JPWO2014208403A1 - Method for producing polylactic acid resin film - Google Patents

Abstract

It is an object of the present invention to provide a polylactic acid-based resin plasticized film which is molded by an inflation molding method and does not tighten and a method for producing the same. A method for producing a polylactic acid resin plasticized film by molding a polylactic acid resin composition containing 10 to 30 parts by weight of a plasticizer with respect to 100 parts by weight of polylactic acid by an inflation molding method. Provided is a method for producing a polylactic acid-based resin plasticized film, comprising a step of heat-treating in a step after discharge.

Description

  The present invention relates to a method for producing a plasticized film of a polylactic acid resin softened with a plasticizer. More specifically, the present invention relates to a method for producing a plasticized film of a polylactic acid-based resin that does not deform during storage at room temperature after being formed by inflation molding.

  In recent years, with increasing environmental awareness, attention has been focused on soil pollution problems caused by the disposal of plastic products and global warming problems caused by increased carbon dioxide caused by incineration. As a measure against the former, various biodegradable resins, and as a measure against the latter, a resin made of biomass (plant-derived raw material) that does not give a new carbon dioxide load to the atmosphere even if it is incinerated has been extensively researched and developed. ing.

  In particular, polylactic acid has been extensively researched and developed as a resin for solving such problems. Polylactic acid is 100% biodegradable within a few months to one year in the animal body, and begins to degrade in weeks in a moist environment such as soil and seawater, and disappears in about one to several years. . In addition, the decomposition product has characteristics that it is lactic acid, carbon dioxide, and water that are harmless to the human body.

  In recent years, polylactic acid has been produced in a large amount and at low cost by the fermentation method of L-lactic acid as a raw material, and has a high decomposition rate in compost, resistance to mold, and odor resistance to foods. It has been expected to expand its application field by having excellent characteristics such as color resistance.

  However, since polylactic acid has high rigidity, it is difficult to say that it is an appropriate resin for soft film applications that require flexibility, such as agricultural multi-films, food packaging bags, and garbage bags.

In general, methods for softening a resin include methods such as blending soft polymers and adding a plasticizer.
However, in the method of blending soft polymers, considering the biodegradability, the resin to be blended is limited to a biodegradable resin having flexibility. Examples of such a resin include polybutylene succinate, polyethylene succinate, polycaprolactone, and the like. However, in this method, it is necessary to add a large amount of a soft polymer in order to impart sufficient flexibility (for example, an elastic modulus of 1000 MPa or less) to polylactic acid. For example, polybutylene succinate needs to be added in an amount of 60% by weight or more of the whole, and as a result, the above-described features of polylactic acid are impaired. In addition, it has little elongation when pulled and is not very practical as a flexible film.

  On the other hand, a film softened by adding a plasticizer is generally referred to as a plasticized film, but the method of adding the plasticizer does not melt the resin composition even if sufficient flexibility can be imparted to the resin composition. As a result, the film forming method is limited, for example, the viscosity is lowered and the inflation molding cannot be performed. In addition, the method of adding a plasticizer has a problem that the plasticizer bleeds out. Therefore, in order to put this method into practical use, several problems must be solved.

  Examples of the method for forming the plasticized film include inflation molding, T-die film extrusion molding, and extrusion lamination molding. In particular, the inflation molding method can be performed with a compact apparatus, is superior in productivity for a small variety of products, and is low in cost as compared with other molding methods. Moreover, since the film shape obtained is cylindrical (seamless), it is suitable for manufacturing food packaging bags and bags.

  A method for forming a polylactic acid-based resin into a film by inflation molding is disclosed in, for example, Patent Documents 1 to 3 (WO 1999/45067, JP 3510218, and JP 11-116788). However, the methods described in these documents use an alloy of polylactic acid and other aliphatic esters, and are not formed into a film of a resin of polylactic acid alone, so that there is a problem that the characteristics of polylactic acid are impaired. .

  Therefore, in Patent Document 4 (Japanese Patent Application Laid-Open No. 2008-260895), there is a method of using a polylactic acid softened with a plasticizer and producing a plasticized film having both practical strength and flexibility by inflation molding. It is disclosed. However, even in the method described in this document, there is a problem that the core deforms when stored at around room temperature after molding and the core cannot be removed from the wound roll.

WO 1999/45067 Japanese Patent No. 3510218 JP-A-11-116788 JP 2008-260895 A

  An object of the present invention is to provide a polylactic acid-based resin plasticized film which is molded by an inflation molding method and does not tighten (a state where the core is difficult to come off from the roll) and a method for producing the same. More specifically, a plasticized film of a polylactic acid-based resin softened with a plasticizer is molded with an inflation molding machine and stored in a roll shape near room temperature, so that the core does not come off efficiently. The object is to provide a method for forming a polylactic acid-based resin plasticized film that can be produced.

  As a result of intensive studies to solve the above problems, the present inventors have found that the phenomenon of tightening is caused by the stress generated at the rising part of inflation molding (the part in which the resin is inflated with air after discharge of the die). Since it remained even after winding, it was found that the film was deformed over time during storage. Furthermore, the present inventors have found that by performing a heat treatment before film storage (during film formation or after film formation), deformation during film storage can be suppressed, and the present invention has been completed.

Thus, according to the present invention, the following method is provided.
(Item 1) A method for producing a polylactic acid-based resin plasticized film by molding a polylactic acid-based resin composition containing 10 to 30 parts by weight of a plasticizer with respect to 100 parts by weight of polylactic acid by an inflation molding method. A method for producing a polylactic acid-based resin plasticized film comprising a step of heat treatment in a step after discharging a die for inflation molding.
(Item 2) The method according to item 1, wherein the plasticizer is benzyl alkyl diglycol adipate.
(Item 3) The method according to Item 1 or 2, wherein the heat treatment is a method in which the formed film is brought into contact with a medium having a temperature higher than 40 ° C and not higher than 100 ° C for 2 to 300 seconds.
(Item 4) The manufacturing method according to Item 1 or 2, wherein the heat treatment is a method in which a molded film is brought into contact with a heating surface that is higher than 40 ° C and 100 ° C or lower for 2 to 300 seconds.
(Item 5) The manufacturing method according to any one of Items 1 to 4, wherein the heat treatment is performed during a process from discharge of a die for inflation molding to first winding of the plasticized film.
(Item 6) The manufacturing method according to any one of Items 1 to 5, wherein the heat treatment is performed after the plasticized film is wound up once after inflation molding.
(Item 7) The manufacturing method according to any one of Items 1 to 6, wherein the plasticized film is a plasticized film that does not wind even if maintained in a roll shape at 20 to 40 ° C. .
(Item 8) Any one of Items 1 to 7, wherein the plasticized film is a plasticized film that does not generate wrinkles and / or blocking even when maintained in a roll shape at 20 to 40 ° C. The manufacturing method as described in one.
(Item 9) A method for producing a polylactic acid-based resin plasticized film by an inflation molding method, comprising a step of heat treatment in a step after discharge of a die for inflation molding, A method for preventing winding tightening, wrinkle generation and / or blocking.
(Item 10) A polylactic acid-based resin plasticized film molded by an inflation molding method, wherein the film is not tightened.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which shape | molds the polylactic acid-type resin plasticized film which is not tightened by an inflation molding method, and the polylactic acid-type resin plasticized film which is not wound can be provided. More specifically, after a plasticized film of a polylactic acid-based resin softened with a plasticizer is produced by an inflation molding method, the core remains even when stored in the roll state at around room temperature (about 20 to about 40 ° C.). There is no possibility that it will not come off (occurrence of tightening), and work can be done efficiently on site. Furthermore, according to the present invention, even when the plasticized film is stored in a roll state at about 20 ° C. to about 40 ° C., it is possible to prevent wrinkling and blocking of the plasticized film, thereby reducing product quality. Can be prevented.

It is a schematic diagram of an inflation molding process. It is the schematic diagram which showed the flow to an inflation shaping | molding process and the storage of a film. It is a schematic diagram of the heat roll used by the heat processing in Examples 13-23 and Comparative Example 7.

  Details of the present invention will be described below.

  In the present invention, “winding tightening” refers to a state in which it is difficult to remove the core around which the film is wound from the roll when the formed film is wound around the core into a roll shape and the roll state is maintained. Include. For example, a state in which the roll core is difficult to separate from the roll-shaped film due to the film shrinking and tightly wound by the core is also included in the “winding tightening”.

<the film>
(Plasticized film)
First, the plasticized film of the present invention will be described.

  In a preferred embodiment of the present invention, the plasticized film is a film obtained by inflation molding a polylactic acid resin composition obtained by softening polylactic acid with a plasticizer. The tensile modulus of the plasticized film is preferably about 100 to 1500 MPa, more preferably about 100 to 1000 MPa, and still more preferably about 110 to 800 MPa from a practical aspect. In addition, the elongation at break of the plasticized film is preferably about 20 to 400%, more preferably about 100 to 375%, and still more preferably about 150 to 350% from the practical aspect. If the tensile elastic modulus is in the above range, the film has sufficient flexibility, and if it is in the above elongation range at break, the film has a practically sufficient degree of freedom, and is practical in shape stability. Is obtained. Although the thickness of a film changes with uses, it can be normally set to about 5-500 micrometers.

(Tensile modulus)
The tensile elastic modulus of the film is a value measured by pulling at a pulling speed of 200 mm / min using a universal testing machine (Autograph; AG-1 manufactured by SIMADZU) based on JIS standard (JIS K7127).

(Elongation at break)
The elongation at break of the film is a value measured by pulling at a pulling speed of 200 mm / min using a universal testing machine (autograph; AG-1 manufactured by SIMADZU) based on JIS standard (JIS K7127). .

<Polylactic acid resin composition>
Next, the polylactic acid resin composition will be described.

(Polylactic acid)
For the polylactic acid used in the present invention, the raw material monomer is not particularly limited, and examples thereof include known monomers such as L-lactic acid, D-lactic acid, DL-lactic acid, mixtures thereof, and lactide which is a cyclic dimer of lactic acid. be able to. The polylactic acid may be one obtained by polymerizing a single monomer, or may be one obtained by polymerizing a plurality of types of monomers, and may be appropriately selected in order to obtain the desired plasticized film. . Lactic acid is a useful raw material among biodegradable aliphatic polyester resins in that it can be obtained by fermenting renewable resources such as sugar and starch.

  In one embodiment of the present invention, the weight average molecular weight of the polylactic acid is not particularly limited, but is preferably about 10,000 to 1,000,000 from the viewpoint of processability and / or physical properties of the film after molding, etc. About 10,000 is more preferable, and about 50,000 to 400,000 is more preferable. Polylactic acid having a weight average molecular weight in the above range is preferably used because it has sufficient mechanical strength and excellent workability. In the present invention, the weight average molecular weight is a value measured by gel permeation chromatography. Specifically, the gel permeation chromatography uses HLC-8120GPC manufactured by Tosoh Corporation, the column uses TSKgel G4000Hxl × 1 of the company, and the analysis uses GPC-8020 model II of the company, and the flow rate is 1 ml / min. Measurement is performed using polystyrene having a known molecular weight as a standard sample.

(Plasticizer)
The plasticizer used in the present invention is not particularly limited as long as it is a plasticizer for polylactic acid. Various plasticizers usually used in this field (for example, citric acid ester, fatty acid ester of glycerin, fatty acid ester of glycol, Alternatively, an aliphatic dibasic acid ester or the like may be used. The plasticizer is preferably an aliphatic dibasic acid ester, for example, from the viewpoint of setting the melt viscosity of the polylactic acid resin composition to an appropriate value, and an adipate ester plasticizer containing benzylalkyldiglycol adipate is used. Is particularly preferred. The alkyl group of the benzylalkyldiglycol adipate may be either linear or branched, but is preferably linear. Moreover, 1-20 are preferable, as for carbon number of an alkyl group, 1-8 are more preferable, and 1-4 are still more preferable. Particularly preferred are benzyl methyl diglycol adipate, benzyl ethyl diglycol adipate, benzyl n-propyl diglycol adipate, and benzyl n-butyl diglycol adipate having a linear alkyl group having 1 to 4 carbon atoms.

  In one embodiment of the present invention, the content of the plasticizer is preferably about 10 to 30 parts by weight, more preferably about 12 to 28 parts by weight, and more preferably about 15 to 26 parts by weight with respect to 100 parts by weight of the polylactic acid resin. Even more preferred. If it is the said range, the film which has a practically sufficient softness | flexibility will be obtained, and the resin composition of the intensity | strength suitable for inflation molding will be obtained.

(Hydrolysis inhibitor)
The polylactic acid resin composition of the present invention is not essential, but may further contain a hydrolysis inhibitor.
As the hydrolysis inhibitor, a compound known as a hydrolysis inhibitor for polyester resins can be used without limitation. Examples of such hydrolysis inhibitors include carbodiimide compounds, oxozoline compounds, and isocyanate compounds. Of these, carbodiimide compounds are preferred.

  The carbodiimide compound preferably exhibits an effect of suppressing hydrolysis of the polylactic acid resin by crosslinking reaction with the terminal carboxylic acid of the polylactic acid resin. The carbodiimide compound is not particularly limited as long as it has one or more carbodiimide groups in the molecule. For example, a carbodiimide compound synthesized by a decarboxylation reaction from an isocyanate compound according to a conventionally known method can be used. Moreover, you may use what is marketed.

In one embodiment of the present invention, the carbodiimide compound has a basic structure represented by the following general formula (1).
-(N = C = N-R-) _n- (1)
(In the above formula (1), n represents an integer of 1 or more. Also, R represents an aliphatic group that may have a substituent (for example, a linear or branched alkane, alkene, alkyne, etc.), Alicyclic (eg, monocyclic, bicyclic or polycyclic cycloalkane, spiro ring, etc.) or aromatic (eg, monocyclic or polycyclic benzene aromatic, furan, thiophene, pyrrole, imidazole, etc. (Organic bond unit such as aromatic)

  More specifically, the monocarbodiimide compound having one carbodiimide group in the molecule (the compound in which n is 1 in the above formula (1)) is an aliphatic or alicyclic ring such as diisopropylcarbodiimide, dicyclohexylcarbodiimide, dioctylcarbodiimide and the like. Examples thereof include aromatic monocarbodiimides such as aromatic monocarbodiimides and diphenylcarbodiimides.

  Furthermore, as an isocyanate compound (a compound in which n is 2 or more in the above formula (1)) in the synthesis of a polycarbodiimide having two or more carbodiimide groups in the molecule, 1,3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane Aromatic diisocyanates such as diisocyanates; 1,4-cyclohexane diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, isophorone diisocyanate , 4,4'-dicyclohexylmethane Soshianato, aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, and the like. Polycarbodiimide may have all or part of the isocyanate group remaining at the end sealed, and as such a sealing agent, monoisocyanate such as cyclohexyl isocyanate, phenyl isocyanate, tolyl isocyanate, etc. Compound: Compounds having active hydrogen such as hydroxyl group and amino group are exemplified.

Among the carbodiimide compounds, polycarbodiimide having two or more carbodiimide groups in the molecule is preferable from the viewpoint of improving hydrolysis resistance of a molded product molded from the obtained resin composition. From the viewpoint of the compatibility of the above and the hydrolysis resistance of the molded product molded from the resulting resin composition, an aliphatic or alicyclic carbodiimide, a polycarbodiimide obtained from an aliphatic or alicyclic diisocyanate is preferable. . Specific examples of such a polycarbodiimide compound include Carbodilite LA-1 and HMV-15CA manufactured by Nisshinbo Industries, Ltd.
The hydrolysis inhibitor can be used alone or in combination of two or more.

  In one embodiment of the present invention, the content of the hydrolysis inhibitor is preferably about 0.1 to 5 parts by weight, more preferably about 0.5 to 3 parts by weight, with respect to 100 parts by weight of the polylactic acid resin. About 1-2 parts by weight is even more preferable. When the addition amount of the hydrolysis inhibitor is within the above range, a decrease in viscosity due to a decrease in molecular weight is prevented, and inflation molding can be performed smoothly. Further, an increase in viscosity due to an excessive crosslinking reaction is prevented, and inflation molding can be performed smoothly.

(Other additives)
If necessary, other components usually added to the biodegradable resin composition can be added to the polylactic acid resin composition of the present invention as long as the effects of the present invention are not impaired. Examples of such components include crystal nucleating agents, modifiers, fragrances, antibacterial agents, pigments, dyes, heat-resistant agents, antioxidants, weathering agents, lubricants, antistatic agents, stabilizers, fillers, and reinforcing agents. , Antiblocking agents, flame retardants, wood flour, starch and the like.

<Method for producing plasticized film>
Next, the method for producing the plasticized film of the present invention will be specifically described.

(Kneading)
After mixing the above components in a desired ratio, the mixture may be kneaded at a temperature of about 130 to 250 ° C., preferably about 140 to 200 ° C., using a twin screw extruder to produce a molding material. In the case of a small twin screw extruder, the discharge amount in the twin screw extruder may be about 1 to 20 kg / hour, preferably about 2 to 10 kg / hour.

(Molding)
The molding material prepared by the above method is suitable for molding into a film by an inflation molding method. In a preferred embodiment of the present invention, the molding material is formed into a film by an inflation molding method. The inflation molding method is suitable for manufacturing a small variety of products, and has an advantage that the film can be easily formed into a bag shape because it is obtained in a cylindrical shape.

  The inflation molding method may be performed according to a known method, a method known per se, or a method analogous thereto. Specifically, as an inflation molding method, a molding material added from a hopper is usually melted in an extruder, and the melted product is used as a die for inflation molding such as a ring die, a circular die, or a round die. 1 was extruded from the base (1 in FIG. 1), expanded by air flow (2 in FIG. 1), then flattened with a guide plate (3 in FIG. 1) arranged in a palm shape, and rolled. By winding up (5 of FIG. 1), a cylindrical molded body (film) can be manufactured. The temperature of the polylactic acid resin composition at the time of inflation molding is not particularly limited as long as it is a temperature at which the polylactic acid resin composition melts. However, it is usually about 140 to 200 ° C, and more preferably about 150 to 180 ° C.

(Expansion ratio)
The expansion ratio of the inflation molding of the present invention may be a ratio generally used in film molding, preferably 1.2 to 5, more preferably 1.5 to 4, and 1.8. It is especially preferable that it is ~ 3. The expansion ratio can be controlled by adjusting the temperature of the resin discharge part of the molding machine and the air blowing amount.
The expansion ratio is obtained by the following formula.
Expansion ratio (BUR) = Wound film width / Die diameter

(Heat treatment)
In a preferred embodiment of the present invention, the method for producing a plasticized film includes a step of heat-treating the plasticized film in a step after discharging a die for inflation molding (1 in FIG. 1).

  The heat treatment may be performed either during or after inflation molding, or both. Inflation molding refers to the period from the discharge of the die of the molding machine to the first winding of the film (2 to 5 in FIG. 1). The term “after inflation molding” refers to the period from when the film is first wound up to when it is moved to a storage location. Specifically, during the period from when the film is drawn out from the first roll taken up to the second roll (7 in FIG. 2), or the first roll-like film is taken out as it is to the storage location. It means the time until it is carried (the arrow directly connecting 5 and 9 in FIG. 2).

The heat treatment method is not particularly limited as long as the film can be sufficiently heat treated. Specifically, for example, it may be performed by bringing a film and a medium in a specific temperature range or a heating surface into contact with each other for a specific time. The temperature of the medium or the heating surface is preferably higher than 40 ° C. and not higher than 100 ° C. from the viewpoint of preventing the tightening of the plasticized film during storage and the viewpoint of production efficiency, and is preferably 50 to 90 ° C. Is more preferable, and 60 to 85 ° C. is particularly preferable. The time for bringing the film into contact with the medium or the heating surface is preferably 2 to 300 seconds, more preferably 5 to 120 seconds, and more preferably 10 seconds from the viewpoint of preventing the tightening of the plasticized film during storage and the viewpoint of production efficiency. -90 seconds are particularly preferred. The number of times the film is brought into contact with the medium or the heating surface is not particularly limited. One time may be sufficient and multiple times may be sufficient. In the case of multiple times, the total contact time may be within the above time range.
Within this range, the residual stress immediately after film formation can be sufficiently reduced, and the film being stored will not be deformed near room temperature.

  The heating means for the medium or the heating surface is not particularly limited as long as it is a commonly used means such as steam, electricity, dielectric heat generation, infrared rays or the like. What is necessary is just to select suitably considering the scale and safety | security of an apparatus.

(Medium)
The medium used in the heat treatment of the present invention is not particularly limited as long as the film can be sufficiently heated, and various media may be used. Specifically, air, an inert gas (nitrogen, helium, neon, argon, etc.), water, etc. are mentioned, for example. Air and / or water are preferred from the viewpoint of heating efficiency and cost.

(Heating surface)
The heating surface used in the heat treatment of the present invention is an object having a certain area that is maintained in a specific temperature range. The heating surface may be either a flat surface or a curved surface. The fixed area is not particularly limited as long as the film can be sufficiently heated. Further, from the viewpoint of heating efficiency, it is preferable that the heating surface has a smooth surface in contact with the film.
The material of the heating surface is not particularly limited as long as the film can be sufficiently heated, and various materials may be used. Specific examples include metals such as iron, copper, titanium, and nickel, alloys such as stainless steel and carbon steel, ceramics, resins, rubbers, and glass. From the viewpoint of heating efficiency and cost, copper or carbon steel is preferred.

  In one embodiment of the present invention, the heating surface is not particularly limited. Specifically, for example, a metal plate (including an alloy plate), a ceramic plate, a resin plate, a metal roll (including an alloy roll), a ceramic roll, A resin roll, a rubber roll, etc. are mentioned.

  In another embodiment of the present invention, a metal roll is used as the heating surface. The material for the metal roll is not particularly limited as long as it is generally used, and examples thereof include copper, carbon steel, stainless steel, titanium, nickel produced by electroforming, and the like. The surface of the metal roll may be subjected to a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

  In addition, the process which cools the said plasticization film after the said heat processing in this invention does not need to exist. In one embodiment of the present invention, the temperature of the plasticized film in 5 of FIG. 2 or 8 of FIG. 2 is about 50 ° C. or less, preferably about 40 ° C. or less, more preferably about 30 from the viewpoint of maintaining the quality of the film. It should just be below ℃.

  A particularly preferred embodiment of the present invention is a method for producing a polylactic acid resin plasticized film by molding a polylactic acid resin composition containing 100 parts by weight of polylactic acid and 10 to 30 parts by weight of a plasticizer by an inflation molding method. The present invention also relates to a method for producing a polylactic acid resin plasticized film, wherein a heat treatment step is included in a step after discharging a die for inflation molding. The polylactic acid, the plasticizer, and the heat treatment method may be as described above. In this embodiment, the heat treatment is included in the production method, so that even if the obtained polylactic acid resin plasticized film is maintained in a roll state at about 20 to about 40 ° C., the plasticized film is tightly wound and wrinkled. Occurrence, blocking, etc. are suppressed. Although the period maintained in a roll state is not particularly limited, it may be, for example, usually one month or more, half a year or more from the viewpoint of quality maintenance, more preferably one year or more.

  In another preferred embodiment of the present invention, when the polylactic acid-based resin plasticized film molded by the inflation molding method is stored in a roll form at about 20 ° C. to about 40 ° C., the plastic film is tightened. The present invention relates to a method for preventing generation of wrinkles and / or blocking. Specifically, the plasticized film is heat-treated before storage. The method for carrying out the polylactic acid resin plasticized film and the heat treatment may be the same as described above.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated in more detail, this invention is not limited to these.

(1) Material polylactic acid: Ingeo Biopolymer 4043D
(Manufactured by NatureWorks LLC; L-form 95.75 wt%: D-form 4.25 wt%)
Plasticizer: DAIFACTY-101
(Daihachi Chemical Industry Co., Ltd .; benzyl alkyl diglycol adipate-containing adipic acid ester composition)
Crystal nucleating agent: Eco Promote (Nissan Chemical Industries, Ltd .; zinc phenylphosphonate)
Hydrolysis inhibitor: Carbodilite HMV-15CA (Nisshinbo Chemical Co., Ltd.)

(2) Evaluating Method for Easily Pulling Out Film (Presence of Tightening) The film was wound up by 50 m on a paper-made paper core having an outer diameter of 8 cm and a length of 34 cm, and a roll of film was prepared. After storing the roll at 30 to 35 ° C. for 24 hours without removing the roll, the ease with which the paper core was removed from the roll was evaluated according to the following criteria.
○ The core was easily removed from the roll in the wound shape. × The core could not be removed without breaking the roll shape.

(3) Kneading of resin composition Each component was mixed with polylactic acid at the ratio shown in Table 1 below, and the kneading temperature was set to 150 ° C using a twin screw extruder (TEM-37BS manufactured by Toshiba Machine Co., Ltd.). And kneading to obtain a molding material.

(4) Molding of film (Example 1)
The molding material A was melted with an inflation molding machine (YEI-S45-60-R, manufactured by Yoshii Iron Works Co., Ltd.) at a cylinder set temperature of 160 ° C., and crushed at a expansion ratio (BUR) of 2 with a thickness of 50 μm. A cylindrical film having a time width of 30 cm was formed, and a film that was passed through 80 ° C. warm water for 60 seconds at 4d in FIG. 2 as a heat treatment was evaluated by the above evaluation method. The results are shown in Table 2.
(Comparative Example 1)
The same operation and evaluation as in Example 1 were performed except that the heat treatment was not performed. The results are shown in Table 2.
(Example 2)
The same operation and evaluation as in Example 1 were performed except that the molding material A was changed to B. The results are shown in Table 2.
(Comparative Example 2)
The same operation and evaluation as in Example 2 were performed except that the heat treatment was not performed. The results are shown in Table 2.
(Example 3)
Except that the molding material A was changed to C, the same operation and evaluation as in Example 1 were performed. The results are shown in Table 2.
(Comparative Example 3)
The same operation and evaluation as in Example 3 were performed except that the heat treatment was not performed. The results are shown in Table 2.
Example 4
The same operation and evaluation as in Example 1 were performed except that the molding material A was changed to D. The results are shown in Table 2.
(Comparative Example 4)
The same operation and evaluation as in Example 4 were performed except that the heat treatment was not performed. The results are shown in Table 2.
(Example 5)
The same operation and evaluation as in Example 1 were performed except that the time for passing the film through warm water was changed from 60 seconds to 5 seconds. The results are shown in Table 2.
(Example 6)
The same operation and evaluation as in Example 1 were performed except that the time for passing the film through warm water was changed from 60 seconds to 10 seconds. The results are shown in Table 2.
(Example 7)
The same operation and evaluation as in Example 1 were performed except that the time for passing the film through warm water was changed from 60 seconds to 30 seconds. The results are shown in Table 2.
(Example 8)
The same operation and evaluation as in Example 1 were performed except that the time for passing the film through warm water was changed from 60 seconds to 90 seconds. The results are shown in Table 2.
Example 9
The same operation and evaluation as in Example 1 were performed except that the temperature of the hot water was changed from 80 ° C. to 60 ° C. and the time for passing the film through the hot water was changed from 60 seconds to 30 seconds. The results are shown in Table 2.
(Example 10)
The same operation and evaluation as in Example 9 were performed except that the time for passing the film through warm water was changed from 30 seconds to 60 seconds. The results are shown in Table 2.
(Example 11)
The same operation and evaluation as in Example 1 were performed except that the temperature of the hot water was changed from 80 ° C. to 70 ° C. and the time for passing the film through the hot water was changed from 60 seconds to 30 seconds. The results are shown in Table 2.
(Example 12)
The same operation and evaluation as in Example 11 were performed except that the time for passing the film through warm water was changed from 30 seconds to 60 seconds. The results are shown in Table 2.
(Example 13)
Since the film was passed through warm water as the heat treatment, the same operation and evaluation as in Example 1 were performed except that the film was brought into contact with the plurality of heat rolls shown in FIG. The results are shown in Table 2.
The temperature of rolls 10 to 19 in FIG. 3 was adjusted to 60 ° C. by dielectric heat generation, and the film was passed at a speed of 5 m / min. The heat treatment in this case was performed at 60 ° C. for 60 seconds.
In addition, the roll of FIG. 3 used by the present Example used the 1st-10th roll from the cast apparatus side installed in the longitudinal stretch machine of the multilayer extrusion, cast, and extending | stretching test apparatus by Musashinokikai.
(Example 14)
The same operation and evaluation as in Example 13 were performed except that the temperature of the roll was changed from 60 ° C. to 80 ° C. and the speed of passing the film was changed from 5 m / min to 10 m / min. The results are shown in Table 2.
(Example 15)
The same operation and evaluation as in Example 13 were performed except that the temperature of the roll was changed from 60 ° C to 80 ° C. The results are shown in Table 2.
(Example 16)
The same operation and evaluation as in Example 13 were performed except that the temperature of the roll was changed from 60 ° C. to 90 ° C. and the speed of passing the film was changed from 5 m / min to 10 m / min. The results are shown in Table 2.
(Example 17)
The same operation and evaluation as in Example 13 were performed except that the roll temperature was changed from 60 ° C to 90 ° C. The results are shown in Table 2.
(Example 18)
The same operation and evaluation as in Example 13 were performed except that the molding material A was changed to D. The results are shown in Table 2.
(Example 19)
The same operation and evaluation as in Example 18 were performed except that the temperature of the roll was changed from 60 ° C. to 80 ° C. and the speed of passing the film was changed from 5 m / min to 10 m / min. The results are shown in Table 2.
(Example 20)
The same operation and evaluation as in Example 18 were performed except that the temperature of the roll was changed from 60 ° C to 80 ° C. The results are shown in Table 2.
(Example 21)
The same operation and evaluation as in Example 13 were performed except that the molding material A was changed to E and the roll temperature was changed from 60 ° C to 80 ° C. The results are shown in Table 2.
(Example 22)
The same operation and evaluation as in Example 21 were performed except that the temperature of the roll was changed from 80 ° C. to 90 ° C. and the speed of passing the film was changed from 5 m / min to 10 m / min. The results are shown in Table 2.
(Example 23)
The same operation and evaluation as in Example 21 were performed except that the roll temperature was changed from 80 ° C to 90 ° C. The results are shown in Table 2.
(Comparative Example 5)
The same operation and evaluation as in Comparative Example 1 were performed except that the molding material A was changed to E. The results are shown in Table 2.
(Comparative Example 6)
The same operation and evaluation as in Example 1 were performed except that the temperature of the hot water was changed from 80 ° C. to 40 ° C. and the time for passing the film through the hot water was changed from 60 seconds to 120 seconds. The results are shown in Table 2.
(Comparative Example 7)
The same operation and evaluation as in Example 18 were performed except that the temperature of the roll was changed from 60 ° C. to 40 ° C. and the speed of passing the film was changed from 5 m / min to 1.66 m / min. The results are shown in Table 2.

In comparison between Examples 1 to 23 and Comparative Examples 1 to 5, it was confirmed that the phenomenon of tightening due to room temperature storage could be prevented by heat treatment. Moreover, from Examples 1 to 23, it was confirmed that the heat treatment was effective in either contact with the heat medium of the film or contact with the heating surface.

  The present invention is a method by which a polylactic acid-based plasticized film can be easily and efficiently produced by inflation molding, and the film produced in the present invention is suitably used as an agricultural multi-film, a food packaging bag, a garbage bag, etc. it can.

DESCRIPTION OF SYMBOLS 1 Base in inflation molding 2 Plasticized film expanded in inflation molding 3 Guide plate 4a Stretched plasticized film 4b Stretched plasticized film 4c Stretched plasticized film 4d Stretched plasticized film 5 Rolled-up plasticized film 6 Rolled plasticized film 7 Plasticized film stretched during rewinding 8 Rolled plasticized film 9 Rewinded and stored in storage Rolled plasticized film

Claims (10)

  A method for producing a polylactic acid-based resin plasticized film by molding a polylactic acid-based resin composition containing 10 to 30 parts by weight of a plasticizer with respect to 100 parts by weight of polylactic acid by an inflation molding method. A method for producing a polylactic acid-based resin plasticized film, comprising a step of heat treatment in a step after discharging the die.   The manufacturing method of Claim 1 whose said plasticizer is benzyl alkyl diglycol adipate.   The said heat processing is a manufacturing method of Claim 1 or 2 which is a method of making the shape | molded film contact the medium which is higher than 40 degreeC and 100 degrees C or less for 2 to 300 seconds.   The said heat processing is a manufacturing method of Claim 1 or 2 which is a method of making the shape | molded film contact the heating surface which is higher than 40 degreeC and is 100 degrees C or less for 2 to 300 seconds.   The manufacturing method according to any one of claims 1 to 4, wherein the heat treatment is performed during a process from discharging a die for inflation molding to first winding of the plasticized film.   The manufacturing method according to claim 1, wherein the heat treatment is performed after winding the plasticized film once after inflation molding.   The manufacturing method according to any one of claims 1 to 6, wherein the plasticized film is a plasticized film that is not wound even if maintained in a roll shape at 20 to 40 ° C.   The plasticized film according to any one of claims 1 to 7, wherein the plasticized film is a plasticized film that does not generate wrinkles and / or blocking even when maintained in a roll shape at 20 to 40 ° C. The manufacturing method as described.   In the method for producing a polylactic acid-based resin plasticized film by an inflation molding method, the step after the die discharge of the inflation molding includes a heat treatment step, Generation and / or blocking prevention method.   A polylactic acid-based resin plasticized film formed by an inflation molding method, characterized by not being tightened.