JP2010083906A - Polylactic acid film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid film having high transparency and good heat resistance, and a method for producing it. <P>SOLUTION: This polylactic acid film is produced by melt-extruding a polylactic acid composition which is obtained by melt-mixing poly L-lactic acid and poly D-lactic acid. The film is characterized in that stereocomplex crystallinity (S) which is showed by following formula and measured using a differential scanning calorimeter (DSC measurement) is ≥90%: S=äΔHmsc/(ΔHmsc+ΔHmh)}×100 (1), wherein ΔHmh is enthalpy of fusion at a melting peak of a low melting point when a crystal-melting peak temperature obtained by the DSC measurement is <190°C, and ΔHmsc is enthalpy of fusion at a melting peak of a high melting point when a crystal-melting peak temperature obtained by the DSC measurement is ≥190°C, as well as a haze is ≤10%, and a change in the haze after 10 minute-heat treatment at 140°C is ≤5%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polylactic acid film excellent in transparency, heat resistance and moldability and a method for producing the same. The present invention further relates to an optical polylactic acid film, a packaging polylactic acid film, and a molding polylactic acid film.

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 these, polylactic acid has not only the possibility of being a substitute for petroleum-based resins, but also has characteristics such as transparency and low refractive index, and is expected to be used for applications.

  However, polylactic acid usually has a low melting point of about 160 ° C. and has a problem in heat resistance such as melting and deformation. In addition, the biodegradability and degradation under a moist heat environment proceed at a relatively fast rate and there are problems in stability of physical properties.

  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. Yes. (Patent Document 1 and Non-Patent Document 1) This stereocomplex polylactic acid has an extremely high melting point of 200 to 230 ° C. compared to poly L-lactic acid and poly D-lactic acid, and an interesting phenomenon showing high crystallinity has been discovered. Has been.

  This stereocomplex polylactic acid can be used in high-temperature processing and heat-resistant applications, and further improved in biodegradability and degradation under wet heat environments, and optical films and packaging films that take advantage of its transparency. Prolonged life expectancy is expected with highly transparent film.

  However, the stereocomplex polylactic acid is a composite composition of a poly L-lactic acid phase and a poly D-lactic acid phase (hereinafter sometimes referred to as a homo phase) and a stereo complex polylactic acid phase (hereinafter sometimes referred to as a complex phase). In DSC measurement, a low melting point crystal melting peak corresponding to a melting point of a normal phase crystal of 190 ° C. or lower and a high melting point crystal melting peak corresponding to a melting point of a complex phase crystal of 190 ° C. or higher are generally 2 The peak of the book is measured.

The polylactic acid film is formed by a method such as a melt extrusion method or a solution cast method, and the melt extrusion method is superior to the solution cast method in terms of productivity.
However, in the prior art, stereocomplex polylactic acid has (1) melt viscosity, (2) presence of crystal forms with different melting points as described above, (3) generation of bubbles by thermal decomposition, (4) crystal orientation, etc. The desired transparent film could not be obtained.

  In other words, when a stereocomplex polylactic acid having a high weight average molecular weight sufficient to form a film having practical strength and toughness is formed by melt extrusion, the melt viscosity is high. In addition to the unstretched film, streaky surface spots were generated not only in the unstretched film but also in the film after the stretching process, and it was difficult to obtain sufficient transparency by scattering the surface light.

  If the resin temperature is increased to reduce the melt viscosity, bubbles are generated due to the thermal decomposition of polylactic acid, which increases the possibility of haze deterioration due to an increase in internal haze, which is contrary to the purpose of obtaining a transparent film. May cause problems. In addition, when the molecular weight is reduced and the viscosity is lowered, the extruded film becomes brittle, and a problem that sufficient mechanical strength cannot be obtained is also encountered.

  In addition, when forming a melt-extruded film, it is necessary to dry the resin in advance in order to prevent hydrolysis.For example, when heat-drying in a hot air oven or the like, or when making a stereocomplex polylactic acid resin into a melt-extruded film, When passing through the melt preheating zone of the extruder, the stereocomplex polylactic acid crystallizes and a homophase crystal and a complex phase crystal grow.

  Both a low-melting-point homophase crystal and a high-melting-point complex phase crystal exist, and this mixture exists in two states with different flow characteristics even when melting and kneading are considered. As a result, a layer structure of a high melting point portion and a low melting point portion is generated, and flow spots are generated due to two-phase separation, causing light scattering, and it is difficult to obtain a uniform film with high transmittance.

  Furthermore, when the draw ratio of the polylactic acid film exceeds a specific range, transparency is deteriorated although it is a feature of stereocomplex polylactic acid. That is, in addition to the problem of low heat resistance when the draw ratio is low, the above-described crystallization proceeds at a relatively low temperature and the light transmittance deteriorates, and when the draw ratio is too high, the transparency deteriorates due to crystal orientation. was there.

JP 63-24014 A Macromolecules, 24, 5651 (1991).

The conventional polylactic acid film has low heat resistance, so the film may crack during molding such as press molding, vacuum molding, pressure molding, etc., and sufficient molding cannot be performed, and cracks and wrinkles may occur after molding. There was a problem that it occurred or the surface was not smooth.
In addition, in a film having a low degree of orientation crystallization, such as an unstretched film, it is easily whitened by heating, and even if it is transparent at room temperature, all or part of the film is whitened when subjected to a molding process including heating. There was a problem.

An object of the present invention is to propose a polylactic acid film that is excellent in transparency, heat resistance, and moldability, and that can maintain high transparency even when exposed to high temperatures, and a method for producing the film. .
A further object of the present invention is to propose an optical polylactic acid film, a packaging polylactic acid film and a molding polylactic acid film which are excellent in transparency, heat resistance and moldability.

  As a result of diligent research to solve the above problems, by using stereocomplex type polylactic acid as polylactic acid and controlling the flow in the extrusion process, whitening in a high temperature environment can be achieved even in an unstretched state. It was suppressed and high transparency was maintained, and it came to complete this invention.

That is, the present invention
1. A polylactic acid (B) component containing 0 to 10 mol% of a component other than the L-lactic acid unit as a main component, and a component other than the L-lactic acid unit as a main component and a component other than the D-lactic acid unit as 0 A polylactic acid film obtained by melt-extruding polylactic acid (A) obtained by melt-kneading a polylactic acid (C) component containing 10 mol% to 10 mol% in a weight ratio of (B / C) = 10/90 to 90/10 The change in haze after heat treatment at 140 ° C. for 10 minutes with a differential scanning calorimeter measurement (DSC measurement) and a stereocomplex crystallinity (S) of 90% or more, 10% or less, and the following formula: Polylactic acid film having 5% or less.
[Equation 1]
S = {ΔHmsc / (ΔHmsc + ΔHmh)} × 100 (1)
(In the formula, ΔHmh is the melting enthalpy of the low melting point melting peak temperature determined from DSC measurement of less than 190 ° C., and ΔHmsc is the high melting point of the crystal melting peak temperature calculated from DSC measurement of 190 ° C. or higher. Represents the melting enthalpy of the melting peak.)
2. The polylactic acid film according to 1, stretched uniaxially to less than 2.2 times.
3. 3. The polylactic acid film according to 1 or 2, which has been stretched to an area magnification of less than 4 times.
4). The polylactic acid film according to any one of 1 to 3, comprising triclinic inorganic particles (D) and / or a phosphate metal salt (E).
5). 5. The polylactic acid film according to any one of 1 to 4, wherein the carboxyl end group concentration is 0 to 10 eq / ton.
6). The polylactic acid film according to any one of 1 to 5, wherein the polylactic acid (A) has a weight average molecular weight of 80,000 to 250,000.
7). A polylactic acid (B) component containing 0 to 10 mol% of a component other than the L-lactic acid unit as a main component, and a component other than the D-lactic acid unit as a main component containing the D-lactic acid unit as 0 to 0 A polylactic acid (A) obtained by melt-kneading a polylactic acid (C) component containing 10 mol% in a weight ratio of (B / C) = 10/90 to 90/10 is a resin of polylactic acid (A) A method for producing a polylactic acid film, characterized in that melt extrusion is performed in a temperature range of (Tmsc + 20) to (Tmsc + 50) (° C.).
(Here, Tmsc represents the peak temperature of the high melting point crystal melting peak with a peak temperature of 190 ° C. or higher obtained from DSC measurement.)
8). 8. The production method according to 7, wherein the draft ratio is 2 or more and 80 or less.
9. 9. The production method according to 7 or 8, wherein after the melt extrusion, the film is not substantially stretched, is uniaxially stretched to less than 2 times, or is biaxially stretched to have a surface magnification of less than 4 times.
10. 7. The optical polylactic acid film according to any one of 1 to 6 above.
11. The polylactic acid film for packaging according to any one of 1 to 6 above.
12 7. The molding polylactic acid film according to any one of 1 to 6 above.

  The polylactic acid film of the present invention has good transparency, heat resistance, and moldability, and can maintain high transparency even when exposed to high temperatures. Therefore, the polylactic acid film of the present invention can be suitably used for optical applications, packaging applications, molding applications, and the like. Moreover, the polylactic acid film of this invention can be manufactured industrially with high efficiency.

The present invention is described in detail below.
The polylactic acid film of the present invention has an L-lactic acid unit as a main component, a polylactic acid (B) component containing 0 to 10 mol% of components other than the L-lactic acid unit, a D-lactic acid unit as a main component, and D -It consists of polylactic acid (A) formed by melt-kneading a polylactic acid (C) component containing 0 to 10 mol% of components other than lactic acid units.

The polylactic acid film of the present invention has a haze of 10% or less. A film whose haze exceeds 10% feels strongly cloudy and has poor transparency, which is outside the scope of the present invention.
In the present invention, the haze is preferably 8% or less, more preferably 5% or less, and particularly preferably 2% or less.
It is preferable that the optical polylactic acid film has high transparency, and the haze is preferably 1% or less.

  As described above, the haze is preferably as low as possible from the viewpoint of transparency. However, in order to reduce the haze, it is necessary to reduce the film thickness, and it is necessary to reduce the amount of addition of a lubricant, etc. It tends to be lower. Further, if the film thickness is reduced in order to increase transparency, the polylactic acid film for molding tends to be easily broken during molding. From such a viewpoint, the lower limit of haze is preferably 0.5% or more, and more preferably 3% or more.

  In addition, the polylactic acid film of the present invention has a change in haze ((haze after heat treatment) − (haze before heat treatment)) after heat treatment at 140 ° C. for 10 minutes of 5% or less. When this change is in the above numerical range, whitening after heat molding is suppressed in molding applications. From such a viewpoint, the change in haze is preferably 4% or less, more preferably 3% or less, and particularly preferably 1% or less.

  The film thickness of the polylactic acid film of the present invention is preferably 40 μm or more and 120 μm or less. When the film thickness is in the above numerical range, the handleability is excellent. In addition, it becomes easy to achieve the haze defined by the present invention. From such a viewpoint, the film thickness is more preferably 60 μm to 100 μm, and particularly preferably 70 μm to 90 μm.

  As the polylactic acid (B) component, polylactic acid substantially composed only of L-lactic acid units and copolymers with other monomers are shown. L-lactic acid is particularly preferred.

  The polylactic acid (B) component has an L-lactic acid unit of 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 98 to 100 mol%, from the viewpoint of physical properties such as crystallinity and heat resistance of the film. is there.

That is, copolymer component units other than D-lactic acid units and / or L-lactic acid units are 0 to 10 mol%, preferably 0 to 5 mol%, more preferably 0 to 2 mol%.
This polylactic acid (B) component has crystallinity, and its melting point is preferably 150 ° C. or higher and 190 ° C. or lower, and more preferably 160 ° C. or higher and 190 ° C. or lower.

  This is because, when the melting point falls within these ranges, when a stereocomplex polylactic acid is formed from the polylactic acid component, a stereocomplex crystal having a higher melting point can be formed and the crystallinity can be increased. .

  The polylactic acid (B) component used in the present invention preferably has a weight average molecular weight in the range of 80,000 to 250,000, and more preferably 100,000 to 250,000 or less. Particularly preferred is a range of 120,000 to 200,000.

  By using the polylactic acid (B) component having such a weight average molecular weight range, stereocomplex polylactic acid can be produced industrially and efficiently, and while suppressing the flow spots of polylactic acid (A), the present invention. This is because the transparency range of the polylactic acid film can be matched.

  As the polylactic acid (C) component, polylactic acid substantially composed only of D-lactic acid units and copolymers with other monomers are shown. Particularly preferred is D-lactic acid.

The polylactic acid (C) component has a D-lactic acid unit of 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 98 to 100 mol% from the viewpoint of physical properties such as crystallinity and heat resistance of the film. is there.
That is, the copolymer component unit other than L-lactic acid units and / or D-lactic acid is 0 to 10 mol%, preferably 0 to 5 mol%, more preferably 0 to 2 mol%.

This polylactic acid (C) component has crystallinity, and its melting point is preferably 150 ° C. or higher and 190 ° C. or lower, and more preferably 160 ° C. or higher and 190 ° C. or lower.
This is because, when the melting point falls within these ranges, when a stereocomplex polylactic acid is formed from the polylactic acid component, a stereocomplex crystal having a higher melting point can be formed and the crystallinity can be increased. .

  The polylactic acid (C) component used in the present invention preferably has a weight average molecular weight in the range of 80,000 to 250,000, more preferably 100,000 or more and 250,000 or less. Especially preferably, it is the range of 120,000 to 200,000.

  By using a polylactic acid (C) component having such a weight average molecular weight range, stereocomplex polylactic acid can be produced industrially and efficiently, while suppressing the flow group of polylactic acid (A). This is because the transparency range of the polylactic acid film can be matched.

  The polylactic acid (B) component and the polylactic acid (C) component used in the present invention can contain a copolymer component other than L-lactic acid and D-lactic acid, as long as the crystallinity is not impaired. The copolymer component is not particularly limited. For example, hydroxycarboxylic acids such as glycolic acid, caprolactone, butyrolactone, propiolactone, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-propanediol, 1,5-propanediol, hexane Diol, octanediol, decanediol, dodecanediol, aliphatic diols having 2 to 30 carbon atoms, succinic acid, maleic acid, adipic acid, aliphatic dicarboxylic acids having 2 to 30 carbon atoms, terephthalic acid, isophthalic acid, hydroxy One or more monomers selected from aromatic diols such as benzoic acid and hydroquinone, aromatic dicarboxylic acids and the like can be selected.

The method for producing the polylactic acid (B) component and the polylactic acid (C) component is not particularly limited, and a conventionally known method can be suitably used.
For example, a method of directly dehydrating condensation of L- or D-lactic acid, a method of solid-phase polymerization of L- or D-lactic acid oligomers, L- or D-lactic acid once dehydrating and cyclizing to lactide, and then melt ring-opening polymerization The method of doing is illustrated.

  Of these, polylactic acid obtained by a direct dehydration condensation method or a melt ring-opening polymerization method of lactides is preferable from the viewpoint of quality and production efficiency, and among them, a melt ring-opening polymerization method of lactides is most preferably selected.

  Any catalyst can be used as the catalyst used in these production methods as long as the polylactic acid (B) component and the polylactic acid (C) component can be polymerized so as to have the predetermined characteristics described above.

  That is, lactide melt-opening polymerization catalysts include alkali metals, alkaline earth metals, rare earths, transition metals, fatty acid salts such as aluminum, germanium, tin, and antimony, carbonates, sulfates, phosphates, oxides, water Oxides, halides, alcoholates and the like are well known.

  Among these, a catalyst containing at least one selected from tin, aluminum, zinc, calcium, titanium, germanium, manganese, magnesium and rare earth elements is preferable. Hereinafter, the catalyst may be abbreviated as a specific metal-containing catalyst.

Such specific metal-containing catalysts are conventionally known and exemplified as follows.
Stannous chloride, stannous bromide, stannous iodide, stannous sulfate, stannic oxide, tin myristate, tin octylate, tin stearate, tetraphenyltin, tin methoxide, tin ethoxide, tin Butoxide, aluminum oxide, aluminum acetylacetonate, aluminum isopropoxide, aluminum-imine complex titanium tetrachloride, ethyl titanate, butyl titanate, glycol titanate, titanium tetrabutoxide, zinc chloride, zinc oxide, diethyl zinc, trioxide Examples include antimony, antimony tribromide, antimony acetate, calcium oxide, germanium oxide, manganese oxide, manganese carbonate, manganese acetate, magnesium oxide, and yttrium alkoxide.

  Considering the catalytic activity and few side reactions, stannous chloride, stannous bromide, stannous iodide, stannous sulfate, stannic oxide, stannous myristate, stannous octoate, stannous stearate Preferred examples include tin-containing compounds such as tetraphenyltin, and aluminum-containing compounds such as aluminum acetylacetonate, aluminum butoxide, and aluminum-imine complexes. More preferably, the following are illustrated.

  Specifically, diethoxytin, dinonyloxytin, tin myristate, tin octylate, tin stearate, tin chloride, aluminum acetylacetonate, aluminum isopropoxide and the like are further exemplified.

The amount of the catalyst used is 0.42 × 10 ⁻⁴ to 100 × 10 ⁻⁴ (mol) per kg of lactide, and 1.68 × 10 ^{−4 in} consideration of reactivity, color tone and stability of the obtained polylactide. To 42.1 × 10 ⁻⁴ (mol), particularly preferably 2.53 × 10 ⁻⁴ to 16.8 × 10 ⁻⁴ (mol) mol.

  The polylactic acid (B) component and the polylactic acid (C) component are obtained by removing the polymerization catalyst by a conventionally known method, for example, by washing with a solvent, or deactivating and deactivating the catalyst activity. And preferred because of the melt stability and wet heat stability of the polylactic acid film.

Examples of the deactivator used for the catalyst deactivation of the polylactic acid subjected to melt ring-opening polymerization in the presence of the metal-containing catalyst include the following compounds.
That is, from an organic ligand consisting of a group of chelate ligands having an imino group and capable of coordinating to a specific metal-based polymerization catalyst, a phosphorus oxoacid, a phosphorus oxoacid ester, and an organic phosphorus oxoacid compound group represented by the formula (2) It is a resin containing at least one selected and added in an amount of 0.3 to 20 equivalents per equivalent of a metal element of the specific metal-containing catalyst.
_{X 1 -P (= O) m} (OH) n (OX 2) 2-n (2)
(In the formula, m is 0 or 1, n is 1 or 2, and X ₁ and X ₂ each independently represents a hydrocarbon group optionally having a substituent having 1 to 20 carbon atoms.)
The amount of the quenching agent used is more preferably in the range of 0.4 to 15 equivalents, particularly preferably 0.5 to 10 equivalents based on the above criteria.

  Organic ligands (imine compounds), which are phenolic tetradentate chelate ligands having an imino group in the structure and capable of coordinating to metal-based polymerization catalysts, are Bronsted acids like conventional catalyst deactivators. Because it is not a base, it is possible to improve the thermal stability without deteriorating the hydrolysis resistance of the polylactic acid resin composition. Examples of such imine compounds include N, N′-bis (salicylidene) ethylenediamine, N, N′-bis (salicylidene) propanediamine, and the like.

Examples of the phosphorus oxoacid include dihydridooxoline (I) acid, dihydridotetraoxodiphosphorus (II, II) acid, hydridotrioxoline (III) acid, dihydridopentaoxodiphosphoric acid (III), hydridopentaoxodioxy (II, IV) acid, dodecaoxohexaphosphorus (III) acid, hydridooctaoxotriphosphoric acid (III, IV, IV) acid, octaoxotriphosphoric acid (IV, III, IV) acid, hydridohexaoxodiphosphorus (III, V) ) Low oxidation number phosphorus having an acid number of 5 or less, such as acid, hexaoxodiphosphorus (IV) acid, decaoxotetralin (IV) acid, hendecaoxotetralin (IV) acid, eneoxooxo triphosphoric acid (V, IV, IV) acid acid, represented by the general formula _{(xH 2 O · yP 2 O} 5), x / y = 3 of orthophosphoric acid, 2> a x / y> 1, diphosphate than the degree of condensation Polyphosphoric acid called triphosphoric acid, tetraphosphoric acid, pentaphosphoric acid and the like, and mixtures thereof, metaphosphoric acid represented by x / y = 1, especially trimetaphosphoric acid, tetrametaphosphoric acid, 1> x / y> 0 Illustrated are ultraphosphoric acid having a network structure in which a part of the phosphorus pentoxide structure is partly represented, and monovalent and polyhydric alcohols of these acids, partial esters of polyalkylene glycols, and complete ester Is done. From the catalyst deactivation ability, acids or acidic esters are preferably used.

There are no particular restrictions on the alcohol that forms the ester of the phosphorus oxoacid, but the monohydric alcohol is preferably an alcohol represented by the formula (3) which may have a substituent having 1 to 22 carbon atoms. used.
Y-OH (3)
(In the formula, Y represents a hydrocarbon group which may have a substituent having 1 to 22 carbon atoms.)

  Specific examples include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, 2-ethylhexyl alcohol, decanol, dodecanol, benzyl alcohol, cyclohexyl alcohol, hexyl alcohol, phenol, hexadecyl alcohol and the like.

Examples of the polyhydric alcohol include polyhydric alcohols and sugar alcohols represented by the formula (4) which may have a substituent having 2 to 22 carbon atoms.
X (—OH) _a (4)
(In the formula, X represents a hydrocarbon group which may have a substituent having 2 to 22 carbon atoms, and a represents an integer of 2 to 6.)

  Specifically, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, glycerin, pentaerythritol, trimethylolpropane, polyethylene glycol, polypropylene glycol, myo-inositol, D -, L-inositol, inositols such as scyllo-inositol, cyclitol and the like.

  Particularly preferably, phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, phenylphosphonic acid, benzylphosphinic acid, dibutyl phosphate, dinonyl phosphate, N, N′-bis (salicylidene) ) Ethylenediamine and N, N′-bis (salicylidene) propanediamine are exemplified, among which phosphoric acid, phosphorous acid and pyrophosphoric acid are particularly preferable.

These deactivators may be used alone or in combination depending on the case. These deactivators are 0.3 to 20 equivalents, more preferably 0.5 to 15 equivalents, more preferably 0.5 to 10 equivalents, and particularly preferably 0.8 to 1 equivalent per metal element of the specific metal-containing catalyst. 6 to 7 equivalents are used.
If the amount of the deactivator used is too small, the activity of the catalyst metal cannot be sufficiently lowered, and if used excessively, the deactivator may cause decomposition of the resin, which is not preferable.

  The polylactic acid (A) in the present invention is obtained by melt-kneading the polylactic acid (B) component and the polylactic acid (C) component at 220 to 300 ° C. in a weight ratio of 10/90 to 90/10. Can be obtained.

  The weight mixing ratio of the polylactic acid (B) component and the polylactic acid (C) component is preferably 30/70 to 70/30, in order to increase the stereocomplex crystallinity (S) of the polylactic acid (A). A range of 40/60 to 60/40 is preferably selected. A mixing ratio as close to 50/50 as possible is preferably selected.

  The melt kneading temperature ranges from 230 to 300 ° C., preferably from 240 to 280 ° C., more preferably from 245 to 275 ° C., from the viewpoint of improving the stability at the time of melting polylactic acid and the stereocomplex crystallinity (S). Selected.

  By melt-kneading in such a mixing ratio and kneading temperature range, it is preferable that the stereocomplex crystallinity (S) of polylactic acid (A) can be 80% or more. In addition, the stereocomplex crystallinity (S) obtained from the DSC measurement of the polylactic acid film of the present invention is preferably 90% to 100%, more preferably 95% to 100%, and particularly preferably 100%.

  The melt kneading method is not particularly limited, but a conventionally known batch type or continuous type melt mixing apparatus is preferably used. For example, melt stirring tank, single-screw or twin-screw extruder, kneader, non-shaft vertical stirring tank, Sumitomo Heavy Industries Vivolak, Mitsubishi Heavy Industries N-SCR, Hitachi glass blade, lattice blade or Kenix stirrer, or Sulzer SMLX type static mixer equipped pipe type polymerization equipment can be used, but it is a self-cleaning type polymerization equipment in terms of productivity, quality of polylactic acid, especially color tone, non-axial vertical stirring tank, N-SCR, biaxial An extrusion ruder or the like is preferably used.

The polylactic acid (A) of the present invention has a stereocomplex crystallinity (S) determined by DSC measurement of 80% or more, preferably 90% or more, more preferably 95% or more.
Particularly preferred is an embodiment in which the high melting point peak resulting from the stereocomplex polylactic acid determined by DSC measurement is a single peak, that is, an embodiment in which the stereocomplex crystallinity (S) is 100%.

  As described above, the polylactic acid (B) component and the polylactic acid (C) component are melt-kneaded in such a mixing ratio range, and the polylactic acid (A) having such a stereocomplex crystallinity range is melt-extruded to form a film. Flow spots due to two-phase separation can be suppressed, and it is suitable for producing a polylactic acid film having good transparency and excellent heat resistance.

The weight average molecular weight of the polylactic acid (A) in the present invention and the polylactic acid film of the present invention is preferably in the range of 80,000 to 250,000, and more preferably 100,000 to 250,000. Particularly preferred is a range of 120,000 to 200,000.
Such a weight average molecular weight range is suitable for suppressing flow spots and improving transparency, and for enhancing the mechanical properties and durability of the film.

In the present invention, the melting enthalpy of the complex phase crystal determined from the DSC measurement of the polylactic acid film is 35 J / g or more, preferably in the range of 40 J / g to 80 J / g.
The crystal melting enthalpy of 100% polylactic acid crystals is said to be 93 J / g, and it can be said that the polylactic acid film having the above crystallization enthalpy value has a sufficiently high crystallinity and high heat resistance.

The polylactic acid film of the present invention preferably contains at least one of triclinic inorganic particles (D) and phosphate metal salt (E) as a crystallization nucleating agent.
By blending such an agent, the stereocomplex crystallinity (S) of a polylactic acid film or the like can be 90% or more, preferably 95% or more, and more preferably 97% or more.

In particular, it is effective for making the high melting point peak derived from stereocomplex polylactic acid obtained from DSC measurement a single peak, that is, making the stereocomplex crystallinity (S) 100%.
The polylactic acid (A) having such a high stereocomplex crystallinity (S) is suitable for realizing a high stereocomplex crystallinity (S), transparency, and heat resistant film.

  Various agents are known as nucleating agents for improving the crystallinity of polylactic acid. In the present invention, although a clear mechanism of action is unknown, the stereocomplex crystallinity (S) is improved, or Triclinic inorganic particles (D) and / or phosphoric acid ester metal salts (E) suitable for improving the transparency of the polylactic acid film are preferably used.

  Examples of the triclinic inorganic particles (D) include wollastonite, xonotolite, borate, magnesium potassium hydrogen carbonate, calcium metasilicate (α), calcium metasilicate (β) manganese metasilicate. , Calcium sulfate, cerium (III) sulfate, zinc phosphate, zinc dihydrogen phosphate, calcium dihydrogen phosphate, aluminum aluminosilicate, potassium aluminosilicate, and the like.

  Of these, wollastonite, calcium sulfate, and calcium metasilicate are particularly preferred from the viewpoint of improving the stereocomplex crystallinity (S) such as polylactic acid and improving the transparency of the film. And the like are preferable.

  Preferable examples of the phosphoric acid ester metal salt (E) used in the present invention include aromatic organic phosphoric acid ester metal salts represented by the formulas (5) and (6).

One or more types of aromatic organic phosphate metal salts can be used in combination.
In the formula (5), 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 group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, Etc. are exemplified. 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 group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tet-butyl group, and amyl group. , Tet-amyl group, hexyl group, heptyl group, octyl group, iso-octyl group, tet-octyl group, 2-ethylhexyl group, nonyl group, iso-nonyl group, decyl group, iso-decyl group, tet-decyl group , Undecyl group, dodecyl group, tet-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 (5) include those in which R ₁ is a hydrogen atom, and R ₂ and R ₃ are both tet-butyl groups.

In the formula (6), 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 a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, iso-butyl group, tet-butyl group, amyl group, tet-amyl group, hexyl group, heptyl group, octyl group, iso-octyl group, tet-octyl group, 2-ethylhexyl group, nonyl group, iso-nonyl group, A decyl group, an iso-decyl group, a tet-decyl group, an undecyl group, a dodecyl group, a tet-dodecyl group, etc. are 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 ₁ is an alkali metal atom, alkaline earth metal atom or zinc atom, and 1 or 2 when M ₁ is an aluminum atom.

Among the phosphoric acid ester metal salts represented by the formula (6), for example, R ₄ and R ₆ are methyl groups, R ₅ is a tet-butyl group, and M ₁ and M ₂ are aluminum. Can be mentioned.

  Commercially available phosphoric acid ester metal salts, for example, trade name, ADEKA STAB NA-10, ADK STAB NA-11, ADK STAB NA-21, ADK STAB NA-71, ADK STAB NA-30, ADK STAB NA- manufactured by ADEKA Corporation 35 and the like can also be effectively used for the desired purpose as the phosphate metal salt of the present invention.

  Among these, Adeka Stub NA-71 of phosphoric acid ester aluminum salt and Adeka Stub NA-21 containing a phosphoric acid ester aluminum salt and an organic auxiliary are exemplified as preferable materials from the viewpoint of film transparency. Among these, finely dispersed Adeka Stub NA-71 and Adeka Stub NA-21 having an average particle diameter of 5 μm or less, which are pulverized and classified, are preferable.

  The amount of such triclinic inorganic particles (D) and / or phosphate metal salt (E) used is in the range of 0.01 to 5 parts by weight per 100 parts by weight of polylactic acid (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 larger than 5 parts by weight, it may be thermally decomposed during film formation or deteriorated coloration may occur.
Accordingly, a range of 0.05 to 4 parts by weight, preferably 0.1 to 3 parts by weight is selected.

  By using the triclinic inorganic particles (D) and / or the phosphate metal salt (E) in such a quantitative ratio, the formation of flow spots caused by two-phase separation is suppressed when the polylactic acid film of the present invention is formed. It is possible to produce a film having good transparency and good heat resistance.

  Further, the triclinic inorganic particles (D) and / or phosphate metal salts (E) used in the present invention are those having a particle size as small as possible, particularly those having a small content ratio of large particles exceeding 10 μm, Although it is preferable from the viewpoint of the transparency of the polylactic acid film, a film having a thickness of 0.01 to 10 μm is preferably used in practice. More preferably, 0.05 to 7 μm is selected. When the content ratio of large particles exceeding 10 μm exceeds 20%, the haze of the polylactic acid film is increased, which is not preferable.

  Triclinic inorganic particles (D) and / or phosphoric acid ester metal salts (E) having such particle diameters are obtained by commercially available triclinic inorganic particles (D) and / or by a ball mill, sand mill, hammark crusher, or atomizer. It can be obtained by pulverizing the phosphoric ester metal salt (E) and classifying it with various classifiers.

  It is industrially difficult to make the particle diameter of the triclinic inorganic particles (D) and / or the phosphoric acid ester metal salt (E) smaller than 0.01 μm, and it is not necessary to make them so small in practice. However, if the content ratio is larger or larger than 10 μm, the problem that the haze of the film increases is not preferred.

The polylactic acid film of the present invention preferably has a carboxyl group amount of 10 equivalents / 10 ⁶ g or less from the viewpoints of stability during film castability, inhibition of hydrolysis resistance, and inhibition of weight average molecular weight reduction, and 5 equivalents / 10. still more preferably ^{6 g} or less, and particularly preferably 2 or less equivalents / 10 6 ^g.

  In the present invention, depending on the application, as a means of reducing the carboxyl group end group, it is possible to blend a carboxyl group and a reactive carboxyl group-blocking agent, stability during melt film formation and wet heat of the obtained film Preferred for environmental stability.

  Carboxy group capping agent adds terminal carboxyl group of polylactic acid resin to capping and seals carboxyl group of low molecular weight compounds such as lactic acid, lactic acid, formic acid, etc. produced by decomposition reaction of polylactic acid resin and various additives The resin can be stabilized, and there is also an advantage that the resin temperature at the time of film formation can be raised to a temperature that can suppress flow spots.

  As such a carboxyl group-capping agent, it is preferable to use at least one compound selected from a carbodiimide compound, an epoxy compound, an oxazoline compound, an oxazine compound, and an isocyanate compound, and among them, a carbodiimide compound is preferable.

  Examples of the carbodiimide compound used in the present invention include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dioctylcarbodiimide, octyldecylcarbodiimide, di-t-butylcarbodiimide, dibenzylcarbodiimide, diphenylcarbodiimide, N-octadecyl-N′-phenylcarbodiimide. N-benzyl-N′-phenylcarbodiimide, N-benzyl-N′-tolylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, bis (p-nitrophenyl) carbodiimide, bis (p-aminophenyl) Carbodiimide, bis (p-hydroxyphenyl) carbodiimide, bis (p-chlorophenyl) carbodiimide, bis (o-chlorophenol) Nyl) carbodiimide, bis (o-ethylphenyl) carbodiimide, bis (p-ethylphenyl) carbodiimide bis (o-isopropylphenyl) carbodiimide, bis (p-isopropylphenyl) carbodiimide, bis (o-isobutylphenyl) carbodiimide, bis ( p-isobutylphenyl) carbodiimide, bis (2,5-dichlorophenyl) carbodiimide, p-phenylenebis (o-toluylcarbodiimide), p-phenylenebis (cyclohexylcarbodiimide), p-phenylenenebis (p-chlorophenylcarbodiimide), 2 , 6,2 ', 6'-tetraisopropyldiphenylcarbodiimide, hexamethylenebis (cyclohexylcarbodiimide), ethylenebis (phenylcarbodiimide), ethylene Sus (cyclohexylcarbodiimide), bis (2,6-dimethylphenyl) carbodiimide, bis (2,6-diethylphenyl) carbodiimide, bis (2-ethyl-6-isopropylphenyl) carbodiimide, bis (2-butyl-6-isopropyl) Phenyl) carbodiimide, bis (2,6-diisopropylphenyl) carbodiimide, bis (2,6-di-t-butylphenyl) carbodiimide, bis (2,4,6-trimethylphenyl) carbodiimide, bis (2,4,6) -Triisopropylphenyl) carbodiimide, bis (2,4,6-tributylphenyl) carbodiimide, diβ-naphthylcarbosiimide, N-tolyl-N′-cyclohexylcarbosiimide, N-tolyl-N′-phenylcarbosiimide Such as mono or poly Bojiimido compounds.

  Of these, bis (2,6-diisopropylphenyl) carbodiimide and 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide are preferred from the viewpoints of reactivity and stability.

Of these, industrially available dicyclohexylcarbodiimide and diisopropylcarbodiimide are also suitable.
Furthermore, a commercially available polycarbodiimide compound as the polycarbodiimide compound can be suitably used without the need for synthesis.

  As such a commercially available polycarbodiimide compound, for example, Carbodilite LA-1 sold under the trade name of Carbodilite commercially available from Nisshinbo Co., Ltd., or HMV-8CA, with the trade name of Stavaxol from Rhein Chemie Japan Co., Ltd. Examples of commercially available stabuxol I, stabuxol P, stabuxol P100, and the like.

  As an epoxy compound, a glycidyl ether compound, a glycidyl ester compound, a glycidyl amine compound, a glycidyl imide compound, a glycidyl amide compound, and an alicyclic epoxy compound can be preferably used. By blending such an agent, a polylactic acid resin composition and a molded product having excellent mechanical properties, moldability, heat resistance, and durability can be obtained.

  Examples of glycidyl ether compounds include stearyl glycidyl ether, phenyl glycidyl ether, o-phenylphenyl glycidyl ether, ethylene oxide lauryl alcohol glycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetra Bisphenol A diglycidyl obtained by condensation reaction of bisphenols such as methylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and bis (4-hydroxyphenyl) methane with epichlorohydrin Ether type epoxy resin, etc. It can be mentioned. Of these, bisphenol A diglycidyl ether type epoxy resins are preferred.

  Examples of glycidyl ester compounds include benzoic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, stearic acid glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, terephthalic acid diglycidyl ester, phthalic acid diglycidyl ester, and cyclohexanedicarboxylic acid. Examples include diglycidyl ester, adipic acid diglycidyl ester, succinic acid diglycidyl ester, dodecanedioic acid diglycidyl ester, trimellitic acid triglycidyl ester, and pyromellitic acid tetraglycidyl ester. Of these, glycidyl benzoate and glycidyl versatate are preferred.

  Examples of the glycidylamine compound include, for example, tetraglycidylamine diphenylmethane, triglycidyl-p-aminophenol, diglycidylaniline, diglycidyltoluidine, tetraglycidylmetaxylenediamine, triglycidyl isocyanurate, and the like.

  Examples of glycidyl imide and glycidyl amide compounds include, for example, N-glycidyl phthalimide, N-glycidyl-4-methyl phthalimide, N-glycidyl-3-methyl phthalimide, N-glycidyl-4,5-dimethyl phthalimide, N-glycidyl- 3,6-dimethylphthalimide, N-glycidyl-3,4,5,6-tetrabromophthalimide, N-glycidyl-4-n-butyl-5-bromophthalimide, N-glycidylsuccinimide, N-glycidyl-1, 2,3,4-tetrahydrophthalimide, N-glycidylmaleimide, N-glycidyl-α-ethylsuccinimide, N-glycidylbenzamide, N-glycidyl-p-methylbenzamide, N-glycidylnaphthamide, N-glycidylstearylamide etc It is below. Of these, N-glycidylphthalimide is preferable.

  Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexyl-3,4-cyclohexylcarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene diepoxide, N-methyl- 4,5-epoxycyclohexane-1,2-dicarboxylic acid imide, N-phenyl-4,5-epoxycyclohexane-1,2-dicarboxylic acid imide, and the like.

  As other epoxy compounds, epoxy-modified fatty acid glycerides such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized whale oil, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and the like can be used.

  Examples of the oxazoline compound used in the present invention include 2-butoxy-1,3-oxazoline, 2-decyloxy-1,3-oxazoline, 2-stearyloxy-1,3-oxazoline, 2-cyclohexyloxy-1,3. -Oxazoline, 2-allyloxy-1,3-oxazoline, 2-cresyloxy-1,3-oxazoline, 2-o-propylphenoxy-1,3-oxazoline, 2-p-phenylphenoxy-1,3-oxazoline, 2 -Methyl-1,3-oxazoline, 2-heptyl-1,3-oxazoline, 2-oleyl-1,3-oxazoline, 2-cyclohexyl-1,3-oxazoline, 2-methallyl-1,3-oxazoline, 2 -Phenyl-1,3-oxazoline, 2-benzyl-1,3-oxazoline, 2-o-pro Ruphenyl-1,3-oxazoline, 2-m-propylphenyl-1,3-oxazoline, 2-p-phenylphenyl-1,3-oxazoline, 2-p-propylphenyl-1,3-oxazoline, 2,2 '-Bis (1,3-oxazoline), 2,2'-bis (4-methyl-1,3-oxazoline), 2,2'-bis (4-butyl-1,3-oxazoline), 2,2 '-M-phenylenebis (1,3-oxazoline), 2,2'-p-phenylenebis (4-methyl-1,3-oxazoline), 2,2'-ethylenebis (1,3-oxazoline), 2,2′-tetramethylenebis (1,3-oxazoline), 2,2′-hexamethylenebis (1,3-oxazoline), 2,2′-octamethylenebis (1,3-oxazoline), 2, 2'-D Renbis (4-methyl-1,3-oxazoline), 2,2′-tetramethylenebis (4,4′-dimethyl-1,3-oxazoline), 2,2′-cyclohexylenebis (1,3-oxazoline) ), 2,2′-diphenylenebis (4-methyl-1,3-oxazoline) and the like. Furthermore, the polyoxazoline compound etc. which contain the said compound as a monomer unit are mentioned.

  Examples of oxazine compounds used in the present invention include 2-methoxy-5,6-dihydro-4H-1,3-oxazine, 2-propyloxy-5,6-dihydro-4H-1,3-oxazine, 2- Butoxy-5,6-dihydro-4H-1,3-oxazine, 2-hexyloxy-5,6-dihydro-4H-1,3-oxazine, 2-heptyloxy-5,6-dihydro-4H-1, 3-oxazine, 2-nonyloxy-5,6-dihydro-4H-1,3-oxazine, 2-decyloxy-5,6-dihydro-4H-1,3-oxazine, 2-cyclopentyloxy-5,6-dihydro -4H-1,3-oxazine, 2-allyloxy-5,6-dihydro-4H-1,3-oxazine, 2-crotyloxy-5,6-dihydro-4H-1,3-oxa Such as emissions, and the like.

  Further, 2,2′-bis (5,6-dihydro-4H-1,3-oxazine), 2,2′-ethylenebis (5,6-dihydro-4H-1,3-oxazine), 2,2 ′ -Propylene bis (5,6-dihydro-4H-1,3-oxazine), 2,2'-hexamethylene bis (5,6-dihydro-4H-1,3-oxazine), 2,2'-p- Phenylenebis (5,6-dihydro-4H-1,3-oxazine), 2,2′-m-phenylenebis (5,6-dihydro-4H-1,3-oxazine), 2,2′-P, P′-diphenylenebis (5,6-dihydro-4H-1,3-oxazine), and the like. Furthermore, the polyoxazine compound etc. which contain the above-mentioned compound as a monomer unit are mentioned.

  Among the oxazoline compounds and oxazine compounds, 2,2'-m-phenylenebis (1,3-oxazoline) and 2,2'-p-phenylenebis (1,3-oxazoline) are preferably selected.

As an example of the isocyanate compound used in the present invention, for example, aromatic, aliphatic and alicyclic isocyanate compounds and mixtures thereof can be used.
Examples of the monoisocyanate compound include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, and naphthyl isocyanate.

  Specific examples of the diisocyanate include 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2 , 4-tolylene diisocyanate, 2,6-tolylene diisocyanate, (2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate) mixture, hexamethylene diisocyanate, cyclohexane-4,4′-diisocyanate, xylylene diisocyanate , Isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2, - it can be exemplified diisopropylphenyl-1,4-diisocyanate, and the like.

Among these isocyanate compounds, aromatic isocyanates such as 4,4′-diphenylmethane diisocyanate and phenyl isocyanate are preferable.
The said carboxy group sealing agent can select and use 1 type or 2 or more types of compounds suitably.

  The amount of the carboxyl group sealing 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 polylactic acid (A) resin. In the present invention, a sealing reaction catalyst may be further used.

  Examples of such compounds include alkali metal compounds, alkaline earth metal compounds, tertiary amines, imidazole compounds, quaternary ammonium salts, phosphine compounds, phosphonium compounds, phosphate esters, organic acids, Lewis acids, and the like. It is done.

  In order to make the polylactic acid (A) in the present invention contain the above nucleating agent and / or carboxy group blocking agent, the polylactic acid (B) component, the method of containing the polylactic acid (C) component in advance, polylactic acid (B ) Component and polylactic acid (C) component can be blended and contained at the time of melt-kneading, or melt-kneading the polylactic acid (B) component and polylactic acid (C) component to form a casting film.

The polylactic acid (A) composition can be solidified and pelletized once, but can also be melt extruded and formed into a film without solidification.
For blending these agents, various conventionally known methods can be suitably used. For example, polylactic acid and triclinic inorganic particles (D) and / or phosphate metal salt (E) are tumbler, V-type blender, super mixer, nauta mixer, Banbury mixer, kneading roll, uniaxial or biaxial extrusion A method of mixing with a machine or the like is appropriately used.

In the polylactic acid film of the present invention, a lubricant can be applied in the polylactic acid for the purpose of improving film winding and running performance, as long as the object of the present invention is not violated.
This lubricant may be solid or liquid at room temperature, and preferably has a melting point or softening point of 200 ° C. or lower. Specific examples of the lubricant include the following, and two or more of these may be used in combination.

Aliphatic hydrocarbons: liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyethylene wax, polypropylene wax, etc.
Higher fatty acids or metal salts thereof: stearic acid, calcium stearate, hydroxystearic acid, hydrogenated oil, sodium montanate, etc.
Fatty acid amide: stearic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, behenic acid amide, methylene bissteryl amide, etc.
Fatty acid ester: n-butyl stearate, methyl hydroxy stearate, myricyl cellotinate, higher alcohol fatty acid ester, ester wax, etc.
Fatty acid ketone: ketone wax, etc.
Aliphatic higher alcohols: lauryl alcohol, stearyl alcohol, myristyl alcohol, cetyl alcohol, etc.
Polyhydric alcohol fatty acid ester or partial ester: glycerin fatty acid ester, hydroxystearic acid triglyceride, sorbitan fatty acid ester, etc.
Nonionic surfactant: polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene alkylamide, polyoxyethylene fatty acid ester, etc.
Silicone oil: linear methyl silicone oil, methylphenyl silicone oil, modified silicone oil, etc.
Fluorine-based surfactant: fluoroalkyl carboxylic acid, perfluoroalkyl carboxylic acid, monoperfluoroalkyl ethyl phosphate ester, perfluoroalkyl sulfonate, and the like.

  These lubricants may be used alone or in combination of two or more. The lubricant is applied in the range of 0.001 to 1 wt%, more preferably 0.005 to 0.5 wt% in polylactic acid.

In the polylactic acid film of the present invention, a lubricant can be applied in the polylactic acid for the purpose of improving film winding and running performance, as long as the object of the present invention is not violated.
Examples of such lubricants include silica produced by a dry method, silica produced by a wet method, zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, titanium oxide, alumina, zirconia, aluminum hydroxide, Preferable examples include inorganic particles such as calcium oxide, graphite, carbon black, zinc oxide, silicon carbide, and tin oxide; and organic fine particles such as crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles.

As the lubricant, fine particles having an average particle diameter of 0.001 to 5.0 μm are preferable, and one kind can be used, or two or more kinds can be used in combination.
These can be mix | blended in 0.01-0.5 wt% of range with respect to polylactic acid.

  In addition to these agents, an antioxidant, an antistatic agent, a colorant, a pigment, a fluorescent whitening agent, a plasticizer, a cross-linking agent, an ultraviolet absorber and other resins are required as long as they do not contradict the gist of the present invention. Can be added accordingly.

These agents can be appropriately blended at a stage between the start of polylactic acid polymerization and before film formation.
As an addition method, an agent-containing polylactic acid can be produced by using a generally known agent charging method.

  Moreover, in order to add an agent to polylactic acid, conventionally well-known various methods can be used conveniently. For example, a method in which polylactic acid and a phosphoric acid ester metal salt are mixed with a tumbler, V-type blender, super mixer, nauta mixer, Banbury mixer, kneading roll, uniaxial or biaxial extruder or the like is appropriately used.

  The polyclinic acid containing the triclinic inorganic particles (D) and / or the phosphoric acid ester metal salt (E) and the carboxyl group sealing agent thus obtained is once pelletized and then supplied to the film forming apparatus. Is also possible.

  The polylactic acid film of the present invention comprises, as desired, the above-mentioned triclinic inorganic particles (D) and / or phosphate ester metal salt (E), a carboxyl group blocking agent, a sulfonic acid quaternary phosphonium salt, and the above-described lubricant. Is produced by extruding the molten film onto a cooling drum at a temperature of (Tmsc + 20) to (Tmsc + 50) ° C., and then bringing the film into close contact with the rotating cooling drum and cooling.

  At that time, the draft ratio (ratio obtained by dividing the lip opening of the extrusion die by the thickness of the sheet extruded onto the cooling drum) is preferably 2 or more and 80 or less. If the draft ratio is small, the take-off speed of the extrusion die from the lip becomes too slow, and the speed of separation of the polymer from the die lip is slow. From such a viewpoint, the lower limit of the draft ratio is preferably 3 or more, more preferably 5 or more, further preferably 9 or more, and particularly preferably 15 or more. On the other hand, if the draft ratio is too large, the deformation when the polymer leaves the die lip is too large, or the flow becomes unstable and the thickness variation (thickness unevenness) in the longitudinal direction (MD) becomes worse. From such a viewpoint, the upper limit of the draft ratio is preferably 60 or less, more preferably 40 or less, and particularly preferably 30 or less.

  The resin temperature is a temperature at which the resin has sufficient fluidity, that is, a range of (Tmsc + 20) to (Tmsc + 50) (° C.), but it is preferable to melt and extrude at a temperature at which the resin does not decompose. Preferably, a temperature of 240 to 300 ° C., more preferably 245 to 280 ° C., particularly preferably 250 to 275 ° C. is used, in which flow spots are not easily generated. During film casting, it is preferable to produce an unstretched film by cooling and solidifying with a cooling drum while applying an electrostatic charge from an electrode by an electrostatic contact method. At this time, the electrode to which the electrostatic charge is applied is a wire or a knife The shape of a shape is used suitably.

  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, reducing the ability to apply static electricity. It is possible to prevent adhesion of impurities by spraying in the vicinity 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 polylactic acid (A) 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 unstretched film is preferably not substantially stretched, but may be further uniaxially or biaxially stretched as necessary to form a uniaxially stretched film or a biaxially stretched film. In order to obtain such a uniaxially stretched film or a biaxially stretched film, the temperature is such that the unstretched film can be stretched, that is, a glass transition temperature of polylactic acid (hereinafter sometimes referred to as Tg) to (Tg + 80) ° C. or less. Heat and stretch at least uniaxially.

The draw ratio is selected within a range of less than 2 times for a uniaxially stretched film and less than 4 times for an area ratio of a biaxially stretched film.
In biaxial stretching, in addition to simply setting the area ratio within the above range, reducing the difference between the longitudinal and lateral stretching ratios to balance balances the longitudinal and lateral values such as shrinkage and elastic modulus. Is necessary. If the draw ratio does not satisfy the above range, the formability of the polylactic acid film is lowered, which is not preferable.

  The biaxially stretched film is produced 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 a simultaneous axial stretching method in which the longitudinal direction and the transverse direction are simultaneously stretched. can do.

This biaxially stretched film can be further stretched in the longitudinal or lateral uniaxial direction, or in the longitudinal and lateral biaxial directions to form a biaxially restretched film. What is necessary is just to carry out so that it may become the said numerical range.
The uniaxially stretched film or the biaxially stretched film can be reduced in heat shrinkage rate by heat treatment to such an extent that the moldability is not lowered.

  Further heat treatment at a temperature not higher than the high temperature phase melting point Tmsc of the polylactic acid (A) and cooling to room temperature can provide a uniaxially stretched heat-treated film or a biaxially stretched heat-treated film.

  Preferably, the heat treatment temperature is a temperature range from the low-temperature phase melting point Tmh to the high-temperature phase melting point Tmsc (° C.), so that the film is hardly broken and has a sufficient heat setting effect, and has good dimensional stability. It can be a film.

  The unstretched film, uniaxially stretched film, or biaxially stretched film thus obtained can be subjected to surface activation treatment such as plasma treatment, amine treatment, and corona treatment by a conventionally known method if desired.

  Since the polylactic acid film of the present invention has good transparency and good heat resistance, film for packaging, film for condenser (for example, film having a thickness of 3 μm or less), film for printer ribbon (for example, thickness of about 5 μm) Film), heat-sensitive stencil printing film, magnetic recording film (for example, for QIC tape: computer recording film 1/4 inch tape), and Montglare film (for example, film having a thickness of 50 μm or less). In particular, a film having a haze of 4% or less is useful for optical applications. Moreover, since it is excellent in heat resistance and moldability at the same time, even when used in molding applications such as press molding, vacuum molding, pressure molding, in-mold molding, etc., whitening due to heating hardly occurs, which is useful.

  As an optical polylactic acid 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.

Furthermore, since the refractive index of the polylactic acid film of the present invention tends not to change depending on the draw ratio, it is difficult for retardation spots due to stretch spots to occur.
Further, due to 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).

  In addition, when used as a packaging film for foods, the contents are not only visible, but also have high heat resistance, so there are merits such as heat sterilization and heating in a microwave oven. is there.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention does not receive any limitation by this. In addition, each value in an Example was calculated | required according to the following method.

(1) Weight average molecular weight (Mw) and number average molecular weight (Mn):
It calculated | required by the comparison with the polystyrene standard sample by the gel permeation chromatography (GPC).
The GPC measuring instrument has the following configuration, using chloroform eluent, flowing at a column temperature of 40 ° C. and a flow rate of 1.0 ml / min, and injecting 10 μl of a sample having a concentration of 1 mg / ml (chloroform containing 1% hexafluoroisopropanol). And 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 connected in series

(2) Crystal melting point, crystal melting heat (ΔHmh, ΔHmsc) and stereocomplex crystallinity (S):
This was measured by 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 rate of temperature increase of 20 ° C./min in a 1st RUN under a nitrogen atmosphere, and crystal melting temperature (Tmh, Tmsc) and crystal melting heat (ΔHmh, ΔHmsc) Was measured. The stereocomplex crystallinity (S) (unit:%) is about 190 ° C. or lower low-temperature phase crystal melting heat (ΔHmh) and 190 ° C. or higher for polylactic acid composed of poly L-lactic acid component and poly D-lactic acid component. From the high-temperature phase crystal heat of fusion (ΔHmsc), the following formula was used.
[Equation 1]
S = {ΔHmsc / (ΔHmsc + ΔHmh)} × 100 (1)

(3) 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 (A) resin 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 judged that the melt stability passed.
The reduced viscosity (ηsp / c) was measured by dissolving 1.2 mg of a sample in 100 ml of [tetrachloroethane / phenol = (6/4) wt mixed solvent] at 35 ° C. using an Ubbelohde viscosity tube.

(4) Wet heat stability (%):
The sample was held at 80 ° C. and 90% RH for 11 hours, and the retention rate (%) of the reduced viscosity (ηsp / 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.

(5) Haze measurement:
The measurement was performed according to 6.4 of JIS K7105-1981 using Nippon Denshoku Co., Ltd. Hazemeter MDH2000.
When the haze exceeded 10%, it was judged that the transparency was poor. When the haze was 1% or less, it was judged that the transparency was usable for an optical film.
Further, the sample was heat-treated at 140 ° C. for 10 minutes using a hot air dryer, the haze was measured by the same method as described above, and the difference in haze before and after the heat treatment (haze after heat treatment−haze before heat treatment) was determined. The change.

(6) Optical purity Optical purity is determined by placing a dilute solution of polylactic acid dissolved in chloroform into a predetermined container and measuring the degree of flash using a flash intensity measuring device. In the case of D-lactic acid, the optical purity was defined as the percentage calculated from the optical rotation of the sample by the proportional formula with -100%.

(7) Thickness variation The thickness of the sample was measured 2 m in the longitudinal direction (MD) using an electronic micrometer, and the ratio (percentage) obtained by dividing the difference between the maximum thickness and the minimum thickness by the average thickness was determined. (Unit:%) and evaluated according to the following.
◎: 2% or less ○: More than 2% and less than 5% △: More than 5% and less than 10% ×: More than 10% If the thickness variation is large, the orientation of the surface layer at the time of film formation is fluctuating. Haze fluctuations tend to increase, which is not preferable. Moreover, the workability at the time of molding tends to deteriorate, which is not preferable. Specifically, when the thickness spot exceeds 10%, it cannot be put into practical use.

[Reference Example 1] Synthesis example of polylactic acid by melt ring-opening polymerization of lactide Vertical stirring tank equipped with full zone blades equipped with vacuum pipe, nitrogen gas pipe, catalyst, L-lactide solution addition pipe, alcohol initiator addition pipe ( 40L) was replaced with nitrogen, and 30 kg of L-lactide, 0.90 kg of stearyl alcohol (0.030 mol / kg) and 6.14 g of tin octylate (5.05 × 10 ⁻⁴ mol / 1 kg) were charged, and the nitrogen pressure was 106. The temperature was raised to 150 ° C. in an atmosphere of 4 kPa. When the contents were dissolved, stirring was started and the internal temperature was further raised to 190 ° C. Since the reaction started when the internal temperature exceeded 180 ° C., cooling was started, and the internal temperature was maintained from 185 ° C. to 190 ° C., and the reaction was continued for 1 hour. Further, with stirring, the reaction was carried out for 1 hour at a nitrogen pressure of 106.4 kPa and an internal temperature of 200 ° C. to 210 ° C. Then, stirring was stopped and a phosphorus-based catalyst deactivator was added.

Further, after leaving for 20 minutes to remove bubbles, the internal pressure was increased from 2 to 3 atm with nitrogen pressure, and the prepolymer was extruded into a chip cutter to pelletize a prepolymer having a weight average molecular weight of 130,000 and a molecular weight dispersion of 1.8. .
Further, the pellets are dissolved by an extruder, charged into a non-axial vertical reactor at 15 kg / hr, depressurized to 10.13 kPa to reduce the remaining lactide, and the poly L-lactic acid resin after chipping it again is The weight average molecular weight was 120,000, the molecular weight dispersion was 1.8, and the lactide content was 0.005 wt%.
A similar synthetic experiment was conducted using D-lactide instead of L-lactide, and a poly-D-lactic acid resin having a weight average molecular weight of 120,000, a molecular weight dispersion of 1.8, and a lactide content of 0.005 wt% was polymerized. .

[Examples 1-2, 4-7, Comparative Example 1]
The poly L-lactic acid resin and poly D-lactic acid resin produced in the synthesis example described above were each dried at 120 ° C. for 5 hours to obtain a mixture having a weight ratio of 1/1. After mixing 100 parts by weight of the obtained mixture with a crystallization nucleating agent (triclinic inorganic particles (D) and / or phosphoric acid ester metal salt (E)) in the amount shown in the table, the mixture was heated at 2 at the temperature shown in the table. Melting and kneading with a shaft extruder, using a die having a lip opening described in the table, melt extrusion at a die temperature of 260 ° C. at a casting speed of 40 m / min, using a platinum coated linear electrode, It was adhered and solidified on the surface of the mirror-cooled drum by an electrostatic casting method.
In all experiments, the melt stability was 80% or more and passed. The results are listed in Table 1.

[Example 3]
In Example 2, in addition to the crystallization nucleating agent, 0.3 part by weight of Carbodilite LA-1 (Nisshinbo Co., Ltd.) was mixed as a carboxyl group blocking agent.

  The polylactic acid film of the present invention is a film having good transparency and heat resistance, and is suitable for a capacitor film, a printer film, and a ceramic liner film. Moreover, taking advantage of good transparency, it is also suitable for optical applications. Moreover, taking advantage of the good moldability and moldability at the same time, it is also suitable for molding applications.

Claims (12)

A polylactic acid (B) component containing 0 to 10 mol% of a component other than the L-lactic acid unit as a main component, and a component other than the L-lactic acid unit as a main component and a component other than the D-lactic acid unit as 0 A polylactic acid film obtained by melt-extruding polylactic acid (A) obtained by melt-kneading a polylactic acid (C) component containing 10 mol% to 10 mol% in a weight ratio of (B / C) = 10/90 to 90/10 The change in haze after heat treatment at 140 ° C. for 10 minutes with a differential scanning calorimeter measurement (DSC measurement) and a stereocomplex crystallinity (S) of 90% or more, 10% or less, and the following formula: Polylactic acid film having 5% or less.
[Equation 1]
S = {ΔHmsc / (ΔHmsc + ΔHmh)} × 100 (1)
(In the formula, ΔHmh is the melting enthalpy of the low melting point melting peak temperature determined from DSC measurement of less than 190 ° C., and ΔHmsc is the high melting point of the crystal melting peak temperature calculated from DSC measurement of 190 ° C. or higher. Represents the melting enthalpy of the melting peak.)   The polylactic acid film according to claim 1, wherein the polylactic acid film is stretched in a uniaxial direction to less than 2 times.   The polylactic acid film according to claim 1, wherein the polylactic acid film is stretched to an area magnification of less than 4 times.   The polylactic acid film according to any one of claims 1 to 3, comprising triclinic inorganic particles (D) and / or a phosphate metal salt (E).   The polylactic acid film according to any one of claims 1 to 4, wherein the carboxyl end group concentration is 0 to 10 eq / ton.   The polylactic acid film according to any one of claims 1 to 5, wherein the polylactic acid (A) has a weight average molecular weight of 80,000 to 250,000. A polylactic acid (B) component containing 0 to 10 mol% of a component other than the L-lactic acid unit as a main component and a component other than the L-lactic acid unit, and a component other than the D-lactic acid unit as a main component having a D-lactic acid unit as 0 to 0 A polylactic acid (A) obtained by melt-kneading a polylactic acid (C) component containing 10 mol% with a weight ratio of (B / C) = 10/90 to 90/10 is a resin of polylactic acid (A). A method for producing a polylactic acid film, characterized in that melt extrusion is performed in a temperature range of (Tmsc + 20) to (Tmsc + 50) (° C.).
(Here, Tmsc represents the peak temperature of the high melting point crystal melting peak having a peak temperature of 190 ° C. or higher obtained from the DSC measurement.)   The manufacturing method according to claim 7, wherein the draft ratio is 2 or more and 80 or less.   9. The production method according to claim 7, wherein after the melt extrusion, the production method is substantially not stretched, uniaxially stretched to less than 2 times, or biaxially stretched to less than 4 times in terms of surface magnification.   The optical polylactic acid film according to any one of claims 1 to 6.   The polylactic acid film for packaging according to any one of claims 1 to 6.   The molding polylactic acid film according to claim 1.