JP3510218B2 - Polylactic acid based film and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polylactic acid-based film having excellent plasticizer bleed-out resistance and printability.

[0002]

BACKGROUND OF THE INVENTION Bags such as garbage bags, shopping bags, compost bags, and films used as packaging materials for newspapers, magazines, foods, etc. are biodegradable with the recent increasing social demand for environmental protection. It is desired to be formed of a hydrophilic polymer. Among them, polylactic acid, which exists widely in nature and is harmless to animals and plants and humans and animals, has a melting point of 140 to 175.
Since it is a relatively low-priced thermoplastic resin while having a temperature of 0 ° C and sufficient heat resistance, it is expected as a biodegradable polymer having excellent practicality.

However, since a film made of polylactic acid is inferior in flexibility and impact resistance, a film suitable for practical use has not yet been obtained, and improvement of such physical properties is required.

Therefore, in Japanese Patent No. 3105020, in order to improve the flexibility and impact resistance of a polylactic acid-based film, a resin composition containing polylactic acid or lactic acid and another hydroxycarboxylic acid containing a plasticizer is disclosed. A method of promoting plasticization to form a film has been proposed. However, in order to give the resin composition flexibility suitable for practical use, a considerable amount of a plasticizer must be added to polylactic acid, and further,
Originally, there are very few plasticizers that have good compatibility with polylactic acid, so if you mix a large amount of plasticizers into a film as described above, most of the plasticizers will bleed out, and Blocking occurs at the time of film, ink can not be printed at the time of film printing,
Alternatively, there is a problem that the ink flows out even if printing is possible.

On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 9-111107 discloses a cup vacuum-formed using a sheet made of a polylactic acid polymer and a biodegradable aliphatic polyester having a glass transition temperature of 0 ° C. or lower. There is. Although this cup is described as having excellent impact resistance, its impact strength is insufficient when the sheet is thin, such as dust bags and compost bags.

Further, Japanese Patent Laid-Open No. 10-17756 discloses a method of improving the flexibility of a polylactic acid film without stretching it by reacting a polyfunctional lactic acid and an aliphatic polyester with a polyfunctional isocyanate compound. A resin composition prepared by the above method has been proposed. However, since polylactic acid is a polymer having high rigidity, there is a limit to the softening when the ratio of the polylactic acid component is high.

Further, in Japanese Patent Laid-Open No. 11-116788, a film or sheet formed of a resin composition composed of 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 of 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 softer than polylactic acid, and a plasticizer is further blended to impart flexibility and impact resistance to the polylactic acid film. Since the plasticizer compounded for the purpose of plasticization is distributed to the highly crystalline aliphatic polyester as well, the plasticizer distributed to the aliphatic polyester bleeds out during the film formation process and prints on the film. Occasionally, there is a problem that ink cannot be printed because it is out of ink, or that ink flows out or peels off.

[0008]

The present invention solves the above problems, has biodegradability, is excellent in flexibility and impact resistance, and suppresses bleeding out of a plasticizer to form a film or printability. It is intended to provide a polylactic acid-based film having excellent properties.

[0009]

The present inventors have achieved the present invention as a result of intensive studies to solve the above problems. That is, the present invention relates to polylactic acid and glass transition.
Biodegradable Aliphatic-Aromatic Copolymer
The blending ratio with steal is (polylactic acid) / (biodegradable fat)
Group-aromatic copolyester) = 95/5 to 30/7
It is in the range of 0 (mass%), and the polylactic acid and biodegradation
10 with the combined aliphatic-aromatic copolyester
1 to 30 mass% of plasticizer, 0% by mass, inorganic filling
The gist is a polylactic acid-based film characterized in that the material is blended in a range of 0.5 to 40% by mass . Further, polylactic acid and a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less are (polylactic acid) / (biodegradable aliphatic-aromatic copolyester)
= 95/5 to 30/70 (mass%) in the range,
1 part of the plasticizer is added to 100 parts by mass of the polylactic acid and the biodegradable aliphatic-aromatic copolyester.
-30% by mass, a resin composition containing an inorganic filler in the range of 0.5 to 40% by mass is heated and melted, and a method for producing a polylactic acid-based film is formed by an inflation method. is there.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The polylactic acid-based film of the present invention is formed of a polylactic acid, a resin composition containing a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler. Needs to be done. Biodegradability can be imparted to the film by using polylactic acid. Also,
By blending polylactic acid with a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or lower and a plasticizer, polylactic acid having properties of being hard and brittle at room temperature has flexibility and impact resistance. It can be imparted with sex. In addition, the plasticizer tends to bleed out only by adding the plasticizer to the polylactic acid, but the bleed-out of the plasticizer is suppressed by adding the biodegradable aliphatic-aromatic copolyester having low crystallinity. Therefore, good film-forming property can be obtained, and good printability can be obtained without the ink flowing out or peeling off even when the film is printed. Further, the plasticizer and the biodegradable aliphatic-aromatic copolyester decrease the crystallinity of the resin composition and soften, but since the inorganic filler is blended in the present invention, this inorganic filler has crystal nuclei. As an agent, good film-forming properties can be obtained, and blocking of the film at the time of film-forming and slipperiness can be provided.

As the polylactic acid in the present invention, the polylactic acid whose structural unit is lactic acid is L-lactic acid, and the structural unit is D
-Poly D-lactic acid, which is 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 are listed. 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 crystalline polylactic acid and amorphous polylactic acid in combination as the polylactic acid. The crystalline polylactic acid referred to here means a polylactic acid resin having a melting point in the range of 140 to 175 ° C., and the amorphous polylactic acid means a polylactic acid resin having substantially no melting point. The mixing ratio of crystalline polylactic acid and amorphous polylactic acid is (crystalline polylactic acid) / mass ratio.
(Amorphous polylactic acid) is preferably in the range of 40/60 to 90/10 (mass%). If the blending ratio of the crystalline polylactic acid is less than 40% by mass, the crystallization of the polylactic acid is poor and stable film formation cannot be performed. On the other hand, when the proportion of crystalline polylactic acid exceeds 90% by mass, the plasticizer cannot be retained, and bleed-out of the plasticizer occurs during or after film formation.

The biodegradable aliphatic-aromatic copolyester in the present invention uses an aromatic dicarboxylic acid as a constituent component of the polyester, and its glass transition temperature is 0 ° C. or lower in consideration of flexibility. Need to be
If the glass transition temperature is higher than 0 ° C., it becomes impossible to impart sufficient flexibility to the film.

In the conventional biodegradable aliphatic polyester,
Since the dicarboxylic acid component constituting the polyester was an aliphatic dicarboxylic acid, the melting point of the obtained resin is 100 ° C. which is considered to be the critical processing temperature in a general processing method.
It fell to the extent. Further, 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, so that the component for the purpose of imparting flexibility cannot be copolymerized too much. There wasn't. Therefore, the melting point of the obtained aliphatic polyester resin is lowered, but the crystallinity does not decrease so much to become a highly crystalline resin, and when the plasticizer is added, the plasticizer cannot be sufficiently retained and bleeding out occurs. It was However, since the biodegradable aliphatic-aromatic copolyester used in the present invention also uses an aromatic dicarboxylic acid as a constituent component of the polyester as described above, an aliphatic dicarboxylic acid that induces a melting point decrease is used. Even if it is copolymerized in a larger amount than in the case of aliphatic polyester, the melting point of the resin remains around 100 ° C, it does not adversely affect the processability of the resin, and it significantly reduces the crystallinity and is very flexible. It is possible to design a resin that is suitable for its characteristics. As described above, the biodegradable aliphatic-aromatic copolyester of the present invention is more flexible than the conventionally used aliphatic polyester, the retention of the plasticizer is significantly improved, and the bleed-out resistance is improved. Can be improved.

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

Examples of the aliphatic diol which constitutes such a biodegradable aliphatic-aromatic copolyester include ethylene glycol, propylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol. As the aromatic dicarboxylic acid, terephthalic acid,
Examples thereof include isophthalic acid and naphthalenedicarboxylic acid, and examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid and the like.
The desired biodegradable aliphatic-aromatic copolyester can be obtained by polycondensing one or more selected from these, 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 crystallinity of the biodegradable aliphatic-aromatic copolyester is high, that is, when the heat of fusion of crystal is large, the excluded volume effect due to this crystallization and the absolute lack of the amorphous region cause bleeding out of the plasticizer. Occurs, and it becomes difficult to retain 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 biodegradability at the glass transition temperature of 0 ° C. or lower is Bleeding out of the plasticizer can be suppressed by setting the heat of crystal fusion of the aliphatic-aromatic polyester copolymer to 25 J / g or less.

The plasticizer used in the present invention is compatible with polylactic acid and biodegradable aliphatic-aromatic copolyester, is non-volatile, is nontoxic from the viewpoint of environmental problems, etc. Furthermore, FDA (Food and Drug Administ)
Those that have passed the ration) are preferable. In particular,
These are ether ester plasticizers and oxyacid ester plasticizers. Specific examples of the ether ester plasticizer include:
Examples thereof include bismethyldiethylene glycol adipate and bisbutyldiethylene glycol adipate. Also,
Specific examples of the oxyester plasticizer include tributyl acetyl citrate and the like.
It is also possible to use a mixture of more than one type.

The inorganic filler in the present invention functions as a crystal nucleating agent and a lubricant. That is, only by adding a plasticizer to the resin component composed of polylactic acid and a biodegradable aliphatic-aromatic copolyester, the melt tension of the film is lowered with the plasticization of the resin to reduce the film formability, Although film blocking occurs, the addition of an inorganic filler can suppress blocking during film formation and impart slipperiness.

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. In particular, 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 this inorganic filler, and specific examples of the organic lubricant include, for example, liquid hydrocarbon, microcrystalline wax, natural paraffin, synthetic paraffin, and other aliphatic hydrocarbon lubricants, stearic acid, and lauryl. Fatty acid type lubricants such as acids, hydroxystearic acid, hydrogenated castor oil, erucic acid amides, stearic acid amides, oleic acid amides, ethylenebisstearic acid amides, ethylenebisoleic acid amides, ethylenebislauric acid amides and the like, Metal soap lubricants, which are fatty acid metal salts having 12 to 30 carbon atoms such as aluminum stearate, lead stearate, calcium stearate, and magnesium stearate, fatty acid (partial) of polyhydric alcohol such as glycerin fatty acid ester, sorbitan fatty acid ester. 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 polylactic acid constituting the film of the present invention and the biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less are mixed in a mass ratio of (polylactic acid).
/ (Biodegradable aliphatic-aromatic copolyester) = 9
Range Der 5 / 5-30 / 70 (weight%) Ru. When the content of the polylactic acid-containing component exceeds 95% by mass, the obtained film is inferior in flexibility, and the molecular weight is lowered by hydrolysis, so that the remarkable deterioration of the physical properties of the film is rapidly accelerated.
When the polylactic acid-containing component is less than 30% by mass, the biodegradable aliphatic-aromatic copolyester component becomes the main component,
Disassembly is slow. For this reason, the decomposition process using a composting device or the like is not preferable because the film may be entangled with the stirring blades and damage the composting device. Therefore, the compounding ratio of the polylactic acid and the biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less is (polylactic acid) / (biodegradable aliphatic-aromatic copolyester) in a mass ratio. = 80/20 to 50/50 (mass%) is more preferable, and 80/20 to 60/40 (mass%) is further preferable.

The blending ratio of the plasticizer is 100 in total of polylactic acid and biodegradable aliphatic-aromatic copolyester.
To parts by weight, Ru 1-30% by mass. When the content ratio of the plasticizer is less than 1% by mass, the glass transition temperature of polylactic acid is hardly decreased, and thus the obtained film becomes cellophane-like and is inferior in flexibility, and is flexible in bags and mulch films. 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 excessively lowered and the hydrolysis rate of the obtained film is rapidly accelerated, resulting in too short product life. Further, bleeding out of the plasticizer occurs, which causes problems such as film blocking during film formation and defective printing. Therefore, the blending 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 biodegradable aliphatic-aromatic copolyester.
It is in the range of 0.5 to 40 mass% with respect to 0 mass part. When the content ratio of the inorganic filler is less than 0.5% by mass, the effect of the crystal nucleating agent of the inorganic filler does not appear, so that film formation becomes difficult due to insufficient melt tension of the film during film formation. In addition, the film itself is inferior in slipperiness and blocking resistance, and processing problems such as post-processing may occur. On the other hand, the content ratio of the inorganic filler is 40% by mass.
If it exceeds, physical properties of the obtained film, particularly tear strength, heat seal strength and the like are remarkably deteriorated, which poses a practical problem. Therefore, the blending ratio of the inorganic filler is preferably 10 to 30% by mass, and more preferably 10 to 20% by mass.

The resin composition constituting the polylactic acid-based film of the present invention contains a crosslinking agent such as an organic peroxide and a crosslinking promoter, if necessary, for the purpose of suppressing the decrease in melt tension during film formation. The resin composition may be used in combination to give a slight degree of crosslinking to the resin composition.

Specific examples of the cross-linking agent include n-butyl-
4,4-bis-t-butylperoxyvalerate, dicumyl peroxide, di-t-butylperoxide,
Di-t-hexyl peroxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexane, 2,5
-Dimethyl-2,5-t-butylperoxyhexyne-
3, such as organic peroxides, phthalic anhydride, maleic anhydride, trimethyladipic acid, trimellitic anhydride, 1,
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, 1,6
-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 Isocyanate compounds such as

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

Further, the resin composition constituting the polylactic acid type film of the present invention contains an anti-ultraviolet agent, a light stabilizer, an antifogging agent, an antifog agent, an antistatic agent, a flame retardant, an anti-coloring agent depending on the use. Additives other than the above, such as agents, antioxidants, fillers and pigments can also be added.

The method for producing the film of the present invention will be described below with reference to an example. First, polylactic acid, a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler are mixed in predetermined amounts, and melt-kneaded by a biaxial kneading extruder. , Make compound pellets. After drying the compound pellets, a film is formed by an inflation film forming method. That is, the dried compound pellets are put into a single-screw kneading extruder, the molten polymer is pulled up from a round die into a tube shape, and while being air-cooled, it is inflated into a balloon shape at the same time to form a film, or the molten polymer is melted from a round die. It is possible to employ a method in which the resin is extruded downward together with cooling water into a cylindrical shape, then folded once, pulled up upward, and then inflated into a balloon while heating to form a film / film. The polymer melting temperature of the twin-screw kneading extruder is appropriately selected in the temperature range of polylactic acid of 210 to 240 ° C., and the melting temperature of the polymer of the compound pellets of the single-screw kneading extruder is the same as that of L-lactic acid of polylactic acid. The composition ratio of D-lactic acid, the melting point and blending amount of the biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less, and the blending amount of the plasticizer are appropriately selected in consideration of the time, , 160 ° C. to 200 ° C. temperature range.

If necessary, a cross-linking agent, a cross-linking aid, an organic lubricant, etc. may be added during the production of the compound pellets in the pre-stage of producing the polylactic acid-based film of the present invention. In addition, at the time of producing the film, additives may be added, if necessary, to such an extent that the physical properties of the film are not affected.

[0030]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In addition, the measurement of various physical properties in the following Examples and Comparative Examples was performed by the following methods. (1) Crystal fusion heat (J / g): Using a differential scanning calorimeter DSC-7 type manufactured by Perkin Elmer Co., Ltd., a heating rate of 2
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 film's impact resistance, and JIS K-
It measured according to the method of 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.), measuring temperature 23 ° C.,
Pendulum capacity 30 kg · cm in an atmosphere of 50% RH, 1
The measurement was performed using a 2.7 mmΦ impact head. (5) Bleedability of plasticizer and blocking property of film: For the film produced by the inflation method, 80 according to the method described in JIS Z0219.
The bleeding property of the plasticizer when kept under conditions of ° C and a load of 500 g was evaluated as follows.

◯: No bleed-out was observed Δ: Some bleed-out was observed ×: Remarkable bleed-out was observed Further, the blocking property of the film was evaluated as follows.

◯: No blocking was observed Δ: Some blocking was observed ×: Complete blocking (6) Printability: The film was printed with a flexographic printing machine and then dried with hot air at 40 ° C. . After that, 50m long
A cellophane tape having a width of m 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 on the cellophane tape ×: Ink was peeled off on the cellophane tape at all Example 1 As polylactic acid, the content of D-lactic acid was 1.2 mol% and the mass average molecular weight was 70% by weight of crystalline polylactic acid (Nature Works manufactured by Cargill Dow Co., Ltd.) having a content of 200,000, and amorphous polylactic acid having a content of D-lactic acid of 10 mol% and a mass average molecular weight of 200,000 (Cargill Dow). (Manufactured by: Nature Works) 30% by mass was used.

Polybutylene adipate terephthalate (manufactured by BASF: Ecoflex F) having a heat of crystal fusion of 15 J / g as a biodegradable aliphatic-aromatic copolyester having 60% by mass of polylactic acid and a glass transition temperature of -30 ° C. ) 40 mass% combined with 100 mass parts, bismethyldiethylene glycol adipate (manufactured by Daihachi Chemical Co., Ltd .: MXA) 8 mass% as a plasticizer, and talc having an average particle size of 2.75 μm as an inorganic filler (Hayashi) U made by Kaseisha
pu HST-0.5) 15 mass% is mixed and weighed, and a twin-screw extrusion kneader (manufactured by Japan Steel Works, model number TEX) is used.
44α) was melt-kneaded to produce 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 uniaxial extruder (manufactured by Tommy Kikai Co., Ltd.) with a screw diameter of 50 mm equipped with a circular die having a diameter of 100 mm. The molten resin composition discharged from the die was expanded by air pressure and simultaneously formed into a tubular film while being air-cooled by an air ring. The composition was formed into a film in an environment where the temperature was adjusted to 25 to 30 ° C.

This tube-shaped film was taken up at a speed of 20 m / min by a set of pinch rolls installed on the upper part of the die, and after a cooling time of about 7 seconds, the tube-shaped film was nipped by the pinch rolls. Then
Take up 100m with a winder and have a thickness of 30μ
m, and the film folding width was 250 mm.

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

[0038]

[Table 1] Example 2 The plasticizer was changed to bisbutyldiethylene glycol adipate (manufactured by Daihachi Chemical Co., Ltd .: BXA). A film was produced in the same manner as in Example 1 except for the above.

Table 1 shows the physical properties and the like of the obtained film. Example 3 A plasticizer was tributyl acetyl citrate (Taoka Chemical Co., Ltd .:
ATBC) and its blending ratio was 10% by mass. A film was produced in the same manner as in Example 1 except for the above.

Table 1 shows the physical properties and the like of the obtained film. The films obtained in Examples 1 to 3 were polylactic acid,
Since it was formed of a resin composition containing a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler, the above-mentioned biodegradable fat A film having excellent mechanical properties, flexibility and impact resistance was obtained by the group-aromatic copolyester and the plasticizer. Further, the deterioration of the film-forming property due to the plasticization of the resin was suppressed by the inorganic filler blended as the crystal nucleating agent, and the good film-forming property was obtained. further,
The biodegradable aliphatic-aromatic copolyester can suppress the bleed-out of the plasticizer, and a film having excellent printability was obtained. Comparative Example 1 Instead of the biodegradable aliphatic-aromatic copolyester, polybutylene succinate adipate (Bionole # 3001 manufactured by Showa High Polymer Co., Ltd.), which is an aliphatic polyester having a crystal fusion heat of 45 J / g, was used. A film was prepared in the same manner as in Example 1 except for the above.

Table 1 shows the physical properties and the like of the obtained film. Comparative Example 2 A compound raw material was prepared by using 20 parts by mass of a plasticizer and 25 parts by mass of an inorganic filler with respect to 100 parts by mass of polylactic acid without using a biodegradable aliphatic-aromatic copolyester. . Further, the set temperature for melt-extruding the compound raw material was 175 ° C. A film was prepared in the same manner as in Example 1 except for the above.

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. A film was prepared in the same manner as in Example 1 except for the above.

Table 1 shows the physical properties of the obtained film. Comparative Example 4 A compound raw material was prepared without blending the inorganic filler. A film was produced in the same manner as in Example 1 except for the above, but the tube was not stable due to insufficient melt tension of the tube and a width unevenness was generated, and the tube-shaped film was nipped by a pinch roll. The latter 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 copolyester, the crystallinity of the resin was high, the plasticizer could not be sufficiently retained, and bleed-out was exhibited. The obtained film was inferior in impact resistance and printability.

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

In Comparative Example 3, since no plasticizer was blended, the obtained film was inferior in flexibility and impact resistance, and wrinkles developed at the time of tube nip were not recovered because the film was hard, and thus obtained. The film had many wrinkles. In addition, wrinkles on the surface of the film caused frequent print defects.

In Comparative Example 4, since the inorganic filler was not mixed, blocking was violent when pelletizing the compound raw material, and it was attempted to form a film by using this pellet. Since the melt tension was insufficient, the tube was not stable and width unevenness was generated, and the film after the tube-shaped film was nipped by 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 polylactic acid with a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less and a plasticizer, polylactic acid having the property of being hard and brittle at room temperature can be made flexible. It is possible to impart impact resistance. Further, by blending polylactic acid with a low-crystalline biodegradable aliphatic-aromatic copolyester, the bleed-out of the plasticizer is suppressed, and blocking during film formation is suppressed to obtain good film formability. Even if the film is printed, good printability can be obtained without the ink flowing out or coming off. Further, the plasticizer and the biodegradable aliphatic-aromatic copolyester softens the crystallinity of the resin composition is lowered, but since the inorganic filler is blended in the present invention, this inorganic filler is crystallized. It serves as a nucleating agent and has good film-forming properties. Further, it is possible to suppress blocking of the film during film formation and to impart slipperiness.

Such a polylactic acid-based film comprises polylactic acid and a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less in a mass ratio of (polylactic acid) / (biodegradable aliphatic -Aromatic copolyester) = 95/5
To 30/70% by mass, and 1 to 30% by mass of a plasticizer and 100% by mass of the polylactic acid and the biodegradable aliphatic-aromatic copolyester in total, and an inorganic filler. It can be easily obtained by heating and melting a polymer compounded in a range of 0.5 to 40 mass% and forming a film by an inflation method.

Therefore, the polylactic acid-based film of the present invention is
Bags ranging from relatively thin bags such as garbage bags, shopping bags, compost bags, fertilizer bags, rice bags to heavy bags, newspaper / magazine packaging, vegetable packaging, food packaging, disposable diapers and sanitary materials. Wrapping, packaging film used for pocket tissues, wrapping film and other packaging materials,
It can be used for a wide range of applications such as laminated materials with paper, sealant materials, disposable diapers and back sheets for sanitary materials, disposable gloves, exterior and interior linings for greenhouse gardening houses, tunnel houses, agricultural films such as mulch film, etc. Is possible.

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Claims (5)

(57) [Claims] 1. Polylactic acid and glass transition temperature below 0 ° C.
Blending ratio with biodegradable aliphatic-aromatic copolyester
(Polylactic acid) / (biodegradable aliphatic-aromatic copolymerization
Polyester) = 95/5 to 30/70 (% by mass)
And the polylactic acid and the biodegradable aliphatic-aromatic
To 100 parts by mass combined with the copolyester,
1 to 30 mass% of plasticizer, 0.5 to 40 of inorganic filler
Poly milk characterized by being mixed in the range of mass%
Acid film. 2. Biodegradable aliphatic-aromatic copolymerized polyester
The crystal heat of fusion of tellur is 25 J / g or less.
The polylactic acid based film. 3. The plasticizer is an ether ester plasticizer,
At least one selected from oxyester plasticizers
The poly according to claim 1 or 2, which is a seed.
Lactic acid based film. 4. The plasticizer is bismethyldiethyleneglycol
Adipate, bisbutyldiethylene glycol adipate
Small amount selected from pete and tributyl acetylcitrate
4. The method according to claim 3, wherein the type is at least one.
Re-lactic acid type film. 5. Polylactic acid and glass transition temperature below 0 ° C.
Biodegradable aliphatic-aromatic copolyester
Lactic acid) / (biodegradable aliphatic-aromatic copolymer polyester
Blended in the range of 95/5 to 30/70 (mass%)
The polylactic acid and the biodegradable aliphatic-aromatic copolymer
Plasticizer for 100 parts by weight of polyester
Is 1 to 30% by mass, and the inorganic filler is 0.5 to 40% by mass.
The resin composition blended in the range of
Polylactic acid film that is formed into a film by the aeration method
Manufacturing method.