JP2013249323A - Polylactic acid resin composition - Google Patents

Abstract

The present invention relates to a polylactic acid resin composition that can suppress bleed while satisfying flame retardancy and impact resistance, a molded product obtained from the composition, and a method for producing the same.
The polylactic acid resin (A) has a triaryl phosphate (B) and two ester groups in the molecule, and the carboxylic acid component constituting the ester is an aliphatic dicarboxylic acid having 4 to 8 carbon atoms. And an alcohol component is blended with a plasticizer (C) which is a compound obtained by adding an average of 0 to 2 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group, and the triaryl phosphate (B) and the plastic The polylactic acid resin composition whose mass ratio (plasticizer / triaryl phosphate) of an agent (C) is 0.1-0.9.
[Selection figure] None

Description

  The present invention relates to a polylactic acid resin composition. More specifically, the present invention relates to a polylactic acid resin composition that can be suitably used as a home appliance part such as a casing of an information home appliance, a molded body obtained by injection molding the composition, and a method for producing the same.

  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.

  Patent Document 1 discloses a polylactic acid resin composition containing a phosphorus-based flame retardant excluding a polylactic acid resin, a plasticizer, a crystal nucleating agent, and a phenylphosphonic acid metal salt, and two or more plasticizers in the molecule. Is a compound in which at least one alcohol component constituting the ester is an average of 0.5 to 5 moles of an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group, and the crystal nucleating agent is specified A polylactic acid resin composition which is a mixture of the two types of crystal nucleating agents is disclosed.

  Further, in Patent Document 2, in order to provide a flame-retardant and impact-resistant polylactic acid resin composition excellent in heat resistance, the main component is polylactic acid resin, and 3 to 30% by mass of triphenyl phosphates. A polylactic acid resin composition characterized by melting and kneading a mixture containing 0.01 to 5% by mass of a (meth) acrylic acid ester compound and 0.001% by mass or more of a peroxide is disclosed. .

  Patent Document 3 discloses a polylactic acid resin, a metal hydroxide, a phosphorus compound, and a volatilization other than the phosphorus compound in order to provide a polylactic acid resin composition having an excellent balance between flame retardancy and bleeding properties. A polylactic acid resin composition is disclosed in which the content of the phosphorus compound is 10 parts by mass or less with respect to a total value of 100 parts by mass of the polylactic acid resin.

JP 2009-270090 A JP 2008-101084 A WO2011 / 155119 pamphlet

  However, in patent documents 1 and 2, although the flame retardance of the obtained molded object is excellent, there exists a subject that a phosphorus flame retardant etc. bleed from a molded object. Moreover, although it is described in patent document 3 that the bleeding of a phosphorus compound can be suppressed, the compounding quantity of a phosphorus compound is limited and there exists a subject that impact resistance is not enough.

  The present invention relates to a polylactic acid resin composition capable of suppressing bleed while satisfying flame retardancy and impact resistance, a molded article obtained from the composition, and a method for producing the same.

The present invention relates to the following [1] to [2].
[1] The polylactic acid resin (A) has a triaryl phosphate (B) and two ester groups in the molecule, and the carboxylic acid component constituting the ester is an aliphatic dicarboxylic acid having 4 to 8 carbon atoms. The triaryl phosphate (B) and the plasticizer, wherein the alcohol component is a compound obtained by adding an average of 0 to 2 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group. The polylactic acid resin composition whose mass ratio (plasticizer / triaryl phosphate) of (C) is 0.1-0.9.
[2] A molded product obtained by injection molding the polylactic acid resin composition according to [1].

  The polylactic acid resin composition of the present invention can provide a molded article having excellent bleeding properties while satisfying flame retardancy and impact resistance.

  The polylactic acid resin composition of the present invention is obtained by blending a triaryl phosphate (B) and a specific plasticizer (C) in a specific amount ratio with a polylactic acid resin (A). In the present specification, the “formulation” means “formulation or inclusion”.

  Triaryl phosphate is excellent in flame retardancy and impact resistance, but triaryl phosphate tends to bleed when blended with polylactic acid resin. In this invention, it discovered that generation | occurrence | production of a bleed | bread was suppressed and flame retardance and impact resistance improved further by mix | blending the specific plasticizer used as a specific ratio with respect to triaryl phosphate. The reason for this is unknown, but the inclusion of a specific plasticizer makes the polylactic acid resin hydrophobic and dramatically improves the compatibility of the triaryl phosphate, resulting in excellent bleed resistance and flame retardancy. It is thought that shows. Furthermore, it is considered that the specific plasticizer and triaryl phosphate synergistically improve the flexibility of the polylactic acid resin, increase the crystallinity, and express high impact resistance.

  Hereinafter, each component will be described.

[Polylactic acid resin (A)]
As the polylactic acid resin (A) in the polylactic acid resin composition of the present invention, a commercially available polylactic acid resin (for example, Mitsui Chemicals, trade names: Lacia H-100, H-280, H-400, H -440 etc., manufactured by Nature Works, trade name: Nature Works PLA / NW3001D, NW4032D, etc.), and polylactic acid resin synthesized from lactic acid and lactide according to a known method. From the viewpoint of improvement in strength and heat resistance, a polylactic acid resin having an optical purity of preferably 90% or more, more preferably 95% or more is preferable. For example, a polylactic acid resin having a relatively high molecular weight and a high optical purity is manufactured by Nature Works. Lactic acid resin (NW4032D etc.) is preferable. The optical purity is a ratio of mol% occupied by L-form or D-form in polylactic acid resin.

  In the present invention, the polylactic acid resin contains a crosslinked polylactic acid resin obtained by previously kneading polylactic acid resin and polycarbodiimide at 180 to 230 ° C. (also referred to as melt-kneading). It is preferable from the viewpoint. That is, a part or all of the polylactic acid resin (A) is a crosslinked polysiloxane obtained by kneading polylactic acid resin and polycarbodiimide in advance at 180 to 230 ° C. (also referred to as melt kneading) from the viewpoint of bleeding resistance. A lactic acid resin is preferred. The content of the crosslinked polylactic acid resin in the polylactic acid resin containing the crosslinked polylactic acid resin is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, and still more preferably 70 to 100% by mass.

  Specific examples of the polycarbodiimide include poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (diisopropylphenylcarbodiimide), and poly (triisopropylphenylcarbodiimide). ), Etc .; alicyclic polycarbodiimides such as poly (dicyclohexylmethanecarbodiimide); aliphatic polycarbodiimides, and from the viewpoint of increasing the reactivity with the polylactic acid resin (a), aromatic polycarbodiimide and An alicyclic polycarbodiimide is preferable, and at least one selected from poly (dicyclohexylmethanecarbodiimide) and poly (diisopropylphenylcarbodiimide) is more preferable. These polycarbodiimides can be used alone or in combination of two or more.

  When kneading the polylactic acid resin and the polycarbodiimide, the amount of polycarbodiimide used is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the polylactic acid resin, from the viewpoint of bleeding resistance, and 0.25 to 2 Mass parts are more preferable, and 0.25 to 1.5 parts by mass are more preferable.

  The kneading of the polylactic acid resin and the polycarbodiimide can be performed by a known melt kneader. As the melt kneader, a uniaxial or biaxial continuous kneader, a batch kneader using a roll mill, an open roll kneader, or the like can be used, and a uniaxial or biaxial continuous kneader is preferable. Examples of such a kneader include a KTK type twin screw extruder manufactured by Kobe Steel, a TEM type extruder manufactured by Toshiba Machine Co., a twin screw extruder manufactured by Kay Sea Kay, a Kneader manufactured by Buss, and Ikekai Tekko. A PCM type twin-screw extruder manufactured by Tosho Co., Ltd. is preferably used.

  The kneading temperature (melt kneading temperature) of the polylactic acid resin and polycarbodiimide is preferably 180 to 230 ° C, more preferably 190 to 220 ° C, and further preferably 195 to 220 ° C. When a melt kneader is used, it means the set temperature of the kneader when melt kneading. Moreover, before melt-kneading, the polylactic acid resin and polycarbodiimide can be mixed mechanically and uniformly. The method of mechanically and uniformly mixing the polylactic acid resin and polycarbodiimide can be carried out under normal conditions using a mixer having a normal stirring blade, and the means is not particularly limited.

  Kneading depends on the scale of the melt kneader, but is preferably about 10 seconds to 5 minutes, more preferably about 20 seconds to 3 minutes.

  The completion of the kneading can be confirmed by measuring the carboxyl group terminal concentration. The carboxyl group terminal concentration of the obtained polylactic acid resin (A) is preferably 20 mmol / kg or less, more preferably 15 mmol / kg or less, further preferably 12 mmol / kg or less, from the viewpoint of impact resistance and bleed resistance. More preferably, it is 10 mmol / kg or less. Although there is no lower limit in particular, it is preferably 3 mmol / kg or more from the viewpoint of productivity. From these viewpoints, it is preferably 3-20 mmol / kg, more preferably 3-15 mmol / kg, still more preferably 3-12 mmol / kg. kg, more preferably 3 to 10 mmol / kg. The carboxyl group terminal concentration can be measured by the method described later.

  In the present invention, in addition to the polylactic acid resin (A), other biodegradable resins may be appropriately contained as long as the effects of the present invention are not impaired. Examples of other biodegradable resins include polyester resins such as polybutylene succinate, polyhydroxyalkanoic acid, and the like. Moreover, a part or all of the polylactic acid resin (A) may be contained as a polymer alloy by blending with the other biodegradable resin or a non-biodegradable resin such as polypropylene. 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 blending amount of the polylactic acid resin (A) in the polylactic acid resin composition is preferably 30 to 80% by mass from the viewpoint of impact resistance, making the strength and flexibility of the polylactic acid resin composition compatible. 75 mass% is more preferable, and 40-70 mass% is further more preferable. In the present specification, when the polylactic acid resin (A) is simply indicated, for example, when the polylactic acid resin (A) includes a crosslinked polylactic acid resin, it means the entire polylactic acid resin including the crosslinked polylactic acid resin, In this case, the blending amount of the polylactic acid resin (A) means the total amount of the crosslinked polylactic acid resin and the other polylactic acid resin. In the present specification, the “blending amount” means “blending amount or content”.

[Triaryl phosphate (B)]
The triaryl phosphate (B) used in the present invention is a triaryl phosphate containing at least one alkylaryl group having an alkyl group having 1 or 2 carbon atoms from the viewpoint of flame retardancy, impact resistance, and bleed resistance. In particular, the following general formula:
(R ¹ R ² ArO) _x (ArO) _3-x PO
(In the formula, Ar represents a benzene ring, and R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms, except that when both are hydrogen atoms, x is 1; Represents an integer of ~ 3)
The compound represented by these is preferable.

As R ¹ and R ² in the above formula, when both are methyl groups, when R ¹ is an ethyl group and R ² is a hydrogen atom, R ¹ may be a methyl group and R ² may be a hydrogen atom. preferable.

  X in the formula represents an integer of 1 to 3, but an integer of 1 to 2 is preferable, and 1 is more preferable. That is, the compound represented by the above formula is a compound containing one or more, preferably 1-2, more preferably one alkylaryl group having an alkyl group having 1 or 2 carbon atoms.

  Specific examples of the triaryl phosphate represented by the above formula include trixylenyl phosphate, tricresyl phosphate, dixylenyl phenyl phosphate, dicresyl phenyl phosphate, xylenyl diphenyl phosphate, and cresyl diphenyl phosphate. . These can be used alone or in combination of two or more, i.e., trixylenyl phosphate, tricresyl phosphate, dixylenyl phenyl phosphate, dicresyl phenyl phosphate, xylenyl diphenyl phosphate, and cresyl diphenyl phosphate It may be at least one selected from the group consisting of, and cresyl diphenyl phosphate is preferred in consideration of the flame retardancy, impact resistance and bleed resistance of the polylactic acid resin composition containing triaryl phosphate.

  The blending amount of the triaryl phosphate (B) in the polylactic acid resin composition is preferably 10 parts by mass or more, more preferably 100 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A) from the viewpoint of impact resistance and bleed resistance. Is 15 parts by mass or more, more preferably 20 parts by mass or more, further preferably 22 parts by mass or more, preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 28 parts by mass or less. Moreover, from the same viewpoint, Preferably it is 10-35 mass parts, More preferably, it is 10-30 mass parts, More preferably, it is 15-30 mass parts, More preferably, it is 20-30 mass parts, More preferably, it is 22-28 masses Part. Flame retardancy and impact resistance are good at 12 parts by mass or more, and bleed resistance is good at 35 parts by mass or less. In addition, the compounding quantity of a triaryl phosphate (B) is a compounding quantity of the triaryl phosphate (B) contained in the polylactic acid resin composition of this invention, and when there are two or more triaryl phosphates (B) Means the total amount.

[Plasticizer (C)]
The plasticizer (C) used in the present invention has two ester groups in the molecule from the viewpoint of flame retardancy, impact resistance, and bleed resistance, and the carboxylic acid component constituting the ester Is an aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and an alcohol component is a compound obtained by adding an average of 0 to 2 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group. When the alcohol component is a compound in which an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group is added at an average of 2 mol or less, the bleed resistance is good.

  The carboxylic acid component may be an aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and from the viewpoint of bleed resistance and moldability, one or more selected from the group consisting of succinic acid, adipic acid, and suberic acid. Aliphatic dicarboxylic acids are preferred, and adipic acid is more preferred.

  The alcohol component may be a compound obtained by adding an average of 0 to 2 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group. From the viewpoint of bleeding resistance, the number of carbon atoms is preferably 2 to 10, and more preferably. Is preferably a compound of 4-8. In addition, the carbon number here is the total number of carbon atoms in one molecule of the alcohol compound.

  Specifically, from the viewpoints of bleed resistance and moldability, polyethylene glycol monoalkyl ether (preferably an average addition mole number of alkylene oxide of 1 to 2) and / or aromatic alcohol (preferably an average addition mole number of alkylene oxide). 0) is preferable, and it is more preferable that both polyethylene glycol monoalkyl ether and aromatic alcohol are included.

  The number of carbon atoms of the monoalkyl ether of the polyethylene glycol monoalkyl ether is preferably 1 to 4, more preferably 1 to 2, from the viewpoints of bleed resistance and moldability. The polyethylene glycol of polyethylene glycol monoalkyl ether is preferably diethylene glycol, triethylene glycol, or tetraethylene glycol.

  As the aromatic alcohol, benzyl alcohol and cresol are preferable.

  These alcohol components can be used singly or in combination of two or more. From the viewpoint of bleeding resistance, it is preferable to use polyethylene glycol monoalkyl ether and an aromatic alcohol in combination. This is because polyethylene glycol monoalkyl ether is considered to be excellent in compatibility with polylactic acid resin, and aromatic alcohol is considered to be excellent in compatibility with triaryl phosphate.

  Specific examples of the ester compound of the carboxylic acid component and the alcohol component include diethylene glycol monomethyl ether / benzyl alcohol adipic acid diester (diester of adipic acid and an alcohol component containing diethylene glycol monomethyl ether and benzyl alcohol), benzyl Alcohol adipic acid diester, diethylene glycol monomethyl ether adipic acid diester, diethylene glycol monomethyl ether / cresol adipic acid diester, diethylene glycol monomethyl ether / benzyl alcohol succinic acid diester, diethylene glycol monomethyl ether / benzyl alcohol suberic acid diester, etc. From the viewpoint of impact resistance and bleed resistance, Glycol monomethyl ether / benzyl alcohol diester of adipic acid is preferable.

  The compounding amount of the plasticizer (C) in the polylactic acid resin composition is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and further preferably 4 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A). It is above, Preferably it is 10 mass parts or less, More preferably, it is 9 mass parts or less, More preferably, it is 8 mass parts or less. Moreover, Preferably it is 2-10 mass parts, More preferably, it is 2-9 mass parts, More preferably, it is 3-8 mass parts, More preferably, it is 4-8 mass parts. When it is 2 parts by mass or more, flame retardancy and impact resistance are good, and when it is 10 parts by mass or less, bleeding resistance is good. Moreover, in this invention, in the range which does not impair the effect of this invention, other well-known plasticizers other than the said plasticizer (C) can be used. In addition, the compounding quantity of a plasticizer (C) is a compounding quantity of the plasticizer (C) contained in the polylactic acid resin composition of this invention, and when there are two or more plasticizers (C), it is total Means the amount.

  The mass ratio of the triaryl phosphate (B) to the plasticizer (C) (plasticizer / triaryl phosphate) in the polylactic acid resin composition is from the viewpoint of impact resistance, flame retardancy, and bleed resistance. The upper limit is 0.9 or less, preferably 0.4 or less, and more preferably 0.38 or less. Moreover, it is 0.1-0.9, Preferably it is 0.1-0.4, More preferably, it is 0.14-0.38. When the ratio is 0.1 or more, the bleed resistance is excellent, and when it is 0.9 or less, the flame retardancy and the impact resistance are excellent.

[Carbodiimide compound (D)]
In addition to the said component, it is preferable to mix | blend the carbodiimide compound with the polylactic acid resin composition of this invention from the viewpoint of impact resistance, bleed resistance, and a flame retardance. Examples of the carbodiimide compound include monocarbodiimide compounds and polycarbodiimide compounds similar to those used for the preparation of the polylactic acid resin (A), and these can be used alone or in combination of two or more.

  As monocarbodiimide compounds, diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, di-2,6-ditert-butylphenyl Carbodiimide, di-o-tolylcarbodiimide, di-p-tolylcarbodiimide, di-2,4,6-trimethylphenylcarbodiimide, di-2,4,6-triisopropylphenylcarbodiimide, di-2,4,6-tri Aromatic monocarbodiimide compounds such as isobutylphenylcarbodiimide; Alicyclic monocarbodiimide compounds such as di-cyclohexylcarbodiimide; Aliphatic monocarbodiimides such as di-isopropylcarbodiimide and di-octadecylcarbodiimide Thing, and the like.

  The blending amount of the carbodiimide compound (D) is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A) from the viewpoints of impact resistance, bleed resistance and flame retardancy. 2-5 mass parts is more preferable, and 0.3-3 mass parts is further more preferable. In addition, the compounding quantity of a carbodiimide compound (D) is a compounding quantity of the carbodiimide compound (D) mix | blended with the polylactic acid resin composition of this invention, and polycarbodiimide used for preparation of a crosslinked polylactic acid resin is used. When it is not included and there are a plurality of carbodiimide compounds (D), it means the total amount. The same applies to the following blending mass ratio.

  The blending mass ratio of the carbodiimide compound (D) and the triaryl phosphate (B) blended in the polylactic acid resin composition (carbodiimide compound / triaryl phosphate) is from the viewpoint of impact resistance, bleed resistance, and flame retardancy. Preferably it is 0.01-0.1, More preferably, it is 0.02-0.1, More preferably, it is 0.025-0.067.

[Aluminum hydroxide (E)]
Moreover, in addition to the said component, it is preferable to further mix | blend aluminum hydroxide (E) with the polylactic acid resin composition of this invention from a flame-retardant viewpoint.

  There is no limitation in particular as aluminum hydroxide, A well-known substance is used. In addition, it is preferable that aluminum hydroxide is surface-treated with a silane coupling agent, especially isocyanate silane, in accordance with a known method from the viewpoint of physical properties.

  The compounding amount of aluminum hydroxide (E) is preferably 30 parts by mass or more, more preferably 70 parts by mass or more, from the viewpoint of flame retardancy, with respect to 100 parts by mass of the polylactic acid resin (A). From a viewpoint of property, Preferably it is 120 mass parts or less, More preferably, it is 110 mass parts or less, 30-120 mass parts is preferable from these viewpoints, and 70-110 mass parts is more preferable.

[Organic crystal nucleating agent (F)]
In the present invention, from the viewpoint of improving the crystallization speed of the polylactic acid resin and improving the impact resistance, at least one organic crystal nucleating agent selected from the group consisting of the following (a) to (d): (F) can be used.
(A) From the group consisting of a compound having an isoindolinone skeleton, a compound having a diketopyrrolopyrrole skeleton, a compound having a benzimidazolone skeleton, a compound having an indigo skeleton, a compound having a phthalocyanine skeleton, and a compound having a porphyrin skeleton At least one organic compound selected [referred to as organic crystal nucleating agent (a)]
(B) At least one organic compound selected from the group consisting of carbohydrazides, uracils, and N-substituted ureas (referred to as organic crystal nucleating agent (b))
(C) at least one selected from the group consisting of metal salts of dialkyl aromatic sulfonates, metal salts of phosphoric acid esters, metal salts of phenylphosphonic acids, metal salts of rosin acids, aromatic carboxylic acid amides, and rosin acid amides Species of organic compound [referred to as organic crystal nucleating agent (c)]
(D) At least one organic compound selected from the group consisting of a compound having a hydroxyl group and an amide group in the molecule and a hydroxy fatty acid ester [referred to as organic crystal nucleating agent (d)]

  Among these, the organic crystal nucleating agent (c) and the organic crystal nucleating agent (d) are preferable from the viewpoint of shortening the cooling holding time in the mold.

  0.1-5 mass parts is preferable with respect to 100 mass parts of polylactic acid resin (A), and, as for the compounding quantity of an organic crystal nucleating agent (F), 0.5-3 mass parts is more preferable, 0.7- 3 parts by mass is more preferred, and 0.7-2 parts by mass is even more preferred.

  The polylactic acid resin composition according to the present invention includes, as components other than the above, an inorganic crystal nucleating agent, a filler (inorganic filler, organic filler), a hydrolysis inhibitor, a flame retardant, an antioxidant, and an ultraviolet absorber. In addition, an antistatic agent, an antifogging agent, a light stabilizer, a pigment, an antifungal agent, an antibacterial agent, a foaming agent and the like can be blended within a range not impairing the effects of the present invention. Similarly, it is also possible to add a polymer material or other resin composition within a range that does not impair the effects of the present invention.

  In the melt-kneaded product of the polylactic acid resin composition of the present invention, the polylactic acid resin (A), triaryl phosphate (B), and plasticizer (C) are composed of triaryl phosphate (B) and plasticizer (C). If it mix | blends so that it may become the said specific amount ratio, it can prepare without limitation in particular. For example, polylactic acid resin (A), triaryl phosphate (B), plasticizer (C), and various additives such as carbodiimide compound (D), if necessary, triaryl phosphate (B) and plasticizer (C) Can be prepared by melt-kneading the raw material blended so as to have the above-mentioned specific amount ratio using a known kneader such as a closed kneader, a single or twin screw extruder, and an open roll kneader. it can. 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 addition, when preparing the melt of a polylactic acid resin composition, in order to promote the plasticity of a polylactic acid resin, you may melt-mix in the presence of a supercritical gas.

  From the viewpoint of improving the moldability of the polylactic acid resin composition, the melt kneading temperature is preferably 170 to 240 ° C, more preferably 170 to 220 ° C. The melt-kneading time cannot be generally determined depending on the melt-kneading temperature and the type of the kneader, but is preferably 30 to 120 seconds.

  In addition, after melt-kneading, the melt-kneaded product may be dried according to a known method.

  The polylactic acid resin composition of the present invention has good processability and can be formed into various molded articles according to a known method. As a molding method, a known method can be used. For example, by molding the polylactic acid resin composition of the present invention by injection molding, a molded article excellent in impact resistance, bleed resistance and flame retardancy is provided. be able to. Therefore, this invention also provides the molded object obtained by injection-molding the polylactic acid resin composition of this invention.

  For example, the injection-molded body can be molded by filling the polylactic acid resin composition of the present invention into a mold having a desired shape using an injection molding machine.

[Injection molding machine]
As the injection molding, a known injection molding machine can be used. For example, those having a cylinder and a screw inserted through the cylinder as main components [J110AD-180H (manufactured by Nippon Steel), etc.] can be mentioned. The raw material of the polylactic acid resin composition of the present invention may be supplied to a cylinder and melt-kneaded as it is, or a material previously melt-kneaded may be filled in an injection molding machine.

  The set temperature of the cylinder is preferably 170 to 240 ° C, and more preferably 170 to 220 ° C. When the raw material is melt-kneaded with a cylinder, the set temperature of the melt-kneader means the set temperature of the cylinder. The cylinder is equipped with a heater, and the temperature is adjusted accordingly. The number of heaters differs depending on the model and is not determined unconditionally, but the heater adjusted to the set temperature is a temperature existing on the melt-kneaded product discharge port side (nozzle tip side).

  The mold temperature is preferably 110 ° C. or less, more preferably 90 ° C. or less, and still more preferably 80 ° C. or less from the viewpoint of improving the crystallization speed and improving workability. Moreover, 30 degreeC or more is preferable, 40 degreeC or more is more preferable, and 60 degreeC or more is further more preferable. From this viewpoint, the mold temperature is preferably 30 to 110 ° C, more preferably 40 to 90 ° C, and further preferably 60 to 80 ° C.

  The holding time in the mold is not particularly limited, but from the viewpoint of the productivity of an injection molded article made of the polylactic acid resin composition, for example, in a mold at 80 ° C., 3 to 90 seconds is preferable, and 10 to 80 seconds. Is more preferable.

  As one aspect of the present invention, the following method for producing an injection-molded article is provided.

  As a manufacturing method, what is necessary is just a method including the process of melt-kneading the raw material containing the said polylactic acid resin (A), a triaryl phosphate (B), and a plasticizer (C), and injection-molding, for example, the following The method is preferably used.

Specifically, the manufacturing method which has the following process (1)-(3) is mentioned.
Step (1): Polylactic acid resin and polycarbodiimide are kneaded at 180 to 230 ° C. to obtain polylactic acid resin (A) Step (2): Polylactic acid resin (A) obtained in step (1) and tria Reel phosphate (B) and plasticizer (C) are contained, and the mass ratio of the triaryl phosphate (B) and the plasticizer (C) (plasticizer / triaryl phosphate) is 0.1 to 0.9. Step of preparing a polylactic acid resin composition by melting and kneading a certain raw material (3): a step of injection molding the polylactic acid resin composition obtained in step (2)

  Step (1) is as described above. That is, the polylactic acid resin and polycarbodiimide are kneaded preferably at 180 to 230 ° C., more preferably 190 to 220 ° C., and still more preferably 195 to 220 ° C., to carry out a crosslinking reaction, thereby preparing a polylactic acid resin (A). To do.

  In step (2), the polylactic acid resin (A), triaryl phosphate (B), and plasticizer (C) obtained in step (1) and, if necessary, various additives such as a carbodiimide compound (D) are added. The material to be contained is melt kneaded at 170 to 240 ° C., more preferably 170 to 220 ° C., using a known kneader such as a closed kneader, a single or twin screw extruder, or an open roll kneader. Then, a polylactic acid resin composition is prepared. The method of melt kneading can be performed in the same manner as described above.

  In step (3), the polylactic acid resin composition obtained in step (2) is injection molded. As the injection molding, it can be molded by injecting into a mold in the same manner using a known injection molding machine, for example, an injection molding machine similar to the above.

  The molded article of the polylactic acid resin composition of the present invention thus obtained is excellent in impact resistance, bleed resistance, and flame retardancy, and can be suitably used as home appliance parts such as a casing of information home appliances.

  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.

[Concentration of carboxyl group terminal of polylactic acid resin]
The sample is obtained by dissolving 3 g of a polylactic acid resin in 100 mL of chloroform, adding 50 mL of benzyl alcohol and a small amount of phenolphthalein ethanol solution thereto, and titrating with 0.05 N potassium hydroxide ethanol solution.

Production example 1 of polylactic acid resin (A)
2 parts of polylactic acid resin (a-1) (manufactured by NatureWorks, 4032D, carboxyl group terminal concentration 22 mmol / kg) and 0.5 part of poly (dicyclohexylmethanecarbodiimide) (Nisshinbo Chemical Co., Ltd., Carbodilite LA-1) In a shaft extruder (Ikegai Iron Works, PCM-45), melt kneading is performed at a cylinder set temperature of 200 ° C., a rotation speed of 100 rpm, and a supply rate of 30 kg / h, and strand cutting of the melt-kneaded material is performed to obtain a polylactic acid resin. And polycarbodiimide reacted (cross-linked) to obtain a pellet (diameter: 3 to 4 mm) of polylactic acid resin (A). The carboxyl group terminal concentration of the obtained polylactic acid resin (A) (crosslinked polylactic acid resin) was 7 mmol / kg.

Examples 1-15 and Comparative Examples 1-7
The composition raw materials shown in Tables 1 and 2 were melt-kneaded at 190 ° C. using a directional meshing twin-screw extruder (TEM-41SS manufactured by Toshiba Machine Co., Ltd.), strand-cut, and the polylactic acid resin composition Pellets were obtained. In addition, the obtained pellet was dehumidified and dried at 110 ° C. for 2 hours, and the water content was adjusted to 500 ppm or less.

  Next, the obtained pellet was injection molded using an injection molding machine (J110AD-180H (manufactured by Nippon Steel Works) with a cylinder temperature of 200 ° C., and a test piece with a mold temperature of 80 ° C. and a molding time of 60 seconds. [A prismatic test piece (125 mm × 12 mm × 1.6 mm), (63 mm × 13 mm × 6 mm)] was obtained.

In addition, the raw material in Tables 1-2 is as follows.
[Polylactic acid resin (A)]
Cross-linked polylactic acid resin: Polylactic acid resin NW4032D obtained in Production Example 1: Nature Works 4032D (manufactured by Nature Works)
[Organic crystal nucleating agent]
Eco Promote: unsubstituted phenylphosphonic acid zinc salt (manufactured by Nissan Chemical Industries)
[Triaryl phosphate]
CDP: Cresyl diphenyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.)
Leophos 65: Triaryl phosphate isopropylate (Ajinomoto Fine Techno Co., Ltd.)
〔Flame retardants〕
CR-741: Aromatic condensed phosphate ester (manufactured by Daihachi Chemical Industry Co., Ltd.)
B703: Aluminum hydroxide (made by Nippon Light Metal Co., Ltd.)
[Plasticizer]
Component A: Hexanedioic acid, 1- [2- (2-methoxyethyl) ethyl] 6- (phenylmethyl) ester (Synthesis: 1.0 mol of adipic acid, 1.1 mol of benzyl alcohol, 1.1 mol of methyl diglycol, and further, p-toluene It is obtained by charging sulfonic acid and toluene and carrying out ester reaction under reduced pressure.)
Component B: Hexanedioic acid, 1,6-bis (phenylmethyl) ester
Component C: Hexanedioic acid, 1,6-bis [2- (2-methoxyethyl) ethyl] ester
Component D: Methyltriglycol succinic acid diester (Plasticizer Production Example 1 of JP 2011-153296 A)
PL-019: Glycerin diacetate monocaprate, Riquemar PL-019 (manufactured by Riken Vitamin)
[Carbodiimide compound]
Starvacol I LF: Monocarbodiimide (manufactured by Rhein Chemie)
Starvacol P: Polycarbodiimide (Rhein Chemie)

  The characteristics of the obtained 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 <Evaluation of flame retardancy>
Using a test piece (prism test piece (125 mm × 12 mm × 1.6 mm)), a flame of a gas burner for 10 seconds at the lower end of a vertically held sample based on the safety standard UL94 vertical combustion test procedure of Underwriters Laboratories. A flame test was conducted on five samples in which a flame was contacted, and then combustion was stopped within 30 seconds, and then an indirect flame was further applied for 10 seconds. Based on the judgment standard of UL94 vertical combustion test (UL94V), judgment of V-2, V-1, and V-0 was performed. The judgment criteria are shown below. In addition, about the thing which does not correspond to these criteria, a flame retardance was set to Not.
・ V-0
After any flame contact, no sample continues to burn for more than 10 seconds.
The total combustion time for 10 flames on 5 samples does not exceed 50 seconds.
There is no sample that burns to the position of the clamping clamp.
There is no sample that ignites absorbent cotton placed under the sample and drops burning particles.
After the second flame contact, there is no sample that continues red heat for 30 seconds or more.
・ V-1
No sample continues to burn for more than 30 seconds after any flame contact.
The total burn time for 10 flames on 5 samples does not exceed 250 seconds.
There is no sample that burns to the position of the clamping clamp.
There is no sample that ignites absorbent cotton placed under the sample and drops burning particles.
After the second flame contact, there is no sample that continues red heat for 60 seconds or more.
・ V-2
No sample continues to burn for more than 30 seconds after any flame contact.
The total burn time for 10 flames on 5 samples does not exceed 250 seconds.
There is no sample that burns to the position of the clamping clamp.
Falling of burning particles that ignite absorbent cotton placed under the sample is allowed.
After the second flame contact, there is no sample that continues red heat for 60 seconds or more.

Test Example 2 <Evaluation of impact resistance>
Using a test piece (63 mm × 13 mm × 6 mm) and an Izod impact tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) based on ASTM D256, an impact test was conducted at n = 10 to obtain an Izod impact strength (J / M) and measured their (number) average value. It shows that it is excellent in impact resistance, so that Izod impact strength (J / m) is high.

Test Example 3 <Evaluation of bleed resistance>
A test piece (125 mm × 12 mm × 1.6 mm) was left in a temperature-controlled room for 1 week at a temperature of 60 ° C./humidity of 85%, and the surface appearance was visually observed for the presence of additive bleed and tested. The surface of the piece was confirmed by tracing with a finger, and bleed resistance was evaluated according to the following criteria. The smaller the bleed, the better the bleed resistance.
1: It cannot be confirmed visually, and no liquid adheres even if it is traced with a finger.
2: Although it cannot be confirmed visually, the finger feels a slight liquid adhesion when traced with a finger.
3: Small droplets are visually confirmed on the surface of the molded body. When the finger is traced with the finger, liquid adheres to the finger and liquid streaks are formed on the surface of the molded body.
4: The state in which the entire molded body is wet can be confirmed by visual observation. When the finger is traced, the liquid adheres to the finger, and the surface of the molded body always remains wet.

  From the result of Tables 1-2, the polylactic acid resin composition (Examples 1-15) of this application showed the impact resistance of 56 (J / m) or more. Furthermore, none of the bleeds were observed, excellent bleed resistance was exhibited, and it was possible to achieve flame retardancy of V-2 or higher.

  On the other hand, Comparative Example 1 had a small amount of plasticizer, and the mass ratio of the plasticizer / triaryl phosphate was deviated, bleed suppression was reduced, and impact resistance was also reduced. Comparative Example 2 had a large amount of plasticizer, and the mass ratio of the plasticizer / triaryl phosphate was off, resulting in a decrease in bleed suppression. In Comparative Example 3, the amount of triaryl phosphate was large, and the mass ratio of the plasticizer / triaryl phosphate was deviated, and the bleed suppression was lowered. In Comparative Example 4, the flame retardant was not a triaryl phosphate but a condensed phosphoric acid system, the impact resistance was low, and the bleed property was lowered. In Comparative Examples 5 and 6, the plasticizers were different, and the bleeding properties and impact resistance were lowered.

  From the above results, the polylactic acid resin composition of the present invention in which a specific flame retardant and a specific plasticizer are blended with a polylactic acid resin exhibits excellent bleed resistance, impact resistance, and flame resistance. I understand that.

  The polylactic acid resin composition of the present invention can be suitably used as home appliance parts such as a casing of an information home appliance.

Claims (8)

  The polylactic acid resin (A) has a triaryl phosphate (B) and two ester groups in the molecule, and the carboxylic acid component constituting the ester is an aliphatic dicarboxylic acid having 4 to 8 carbon atoms, and an alcohol A component is blended with a plasticizer (C) that is a compound in which an average of 0 to 2 moles of an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group is added, and the triaryl phosphate (B) and the plasticizer (C) The polylactic acid resin composition whose mass ratio (plasticizer / triaryl phosphate) is 0.1 to 0.9.   The polylactic acid resin composition according to claim 1, wherein the triaryl phosphate (B) contains one or more alkylaryl groups having an alkyl group having 1 or 2 carbon atoms.   The polylactic acid resin composition of Claim 1 or 2 whose triaryl phosphate (B) is 10-35 mass parts with respect to 100 mass parts of polylactic acid resin (A).   The polylactic acid resin composition in any one of Claims 1-3 whose plasticizer (C) is 2-10 mass parts with respect to 100 mass parts of polylactic acid resin (A).   The triaryl phosphate (B) is at least one selected from the group consisting of trixylenyl phosphate, tricresyl phosphate, dixylenyl phenyl phosphate, dicresyl phenyl phosphate, xylenyl diphenyl phosphate, and cresyl diphenyl phosphate. The polylactic acid resin composition according to any one of claims 1 to 4.   The polylactic acid resin composition according to any one of claims 1 to 5, wherein the polylactic acid resin (A) comprises a crosslinked polylactic acid resin obtained by kneading a polylactic acid resin and polycarbodiimide in advance at 180 to 230 ° C. .   The carboxylic acid component is one or more aliphatic dicarboxylic acids selected from the group consisting of succinic acid, adipic acid, and suberic acid, and the alcohol component is a polyethylene glycol monoalkyl ether and / or an aromatic alcohol. The polylactic acid resin composition in any one of 1-6.   The molded object obtained by injection-molding the polylactic acid resin composition in any one of Claims 1-7.