JP5836703B2 - Polylactic acid resin composition and molded article - Google Patents

Description

  The present invention relates to a polylactic acid resin composition and a molded body formed by molding the same.

  In recent years, biodegradable polyester resins have attracted attention from the viewpoint of environmental conservation. Among the biodegradable polyester resins, polylactic acid resin, polyethylene succinate, polybutylene succinate and the like are low in cost and highly useful because they can be mass-produced.

  In particular, polylactic acid resin can already be produced from plants such as corn and sweet potato, and even if incinerated after use, considering the carbon dioxide absorbed during the growth of these plants, the carbon balance is neutral. Therefore, it is considered as a resin having a particularly low load on the global environment.

  However, polylactic acid resin itself has the property of being easily combusted and being inferior in heat resistance. For this reason, there is a safety problem when this is used alone for an application requiring flame retardancy or heat resistance, such as a housing of an electric product or the like. In addition, since the polylactic acid resin has a low crystallization rate, there is a problem that a molding cycle is long.

  Patent Document 1 already describes that a molded article having excellent heat resistance can be obtained by adding an organic filler and a flame retardant to a polylactic acid resin and performing injection molding at a mold temperature of 90 ° C. . Specifically, it is disclosed that a molded product having flame resistance of V-2 to V-0 and heat resistance that a deflection temperature under load (0.45 MPa) is around 100 ° C. is obtained in the UL94 combustion test. ing. In this method, heat resistance is improved by adding 20% or more of waste paper powder as an organic filler. However, the molded article disclosed in Patent Document 1 cannot be discolored by heat at the time of melting during kneading or molding, and it is difficult to adjust the color tone. Furthermore, in this molded article, no consideration is given to satisfying the excellent flame retardancy of V-0 and shortening the afterflame time after flame contact. In addition, when used as a casing of an electric product or the like, if the afterflame time is long, there is a safety problem such as fear of ignition.

  Patent Document 2 discloses that a molded article having flame retardancy and heat resistance can be obtained by adding a hydroxide subjected to surface treatment to a polylactic acid resin. However, in the molded article disclosed in Patent Document 2, since it is necessary to blend a large amount of hydroxide, the use may be limited in fields where lightness is required. Moreover, in this molded object, since the flame retardance obtained is V-2 and the obtained heat resistance is a deflection temperature under load of 50 ° C. or higher (1.8 MPa), flame retardancy and heat resistance are required. Is still inadequate for use in the intended applications.

  Patent Document 3 discloses a resin composition in which a borate is added to a polylactic acid resin. Specifically, a resin composition containing a fiber impregnated with sodium borate and a polylactic acid resin is disclosed. The flame retardancy level in this resin composition is V-1, and the heat resistance level is a deflection temperature under load of 100 ° C. or lower, that is, the flame retardancy and heat resistance are insufficient.

Japanese Patent Laid-Open No. 2005-23260 JP-A-2005-139441 JP 2007-231034 A

  An object of the present invention is to provide a polylactic acid resin composition that is excellent in heat resistance and flame retardancy and maintains mechanical properties.

式中、Ｘ_１、Ｘ_２、Ｘ_３、Ｘ_４は、水素、水酸基、アミノ基、アルコキシ基、フェニル基、アミノ基、アリル基のいずれかを表す。また、ｎは３〜１０の整数を表す。
また、式中、Ｙは、−Ｎ＝Ｐ（ＯＣ_６Ｈ_５）_３、または−Ｎ＝Ｐ（Ｏ）ＯＣ_６Ｈ_５を表し、Ｚは−Ｐ（ＯＣ_６Ｈ_５）_４、または、−Ｐ（Ｏ）（ＯＣ_６Ｈ_５）_２を表す。
（３）ポリ乳酸樹脂（Ａ）中のＤ体含有量が１．０モル％以下であるか、または９９．０モル％以上であることを特徴とする（１）または（２）のポリ乳酸樹脂組成物。
（４）（１）〜（３）のポリ乳酸樹脂組成物を成形してなる成形体。 The present inventor has conducted extensive studies in order to solve the above problems, polylactic acid resins, polylactic acid resin composition phosphite Fazen compound and-phosphate melamines is contained in a specific ratio, the The present inventors have found that the problem can be solved and have reached the present invention.
That is, the gist of the present invention is as follows.
(1) 5-100 parts by mass of phosphazene compound (B) and melamine phosphate (C) in total with respect to 100 parts by mass of polylactic acid resin (A), and phosphazene compound (B) and melamine phosphate content ratio of s (C) is, in mass ratio, (phosphazene compound) / (melamine phosphate compound) = 90 / 10-50 / 50 der is, phosphoric acid melamine (C) is melamine polyphosphate, polyphosphoric At least one of melamine acid, melam, melem, and
For 100 parts by mass of the polylactic acid resin (A), at least one of an organic amide compound, an organic hydrazide compound, a carboxylic acid ester compound, an organic sulfonate, and an organic phosphonate as an organic crystal nucleating agent (D) one, polylactic acid resin composition characterized that you containing from 0.1 to 5 parts by weight of total.
(2) The polylactic acid resin according to (1), wherein the phosphazene compound (B) is a cyclic phosphazene compound represented by the formula (1) and / or a chain phosphazene compound represented by the formula (2) Composition.

In the formula, X ₁ , X ₂ , X ₃ , and X ₄ represent any of hydrogen, a hydroxyl group, an amino group, an alkoxy group, a phenyl group, an amino group, and an allyl group. N represents an integer of 3 to 10.
Further, in the formula, Y _{is, -N = P (OC 6 H} 5) represents ₃ or _{-N = P (O) OC 6} H 5,, Z is -P _{(OC 6} H _{5) 4,} or - It represents a _{P (O) (OC 6 H} 5) 2.
(3) The polylactic acid according to (1) or (2), wherein the D-form content in the polylactic acid resin (A) is 1.0 mol% or less, or 99.0 mol% or more Resin composition .
(4 ) A molded article obtained by molding the polylactic acid resin composition of (1) to ( 3 ).

  According to the present invention, since the phosphazene compound and melamine phosphate are contained in a specific ratio, the polylactic acid resin can be imparted with flame retardancy and heat resistance, excellent in flame retardancy and heat resistance, A polylactic acid resin composition having maintained mechanical properties can be provided. In addition, when a polylactic acid resin having a D-form content in a specific range is used as the polylactic acid resin, the polylactic acid resin has improved crystallinity, improved moldability, and better heat resistance. It can be a composition. Crystallinity can also be improved by using an organic crystal nucleating agent. The polylactic acid resin composition of the present invention can be suitably used for applications that require flame retardancy and heat resistance, such as housings for electrical products, and uses a polylactic acid resin that is a low environmental load material. The range can be greatly expanded, and the industrial utility value is extremely high.

Hereinafter, the present invention will be described in detail.
The polylactic acid resin composition of the present invention (sometimes referred to simply as “resin composition” in the present specification) is composed of phosphazene compound (B) and melamine phosphate with respect to 100 parts by mass of the polylactic acid resin (A). 5 to 25 parts by mass in total, and the content ratio of the phosphazene compound (B) and the melamine phosphate (C) is (phosphazene compound) / (melamine phosphate) = 90/10 to 50/50.

First, the polylactic acid resin (A) will be described.
The polylactic acid resin (A) refers to poly (L lactic acid), poly (D lactic acid), a mixture or a copolymer thereof.

  Polylactic acid resin has high heat resistance among aliphatic polyesters. In order to further improve the heat resistance, the D-form content of the polylactic acid resin (A) is preferably 1.0 mol% or less, or 99.0 mol% or more. Especially, it is preferable that D body content is 0.1-0.6 mol% or 99.4-99.9 mol%.

  The D-form content of the polylactic acid resin (A) refers to the ratio (mol%) occupied by the D lactic acid unit in the total lactic acid units constituting the polylactic acid resin (A). Therefore, for example, in the case of a polylactic acid resin having a D-form content of 1.0 mol%, in this polylactic acid resin, the proportion of D lactic acid units is 1.0 mol%, and the proportion of L lactic acid units is 99.0 mol%.

  In the present invention, the D-form content of the polylactic acid resin (A) is calculated by the following method. That is, it is calculated by a method in which all of L lactic acid and D lactic acid obtained by decomposing polylactic acid resin (A) are methyl esterified, and the methyl ester of L lactic acid and the methyl ester of D lactic acid are analyzed by a gas chromatography analyzer. The

  The polylactic acid resin (A) in which the D-form content satisfies the above range is improved in crystallinity, thereby improving the crystallization speed. Therefore, when molding the resin composition of the present invention, the molding cycle is shortened and the moldability is excellent. And it becomes possible to obtain the molded object excellent in heat resistance.

Furthermore, if the D-isomer content was used polylactic acid resin (A) satisfying the above range, depending phosphazene compound (B) and-phosphate melamines the (C) to be contained in a specific ratio In addition, the effect of improving flame retardancy is particularly noticeable. The reason is because the polylactic acid resin D-isomer content satisfies the above range (A) is excellent in crystallinity, in obtaining the molded body, the phosphazene compound (B) and-phosphate melamine (C ) Is activated, and it is assumed that the effect of imparting flame retardancy is further improved.

  The polylactic acid resin (A) is produced by a known melt polymerization method or by further using a solid phase polymerization method. In addition, as the polylactic acid resin (A) satisfying the specific D-form content as described above, a commercially available product may be used, or among the lactides that are cyclic dimers of lactic acid, the D-form content. Using a L-lactide having a sufficiently low L content or a D-lactide having a sufficiently low L-form content as a raw material, and using a known melt polymerization method or a solid phase polymerization method. Also good.

  Moreover, it is preferable that the melt flow rate (MFR) in 190 degreeC and load 21.2N of a polylactic acid resin (A) is 0.1-50 g / 10min, More preferably, it is 0.2-20 g / 10min. And optimally 0.5 to 10 g / 10 min. If the MFR exceeds 50 g / 10 min, the melt viscosity is too low and the mechanical properties and heat resistance when formed into a molded product may be inferior. Moreover, since the load at the time of a shaping | molding process becomes it high that MFR is less than 0.1 g / 10min, operativity may fall. In addition, said MFR is a value by JISK7210 (test condition D).

  As a method for controlling the MFR of the polylactic acid resin (A) to the above range, when the MFR is too large, a small amount of chain extender, for example, a diisocyanate compound, a bisoxazoline compound, an epoxy compound, an acid anhydride, or the like is used. A method for increasing the molecular weight of the resin may be mentioned. On the contrary, when MFR is too small, the method of mixing with the polyester resin and low molecular weight compound which have larger MFR is mentioned.

  The polylactic acid resin (A) may be copolymerized with monomers other than the lactic acid component, which is the main component. Examples of the copolymerizable monomer include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,5 as acid components. -Naphthalenedicarboxylic acid, methyl terephthalic acid, 4,4'-biphenyl dicarboxylic acid, 2,2'-biphenyl dicarboxylic acid, 4,4'-biphenyl ether dicarboxylic acid, 4,4-diphenylmethane dicarboxylic acid, 4,4'- Aromatic dicarboxylic acids such as diphenylsulfone dicarboxylic acid and 4,4'-diphenylisopropylidenedicarboxylic acid; adipic acid, sebacic acid, oxalic acid, malonic acid, succinic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, aikosan diacid Saturated aliphatic dicarboxylic acids such as acids and hydrogenated dimer acids; Unsaturated aliphatic dicarboxylic acids such as malic acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, and dimer acid and their anhydrides; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2 -Cycloaliphatic dicarboxylic acid, 2,5-norbornene dicarboxylic acid, and alicyclic dicarboxylic acids such as tetrahydrophthalic acid.

  Examples of the copolymerizable monomer include ethylene glycol, propylene glycol, 1,3-butanediol, diethylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8 as diol components. Aliphatic diols such as octanediol and 1,10-decanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and 1,2-cyclohexanedimethanol, bisphenol A and bisphenol Bisphenols such as S or their ethylene oxide adducts; and aromatic diols such as hydroquinone and resorcinol.

  Furthermore, as copolymerizable monomers, hydroxycarboxylic acids such as p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, 6-hydroxycaproic acid, 3-hydroxybutyric acid, and 3-hydroxyvaleric acid; -Lactone compounds such as valerolactone, γ-butyrolactone, and ε-caprolactone.

  And it is preferable that the polylactic acid resin (A) in this invention is acetone-treated and the amount of residual lactide is 700 ppm or less. By using the polylactic acid resin (A) that has been subjected to acetone treatment and the residual lactide content is 700 ppm or less, the resin composition of the present invention has further improved crystal performance, more heat resistance and moldability. It will be improved.

  Acetone treatment is to wash the polylactic acid resin with acetone and extract unreacted lactide. As the cleaning method with acetone, the following method is preferable. Both are mixed so that the mass ratio of the polylactic acid resin and acetone is (polylactic acid) :( acetone) = 1: 1 to 1: 3, and the mixture is stirred for 30 minutes or more with a stirring blade or the like. Stir. In addition, the temperature at the time of stirring has the preferable range of 0 degreeC-60 degreeC, Especially, it is 10 degreeC-40 degreeC, More preferably, it is 20 degreeC-30 degreeC. When the stirring temperature exceeds 60 ° C., since the boiling point of acetone is exceeded, the volatilization of acetone increases. When the stirring temperature is less than 0 ° C., acetone must be cooled, which is disadvantageous in terms of cost.

  The stirring speed of the stirring blade is preferably 50 to 1000 rpm, more preferably 100 to 500 rpm, and more preferably 150 to 300 rpm. When it exceeds 1000 rpm, the stirring speed is too high, and the generation of dust increases due to the violent collision of the resins. When it is less than 10 rpm, the amount of lactide extracted into acetone decreases, and the treatment time becomes long.

  In general, other solvents such as methanol can also be used to extract unreacted lactide in the polylactic acid resin. However, in the present invention, by using acetone as a solvent, unreacted lactide can be extracted and at the same time the crystallization rate of the polylactic acid resin can be improved.

  Acetone is a relatively inexpensive solvent and is advantageous in terms of cost, and it is possible to extract not only lactide but also low molecular oligomers in polylactic acid resin. Further, since lactic acid is not detected from the residue after the treatment and the extract does not decompose and become lactic acid and is stable, it is advantageous in terms of cost when considering the reuse of lactide. From these, it is presumed that the effect of improving the crystallization speed of the polylactic acid resin as described above occurs.

  When other solvent such as methanol is used instead of acetone, a large amount of lactic acid is detected from the residue. For this reason, when lactic acid remains in the resin, problems such as molecular weight reduction may occur during processing and storage, and such polylactic acid resin does not improve the crystallization rate.

  Further, as a method for removing unreacted lactide in the polylactic acid resin, a method of removing lactide by a single screw extruder, a twin screw extruder or the like is also common. However, even when lactide is removed by these methods, low-molecular oligomers remain in the polylactic acid resin, and the resulting polylactic acid resin does not have an improved crystallization rate.

The polylactic acid resin (A) in the present invention is preferably subjected to the acetone treatment as described above so that the amount of residual lactide in the resin is 700 ppm or less, and more preferably 500 ppm or less. . When the amount of residual lactide exceeds 700 ppm, the effect of improving the crystallization rate may be reduced, and molecular weight may be reduced or coloring may occur during melt processing.

The amount of residual lactide of the polylactic acid resin (A) is measured and calculated as follows. First, 9 ml of methylene chloride and 1 ml of an internal standard solution (5000 ppm solution of 2,6-dimethyl-γ-pyrone) are added to 0.1 g of a sample to dissolve the polymer. 40 ml of cyclohexane is added to the polymer solution to precipitate the polymer. After filtration through an HPLC disk filter (pore size 0.45 μm), GC measurement is performed with a 7890A GC System manufactured by Agilent Technologies, and the lactide content is calculated.

  In the resin composition containing the polylactic acid resin (A), the phosphazene compound (B) and the melamine phosphates (C), when measuring the amount of residual lactide of the polylactic acid resin (A), the same as described above. Can be measured and calculated. At this time, the resin composition is used as a sample.

The polylactic acid resin composition of the present invention, the polylactic acid resin (A), contained amount phosphazene compound is a flame retardant (B) and-phosphate melamines (C) satisfies the specific ratio As a result, different flame retardant effects that are manifested by each of them are produced, specifically excellent flame retardancy is imparted, and heat resistance is also imparted.

  Compared with other resins, polylactic acid resin has a property that it is easy to drip during combustion and a carbonized layer is hardly formed. However, in the present invention, by using the phosphazene compound and melamine phosphate together with the polylactic acid resin, the content is smaller than when the phosphazene compound and melamine phosphate are each contained alone in the resin composition. Can provide excellent flame retardancy.

  Although the clear mechanism by which such an effect is achieved is unknown, it is presumed that it is due to the following reason. In other words, the phosphazene compound that is generally blended as an accelerator for carbonization, the resin composition of the present invention captures oxygen radicals generated during combustion or hydrogen radicals to extinguish in the gas phase. This is presumed to be effective. Furthermore, melamine phosphates dilute the oxygen concentration with nitrogen, an inert gas contained in melamine during combustion, and form a carbonized layer with phosphoric acid, resulting in a heat insulation effect and oxygen barrier effect. Presumed to be.

  In addition, when a phosphazene compound (B) and melamine phosphates (C) are each used alone, sufficient flame retardancy cannot be imparted. If the phosphazene compound (B) and the melamine phosphates (C) are used singly and their content relative to the polylactic acid resin (A) is increased from the content specified in the present invention, The flame retardancy is improved to some extent, but the mechanical properties and heat resistance are inferior.

  The total content of the phosphazene compound (B) and the melamine phosphates (C) needs to be 5 to 25 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A), and 10 to 20 parts by mass. It is more preferable that When the content of the phosphazene compound (B) and the melamine phosphate (C) is less than 5 parts by mass, flame retardancy and heat resistance cannot be imparted. On the other hand, if it exceeds 25 parts by mass, the flame-retardant effect is saturated, and no further effect can be found. Moreover, there exists a problem that heat resistance and a molding cycle will also fall.

  Furthermore, the content ratio of the phosphazene compound (B) and the melamine phosphates (C) is a mass ratio of [phosphazene compound (B)] / [melamine phosphates (C)] = 90 / 10-50 / 50. It is necessary to be, and among them, 85/15 to 70/30 is preferable. Only when the content ratio of the phosphazene compound (B) and the melamine phosphates (C) is within the above range, it is possible to impart heat resistance in addition to flame retardancy. Although this mechanism is not clear, when the phosphazene compound (B) and the melamine phosphate (C) are blended at a specific ratio, crystallization of the polylactic acid resin (A) is promoted, and further, the phosphazene compound (B). It is presumed that the heat resistance of the resin composition is improved when the melamine phosphates (C) and the melamine phosphates function well as an inorganic filler.

  In the present invention, a phosphazene compound (B) containing a phosphorus atom and a nitrogen atom in the molecule is used. Among them, from the viewpoint of flame retardancy, a chain phosphazene compound represented by the formula (1), And / or a cyclic phosphazene compound represented by formula (2) is preferred.

In the formula, X ₁ , X ₂ , X ₃ , and X ₄ represent any one of hydrogen, a hydroxyl group, an amino group, an alkoxy group, a phenyl group, an amino group, and an allyl group. N represents an integer of 3 to 10. In the formula, Y represents —N═P (OC ₆ H ₅ ) ₃ or —N═P (O) OC ₆ H ₅ , and Z represents —P (OC ₆ H ₅ ) ₄ or —P (O) (OC ₆ H ₅ ) ₂ is represented.

  As the phosphazene compound (B), a commercially available product can be suitably used. Specifically, “SPR-100”, “SA-100”, “SPB-100”, “SPB-100L” (hereinafter referred to as Otsuka). Chemicals), "FP-100", "FP-110" (Fushimi Pharmaceutical Co., Ltd.).

  The content ratio of the phosphazene compound (B) is preferably 2.5 to 22.5 parts by mass, more preferably 5 to 18 parts by mass with respect to 100 parts by mass of the polylactic acid resin. When the content ratio is less than 2.5 parts by mass, it becomes difficult to impart flame retardancy. On the other hand, if it exceeds 22.5 parts by mass, flame resistance may be imparted, but heat resistance, durability, and moldability tend to decrease.

  Further, as the melamine phosphates (C), those having an average particle diameter of 10 μm or less by laser diffraction method are preferably used. For the measurement of the average particle size, a laser diffraction particle size distribution measuring device (manufactured by Sympatech) can be used. When this average particle diameter exceeds 10 μm, it may be difficult to develop mechanical strength and flame retardancy.

The melamine phosphates (C) used in the present invention is at least one of melamine polyphosphate, melamine polyphosphate, melam, and melem, and commercially available melamine phosphates (C) are preferably used. Specific examples thereof include “Melapur 200/70” (melamine polyphosphate) (manufactured by Ciba Specialty Chemicals, average particle size 8 μm), PHOSMEL-200 (melamine polymelate melam melem) (Nissan Chemical Industry Co., Ltd.) Manufactured, average particle size 7 μm), and apinone MPP-A (melamine polyphosphate) (manufactured by Sanwa Chemical Co., Ltd., average particle size 4 μm).

  The content ratio of the melamine phosphates (C) is preferably 0.5 to 12.5 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the polylactic acid resin. When it is less than 0.5 parts by mass, it becomes difficult to impart flame retardancy. On the other hand, when it exceeds 12.5 parts by mass, the mechanical strength and heat resistance tend to be lowered even if flame retardancy can be imparted.

  In addition to the above components, the polylactic acid resin composition of the present invention preferably further contains an organic crystal nucleating agent (D) from the viewpoint of promoting the crystallization of polylactic acid and improving the molding cycle. When only the crystal nucleating agent other than the organic crystal nucleating agent is used, the effect of promoting crystallization may be insufficient, and the molding cycle may become long.

  The organic crystal nucleating agent (D) needs to be an organic amide compound, an organic hydrazide compound, a carboxylic acid ester compound, an organic sulfonate, or an organic phosphonate from the viewpoints of moldability and heat resistance.

  A commercially available organic crystal nucleating agent (D) as described above can be suitably used. Specifically, “AS-A-T-530SF” manufactured by Ito Oil Co., Ltd., “Eco Promote NP” manufactured by Nissan Chemical Co., Ltd., “LAK-403”, “LAK-301” manufactured by Takemoto Yushi Co., Ltd., etc. Can be mentioned. These can be contained alone or in combination of two or more. In particular, Eco Promote NP and LAK-403 are preferable from the viewpoint of the crystallization promoting effect.

  0.1-5 mass parts is preferable with respect to 100 mass parts of polylactic acid resins, and, as for the content rate of an organic type crystal nucleating agent (D), 0.5-2 mass parts is more preferable. If the content is less than 0.1 part by mass, the crystallization promoting effect may be poor. On the other hand, if it exceeds 5 parts by mass, the effect of promoting crystallization is saturated and not only economically disadvantageous, but also the residue after biodegradation may increase.

  Moreover, the resin composition of this invention may contain other resin components other than polylactic acid resin (A) in the range which does not impair the effect of this invention. Moreover, when using the resin composition of this invention, the resin composition of this invention and another resin component can also be mix | blended and used.

  Examples of such other resin components include polyamide, polyethylene, polypropylene, polybutadiene, polystyrene, acrylonitrile / styrene copolymer resin, acrylonitrile / butadiene / styrene copolymer resin, poly (acrylic acid), poly (acrylic ester), poly Non-aliphatic polyester resins such as (methacrylic acid), poly (methacrylic acid ester), polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and copolymers thereof.

  Furthermore, the polylactic acid resin composition of the present invention includes pigments, heat stabilizers, antioxidants, inorganic fillers, plant fibers, reinforcing fibers, weathering agents, lubricants, mold release agents, as long as the properties are not impaired. Additives such as antistatic agents, impact modifiers, plasticizers, and reactive compounds can be added.

Examples of the pigment include titanium and carbon black.
Examples of heat stabilizers and antioxidants include hindered phenols, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like.

  Examples of the inorganic filler include talc, mica, calcium carbonate, zinc carbonate, wollastonite, alumina, magnesia, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, Examples include zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, carbon fiber, and layered silicate. The gas barrier property of a resin composition can be improved by mix | blending layered silicate.

Examples of plant fibers include kenaf fibers, bamboo fibers, jute fibers, and other cellulosic fibers.
Examples of reinforcing fibers include organic reinforcing fibers such as aramid fibers, polyarylate fibers, and liquid crystal polymer fibers.

Examples of weathering agents include benzotriazole and benzoxazinone.
As the lubricant, various carboxylic acid compounds can be used, and among them, various fatty acid metal salts, particularly magnesium stearate and calcium stearate are preferable.

As the mold release agent, various carboxylic acid compounds, particularly, various fatty acid esters, various fatty acid amides, and the like are preferably used.
The impact resistance improver is not particularly limited, and various types such as a (meth) acrylic ester impact resistance agent having a core-shell structure can be used.

  The content ratio of the impact resistance improver is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the polylactic acid resin from the viewpoints of impact resistance, moldability, and heat resistance.

  Among the above additives, the plasticizer is contained for the purpose of imparting flexibility to the polylactic acid resin. Specific examples of plasticizers include glycerin diacetomonolaurate, glycerin diacetomonocaprate, polyglycerin acetate, polyglycerin fatty acid ester, medium chain fatty acid triceride, dimethyl adipate, dibutyl adipate, triethylene glycol diacetate, acetylricinoleic acid Examples thereof include methyl, acetyltributylcitric acid, polyethylene glycol, dibutyldiglycol succinate, bis (butyldiglycol) adipate, bis (methyldiglycol) adipate, and adipic acid ester.

  It is preferable that the content rate of a plasticizer is 0.05-20 mass parts with respect to 100 mass parts of polylactic acid resin from a heat resistant, a flame retardance, and a softness | flexibility viewpoint.

  The reactive compound is preferably, for example, a carbodiimide compound. By containing the carbodiimide compound, the heat-and-moisture resistance is improved, the compatibility by melt kneading is further improved, and the mechanical properties are also improved.

  Various compounds can be used as the carbodiimide compound, and there are no particular limitations as long as it has one or more carbodiimide groups in the molecule. Examples of the carbodiimide compound include aliphatic monocarbodiimide, aliphatic polycarbodiimide, alicyclic monocarbodiimide, alicyclic polycarbodiimide, aromatic monocarbodiimide, aromatic polycarbodiimide, and the like. Furthermore, you may have various heterocyclic rings or various functional groups in a molecule | numerator.

  The content ratio of the carbodiimide compound 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 heat and humidity resistance, heat resistance and cost.

  The method for producing the polylactic acid resin composition of the present invention is not particularly limited as long as each component is uniformly dispersed. For example, after uniformly dry blending using a tumbler or Henschel mixer, melt kneading and extrusion may be performed, followed by cooling, cutting, and drying steps to form pellets. In melt kneading, a general kneader such as a single screw extruder, a twin screw extruder, a roll kneader, or a Brabender can be used.

  The means for mixing the polylactic acid resin (A), the phosphazene compound (B), the melamine phosphates (C) and other additives as required is not particularly limited. For example, a uniaxial or biaxial extruder is used. Examples thereof include a method of melt kneading. In order to improve the kneading state, it is preferable to use a twin screw extruder. The kneading temperature is preferably {[melting point of polylactic acid resin (A)] + 5} ° C. to {[melting point of polylactic acid resin (A)] + 100} ° C. When the temperature is lower than this range, kneading and reaction become insufficient. On the other hand, when the temperature is higher than this range, the resin may be decomposed or colored. The kneading time is preferably 20 seconds to 30 minutes. If the time is shorter than this time, the kneading or reaction becomes insufficient. On the other hand, if the time is longer than this time, the resin may be decomposed or colored.

  The polylactic acid resin composition of the present invention is formed by injection molding, blow molding, extrusion molding, inflation molding, injection blow molding, foamed sheet molding, and molding methods such as vacuum molding, pressure molding, and vacuum / pressure molding after sheet processing. Various molded bodies can be obtained. That is, a molded body formed by injection molding, or a film or sheet formed by extrusion molding, a molded body formed by processing these films or sheets, or a hollow body formed by blow molding, and from this hollow body It can be set as the molded object etc. which are processed. Among the above, it is particularly preferable to adopt an injection molding method, and in addition to a general injection molding method, gas injection molding, injection press molding, and the like can also be employed.

  If an example of the injection molding conditions suitable for the polylactic acid resin composition of this invention is given, it is preferable that a cylinder temperature shall be more than melting | fusing point or flow start temperature of a resin composition, for example, 170-250 degreeC, for example, 170-230 degreeC More preferably. The mold temperature is suitably (melting point of the resin composition−40) ° C. or lower. If the molding temperature is too lower than the above-mentioned range of the cylinder temperature or the mold temperature, a short circuit may occur in the molded product, which may cause the operability to become unstable or easily fall into an overload. On the other hand, if the molding temperature is too high exceeding the above-mentioned cylinder temperature or mold temperature range, the resin composition will decompose, causing problems such as reduction in the strength of the resulting molded product or coloring. It is easy to do and may not be preferable.

  The polylactic acid resin composition of the present invention can further improve heat resistance by promoting crystallization during molding. As a method of promoting crystallization, for example, there is a method of promoting crystallization in a mold at the time of injection molding. In that case, the glass transition temperature of the resin composition or higher (melting point −40 of the resin composition) A method in which the molded body is held for a certain period of time in a mold kept at a temperature of 0 ° C. or lower and then removed from the mold is suitable. Further, even if the molded body is taken out from the mold without taking such a method, the molded body is heat-treated at a temperature not lower than the glass transition temperature of the resin composition and not higher than (melting point of the resin composition −40) ° C. By doing so, crystallization can be promoted.

  Specific examples of molded articles using the polylactic acid resin composition of the present invention include PC casing parts and casings, mobile phone casing parts and casings, and other appliances such as OA equipment casing parts and connectors. Resin parts: Automotive plastic parts such as bumpers, instrument panels, console boxes, garnishes, door trims, ceilings, floors, panels around engines, agricultural materials such as containers and cultivation containers, and resin parts for agricultural machinery; Resin parts for fishery products such as processed fishery products containers; dishes and food containers such as dishes, cups and spoons; medical resin parts such as syringes and infusion containers; housings such as drain materials, fences, storage boxes, construction switchboards, etc. Resin parts for civil engineering and construction materials; Resin parts for greening materials such as flowerbed bricks and flower pots; Resin parts for leisure and miscellaneous goods such as cooler boxes, fan fans and toys Ballpoint, ruler, stationery resin parts such as clips and the like.

  The molded body of the present invention can be particularly suitably used in parts and the like that require heat resistance and flame retardancy.

Hereinafter, the present invention will be described more specifically with reference to examples.
The measurement methods used for evaluating the resin compositions obtained in the examples and comparative examples are as follows.

(1) D-form content of polylactic acid resin (A) 0.3 g of polylactic acid resin taken out from the obtained resin composition was weighed and added to 6 mL of 1N potassium hydroxide / methanol solution, and sufficient at 65 ° C. Stir. Subsequently, 450 μL of sulfuric acid was added and stirred at 65 ° C. to decompose polylactic acid, and 5 mL was measured as a sample. To this sample, 3 mL of pure water and 13 mL of methylene chloride were mixed and shaken. After stationary separation, about 1.5 mL of the lower organic layer was collected, filtered through a HPLC disk filter having a pore size of 0.45 μm, and then subjected to gas chromatography measurement using HP-6890 Series GC system (manufactured by Hewlett Packard). The ratio (%) of the peak area of D lactate methyl ester to the total peak area of lactate methyl ester was calculated, and this was defined as the D form content (mol%) of the polylactic acid resin.

(2) MFR of polylactic acid resin (A)
According to JIS K 7210 (test condition D), the measurement was performed at 190 ° C. and a load of 21.1 N.

(3) Bending strength The pellets of the obtained resin composition were vacuum-dried at 70 ° C. for 24 hours, and then the mold surface temperature was set to 105 using an injection molding machine (“IS-80G type” manufactured by Toshiba Machine Co., Ltd.). While adjusting to ° C., an ISO-compliant test piece was prepared.
It measured according to ISO178 using the obtained test piece. The bending strength is preferably 65 MPa or more.

(4) Flexural modulus Measured according to ISO178 using a test piece obtained in the same manner as (3). The flexural modulus is preferably 3.0 GPa or more.

(5) Heat resistance Using the test piece obtained in the same manner as in (3), the deflection temperature under load (DTUL) was measured at a load of 0.45 MPa according to ISO75-1. The deflection temperature under load is preferably 80 ° C. or higher.

(6) Flame retardancy A test piece having a thickness of 1/16 inch (about 1.6 mm) was produced under the same conditions as in the method for producing a test piece described in (3). Using this test piece, the measurement was performed according to the method of UL94 (standard defined by Under Writers Laboratories Inc. in the United States). The flame retardancy is preferably V-1 or V-0. For this reason, those that did not become V-1 or V-0 were judged to be inferior in flame retardancy and were marked "X".

(7) Formability (molding cycle)
An ISO dumbbell-shaped test piece was produced using an injection molding machine (“IS-80G” manufactured by Toshiba Machine Co., Ltd.) using the pellets of the resin composition obtained. Specifically, it was melted at a molding temperature of 190 ° C., and a mold having a mold temperature of 95 ° C. was filled with the molten resin. Molding cycle is good because the resin composition is injected into the mold (filling, holding pressure) and cooled, and then the molded body can be fixed to the mold or taken out without resistance, and there is no deformation due to the protruding pin. The required time (seconds) until release was possible. The molding cycle is preferably 60 seconds or less.

(8) Durability (Bending strength retention)
Two test pieces obtained in (3) were prepared, and one was measured for bending strength by the same method as in (3) above (assumed untreated bending strength). The other was subjected to a storage treatment for 300 hours under a constant temperature and humidity condition of 60 ° C. and 95% RH, and then the bending strength was measured by the same method as (3) above (referred to as the bending strength after the treatment). And bending strength retention was computed with the following formula | equation.
Bending strength retention (%) = [(Bending strength after treatment) / (Untreated bending strength)] × 100
Based on the bending strength retention rate, the following criteria were used for evaluation.
A: Bending strength retention is 90% or more.
○: Bending strength retention is 80% or more and less than 90%.
Δ: Bending strength retention is less than 80%.

  Moreover, the various raw materials used for the Example and the comparative example are as follows.

(1) Polylactic acid resin (A)
・ PLA-1
Product name “Nature Works 3001D” (manufactured by Nature Works) (MFR: 10 g / 10 min, melting point: 168 ° C., D-form content: 1.4 mol%)
・ PLA-2
S-12 manufactured by Toyota Motor Corporation (MFR = 8 g / 10 min, melting point: 178 ° C., D-form content = 0.1 mol%, residual lactide content = 1100 ppm)
・ PLA-3
PLA-2 was subjected to acetone treatment as follows to obtain PLA-3.
Measurement was performed so that the mass ratio of PLA-2 to acetone was 1: 2, and acetone was added to PLA-2, followed by stirring at 150 rpm for 1 hour at room temperature. Thereafter, the mixture was filtered and vacuum-dried at 70 ° C. for 24 hours (using Yamato Vacuum dry DP61) to remove acetone to obtain polylactic acid (PLA-3). The amount of residual lactide of the obtained PLA-3 was 400 ppm.

(2) Phosphazene compound (B)
・ Product name “Ravitor FP-110” (melting point 110 ° C.) manufactured by Fushimi Pharmaceutical Co., Ltd. (hereinafter referred to as “FP-110”)
FP-110 is a cyclic phosphazene compound represented by the formula (1). In the formula (1), X ₁ and X ₂ represent phenyl groups, and n = 3 is the main component.

(3) Melamine phosphates (C)
・ Product name “Melapur 200/70” (average particle size: 8 μm) manufactured by Ciba Specialty Chemicals (hereinafter referred to as “Melapur”)
・ Product of Nissan Chemical Co., Ltd., trade name “Phosmel-200” (average particle size: 7 μm) (hereinafter referred to as “Phosmel”)
・ Product name “Apinon MPP-B” (average particle size: 12 μm) manufactured by Sanwa Chemical Co., Ltd. (hereinafter referred to as “MPP”)

(4) Flame retardants other than phosphazene compounds (B) and melamine phosphates (C) Aluminum hydroxide manufactured by Nippon Light Metal Co., Ltd., trade name “B1403T”

(5) Other additives (organic crystal nucleating agent)
・ Product name “Eco Promote-NP” (Zinc Phenylphosphonate) (hereinafter referred to as “NP”) manufactured by Nissan Chemical Co., Ltd.
・ Product name “LAK-403” (barium sulfonate) (hereinafter referred to as “LAK”) manufactured by Takemoto Yushi Co., Ltd.

(Inorganic crystal nucleating agent)
・ Product name “MICRO ACE K-1” (average particle size 7.4 μm) (hereinafter referred to as “K-1”) manufactured by Nippon Talc Co., Ltd.

(Carbodiimide compound)
・ Made by Matsumoto Yushi Co., Ltd., trade name “EN-160”

Example 1
Using a twin screw extruder (“TEM37BS type” manufactured by Toshiba Machine Co., Ltd.), polylactic acid resin (A), phosphazene compound (B), melamine phosphates (C) and other additives as shown in Table 1 The product was dry blended so as to have the content shown in Table 1, and supplied to the extruder from the root supply port. Melt extrusion was carried out while venting under the conditions of a barrel temperature of 190 ° C., a screw speed of 200 rpm, and a discharge rate of 15 kg / h. The molten resin discharged from the extruder tip was taken up in a strand shape, passed through a vat filled with cooling water, cooled, and then cut into a pellet shape to obtain a resin composition pellet.

(Examples 2-28, Comparative Examples 1-11)
The polylactic acid resin (A), the phosphazene compound (B), the melamine phosphates (C), other additives, and their contents were changed as shown in Tables 1 to 4 and the same as in Example 1. Thus, pellets of the resin composition were obtained. The evaluation results of the examples are shown in Tables 1, 2 and 3, and the evaluation results of the comparative examples are shown in Table 4.

  Tables 1 to 4 show the compositions and evaluation results of the resin compositions obtained in Examples 1 to 28 and Comparative Examples 1 to 11.

  In Tables 1 to 4, the unit of numerical values related to the composition of the resin composition is parts by mass.

  As is clear from Tables 1, 2 and 3, the polylactic acid resin compositions obtained in Examples 1 to 28 contain the phosphazene compound (B) and melamine phosphates (C) in a specific ratio. Therefore, it was excellent in heat resistance and flame retardancy.

  The polylactic acid resin compositions obtained in Examples 9 to 13 were excellent in heat resistance and molding cycle because the polylactic acid resin (A) having a low D-form content was used.

  The polylactic acid resin compositions obtained in Examples 14 to 15 were particularly excellent in heat resistance and moldability because the polylactic acid resin (A) in which the residual amount of lactide was reduced by acetone treatment was used. .

  The polylactic acid resin composition obtained in Example 23 was inferior in durability because no carbodiimide compound was used, but it was excellent in other characteristics and could withstand practical use sufficiently. there were.

  In the polylactic acid resin composition obtained in Example 26, since an inorganic crystal nucleating agent was used instead of the organic crystal nucleating agent (D), there was room for improvement in the molding cycle and flame retardancy. Met.

  In the polylactic acid resin composition obtained in Example 27, the content of the organic crystal nucleating agent (D) was less than the preferred range of the present invention, but the polylactic acid resin (A) having a low D-form content. Therefore, it was possible to suppress a decrease in the molding cycle and sufficiently withstand practical use.

  In the polylactic acid resin composition obtained in Example 28, since an inorganic crystal nucleating agent was used instead of the organic crystal nucleating agent (D), there was room for improvement in flame retardancy. . However, since the polylactic acid resin (A) having a low D-form content was used, the reduction in the molding cycle could be suppressed.

  On the other hand, since the polylactic acid resin composition obtained in Comparative Example 1 had a high content of the phosphazene compound (B), some flame retardancy was imparted, but melamine phosphates (C) were used. The result was inferior in heat resistance.

  Since the polylactic acid resin composition obtained in Comparative Example 2 had a high content of melamine phosphates (C), some flame retardancy was imparted, but the phosphazene compound (B) was not used. The result was inferior in heat resistance.

  The polylactic acid resin composition obtained in Comparative Example 3 was inferior in heat resistance and flame retardancy because melamine phosphates (C) were not used.

  Since the polylactic acid resin composition obtained in Comparative Example 4 did not use the phosphazene compound (B), the results were inferior in heat resistance and flame retardancy.

  In the polylactic acid resin composition obtained in Comparative Example 5, the total content of the phosphazene compound (B) and the melamine phosphates (C) was too small, resulting in poor heat resistance and flame retardancy. It was.

  The polylactic acid resin composition obtained in Comparative Example 6 was inferior in heat resistance and molding cycle because the total content of the phosphazene compound (B) and melamine phosphates (C) was excessive. .

  The polylactic acid resin compositions obtained in Comparative Examples 7 and 8 were inferior in heat resistance and flame retardancy because the content of the phosphazene compound (B) relative to the melamine phosphates (C) was too small. .

  Since the content of the phosphazene compound (B) with respect to the melamine phosphate (C) was excessive, the polylactic acid resin composition obtained in Comparative Example 9 resulted in poor heat resistance and flame retardancy.

  The polylactic acid resin composition obtained in Comparative Example 10 was inferior in heat resistance and flame retardancy because aluminum hydroxide was used as a flame retardant instead of melamine phosphates (C).

  The polylactic acid resin composition obtained in Comparative Example 11 was inferior in heat resistance and flame retardancy because aluminum hydroxide was used as a flame retardant instead of the phosphazene compound (B).

Claims (4)

A total of 5 to 25 parts by mass of the phosphazene compound (B) and melamine phosphates (C) is contained with respect to 100 parts by mass of the polylactic acid resin (A), and the phosphazene compound (B) and melamine phosphates (C content of) is, in mass ratio, (phosphazene compound) / (melamine phosphate compound) = 90 / 10-50 / 50 der is, phosphoric acid melamine is (C), melamine polyphosphate, melamine polyphosphate At least one of melam melem, and
For 100 parts by mass of the polylactic acid resin (A), at least one of an organic amide compound, an organic hydrazide compound, a carboxylic acid ester compound, an organic sulfonate, and an organic phosphonate as an organic crystal nucleating agent (D) one, polylactic acid resin composition characterized that you containing from 0.1 to 5 parts by weight of total. 2. The polylactic acid resin composition according to claim 1, wherein the phosphazene compound (B) is a cyclic phosphazene compound represented by the formula (1) and / or a chain phosphazene compound represented by the formula (2). object.

In the formula, X ₁ , X ₂ , X ₃ , and X ₄ represent any of hydrogen, a hydroxyl group, an amino group, an alkoxy group, a phenyl group, an amino group, and an allyl group. N represents an integer of 3 to 10.
Further, in the formula, Y _{is, -N = P (OC 6 H} 5) represents ₃ or _{-N = P (O) OC 6} H 5,, Z is -P _{(OC 6} H _{5) 4,} or - It represents a _{P (O) (OC 6 H} 5) 2.   The polylactic acid resin composition according to claim 1 or 2, wherein the D-form content in the polylactic acid resin (A) is 1.0 mol% or less, or 99.0 mol% or more. . The molded object formed by shape | molding the polylactic acid resin composition in any one of Claims 1-3 .