JP2002327107A - Polylactic acid-based film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polylactic acid-based film which has biodegradability, excellent flexibility and impact resistance, controls bleedout of a plasticizer and has excellent film-forming properties and printability. SOLUTION: A polylactic acid is mixed with a biodegradable aliphatic- aromatic copolyester having <=0 deg.C glass transition temperature in the range of (polylactic acid)/(biodegradable aliphatic-aromatic-copolyester) of 95/5-30/70 (mass %). The polylactic acid and the biodegradable aliphatic-aromatic copolyester in an amount of the total of 100 mass parts are mixed with 5-30 mass % of a plasticizer and 5-40 mass % of an inorganic filler to give a resin composition. The resin composition is heated and melted and made into a film by an inflation method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polylactic acid film excellent in bleed-out resistance and printability of a plasticizer.

[0002]

2. Description of the Related Art Films used as bags such as garbage bags, shopping bags, compost bags, and packaging materials for newspapers, magazines, foods, etc., have recently been subjected to biodegradation due to the growing social demands for environmental protection. It is desired to be formed of a conductive polymer. Among them, polylactic acid, which is widely present in nature and is harmless to animals, plants and humans, has a melting point of 140 to 175.
Since it is a thermoplastic resin having a sufficient heat resistance at ℃ and a relatively inexpensive, it is expected as a biodegradable polymer having excellent practicality.

However, films made of polylactic acid are inferior in flexibility and impact resistance, so that films suitable for practical use have not yet been obtained, and improvements in such physical properties have been demanded.

In order to improve the flexibility and impact resistance of a polylactic acid-based film, Japanese Patent No. 3105020 discloses a resin composition prepared by compounding a plasticizer with polylactic acid or lactic acid and another hydroxycarboxylic acid. There has been proposed a method of forming a film by promoting plasticization. However, in order to impart practical flexibility to the resin composition, a considerable amount of a plasticizer must be added to polylactic acid.
Originally, since very few plasticizers have good compatibility with polylactic acid, most plasticizers bleed out when a considerable amount of plasticizer was blended into a film as described above, resulting in the production of a film. Blocking occurs at the time of film, ink cannot be printed when printing the film,
Alternatively, there is a problem that even if printing can be performed, ink flows out.

On the other hand, Japanese Patent Application Laid-Open No. 9-111107 discloses a cup formed by vacuum molding using a sheet made of a polylactic acid-based polymer and a biodegradable aliphatic polyester having a glass transition temperature of 0 ° C. or less. I have. This cup is described as having excellent impact resistance. However, when the thickness of the sheet is small, such as bags such as garbage bags and compost bags, the impact strength is insufficient.

[0006] Japanese Patent Application Laid-Open No. 10-17756 discloses a method for improving the flexibility of a polylactic acid-based film without performing a stretching treatment by reacting a polyfunctional isocyanate compound with a composition comprising polylactic acid and an aliphatic polyester. Resin compositions have been proposed. However, since polylactic acid is a polymer having high rigidity, when the ratio of the polylactic acid component is high, there is a limit to the softening thereof.

Further, Japanese Patent Application Laid-Open No. 11-116788 discloses a film or sheet formed from a resin composition comprising polylactic acid, a biodegradable aliphatic polyester having a melting point of 80 to 250 ° C., and a plasticizer. JP-A-2000-273207 discloses a method for forming an inflation film from polylactic acid, a biodegradable aliphatic polyester having a glass transition temperature of 0 ° C. or lower, and a plasticizer. . In these methods, polylactic acid is blended with an aliphatic polyester that is more flexible than polylactic acid, and a plasticizer is further blended to impart flexibility and impact resistance to the polylactic acid-based film. Since the plasticizer compounded for the purpose of plasticization is also distributed to the aliphatic polyester having high crystallinity, the plasticizer distributed to the aliphatic polyester in the film forming process bleeds out and is printed on the film. At times, there is a problem that printing cannot be performed due to lack of ink, or ink flows out or peels off.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above problems, has biodegradability, is excellent in flexibility and impact resistance, suppresses bleed-out of a plasticizer, and forms films and prints. It is intended to provide a polylactic acid-based film having excellent characteristics.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have accomplished the present invention. That is, the present invention provides a resin composition comprising polylactic acid, a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or lower, a plasticizer, and an inorganic filler. The feature is a polylactic acid-based film as a feature. Further, polylactic acid and a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less are (polylactic acid) / (biodegradable aliphatic-aromatic copolymer polyester) = 95/5 to 30. / 70 (% by mass), the plasticizer is 1 to 30% by mass, and the inorganic filler is 100 parts by mass of the polylactic acid and the biodegradable aliphatic-aromatic copolymerized polyester in total. Is a method for producing a polylactic acid-based film in which a resin composition blended in a range of 0.5 to 40% by mass is heated and melted to form a film by an inflation method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polylactic acid-based film of the present invention is formed of a resin composition comprising polylactic acid, a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or lower, a plasticizer, and an inorganic filler. Need to be done. Biodegradability can be imparted to the film by using polylactic acid. Also,
By blending polylactic acid with a biodegradable aliphatic-aromatic copolymerized polyester having a glass transition temperature of 0 ° C. or less and a plasticizer, the polylactic acid has a property of being hard and brittle at room temperature and has flexibility and impact resistance. Property can be imparted. In addition, blending a plasticizer with polylactic acid alone makes it easier for the plasticizer to bleed out, but blending a biodegradable aliphatic-aromatic copolymer polyester having low crystallinity suppresses the bleed out of the plasticizer. As a result, good film-forming properties can be obtained, and good printability can be obtained without ink flowing out or peeling off even when printing is performed on the film. Further, the plasticity and the biodegradable aliphatic-aromatic copolymerized polyester reduce the crystallinity of the resin composition and soften it. However, in the present invention, since the inorganic filler is blended, the inorganic filler has a crystal nucleus. As an agent, good film-forming properties can be obtained, and also, suppression of blocking of the film at the time of film formation and provision of slipperiness can be realized.

In the present invention, the polylactic acid is a poly-L-lactic acid in which the structural unit of lactic acid is L-lactic acid, and the structural unit is D-lactic acid.
-Polylactic acid which is poly-D-lactic acid, poly-DL-lactic acid which is a copolymer of L-lactic acid and D-lactic acid, or a mixture thereof, and those having a number average molecular weight of 80,000 to 150,000 preferable.

Further, suppression of bleed-out of the plasticizer;
In consideration of ensuring film formation stability by crystallization of polylactic acid, it is preferable to use both crystalline polylactic acid and amorphous polylactic acid as the polylactic acid. Here, crystalline polylactic acid refers to a polylactic acid resin having a melting point in the range of 140 to 175 ° C, and amorphous polylactic acid refers to a polylactic acid resin having substantially no melting point. The mixing ratio of the crystalline polylactic acid and the amorphous polylactic acid is expressed by a mass ratio of (crystalline polylactic acid) /
(Amorphous polylactic acid) = 40/60 to 90/10 (% by mass). If the compounding ratio of the crystalline polylactic acid is less than 40% by mass, the crystallization of the polylactic acid is inferior, so that stable film formation cannot be performed. On the other hand, when the proportion of the crystalline polylactic acid exceeds 90% by mass, the plasticizer cannot be retained, and bleeding out of the plasticizer occurs during or after film formation.

The biodegradable aliphatic-aromatic copolymer polyester in the present invention uses an aromatic dicarboxylic acid as a component of the polyester, and its glass transition temperature is 0 ° C. or less in consideration of flexibility. Need to be.
When the glass transition temperature is higher than 0 ° C., sufficient flexibility cannot be imparted to the film.

In a conventional biodegradable aliphatic polyester,
Since the dicarboxylic acid component constituting the polyester was an aliphatic dicarboxylic acid, the melting point of the obtained resin was 100 ° C., which is considered to be a critical processing temperature in a general processing method.
Descended to the extent. In addition, when a large amount of a component such as adipic acid is copolymerized for the purpose of imparting flexibility, the melting point is further lowered and the processability of the resin is deteriorated. Did not. For this reason, the melting point of the aliphatic polyester resin obtained is lowered, but the crystallinity is not significantly reduced, and the resin becomes highly crystalline.When a plasticizer is added, the plasticizer cannot be sufficiently retained, and bleed out occurs. Was. However, since the biodegradable aliphatic-aromatic copolymer polyester used in the present invention also uses an aromatic dicarboxylic acid as a component of the polyester as described above, the aliphatic dicarboxylic acid which induces a decrease in melting point is used. Even when the copolymer is copolymerized in a larger amount than in the case of the aliphatic polyester, the melting point of the resin is maintained at about 100 ° C., without adversely affecting the processability of the resin, and furthermore, the crystallinity is significantly reduced, and the resin is very flexible. It is possible to design a resin that is suitable for its properties. As described above, the biodegradable aliphatic-aromatic copolymer polyester of the present invention is superior in flexibility to the conventionally used aliphatic polyester, the retention of the plasticizer is remarkably improved, and the bleed-out resistance is improved. Can be improved.

As the biodegradable aliphatic-aromatic copolymer polyester in the present invention, those obtained by condensing an aliphatic diol with an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid can be used. 25J / g
The following are preferred. If the heat of crystal fusion of the biodegradable aliphatic-aromatic copolyester exceeds 25 J / g, the plasticizer cannot be retained due to the decrease in the amorphous region due to the improvement in the crystallinity of the resin, and the bleed out of the plasticizer is remarkable. Become.

The aliphatic diol constituting such a biodegradable aliphatic-aromatic copolymerized polyester includes ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. As aromatic dicarboxylic acids, terephthalic acid,
Examples include isophthalic acid and naphthalenedicarboxylic acid, and examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanoic acid.
Then, the desired biodegradable aliphatic-aromatic copolymerized polyester is obtained by selecting and polycondensing one or more kinds of these, respectively, and can be crosslinked with a polyfunctional isocyanate compound, if necessary.

The plasticizer in the present invention functions by being distributed between the polylactic acid and the biodegradable aliphatic-aromatic polyester. When the biodegradable aliphatic-aromatic copolymerized polyester has high crystallinity, that is, a large heat of crystal fusion, the plasticizer bleeds out due to the excluded volume effect accompanying the crystallization and the absolute lack of the amorphous region. Occurs, making it difficult to hold the plasticizer in the resin. Therefore, although the heat of crystal fusion of the obtained resin differs depending on the copolymerization composition ratio of the aromatic dicarboxylic acid component and the aliphatic dicarboxylic acid component, in the present invention, as described above, the glass transition temperature is 0 ° C. or less. When the heat of crystal fusion of the aliphatic-aromatic polyester copolymer is 25 J / g or less, bleed out of the plasticizer can be suppressed.

The plasticizer in the present invention is compatible with polylactic acid and the biodegradable aliphatic-aromatic copolymerized polyester, is non-volatile, and is non-toxic from the viewpoint of environmental problems. FDA (Food and Drug Administ
ration). In particular,
An ether ester plasticizer and an oxy acid ester plasticizer. Specific examples of ether ester plasticizers include:
Bismethyldiethylene glycol adipate, bisbutyl diethylene glycol adipate and the like. Also,
Specific examples of oxyester plasticizers include tributyl acetylcitrate and the like.
More than one kind can be mixed and used.

The inorganic filler in the present invention functions as a nucleating agent and a lubricant. That is, simply adding a plasticizer to the resin component consisting of polylactic acid and the biodegradable aliphatic-aromatic copolymerized polyester lowers the melt tension of the film due to plasticization of the resin, thereby lowering the film-forming properties, Although blocking of the film or the like occurs, addition of an inorganic filler further suppresses blocking during film formation and imparts lubricity.

Examples of the inorganic filler in the present invention include common inorganic fillers such as talc, silica, calcium carbonate, magnesium carbonate, kaolin, mica, titanium oxide, aluminum oxide, zeolite, clay, and glass beads. Particularly, talc is preferable because it exhibits the most effect as a crystal nucleating agent for polylactic acid. An organic lubricant may be used in combination with the inorganic filler. Specific examples of the organic lubricant include liquid paraffin, microcrystalline wax, natural paraffin, aliphatic hydrocarbon lubricant such as synthetic paraffin, stearic acid, lauryl. Acids, hydroxystearic acid, fatty acid lubricants such as hardened castor oil, fatty acid amide lubricants such as erucamide, stearamide, oleamide, ethylenebissteaamide, ethylenebisoleamide, ethylenebislaurate amide, Fatty acids (partial) of polyhydric alcohols such as metal soap lubricants, which are metal salts of fatty acids having 12 to 30 carbon atoms, such as aluminum stearate, lead stearate, calcium stearate, and magnesium stearate, glycerin fatty acid esters, and sorbitan fatty acid esters. Ether-based lubricants, butyl stearate, and long chain ester wax is a fatty acid ester lubricant or a composite lubricant These were combined, such as montan wax.

The mixing ratio of the polylactic acid constituting the film of the present invention and the biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or lower is expressed by mass ratio of (polylactic acid)
/ (Biodegradable aliphatic-aromatic copolymerized polyester) = 9
It is preferable to be in the range of 5/5 to 30/70 (% by mass). When the content of the polylactic acid-containing component exceeds 95% by mass, the resulting film is inferior in flexibility, and the molecular weight decreases due to hydrolysis, so that the physical properties of the film are rapidly reduced. If the content of the polylactic acid-containing component is less than 30% by mass, the biodegradable aliphatic-aromatic copolymerized polyester component is mainly used, and the decomposition is slow. For this reason, the decomposition treatment by a compost device or the like is not preferable because the film may be entangled with the stirring blade and the compost device may be damaged. Therefore, the mixing ratio of polylactic acid and the biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less is (polylactic acid) / (biodegradable aliphatic-aromatic copolymer polyester) in mass ratio. = 80/20 to 50/50 (% by mass), more preferably 80/20 to 60 /
More preferably, it is 40 (% by mass).

The mixing ratio of the plasticizer is 100 in total of the polylactic acid and the biodegradable aliphatic-aromatic copolymer polyester.
It is preferable that the content is 1 to 30% by mass based on the mass part.
If the content of the plasticizer is less than 1% by mass, the glass transition temperature of the polylactic acid hardly decreases, so that the obtained film becomes cellophane-like and inferior in flexibility. It is not suitable for fields that require sex. On the other hand, if the content ratio of the plasticizer exceeds 30% by mass, the glass transition temperature of polylactic acid is too low, and the hydrolysis rate of the obtained film is rapidly accelerated, so that the product life is too short. Further, there is a problem that bleed-out of the plasticizer occurs and film blocking or printing failure occurs during film formation. Therefore, the mixing ratio of the plasticizer is more preferably 7 to 20% by mass.

The mixing ratio of the inorganic filler is 10% in total of polylactic acid and the biodegradable aliphatic-aromatic copolymer polyester.
It is preferably in the range of 0.5 to 40% by mass with respect to 0 parts by mass. When the content ratio of the inorganic filler is less than 0.5% by mass, the effect of the nucleating agent of the inorganic filler does not appear, so that the film formation becomes difficult due to insufficient melt tension of the film at the time of film formation. In addition, the film itself is inferior in slipperiness and blocking resistance, and may cause processing problems such as post-processing. On the other hand, when the content ratio of the inorganic filler exceeds 40% by mass, physical properties of the obtained film,
In particular, the tear strength, heat seal strength, and the like are significantly reduced, which is a practical problem. Therefore, the mixing ratio of the inorganic filler is preferably 10 to 30% by mass, and 10 to 20% by mass.
It is still more preferable that the content is mass%.

The resin composition constituting the polylactic acid-based film of the present invention may contain a crosslinking agent such as an organic peroxide and a crosslinking aid, if necessary, for the purpose of suppressing a decrease in melt tension during film formation. The resin composition may be subjected to mild crosslinking by using an agent in combination.

Specific examples of the crosslinking agent include n-butyl-
4,4-bis-t-butylperoxyvalerate, dicumyl peroxide, di-t-butyl peroxide,
Di-t-hexyl peroxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexane, 2,5
-Dimethyl-2,5-t-butylperoxyhexyne-
Organic peroxides such as 3, phthalic anhydride, maleic anhydride, trimethyladipic acid, trimellitic anhydride,
Polyvalent carboxylic acids such as 2,3,4-butanetetracarboxylic acid, metal complexes such as lithium formate, sodium methoxide, potassium propionate, and magnesium ethoxide; bisphenol A type diglycidyl ether;
-Epoxy compounds such as hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, terephthalic acid diglycidyl ester, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate And the like.

Specific examples of the crosslinking aid include glycidyl methacrylate, normal-butyl methacrylate, hydroxypropyl monomethacrylate, polyethylene glycol monomethacrylate and the like.

The resin composition constituting the polylactic acid film of the present invention may contain an ultraviolet ray inhibitor, a light stabilizer, an antifogging agent, an antifog agent, an antistatic agent, a flame retardant, Other additives such as agents, antioxidants, fillers and pigments can also be added.

Hereinafter, the method for producing the film of the present invention will be described with reference to an example. First, polylactic acid, a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler are blended in predetermined amounts, and melt-kneaded by a twin-screw kneading extruder. To produce compound pellets. After drying the compound pellets, a film is formed by an inflation film forming method. That is, the compound pellets after drying are put into a single-screw kneading extruder, and the molten polymer is pulled up into a tube shape from a round die, and simultaneously inflated into a balloon shape while air-cooled, or a molten polymer is formed from the round die. After being extruded in a cylindrical shape together with cooling water, it may be folded once, pulled up, and then expanded into a balloon while heating to form a film. The polymer melting temperature of the twin-screw kneading extruder is appropriately selected within a temperature range of 210 to 240 ° C. for the melting temperature of polylactic acid, and the melting temperature of the polymer of the compound pellet in the single-screw kneading extruder is L-lactic acid of polylactic acid Although the composition ratio of D-lactic acid, the glass transition temperature is 0 ° C. or less, the melting point and the blending amount of the biodegradable aliphatic-aromatic copolymerized polyester, and the blending amount of the plasticizer are selected in a timely manner. , 160 ° C to 200 ° C.

Incidentally, a cross-linking agent, a cross-linking auxiliary agent, an organic lubricant and the like can be added as needed at the time of preparing the compound pellets before the production of the polylactic acid-based film of the present invention. In addition, during the production of the film, an additive may be added to the extent that does not affect the physical properties of the film, if necessary.

[0030]

Next, the present invention will be specifically described based on examples, but the present invention is not limited to only these examples. In addition, the measurement of various physical property values in the following Examples and Comparative Examples was performed by the following methods. (1) Heat of crystal fusion (J / g): Using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer, a heating rate of 2 was used.
It was measured at 0 ° C./min and determined from the peak of the obtained melting endothermic curve. (2) Tensile strength (MPa) and tensile elongation (%): These are indicators of the impact resistance of a film, and are JIS K-
It was measured according to the method described in 7127. (3) Tensile modulus (GPa): It is an index of the flexibility of the film, and was measured according to the method described in JIS K-7127. (4) Impact strength (J / 0.03 mm): Using a film impact tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a measurement temperature of 23 ° C.
In an atmosphere of 50% RH, pendulum capacity 30 kg · cm, 1
It measured using the impact head of 2.7 mm (phi). (5) Bleeding property of plasticizer and blocking property of film: For a film produced by the inflation method, the bleeding property is 80 according to the method described in JIS Z0219.
The bleeding property of the plasticizer when held under a condition of 500 ° C. and a load of 500 g was evaluated as follows.

：: No bleed-out was observed. Δ: Slight bleed-out was observed. X: Bleed-out was noticeably observed. The blocking property of the film was evaluated as follows.

：: No blocking was observed. Δ: Slight blocking was observed. X: Completely blocked. (6) Printability: The film was printed with a flexographic printing machine and then dried with hot air at 40 ° C. . Then, length 50m
A cellophane tape having a width of 15 mm and a width of 15 mm was attached to the printing surface, and then the cellophane tape was peeled off, and the printability was evaluated as follows.

；: No ink was peeled off the cellophane tape at all ×: ink was slightly peeled off the cellophane tape Example 1 As polylactic acid, the content of D-lactic acid was 1.2 mol% and the weight average molecular weight was Is 200,000 crystalline polylactic acid (Cargill Dow: Nature Works) and amorphous polylactic acid (Cargill Dow) having a D-lactic acid content of 10 mol% and a weight average molecular weight of 200,000. (Manufactured by Nature Works) in an amount of 30% by mass.

Polybutylene adipate terephthalate having a heat of crystal fusion of 15 J / g as a biodegradable aliphatic-aromatic copolymer polyester having 60% by mass of polylactic acid and a glass transition temperature of -30 ° C. (manufactured by BASF: Ecoflex F) ) 40% by mass, and 100% by mass, 8% by mass of bismethyldiethylene glycol adipate (MXA, manufactured by Daihachi Chemical Co., Ltd.) as a plasticizer, and talc (Hayashi having an average particle size of 2.75 μm as a mineral filler) Kasei U
pu HST-0.5) and a twin-screw extrusion kneader (manufactured by Nippon Steel Works, model number TEX
44α) to obtain a polylactic acid-based compound raw material at an extrusion temperature of 230 ° C.

Next, this polylactic acid-based compound raw material was melt-extruded at a set temperature of 190 ° C. using a single screw extruder (manufactured by Tommy Machine Industry Co., Ltd.) having a screw diameter of 50 mm equipped with a circular die having a diameter of 100 mm. Then, the molten resin composition discharged from the die was formed into a tube-like film while being expanded by air pressure and simultaneously air-cooled by an air ring. The composition was formed into a film in an environment controlled at 25 to 30 ° C.

The tube-like film is picked up at a speed of 20 m / min by a pair of pinch rolls installed on the upper part of the die, and after a cooling time of about 7 seconds, the tube-like film is nip-pinched by the pinch rolls. And
Take up 100m by winding machine, thickness 30μ
m, a film having a film folding width of 250 mm was prepared.

Table 1 shows the physical properties and the like of the obtained film.

[0038]

[Table 1] Example 2 The plasticizer was changed to bisbutyl diethylene glycol adipate (BXA, manufactured by Daihachi Chemical Co., Ltd.). Otherwise, a film was produced in the same manner as in Example 1.

Table 1 shows the physical properties and the like of the obtained film. Example 3 The plasticizer was tributyl acetylcitrate (manufactured by Taoka Chemical Co., Ltd .:
ATBC), and the mixing ratio was 10% by mass. Otherwise, a film was produced in the same manner as in Example 1.

Table 1 shows the physical properties and the like of the obtained film. The films obtained in Examples 1 to 3, polylactic acid,
Since the glass transition temperature was formed from a resin composition containing a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler, the biodegradable fat described above was used. A film having excellent mechanical properties and having flexibility and impact resistance was obtained by using the aromatic-aromatic copolymerized polyester and the plasticizer. Further, a decrease in film-forming properties due to plasticization of the resin was suppressed by the inorganic filler compounded as a crystal nucleating agent, and good film-forming properties were obtained. further,
Bleed-out of the plasticizer could be suppressed by the biodegradable aliphatic-aromatic copolymerized polyester, and a film excellent in printability was obtained. Comparative Example 1 In place of the biodegradable aliphatic-aromatic copolymer polyester, polybutylene succinate adipate (Bionole # 3001 manufactured by Showa Kogyo Co., Ltd.), which is an aliphatic polyester having a heat of crystal fusion of 45 J / g, was used. Otherwise, a film was prepared in the same manner as in Example 1.

Table 1 shows the physical properties and the like of the obtained film. Comparative Example 2 A compound raw material was prepared by blending 20% by mass of a plasticizer and 25% by mass of an inorganic filler with respect to 100 parts by mass of polylactic acid without using a biodegradable aliphatic-aromatic copolymerized polyester. . The set temperature at which the compound material was melt-extruded was 175 ° C. Otherwise, a film was prepared in the same manner as in Example 1.

Table 1 shows the physical properties and the like of the obtained film. Comparative Example 3 A compound raw material was prepared without blending a plasticizer. Otherwise, a film was prepared in the same manner as in Example 1.

Table 1 shows the physical properties of the obtained film. Comparative Example 4 A compound raw material was prepared without blending an inorganic filler. Other than that, an attempt was made to produce a film in the same manner as in Example 1. However, the tube was not stable due to insufficient melt tension of the tube, causing unevenness in width, and the tubular film was nipped with a pinch roll. The subsequent film was blocked and could not be opened at all.

In Comparative Example 1, since the aliphatic polyester was used in place of the biodegradable aliphatic-aromatic copolymerized polyester, the crystallinity of the resin was increased, the plasticizer could not be sufficiently held, and bleed out occurred. The resulting film was inferior in impact resistance and printability.

In Comparative Example 2, since the biodegradable aliphatic-aromatic copolymerized polyester was not compounded, it was necessary to increase the amount of the plasticizer in order to impart flexibility to the film. The glass transition temperature of the film decreased with an increase in the blending amount. As a result, at room temperature or lower, hydrolysis of polylactic acid was promoted, and the mechanical properties of the film were significantly reduced with time. In addition, flexibility, impact resistance and printability were poor.

In Comparative Example 3, the obtained film was inferior in flexibility and impact resistance because no plasticizer was blended, and the wrinkles developed during tube nip were not recovered because the film was hard because the film was hard. The film had many wrinkles. In addition, printing omissions frequently occurred due to wrinkles on the film surface.

In Comparative Example 4, since no inorganic filler was blended, blocking was severe when pelletizing the compound raw material, and the pellets were formed using these pellets. Since the melt tension was insufficient, the tube was not stable, and width irregularity occurred. Further, the film after nipping the tube-shaped film with a pinch roll was blocked and could not be opened at all.

[0048]

According to the present invention, biodegradability can be imparted to a film by using polylactic acid. In addition, by blending a plasticizer with a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or lower, the polylactic acid having the property of being hard and brittle at room temperature has flexibility. Impact resistance can be imparted. Also, by blending a low-crystalline biodegradable aliphatic-aromatic copolymerized polyester with polylactic acid, bleed-out of the plasticizer is suppressed, and good film-forming properties are obtained by suppressing blocking during film-forming. Even when printing is performed on a film, good printability can be obtained without ink flowing out or peeling. Further, the plasticity and the biodegradable aliphatic-aromatic copolymerized polyester reduce the crystallinity of the resin composition and soften it. However, in the present invention, since the inorganic filler is blended, this inorganic filler is As a nucleating agent, good film-forming properties can be obtained, and blocking of the film at the time of film formation and imparting of lubricity can be realized.

Such a polylactic acid-based film comprises a polylactic acid and a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less in a mass ratio of (polylactic acid) / (biodegradable aliphatic). -Aromatic copolymerized polyester) = 95/5
The plasticizer is blended in an amount of from 30 to 70% by mass, and a plasticizer is used in an amount of 1 to 30% by mass based on 100 parts by mass of the polylactic acid and the biodegradable aliphatic-aromatic copolymerized polyester in total. Can be easily obtained by heating and melting a polymer blended in a range of 0.5 to 40% by mass into a film by an inflation method.

Therefore, the polylactic acid-based film of the present invention
Bags from relatively thin bags to heavy bags such as garbage bags, shopping bags, compost bags, fertilizer bags, rice bags, newspaper / magazine packaging, vegetable packaging, food packaging, disposable diapers and sanitary materials Packaging materials such as packaging film, wrap film used for packaging, pocket tissue,
Used for a wide range of applications such as paper laminating materials, sealant materials, disposable diapers and sanitary material backsheets, disposable gloves, horticultural house exterior and lining materials, tunnel houses, multi-film and other agricultural films. Becomes possible.

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Claims (6)

[Claims] 1. A resin composition comprising polylactic acid, a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or lower, a plasticizer, and an inorganic filler. Polylactic acid based film. 2. The blending ratio of polylactic acid and a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less is (polylactic acid) / (biodegradable aliphatic-aromatic copolymer polyester). ) = 95/5 to 30/70 (% by mass), and based on 100 parts by mass of the polylactic acid and the biodegradable aliphatic-aromatic copolymerized polyester in total.
1 to 30% by mass of plasticizer, 0.5 to 40 of inorganic filler
The polylactic acid-based film according to claim 1, wherein the polylactic acid-based film is blended in a range of mass%. 3. The polylactic acid-based film according to claim 1, wherein the biodegradable aliphatic-aromatic copolymerized polyester has a heat of crystal fusion of 25 J / g or less. 4. The plasticizer is an ether ester plasticizer,
At least one selected from oxyester plasticizers
The polylactic acid-based film according to claim 1 or 2, which is a seed. 5. The polylactic acid-based film according to claim 4, wherein the plasticizer is at least one selected from bismethyldiethylene glycol adipate, bisbutyl diethylene glycol adipate, and tributyl acetylcitrate. 6. Polylactic acid and a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less are (polylactic acid) / (biodegradable aliphatic-aromatic copolymer polyester) = 95 / 5-30 / 70 (% by mass), the plasticizer is 1-30% by mass based on 100 parts by mass of the polylactic acid and the biodegradable aliphatic-aromatic copolymerized polyester in total. 0.5 to 40% by mass of inorganic filler
A method for producing a polylactic acid-based film, which comprises heating and melting a resin composition blended in the range described above to form a film by an inflation method.