JP2009249583A - Polylactic acid composition and molding - Google Patents

Abstract

An object of the present invention is to provide a composition that provides a molded article having excellent heat resistance, a small amount of foreign matter insoluble in E-sol, and good light transmittance.
The present invention comprises polylactic acid (B) containing 90 mol% or more of L-lactic acid units and polylactic acid (C) containing 90 mol% or more of D-lactic acid units, and the former (B) / The latter (C) has a weight ratio of 10/90 to 90/10, and is a composition (A) that simultaneously satisfies the following requirements (a) to (c).
(A) The weight average molecular weight is 80,000 or more and 500,000 or less.
(B) The degree of stereoification (S) measured with a differential scanning calorimeter (DSC) is 80% or more.
(C) The undissolved content when the composition (A) is dissolved in E-sol is 0.1% by weight or less based on the composition (A).
[Selection figure] None

Description

  The present invention relates to a polylactic acid composition and a molded article that give a molded article excellent in light transmittance and heat resistance.

Due to environmental problems such as global warming, concerns over oil depletion and supply conditions in oil-producing countries, oil prices have soared and the development of non-petroleum resins is required. Among them, polylactic acid has not only the possibility of being a substitute for petroleum-based resin, but also has characteristics in optical properties such as transparency and low refractive index, and application development utilizing this is expected.
However, polylactic acid usually has a low crystal melting point of about 160 ° C., and there is a problem in heat resistance such as melting and deformation. In addition, since biodegradability and degradation under a moist heat environment proceed relatively quickly, there are problems in stability of physical properties, and there are drawbacks such as limited use.
On the other hand, it is known that stereocomplex polylactic acid is formed by mixing poly-L-lactic acid composed of L-lactic acid units and poly-D-lactic acid composed of D-lactic acid units in a solution or in a molten state ( Patent Document 1 and Non-Patent Document 1). This stereocomplex polylactic acid has a high melting point of 200 to 230 ° C. compared to poly L-lactic acid and poly D-lactic acid, and has found an interesting phenomenon such as high crystallinity.
This stereocomplex polylactic acid can be used in high-temperature processing and heat-resistant applications, as well as improved biodegradability and durability under wet heat environments, optical films and packaging films that take advantage of its transparency Prolonged life expectancy is expected with highly transparent film.

For stereocomplex polylactic acid, molding methods such as melt molding and solution casting have been proposed. In particular, it is expected to produce a molded product of good quality at a cost that can withstand practical use by a melt molding method having excellent productivity.
However, polylactic acid is a kind of aliphatic polyester, has low heat resistance, heat decomposition reaction and deterioration reaction proceed by heating, and insoluble foreign matter may be generated in E-sol which is a good solvent for polylactic acid. Not a few. Such a foreign substance insoluble in E-sol itself causes light scattering in the molded product and deteriorates the light transmission property, and the composition containing the foreign substance has non-uniform fluidity of the molten resin during melt molding. This may cause flow spots in the molded product and deteriorate the light transmittance of the molded product.
The deterioration of light scattering and light transmittance of molded products due to such flow spots often brings serious results, and in order to obtain molded products with good light transmittance, it is necessary to appropriately control the content of foreign matter. . However, no proposal has yet been made to achieve both the E-sol insoluble amount of polylactic acid and its molded product and the physical properties of the molded product, particularly light transmittance.

For molded articles, in order to obtain excellent mechanical properties, it is preferable that the weight average molecular weight of polylactic acid is high, but the formation of stereocomplexes is difficult to proceed as the weight average molecular weight is high, and heat treatment at higher temperatures is performed. In addition, higher temperatures are essential in the melt molding of the composition. The above-mentioned tendency is further promoted by such high-temperature heat treatment and melt molding, and it is necessary to achieve both the weight average molecular weight and the E-sol insoluble matter, but no proposal in such technical category has been made yet. Not.
JP 63-24014 A Macromolecules, 24, 5651 (1991).

  An object of the present invention is to provide a composition that is excellent in heat resistance, has a small amount of foreign matter insoluble in E-sol, and gives a molded article having good light transmittance. Another object of the present invention is to provide a molded article, particularly a film, comprising the composition. Furthermore, the objective of this invention is providing the manufacturing method of this film.

As a result of intensive studies to achieve the above object, the present inventor has completed the present invention. That is, the present invention contains polylactic acid (B) containing 90 mol% or more of L-lactic acid units and polylactic acid (C) containing 90 mol% or more of D-lactic acid units, and the former (B) / the latter ( The weight ratio of C) is 10/90 to 90/10, and the composition (A) satisfies the following requirements (a) to (c) at the same time.
(A) The weight average molecular weight is 80,000 or more and 500,000 or less.
(B) The degree of stereoification (S) measured with a differential scanning calorimeter (DSC) is 80% or more.
Here, the degree of stereogenicity (S) is expressed by the following formula (1).
S = {ΔHmsc / (ΔHmsc + ΔHmh)} × 100 (1)
(In the formula, ΔHmh represents the heat of crystal melting (J / g) of the melting peak of less than 190 ° C. in DSC measurement. ΔHmcs is the heat of crystal melting (J / g of the melting peak of 190 ° C. or more in DSC measurement). )
(C) The undissolved content when the composition (A) is dissolved in E-sol is 0.1% by weight or less based on the composition (A).

Moreover, this invention consists of this composition (A), and is a molded article which satisfies the following requirements (d)-(f) simultaneously.
(D) The weight average molecular weight is 80,000 or more and 500,000 or less.
(E) The undissolved content when dissolved in E-sol is 0.1% by weight or less based on the composition (A).
(F) The wavelength 400 nm to 700 nm light transmittance of a molded product having a thickness of 1 mm is 80% or more.

  Further, the present invention includes a method for producing a film, which comprises melt-extruding the composition (A) from a die, and the temperature (° C.) of the composition (A) at the time of melt-extrusion is in the range of Tmsc to (Tmsc + 100). To do. Here, Tmsc represents the temperature (° C.) of the crystal melting peak at 190 ° C. or higher in DSC measurement.

  The present invention includes an optical film or packaging film comprising the composition (A).

  The composition of the present invention is excellent in heat resistance, has a small amount of foreign matter insoluble in E-sol, and gives a molded article having good light transmittance. The molded article of the present invention, particularly the film, is excellent in heat resistance and light transmittance. According to the present invention, an optical or packaging film having good transparency is provided.

Hereinafter, the present invention will be described in detail.
<Composition (A)>
The composition (A) of the present invention contains polylactic acid (B) and polylactic acid (C). The weight ratio of polylactic acid (B) to polylactic acid (C) is 10/90 to 90/10, preferably 40/60 to 60/40, with the former (B) / the latter (C).
(Polylactic acid (B))
Polylactic acid (B) contains 90 mol% or more of L-lactic acid units. The content of the L-lactic acid unit in the polylactic acid (B) is 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 98 to 100 mol%. The polylactic acid (B) may contain 0 to 10 mol% of components other than the L-lactic acid unit. The content of units other than the L-lactic acid unit is 0 to 10 mol%, preferably 0 to 5 mol%, more preferably 0 to 2 mol%.
The components that can be copolymerized are not particularly limited. For example, hydroxycarboxylic acids such as D-lactic acid, glycolic acid, caprolactone, butyrolactone, propiolactone, ethylene glycol, 1,3-propanediol, 1, 2-propanediol, 1,4-propanediol, 1,5-propanediol, hexanediol, octanediol, decanediol, dodecanediol, aliphatic diols having 2 to 30 carbon atoms, succinic acid, maleic acid, adipine One or more monomers selected from acids, aromatic dicarboxylic acids having 2 to 30 carbon atoms, terephthalic acid, isophthalic acid, hydroxybenzoic acid, hydroquinone and the like, aromatic dicarboxylic acids and the like can be selected.
The polylactic acid (B) preferably has a weight average molecular weight in the range of 100,000 to 500,000, more preferably 140,000 to 250,000.
The polylactic acid (B) has crystallinity, and its melting point is preferably 150 ° C. to 190 ° C., more preferably 160 ° C. to 190 ° C. When polylactic acid (B) falling within this range is used, the composition (A) can form a stereocomplex crystal having a high melting point, and the crystallinity can be increased.

(Polylactic acid (C))
Polylactic acid (C) contains 90 mol% or more of L-lactic acid units. The content of the L-lactic acid unit in the polylactic acid (B) is 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 98 to 100 mol%. The polylactic acid (C) may contain 0 to 10 mol% of components other than the L-lactic acid unit. The content of units other than the L-lactic acid unit is 0 to 10 mol%, preferably 0 to 5 mol%, more preferably 0 to 2 mol%. The component which can be copolymerized can illustrate the same thing as polylactic acid (B).
The polylactic acid (C) preferably has a weight average molecular weight in the range of 100,000 to 500,000, more preferably 140,000 to 250,000.
The polylactic acid (C) has crystallinity, and its melting point is preferably 150 to 190 ° C, more preferably 160 to 190 ° C. When polylactic acid (C) falling within this range is used, the composition (A) can form a stereocomplex crystal having a high melting point, and the crystallinity can be increased.

  The method for producing polylactic acid (B) and polylactic acid (C) is not particularly limited, and can be suitably produced by a conventionally known method. For example, it may be produced by a method of directly dehydrating and condensing each type of lactic acid, or by a method of ring-opening polymerization after once each lactic acid is dehydrated and cyclized to lactide.

Any catalyst can be used as the catalyst used in these production methods as long as the poly L-lactic acid component and the poly D-lactic acid component can be polymerized so as to have the above-mentioned predetermined characteristics. Suitable for divalent tin compounds such as tin oxide, tin chloride, tin alkoxide, tetravalent tin compounds such as tin oxide, butyltin oxide, ethyltin oxide, metal tin, zinc compound, aluminum compound, calcium compound, lanthanide compound, etc. It can be illustrated as a thing.
The amount of the catalyst used is 0.42 × 10 ^{−4 to} 840 × 10 ⁻⁴ (mol) per kg of lactide, and the reactivity, the color tone of the polylactic acid obtained, stability, the composition (A) and the molding of the composition 1.68 × 10 ^{−4 to} 42.1 × 10 ⁻⁴ mol, particularly preferably 2.53 × 10 ^{−4 to} 16.8 × 10 ⁻⁴ mol is used in consideration of the ability of the product to produce E-sol insoluble foreign matter. The

The polylactic acid (B) and the polylactic acid (C) are prepared by removing the polymerization catalyst by a conventionally known method, for example, by washing with a solvent, or by deactivating or deactivating the catalytic activity. It is preferable in order to suppress the melt stability, wet heat stability and E-sol insoluble foreign matter of the molded product.
For example, in the case of polylactic acid subjected to melt ring-opening polymerization in the presence of a metal-containing catalyst, examples of the deactivator used for catalyst deactivation include the following compounds.

That is, an organic ligand consisting of a group of chelating ligands having an imino group and capable of coordinating with a specific metal-based polymerization catalyst, and dihydridooxoline (I) acid, dihydridotetraoxodiphosphorus (II, II) acid, Hydridotrioxoline (III) acid, dihydridopentaoxodiphosphoric acid (III), hydridopentaoxodi (II, IV) acid, dodecaoxohexaphosphorus (III, III), hydridooctaoxotriphosphorus (III, IV, IV ) Acid, octaoxotriphosphoric acid (IV, III, IV), hydridohexaoxodiphosphoric acid (III, V), hexaoxodiphosphoric acid (IV), decaoxotetraphosphoric acid (IV), hendecaoxotetraphosphoric acid (IV) A low oxidation number phosphoric acid having an acid number of 5 or less, such as eneoaoxotriphosphoric acid (V, IV, IV), xH ₂ O. Polyphosphoric acid represented by yP ₂ O ₅ , x / y = 3 orthophosphoric acid, 2> x / y> 1, and referred to as diphosphoric acid, triphosphoric acid, tetraphosphoric acid, pentaphosphoric acid or the like based on the degree of condensation Acid and a mixture thereof, metaphosphoric acid represented by x / y = 1, in particular, trimetaphosphoric acid, tetrametaphosphoric acid, 1> x / y> 0, and a network having part of the phosphorus pentoxide structure Examples include ultraphosphoric acid having a structure, monovalent and polyhydric alcohols of these acids, partial esters of polyalkylene glycols, and complete ethers. Phosphooxo acids or their acidic esters are preferably used because of their catalyst deactivation ability.
These deactivators may be used singly or in some cases in combination. These deactivators are 0.3 to 20 equivalents, more preferably 0.5 to 15 equivalents, more preferably 0.5 to 10 equivalents, particularly preferably 0, per equivalent of the metal element of the aforementioned metal-containing catalyst. .6-7 equivalents are used. If the amount of the deactivator used is too small, the activity of the catalyst metal cannot be lowered sufficiently, and if it is used excessively, the deactivator may cause decomposition of the resin, which is not preferable.

In addition, the polylactic acid (B) and polylactic acid (C) used in the present invention have a weight average molecular weight reduction (hereinafter sometimes abbreviated as melt stability) of 20% or less when melted at 260 ° C. It is preferable. When the molecular weight is drastically reduced at high temperature, melt molding becomes difficult, and physical properties of the obtained molded product are lowered, which is not preferable. The deactivation treatment can suitably improve the melt stability.
The weight average molecular weight of the composition (A) is 80,000 to 500,000. In such a molecular weight range, the composition (A) has a high degree of stereogenicity and is particularly suitable for forming a molded article having good transparency, particularly a film, and a composition (A) molded article having good mechanical properties. But you can give a film.

In order to increase the heat resistance and mechanical properties of the molded product, it is preferable that the weight average molecular weight is high. However, if the weight average molecular weight of the composition (A) is larger than the above range, a stereocomplex structure is formed by heat treatment. It is difficult to produce a stereocomplex, and it causes the thermal decomposition of the stereocomplex polylactic acid including the polylactic acid component to promote the generation of E-sol insoluble foreign matter.
In addition, when such thermal decomposition proceeds, the hue of the composition (A) deteriorates. In extreme cases, the composition (A) may be colored so as not to be suitable for industrial use. This problem is also an important issue. is there.

  From the viewpoint of the weight average molecular weight, no proposal has been made to achieve both mechanical properties and ability to suppress foreign matter formation, and the present inventors will make clear for the first time this time. That is, from the above viewpoint, the weight average molecular weight is preferably 80,000 to 300,000, more preferably 90,000 to 250,000, and particularly preferably 100,000 to 200,000. Further, if the weight average molecular weight is less than 70,000, it may be difficult to mold a molded product, and at the same time, the mechanical properties may be poor.

The composition (A) of the present invention has a stereogenicity (S) represented by the following formula (1) in DSC measurement of 80% or more.
S = {ΔHmsc / (ΔHmsc + ΔHmh)} × 100 (1)
In the formula, ΔHmh represents the heat of crystal fusion (J / g) of the melting peak of less than 190 ° C. in DSC measurement. ΔHmcs represents the heat of crystal fusion (J / g) of the melting peak at 190 ° C. or higher in DSC measurement.
The composition (A) having such a degree of stereogenicity forms a stereocomplex polymer at a high ratio, and can be formed into a molded product, particularly a film, having high heat resistance and good transparency. When the degree of stereoification is low, the stereocomplex crystal structure is difficult to be expressed during melt molding, and the heat resistance and mechanical strength of the molded product are difficult to be expressed.

In the present invention, the composition (A) has an undissolved content of 0.1% by weight or less based on the composition (A) when dissolved in E-sol. If the E-sol insoluble matter is present beyond the above range, the molded product of the composition (A), in particular, the light transmittance of the film is often poor, and it is unsuitable to use the composition (A) as a transparent application. It becomes the range. In other words, if the insoluble matter is present in excess of 0.1% by weight, not only the light transmittance is deteriorated due to the mixed foreign matter, but also the uniform flow is hindered in the flow zone of the melt molding machine at the time of melt molding. It may cause flow spots on the product. E-sol is a mixed solvent of tetrachloroethane / phenol = (6/4: weight).
Although it is better that the amount of insoluble matter in E-sol is small, it is difficult industrially considering the cost required to make it substantially zero, but the amount of insoluble matter in E-sol is 0.1 wt% to 0.0001 wt%. It is preferable to make it into a range. More preferably, it is in the range of 0.08 wt% to 0.0001 wt%, more preferably 0.07 wt% to 0.0003 wt%. Within such a foreign matter amount range, it is possible to improve the transparency of the melt-formed product, particularly the film.

The composition (A) of the present invention can be obtained by allowing polylactic acid (B) and polylactic acid (C) to coexist, mixing, and heat-treating at 230 to 300 ° C. More preferably, it can be obtained by melt-kneading both components under shearing conditions.
Here, as a mixing apparatus used for melt kneading, a reactor with a batch type stirring blade, a continuous reactor, a biaxial or uniaxial extruder, and more preferably an extruder having a mixing unit, self-cleaning For example, an N-SCR manufactured by Mitsubishi Heavy Industries, a finisher type non-axial saddle type stirring device, and the like can be used.
As an extruder that is a melt-kneading machine with self-cleaning ability, an extruder having a mixing part, for example, a barrier type mixing screw with a flute groove or a spiral barrier type mixing screw, can effectively promote stereocomplexization, and melt mixing time Is constant, and the formation of E-sol insolubles can be suppressed, which is preferable.
As such a mixed heat treatment apparatus material, particularly a surface material, a material that does not promote decomposition or deterioration of polylactic acid is preferable in order to suppress the formation of E-sol insoluble matter. Examples of preferable materials include austenite, titanium, nickel, chromium and other metals known by names such as SUS316, alloys containing them, carbides such as tungsten carbide, nitrides such as titanium nitride, and ceramics such as enamel. .

The apparatus main body may be manufactured using these materials, and it is also preferable to cover the surface of the apparatus that may come into contact with the resin with these materials.
Prior to melt-kneading, both components present in a solid state are mixed using a tumbler-type powder mixer, continuous powder mixer, various milling devices, etc., and both are uniformly and intimately mixed. It is preferable.

Here, the heat treatment at 230 to 300 ° C. means contacting and maintaining polylactic acid (B) and polylactic acid (C) in a temperature range of 230 ° C. to 300 ° C. In consideration of the ability to generate foreign substances insoluble in E-sol, the temperature of the heat treatment is preferably 240 to 295 ° C. More preferably, it is the range of 250 to 293 degreeC. Especially preferably, it is the range of 260 to 285 degreeC. If it exceeds 300 ° C., it is difficult to suppress the generation and decomposition reaction of foreign substances, which is not preferable. When the temperature is lower than 230 ° C., a case where the generation of the stereo complex is low occurs.
The heat treatment time is determined in relation to the heat treatment temperature in order to achieve both stereocomplex formation and E-sol insoluble matter, but at a heat treatment temperature as low as about 240 ° C., 0.1 to 30 minutes, preferably 5 to 10 minutes. In the range of minutes, more preferably 1 to 10 minutes. Moreover, at the temperature of about 290 degreeC, it is the range for 0.1 minute-10 minutes, Preferably it is 0.5 minute-8 minutes, More preferably, it is the range for 1 minute-5 minutes.
The heat treatment can be applied under an inert gas atmosphere in any atmosphere of normal pressure, pressurized pressure, or reduced pressure. In order to make the E-sol insoluble matter in the composition (A) 0.1% by weight or less, in addition to the resin melting treatment region, the raw material resin storage region, the transport region, the supply region, the resin heating region, the melt extrusion die It is preferable to keep the cooling region where the composition (A) is in the molten state while leaving the inside and the die in an inert gas atmosphere. At this time, it is recommended that the oxygen concentration in the inert gas atmosphere be controlled to a low level of 100 ppm or less, preferably 50 ppm or less, more preferably 10 mmp or less.
In order to control the oxygen concentration in the inert gas atmosphere gas within this range, a high-purity inert gas having an oxygen content of 10 ppm or less is used as the atmosphere gas and at the same time shut off from the oxygen gas in the inert gas atmosphere region. It is preferable to improve the property. Further, the replacement rate with the inert gas is made sufficiently fast, for example, 1 time / minute to 100 times / minute, preferably 3 times / minute to 50 times / minute, more preferably 5 times / minute to 40 times / minute. It is preferable to do.

Furthermore, the raw material polylactic acid (B), (C) and various additives are stored in an inert gas atmosphere prior to use, or deoxygenation such as vacuum processing or inert gas replacement is performed during storage or prior to use. This is also preferable for reducing E-sol insoluble matter.
As the inert gas, nitrogen gas, argon gas, helium gas, carbon dioxide gas, organic gas or a mixed gas thereof can be used, but nitrogen gas is preferably used industrially from the viewpoint of purity and cost. I can do it.

  In the composition (A) and the molded article of the present invention, application of a conventionally known crystallization nucleating agent is preferable for producing a stereocomplex, improving the stereogenicity and controlling the stereocrystallization degree of the molded article. When such a crystallizing nucleating agent is present, the stereogenicity of the composition (A) and the molded article can be 90% or more, preferably 95% or more, and more preferably 97% or more.

In particular, this is effective for setting the degree of stereogenicity, which is a single peak of a high melting point peak due to stereocomplex polylactic acid in DSC measurement, to 100%.
Molded articles having a high crystallinity, that is, a high stereo crystallinity of 30% to 60% can be obtained from such a composition having a stereocrystallization degree. Realization of the crystallinity in such a range is suitable for achieving a high level of heat resistance of the molded product.

A molded product having a degree of crystallinity outside the above range has a heat resistance approaching that of a polylactic acid homopolymer, and the meaning of stereocomplex formation is small. In addition, since polylactic acid homopolymer and stereocomplex polylactic acid coexist as an equilibrium composition, increasing the crystallinity beyond 60% requires great efforts and is not recommended from the viewpoint of cost. That is, a composition having such a stereogenicity and a low E-sol insoluble matter generation ability is suitable for realizing a molded article having excellent heat resistance, mechanical properties and light transmittance.
As the crystallization nucleating agent, a conventionally known crystallization nucleating agent, for example, a crystallization nucleating agent described in JP-A No. 2003-192848 can be preferably used.
In the present invention, among these crystallizing nucleating agents, a clear mechanism of action is unknown, but triclinic crystals suitable for improving the degree of stereoization and improving the transparency and heat resistance of the molded product. Particles and / or phosphate metal salts are preferably used.

Examples of such inorganic nucleating agents include wollastonite, xonotolite, borate stone, potassium magnesium hydrogen carbonate, calcium metasilicate (α), calcium metasilicate (β) manganese metasilicate, calcium sulfate, cerium sulfate. Examples include (III), zinc phosphate, zinc dihydrogen phosphate, calcium dihydrogen phosphate, aluminum aluminosilicate, and potassium aluminosilicate.
Among these, wollastonite, calcium sulfate, and calcium metasilicate are preferable from the viewpoint of improving the degree of stereoization and transparency, and wollastonite, calcium metasilicate (α), and the like are preferable.
Of these, wollastonite, calcium sulfate, and calcium metasilicate are preferable from the viewpoint of improving the degree of stereoization and fastness to dyeing, and wollastonite, calcium metasilicate (α) and the like are preferable.

Preferable examples of the phosphoric acid ester metal salt used in the present invention include aromatic organic phosphoric acid ester metal salts represented by the following formulas (3) and (4).
Aromatic organic phosphoric acid ester metal salts can be used in combination of one kind, a plurality of kinds or those containing various agents.

In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and M ₁ represents an alkali. A metal atom, an alkaline earth metal atom, a zinc atom or an aluminum atom; p represents 1 or 2; q is 0 when M ₁ is an alkali metal atom, an alkaline earth metal atom or a zinc atom; Represents 1 or 2.

Wherein R ₄ , R ₅ and R ₆ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, M ₂ represents an alkali metal atom, an alkaline earth metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, q represents 0 when M ₂ is an alkali metal atom, alkaline earth metal atom or zinc atom, and 1 or 2 when M ₂ is an aluminum atom. The aromatic organic phosphoric acid ester metal salt can be used alone or in combination.
In Formula (3), R ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms represented by R ₁ include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl and the like. R ₂ and R ₃ each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.
Examples of the alkyl group having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, amyl, tert-amyl, hexyl, heptyl, Examples include octyl, iso-octyl, tert-octyl, 2-ethylhexyl, nonyl, iso-nonyl, decyl, iso-decyl, tert-decyl, undecyl, dodecyl, tert-dodecyl group and the like.
M ₁ represents an alkali metal atom such as Na, K or Li, an alkaline earth metal atom such as Mg or Ca, a zinc atom or an aluminum atom. p represents 1 or 2, q represents 0 when M ₁ is an alkali metal atom, alkaline earth metal atom or zinc atom, and 1 or 2 when M ₁ is an aluminum atom.
Preferred examples of the phosphoric acid ester metal salt represented by the formula (3) include those in which R ₁ is a hydrogen atom, and R ₂ and R ₃ are both tert-butyl groups.

In the formula (4), R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group having 1 to 12 carbon atoms represented by R ₄ , R ₅ and R ₆ include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl and tert-butyl. , Amyl, tert-amyl, hexyl, heptyl, octyl, iso-octyl, tert-octyl, 2-ethylhexyl, nonyl, iso-nonyl, decyl, iso-decyl, tert-decyl, undecyl, dodecyl, tert-dodecyl, etc. Can be mentioned.
M ₂ represents an alkali metal atom such as Na, K or Li, an alkaline earth metal atom such as Mg or Ca, a zinc atom or an aluminum atom. p represents 1 or 2, q represents 0 when M ₂ is an alkali metal atom, alkaline earth metal atom or zinc atom, and 1 or 2 when M ₂ is an aluminum atom.
Preferred examples of the phosphoric acid ester metal salt represented by the formula (4) include, for example, those in which R ₄ and R ₆ are methyl groups and R ₅ is tert-butyl group.

Among the phosphoric acid ester metal salts, those commercially available, for example, trade names manufactured by Asahi Denka Co., Ltd., ADK STAB NA-10, NA-11, Na-21, NA-30, NA-35, etc. are also used in the phosphoric acid ester of the present invention. It can be effectively used as a metal salt for a desired purpose. Among these, Na-21 containing a phosphoric acid ester aluminum salt and an organic auxiliary is exemplified as a preferable product from the viewpoint of fiber properties among molded articles.
The amount of the crystallization nucleating agent used is in the range of 0.01 to 5 parts by weight per 100 parts by weight of the composition (A). If the amount is less than 0.01 parts by weight, the desired effect is hardly observed or is too small for practical use. On the other hand, if it is used in an amount of more than 5 parts by weight, it is not preferable since it may cause thermal decomposition or deterioration coloring when forming a molded product.
Accordingly, the range of 0.05 to 4 parts by weight is preferably selected, and the range of 0.1 to 3 parts by weight is particularly preferably selected.

The crystal nucleating agent used in the present invention preferably has a particle size as small as possible, particularly a small content ratio of large particles exceeding 10 μm from the viewpoint of moldability and transparency of a polylactic acid molded product. The thing of 0.01-10 micrometers is used suitably. More preferably 0.05 to 7 μm is selected. When the content ratio of large particles exceeding 10 μm exceeds 20%, the defect ratio of the polylactic acid molded product increases, which is not preferable.
A crystal nucleating agent having such a particle size can be easily obtained by pulverizing a commercially available crystal nucleating agent with a ball mill, sand mill, hammark crusher, or atomizer and classifying it with various classifiers. It is industrially difficult to make the particle size of the crystal nucleating agent smaller than 0.01 μm, and it is not necessary to make it very small practically. However, if the content ratio of the particles having a particle size larger or larger than 10 μm is high, the problem of increasing the defect rate of the molded product increases, which is not preferable.

The composition (A) and molded article of the present invention preferably have a carboxy end group concentration of 0.1 to 60 equivalents / ton. More preferably, it is 0.1-40 equivalent / ton, More preferably, it is 0.2-20 equivalent / ton, Most preferably, it is the range of 0.3-10 equivalent / ton.
If a carboxy group is present beyond this range, the durability of the resin composition or molded product under wet heat conditions or melt stability will be deteriorated, and the resin will deteriorate and the molecular weight will decrease during use or melt molding. Or coloring may occur, which is not preferable. Further, even if the carboxy group is lowered below the above range, the above-described improvement in wet heat stability and melt stability is often not improved so as to be practically meaningful.

In order to adjust the carboxy group concentration of the composition (A) and the molded article to 0.1 to 60 equivalent / ton, it is also possible to use polylactic acid (B) or (C) having a reduced carboxy group concentration by solid phase polymerization. Although it is a preferred embodiment, it is preferable to apply a carboxy group blocking agent in the present invention. A combination of both is also a preferred embodiment.
Carboxy group capping agent not only seals the carboxy terminal group of polylactic acid resin, but also low molecular weight compounds such as carboxy group and lactide, lactic acid, formic acid, pyruvic acid generated by decomposition reaction of polylactic acid resin and various additives There is also an advantage that the carboxy group can be sealed to stabilize the resin.
Furthermore, the acidic low molecular weight compound also has an advantage of preventing a hydroxyl group terminal produced by decomposing polylactic acid or moisture entering the resin composition.

As such a carboxy group blocking agent, it is preferable to use at least one compound selected from conventionally known carbodiimide compounds, epoxy compounds, oxazoline compounds, oxazine compounds, isocyanate compounds, and carbodiimide compounds, epoxy compounds, oxazoline compounds. An isocyanate compound is exemplified as a preferable one.
Of these, carbodiimide compounds can be preferably used. The carbodiimide compound used in the present invention is a compound having one or more carbodiimide groups in the molecule, preferably 0.1 to 5% by weight of isocyanate groups, and a carbodiimide equivalent of 200 to 500.
When a small amount of an isocyanate group is present in the carbodiimide compound, not only the effect of the combined use of the isocyanate compound appears, but also the presence of the carbodiimide group and the isocyanate group more closely exhibits a further effect in improving wet heat durability.
Moreover, as a carbodiimide compound, a commercially available polycarbodiimide compound can be suitably used without the need to synthesize. Examples of such commercially available polycarbodiimide compounds include Carbodilite LA-1 and HMV-8CA sold under the trade name of Carbodilite sold by Nisshinbo Co., Ltd.

In the present invention, the amount of the carboxy group blocking agent used is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight per 100 parts by weight of the composition (A). In the present invention, sulfone is used during film casting. By applying the acid quaternary phosphonium salt to the composition (A), the adhesion to the cooling roll by the electrostatic adhesion method is improved at the time of melt extrusion, and the flatness and thickness uniformity of the film are improved, and pin-like defects, etc. Thus, the hue can be improved.

  In the present invention, as the sulfonic acid quaternary phosphonium salt, for example, a compound represented by the formula (5) and a compound represented by the formula (6) can be preferably used.

In the formula, n is 1 or 2, X ¹ and X ² are the same or different hydrogen atoms or ester-forming functional groups, and A ¹ is an (n + 2) -valent C 2-18 fatty acid. R ¹ , R ² , R ³ , and R ⁴ may be the same or different, an alkyl group having 1 to 18 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, and 6 to 6 carbon atoms. 12 aryl groups. However, X ¹ and X ² are not simultaneously hydrogen atoms.

In the formula, m is 1 or 2, A ² is an m-valent aliphatic group or aromatic group having 4 to 18 carbon atoms, and R ⁵ , R ⁶ , R ⁷ , and R ⁸ are the same or different. Or a monovalent hydrocarbon group having 1 to 18 carbon atoms.
In the above formula (5), X ¹ and X ² are hydrogen atoms or ester-forming functional groups which may be the same or different. Examples of the ester-forming functional group include a carboxyl group, an alkoxycarbonyl group, and a hydroxyl group. However, X ¹ and X ² are not simultaneously hydrogen atoms. R ¹ , R ² , R ³ and R ⁴ may be the same or different and each represents an alkyl group having 1 to 18 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms.

The alkyl group having 1 to 18 carbon atoms may be linear or branched. Specifically, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n- Examples include decyl, n-undecyl, n-dodecyl, n-pentadecyl, and n-octadecyl group.
Examples of the aralkyl group having 7 to 12 carbon atoms include benzyl, 2, -methylbenzyl, 4-methylbenzyl, 2,4-dimethylbenzyl, 4-ethylbenzyl group and the like. Examples of the aryl group having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, 2-methylphenyl, 4-methylphenyl, 2,4-dimethylphenyl, naphthyl, and biphenyl groups.
n is 1 or 2. A ¹ is an (n + 2) valence, that is, a trivalent or tetravalent aliphatic group having 2 to 18 carbon atoms or an aromatic group. Specific examples of A ¹ will be apparent from the specific examples of the compound of formula (1) described below.

Among such quaternary phosphonium sulfonates, the sulfonic acid quaternary phosphonium salt represented by the above formula (5) is preferable because of good adhesion to the cooling drum, and 3,5-carboxybenzene-4-sulfonic acid tetrabutylphosphonate is particularly preferable. preferable.
In addition, although sulfonic acid quaternary phosphonium salt can also be used only by 1 type, in order to achieve desired objectives, such as heat resistance of a film, lubricity, and transparency, it is also a preferable usage method to use together 2 or more types. is there.
The content of the sulfonic acid quaternary phosphonium salt is preferably 0.003 to 0.5% by weight, more preferably 0.005 to 0.1% by weight. If this ratio is less than 0.003% by weight, the adhesion between the polylactic acid film and the cooling drum becomes insufficient, and the object cannot be achieved. If this ratio exceeds 0.5% by weight, the dispersibility of the sulfonic acid quaternary phosphonium salt in the polylactic acid is deteriorated, and fish eyes are generated in the film, or the sulfonic acid quaternary phosphonium salt is formed during melt film formation. The thermal decomposition of polylactic acid and the thermal decomposition of polylactic acid become remarkable, and the coloring of the film becomes remarkable.

Furthermore, in the film of the present invention, it is also a preferred embodiment that a lubricant is applied to the composition (A) for the purpose of improving film winding and running performance, as long as the object of the present invention is not violated.
In the composition (A) of the present invention, if desired, a thermoplastic resin other than polylactic acid, a thermosetting resin, a soft thermoplastic resin, an impact resistance improver, a crystallization accelerator, as long as it does not contradict the spirit of the present invention. Crystallization nucleating agent, film-forming property improver by electrostatic adhesion method, plasticizer, lubricant, organic and inorganic lubricants, organic and inorganic fillers, phenolic, phosphorus and sulfur antioxidants, thermal stability Agent, light stabilizer, ultraviolet absorber, heat stabilizer, mold release agent, antifogging agent, antistatic agent, flame retardant, impact resistance enhancer, foaming agent, antibacterial and antifungal agent, organic and inorganic dyes, One kind or two or more kinds of coloring agents including pigments, synthetic polymers such as natural or polyamide, polycarbonate, polyacetal, polybutylene terephthalate, and ABS can be contained.

In order to apply the above-mentioned additive to the composition (A) of the present invention, it can be applied by blending the agent at an arbitrary stage between the start of polymerization of polylactic acid and before melt molding.
When an agent is added between the start and the end of the polymerization, the agent-containing polylactic acid can be produced by using a normal agent charging method.
Moreover, conventionally well-known various methods can be used suitably for adding an agent to polylactic acid. For example, a method of mixing polylactic acid and a phosphoric acid ester metal salt with a tumbler, V-type blender, super mixer, Nauta mixer Banbury mixer, kneading roll, uniaxial or biaxial extruder, etc. is suitably used. Such polylactic acid (B) The composition (A) comprising (C) can be melt-molded as it is, but it is also one of preferred embodiments that it is solidified and pelletized and then molded. The shape of the pellet is preferably one having a shape suitable for molding the pellet by various molding methods, specifically, the pellet length is about 1 to 7 mm, the major axis is about 3 to 5 mm, and the minor axis is about 1 to 4 mm. In addition, the pellet shape is preferably one with little variation.

<Molded product>
The composition (A) of the present invention comprises a conventionally known injection molding method, gas-assisted injection molding method, Push-Pull injection molding method, SP mold method, gate seal method, hollow injection molding method, extrusion molding method, blow molding method. , Injection blow molding, rotational molding, stampable molding, vacuum molding, compression molding, calendar molding, compressed air. Various molded products can be processed by methods such as vacuum forming, thermal processing, cold processing, and inflation molding.
At the time of injection molding, the mold temperature is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, and more preferably 70 ° C. or higher from the viewpoint of increasing the crystallization of the molded product and the molding cycle. However, in order to prevent deformation of the product, it is necessary to set it to 140 ° C. or lower. More preferably, 120 ° C. or lower, particularly preferably 110 ° C. or lower is selected. It is practically preferable to set an appropriate temperature in consideration of the characteristics of the device used in such a temperature range.
The molded article is composed of the composition (A) and preferably satisfies the following requirements (d) to (f) at the same time.
(D) The weight average molecular weight is 80,000 or more and 500,000 or less.
(E) The undissolved content when dissolved in E-sol is 0.1% by weight or less based on the composition (A).
(F) The wavelength of 400 nm to 700 nm average light transmittance of a molded product having a thickness of 1 mm is 80% or more.

The molded article preferably has a stereogenicity (S) measured by DSC of 80% or more and a crystallinity (Cr) of 30% to 60%. However, crystallinity (Cr) is represented by the following formula (2).
Cr = (ΔHmsc / 142) × 100 (2)
In the formula, ΔHmcs represents the heat of crystal melting (J / g) of the melting peak at 190 ° C. or higher in DSC measurement.

OA equipment housings and chassis such as personal computers, word processors, fax machines, copiers, printers, CD-ROM trays, turntables, pickup chassis, various gears, TVs, videos, electric washing machines, Housing and parts for household appliances such as electric dryers and electric vacuum cleaners, electric tools such as electric saws and electric drills, telescope barrels, microscope barrels, camera bodies, camera housings, optical instrument parts such as camera barrels, Automotive parts such as door handles, pillars, bumpers, and instrument panels can be suitably manufactured. In particular, injection molded products such as automobile parts (outer door handles, inner door handles, etc.) and machine parts (electric tool covers, etc.) that require mechanical strength, chemical resistance, wet heat fatigue, etc., extrusion molded products, vacuum compressed air Suitable for molded products.
Also blow molded products such as bottles, packaging films, condenser films (for example, films with a thickness of 3 μm or less), printer ribbon films (for example, films with a thickness of about 5 μm), heat-sensitive stencil printing films, magnetic recording films (for example, QIC) For tape: 1/4 inch tape for computer recording), Montglare film, polarizing plate protective film, antireflection film, antiglare film and other films, sheets, non-woven fabric, fiber, crimped yarn, and these fibers Fabrics, composites with other materials, agricultural materials, fishery materials, civil engineering / architectural materials, stationery, medical supplies or other molded articles can be obtained, and molding can be carried out by conventional methods.

<Film>
The film can be produced by melt-extruding the composition (A) from a die. The temperature (° C.) of the composition (A) at the time of melt extrusion is preferably in the range of Tmsc to (Tmsc + 100) (where Tmsc is the temperature of the crystal melting peak of 190 ° C. or more (° C.) in DSC measurement). Represents). The temperature of the composition (A) at the time of melt extrusion is preferably 240 to 300 ° C, more preferably 245 to 280 ° C, and particularly preferably 250 to 275 ° C, where flow spots are not easily generated.
The melt extrusion is preferably carried out by extruding the composition (A) from a die onto a cooling drum, closely contacting the film with a rotating cooling drum, and cooling.
At the time of film casting, it is preferable to cool and solidify with a cooling drum while applying an electrostatic charge from an electrode by an electrostatic contact method. At this time, the electrode to which an electrostatic charge is applied preferably has a wire shape or a knife shape.
The surface material of the electrode is preferably platinum. That is, when film formation is continued for a long time, there is a concern that impurities that sublimate from the film may adhere to the electrode surface or the electrode surface may be deteriorated, thereby reducing the ability to apply static electricity. It is possible to prevent adhesion of impurities by spraying in the vicinity thereof and installing an exhaust nozzle above the electrode. Moreover, the said problem can be prevented more efficiently by using platinum as an electrode surface material and keeping a discharge electrode at 170-350 degreeC.
The composition (A) to be supplied to the extruder is preferably dried before being supplied to the extruder in order to suppress decomposition during melting. The water content is particularly preferably 100 ppm or less. The composition (A) may contain the above-described crystallization nucleating agent, carboxy group blocking agent, sulfonic acid quaternary phosphonium salt, lubricant, and the like, if desired.

The obtained unstretched film can be further stretched in a uniaxial direction or a biaxial direction as necessary to obtain a uniaxially stretched film or a biaxially stretched film. In order to obtain such a uniaxially stretched film or a biaxially stretched film, the unstretched film is heated to a temperature at which the unstretched film can be stretched, that is, a glass transition temperature of polylactic acid (hereinafter sometimes referred to as Tg) to a temperature of Tg + 80 ° C. or less. , Stretching at least in the uniaxial direction.
The stretching ratio is selected in the range of 2 to 12 times for a uniaxially stretched film and 5 to 50 times for the stretched area ratio of a biaxially stretched film. A biaxially stretched film is manufactured by, for example, a longitudinal-transverse sequential stretching method in which an unstretched film is first stretched in the longitudinal direction and then stretched in the transverse direction, and simultaneously in the longitudinal and transverse directions, the axial stretching method is simultaneously performed. Can do. This biaxially stretched film can be further restretched in the longitudinal direction or the uniaxial direction of the lateral direction, or in the biaxial direction of the longitudinal direction and the lateral direction to form a biaxially restretched film.

The uniaxially stretched film or the biaxially stretched film is preferably heat-treated after the stretching treatment. Heat treatment is preferably performed at a temperature equal to or lower than the crystal melting peak temperature (Tmsc) of the composition (A). Moreover, by heat-treating in the range of Tmh to Tmsc of the composition (A), the film is less broken, the heat setting effect is sufficiently increased, and a film having good dimensional stability can be obtained. Here, Tmh represents the temperature (° C.) of the crystal melting peak below 190 ° C. in DSC measurement. Tmsc represents a crystal melting peak temperature (° C.) of 190 ° C. or higher in DSC measurement.
That is, the film can be produced by uniaxially or biaxially stretching an unstretched film obtained by melt extrusion, and then heat-treating at a temperature (° C.) of Tmh to Tmsc.
The uniaxially stretched film or the biaxially stretched film thus obtained is subjected to a surface activation treatment by a conventionally known method if desired, for example, in accordance with the method described in JP-B-56-18181 and JP-B-57-30854. For example, plasma treatment, amine treatment, and corona treatment can be performed.

  The film of the present invention preferably has an average light transmittance of 90% or more at a wavelength of 400 nm to 700 nm at a thickness of 50 μm. The film of the present invention is a film obtained by melt-extruding the composition (A) from a die, and the temperature (° C.) of the composition (A) at the time of melt-extrusion is preferably Tmsc to (Tmsc + 100). The film of the present invention is preferably obtained by heat treatment in a temperature range of Tmh to Tmsc after uniaxial or biaxial stretching.

  Films with little E-sol insoluble foreign matter, good transparency and good heat resistance of the present invention include packaging films, condenser films (for example, films having a thickness of 3 μm or less), and printer ribbon films (for example, thickness of about 5 μm). Film), heat-sensitive stencil printing film, magnetic recording film (for example, for QIC tape: 1/4 inch tape for computer recording), and Montglare film (for example, film having a thickness of 50 μm or less). The film of the present invention is suitable for a packaging film and an optical film. In particular, a film having a haze of 1% or less is useful for optical applications.

As an optical film, it can be used for a protective film for a polarizing plate, an antireflection film, an antiglare film and the like. A polylactic acid film has a characteristic that the optical elastic modulus is low. For example, since a change in optical characteristics due to a stress applied to an edge of a large area liquid crystal screen is small, a uniform screen can be obtained. Furthermore, when a polylactic acid film is used as a protective film for the polarizing plate, the optical properties can be stably obtained by keeping the birefringence low.
Further, as a strength of stereocomplex polylactic acid, the refractive index tends to hardly change depending on the draw ratio, so that there is a merit that retardation spots due to stretch spots hardly occur.
Further, due to its water vapor permeability, polyvinyl alcohol (PVA), which is an aqueous casting film, can be sufficiently dried, and can be used as an alternative to triacetyl cellulose (TAC). By using stereocomplex polylactic acid, the heat and moisture resistance is improved and improved.
In addition, when used as a packaging film for food, not only the contents are visible, but also the high melting point of stereocomplex polylactic acid enables heat sterilization and heating in a microwave oven, etc. Benefits come out.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention does not receive any limitation by this. Each value in the examples was determined by the following method.
(1) Weight average molecular weight (Mw) and number average molecular weight (Mn):
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined by comparison with a polystyrene standard sample by gel permeation chromatography (GPC). Use the following GPC measuring instrument, use chloroform eluent, flow at a column temperature of 40 ° C. and a flow rate of 1.0 ml / min, and inject 10 μl of a sample with a concentration of 1 mg / ml (chloroform containing 1% hexafluoroisopropanol). It was measured.
Detector: Differential refractometer RID-6A manufactured by Shimadzu Corporation
Pump: LC-9A manufactured by Shimadzu Corporation
Column: Tosoh Corporation TSKgelG3000HXL, TSKgelG4000HXL, TSKgelG5000HXL and TSKguardcocumHXL-L are connected in series.

(2) Crystal melting peak temperature, crystal melting heat, stereogenicity and crystallinity:
The following measurements were performed using a DCS7 differential scanning calorimeter (DSC) manufactured by PerkinElmer Co., Ltd. A 10 mg sample was heated from 30 ° C. to 250 ° C. at a temperature increase rate of 20 ° C./min in a 1st RUN under a nitrogen atmosphere, and the low temperature crystal melting peak temperature (Tmh, ° C.) and the high temperature crystal melting peak temperature (Tmsc, ° C. ), Low-temperature crystal melting heat (ΔHmh (J / g)) and high-temperature crystal melting heat (ΔHms (J / g)).
The stereoification ratio (S) is calculated from the following formula (1) from the heat of melting at a low temperature phase of 190 ° C. or lower (ΔHmh (J / g)) and the heat of melting at a high temperature phase of 190 ° C. or higher (ΔHmsc (J / g)). ).
S = ΔHmsc / (ΔHmh + ΔHmsc) × 100 (%) (1)
The crystallinity (Cr) was determined by the following formula (2).
Cr = (ΔHmsc / 142) × 100 (2)
(In the formula, 142 (J / g) is the heat of crystal fusion of the stereocomplex polylactic acid perfect crystal.)

(3) E-sol insoluble matter:
10 mg of sample was E-sol; [tetrachloroethane / phenol = (6/4) wt mixed solvent] dissolved in 1000 mL at 35 ° C. for 1 hr, Teflon (registered trademark) filter film sold by Asahi Seisakusho (average hole diameter 25 The residue was washed with chloroform and dried, and the weight of E-ol insoluble matter was measured with a precision balance.
(4) Melt stability (%):
The retention rate of reduced viscosity after holding the sample at 260 ° C. for 10 minutes in a nitrogen atmosphere was measured. When the polylactic acid resin (A) was formed into a film, if the melt stability was 80% or more, normal melt pressing could be performed without any problem, and it was determined that the melt stability passed.
(5) Measurement of reduced viscosity (η _sp / c):
The reduced viscosity was measured by dissolving 1.2 mg of a sample in 100 ml of E-sol and using an Ubbelohde viscosity tube at 35 ° C.
(6) Wet heat stability (%):
The sample was held at 80 ° C. and 90% RH for 11 hr, and the retention rate (%) of the reduced viscosity (η _sp / c) was measured and used as a wet heat stability and durability parameter. When the parameter was 80% or more, the polylactic acid resin assembled film could be stably used under normal wet heat conditions, and the durability was determined to be acceptable. If it was 90% or more, it was judged to be particularly good.

(7) Pellet hue;
The color L / b value of the pellet hue of the composition (A) was measured with a Z-1001DP color difference meter manufactured by Nippon Denshoku Co., Ltd. A larger color b value indicates a worse hue. Pellets with a color b value of more than 10 were judged unsuitable for commercial use.
(8) Formability A molded piece for ASTM measurement having a thickness of 3 mm was molded into 100 shots with a neomat N150 / 75 injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. at a cylinder temperature of 260 ° C., a mold temperature of 60 ° C., and a molding cycle of 150 seconds. The final 10-shot molded product was visually checked for distortion and the presence or absence of black foreign matter. Runs with no distortion or black foreign matter were accepted (OK), and runs with obvious distortion or black foreign matter were rejected (x). Runs with minute foreign matter and fine distortion were put on hold (Δ). The composition (A) that failed in moldability was judged to be unsuitable for industrial use.
(9) Light transmittance of molded product A molded plate having a thickness of 1 mm was prepared in the same manner as the moldability evaluation, and light having a wavelength of 400 nm to 800 nm was measured using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation). The transmittance was measured, the average value was taken as the light transmittance, and pass / fail was determined as follows.
Pass: When the light transmittance is 80% or more and the difference in light transmittance between 450 nm and 750 nm is 10% or less.
Fail (x): When the above conditions are not satisfied.

(10) Light transmittance of film Using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation), the light transmittance from a wavelength of 400 nm to 800 nm is measured, and the average value is regarded as the light transmittance, and the light transmittance is 90%. When it was above, it passed and less than 90% was determined to be unacceptable (x).
(11) Heat resistance of molded product A crystallized molded plate for moldability evaluation is measured in accordance with ASTM D648 (0.45 Ma), the heat distortion temperature is measured, a sample of less than 110 ° C is rejected by heat resistance, 110 ° C or more The sample was judged to be heat resistant.
(12) Heat resistance of film A film having a thickness of 15 microns was determined by a heat shrinkage rate of 150 ° C. A sample having a shrinkage rate of more than 5% or a melted sample was judged to have failed heat resistance, and a sample having a shrinkage rate of less than 5% was judged to have passed heat resistance.

(Synthesis example 1-1) Synthesis | combination of poly L-lactic acid Full-blade equipped vertical stirring tank (40L) equipped with vacuum piping, nitrogen gas piping, catalyst, L-lactide solution addition piping, and alcohol initiator addition piping is nitrogen. After the substitution, 30 kg of L-lactide, 0.90 kg of stearyl alcohol (0.030 mol / kg), 6.14 g of tin octylate (5.05 × 10 −4 mol / 1 kg) were charged, and the atmosphere had a nitrogen pressure of 106.4 kPa. Then, when the temperature was raised to 150 ° C. and the contents were dissolved, stirring was started, and the internal temperature was further raised to 190 ° C. When the internal temperature exceeded 180 ° C, the reaction started, so cooling was started, the internal temperature was maintained at 185 ° C to 190 ° C, and the reaction was continued for 1 hour. While further stirring, the reaction was carried out at a nitrogen pressure of 106.4 kPa and an internal temperature of 200 ° C. to 210 ° C. for 1 hour, and then a phosphorus deactivator was added and stirring was continued for 10 minutes. Stirring was stopped and air bubbles were removed by standing still for 20 minutes, and then the internal pressure was increased from 2 to 3 atm with nitrogen pressure, and the prepolymer was extruded into a chip cutter, and the weight average molecular weight was 120,000 and the molecular weight dispersion was 1.8. The prepolymer was pelletized.
Further, the pellets were dissolved by an extruder and charged into a non-axial vertical reactor at 15 kg / hr, and the pressure was reduced to 1.03 kPa to reduce the remaining lactide, which was chipped again to obtain poly L-lactic acid. The obtained poly L-lactic acid had a weight average molecular weight of 13,000, a molecular weight dispersion of 1.8, a carboxy group concentration, 30 equivalents / ton, and a low molecular weight compound content of 0.05% by weight.
(Synthesis Example 1-2) Synthesis of poly-D-lactic acid In Synthesis Example 1, D-lactide was used instead of L-lactide, and the weight average molecular weight was 14,000, the molecular weight dispersion was 1.8, the carboxy group concentration was 32 equivalents. / Ton, poly D-lactic acid having a low molecular weight compound content of 0.03% by weight was obtained.

(Synthesis Example 2-1) Synthesis of poly-L-lactic acid The same as Synthesis Example 1 except that the initiator stearyl alcohol was changed to the amount shown in Table 1 and the reaction time at an internal temperature of 200 ° C to 210 ° C was changed to 3 hours. Operation was performed to synthesize poly-L-lactic acid. The obtained poly L-lactic acid had a weight average molecular weight of 72,000, a molecular weight dispersion of 1.3, a carboxy group concentration of 32 equivalents / ton, and a content of a low molecular weight compound of 0.031% by weight.
(Synthesis Example 2-2) Synthesis of poly-D-lactic acid Poly-D-lactic acid was synthesized by using D-lactide instead of L-lactide in Synthesis Example 2-1. The obtained poly-D-lactic acid had a weight average molecular weight of 65,000, a molecular weight dispersion of 1.4, a carboxy group concentration of 32 equivalents / ton, and a low molecular weight compound content of 0.033% by weight.

(Synthesis Example 3-1) Synthesis of Poly L-lactic acid The polylactic acid prepolymer produced in Synthesis Example 1-1 was subjected to solid phase polymerization at 150 ° C. to 220 ° C. to produce poly L-lactic acid. The obtained poly L-lactic acid had a weight average molecular weight of 550,000, a carboxy group concentration of 10 equivalents / ton, and a low molecular weight content of 0.03%.
(Synthesis Example 3-2) Synthesis of Poly-D-lactic acid The polylactic acid prepolymer produced in Synthesis Example 1-2 was solid-phase polymerized at 150 ° C. to 220 ° C. to produce poly-D-lactic acid. The resulting poly D-lactic acid had a weight average molecular weight of 560,000, a carboxy group concentration of 10 equivalents / ton, and a low molecular weight content of 0.03%.

Example 1
The poly L-lactic acid produced in Synthesis Example 1-1 and the poly D-lactic acid produced in Synthesis Example 1-2 were mixed at a weight ratio of 1/1 and dried at 120 ° C. for 5 hours. Thereafter, 0.3% by weight of Nisshinbo Carbodilite LA-1 as a carboxy group sealant is added to the mixture, and the melt kneading zone from the raw material supply tank is made a nitrogen gas atmosphere having an oxygen gas partial pressure of 50 ppm or less. The mixture was melt-kneaded with a high-quality chromium-plated SUS316 twin-screw kneader at a cylinder temperature of 280 ° C. and a residence time of 5 minutes, and pelletized with a chip cutter to produce pellets of the composition (A) over 5 hours. The obtained sample at 5 hours was analyzed, and the results are shown in Table 1.
The E-sol insoluble content of the composition (A) was 0.01% by weight or less, and heat resistance, moldability, and hue were good.

(Comparative Example 1)
In Example 1, the nitrogen gas atmosphere condition was changed to the air atmosphere condition to produce a composition (A). The results are shown in Table 1.
(Comparative Example 2)
In Example 1, the composition (A) was produced under the same conditions except that only the cylinder temperature was changed to 240 ° C. The degree of stereoization was 76%. The results are listed in Table 1.
(Comparative Example 3)
A composition (A) was produced in the same manner as in Example 1, using the poly L-lactic acid produced in Synthesis Example 3-1 and the poly D-lactic acid produced in Synthesis Example 3-2. The results are shown in Table 1. The resulting composition was rejected with an E-sol insoluble content of 0.15% by weight. Further, the polymer hue and the color b value were 12 and the yellowish color was strong.

(Example 2)
In Example 1, as a crystallization nucleating agent in addition to the carboxy sealing agent, a phosphate ester metal salt having an average particle size of 0.1 μm or less (manufactured by Asahi Denki Kagaku Kogyo Co., Ltd., NA-21 crushed) The composition was prepared under the same conditions. The stereogenicity of the composition was 100%, and the E-sol insoluble content was 0.01% by weight or less. The results are shown in Table 1.

(Examples 3 and 4, Comparative Examples 4 to 6)
The compositions of Examples 1 and 2 and Comparative Examples 1 to 3 were molded and their moldability was evaluated. Moreover, heat resistance and light transmittance were evaluated using the same sample. The results are shown in Table 2.

(Example 5)
After drying 100 parts by weight of the pellets of the composition (A) produced in Example 1 at 120 ° C. for 5 hours, an average particle size of 0.1 μm or less obtained by pulverizing phosphate metal salt Na21 manufactured by Asahi Denki Kagaku Kogyo Co., Ltd. The mixture was melt kneaded with a twin screw extruder containing 0.2 part by weight. The obtained melt-kneaded material was melt extruded into a 210 μm film at a die temperature of 260 ° C. at a casting speed of 40 m / min, and was brought into close contact with the surface of the mirror-cooled drum by an electrostatic casting method using a platinum-coated linear electrode. . The obtained unstretched film was stretched 3.6 times in the longitudinal direction and 3.9 times in the transverse direction at 120 ° C. and heat-set at 180 ° C. to obtain a biaxially stretched film having a thickness of 15 μm. The properties of the obtained film are shown in Table 3. The E-sol insoluble matter was 0.01% by weight or less, and the light transmittance and heat resistance were acceptable.
(Comparative Examples 7-9)
The compositions of Comparative Examples 1 to 3 were formed in the same manner as in Example 5. The results are shown in Table 3.

Claims (12)

It contains polylactic acid (B) containing 90 mol% or more of L-lactic acid units and polylactic acid (C) containing 90 mol% or more of D-lactic acid units, and the weight ratio of the former (B) / the latter (C) is The composition (A) which is 10/90 to 90/10 and satisfies the following requirements (a) to (c) at the same time.
(A) The weight average molecular weight is 80,000 to 500,000.
(B) The degree of stereoification (S) measured with a differential scanning calorimeter (DSC) is 80% or more.
Here, the degree of stereogenicity (S) is expressed by the following formula (1).
S = {ΔHmsc / (ΔHmsc + ΔHmh)} × 100 (1)
(In the formula, ΔHmh represents the heat of crystal melting (J / g) of the melting peak of less than 190 ° C. in DSC measurement. ΔHmcs is the heat of crystal melting (J / g of the melting peak of 190 ° C. or more in DSC measurement). )
(C) The undissolved content when the composition (A) is dissolved in E-sol is 0.1% by weight or less based on the composition (A). The composition (A) according to claim 1, comprising triclinic crystal particles and / or a phosphate metal salt as a crystallization nucleating agent. A molded article comprising the composition (A) according to claim 1 and simultaneously satisfying the following requirements (d) to (f).
(D) The weight average molecular weight is 80,000 to 500,000.
(E) The undissolved content when dissolved in E-sol is 0.1% by weight or less based on the composition (A).
(F) The wavelength 400 nm to 700 nm light transmittance of a molded product having a thickness of 1 mm is 80% or more. The molded article according to claim 3, wherein the degree of stereometry (S) measured by DSC is 80% or more and the degree of crystallinity (Cr) is 30% to 60%.
However, the crystallinity (Cr) is represented by the following formula (2).
Cr = (ΔHmsc / 142) × 100 (2)
(In the formula, ΔHmcs represents the heat of crystal fusion (J / g) of the melting peak at 190 ° C. or higher in DSC measurement.) The molded article according to claim 3, which is a film. The film according to claim 5, wherein the light transmittance at a wavelength of 400 nm to 700 nm at a thickness of 50 µm is 90% or more. The film according to claim 5, which is a film obtained by melt-extruding the composition (A) from a die, and the temperature (° C.) of the composition (A) at the time of melt-extrusion is Tmsc to (Tmsc + 100).
(Here, Tmsc represents the temperature (° C.) of the crystal melting peak at 190 ° C. or higher in DSC measurement.) The film according to claim 5, which is obtained by heat treatment in a temperature range of Tmh to Tmsc after uniaxial or biaxial stretching.
(Here, Tmh represents the temperature (° C.) of the crystal melting peak of less than 190 ° C. in DSC measurement. Tmsc represents the temperature (° C.) of the crystal melting peak of 190 ° C. or more in DSC measurement.) A method for producing a film, comprising melting and extruding the composition (A) from a die, wherein the temperature (° C.) of the composition (A) at the time of melt extrusion is in a range of Tmsc to (Tmsc + 100).
(Here, Tmsc represents the temperature (° C.) of the crystal melting peak at 190 ° C. or higher in DSC measurement.) The method for producing a film according to claim 9, wherein an unstretched film obtained by melt extrusion is uniaxially or biaxially stretched and then heat-treated at a temperature (° C.) of Tmh to Tmsc. (Here, Tmh represents the temperature (° C.) of the crystal melting peak of less than 190 ° C. in DSC measurement. Tmsc represents the temperature (° C.) of the crystal melting peak of 190 ° C. or more in DSC measurement.) An optical film comprising the composition (A) according to claim 1. A packaging film comprising the composition (A) according to claim 1.