JP2003064245A - Biodegradable film or sheet, and molding product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable film or sheet having superior mechanical properties such as impact resistance and proper moldability, and a molding product using the same. SOLUTION: This biodegradable film or sheet is formed by using a resin composition that comprises a biodegradable aliphatic-aromatic copolymerized polyester having a glass transition temperature of 0 deg.C or less and poly(lactic acid) as main components.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable film or sheet, and a molded product using the same.

[0002]

BACKGROUND ART Plastics such as polyethylene, polypropylene, polyethylene terephthalate, and polyvinyl chloride have been conventionally used for stretch films for packing newspapers, magazines, foods, soundproof sheets, and the like. These films and sheets are discarded after their use, but if incinerated, the heat generated during combustion is high and may damage the incinerator during the process. Some are difficult to burn due to their extinguishability. Therefore, waste disposal by landfill is generally carried out, but these plastics remain without being decomposed due to their chemical and biological stability, so the social demand for environmental conservation has increased in recent years. Therefore, it is desired to be formed of a biodegradable polymer.

Polylactic acid is known as such a biodegradable polymer. However, since polylactic acid is hard and brittle, a film or sheet made of polylactic acid has poor impact resistance and can be used. There is a problem that the fields are limited. Further, a molded product obtained by processing a film or sheet made of polylactic acid is deformed when left to stand at high temperature and high humidity, and has a problem that it has poor wet heat resistance.

In order to solve such a problem, Japanese Patent No. 3138196, Japanese Patent Laid-Open No. 11-124430 and Japanese Patent Laid-Open No. 2000-191895 propose methods for mixing polylactic acid with an aliphatic polyester. However, there is a limit to the improvement of impact resistance only by blending the aliphatic polyester, and it is possible to improve the physical properties by increasing the blending ratio of the aliphatic polyester more than that of polylactic acid. However, the cost of the aliphatic polyester is high, resulting in high cost.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, is excellent in mechanical properties such as impact resistance, and has excellent moldability, and a biodegradable film or sheet, and a molded product using these. Is provided.

[0006]

The present inventors have achieved the present invention as a result of intensive studies to solve the above problems. That is, the present invention has a glass transition temperature of 0 ° C.
The following biodegradable aliphatic-aromatic copolyester,
A gist of the present invention is a biodegradable film or sheet comprising a resin composition containing polylactic acid as a main component.

A gist of the present invention is a molded article characterized by comprising these biodegradable films or sheets.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The biodegradable film or sheet of the present invention needs to be formed of a resin composition containing a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or lower and polylactic acid as main components. is there. Since the glass transition temperature is 0 ° C. or lower, both the biodegradable aliphatic-aromatic copolyester and the polylactic acid have biodegradability, and thus the used film or sheet can be appropriately disposed of. Further, a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or lower is a resin having excellent flexibility, but when this aliphatic-aromatic copolyester is used alone, a film or sheet is formed. Since the non-slip property is poor, by blending this aliphatic-aromatic copolyester with polylactic acid, the moldability in forming a film or sheet can be improved. Further, polylactic acid has properties of being hard and brittle at room temperature, but when used together with an aliphatic-aromatic copolyester, the film can be imparted with flexibility and impact resistance.

The film as used in the present invention has a thickness of less than 0.15 mm, and the sheet has a thickness of 0.15 mm or more. The aliphatic / aromatic copolyester in the present invention is a copolyester composed of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an aliphatic diol as at least constituents, and its glass transition temperature is 0 ° C or lower. It is necessary to be present, and more preferably -20 ° C or lower. When the glass transition temperature exceeds 0 ° C., when formed into a film or sheet, it lacks flexibility at room temperature, resulting in poor impact resistance.

As the aliphatic dicarboxylic acid, succinic acid,
Examples thereof include adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Further, as the aromatic dicarboxylic acid,
Examples thereof include terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid. Furthermore, as the aliphatic diol,
Ethylene glycol, propylene glycol, 1,4-
Examples include butanediol and 1,4-cyclohexanedimethanol. Then, at least one or more of these are selected and polycondensed to obtain the desired aliphatic / aromatic copolyester, and if necessary,
It is also possible to use an isocyanate, an acid anhydride, an epoxy compound, an organic peroxide or the like to provide jump-up and long-chain branching in structure.

Further, since the biodegradable copolyester contains an aromatic dicarboxylic acid as a constituent component, the melting point of the resin becomes high, so that the aliphatic dicarboxylic acid component or the aliphatic diol component is added to the aliphatic polyester. In addition to being able to copolymerize in a larger amount than in the case of, the resin melting point is the same as that of the aliphatic polyester, but it is possible to design a resin with increased flexibility, and since an inexpensive aromatic dicarboxylic acid is used, It can be manufactured at a lower cost than polyester.

As the polylactic acid in the present invention, poly L-lactic 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.

A small amount of a chain extender such as a diisocyanate compound, an epoxy compound or an acid anhydride can be used for the purpose of increasing the molecular weight. The compounding ratio of the aliphatic / aromatic copolyester having a glass transition temperature of 0 ° C. or less and the polylactic acid constituting the film or sheet of the present invention is a mass ratio of (aliphatic / aromatic copolyester) / ( Polylactic acid) = 99/1 to 60/40 (mass%)
It is preferably in the range of. When the compounding ratio of the aliphatic / aromatic copolyester exceeds 99% by mass, the obtained film or sheet is rubber-like and has a high elongation and a low waist strength, and the waist strength of the film or sheet is required. It becomes unsuitable for packaging applications and containers. Further, since the adhesiveness is remarkably increased, blocking occurs and the productivity is reduced. On the other hand, when the proportion of the biodegradable aliphatic / aromatic copolyester is less than 60% by mass, the proportion of polylactic acid is increased, so that the physical properties are significantly decreased due to hydrolysis under high temperature and high humidity, which is preferable. Absent. Therefore, the compounding ratio of the aliphatic / aromatic copolyester having a glass transition temperature of 0 ° C. or lower and the polylactic acid is (aliphatic / aromatic copolyester) / (polylactic acid) = 95/5 in mass ratio. ~ 60 /
More preferably in the range of 40 (mass%), 90
The range of / 10 to 70/30 (mass%) is more preferable.

In the present invention, talc, calcium carbonate, and talc are used for the purpose of improving slipperiness and blocking resistance.
You may mix inorganic fillers, such as silica. The average particle diameter of the inorganic filler is preferably in the range of 0.5 to 15 μm. Further, the compounding ratio of the inorganic filler is 1 to 2
It is preferably in the range of 0 mass%. If the blending ratio of the inorganic filler is less than 1% by mass, the effect of the lubricant and the anti-blocking material possessed by the inorganic filler does not appear, and if the blending ratio exceeds 20% by mass, the inorganic filler in the film is disadvantageous. It is not preferable because the mechanical properties of the film are significantly deteriorated. An organic lubricant may be used in combination with the above inorganic filler.

In addition, the resin composition constituting the film or sheet of the present invention contains a plasticizer, an anti-UV agent, an antioxidant, a heat stabilizer, a flame retardant, an antistatic agent, a surface wetting improver, depending on the application. , Pigments, organic additives, organic lubricants and the like may be added.

The molded product made of the film or sheet having the above-mentioned structure has a small deformation even in a high temperature and high humidity atmosphere and has excellent resistance to moisture and heat. Therefore, a stretch film or a wrap film for packaging, or a food container. In addition to being suitable for use as a tray, a blister case (pack), etc., as well as for use as a sealant.

[0017]

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) Tensile strength (MPa): Measured according to the method described in JIS K-7127. (2) Tensile elongation (%): Measured according to the method described in JIS K-7127. (3) Tensile elastic modulus (GPa): Measured according to the method described in JIS K-7127. (4) Impact strength (J): Using a film impact tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.), using a pendulum capacity of 30 kg · cm and an impact head of 12.7 mmΦ in an atmosphere of a measurement temperature of 23 ° C. and 50% RH. It was measured. (5) Blocking: 1 film or sheet on the paper tube
After the film or sheet was wound around 00 m and left at room temperature for 1 day, blocking of the film or sheet was observed when the film or sheet was unwound again. Example 1 80% by mass of aliphatic / aromatic copolyester (Ecoflex F, manufactured by BASF) having a glass transition temperature of -35 ° C, a melting point of 167 ° C, and a D-lactic acid content of 1.2 mol%. 20 wt% of polylactic acid having a weight average molecular weight of 195,000 (Nature Works, manufactured by Cargill Dow) was blended. Then, this raw material is screwed with a circular die having a diameter of 100 mm and a screw diameter of 45 mm.
L / D = 26 using a single-screw extruder, set temperature 200 ℃
Was melt extruded, and 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
A film having a thickness of 40 μm and a film folding width of 540 mm was prepared by winding the film with a winding machine for 100 m.

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

[0020]

[Table 1] Example 2 Talc having an average particle size of 2.75 μm (MW HS-T, manufactured by Hayashi Kasei Co., Ltd.) was blended as a lubricant, and the blending ratio of the aliphatic / aromatic copolyester, polylactic acid and talc was adjusted to
(Aliphatic / aromatic copolyester) / (polylactic acid)
/ (Talc) = 83/15/2 (mass%). Then, this raw material was fed with a screw diameter of 50 mm and L / D (length /
(Caliber) = 21 using a single-screw extruder (manufactured by Japan Steel Works, Ltd.), the extrusion temperature is 210 ° C., and the thickness is 25 by the T-die method.
A sheet having a width of 0 μm and a width of 300 mm was prepared.

Table 1 shows the physical properties and the like of the obtained sheet. The film obtained in Example 1 is composed of biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or lower and polylactic acid, and therefore has excellent mechanical properties and flexibility. Met. Further, since the film was flexible and the elongation was suppressed, it was difficult for the film to have wrinkles, and no blocking of the film was observed.

The sheet obtained in Example 2 was excellent in flexibility and impact strength, and blocking was not observed at all. Comparative Example 1 Aliphatic polyester (Bionore # 3001 manufactured by Showa High Polymer Co., Ltd.) instead of the aliphatic / aromatic copolyester
70% by mass of this aliphatic polyester and 30% by mass of polylactic acid were used as a raw material. Otherwise, the same as Example 2, except that the thickness was 250 μm and the width was 300 mm.
Created a sheet of.

Table 1 shows the physical properties and the like of the obtained sheet. Comparative Example 2 95% by mass of aliphatic / aromatic copolyester (Ecoflex F, manufactured by BASF) and 5% by mass of talc were used without using polylactic acid. A film having a thickness of 40 μm and a width of 540 mm was obtained in the same manner as in Example 1 except for the above.

The physical properties and the like of the obtained film are shown in Table 1.
The sheet obtained in Comparative Example 1 exhibited excellent mechanical properties, but the price of the aliphatic polyester as a raw material was high, and there was a cost problem industrially.

The film obtained in Comparative Example 2 had a large elongation, and when wound on a roll, blocking between the films occurred due to tightness of winding. Furthermore, when unwound from a roll, wrinkles were remarkably generated, and there was a practical problem in applying it to a sealant or the like.

[0026]

According to the present invention, the glass transition temperature is 0 ° C.
The following biodegradable aliphatic-aromatic copolyester,
By using a film or sheet made of a resin composition containing polylactic acid as a main component, the film or sheet has excellent mechanical properties such as impact resistance and also has flexibility. Also,
Since it has excellent moldability, it can be suitably used as a packaging material.

Molded articles made of these biodegradable films or sheets are stretch films or wrap films for packing, sealants, waterproof / water-proof sheets, sound-proof sheets,
It can be suitably used for trays, blister (packs) and the like.

Claims (5)

[Claims] 1. A biodegradable film comprising a resin composition containing a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or lower and polylactic acid as main components. 2. The blending ratio of the aliphatic / aromatic copolyester having a glass transition temperature of 0 ° C. or less and polylactic acid is
(Aliphatic / aromatic copolyester) / (polylactic acid)
= 99/1 to 60/40 (mass%) in range, The biodegradable film according to claim 1, characterized in that. 3. A biodegradable sheet comprising a resin composition containing a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or lower and polylactic acid as main components. 4. The compounding ratio of the aliphatic / aromatic copolyester having a glass transition temperature of 0 ° C. or less and polylactic acid is
(Aliphatic / aromatic copolyester) / (polylactic acid)
= 99/1 to 60/40 (mass%) is in the range, and the biodegradable sheet according to claim 3. 5. A molded article comprising the biodegradable film or sheet according to any one of claims 1 to 4.