a polylactic acid resin composition of this invention. Here, the sheet-like molded body of the present invention is prepared by immediately adjusting the crystallinity of the sheet by bringing the extruded sheet-like molded body into contact with a cooling roll and then a heating roll, and then cutting the sheet-like molded body. It can also be obtained. When filling the extruder, the raw materials constituting the polylactic acid resin composition of the present invention, such as polylactic acid resin, plasticizer, and fatty acid alkanolamide, and if necessary, various additives are melt-kneaded. Thereafter, it may be extruded.

  From the viewpoint of improving transparency, the temperature of the extruder is preferably 170 ° C. or higher, more preferably 175 ° C. or higher, further preferably 180 ° C. or higher, preferably 240 ° C. or lower, more preferably 220 ° C. or lower, still more preferably. Is 210 ° C. or lower. In addition, in this invention, the temperature of an extruder means the cylinder temperature of the biaxial kneading part of an 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 improving transparency and improving peelability from the cooling roll, specifically, less than 40 ° C, preferably 30 ° C or less. Is more preferable.

  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, it improves transparency and improves peelability from the cooling roll. From this point of view, it is preferably 1 second or longer, more preferably 3 seconds or longer, still more preferably 5 seconds or longer, preferably 60 seconds or shorter, more preferably 50 seconds or shorter, still more preferably 40 seconds or shorter.

  The surface temperature of the heating roll is preferably set to Tg or higher of the polylactic acid resin composition from the viewpoint of improving transparency and improving crystallinity. Specifically, 65 ° C or higher is preferable, and 70 ° C or higher is more preferable. Preferably, 80 ° C. or higher is more preferable, and 90 ° C. or lower is preferable. The total time of contact with the heating roll is preferably 5 seconds or more, more preferably 10 seconds or more, and further preferably 15 seconds or more. In addition, the surface temperature of a cooling roll and a heating roll means the temperature actually measured on the roll surface, and can be measured using a contact-type thermometer.

  Moreover, this invention provides the manufacturing method of the sheet-like molded object of this invention.

  The production method may be a method including a step of melt-kneading and extrusion-molding a polylactic acid resin, a plasticizer, and a fatty acid alkanolamide. For example, the following method is suitably used.

Specifically, the manufacturing method which has the following process (1)-(2) is mentioned.
Step (1): A step of preparing a polylactic acid resin composition by melting and kneading a raw material containing (A) a polylactic acid resin, (B) a plasticizer, and (C) a fatty acid alkanolamide, ) The plasticizer is an ester compound having two or more ester groups in the molecule, and at least one alcohol component constituting the ester compound is an average of 0 or 2 alkylene oxides having 2 or 3 carbon atoms per hydroxyl group. A process comprising one or more selected from the group consisting of an ester compound which is an alcohol added with 5 mol or more and 8 mol or less and an ester compound represented by the following formula (I): R ¹ O—CO—R ² —CO - _{^{[(OR 3) m O-CO}} -R 2 -CO- ] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 or 3 carbon atoms, and m is 1 A number of 6 or less and n represents a number of 1 to 12 inclusive, provided that all R ² may be the same or different, and all R ³ may be the same or different.
Step (2): Step of extruding the polylactic acid resin composition obtained in Step (1)

  In step (1), a raw material containing (A) a polylactic acid resin, (B) a plasticizer, (C) a fatty acid alkanolamide, and other additives as necessary, a sealed kneader, uniaxial or biaxial Using a known kneader such as an extruder or an open roll type kneader, preferably at 170 ° C. or higher, preferably 220 ° C. or lower, more preferably 200 ° C. or lower, and polylactic acid resin. A composition is prepared. The raw materials and the conditions of melt kneading are in accordance with the terms of the polylactic acid resin composition of the present invention.

  In step (2), the polylactic acid resin composition obtained in step (1) is extruded. As extrusion molding, it can shape | mold using a well-known extrusion molding machine. For example, when an extrusion sheet molding machine (500 mm T-die manufactured by Plastic Engineering Laboratory Co., Ltd.) equipped with a cooling roll and a heating roll is used, a sheet-like molded body with adjusted crystallinity can be obtained. In addition, although the raw material of the polylactic acid resin composition of this invention may be supplied to an extruder and melt-kneaded as it is, what was melt-kneaded previously may be filled into an extruder.

  The melt kneading temperature in the extruder is filled and kneaded with the polylactic acid resin composition at a temperature suitable for the above-described melt kneading. The residence time at this time 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 conditions for the extruder and the conditions for the subsequent contact with the cooling roll and the heating roll are in accordance with the terms for the polylactic acid resin composition of the present invention.

Thus, the sheet-like molded product of the present invention is obtained. The sheet-like molded body of the present invention has a thickness of preferably 100 μm or more, more preferably 150 μm or more, preferably 1000 μm or less, more preferably 600 μm or less. In addition, when it is brought into contact with a cooling roll and a heating roll in order after extrusion, the thickness is the same as described above, and the relative crystallinity is preferably 80% or more, more preferably 90% or more and high crystallinity. is there. In the present specification, the relative crystallinity can be determined by the following formula, and if the relative crystallinity is 80% or more, it means that the crystallinity is high.
Relative crystallinity (%) = {(ΔHm−ΔHcc) / ΔHm} × 100
Specifically, the relative crystallinity was raised from 25 ° C. to 200 ° C. at a rate of temperature increase of 15 ° C./min using a DSC apparatus (diamond DSC manufactured by PerkinElmer Co., Ltd.) at a rate of temperature increase of 15 ° C./min. After being held, the temperature was lowered from 200 ° C. to 25 ° C. at a temperature drop rate of −500 ° C./min, held at 25 ° C. for 1 minute, and further increased from 25 ° C. to 200 ° C. at a temperature rising rate of 15 ° 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 sheet-like molded product of the present invention thus obtained has good transparency and excellent heat resistance and impact resistance, so that it can be used as a packaging material for various uses such as daily necessities, cosmetics, and home appliances. It can be thermoformed into trays, food containers such as lunch box lids, industrial trays used for transportation and protection of industrial parts, and the like. Therefore, the present invention also provides a thermoformed body formed by molding the sheet-like formed body of the present invention.

  The thermoformed article of the present invention is not particularly limited as long as the sheet-like molded article 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, what formed by vacuum forming or pressure forming the sheet-like molded object of this invention is mentioned.

  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 and holding at 25 ° C. for 1 minute, the temperature is raised from 25 ° C. to 200 ° C. at a rate of 15 ° C./min (2ndRUN).

Production Example 1 of Plasticizer ((MeEO ₃ ) ₂ SA, 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. The obtained diester had a weight average molecular weight of 410, a viscosity (23 ° C.) of 27 mPa · s, an acid value of 0.2 mgKOH / g, a saponification value of 270 mgKOH / g, a hydroxyl value of 1 mgKOH / g or less, and a hue of APHA200. In addition, the usage-amount of the catalyst was 0.94 mol with respect to 100 mol of dicarboxylic acid ester. In addition, this plasticizer is an ester compound with the alcohol which added 3 mol of ethylene oxide per hydroxyl group.

Production Example 2 of Plasticizer ((MeEO ₄ ) ₂ SA, Diester Compound of Succinic Acid and Tetraethylene Glycol Monomethyl Ether)
A 3 L flask equipped with a stirrer, thermometer, and dehydration tube was charged with 500 g of succinic anhydride, 3124 g of tetraethylene glycol monomethyl ether, and 9.5 g of paratoluenesulfonic acid monohydroxide, and nitrogen (500 mL / min) was added to the space. While blowing, the reaction was carried out at 130 ° C. for 20 hours under reduced pressure (4 to 10.7 kPa). The acid value of the reaction solution was 1.6 (mgKOH / g). After adding 27 g of adsorbent KYOWARD 500SH (manufactured by Kyowa Chemical Industry Co., Ltd.) to the reaction solution, stirring and filtering at 80 ° C. and 2.7 kPa for 45 minutes, tetraethylene at a liquid temperature of 150 to 250 ° C. and a pressure of 0.003 kPa. After distilling off the glycol monomethyl ether and cooling to 80 ° C., the residue was filtered under reduced pressure to obtain a diester [(MeEO ₄ ) ₂ SA] of succinic acid and tetraethylene glycol monomethyl ether as a filtrate. The obtained diester had a weight average molecular weight of 499, a viscosity (23 ° C.) of 35 mPa · s, an acid value of 0.2 mgKOH / g, a saponification value of 225 mgKOH / g, a hydroxyl value of 1 mgKOH / g or less, and a hue of APHA230. In addition, this plasticizer is an ester compound with the alcohol which added 4 mol of ethylene oxide per hydroxyl group.

Production Example 3 of Plasticizer ((MeEO ₆ ) ₂ SA, Diester Compound of Succinic Acid and Hexaethylene Glycol Monomethyl Ether)
A 3 L flask equipped with a stirrer, thermometer, and dehydration tube was charged with 500 g of succinic anhydride, 4235 g of hexaethylene glycol monomethyl ether, and 9.5 g of paratoluenesulfonic acid monohydroxide, and nitrogen (500 mL / min) was added to the space. While blowing, the reaction was carried out at 150 ° C. under reduced pressure (4 to 10.7 kPa) for 40 hours. The acid value of the reaction solution was 1.6 (mgKOH / g). After adding 27 g of adsorbent KYOWARD 500SH (manufactured by Kyowa Chemical Industry Co., Ltd.) to the reaction liquid and stirring and filtering at 80 ° C. and 2.7 kPa for 45 minutes, hexaethylene at a liquid temperature of 200 to 280 ° C. and a pressure of 0.003 kPa. After distilling off the glycol monomethyl ether and cooling to 80 ° C., the remaining liquid was filtered under reduced pressure to obtain a diester [(MeEO ₆ ) ₂ SA] of succinic acid and hexaethylene glycol monomethyl ether as a filtrate. The obtained diester had a weight average molecular weight of 674, a viscosity (23 ° C.) of 42 mPa · s, an acid value of 0.2 mgKOH / g, a saponification value of 166 mgKOH / g, a hydroxyl value of 1 mgKOH / g or less, and a hue of APHA280. In addition, this plasticizer is an ester compound with the alcohol which added 6 mol of ethylene oxide per hydroxyl group.

Plasticizer Production Example 4 (MeSA-1,3PD, oligoester compound of dimethyl succinate and 1,3-propanediol)
A 4-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube and nitrogen blowing tube) was charged with 86.8 g (1.14 mol) of 1,3-propanediol and a methanol solution 2 containing 28 wt% sodium methoxide as a catalyst. 0.2 g (0.011 mol of sodium methoxide) was added, and methanol was distilled off with stirring at normal pressure and 120 ° C. for 0.5 hour. Thereafter, 500 g (3.42 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped over 2 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 2 hours to distill off methanol, and the pressure was returned to normal pressure. Further, 28 wt% sodium methoxide-containing methanol was used as a catalyst. 2.0 g of solution (0.010 mol of sodium methoxide) was added, and methanol was distilled by gradually lowering the pressure from normal pressure to 2.9 kPa over 3 hours at 100 ° C. Then, after cooling to 80 ° C., 6 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 vacuum filtration. The filtrate was heated at a pressure of 4.5 kPa and the temperature was raised from 114 ° C. to 194 ° C. over 1 hour to distill off the remaining dimethyl succinate, thereby obtaining a room temperature yellow liquid. In addition, the usage-amount of the catalyst was 0.61 mol with respect to 100 mol of dicarboxylic acid ester. The plasticizer is an ester compound represented by formula (I) (R ¹ is a methyl group, R ² is an ethylene group, R ³ is a propylene group, m is 1, and n is 1.5). .

Examples 1-12 and Comparative Examples 1-6
Preparation of Polylactic Acid Resin Composition As a polylactic acid resin composition, the composition raw materials shown in Tables 1 and 2 were converted into a twin-screw extruder (Perker, HK25D, cylinder diameter 25.2 mm, rotation speed 100 rpm, discharge amount 8 kg / h), melt kneading at a melt kneading temperature of 180 to 190 ° C., strand cutting was performed, and pellets of a polylactic acid resin composition were obtained. The obtained pellets were dried at 110 ° C. under reduced pressure for 2 hours, and the water content was adjusted to 500 ppm or less.

Preparation of sheet-like molded body The obtained pellet or mixture was formed into a sheet having a width of 400 mm under the following conditions using a T-die extruder (manufactured by Plastic Engineering Laboratory Co., Ltd., 500 mm T-die).
<Extrusion conditions>
Cylinder temperature of biaxial kneading part: 180 ° C
T-die (outlet) temperature: 180 ° C
Extrusion speed: 8kg / h (Cooling roll contact time is 34 seconds)
Cooling roll surface temperature: 25 ° C
Heating roll surface temperature: 80 ° C
Sheet thickness: 0.4 mm

  The characteristics of the obtained sheet-like molded body were evaluated according to the methods of Test Examples 1 to 3 below. The results are shown in Tables 1-2.

Test Example 1 <Crystallinity>
From the molded sheet, 10 mg is precisely weighed and sealed in an aluminum pan. Then, using a differential scanning calorimeter “DSC8500” (manufactured by PerkinElmer), 1stRUN is set to 25 ° C. to 200 ° C. at a temperature rising rate of 15 ° C./min. The temperature was raised and held at 200 ° C. for 1 minute, then the temperature was lowered from 200 ° C. to 25 ° C. at a temperature drop rate of −500 ° C./minute, held at 25 ° C. for 1 minute, and further increased to 2ndRUN to a temperature increase rate of 15 ° C./minute. After the temperature was raised from 25 ° C. to 200 ° C., the absolute value ΔHc of the cold crystallization enthalpy of the polylactic acid resin observed at 1stRUN was obtained, and the crystal melting enthalpy ΔHm observed at 2ndRUN was obtained. Was used to determine the relative crystallinity (%), and the crystallinity was evaluated.
Relative crystallinity (%) = {(ΔHm−ΔHc) / ΔHm} × 100

Test example 2 <impact resistance>
A sample of 5 cm × 5 cm × 0.4 mm is prepared from the molded sheet, and a DuPont type drop impact tester (No.517-L made by Yasuda Seiki Seisakusho, the maximum drop height is 1000 mm, the interval is 50 mm, the diameter is 19.05 mm) 50% impact fracture energy measured in an atmosphere at a temperature of 23 ° C. according to JIS-K7211-1 (2006) using a mold, a cradle with a diameter of 19.05 mm, and a drop weight of 100 to 1000 g was used as impact strength. It shows that it is excellent in impact resistance, so that the numerical value of impact strength is large.

Test Example 3 <Transparency>
A sample of 5 cm × 5 cm × 0.4 mm was prepared from the molded sheet, and the haze value was measured using an integrating sphere light transmittance measuring device (HM-150 Murakami Color Research Laboratory) defined in JIS-K7105. A small Haze value indicates good transparency.

In addition, the raw material in Tables 1-2 is as follows.
[Polylactic acid resin]
Nature Works 4032D: Poly-L-lactic acid (optical purity 98.5%, melting point 166 ° C., weight average molecular weight 180000)
[Plasticizer]
(MeEO ₃ ) ₂ SA: Diester compound produced in Production Example 1 of the plasticizer (MeEO ₄ ) ₂ SA: Diester compound produced in Production Example 2 of the plasticizer (MeEO ₆ ) ₂ SA: Production of the plasticizer Diester compound MeSA-1, 3PD produced in Example 3: Oligoester compound DAIFACTY-101 produced in Production Example 4 of the plasticizer: ester of adipic acid, benzyl alcohol and methyl diglycol, Pluronic manufactured by Daihachi Chemical Industry Co., Ltd. F68: Polyethylene glycol / polypropylene glycol copolymer, manufactured by ADEKA [Fatty acid alkanolamide]
C12 diethanolamide: Lauric acid diethanolamide, Amizole LDE-G, Kawaken Fine Chemical Co., Ltd. C14 diethanolamide: Myristic acid diethanolamide, Amizole MDE, Kawaken Fine Chemical Co., Ltd. C18 (saturated) diethanolamide: Stearic acid diethanolamide, Amizole SDE C18 (unsaturated) diethanolamide manufactured by Kawaken Fine Chemical Co., Ltd .: oleic acid diethanolamide, Amisole ODE, C12 monoethanolamide manufactured by Kawaken Fine Chemical Co., Ltd .: palm oil fatty acid monoethanolamide (main component: lauric acid monoethanolamide), Amizole CME, C12 monoisopropanolamide manufactured by Kawaken Fine Chemical Co., Ltd .: lauric acid monoisopropanolamide, Amizole PLME-A, Kawaken Phi Chemical Co., Ltd. [impact modifier]
BPM-515: Paraloid BPM-515, acrylic core shell rubber, manufactured by Rohm and Haas [Crystal nucleating agent]
SLIPAX H: Ethylene bis 12-hydroxystearic acid amide, manufactured by Nippon Kasei Co., Ltd. [hydrolysis inhibitor]
Carbodilite LA-1: Polycarbodiimide, manufactured by Nisshinbo Chemical Co., Ltd.

  From the results of Tables 1 and 2, it can be seen that the polylactic acid resin composition of the present invention is excellent in both impact resistance and transparency.

  The polylactic acid resin composition of the present invention can be suitably used for various applications such as food containers, packaging materials for daily necessities and household appliances, trays for industrial parts, and the like.

Claims (6)

A polylactic acid resin composition comprising (A) a polylactic acid resin, (B) a plasticizer, and (C) a fatty acid alkanolamide,
The (B) plasticizer is an ester compound having two or more ester groups in the molecule, and at least one of the alcohol components constituting the ester compound is an alkylene oxide having 2 or 3 carbon atoms per hydroxyl group. A polylactic acid resin composition comprising one or more selected from the group consisting of an ester compound which is an alcohol added with an average of 0.5 mol or more and 8 mol or less and an ester compound represented by the following formula (I).
R ¹ O—CO—R ² —CO — [(OR ³ ) _m O—CO—R ² —CO—] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 or 3 carbon atoms, and m is 1 A number of 6 or less and n represents a number of 1 to 12 inclusive, provided that all R ² may be the same or different, and all R ³ may be the same or different.   (B) Polylactic acid resin composition of Claim 1 whose content of a plasticizer is 0.5 mass part or more and 15 mass parts or less with respect to 100 mass parts of (A) polylactic acid resin.   (C) A fatty acid alkanolamide is a condensation product of a fatty acid having 10 to 22 carbon atoms and one or more selected from the group consisting of monoethanolamine, diethanolamine, monoisopropanolamine, and diisopropanolamine. The polylactic acid resin composition according to claim 1 or 2, comprising:   (C) The polylactic acid resin composition in any one of Claims 1-3 whose addition amount of fatty-acid alkanolamide is 0.05 mass part or more and 5 mass parts or less with respect to 100 mass parts of (A) polylactic acid resin.   A sheet-like molded article comprising the polylactic acid resin composition according to any one of claims 1 to 4 and having a relative crystallinity of 80% or more. The manufacturing method of the sheet-like molded object of Claim 5 including the following process (1) and (2).
Step (1): A step of preparing a polylactic acid resin composition by melting and kneading a raw material containing (A) a polylactic acid resin, (B) a plasticizer, and (C) a fatty acid alkanolamide, ) The plasticizer is an ester compound having two or more ester groups in the molecule, and at least one alcohol component constituting the ester compound is an average of 0 or 2 alkylene oxides having 2 or 3 carbon atoms per hydroxyl group. A process comprising one or more selected from the group consisting of an ester compound which is an alcohol added with 5 mol or more and 8 mol or less and an ester compound represented by the following formula (I): R ¹ O—CO—R ² —CO - _{^{[(OR 3) m O-CO}} -R 2 -CO- ] _n OR ¹ (I)
Wherein R ¹ is an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is an alkylene group having 2 or 3 carbon atoms, and m is 1 A number of 6 or less and n represents a number of 1 to 12 inclusive, provided that all R ² may be the same or different, and all R ³ may be the same or different.
Step (2): Step of extruding the polylactic acid resin composition obtained in Step (1)