JP2005042084A - Polylactic acid resin composition and molded product of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid resin composition making it possible that a polylactic acid capable of forming a stereocomplex crystal is made to selectively conduct stereocomplex crystallization, a speed of the crystallization is increased, and a molded product of the polylactic acid having enough crystallizability and a high ratio of the stereocomplex crystal is obtained by molding processes including injection molding. <P>SOLUTION: This polylactic acid resin composition contains a polylactic acid component capable of forming the stereocomplex crystal and an aromatic amide compound expressed by general formula (1) (X is -CONH- or -NHCO-; R is a 3-20C branched-chain alkyl; and m is an integer of 1 to 6). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polylactic acid resin composition and a molded body obtained by melt molding and crystallizing the composition.

  Polylactic acid has the property of degrading by the action of microorganisms and enzymes, so-called biodegradability, and the biodegradable product becomes lactic acid, carbon dioxide and water that are harmless to the human body, so it is an alternative to medical materials and general-purpose resins. It is attracting attention as. Such polylactic acid is a crystalline resin, but its crystallization rate is small, and actually it behaves like an amorphous resin. That is, since it softens rapidly and extremely near the glass transition temperature (usually less than 1/100 elastic modulus), it is difficult to obtain sufficient characteristics in terms of heat resistance, moldability, releasability, etc. .

  In order to improve such problems, Japanese Patent Application Laid-Open No. 10-87975 (Patent Document 1) discloses a polylactic acid resin (poly L-lactide) and an amide compound (for example, trimesic acid tris (t-butylamide)). 1,4-cyclohexanedicarboxylic acid dianilide, 2,6-naphthalenedicarboxylic acid dicyclohexylamide, N, N′-dibenzoyl-1,4-diaminocyclohexane, N, N′-dicyclohexanecarbonyl-1,5-diaminonaphthalene) It is described that the crystallization is improved and the mold releasability is improved by blending.

  Japanese Patent Laid-Open No. 9-25400 (Patent Document 2) discloses that poly-L lactic acid (PLLA) and poly-D lactic acid (PDLA) are melt blended and molded, compared with the case where each is used alone. It is described that crystallization is promoted.

On the other hand, in Japanese Patent Application Laid-Open No. 2002-356543 (Patent Document 3), a polylactic acid stereoblock copolymer composed of a segment composed of L lactic acid units and a segment composed of D lactic acid units forms a stereo complex having a high melting point. It is described that it is possible.
Japanese Patent Laid-Open No. 10-87975 Japanese Patent Laid-Open No. 9-25400 JP 2002-356543 A

  However, even with the method described in JP-A-10-87975, the rate of crystallization is not yet sufficient, and it is difficult to obtain polylactic acid having sufficient crystallinity by a molding method such as injection molding. there were.

  Even in the method described in JP-A-9-25400, there is a limit to the improvement of the crystallization speed, and it is still difficult to obtain polylactic acid having sufficient crystallinity by a molding method such as injection molding. there were. Further, although it has been suggested that the appearance of stereocomplex crystals of poly-L lactic acid and poly-D lactic acid may reduce the cooling time during melt molding, it is actually obtained by the method described in JP-A-9-25400. Most of the crystals were homocrystals, and the proportion of stereocomplex crystals was small.

  Furthermore, even in the method described in JP-A No. 2002-356543, the crystallization rate is low as in the above-mentioned blend of poly-L lactic acid and poly-D lactic acid, and a large crystallization rate and sufficient crystallinity are simultaneously achieved. An achievable polylactic acid stereoblock copolymer has not yet been obtained.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to selectively cause stereocomplex crystallization to polylactic acid capable of producing stereocomplex crystals and improve the crystallization speed. And Furthermore, a polylactic acid resin composition that makes it possible to obtain a molded product of polylactic acid that has sufficient crystallinity and a high stereocomplex crystal ratio by a molding method such as injection molding, and melt crystallization to crystallize it An object is to provide a compacted body.

  As a result of intensive studies to achieve the above object, the inventors of the present invention can obtain a molded product having a high ratio of stereocomplex crystals even when poly L lactic acid and poly D lactic acid are simply blended and crystallized. On the other hand, it has been found that the addition of an aromatic amide compound having a specific structure as a crystal accelerator surprisingly improves both the stereocomplex crystallization speed and the stereocomplex crystallization selectivity. Furthermore, as a result of intensive studies, the present inventors have added the aromatic amide compound having the above-mentioned specific structure as a crystallization accelerator to the polylactic acid stereoblock copolymer, thereby increasing the stereocomplex crystallization rate. Surprisingly, it was found that sufficient crystallinity was obtained, and the present invention was completed.

  That is, the polylactic acid resin composition of the present invention comprises a polylactic acid component capable of producing a stereocomplex crystal and the following general formula (1):

［式中、Ｘは−ＣＯＮＨ−又は−ＮＨＣＯ−を示し、Ｒは炭素数３〜２０の分岐鎖状アルキル基を示し、ｍは１〜６の整数を示す。］
で表される芳香族アミド化合物とを含有することを特徴とするものである。

[In formula, X shows -CONH- or -NHCO-, R shows a C3-C20 branched alkyl group, and m shows the integer of 1-6. ]
It contains the aromatic amide compound represented by these.

  Further, the molded article of the present invention comprises a polylactic acid component capable of producing a stereocomplex crystal, and the following general formula (1):

［式中、Ｘは−ＣＯＮＨ−又は−ＮＨＣＯ−を示し、Ｒは炭素数３〜２０の分岐鎖状アルキル基を示し、ｍは１〜６の整数を示す。］
で表される芳香族アミド化合物とを含有するポリ乳酸樹脂組成物を溶融成形して結晶化せしめたものであることを特徴とするものである。

[In formula, X shows -CONH- or -NHCO-, R shows a C3-C20 branched alkyl group, and m shows the integer of 1-6. ]
A polylactic acid resin composition containing an aromatic amide compound represented by the formula is melt-molded and crystallized.

  Here, the “polylactic acid component capable of generating a stereocomplex crystal” is a mixture of polylactic acids having different steric structures (for example, a blend of poly L lactic acid and poly D lactic acid) or an L-lactic acid unit. Polylactic acid stereoblock copolymers composed of segments and segments composed of D-lactic acid units, and mixtures / copolymers with other polymers, such as polymers with lactic acid as the basic skeleton, even pure substances and mixtures thereof It doesn't matter.

  The polylactic acid component capable of producing a stereocomplex crystal according to the present invention has an X-ray diffraction spectrum based on a wide-angle X-ray diffraction method when crystallized from the viewpoint of obtaining a molded body having a high crystallization speed and sufficient crystallinity. It is preferable to have diffraction peaks at Bragg angles (2θ) of 11.3 to 12.3 °, 20.1 to 21.1 °, and 23.3 to 24.3 °.

  By adding an aromatic amide compound having a specific structure as a crystallization accelerator to the polylactic acid component having such an X-ray diffraction spectrum, both stereocomplex crystallization speed and stereocomplex crystallization selectivity are obtained. The present inventors have found that is significantly improved.

  In the X-ray diffraction spectrum obtained by measuring the crystallized polylactic acid component by the wide-angle X-ray diffraction method, the above-described diffraction peaks (2θ = 11.3 to 12.3 °, 20.1 to 21.1 ° and 23. 3 to 24.3 °), other diffraction peaks, for example, diffraction peaks peculiar to homopolymers of polylactic acid (2θ = 14.1 to 15.1 °, 15.9 to 16.9 °) are observed. 18.3 to 19.3 ° and 21.6 to 22.6 °) may be observed.

Here, the above-mentioned “X-ray diffraction spectrum” indicates a spectrum measured under the following conditions.
X-ray source: CuKα,
Filter: Ni,
X-ray diffractometer: RINT2200 (manufactured by Rigaku Corporation),
Step: 0.01 °,
Scan speed: 2.0 ° / min.

Moreover, the crystallization method of the polylactic acid component sample at the time of measuring the above-mentioned X-ray diffraction spectrum is not particularly limited, and examples thereof include the following crystallization methods 1) to 4).
1) A method in which a polylactic acid resin is dissolved in a solvent, and then the solvent is cast and crystallized.
2) A method in which a polylactic acid resin is heated and melted, and then slowly cooled from the molten state to near room temperature for crystallization.
3) A method in which a polylactic acid resin is heated and melted, then cooled from a molten state to a predetermined temperature, and crystallized at that temperature.
4) A method in which a polylactic acid resin is heated and melted, cooled to room temperature in a molten state, and then crystallized at a predetermined temperature.

  The polylactic acid component according to the present invention is preferably a blend of poly-L lactic acid and poly-D lactic acid, a polylactic acid copolymer having a segment composed of L-lactic acid units and a segment composed of D-lactic acid units.

  The aromatic amide compound according to the present invention is preferably trimesic acid tris (sec-butylamide) and / or trimesic acid tris (iso-butylamide).

  In addition, when the present inventors use trimesic acid tris (sec-butylamide) as the aromatic amide compound, a stereocomplex crystal ratio is high, and a molded article of polylactic acid having high crystallinity can be obtained more easily and reliably. Has gained knowledge. In a blend of poly L lactic acid and poly D lactic acid, a combination of the above-mentioned aromatic amide compounds allows selective stereocomplex even when the content ratios of poly L lactic acid and poly D lactic acid in the blend are different. The present inventors have confirmed that a molded body of polylactic acid that can be crystallized and has a high ratio of stereocomplex crystals can be obtained (see Examples 12 to 19 described later).

Moreover, as a molded object of the said this invention obtained by the polylactic acid resin composition of the said invention, what the stereocomplex crystal ratio calculated | required from the following Formula (i) is 80% or more is preferable.
Stereo complex crystal ratio (%) = {B / (AZ + B)} × 100 (i)
[In the formula, A represents the melting endotherm (ΔHm, homo) of the homocrystal melting peak determined by DSC measurement, and B represents the melting endotherm (ΔHm, stereo) of the stereocomplex crystal melting peak determined by DSC measurement. , Z represents a value obtained by doubling the ratio of polylactic acid with a small content, where C is the ratio of poly-L lactic acid in the total mass of the blend and D is the ratio D of poly-D lactic acid. However, C + D = 1. ]

  If the stereocomplex crystal is contained in such a high ratio, the heat resistance, moldability, releasability, etc. of the molded body can be further improved.

  The “stereo complex crystal” is defined as follows. That is, in a blend of poly L lactic acid and poly D lactic acid, it refers to a eutectic in which poly L lactic acid molecules and poly D lactic acid molecules have a racemic crystal structure. The melting point (melting peak by DSC measurement) of poly-L lactic acid homocrystal and poly-D lactic acid homocrystal is generally 160 to 180 ° C., whereas the above-mentioned blend and polylactic acid copolymer stereocomplex The melting point of crystals (melting peak by DSC measurement) is generally 190 to 240 ° C.

  According to the present invention, a stereocomplex crystal can be selectively crystallized with respect to polylactic acid capable of producing a stereocomplex crystal, the crystallization rate is sufficiently high, and it has sufficient crystallinity by a molding method such as injection molding. A polylactic acid resin composition capable of obtaining a molded product of polylactic acid having a high stereocomplex crystal ratio is provided, and the polylactic acid resin composition is crystallized by melting and crystallizing the polylactic acid resin composition. It becomes possible to obtain a molded article having high properties.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  The polylactic acid resin composition of the present invention comprises a polylactic acid component capable of generating a stereocomplex crystal and an aromatic amide compound represented by the general formula (1). The polylactic acid component has a Bragg angle (2θ) of 11.3 to 12.3 °, 20.1 to 21.1 ° and 23.2 in the X-ray diffraction spectrum based on the wide-angle X-ray diffraction method when crystallized. A stereo block copolymer having a diffraction peak at 3 to 24.3 ° and having a blend of poly-L lactic acid and poly-D lactic acid, or a segment composed of L-lactic acid units and a segment composed of D-lactic acid units Is preferred.

  First, poly L lactic acid and poly D lactic acid constituting the blend according to the present invention will be described. Such poly-L lactic acid is represented by the following general formula (2):

［式中、ｎは整数を示す。］
で表される繰り返し単位を有するポリマーであり、他方、ポリＤ乳酸は下記一般式（３）：

[Wherein n represents an integer. ]
On the other hand, poly-D lactic acid is represented by the following general formula (3):

［式中、ｎは整数を示す。］
で表される繰り返し単位を有するポリマーであり、両者は鏡像関係にある。

[Wherein n represents an integer. ]
The polymer has a repeating unit represented by the formula (1), and both are mirror images.

  The polymerization method of poly-L lactic acid and poly-D lactic acid is not particularly limited, and may be direct polymerization of L-lactic acid or D-lactic acid, or ring-opening polymerization of L-lactide or D-lactide, which is a cyclic dimer of lactic acid. May be.

  The optical purity of poly L lactic acid and poly D lactic acid is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 98 mol% or more. When the optical purity of poly L lactic acid and poly D lactic acid is less than the above lower limit, crystallization is inhibited due to a decrease in stereoregularity, and the effects obtained by the present invention tend not to be sufficiently exhibited.

  Furthermore, the weight average molecular weights of poly L lactic acid and poly D lactic acid are not particularly limited, but each is preferably 10,000 or more, more preferably 50,000 or more, and further preferably 100,000 or more. When the weight average molecular weights of poly L lactic acid and poly D lactic acid are less than the lower limit, mechanical properties such as strength and elastic modulus tend to be insufficient. Moreover, it is preferable that the weight average molecular weights of poly L lactic acid and poly D lactic acid are 400,000 or less, respectively. If this weight average molecular weight is exceeded, the moldability tends to be insufficient. In addition, the weight average molecular weight in this invention means the weight average molecular weight of standard polystyrene conversion by gel permeation chromatography (GPC).

  Furthermore, the blend ratio of poly L lactic acid and poly D lactic acid is preferably 1 to 99% by mass: 99 to 1% by mass, more preferably 10 to 90% by mass: 90 to 10% by mass, and 30 to 70% by mass. : 70 to 30% by mass is particularly preferable. If the difference in the content ratio between poly L lactic acid and poly D lactic acid is too large, the content ratio of the stereocomplex crystals in the resulting molded article tends to decrease, and the degree of improvement in crystallization speed tends to decrease. In addition, as a blend of poly L lactic acid and poly D lactic acid, a diffraction peak (2θ = 11.3 to 12.3) peculiar to a stereocomplex crystal in an X-ray diffraction spectrum based on a wide angle X-ray diffraction method when crystallized. (°, 20.1 to 21.1 ° and 23.3 to 24.3 °).

  Furthermore, the method for forming a blend of poly-L lactic acid and poly-D lactic acid is not particularly limited. For example, a method of removing the solvent after mixing the two using a solvent such as chloroform or the like. A method of melt mixing by heating to a temperature of about 0C may be used.

  Next, the polylactic acid stereoblock copolymer according to the present invention will be described. Such a polylactic acid copolymer has the following general formula (4):

で表されるＬ−乳酸単位からなるセグメント（以下、「第１のセグメント」という）と、下記一般式（５）；

A segment consisting of an L-lactic acid unit represented by the following (hereinafter referred to as “first segment”), and the following general formula (5);

で表されるＤ−乳酸単位からなるセグメント（以下、「第２のセグメント」という）とを有する。

And a segment composed of a D-lactic acid unit (hereinafter referred to as “second segment”).

  The polylactic acid copolymer described above may be a copolymer in which the first segment and the second segment are alternately chemically bonded, and the chain length and ratio of the first segment and the second segment. Is not particularly limited. Then, from the polylactic acid copolymer obtained by the polymerization reaction described later, a diffraction peak (2θ = 11.3˜) peculiar to the stereocomplex crystal in the X-ray diffraction spectrum based on the wide-angle X-ray diffraction method when crystallized. It is preferred to select polylactic acid copolymers having 12.3 °, 20.1 to 21.1 ° and 23.3 to 24.3 °.

  Further, as the above-mentioned polylactic acid copolymer, a polylactic acid block copolymer bonded in a straight chain is preferable from the viewpoint of easily generating a stereocomplex crystal, and such a polylactic acid copolymer is included in its structure. It may have a graft structure or a star structure.

  Such a polylactic acid block copolymer can be synthesized by a lactide method. For example, L-lactide or D-lactide which is a lactic acid cyclic dimer is obtained using L-lactic acid or D-lactic acid as a starting material, A block copolymer is synthesized by sequentially performing a first step of performing ring-opening polymerization of one lactide having different optical activity and a second step of performing ring-opening polymerization of the other lactide having different optical activity. be able to. In this case, ring-opening polymerization may be performed using L-lactide or D-lactide as a starting material. Moreover, it is possible to accelerate a polymerization reaction by using a catalyst such as a metal organic acid salt (for example, tin octylate).

  The weight average molecular weight of the polylactic acid copolymer obtained by the above polymerization reaction is not particularly limited, but is preferably 10,000 or more, more preferably 50,000 or more, and still more preferably 100,000. That's it. When the weight average molecular weight of the polylactic acid copolymer is less than the lower limit, mechanical properties such as strength and elastic modulus tend to be insufficient. The weight average molecular weight of the polylactic acid copolymer is preferably 400,000 or less. If this weight average molecular weight is exceeded, the moldability tends to be insufficient.

  Next, the crystal accelerator according to the present invention will be described. That is, in the polylactic acid resin composition of the present invention, the following general formula (1), together with a polylactic acid component such as a blend of poly L lactic acid and poly D lactic acid or a polylactic acid copolymer as described above:

で表される芳香族アミド化合物が含有される。

The aromatic amide compound represented by these is contained.

  Here, in the above formula, X represents —CONH— or —NHCO—. R represents a branched alkyl group having 3 to 20 carbon atoms (preferably 3 to 6 carbon atoms), particularly preferably a sec-butyl group or an iso-butyl group. Furthermore, m in the above formula represents an integer of 1 to 6, preferably 3.

  In the present invention, by adding an aromatic amide compound having such a specific structure as a crystallization accelerator, both the stereocomplex crystallization speed and the stereocomplex crystallization selectivity are remarkably improved, and trimesic acid A particularly good effect is achieved when using tris (sec-butylamide) and / or trimesic acid tris (iso-butyramide).

Although the reason why such an effect is exerted by the aromatic amide compound is not clear, the present inventors infer as follows. That is, first, as a requirement for a polymer crystal accelerator,
1) Before the polymer crystallizes, it has high affinity with the polymer and good dispersibility in the polymer.
2) It becomes insoluble and becomes a nucleus during crystallization of the polymer,
Is mentioned. On the other hand, in the above aromatic amide compound, having an amide group achieves a high affinity with the polylactic acid component in the previous stage of crystallization, and it itself crystallizes by the hydrogen bond of the amide group. In addition, stacking between aromatic rings is considered to be insoluble when the polylactic acid component is crystallized.

Furthermore, polylactic acid homocrystals and stereocomplex crystals have different helix forms of polylactic acid molecules (homocrystal: 10 ₃ helix, stereocomplex crystal: 3 ₁ helix), so these molecules are collected (crystallization) It is thought that the molecular structure of the crystal promoter suitable for Although no clear correlation has yet been found in this regard, for example, the helix form of polylactic acid suitable for promoting crystal growth differs because the crystal structure of itself varies depending on the basic skeleton and substituents in aromatic amide compounds, for example. According to the aromatic amide compound of the present invention, it is considered that the production of only stereocomplex crystals has been specifically improved.

  The content of the aromatic amide compound in the polylactic acid resin composition of the present invention is preferably 0.05 to 10% by mass, and 0.1 to 8% by mass in the mixture of the polylactic acid component and the aromatic amide compound. More preferably, 0.1-5 mass% is especially preferable. If the content of the aromatic amide compound is less than the above lower limit, the content ratio of the stereocomplex crystal in the obtained molded product tends to decrease, and the degree of improvement in the crystallization speed tends to decrease. On the other hand, when the content of the aromatic amide compound exceeds the above upper limit, the plasticizer action by the aromatic amide compound is strongly expressed, the rigidity tends to decrease, and the nucleating agent bleeds out. There exists a tendency for the external appearance of a molded object to fall.

  Furthermore, in the polylactic acid resin composition of the present invention, a filler {talc, layered clay mineral (preferably a layered clay mineral organized with an organic onium salt), etc.}, a plasticizer, Additives such as pigments, stabilizers, antistatic agents, ultraviolet absorbers, antioxidants, flame retardants, mold release agents, lubricants, dyes, antibacterial agents, and end-capping agents may be further added. The content of such an additive is preferably 20% by mass or less in the polylactic acid resin composition of the present invention.

  Next, the molded product of the present invention will be described. That is, the molded product of the present invention is obtained by melt-molding and crystallizing the above-described polylactic acid resin composition of the present invention.

  When manufacturing the molded object of this invention, it is preferable that the temperature at the time of fuse | melting a polylactic acid resin composition is 160-260 degreeC. When this temperature is less than the above lower limit, the polylactic acid resin composition is not sufficiently melted, and various components tend not to be uniformly dispersed. On the other hand, if this temperature exceeds the above upper limit, the physical properties of the molded article obtained by reducing the molecular weight of polylactic acid tend to be impaired.

  The holding time at the melting temperature is preferably 0.1 to 30 minutes. If this holding time is less than the above lower limit, crystallization of polylactic acid in the resulting molded article tends to be insufficient. On the other hand, if this holding time exceeds the above upper limit, the molecular weight of polylactic acid decreases. There exists a tendency for the physical property of the obtained molded object to be impaired.

  Furthermore, as a method of crystallizing the molten polylactic acid resin composition, a method of cooling from a molten state to a temperature of 30 to 160 ° C. and holding at that temperature for 10 seconds to 30 minutes is preferable. If the holding time is less than the above lower limit, crystallization in the resulting molded product tends to be insufficient. On the other hand, if the holding time exceeds the upper limit, a long time is required to obtain the molded product, and it is practical. There is an unfavorable tendency.

  Further, when the molded product of the present invention is produced, the molding method is not particularly limited, and any of injection molding, extrusion molding, blow molding, inflation molding, profile extrusion molding, injection blow molding, vacuum pressure molding, spinning, etc. Can also be suitably used. And since the polylactic acid resin composition of the present invention achieves a sufficiently high crystallization rate, for example, even when it is subjected to injection molding, it has sufficient crystallinity and a high stereo complex crystal ratio It becomes possible to obtain a molded body of polylactic acid.

As described above, the molded product of the present invention obtained by the polylactic acid resin composition of the present invention preferably has a stereocomplex crystal ratio determined from the following formula (i) of 80% or more, more preferably 85% or more. More preferably, 90% or more is more preferable, and 95% or more is particularly preferable. Among the crystal parts in the obtained molded product, the higher the proportion of stereocomplex crystals, the better the heat resistance of the molded product. In the following formula (i), A represents the melting endotherm (ΔHm, homo) of the homocrystal melting peak obtained by DSC measurement, and B represents the melting endotherm (ΔHm, homogeneity of the stereocomplex crystal melting peak obtained by DSC measurement. , stereo), and Z represents a value obtained by doubling the ratio of polylactic acid with a low content, where C is the ratio of poly-L lactic acid in the total mass of the blend and D is the ratio D of poly-D lactic acid. However, C + D = 1.
Stereo complex crystal ratio (%) = {B / (AZ + B)} × 100 (i)

  The evaluation of the crystallization behavior by DSC is specifically based on the following method. That is, first, a part (5-10 mg) of a sample (polylactic acid resin composition) was heated to 255 ° C., held for 5 minutes and melted, and then cooled to 30 ° C. at a cooling rate of 20 ° C./min. Then, the crystallization temperature (Tc, cool) of polylactic acid and the calorific value (ΔHc, cool) based on the crystallization are obtained. Then, after the cooling, the sample is heated again to 255 ° C. at a rate of 10 ° C./min. The polylactic acid crystallization temperature (Tc, hot) at that time, the calorific value based on crystallization (ΔHc, hot ), Melting temperature (Tm, homo) and melting endotherm (ΔHm, homo) of the homocrystal melting peak where the peak top appears at 160 ° C to 180 ° C, and stereocomplex crystal melting where the peak top appears at 190 ° C to 230 ° C Obtain the melting temperature (Tm, stereo) of the peak and its endothermic amount (ΔHm, stereo). The melting endotherm (ΔHm, homo) of the homocrystal melting peak and the stereocomplex crystal melting peak (ΔHm, stereo) obtained by DSC measurement in this way, and the poly L-lactic acid and poly From the ratio of D lactic acid, the stereocomplex crystal ratio is calculated based on the above formula (i). The crystallization temperature and the melting temperature are both peak top temperatures. In addition, the crystallization speed is higher as the crystallization peak in the cooling process is observed on the higher temperature side, and the higher the amount of heat generated based on the crystallization in the cooling process, the higher the crystallinity improvement effect. In addition, although the said method demonstrated the blend body of poly L lactic acid and poly D lactic acid, the crystallization behavior by DSC can be evaluated by the same method also in the polylactic acid copolymer mentioned above.

  The shape, thickness and the like of the molded product of the present invention are not particularly limited, and may be any of injection molded products, extrusion molded products, compression molded products, blow molded products, sheets, films, yarns, fabrics and the like. More specifically, bumpers, radiator grills, side moldings, garnishes, wheel covers, aero parts, instrument panels, door trims, seat fabrics, door handles, floor mats and other automotive parts, home appliance housings, product packaging films , Waterproof sheets, various containers, bottles and the like. Moreover, when using the molded object of this invention as a sheet | seat, you may laminate | stack with paper or another polymer sheet, and may use it as a laminated body of a multilayer structure.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

[Example 1]
Poly L-lactic acid (PLLA: Toyota Motor Corporation, # 5400, weight average molecular weight 140,000, optical purity 99%) 0.5g, Poly D lactic acid (PDLA: Purac, PURASORB PD, weight average molecular weight 120,000, optical purity 99) %) 0.5 g and trimesic acid tris (sec-butylamide) 0.01 g were mixed with 10 mL of chloroform while stirring. The obtained mixture was hung on a petri dish, and chloroform was removed by drying at normal pressure and drying under reduced pressure to prepare a polylactic acid resin composition film. The DSC measurement was performed using the obtained film as a sample, and the obtained results are shown in Table 1 and FIG.

  A blend of poly L lactic acid and poly D lactic acid of Example 1 (mass ratio 1: 1) was dissolved in chloroform, and then chloroform was evaporated at room temperature to prepare a sample. Using this sample, an X-ray diffraction spectrum was measured based on a wide-angle X-ray diffraction method. The measurement results are shown in FIG. In the X-ray diffraction spectrum, it was confirmed that only diffraction peaks peculiar to the stereocomplex crystal were observed at 11.8 °, 20.6 ° and 23.8 ° (2θ). In the figure, “S” means a diffraction peak derived from a stereocomplex crystal.

[Example 2]
A film of a polylactic acid resin composition was prepared and obtained in the same manner as in Example 1 except that 0.01 g of trimesic acid tris (sec-butylamide) was replaced with 0.01 g of trimesic acid tris (iso-butyramide). The DSC measurement was performed using the film as a sample. The obtained results are shown in Table 1.

[Example 11]
L-lactide 100 g, 1,12-dodecanediol 3 g, and tin octylate 100 mg were placed in a reaction vessel, and then the pressure in the reaction vessel was reduced to 10 ⁻³ mmHg. Subsequently, the temperature was gradually increased with sufficient stirring and maintained at 150 ° C. for 3 hours. The reaction product was dissolved in chloroform and added dropwise to methanol to obtain poly-L lactic acid (hereinafter referred to as “PLLA”) having a weight average molecular weight of 23,000.

  Next, 40 g of D-lactide and 80 g of the resulting PLLA were uniformly dissolved at 200 ° C. in a nitrogen atmosphere. After cooling to room temperature, 40 mg of tin octylate was added and reacted at 150 ° C. for 3 hours. The reaction product was dissolved in hexafluoroisopropanol and added dropwise to methanol to obtain a polylactic acid block copolymer having a weight average molecular weight of 54,000 (hereinafter referred to as “PDLA-PLLA-PDLA”).

  Next, 20 g of L-lactide and 80 g of the obtained PDLA-PLLA-PDLA were uniformly dissolved at 220 ° C. in a nitrogen atmosphere. 20 mg of tin octylate was placed in a reaction vessel and reacted at 150 ° C. for 3 hours. The reaction product was dissolved in hexafluoroisopropanol and dropped into methanol to obtain a polylactic acid block copolymer having a weight average molecular weight of 81,000 (hereinafter referred to as “PLLA-PDLA-PLLA-PDLA-PLLA”).

  Next, 10 g of D-lactide and 80 g of the resulting PLLA-PDLA-PLLA-PDLA-PLLA were uniformly dissolved at 240 ° C. in a nitrogen atmosphere. After allowing to cool to room temperature, 10 mg of tin octylate was added and reacted at 150 ° C. for 3 hours. Dissolve the reaction product in hexafluoroisopropanol and add dropwise to methanol to prepare a polylactic acid block copolymer with a weight average molecular weight of 115,000 (hereinafter referred to as “PDLA-PLLA-PDLA-PLLA-PDLA-PLLA-PDLA”). Obtained.

  A sample of the polylactic acid copolymer obtained as described above was prepared in the same manner as in Example 1, and then an X-ray diffraction spectrum based on the wide-angle X-ray diffraction method was measured using this sample. The measurement results are shown in FIG. In the X-ray diffraction spectrum, only the diffraction peaks peculiar to the stereocomplex crystal were observed at 11.8 °, 20.6 ° and 23.8 ° (2θ). It was confirmed that crystals could be produced. In the figure, “S” means a diffraction peak derived from a stereocomplex crystal.

  Subsequently, 10 mL of hexafluoroisopropanol was added to and mixed with 0.01 g of the resulting PDLA-PLLA-PDLA-PLLA-PDLA-PLLA-PDLA and 0.01 g of trimesic acid tris (sec-butylamide). The obtained mixture was hung on a petri dish, and the solvent was removed by drying under normal pressure and reduced pressure to produce a polylactic acid resin composition film. The DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 2.

[Example 12]
A sample of a blend of poly-L lactic acid and poly-D lactic acid was prepared in the same manner as in Example 1 except that 0.9 g of poly-L lactic acid and 0.1 g of poly-D lactic acid in Example 1 were replaced. The X-ray diffraction spectrum based on the method was measured. The measurement results are shown in FIG. In the X-ray diffraction spectrum, diffraction peaks peculiar to a stereocomplex crystal at 11.8 °, 20.6 ° and 23.8 ° (2θ), and a diffraction peak peculiar to a homocrystal of polylactic acid (2θ = 14.7) °, 16.4 °, 18.7 ° and 22.1 °) were observed. From this, it was confirmed that the above-mentioned blend could produce a stereocomplex crystal. In the figure, “S” has the same meaning as above, and “H” means a diffraction peak derived from a polylactic acid homocrystal.

  Next, a film of the polylactic acid resin composition was produced from this blend in the same manner as in Example 1, and the DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 2.

[Example 13]
A polylactic acid resin composition film was prepared in the same manner as in Example 1 except that 0.8 g of poly-L lactic acid and 0.2 g of poly-D lactic acid were replaced with 0.2 g in Example 1, and the above-mentioned DSC was obtained using the obtained film as a sample. Measurements were made. The obtained results are shown in Table 2.
[Example 14]
A polylactic acid resin composition film was prepared in the same manner as in Example 1 except that 0.7 g of poly-L lactic acid and 0.3 g of poly-D lactic acid were replaced with 0.3 g in Example 1, and the above-mentioned DSC was obtained using the obtained film as a sample. Measurements were made. The obtained results are shown in Table 2.

[Example 15]
A film of a polylactic acid resin composition was prepared in the same manner as in Example 1 except that 0.6 g of poly L lactic acid and 0.4 g of poly D lactic acid were replaced with 0.4 g in Example 1, and the above-mentioned DSC was obtained using the obtained film as a sample. Measurements were made. The obtained results are shown in Table 2.

[Example 16]
A polylactic acid resin composition film was prepared in the same manner as in Example 1 except that 0.4 g of poly-L lactic acid and 0.6 g of poly-D lactic acid were changed to 0.6 g in Example 1, and the above-mentioned DSC was obtained using the obtained film as a sample. Measurements were made. The obtained results are shown in Table 2.

[Example 17]
A polylactic acid resin composition film was prepared in the same manner as in Example 1 except that 0.3 g of poly-L lactic acid and 0.7 g of poly-D lactic acid in Example 1 were used, and the above DSC was obtained using the obtained film as a sample. Measurements were made. The obtained results are shown in Table 2.

[Example 18]
A film of a polylactic acid resin composition was prepared in the same manner as in Example 1 except that 0.2 g of poly L lactic acid and 0.8 g of poly D lactic acid in Example 1 were replaced. Measurements were made. The obtained results are shown in Table 2.

[Example 19]
A polylactic acid resin composition film was prepared in the same manner as in Example 1 except that 0.1 g of poly-L lactic acid and 0.9 g of poly-D lactic acid were replaced with those of Example 1, and the above-mentioned DSC was obtained using the obtained film as a sample. Measurements were made. The obtained results are shown in Table 2.

[Comparative Example 1]
A polylactic acid resin composition film was prepared in the same manner as in Example 1 except that trimesic acid tris (sec-butylamide) in Example 1 was not added, and the DSC measurement was performed using the obtained film as a sample. It was. The obtained results are shown in Table 1 and FIG.

[Comparative Example 2]
A film of a polylactic acid resin composition was produced in the same manner as in Example 1 except that 0.01 g of ethylenebis-12-hydroxystearic acid amide was used instead of trimesic acid tris (sec-butylamide) in Example 1. The DSC measurement was performed using the film as a sample. The obtained results are shown in Table 1 and FIG.

[Comparative Examples 3 to 10]
Trimesic acid tris (sec-butylamide) in Example 1
(Comparative Example 3) Trimesic acid tris (n-butylamide) 0.01 g,
(Comparative Example 4) Trimesic acid tris (n-octylamide) 0.01 g,
Comparative Example 5 Trimesic acid tris (n-octadecylamide) 0.01 g
(Comparative Example 6) 2,6 naphthalenedicarboxylic acid di-n-butylamide 0.01 g,
(Comparative Example 7) 0.01 g of 2,6-naphthalenedicarboxylic acid ditert-butylamide
(Comparative Example 8) 2,6 naphthalenedicarboxylic acid diiso-butyramide 0.01 g,
(Comparative Example 9) 2,6 naphthalenedicarboxylic acid disec-butylamide 0.01 g,
(Comparative Example 10) 2,6 naphthalene dicarboxylic acid dicyclohexylamide 0.01 g,
A film of a polylactic acid resin composition was produced in the same manner as in Example 1 except that the above-described DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 1.

[Comparative Example 11]
A film of a polylactic acid resin composition in the same manner as in Example 1 except that 0.9 g of poly-L lactic acid and 0.1 g of poly-D lactic acid in Example 1 were not added, and trimesic acid tris (sec-butylamide) was not added. The above-described DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 2.

[Comparative Example 12]
A film of a polylactic acid resin composition in the same manner as in Example 1, except that 0.8 g of poly-L lactic acid and 0.2 g of poly-D lactic acid in Example 1 were not added, and trimesic acid tris (sec-butylamide) was not added. The above-described DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 2.

[Comparative Example 13]
A film of a polylactic acid resin composition in the same manner as in Example 1 except that 0.7 g of poly L lactic acid and 0.3 g of poly D lactic acid in Example 1 were not added, and trimesic acid tris (sec-butylamide) was not added. The above-described DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 2.

[Comparative Example 14]
A film of a polylactic acid resin composition in the same manner as in Example 1 except that 0.6 g of poly L lactic acid and 0.4 g of poly D lactic acid in Example 1 were not added, and trimesic acid tris (sec-butylamide) was not added. The above-described DSC measurement was performed using the obtained film as a sample. The obtained results are shown in Table 2.

  As is clear from the results shown in Table 1 and FIG. 1, when the polylactic acid resin composition of the present invention was used, only stereocomplex crystals were produced, and the crystallization speed and the crystallinity improvement effect were also improved. It was excellent. On the other hand, in Comparative Example 1 in which no crystallization accelerator was added, no peak was observed during the cooling process, and crystallization did not proceed. In addition, in the case where a substance other than the aromatic amide compound according to the present invention is added as a crystallization accelerator (Comparative Examples 2 to 10), the ratio of stereocomplex crystals is low, and the effect of improving the crystallization speed and crystallinity is also achieved. It was inferior. In Table 1, “stereocrystal ratio” means a stereocomplex crystal ratio.

  As is apparent from the results shown in Table 2, even when the blend ratio of poly-L lactic acid and poly-D lactic acid was changed as in Examples 12 to 19, the stereocomplex crystal ratio was extremely high and sufficient crystallization speed was obtained. A polylactic acid having the following was obtained. In addition, when a polylactic acid stereoblock copolymer was used, only stereocomplex crystals were produced, and the crystallization rate was sufficiently high. From the above results, it was confirmed that polylactic acid having sufficient crystallinity and a high stereocomplex crystal ratio can be obtained by using the above-mentioned polylactic acid resin composition. On the other hand, in Comparative Examples 11 to 14 in which no crystallization accelerator was added, the ratio of stereocomplex crystals was low, and the crystallization rate was inferior. In Table 2, “stereocrystal ratio” means a stereocomplex crystal ratio.

[Reference Example 1]
After preparing a sample of poly-L lactic acid by the same method as in Example 1, the sample was used to measure an X-ray diffraction spectrum by wide-angle X-ray diffraction. The measurement results are shown in FIG. In the X-ray diffraction spectrum, only a diffraction peak peculiar to the homocrystal of polylactic acid was observed, and it was confirmed that a diffraction peak peculiar to the stereocomplex crystal was not observed. In the figure, “H” has the same meaning as described above.

It is a graph which shows the result of having performed DSC measurement using the film of the polylactic acid resin composition obtained in Example 1 as a sample. It is a graph which shows the result of having performed DSC measurement using the film of the polylactic acid resin composition obtained in Comparative Example 1 as a sample. It is a graph which shows the result of having performed DSC measurement using the film of the polylactic acid resin composition obtained in Comparative Example 2 as a sample. 2 is a graph showing an X-ray diffraction spectrum of a polylactic acid component of Example 1. 3 is a graph showing an X-ray diffraction spectrum of a polylactic acid component of Example 11. 4 is a graph showing an X-ray diffraction spectrum of a polylactic acid component of Example 12. 4 is a graph showing an X-ray diffraction spectrum of polylactic acid in Reference Example 1.

Claims (11)

A polylactic acid component capable of producing a stereocomplex crystal and the following general formula (1):

[In formula, X shows -CONH- or -NHCO-, R shows a C3-C20 branched alkyl group, and m shows the integer of 1-6. ]
A polylactic acid resin composition comprising an aromatic amide compound represented by the formula:   When the polylactic acid component is crystallized, the Bragg angles (2θ) of 11.3 to 12.3 °, 20.1 to 21.1 °, and 23.3 to 24 in the X-ray diffraction spectrum based on the wide-angle X-ray diffraction method are used. The polylactic acid resin composition according to claim 1, which has a diffraction peak at 3 °.   The polylactic acid resin composition according to claim 1 or 2, wherein the polylactic acid component is a blend of poly L lactic acid and poly D lactic acid.   The polylactic acid resin composition according to claim 1 or 2, wherein the polylactic acid component is a polylactic acid copolymer having a segment composed of L-lactic acid units and a segment composed of D-lactic acid units.   The polylactic acid resin composition according to any one of claims 1 to 4, wherein the aromatic amide compound is trimesic acid tris (sec-butylamide) and / or trimesic acid tris (iso-butyramide). object. A polylactic acid component capable of producing a stereocomplex crystal and the following general formula (1):

[In formula, X shows -CONH- or -NHCO-, R shows a C3-C20 branched alkyl group, and m shows the integer of 1-6. ]
A molded product obtained by melt-molding and crystallizing a polylactic acid resin composition containing an aromatic amide compound represented by the formula:   When the polylactic acid component is crystallized, the Bragg angles (2θ) of 11.3 to 12.3 °, 20.1 to 21.1 °, and 23.3 to 24 in the X-ray diffraction spectrum based on the wide-angle X-ray diffraction method are used. The molded article according to claim 6, which has a diffraction peak at 3 °.   The molded article according to claim 6 or 7, wherein the polylactic acid component is a blend of poly L-lactic acid and poly-D lactic acid. The molded product according to any one of claims 6 to 8, wherein a stereocomplex crystal ratio obtained from the following formula (i) is 80% or more.
Stereo complex crystal ratio (%) = {B / (AZ + B)} × 100 (i)
[In the formula, A represents the melting endotherm (ΔHm, homo) of the homocrystal melting peak determined by DSC measurement, and B represents the melting endotherm (ΔHm, stereo) of the stereocomplex crystal melting peak determined by DSC measurement. , Z represents a value obtained by doubling the ratio of polylactic acid with a small content, where C is the ratio of poly-L lactic acid in the total mass of the blend and D is the ratio D of poly-D lactic acid. However, C + D = 1. ]   The molded product according to claim 6 or 7, wherein the polylactic acid component is a polylactic acid copolymer having a segment composed of L-lactic acid units and a segment composed of D-lactic acid units.   The molded article according to any one of claims 6 to 10, wherein the aromatic amide compound is trimesic acid tris (sec-butylamide) and / or trimesic acid tris (iso-butylamide).

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