JP2014169385A - Polylactic acid resin composition and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid resin composition high in crystallization temperature, excellent in moldability and heat resistance.SOLUTION: There is provided a polylactic acid resin composition containing polylactic acid of 90 wt.% or more, having crystallization temperatures (peak top temperature:T) at a first and a third temperature decreasing processes each of 155°C or more at measurement of DSC in which a series of steps (1) to (3) of temperature rising, holding and temperature decreasing is repeated three times, and each heat release values (H) of 45 J/g or more. (1) the step of rising temperature from 30°C to 260°C at 20°C/min. (2) the step of holding for 1 minute at 260°C. (3) the step of decreasing temperature from 260°C to 30°C at 20°C/min.

Description

  The present invention relates to a polylactic acid resin composition. More specifically, the present invention relates to a polylactic acid resin composition having a high crystallization speed, excellent heat resistance and molding processability, and a method for producing the same.

  Currently, as part of countermeasures for environmental problems, development of technology for substituting plant raw materials for petroleum raw materials used as materials for industrial products is underway. Examples of plastic materials developed using plant-derived substances as raw materials include polylactic acid (hereinafter sometimes abbreviated as PLA).

Polylactic acid not only uses petroleum as a raw material but also has biodegradability, and thus has attracted attention as a plastic material with a low environmental impact from production to disposal.
However, since polylactic acid has a low crystallization rate, it has a drawback that it tends to be deformed when its glass transition temperature (about 60 ° C.) is exceeded, particularly in injection molding in which stretching is not performed. In order to suppress the deformation, in order to increase the degree of crystallinity, an attempt has been made to increase the mold temperature at the time of injection molding and extend the cooling time in the mold, but this method requires a long molding cycle. Therefore, it has a problem in productivity. Therefore, attempts have been made to improve the moldability and heat resistance by increasing the crystallization speed and crystallinity in order to produce a polylactic acid resin molded product with high productivity and use it in a wide range of applications.

  As a method for increasing the crystallization rate of polylactic acid resin, for example, a method of adding a crystal nucleating agent is often used. The crystal nucleating agent serves as a primary crystal nucleus of the crystalline polymer, promotes crystal growth, refines the crystal size, and increases the crystallization speed. Various crystal nucleating agents for polylactic acid resins are known.

  For example, inorganic particles composed of talc and / or boron nitride having a specific particle size or less (see Patent Document 1, etc.), amide compounds represented by a specific formula (see Patent Document 2, etc.), phosphoric acid represented by a specific formula Metal salts (see Patent Document 3, etc.), phenylphosphonic acid metal salts represented by a specific formula (see Patent Document 4, etc.), urea compounds represented by a specific formula (see Patent Document 5, etc.), represented by a specific formula Oxamide derivatives and isocyanuric acid derivatives (see Patent Document 6 and the like), melamine compounds represented by a specific formula (see Patent Document 7 and the like), sulfonic acid metal salts represented by a specific formula (see Patent Document 8 and the like), and the like Are known.

Further, as a hydrazide-based organic nucleating agent for polylactic acid resin, N-benzoyl hydrazide represented by a specific formula (see Patent Document 9 etc.), hydrazide having a pyridine ring represented by a specific formula (see Patent Document 10 etc.) In addition, sulfohydrazide represented by a specific formula (see Patent Document 11) and the like are known.
These crystal nucleating agents can increase the crystallization rate of polylactic acid and increase the degree of crystallinity. However, in recent years, more effective crystals have been developed to achieve higher moldability and heat resistance. Development of nucleating agents is desired.

JP-A-8-3432 Japanese Patent Laid-Open No. 10-87975 JP 2003-192894 A International Publication No. 05/099784 Pamphlet JP 2005-187630 A Japanese Patent Laying-Open No. 2005-255806 JP 2005-272679 A JP 2010-150365 A JP 2007-33264 A JP 2009-144056 A JP 2009-249615 A

In the above patent documents, a nucleating agent effective for promoting crystallization of polylactic acid of a stereocomplex having a melting point higher by several tens of degrees Celsius than poly-L-lactic acid and excellent in heat resistance has been reported. The effect of improving the temperature is not satisfactory, and it is still insufficient as a method for improving the molding processability and heat resistance of a large molded product.
An object of the present invention is to provide a polylactic acid resin composition having a high crystallization temperature and excellent molding processability and heat resistance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have achieved the above object, particularly preferably by melt-kneading and blending a hydrazide compound having a specific structure and a carbodiimide compound with polylactic acid. As a result, the present invention has been completed.

That is, the present invention
[1] A polylactic acid resin composition containing 90% by weight or more of polylactic acid, and in the DSC measurement in which one step of heating, holding and cooling in the following steps (1) to (3) is repeated three times, A polylactic acid resin composition having a crystallization temperature (peak top temperature: T _cd ) of 155 ° C. or higher in the first and third temperature lowering steps and a calorific value (H _c ) of 45 J / g or higher,
(1) Temperature rise from 30 ° C. to 260 ° C. at 20 ° C./min (2) Hold at 260 ° C. for 1 minute (3) Temperature drop from 260 ° C. to 30 ° C. at 20 ° C./min [2] Stereocomplex crystals The polylactic acid resin composition according to the above [1], which contains ~ 100%
[3] The polylactic acid resin composition of [1] and [2] above, which contains a hydrazide compound represented by the following formula (I) and a carbodiimide compound represented by the following formula (II):
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.)
[4] 100 parts by weight of a polylactic acid resin, 0.01 to 5 parts by weight of a hydrazide compound represented by the following formula (I), and 0.01 to 5 parts by weight of a carbodiimide compound represented by the following formula (II) A polylactic acid resin composition containing
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)

(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.)
[5] 100 parts by weight of polylactic acid, 0.01 to 5 parts by weight of a hydrazide compound represented by the following formula (I), and 0.01 to 5 parts by weight of a carbodiimide compound represented by the following formula (II) A method for producing a polylactic acid resin composition, characterized by melt-kneading,
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.)
[6] The method for producing a polylactic acid resin composition according to [5] above, wherein a hydrazide compound and a carbodiimide compound are simultaneously added to molten polylactic acid,
[7] The method for producing a polylactic acid resin composition according to the above [5], [6], wherein the polylactic acid is a blend of poly-L-lactic acid and poly-D-lactic acid,
[8] The method for producing a polylactic acid resin composition according to the above [5], [6], wherein the polylactic acid is a polylactic acid stereoblock copolymer,
[9] To 100 parts by weight of molten polylactic acid, 0.01 to 5 parts by weight of a hydrazide compound represented by the following formula (I) and 0.01 to 5 parts by weight of the following formula (II) A method for promoting crystallization of polylactic acid, comprising adding a carbodiimide compound;
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.)
Achieved by:

  According to the present invention, a polylactic acid resin composition having good crystallinity of polylactic acid and excellent in moldability and heat resistance can be provided, and the obtained polylactic acid resin composition is melt-molded. Thus, it is possible to obtain a molded body having high crystallinity containing polylactic acid. In particular, by blending polylactic acid with a specific structure of a hydrazide compound and a carbodiimide compound in a specific ratio, polylactic acid with further accelerated crystallization can be obtained. Such polylactic acid has improved crystallization speed and crystallinity, and thus has excellent heat resistance and good productivity such as injection molding.

2 is a chart of DSC measurement results of the polylactic acid resin composition obtained in Example 1. FIG.

The polylactic acid resin composition of the present invention will be described in detail below.
(Polylactic acid)
The polylactic acid used in the polylactic acid resin composition of the present invention is a polymer composed of lactic acid units represented by the following formula. The polylactic acid is preferably a blend (mixture) of poly-L-lactic acid and poly-D-lactic acid. Poly-L-lactic acid is a polymer mainly containing L lactic acid units, and poly-D-lactic acid is a polymer mainly containing D lactic acid units.
Here, “mainly” means that the repeating unit accounts for more than 50 mol% on the basis of all repeating units.

  The poly-L-lactic acid is preferably composed of 90 to 100 mol%, more preferably 95 to 100 mol%, and still more preferably 98 to 100 mol% L lactic acid units. Examples of other units include D lactic acid units and copolymer component units other than lactic acid.

  The D lactic acid unit and the copolymer component unit other than lactic acid are preferably 0 to 10 mol%, more preferably 0 to 5 mol%, and still more preferably 0 to 2 mol%. The poly-D-lactic acid is preferably composed of 90 to 100 mol%, more preferably 95 to 100 mol%, and still more preferably 98 to 100 mol% of D lactic acid units. Examples of other units include L lactic acid units and copolymer component units other than lactic acid. The L lactic acid unit and the copolymer component unit other than lactic acid are 0 to 10 mol%, preferably 0 to 5 mol%, more preferably 0 to 2 mol%.

  Poly-D-lactic acid is the same as poly-L-lactic acid, and the above description can be referred to. That is, it is preferably composed of 90 to 100 mol%, more preferably 95 to 100 mol%, and still more preferably 98 to 100 mol% of D lactic acid units. Examples of other units include L lactic acid units and copolymer component units other than lactic acid.

  Examples of copolymer component units include units derived from dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids and lactones having functional groups capable of forming two or more ester bonds, and various polyesters and various polyethers composed of these various components. And units derived from various polycarbonates.

  Examples of the dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid. Examples of the polyhydric alcohol include aliphatic polyhydrides such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, glycerin, sorbitan, neopentyl alcohol, diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol. Examples thereof include aromatic polyhydric alcohols such as alcohols or the like obtained by adding ethylene oxide to bisphenol. Examples of the hydroxycarboxylic acid include glycolic acid and hydroxybutyric acid. Examples of the lactone include glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone, and the like.

  The weight average molecular weight (Mw) of poly-L-lactic acid or poly-D-lactic acid is preferably 50,000 to 500,000, more preferably 150,000 to 350,000. Here, the weight average molecular weight is a weight average molecular weight in terms of standard polystyrene as measured by gel permeation chromatography (GPC) using chloroform as an eluent.

  Poly-L-lactic acid and poly-D-lactic acid can be produced by a known method. For example, it can be produced by heating and ring-opening polymerization of L-lactide or D-lactide in the presence of a metal polymerization catalyst. Moreover, after crystallizing low molecular weight polylactic acid containing a metal polymerization catalyst, it can be produced by solid phase polymerization by heating under reduced pressure or in an inert gas stream. Further, it can be produced by a direct polymerization method in which lactic acid is subjected to dehydration condensation in the presence / absence of an organic solvent.

  The polymerization reaction can be carried out in a conventionally known reaction vessel. For example, a vertical reaction vessel equipped with a high viscosity stirring blade such as a helical ribbon blade can be used alone or in parallel. Alcohol may be used as the polymerization initiator. Such alcohol is preferably non-volatile without inhibiting the polymerization of polylactic acid, for example, decanol, dodecanol, tetradecanol, hexadecanol, octadecanol, ethylene glycol, triethylene glycol, benzyl alcohol and the like are suitable. Can be used.

  The polylactic acid preferably contains stereocomplex crystals. Polylactic acid containing this stereocomplex crystal is called stereocomplex polylactic acid. A stereocomplex crystal is formed by mixing poly-L-lactic acid and poly-D-lactic acid. In this case, the weight ratio of poly-L-lactic acid to poly-D-lactic acid is preferably (90:10) to (10:90), more preferably (75:25) to (25:75), Preferably it is (60:40)-(40:60).

  The weight average molecular weight of the stereocomplex polylactic acid is preferably 100,000 to 500,000, more preferably 100,000 to 300,000. The weight average molecular weight is a weight average molecular weight in terms of standard polystyrene as measured by gel permeation chromatography (GPC) using chloroform as an eluent.

  The content of stereocomplex crystals is preferably 80 to 100%, more preferably 95 to 100%. The stereocomplex polylactic acid has a melting peak ratio of 195 ° C. or higher, preferably 80% or higher, more preferably 90% or higher, even more preferably, among melting peaks in the temperature rising process in differential scanning calorimetry (DSC) measurement. 95% or more. The melting point is preferably in the range of 195 ° C to 250 ° C, more preferably in the range of 200 ° C to 220 ° C.

Moreover, it is preferable that the value of the melting enthalpy derived from the melting peak in the temperature rising process is 20 J / g or more.
The amount of the carboxy terminus in stereocomplex polylactic acid was 12 eq. / Ton or less is preferred.

  Stereocomplex polylactic acid can be produced by mixing poly-L-lactic acid and poly-D-lactic acid at a predetermined weight ratio. Mixing can be performed in the presence of a solvent. The solvent is not particularly limited as long as it dissolves poly-L-lactic acid and poly-D-lactic acid. For example, chloroform, methylene chloride, dichloroethane, tetrachloroethane, phenol, tetrahydrofuran, N-methyl Preference is given to pyrrolidone, N, N-dimethylformamide, butyrolactone, trioxane, hexafluoroisopropyl alcohol or the like alone or in combination.

  Mixing can also be performed in the absence of a solvent. That is, a method of melt-kneading after mixing a predetermined amount of poly-L-lactic acid and poly-D-lactic acid, a method of melting and kneading one of them after melting one of them, and the like can be employed.

  When the resin composition of the present invention mixes poly-L-lactic acid and poly-D-lactic acid, for example, by melt kneading, the phosphoric acid ester metal salt represented by the following formulas (22) and (23) You may contain in 0.001-0.05 weight part on the basis of the total amount (100 weight part) of poly-L-lactic acid and poly-D-lactic acid.

In formula (22), R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ¹² and R ¹³ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, M ₁ represents an alkali metal atom, an alkaline earth metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, and q represents 0 when M ₁ is an alkali metal atom, an alkaline earth metal atom or a zinc atom. Represents an aluminum atom, 1 or 2.

In the formula (23), R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and M ₂ represents an alkali metal atom, an alkaline earth metal atom, a zinc atom or aluminum. P represents 1 or 2, q represents 0 when M2 is an alkali metal atom, alkaline earth metal atom, or zinc atom, and 1 or 2 when M2 is an aluminum atom.

M ₁ and M ₂ of the metal phosphate represented by the formula (22) or (23) are preferably Na, K, Al, Mg, Ca, Li, and in particular, Li, K, Na, Al, and Li. Al can be most preferably used.
As these metal phosphates, trade names manufactured by ADEKA Corporation, “ADEKA STAB” (registered trademark) NA-11, NA-21, NA-71 and the like can be preferably exemplified.

(Metal polymerization catalyst)
The composition of the present invention may contain a metal polymerization catalyst used when producing poly-L-lactic acid and poly-D-lactic acid. The metal polymerization catalyst is preferably a compound containing at least one metal element selected from the group consisting of alkaline earth metals, rare earth metals, fourth-period transition metals, aluminum, zinc, germanium, tin, and antimony. Examples of alkaline earth metals include magnesium, calcium, and strontium. Examples of rare earth elements include scandium and yttrium. Examples of the transition metal in the fourth period include iron, cobalt, nickel, and the like.
The metal polymerization catalyst can be added to the composition, for example, as a carboxylate, alkoxide, aryloxide, or β-diketone enolate of these metals.

  In view of polymerization activity and hue, tin octylate, titanium tetraisopropoxide, and aluminum triisopropoxide are particularly preferable. The content of the metal polymerization catalyst is preferably 0.001 to 0.1 parts by weight, more preferably 0.005 to 0.05 parts by weight with respect to 100 parts by weight of polylactic acid. In particular, if the content of the metal polymerization catalyst in the resin composition is too large, coloring due to reaction heat, or depolymerization or transesterification reaction is accelerated, so that the hue and thermal stability of the resulting composition tend to deteriorate. is there.

(Specific compounds)
The polylactic acid resin composition of the present invention is obtained by blending a hydrazide compound represented by the following formula (I) and a carbodiimide compound represented by the following formula (II) into the polylactic acid resin. .

(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)

(In the formula, Ar ¹ , Ar ² , Ar ³ and Ar ⁴ are each independently an alkyl group having 1 to 6 carbon atoms or an aromatic group having 6 to 20 carbon atoms.)

<Hydrazide compound>
In the above formula (I), R ¹ , R ² , R ³ , and R ⁴ may each independently be substituted with an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 12 carbon atoms. .
The alkyl group may have a branch, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, secondary butyl group, tertiary butyl group, isobutyl group, amyl group, isoamyl group, tertiary group. Amyl group, hexyl group, 2-hexyl group, 3-hexyl group, heptyl group, 2-heptyl group, 3-heptyl group, isoheptyl group, tertiary heptyl group, n-octyl group, isooctyl group, tertiary octyl group, Examples include 2-ethylhexyl group, nonyl group, isononyl group, dodecyl group and the like. Examples of the aryl group include a phenyl group and a naphthalenyl group.

Specifically preferred as the compound represented by the above formula (I) is terephthalic acid dihydrazide in which R ^{1 to} R ⁴ are all hydrogen atoms.
Content of the hydrazide compound in a polylactic acid resin composition is 0.01-5 weight part with respect to 100 weight part of polylactic acid, Preferably it is 0.2-2.0 weight part, More preferably, it is 0.25. -1.0 part by weight. When the amount is less than 0.01 part by weight, the effect of promoting crystallization of polylactic acid is insufficient, and when the amount is more than 5 parts by weight, the production cost of the molded product may be affected.

<Carbodiimide compound>
In the above formula (II), Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently independently substituted with an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. 6-20 aromatic groups. Examples of the aromatic group having 6 to 20 carbon atoms include a phenylene group and a naphthalenediyl group. Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, tertiary butyl, isobutyl, amyl, isoamyl, A triamyl group, a hexyl group, a 2-hexyl group, and a 3-hexyl group may be mentioned.

The content of the carbodiimide compound in the polylactic acid resin composition is 0.01 to 5 parts by weight, preferably 0.4 to 4.0 parts by weight, and more preferably 0.4 to 100 parts by weight of the polylactic acid resin. -2.7 parts by weight. If the amount is less than 0.01 parts by weight, the effect of addition is insufficient. If the amount is more than 5 parts by weight, a phenomenon such as a carbodiimide compound bleeding out on the surface of the polylactic acid resin composition occurs, and the appearance of the molded product Further, the molecular weight and content of the hydrazide compound represented by the above formula (I) may be M ₁ , x parts by weight, respectively, and the molecular weight and content of the carbodiimide compound represented by the above formula (II). The mixing ratio of these two agents (molar ratio: (y / M ₂ ) / (x / M ₁ )) when M ₂ and y parts by weight are 0.37 to 2.7, respectively. Preferably, it is 0.6 to 1.2.
When the value of this molar ratio exceeds 3.3, a sufficient nucleating agent effect may not be obtained even if the blending amount of the hydrazide compound and the carbodiimide compound is within the range of the above preferred values.

As the carbodiimide compound represented by the above formula (II), specifically, a compound represented by the following formula (II) -a in which all of Ar ^{1 to} Ar ⁴ are represented by ortho disubstituted benzene rings. Is preferred.

  Such a carbodiimide compound can be easily produced by referring to the production examples of the international publication WO2010 / 071213 pamphlet.

  In addition, as long as it does not impair the effects of the present invention, conventionally known plasticizers, antioxidants, heat stabilizers, hydrolysis inhibitors, light stabilizers, ultraviolet absorbers, pigments, and colorants, if necessary. Various fillers, antistatic agents, mold release agents, fragrances, lubricants, flame retardants, silicic acid based inorganic additives, foaming agents, fillers, antibacterial agents, antifungal agents, and the above formulas (I) and (II) You may mix | blend various additives, such as crystal nucleating agents other than the compound represented. The content of such additives is preferably 20% by weight or less in the polylactic acid resin composition of the present invention.

In the polylactic acid resin composition of the present invention, a method of blending two components of the hydrazide compound and the carbodiimide compound represented by the above formulas (I) and (II) into the polylactic acid resin is performed by a conventionally known melt-kneading method. be able to.
For example, the polylactic acid resin and the additive can be mixed by dry blending and then melt kneaded with a single screw or twin screw extruder. Alternatively, the additive may be directly added to the polylactic acid resin melted in a kneader using an automatic powder addition apparatus such as a disk feeder, and melt kneading may be performed.

  Since the melting point of the stereocomplex crystal of polylactic acid is 200 ° C. or higher, the melt kneading can usually be carried out in the range of 230 ° C. to 250 ° C. It is particularly preferable to knead the two agents simultaneously with the melted polylactic acid in order to develop a high crystallization promoting effect. First, one agent is added and kneaded, and then the other agent is added and kneaded. The blending method may not provide a sufficient crystallization promoting effect. Moreover, a sufficient crystallization promoting effect cannot be obtained only by blending only one of the agents into polylactic acid.

  The stereocomplex polylactic acid resin obtained by the present invention is used in various molding methods, for example, an injection molded product, an extrusion molded product, a vacuum / pressure molded product, a blow molded product, a film, a sheet nonwoven fabric, a fiber, a cloth, and other materials. And composites, agricultural materials, fishery materials, civil engineering / architectural materials, stationery, medical supplies or other molded products can be obtained, and molding can be carried out by conventional methods.

  ADVANTAGE OF THE INVENTION According to this invention, the polylactic acid resin composition by which the crystallization of polylactic acid was further accelerated | stimulated by mix | blending the hydrazide compound and carbodiimide compound of a specific structure with a specific ratio with polylactic acid is provided. The polylactic acid resin composition of the present invention includes, for example, aromatic polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, aliphatic polyesters such as polybutylene succinate (PBS) and polyhydroxybutyrate (PHB), PMMA It can be used by mixing with other thermoplastic resins such as acrylic resins such as polyol resins, polyolefin resins such as polypropylene and polyethylene, ABS resins, polycarbonates and polyamides.

  In addition, the crystal | crystallization promotion effect of the hydrazide compound and carbodiimide compound with respect to the stereocomplex polylactic acid in this invention can be evaluated by the following DSC measurement, for example.

That is, first, a part (5 to 10 mg) of a sample (stereo complex polylactic acid resin composition) was subjected to the following series of (1) to (3).
(1) Heat from 30 ° C. to 260 ° C. by “heating” at a rate of temperature increase of 20 ° C./min,
(2) After “hold” at 260 ° C. for 1 minute to melt,
(3) Cool by “falling down” from 260 ° C. to 30 ° C. at a cooling rate of 20 ° C./min.
The process of performing each step in turn is made into one cycle for a total of 3 cycles. The crystallization temperature (crystallization peak temperature) of the stereocomplex polylactic acid in the first and third cycles and the calorific value based on crystallization (crystallization enthalpy) ) An example of a chart obtained by DSC measurement is shown in FIG. 1 (corresponding to Example 1 described later).

In FIG. 1, as the crystallization temperature (peak top temperature: hereinafter referred to as T _cd ) in the cooling process (temperature measurement) of the above (3) is observed on the higher temperature side, the crystallization rate becomes higher. The larger the calorific value based on crystallization in the cooling process (crystallization enthalpy: hereinafter referred to as ΔH _c ), the higher the crystallinity improvement effect. In a large molded body, since the resin may stay in the molding machine for several tens of minutes at a temperature equal to or higher than the melting point of the resin, the values of T _cd and ΔH _c in the DSC measurement are as described in (1) to (3) above. Not only the value of the first cycle but also the value of the third cycle when the cycle is continuously repeated (the value when the resin receives a large amount of thermal history) can be maintained sufficiently large (T _cd is 155 ° C. or higher) , H _c is 45 J / g or more) is important in enhancing the moldability and heat resistance of the stereocomplex polylactic acid resin.

[Action]
In the present invention, when two agents having a specific structure (the hydrazide compound and carbodiimide compound) are simultaneously melt-kneaded in polylactic acid, a particularly high crystallization promoting effect is obtained. It is inferred that the product (the polycondensation product because it is bifunctional with each other) or the reaction product of these two agents with polylactic acid exhibits a high crystallization promoting effect (nucleating agent effect).

In fact, it is known from the IR measurement of the resin after blending the two agents that the carbodiimide compound may be completely consumed when the blending amount of the hydrazide compound is increased. It has been suggested to react. Although it is not certain what type of product is formed after blending the two agents, it is known that the carboxy terminus of polylactic acid reacts with the carbodiimide compound, and the hydrazide terminus —NH ₂ Considering that the group is nucleophilic and can react with polylactic acid, these two agents may react with polylactic acid in multiple stages to give a product represented by the following formula. The inventors are thinking.

(The structural formula of the presumed product when combining two particularly suitable agents is shown above. (Wavy line) in the above formula represents the main chain of polylactic acid. Also, the carbodiimide at the upper end. The carbodiimide group at the lower end may be reacted in the same manner as the group, or it may be a star-shaped product having four polylactic acid main chains in one molecule.
(1) the structure represented by the above formula (III) is bonded to polylactic acid, and
(2) The stereocomplex polylactic acid is crystallized by two points that the main chain of polylactic acid is easily entangled with each other by becoming a molecule having a maximum of four polylactic acid main chains in one molecule. I guess it was promoted.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.
In addition, as DSC measurement results (values of T _cd and ΔH _c in Tables 1 to 5) of samples in the following examples and comparative examples, 1 under the conditions described in (1) to (3) above. Both the value of the 1st cycle and the value of the 3rd cycle (3rdcycle) are shown.

[Reference Example 1] Synthesis example of homopolylactic acid by melt ring-opening polymerization of lactide:
A vertical stirring tank (250 L) equipped with an anchor blade equipped with a vacuum pipe, nitrogen gas pipe, catalyst, L-lactide addition pipe, and alcohol initiator addition pipe was purged with nitrogen, and then charged with L-lactide 60 kg to 140 ° C. The mixture was stirred and melted while heating.
This molten lactide is fed to a full-zone blade equipped stirring tank (120 L), stearyl alcohol 0.20 kg (0.012 mol / kg), and tin octylate 1.80 g (7.4 × 10 ⁻⁵ mol / kg). Was heated to 150 ° C. in a nitrogen gas atmosphere. Stirring was started when the contents were dissolved, and the internal temperature was raised from 185 ° C. to 190 ° C. and held.

The viscosity of the reaction mixture increased with the progress of the reaction, and the power required for stirring gradually improved. Stirring was continued until this power value was saturated (several hours). After the stirring was stopped, the reaction vessel was degassed for 30 minutes at 39.9 kPa (300 Torr) and then allowed to stand, and the internal pressure was increased to 0.2 to 0.3 MPa (2 to 3 atmospheres) with nitrogen pressure. The polymer was extruded into a chip cutter and pelletized. Further, the pellets are melted with an extruder, charged into a non-axial vertical reactor at 30 kg / hr, depressurized to 1.5 kPa, and the residual lactide is reduced, and then the pellets are converted into chips again. -L-lactic acid has a weight average molecular weight of 160,000, polydispersity of 2.2, lactide content of 0.1 wt%, melting point of 179 ° C., carboxyl terminal amount of 6 eq. / Ton.
The same operation was performed except that D-lactide was used instead of L-lactide as a starting material, and the weight average molecular weight 150,000, polydispersity 2.1, lactide content 0.1 wt%, melting point 177 ° C, carboxyl end group amount 8 eq. / Ton poly-D-lactic acid was obtained.

[Reference Example 2] Synthesis example of stereocomplex polylactic acid by melt-kneading poly-L-lactic acid and poly-D-lactic acid:
The poly-L-lactic acid and poly-D-lactic acid chips produced in Reference Example 1 were mixed at a weight ratio of 1: 1, and dried at 50 ° C. for 5 hours in a dehumidifying dryer. After mixing 0.03 wt% of “Adekastab (registered trademark)” NA-11 (manufactured by ADEKA Corporation), which is a phosphate metal salt, with 100 parts by weight of the mixed chip, a twin-screw extruder at 270 ° C. The mixture was melt kneaded and extruded onto a chip cutter to obtain polylactic acid chips. As a result of DSC measurement of this chip, no crystal melting peak derived from homopolylactic acid was observed, and it was a stereocomplex polylactic acid having a melting point of 220 ° C. The weight average molecular weight was 130,000, the polydispersity was 2.1, and the carboxyl end group amount was 11 eq. / Ton.

  In the following Examples and Reference Examples, various additives (nucleating agents) are melt kneaded at 230 ° C. and rpm = 30 with 10.0 g of stereocomplex polylactic acid prepared as described above using a lab plast mill. A sample was prepared.

The following methods (A1), (A2), (B), (C), (D), and (E) are used as methods for adding and kneading hydrazide compounds (hereinafter sometimes referred to as additives) and carbodiimide compounds. Either one was adopted. That is, for 100 parts by weight of stereocomplex polylactic acid melted at 230 ° C.
(A1) Add only x parts by weight of additive and knead for 3 minutes,
(A2) Only x parts by weight of the additive was first added and kneaded for 3 minutes, immediately after that y parts by weight of the carbodiimide compound was added, and kneaded for another 90 seconds.
(B) x parts by weight of additive and y parts by weight of carbodiimide compound are simultaneously added and kneaded for 3 minutes,
(C) x parts by weight of additive and y1 parts by weight of carbodiimide compound were added simultaneously and kneaded for 3 minutes, immediately after that y2 parts by weight of carbodiimide compound was added, and kneaded for 90 seconds.
(D) Only y parts by weight of the carbodiimide compound is first added and kneaded for 90 seconds, immediately after that x parts by weight of the additive is added, and further kneaded for 3 minutes.
(E) Only y1 part by weight of the carbodiimide compound is first added and kneaded for 90 seconds. Immediately thereafter, only x parts by weight of the additive is added and kneaded for 3 minutes. Of carbodiimide compound, kneading for 90 seconds,
A kneaded sample of the additive was prepared by either of the above.

However, only Example 7, Example 8, and Comparative Example 31 were kneaded under the following kneading conditions (B ′) using a twin screw extruder instead of a lab plast mill as a kneading machine. That is,
(B ′) A mixture of these two components is disc feeder so that the amount of additive contained is x parts by weight and the amount of carbodiimide compound contained is y parts by weight with respect to 100 parts by weight of stereocomplex polylactic acid. Were simultaneously added by a twin-screw extruder, and a sample was prepared by kneading the polylactic acid melt at 230 ° C. and rpm = 30 (average residence time was about 3 minutes).

In Comparative Examples 37 and 38, kneaded samples were prepared using homopoly-L-lactic acid instead of stereocomplex polylactic acid. Since homopoly-L-lactic acid has a melting point lower than that of stereocomplex polylactic acid by about 40 ° C., only Comparative Examples 37 and 38 were measured under the following conditions with the maximum temperature rise in DSC measurement set lower. . That is, each of the following steps (1) to (3) is continuously performed, and this is regarded as one cycle, and each of the steps (1) to (3) is continuously performed for three cycles, and the temperature is increased, maintained, and DSC measurement was performed by repeating the temperature drop.
(1) Temperature increase rate from 30 ° C. to 215 ° C. at 20 ° C./min. The temperature rises.
(2) Hold at 215 ° C. for 1 minute.
(3) Temperature drop rate from 215 ° C. to 30 ° C. 20 ° C./min. Decrease in temperature.

[Reference Example 3] Synthesis of carbodiimide compound:
The following operations were performed according to the description of International Publication No. 2010/072111 pamphlet and Example 2.
o- nitrophenol (0.11 mol) and pentaerythrityl tetra bromide (0.025 mol), potassium carbonate (0.33mol), N, N- dimethylformamide 200ml in reactor installed with a stirrer and a heating device _{N 2} After charging in an atmosphere and reacting at 130 ° C. for 12 hours, DMF was removed under reduced pressure, and the resulting solid was dissolved in 200 ml of dichloromethane and separated three times with 100 ml of water. The organic layer was dehydrated with 5 g of sodium sulfate, and dichloromethane was removed under reduced pressure to obtain an intermediate product (nitro form).

Next, an intermediate product (nitro compound) (0.1 mol), 5% palladium carbon (Pd / C) (2 g), and 400 ml of ethanol / dichloromethane (70/30) were charged into a reactor equipped with a stirrer. Hydrogen substitution was performed 5 times, and the reaction was carried out in a state where hydrogen was constantly supplied at 25 ° C., and the reaction was terminated when the decrease in hydrogen was stopped, Pd / C was recovered, the mixed solvent was removed, and an intermediate product (amine) Body).
Subsequently, in a reactor equipped with a stirrer, a heating device, and a dropping funnel, triphenylphosphine dibromide (0.11 mol) and 150 ml of 1,2-dichloroethane were charged and stirred in an N ₂ atmosphere, while the intermediate product was stirred. A solution prepared by dissolving (amine body) (0.025 mol) and triethylamine (0.25 mol) in 50 ml of 1,2-dichloroethane was gradually added dropwise at 25 ° C. After the completion of the addition, the mixture was reacted at 70 ° C. for 5 hours.

Thereafter, the reaction solution was filtered, and the filtrate was separated 5 times with 100 ml of water. The organic layer was dehydrated with 5 g of sodium sulfate, and 1,2-dichloroethane was removed under reduced pressure to obtain an intermediate product (triphenylphosphine compound).
Furthermore, in a reactor equipped with a stirrer and a dropping funnel, di-tert-butyl dicarbonate (0.11 mol), N, N-dimethyl-4-aminopyridine (0.055 mol), dichloromethane 150 ml under N ₂ atmosphere. Were stirred. Thereto, 100 ml of dichloromethane in which an intermediate product (triphenylphosphine compound) (0.025 mol) was dissolved was slowly added dropwise at 25 ° C., followed by reaction for 12 hours. Then, the carbodiimide compound shown by following formula (II) -a was obtained by refine | purifying the solid substance obtained by removing dichloromethane.

[Example 1]
1.0 part by weight of a terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following formula as an additive, and 1.0 part by weight of a carbodiimide compound obtained by the operation of Reference Example 3 as a carbodiimide compound, A sample was prepared by blending with 100 parts by weight of the polylactic acid of Reference Example 2 by the kneading method (A2). The DSC measurement results of the obtained kneaded sample are shown in FIG.

[Example 2]
Kneading method (A2) using 1.0 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 2.7 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound. A sample was prepared by The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 3]
Kneading method (A2) using 1.0 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 4.0 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound. A sample was prepared by The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 4]
Kneading method (A2) using 0.75 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.0 part by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound. A sample was prepared by The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 5]
A sample was prepared by kneading method (A2) using 0.50 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.0 part by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound. Prepared. The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 6]
Using 0.20 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.8 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 7]
Using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 0.8 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, kneading method B ′ (two Samples were prepared by a screw extruder. The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 8]
Using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 0.4 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, kneading method B ′ (two Samples were prepared by a screw extruder. The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Example 9]
First, 0.25 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.8 part by weight of carbodiimide synthesized by the operation of Reference Example 3 were simultaneously kneaded into polylactic acid as an additive. A sample was prepared by a kneading method (C) in which 1.5 parts by weight of additional carbodiimide synthesized by the operation of Reference Example 3 was further kneaded. The DSC measurement results of the obtained kneaded sample are shown in Table 1.

[Comparative Example 1]
As a control, a sample was obtained by kneading the stereocomplex polylactic acid obtained in Reference Example 2 for 3 minutes at 230 ° C. and rpm = 30 without adding any additives. The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 2]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of the compound represented by the formula (II) -a as an additive. Table 2 shows the DSC measurement results of the obtained sample.

[Comparative Example 3]
By using 1.0 part by weight of “Eco Promote (registered trademark)” NP (manufactured by Nissan Chemical Industries, Ltd .: zinc phenylphosphonate) instead of the above additive, kneading method (A1) Samples were prepared. Table 2 shows the DSC measurement results of the obtained sample.

[Comparative Example 4]
Instead of the additive, 1.0 part by weight of “Eco Promote (registered trademark)” NP (Nissan Chemical Industries, Ltd .: zinc phenylphosphonate) was represented by the above formula (II) -a as a carbodiimide compound. A sample was prepared by a kneading method (A2) using 1.0 part by weight of the compound. The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 5]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of copper phthalocyanine instead of the additive. The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 6]
A sample was prepared by a kneading method (A2) using 1.0 part by weight of copper phthalocyanine instead of the additive and 1.0 part by weight of the compound represented by the formula (II) -a as a carbodiimide compound. The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 7]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of sodium benzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of the additive. The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 8]
Instead of the above additives, 1.0 part by weight of sodium benzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.0 part by weight of the compound represented by the above formula (II) -a as a carbodiimide compound, A sample was prepared by the kneading method (A2). The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 9]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of MC-6000 (manufactured by Nissan Chemical Industries, Ltd .: melamine cyanurate) instead of the additive. The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 10]
1.0 part by weight of the compound represented by the above formula (II) -a as a carbodiimide compound was used as 1.0 part by weight of MC-6000 (manufactured by Nissan Chemical Industries, Ltd .: melamine cyanurate) instead of the above additive. A sample was prepared using the kneading method (A2). The DSC measurement results of the obtained kneaded sample are shown in Table 2.

[Comparative Example 11]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of terephthalic acid dihydrazide instead of the additive. Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 12]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of isophthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of the additive. Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 13]
Kneading 1.0 part by weight of isophthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of the above additive using 1.0 part by weight of the compound represented by the above formula (II) -a as a carbodiimide compound Samples were prepared by method (A2). Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 14]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of phthalic acid hydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of the additive. Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 15]
Kneading 1.0 part by weight of phthalic acid hydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of the above additive using 1.0 part by weight of the compound represented by the above formula (II) -a as a carbodiimide compound Samples were prepared by method (A2). Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 16]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of dodecanedioic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of the additive. Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 17]
Instead of the additive, 1.0 part by weight of dodecanedioic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) is used as the carbodiimide compound, and 1.0 part by weight of the compound represented by the above formula (II) -a, A sample was prepared by the kneading method (A2). Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 18]
A sample was prepared by a kneading method (A1) using 1.0 part by weight of a sulfonylhydrazine-based compound (N, N′-bis (p-toluenesulfonyl) hydrazine: manufactured by Aldrich) instead of the additive. Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 19]
Instead of the additive, 1.0 part by weight of a sulfonylhydrazine compound (N, N′-bis (p-toluenesulfonyl) hydrazine: manufactured by Aldrich) was represented by the above formula (II) -a as a carbodiimide compound. A sample was prepared by a kneading method (A2) using 1.0 part by weight of the compound. Table 3 shows the DSC measurement result of the obtained sample.

[Comparative Example 20]
By using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.0 part by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (A2) Samples were prepared. Table 3 shows the DSC measurement results of the obtained kneaded sample.

[Comparative Example 21]
By using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.8 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (A2) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 22]
Using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.8 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 23]
Using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 2.3 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 24]
Using 0.15 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 1.8 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 25]
Using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 0.4 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 26]
By using 0.25 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 0.25 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 27]
Using 0.50 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 0.4 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 28]
Using 1.58 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 0.4 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, respectively, by kneading method (B) Samples were prepared. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 29]
First, 0.20 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.4 part by weight of carbodiimide synthesized by the operation of Reference Example 3 were simultaneously kneaded into polylactic acid as an additive. A sample was prepared by a kneading method (C) in which 1.4 parts by weight of additional carbodiimide synthesized by the operation of Reference Example 3 was further kneaded. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 30]
First, 0.15 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.48 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 were simultaneously kneaded into polylactic acid as an additive. A sample was prepared by a kneading method (C) in which 1.32 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 was further kneaded. Table 4 shows the results of DSC measurement of the obtained kneaded sample.

[Comparative Example 31]
Using 1.58 parts by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) as an additive and 5.06 parts by weight of carbodiimide synthesized by the operation of Reference Example 3 as a carbodiimide compound, kneading method B ′ (two Samples were prepared by a screw extruder. Table 5 shows the DSC measurement results of the obtained kneaded sample.

[Comparative Example 32]
First, only 0.40 part by weight of carbodiimide synthesized by the operation of Reference Example 3 is kneaded, and then 0.20 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) is kneaded (D) A sample was prepared by Table 5 shows the DSC measurement results of the obtained kneaded sample.

[Comparative Example 33]
First, only 0.40 part by weight of carbodiimide synthesized by the operation of Reference Example 3 was kneaded, and then 0.20 part by weight of terephthalic acid dihydrazide (manufactured by Tokyo Chemical Industry Co., Ltd.) was kneaded. A sample was prepared by a kneading method (E) in which 1.40 parts by weight of carbodiimide synthesized by the operation 3 was additionally kneaded. Table 5 shows the DSC measurement results of the obtained kneaded sample.

[Comparative Example 34]
As a carbodiimide compound, 0.25 part by weight of terephthalic acid dihydrazide was added as “STABAXOL (registered trademark)” I-LF (manufactured by Rhein Chemie: N, N′-di-2,6-diisopropylbenzenecarbodiimide). A sample was prepared by kneading method (B) using 56 parts by weight. Table 5 shows the DSC measurement result of the obtained sample.

[Comparative Example 35]
As a carbodiimide compound, 0.25 part by weight of terephthalic acid dihydrazide is 0.39 wt. Of “Carbodilite (registered trademark)” LA-1 (Nisshinbo Chemical Co., Ltd .: poly- (4,4′-dicyclohexylmethanecarbodiimide)). A sample was prepared by the kneading method (B). Table 5 shows the DSC measurement result of the obtained sample.

[Comparative Example 36]
A sample was prepared by kneading method (B) using 0.25 parts by weight of terephthalic acid dihydrazide as a carbodiimide compound and 0.39 parts by weight of the following formula (II) -b (refer to WO2010 / 072111 for the production method). . Table 5 shows the DSC measurement result of the obtained sample.

[Comparative Example 37]
DSC measurement was performed using the poly-L-lactic acid synthesized in Reference Example 1 as it was. The measurement results are shown in Table 5.

[Comparative Example 38]
A poly-L-lactic acid kneaded sample was prepared by kneading method (B) using 0.25 parts by weight of terephthalic acid dihydrazide as a carbodiimide compound and 0.40 parts by weight of the compound represented by formula (II) -a. did. Table 5 shows the DSC measurement result of the obtained sample.

Comparative Examples 1 to 38 summarize the results of comparative studies on various nucleating agents that are said to promote crystallization of polylactic acid.
Under the conditions in which no carbodiimide compound was added (Comparative Examples 3, 5, 7, 9, 11), the best results were obtained in the first cycle of the DSC “Eco Promote®” NP (Comparative Example 3: T _cd = 160 ° C., ΔH _c = 49 J / g) However, polylactic acid containing this agent has poor thermal stability, and in the third cycle of DSC, it decreased to T _cd = 146 ° C. and ΔH _c = 41 J / g. I have.

Moreover, in the conditions (Comparative Examples 4, 6, 8, and 10) in which the carbodiimide compound represented by the above formula (II) -a is also kneaded, both the values of T _cd and ΔH _c are compared with the case where the carbodiimide compound is not added. MC-6000 (Comparative Example 10), which was found to be smaller and gave the best results in the first cycle of DSC, showed only a nucleating agent effect of T _cd = 146 ° C. and ΔH _c = 53 J / g. .

On the other hand, when terephthalic acid dihydrazide is used as a nucleating agent, unlike the above comparative example, the values of T _cd and ΔH _c are improved by kneading the carbodiimide compound represented by the formula (II) -a. (Comparative Example 11 and Example 1), T _cd = 161 ° C. and ΔH _c = 51 J / g were maintained even in the third cycle of DSC, and remarkable crystallization not found in conventional nucleating agents It was found that a promoting effect was exhibited.

  In Comparative Examples 11 to 19, the results of comparative studies on hydrazide compounds other than terephthalic acid dihydrazide are summarized. Under the conditions where the carbodiimide compound represented by the above formula (II) -a is not added, isophthalic acid dihydrazide (Comparative Example 12), which is an isomer of terephthalic acid dihydrazide, and phthalic acid hydrazide (Comparative Example), which is a cyclic condensed ring compound of an isomer 14) Dodecanedioic acid dihydrazide which is an aliphatic hydrazide compound (Comparative Example 16), N, N′-bis (p-toluenesulfonyl) hydrazine having a sulfonyl group instead of an acyl group as a substituent on the nitrogen atom ( It was found that all of Comparative Examples 18) showed a certain nucleating agent effect.

However, in all cases, the nucleating agent effect was low, and it was found that when the carbodiimide compound represented by the above formula (II) -a was also kneaded, the values of T _cd and ΔH _c were lowered in any case (comparison) Examples 13, 15, 17, 19).
From the above, it was found that when terephthalic acid dihydrazide is specifically used with respect to the carbodiimide represented by the above formula (II) -a, a high nucleating agent effect is exhibited when two agents are used in combination.

  In Comparative Examples 20 to 33 and Examples 1 to 9, the results of examining the addition amount and the addition method of terephthalic acid dihydrazide and the carbodiimide compound represented by the above formula (II) -a are summarized. First, kneading method A2, in which only terephthalic acid dihydrazide is kneaded for 3 minutes, and immediately after that kneading carbodiimide compound, two components were added and kneaded in various amounts, and it was found that good nucleating agent effect was shown. (Example 1-5: The weight ratio of the added amount of the two agents is 1: 1 to 1: 4, and the molar ratio is 1: 0.38 to 1: 1.50). On the other hand, in the kneading method A2, it was found that when the amount of terephthalic acid dihydrazide added was reduced to 0.25 parts by weight, a sufficient nucleating agent effect was not exhibited (Comparative Example 20). When the amount of carbodiimide groups contained in the sample obtained in Example 1 was estimated by IR measurement, a sufficient amount of carbodiimide groups remained in Comparative Example 2, whereas in the sample of Example 1, the above-mentioned No peak derived from the carbodiimide group represented by the formula (II) -a was observed, suggesting that this carbodiimide compound reacts with terephthalic acid dihydrazide.

As described above, it is considered that the product formed by the reaction of these two agents, or the product formed by the reaction of these two agents with polylactic acid exhibits a high nucleating agent effect. Then, next, the addition amount was examined for kneading method B (kneading with a lab plast mill) and B ′ (kneading with a twin screw extruder) in which these two agents were added and kneaded simultaneously. When the amount of terephthalic acid dihydrazide to be added is fixed to 0.25 parts by weight, the amount of the carbodiimide compound represented by the formula (II) -a is 1.8 parts by weight or 0.4 parts by weight (Comparative Example 22 and 25) were found to give a high T _cd of 160 ° C. or higher in the first DSC cycle. The weight ratio is 1: 7.2 and 1: 1.6, and the molar ratio is 1: 2.7 and 1: 0.6. When the addition amount of the carbodiimide compound to be added is further reduced to 0.25 parts by weight, it is presumed that these two agents simply do not easily react and do not exhibit a sufficient nucleating agent effect (Comparative Example 26). It was also found that a sufficient nucleating agent effect could not be obtained even if the amount of carbodiimide compound added was increased too much (Comparative Example 23). When the carbodiimide compound represented by the above formula (II) -a is added at a high concentration, it is presumed that the equilibrium process of polymerization / depolymerization between these carbodiimide compounds will compete, and instead react with terephthalic acid dihydrazide. I think it will be difficult. When the amount of the carbodiimide compound added in the kneading method A2 is increased from 1.0 part by weight to 1.8 parts by weight (Comparative Examples 20 and 21), the reason why the nucleating agent effect cannot be obtained is largely due to the same reason. thinking. In addition, in kneading method A2, when only terephthalic acid dihydrazide is first kneaded, it is expected that polylactic acid and hydrazide compound will react to some extent. This is considered to be a disadvantageous kneading method. Actually, when the addition amount of the hydrazide compound and the addition amount of the carbodiimide compound are the same, the kneading method B (Comparative Example 22) in which these two agents are simultaneously added and kneaded is more than the kneading method A2 (Comparative Example 21). , It was found to be excellent in exhibiting a high nucleating agent effect.

Also, the kneading method is unified to B which is added and kneaded at the same time, the amount of carbodiimide compound added is fixed at 1.8 parts by weight, and the amount of terephthalic acid dihydrazide added is from 0.25 parts by weight to 0.2 parts by weight. When the amount was reduced to 15 parts by weight (Comparative Example 22, Example 6, Comparative Example 24), it was found that the values of T _cd and ΔH _c decreased as the amount of hydrazide added decreased. Again, it was suggested that in order to efficiently react these two agents, it is necessary to add a certain amount of hydrazide compound.

On the other hand, the kneading method was unified to B, the amount of carbodiimide compound added was fixed at 0.4 parts by weight, and the amount of terephthalic acid dihydrazide added was increased from 0.25 to 1.58 parts by weight. However (Comparative Examples 25, 27, and 28), on the other hand, it was found that the values of T _cd and ΔH _c were lowered, and in order to efficiently provide a reaction product that promotes crystallization, only the addition amount of the two components to be added was required. In addition, it was suggested that the addition amount ratio (molar ratio) is also important.

Further, it was found that a good crystallization promoting effect can be obtained even if a twin screw extruder is used as a kneading machine instead of a lab plast mill (Example 7), and the amount of carbodiimide compound added is reduced to 0.40 parts by weight. The best nucleating agent effect was obtained (Example 8).
The reason why the twin-screw extruder gave better results when comparing Example 8 and Comparative Example 25 is considered to be because the stirring efficiency is better when the twin-screw extruder is used.
That is, if a twin-screw extruder is used, kneading can be started continuously from the moment the two components are charged into the kneader, and the stirring efficiency and the reaction efficiency between the hydrazide and the carbodiimide compound are improved accordingly. It is considered a thing.

  As shown in Example 9, a kneading method in which a hydrazide compound and a small amount of a carbodiimide compound are first kneaded and then a carbodiimide compound is additionally kneaded so as to impart sufficient heat and heat resistance to polylactic acid. It was found that C also shows a good nucleating agent effect. Further, from the comparison between Example 9 and Comparative Example 22, even when the total amount of the carbodiimide compound finally blended is the same, the smaller the amount of the carbodiimide compound added together with the hydrazide compound, the better the crystallization promoting effect. It can be said that it develops. Also in this kneading method C, it can be seen that when the amount of hydrazide compound used is less than 0.20 parts by weight, the nucleating agent effect is reduced (Comparative Examples 29 and 30), and a good nucleating agent effect is exhibited. Therefore, it can be said that the addition of about 0.25 parts by weight of a hydrazide compound is necessary.

Using the sample obtained in Comparative Example 29, (1) 50 ° C./min. (2) held at 250 ° C. for 5 minutes, and (3) from 250 ° C. to 30 ° C. at 5 ° C./min. In that cooling, was subjected to DSC measurement by changing the measurement conditions DSC described in Patent Document _3, T cd = 172 _℃, results in ΔH _c = 55J / g was obtained. It is natural that the value of T _cd is improved if the temperature is slowly lowered, and generally, the crystallinity is also improved if the temperature is slowly cooled, so it is no wonder that the value of ΔH _c is improved. .

The DSC measurement result in the example (a polylactic acid resin composition containing 0.5 part by weight of a phosphoric acid ester metal salt and 1.0 part by weight of talc) described in Patent Document 3 is T _cd = 171 ° C., ΔH _c = 58 J / g, 20 ° C./min. Although it is difficult to make a direct comparison at such a high temperature-decreasing rate, it is considered that even a nucleating agent that was conventionally effective for crystallization of stereocomplex polylactic acid was equivalent to Comparative Example 20.
In the present invention, 20 ° C./min. A high T _cd of 170 ° C. or higher can be realized even at a high temperature drop rate, and the value of ΔH _c is as high as 52 J / g, which makes it difficult for conventional nucleating agents to produce large injection molded products using stereocomplex polylactic acid resin. Can also be provided.

  Even in the case of two-component simultaneous kneading using a twin-screw extruder (kneading method B ′), if the amount of the carbodiimide compound added exceeds 5 parts by weight, the process of polymerization / depolymerization of the carbodiimide compounds is performed. The nucleating agent effect could not be obtained because of priority (Comparative Example 31). Further, it was found that when the kneading method D of kneading the carbodiimide compound first and then kneading the hydrazide compound is employed, the nucleating agent effect hardly appears (Comparative Example 32). First, only the carbodiimide compound is added and kneaded so that the weight of the carbodiimide compound finally blended is the same as in Comparative Example 29, then the hydrazide compound is kneaded, and then the carbodiimide compound is added. Similarly, when the kneading method E of kneading was adopted, the nucleating agent effect was not obtained (Comparative Example 33). After all, it can be said that it is important to obtain a high nucleating agent effect in the present invention to appropriately set the addition method and the addition amount of these two agents.

  In Comparative Examples 34 to 36, the results obtained when the carbodiimide compound other than the carbodiimide compound represented by the formula (II) -a was added and kneaded simultaneously with the terephthalic acid dihydrazide (kneading method B) were summarized. Compared with the case where the bifunctional cyclic carbodiimide represented by the above formula (II) -a was used (Comparative Example 25), the addition amount was set so that the number of moles of the carbodiimide group added was equal. As a result, when an acyclic monofunctional carbodiimide compound was used (Comparative Example 38: “STABAXOL (registered trademark)” I-LF), a non-cyclic type polymer carbodiimide compound was used (Comparative Example). 35: “Carbodilite (registered trademark)” LA-1), in the case of using a cyclic and monofunctional carbodiimide compound represented by the above formula (II) -b (Comparative Example 36) Was found to show little nucleating effect. Only when the bifunctional cyclic carbodiimide compound represented by the above formula (II) -a and terephthalic acid dihydrazide were combined, a specific high nucleating agent effect was obtained.

  In Comparative Examples 37 and 38, the conditions (Comparative Example 25) for promoting crystallization of stereocomplex polylactic acid found in the present invention are applied to homopoly-L-lactic acid to promote crystallization of homopolylactic acid. It is the result of examining whether it is done. As a result, it was found that the nucleating agent was not crystallized at all regardless of the addition of the nucleating agent, and it became clear that the organic nucleating agent system of the present invention was specifically effective for stereocomplex polylactic acid.

  The molded body made of the polylactic acid resin composition of the present invention has improved heat resistance because polylactic acid has stereocomplex crystals. For example, bumpers, radiator grills, side moldings, garnishes (decorative parts), wheels Automotive parts such as covers, aero parts, instrument panels, door trims, seat fabrics, door handles, floor mats, large and small home appliance housings, product packaging films, tarpaulins, various containers, bottles, and other molded products Useful as. In addition, when the polylactic acid resin composition of the present invention is used as a sheet, it can be laminated with paper or other polymer sheets and used as a laminate having a multilayer structure.

Claims (9)

A polylactic acid resin composition containing 90% by weight or more of polylactic acid, and in the DSC measurement in which the steps of temperature raising, holding and temperature lowering in the following steps (1) to (3) are repeated three times, the first and third A polylactic acid resin composition having a crystallization temperature (peak top temperature: T _cd ) of 155 ° C. or higher and a calorific value (H _c ) of 45 J / g or higher in the second temperature lowering step.
(1) Temperature increase from 30 ° C. to 260 ° C. at 20 ° C./min (2) Hold at 260 ° C. for 1 minute (3) Temperature decrease from 260 ° C. to 30 ° C. at 20 ° C./min   The polylactic acid resin composition according to claim 1, comprising 80 to 100% of stereocomplex crystals. The polylactic acid resin composition of Claim 1 or 2 containing the hydrazide compound represented by following formula (I), and the carbodiimide compound represented by following formula (II).
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.) 100 parts by weight of a polylactic acid resin, 0.01 to 5 parts by weight of a hydrazide compound represented by the following formula (I), and 0.01 to 5 parts by weight of a carbodiimide compound represented by the following formula (II) Polylactic acid resin composition.
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.) 100 parts by weight of polylactic acid, 0.01 to 5 parts by weight of a hydrazide compound represented by the following formula (I), and 0.01 to 5 parts by weight of a carbodiimide compound represented by the following formula (II) are melt-kneaded. A method for producing a polylactic acid resin composition.
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.)   The method for producing a polylactic acid resin composition according to claim 5, wherein the hydrazide compound and the carbodiimide compound are simultaneously added to the molten polylactic acid.   The method for producing a polylactic acid resin composition according to claim 5 or 6, wherein the polylactic acid is a blend of poly-L-lactic acid and poly-D-lactic acid.   The method for producing a polylactic acid resin composition according to claim 5 or 6, wherein the polylactic acid is a polylactic acid stereoblock copolymer. To 100 parts by weight of molten polylactic acid, 0.01 to 5 parts by weight of a hydrazide compound represented by the following formula (I) and 0.01 to 5 parts by weight of a carbodiimide compound represented by the following formula (II) A method for promoting crystallization of polylactic acid, which comprises adding the lactic acid.
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
(In the formula, Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ are each independently an aromatic group having 6 to 20 carbon atoms.)